Method for manufacturing electrostatic charge image development toner

Abstract

To provide a method for manufacturing an electrostatic charge image development toner, capable of achieving both low temperature fixability and high temperature offset resistance and suppressing fog at low temperature and low humidity.SOLUTION: A method for manufacturing for electrostatic charge image development toner comprises the step of melting and mixing a binder resin containing raw material using a continuous system two open roll type kneader. The binder resin includes an amorphous polyester resin of 20 mass% or more and 80 mass% or less having a storage elastic modulus at 100°C of 30,000 Pa or less; and when setting the front roll peripheral speed of the kneader to Vf and the back roll peripheral speed thereof to Vb, the fill factor of the raw material inputted into the kneader changes in a range of 1.0 or more and 5.0 or less so that a difference rate ΔV between the peripheral speeds of the two rolls calculated from 100×(Vf-Vb) / Vf satisfies the formula (A) :0≤ΔV0≤10 and the formula (B):ΔV1-ΔV0>0, (where, ΔV0 is ΔV when starting to input the raw material, and ΔV1 shows ΔV after change.).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a toner for developing electrostatic images used in developing latent images formed in electrophotography, electrostatic recording, electrostatic printing and the like. [Background technology]

[0002] In the toner manufacturing process, a method of using an open-roll type kneader for melting and kneading raw materials is being considered. As shown in Patent Document 1, the open-roll type kneader has the advantage of being able to lower the temperature during kneading. Therefore, it is possible to reduce the difference in viscosity between the amorphous resin used as the main component of the binder resin and low-melting point substances such as crystalline polyester resin and wax, and also to improve the dispersibility of the low-melting point substance by creating a difference in the peripheral speed of the rolls.

[0003] On the other hand, in recent years, low-temperature fixability has become an essential performance due to the demand for power saving, and in addition, high-temperature offset resistance is also required to widen the temperature range in which fixation is possible, so it is necessary to achieve both low-temperature fixability and high-temperature offset resistance. For this purpose, the molecular weight design of the binder resin requires many low-molecular components and a small amount of high-molecular components. Furthermore, even when using raw materials with large viscosity differences that contain a lot of low-melting point substances such as crystalline polyester resins and waxes, they must be kneaded uniformly.

[0004] However, when the viscosity difference between the raw materials is large, poor adhesion to the kneader and poor dispersion occur. Therefore, in order to solve the poor kneading problem in the open roll type kneader, measures such as those described in Patent Documents 2 and 3 have been taken. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2000-75543 A [Patent Document 2] JP 2011-69887 A [Patent Document 3] JP 2007-168317 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the open-roll type kneader, the kneaded material does not stick to the rolls sufficiently immediately after the start of kneading because the heat quantity of the kneaded material is small, and if kneading is continued in this state, the dispersibility of low-viscosity components such as crystalline polyester resin and wax decreases. As a result, it becomes difficult to achieve both low-temperature fixability and high-temperature offset resistance, and fogging occurs in a low-temperature and low-humidity environment. In Patent Document 1, an open roll type kneader equipped with multiple supply ports must be used, and in Patent Document 2, the composition of the crystalline polyester resin is limited, making it difficult to further improve the toner performance. In Patent Document 3, a belt can be added to improve the loss of raw materials, but it cannot improve the sticking problem.

[0007] The present invention relates to a method for producing a toner for developing electrostatic images, which is capable of achieving both low-temperature fixing properties and high-temperature offset resistance and is suppressed from causing fogging under low-temperature and low-humidity conditions. [Means for solving the problem]

[0008] The present invention relates to a method for producing a toner for developing electrostatic images, the method comprising the step of melting and kneading a raw material containing a binder resin by using a continuous two-open roll type kneader, the binder resin containing 20% ​​by mass or more and 80% by mass or less of an amorphous polyester resin having a storage modulus of 30,000 Pa or less at 100° C., the peripheral speed of a front roll of the kneader being Vf and the peripheral speed of a back roll being Vb, the difference rate ΔV between the peripheral speeds of the two rolls calculated from 100×(Vf−Vb) / Vf being Formula (A): 0≦ΔV0≦10, and Formula (B): ΔV1-ΔV0>0 (In the formula, ΔV0 is the ΔV at the start of raw material input, and ΔV1 is the ΔV after the change.) The present invention relates to a method for producing a toner for developing electrostatic images, wherein the filling rate of the raw materials fed into the kneader is changed within a range of 1.0 to 5.0 so as to satisfy the above. Effect of the Invention

[0009] According to the method of the present invention, a toner for developing electrostatic images can be obtained which achieves both low-temperature fixing ability and high-temperature offset resistance and also suppresses fogging under low-temperature and low-humidity conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for producing a toner for developing electrostatic images of the present invention is characterized in that an amorphous polyester resin having a predetermined storage modulus is used as a part of the binder resin, and when the raw materials are melt-kneaded using a continuous two-open roll type kneader, the difference in peripheral speed between the front roll and the back roll is made small to start kneading, and the difference in peripheral speed is changed during kneading.

[0011] By using an amorphous polyester resin with a low storage modulus, low-temperature fixing property is improved, but in recent years, there has been a strong demand for energy saving, and in order to achieve even lower temperature fixing, it is necessary to use a low-melting wax or a large amount of crystalline polyester. In that case, raw materials with a large viscosity difference are kneaded, and in an open-roll type kneader, the sticking of the raw materials to the front roll becomes an issue. A continuous two-roll open-roll type kneader has two rolls, a front roll and a back roll, and usually the front roll rotates faster than the back roll to knead the raw material while it is stuck to the front roll. However, as a result of the inventors' intensive study of the operating conditions of the open-roll type kneader, they found that even if the raw material has a viscosity difference, it is possible to improve the sticking of the raw material to the front roll by starting kneading with a small difference in the peripheral speed (rotation speed) between the front roll and the back roll, supplying the raw material to the kneader in an amount that covers the surface of the front roll, and then changing the setting so that the peripheral speed of the front roll is faster than the peripheral speed of the back roll when the filling rate of the raw material is within a certain range. This improves the dispersibility of each raw material, making the composition within one toner particle uniform, making it possible to achieve both low-temperature fixability and high-temperature offset resistance, and also suppressing fogging in a low-temperature, low-humidity environment because the charge distribution of the toner particles is uniform.

[0012] The binder resin in the present invention contains a predetermined amount of an amorphous polyester resin (amorphous polyester resin L) having a storage modulus of 30,000 Pa or less at 100° C. The storage modulus of the amorphous polyester resin L at 100° C. is 30,000 Pa or less, preferably 27,000 Pa or less, more preferably 24,000 Pa or less, and even more preferably 20,000 Pa or less, from the viewpoint of low-temperature fixability, and is preferably 500 Pa or more, more preferably 650 Pa or more, and even more preferably 800 Pa or more, from the viewpoint of high-temperature offset resistance. The storage modulus of the resin can be adjusted by the monomer composition, reaction temperature, reaction time, etc.

[0013] The crystallinity of a resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the value of [softening point / maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. On the other hand, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index is greater than 1.4, preferably greater than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum endothermic peak temperature is the melting point.

[0014] As the amorphous polyester resin (amorphous polyester resin L), an amorphous polyester resin or an amorphous composite resin in which a polyester resin is bonded to a styrene resin is preferred.

[0015] The amorphous polyester resin is preferably a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing an aromatic dicarboxylic acid compound.

[0016] Examples of the alkylene oxide adduct of bisphenol A include those represented by the formula (I):

[0017] [ka]

[0018] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) Preferred is a compound represented by the following formula:

[0019] From the viewpoint of low-temperature fixing ability, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0020] Examples of other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane and other trihydric or higher alcohols.

[0021] Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0022] From the viewpoint of controlling the storage modulus, the content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0023] Examples of other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with a hydrocarbon group, aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0024] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0025] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0026] From the viewpoint of adjusting the softening point of the polyester resin, the equivalent ratio of the carboxy group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

[0027] The amorphous polyester resin can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and further, if necessary, in the presence of an esterification promoter, a polymerization inhibitor, etc., at a temperature of preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0028] In the present invention, the polyester resin may be modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc., and among the modified polyester resins, urethane-modified polyester resins in which polyester resins are urethane-extended with a polyisocyanate compound are preferred.

[0029] The polyester resin in the composite resin is similar to the amorphous polyester resin described above, and the styrene-based resin is an addition polymer of raw material monomers containing at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

[0030] The content of the styrene compound, preferably styrene, in the raw material monomer of the styrene-based resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more from the viewpoint of storage stability, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less from the viewpoint of low-temperature fixability.

[0031] The styrene-based resin may also contain, as a raw material monomer, an alkyl (meth)acrylate ester having an alkyl group with 7 or more carbon atoms. Examples of the alkyl (meth)acrylate ester include 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, and (iso)stearyl (meth)acrylate. It is preferable to use one or more of these. In this specification, "(iso)" means that both the case where this group is present and the case where it is not present are included, and when these groups are not present, it indicates that it is normal. Furthermore, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

[0032] From the viewpoint of improving the low-temperature fixing property of the toner, the number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester as a raw material monomer of the styrene-based resin is preferably 7 or more, more preferably 8 or more, and preferably 12 or less, more preferably 10 or less. The number of carbon atoms in the alkyl ester refers to the number of carbon atoms derived from the alcohol component constituting the ester.

[0033] The raw material monomers for the styrene-based resin may include raw material monomers other than styrene compounds and (meth)acrylic acid alkyl esters, for example, ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylates such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0034] The addition polymerization reaction of raw material monomers for the styrene-based resin can be carried out by a conventional method in the presence of a polymerization initiator such as dibutyl peroxide or dicumyl peroxide, a polymerization inhibitor, a crosslinking agent, or the like, in the presence of an organic solvent or without a solvent. The temperature conditions are preferably 110° C. or higher, more preferably 140° C. or higher, and preferably 200° C. or lower, more preferably 170° C. or lower.

[0035] When an organic solvent is used in the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone, etc. can be used. The amount of the organic solvent used is preferably 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the raw material monomer of the styrene-based resin.

[0036] The composite resin is preferably a resin in which a polyester resin and a styrene-based resin are bonded together, and more preferably a resin in which the polyester resin and the styrene-based resin are chemically bonded together via a bireactive monomer that can react with both the raw material monomers of the polyester resin and the raw material monomers of the styrene-based resin.

[0037] The bireactive monomer is preferably a compound having at least one functional group selected from the group consisting of hydroxyl group, carboxyl group, epoxy group, primary amino group and secondary amino group, preferably hydroxyl group and / or carboxyl group, more preferably carboxyl group and ethylenically unsaturated bond in the molecule, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid and maleic anhydride, and from the viewpoint of reactivity of polycondensation reaction and addition polymerization reaction, still more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid and fumaric acid. However, when used together with a polymerization inhibitor, a polyvalent carboxylic acid compound having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer of polyester resin. In this case, fumaric acid etc. is not a bireactive monomer but a raw material monomer of polyester resin.

[0038] The amount of the bireactive monomer used is preferably 1 mol or more, more preferably 2 mol or more, relative to 100 mol of the total of the alcohol components of the polyester resin, from the viewpoint of increasing the dispersibility of the styrene resin and the polyester resin and improving the dispersibility of the raw materials in the toner, and is preferably 30 mol or less, more preferably 20 mol or less, and even more preferably 10 mol or less, from the viewpoint of improving the low-temperature fixing property of the toner. The amount of the bireactive monomer used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the raw material monomers of the styrene resin, from the viewpoint of increasing the dispersibility of the styrene resin and the polyester resin and improving the dispersibility of the raw materials in the toner, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of improving the low-temperature fixability of the toner. Here, the polymerization initiator is included in the total amount of the raw material monomers of the styrene resin.

[0039] Specifically, the composite resin is preferably produced by the following method: When a bireactive monomer is used, the bireactive monomer is preferably used in an addition polymerization reaction together with a raw material monomer of a styrene-based resin from the viewpoint of improving the dispersibility of the raw material in the toner and the low-temperature fixing property of the toner.

[0040] (i) A method in which a step (A) of polycondensation reaction of raw material monomers for a polyester resin is followed by a step (B) of addition polymerization reaction of raw material monomers for a styrene-based resin and a bireactive monomer. In this method, step (A) is carried out under reaction temperature conditions suitable for polycondensation reaction, and the reaction temperature is lowered to carry out step (B) under temperature conditions suitable for addition polymerization reaction. The raw material monomers of the styrene-based resin and the bireactive monomer are preferably added to the reaction system at a temperature suitable for the addition polymerization reaction. The bireactive monomer not only undergoes the addition polymerization reaction but also reacts with the polyester resin. After step (B), the reaction temperature is increased again, and if necessary, a raw material monomer of a polyester resin having a valence of 3 or more and serving as a crosslinking agent is added to the polymerization system, so that the polycondensation reaction of step (A) and the reaction with the bireactive monomer can be further promoted.

[0041] (ii) A method in which step (B) of an addition polymerization reaction of raw material monomers for a styrene-based resin and a bireactive monomer is followed by step (A) of a polycondensation reaction of raw material monomers for a polyester resin. In this method, step (B) is carried out under reaction temperature conditions suitable for an addition polymerization reaction, and then the reaction temperature is raised and the polycondensation reaction of step (A) is carried out under temperature conditions suitable for a polycondensation reaction. The bireactive monomer is involved in both the addition polymerization reaction and the polycondensation reaction. The raw material monomers of the polyester resin may be present in the reaction system during the addition polymerization reaction, or may be added to the reaction system under temperature conditions suitable for the polycondensation reaction. In the former case, the progress of the polycondensation reaction can be controlled by adding an esterification catalyst at a temperature suitable for the polycondensation reaction.

[0042] (iii) A method in which the reaction is carried out under conditions in which step (A) of polycondensation reaction of raw material monomers of a polyester resin and step (B) of addition polymerization reaction of raw material monomers of a styrene-based resin and a bireactive monomer proceed in parallel. In this method, it is preferable to carry out step (A) and step (B) in parallel under reaction temperature conditions suitable for addition polymerization reaction, raise the reaction temperature, add a raw material monomer of a polyester resin having a valence of 3 or more as a crosslinking agent to the polymerization system as necessary under temperature conditions suitable for polycondensation reaction, and further carry out the polycondensation reaction of step (A). In this case, under temperature conditions suitable for polycondensation reaction, a polymerization inhibitor can be added to proceed with only the polycondensation reaction. The bireactive monomer is involved in both the addition polymerization reaction and the polycondensation reaction.

[0043] In the above method (i), a prepolymerized polycondensation resin may be used instead of the step (A) in which a polycondensation reaction is carried out. In the above method (iii), when the reaction is carried out under conditions in which the steps (A) and (B) proceed in parallel, a mixture containing raw material monomers for a styrene resin may be dropped into a mixture containing raw material monomers for a polyester resin to carry out the reaction.

[0044] The above methods (i) to (iii) are preferably carried out in the same container.

[0045] The mass ratio of the polyester resin to the styrene-based resin in the composite resin (polyester resin / styrene-based resin) is preferably 98 / 2 or less, more preferably 95 / 5 or less, and even more preferably 90 / 10 or less from the viewpoint of improving the dispersibility of the raw materials in the toner, and is preferably 60 / 40 or more, more preferably 70 / 30 or more, and even more preferably 75 / 25 or more from the viewpoint of low-temperature fixability. In the above calculation, the mass of the polyester resin is the amount of raw material monomers of the polyester resin used, and the amount of the bireactive monomer is included in the amount of raw material monomers of the polyester resin.

[0046] The softening point of the amorphous polyester resin L is preferably 80°C or higher, more preferably 85°C or higher, and even more preferably 90°C or higher from the viewpoint of high-temperature offset resistance, and is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 115°C or lower from the viewpoint of low-temperature fixability.

[0047] The glass transition temperature of the amorphous polyester resin L is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 53°C or higher, from the viewpoint of heat-resistant storage stability, and is preferably 80°C or lower, and more preferably 70°C or lower, from the viewpoint of low-temperature fixability.

[0048] From the viewpoint of charging stability, the acid value of the amorphous polyester resin L is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, and is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less.

[0049] The content of the amorphous polyester resin L in the binder resin is 20% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more, and from the viewpoint of suppressing fogging under low temperature and low humidity conditions, it is 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less.

[0050] From the viewpoint of high-temperature offset resistance, the binder resin preferably contains an amorphous polyester resin (amorphous polyester resin H) having a storage modulus at 100° C. of more than 30,000 Pa. The storage modulus at 100° C. of the amorphous polyester resin H is preferably 35,000 Pa or more, more preferably 40,000 Pa or more, even more preferably 45,000 Pa or more, and is preferably 500,000 Pa or less, more preferably 200,000 Pa or less, even more preferably 100,000 Pa or less.

[0051] The raw material monomers and manufacturing method of amorphous polyester resin H are the same as those of amorphous polyester resin L, but from the viewpoint of fixing property, it is preferable that the carboxylic acid component contains a succinic acid derivative substituted with a hydrocarbon group and a carboxylic acid compound having a valence of three or more.

[0052] The hydrocarbon group in the succinic acid derivative substituted with a hydrocarbon group is preferably an alkyl group or an alkenyl group.Therefore, specific examples of the succinic acid derivative substituted with a hydrocarbon group include dodecyl succinic acid, dodecenyl succinic acid, tetrapropenyl succinic acid, decenyl succinic acid, their acid anhydrides, and their alkyl esters having 1 to 3 carbon atoms.Among these, from the viewpoint of low-temperature fixing property, dodecenyl succinic acid, tetrapropenyl succinic acid, or their acid anhydrides are preferred, and dodecenyl succinic acid is more preferred.

[0053] From the viewpoint of hydrophobicity, the number of carbon atoms in the hydrocarbon group in the succinic acid derivative is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, and is preferably 20 or less, more preferably 18 or less, even more preferably 16 or less.

[0054] From the viewpoint of hydrophobicity, the succinic acid derivative preferably contains at least one or more types selected from the group consisting of succinic acid substituted with an alkyl group having from 10 to 18 carbon atoms and succinic acid substituted with an alkenyl group having from 10 to 18 carbon atoms, and more preferably contains at least one or more types selected from the group consisting of succinic acid substituted with an alkyl group having from 12 to 16 carbon atoms and succinic acid substituted with an alkenyl group having from 12 to 16 carbon atoms.

[0055] The content of the succinic acid derivative in the carboxylic acid component is preferably 1 mol % or more, more preferably 5 mol % or more, and from the viewpoint of storage stability, is preferably 40 mol % or less, more preferably 35 mol % or less, even more preferably 20 mol % or less, and even more preferably 15 mol % or less.

[0056] The content of the trivalent or higher carboxylic acid compound in the carboxylic acid component is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 3 mol % or more, and from the viewpoint of low-temperature fixability, is preferably 45 mol % or less, more preferably 35 mol % or less, and even more preferably 30 mol % or less.

[0057] The softening point of the amorphous polyester resin H is preferably 110°C or higher, more preferably 115°C or higher, and even more preferably 120°C or higher, from the viewpoint of high-temperature offset resistance, and is preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower, from the viewpoint of low-temperature fixability.

[0058] The glass transition temperature of the amorphous polyester resin H is preferably 45° C. or higher, more preferably 50° C. or higher, and even more preferably 53° C. or higher, from the viewpoint of heat-resistant storage stability, and is preferably 80° C. or lower, and more preferably 70° C. or lower, from the viewpoint of low-temperature fixability.

[0059] From the viewpoint of charging stability, the acid value of the amorphous polyester resin H is preferably 1 mgKOH / g or more, more preferably 5 mgKOH / g or more, and preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less.

[0060] The content of the amorphous polyester resin H in the binder resin is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less.

[0061] The mass ratio of amorphous polyester resin L to amorphous polyester resin H (amorphous polyester resin L / amorphous polyester resin H) is preferably 20 / 80 or more, more preferably 25 / 75 or more, even more preferably 30 / 70 or more, and is preferably 80 / 20 or less, more preferably 75 / 25 or less, even more preferably 70 / 30 or less.

[0062] The total content of the amorphous polyester resin L and the amorphous polyester resin H in the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. When a crystalline polyester resin described below is contained, the total content is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0063] From the viewpoint of low-temperature fixability, it is preferable that the binder resin further contains a crystalline polyester resin (crystalline polyester resin C).

[0064] The crystalline polyester resin C is preferably a crystalline polyester resin or a crystalline composite resin in which a polyester resin is bonded to a styrene resin.

[0065] The crystalline polyester resin is preferably a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

[0066] Examples of the aliphatic diol include ethylene glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0067] From the viewpoint of achieving appropriate compatibility with the amorphous polyester, the aliphatic diol preferably has 2 or more carbon atoms and preferably has 14 or less, more preferably 12 or less carbon atoms.

[0068] From the viewpoint of improving the low-temperature fixing property of the toner, the aliphatic diol preferably has a hydroxyl group at the end of the carbon chain, and is more preferably an α,ω-straight-chain alkanediol.

[0069] The alcohol component may contain alcohol other than the aliphatic diol, but the content of the aliphatic diol in the alcohol component is preferably 70 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0070] Examples of other alcohol components include aromatic diols such as alkylene oxide adducts of bisphenol A, and trihydric or higher alcohols such as glycerin.

[0071] Examples of the aliphatic dicarboxylic acid compound include succinic acid (carbon number: 4), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanoic diacid (carbon number: 12), tetradecanoic diacid (carbon number: 14), succinic acid having an alkyl group or an alkenyl group, anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms. In the present invention, the carboxylic acid compound includes not only free acids, but also anhydrides that decompose during the reaction to generate acids, and alkyl esters having 1 to 3 carbon atoms. However, the number of carbon atoms of the alkyl group of the alkyl ester moiety is not included in the number of carbon atoms of the aliphatic dicarboxylic acid compound.

[0072] The chain hydrocarbon group in the aliphatic dicarboxylic acid compound may be linear or branched, and the number of carbon atoms in the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 6 or more, and even more preferably 10 or more, from the viewpoint of appropriate compatibility with the amorphous polyester resin, and is preferably 14 or less, more preferably 13 or less.

[0073] The carboxylic acid component may contain a carboxylic acid compound other than an aliphatic dicarboxylic acid compound, but the content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 100 mol %.

[0074] Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl ester compounds of these acids having 1 to 3 carbon atoms.

[0075] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

[0076] The crystalline polyester resin can be produced by polycondensing an alcohol and a carboxylic acid compound in the same manner as the amorphous polyester resin. The reaction temperature of the polycondensation is preferably 120° C. or higher, more preferably 180° C. or higher, and preferably 230° C. or lower, more preferably 220° C. or lower.

[0077] The polyester resin in the crystalline composite resin is similar to the above-mentioned crystalline polyester resin.

[0078] The content of the styrene compound, preferably styrene, in the raw material monomer of the styrene-based resin is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably 100 mass% from the viewpoint of storage stability.

[0079] Other than that, the crystalline composite resin is similar to the amorphous composite resin.

[0080] The softening point of the crystalline polyester resin C is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, and is preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 100°C or lower.

[0081] The melting point of the crystalline polyester resin C is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, and is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower.

[0082] The storage modulus of the crystalline polyester resin C at 100°C is preferably 300 Pa or more, more preferably 350 Pa or more, even more preferably 400 Pa or more, and is preferably 3,000 Pa or less, more preferably 2,500 Pa or less, even more preferably 2,000 Pa or less.

[0083] The content of the crystalline polyester resin C in the binder resin is preferably 1 mass % or more, more preferably 2 mass % or more, even more preferably 3 mass % or more, and preferably 40 mass % or less, more preferably 30 mass % or less, even more preferably 20 mass % or less.

[0084] Examples of binder resins other than the amorphous polyester resin and the crystalline polyester resin include vinyl resins such as styrene acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins.

[0085] The total content of the amorphous polyester resin L, the amorphous polyester resin H, and the crystalline polyester resin C in the binder resin is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably 100 mass%.

[0086] The content of the binder resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably less than 100% by mass, more preferably 98% by mass or less, even more preferably 95% by mass or less.

[0087] In addition to the binder resin, the toner may contain additives such as a colorant, a release agent, a charge control agent, a magnetic powder, a flowability improver, a conductivity regulator, a reinforcing filler such as a fibrous substance, an antioxidant, a cleaning property improver, etc. In particular, when a release agent is used, the effect of the present invention is more remarkable.

[0088] Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene-polyethylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; ester waxes such as carnauba wax, montan wax, and deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. These may be used alone or in combination of two or more.

[0089] The melting point of the release agent is preferably 60° C. or higher, more preferably 70° C. or higher, from the viewpoint of storage stability, and is preferably 160° C. or lower, more preferably 140° C. or lower, even more preferably 120° C. or lower, and even more preferably 110° C. or lower, from the viewpoint of low-temperature fixability.

[0090] The content of the release agent is, from the viewpoint of the low-temperature fixing property and high-temperature offset resistance of the toner and the viewpoint of dispersibility in the binder resin, preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the binder resin, and is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less.

[0091] As the colorant, dyes, pigments, magnetic materials, etc. used as colorants for toners can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. can be mentioned. In the present invention, the toner may be either a black toner or a color toner.

[0092] From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0093] The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

[0094] Examples of the positively charged charge control agent include nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", "Bontron N-07", "Bontron N-09", and "Bontron N-11" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX Examples of such resins include "VP435" (manufactured by Clariant), etc.; polyamine resins, such as "AFP-B" (manufactured by Orient Chemical Industry Co., Ltd.); imidazole derivatives, such as "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Kasei Corporation); and styrene-acrylic resins, such as "FCA-701PT" and "FCA-201-PS" (manufactured by Fujikura Kasei Co., Ltd.).

[0095] Examples of the negatively chargeable charge control agent include metal-containing azo dyes such as "Varifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", and "Bontron S-36" (all manufactured by Orient Chemical Industry Co., Ltd.), "Aizenspiron Black TRH", and "T-77" (manufactured by Hodogaya Chemical Industry Co., Ltd.); metal compounds of benzilic acid compounds such as "LR-147" and "LR-297" (all manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", and "Bontron E-304" (all manufactured by Orient Chemical Industry Co., Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Industry Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts such as "COPY CHARGE NX VP434 (Clariant), nitroimidazole derivatives, and organometallic compounds.

[0096] From the viewpoint of the charging stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0097] In the present invention, a toner is produced by a method including a step of melt-kneading raw materials including amorphous polyester resin L and, if necessary, amorphous polyester resin H, crystalline polyester resin C, and additives such as a colorant, a release agent, and a charge control agent, using a continuous two-open roll type kneader.

[0098] The mixture to be melt-kneaded may be kneaded all at once or in portions, but it is preferable to mix the mixture in advance in a mixer such as a Henschel mixer or a ball mill and then supply the mixture to an open roll type kneader.

[0099] The open-roll type kneader refers to a kneader in which the melt-kneading section is open and not sealed, and the heat of kneading generated during melt-kneading can be easily dissipated. The continuous two-roll open-roll type kneader used in the present invention is equipped with two rolls (front roll and back roll) arranged in parallel, and is equipped with a raw material supply port and a kneaded material discharge port provided along the axial direction of the rolls.

[0100] In the present invention, when the peripheral speed of the front roll of the open-roll type kneader is Vf and the peripheral speed of the back roll is Vb, the filling rate of the raw material fed into the kneader is changed within a predetermined range so that the difference rate ΔV between the peripheral speeds of the two rolls, calculated from 100×(Vf-Vb) / Vf, satisfies the following formulas (A) and (B). Formula (A): 0≦ΔV0≦10 Formula (B): ΔV1-ΔV0>0 (In the formula, ΔV0 is the ΔV at the start of raw material input, and ΔV1 is the ΔV after the change.)

[0101] In formula (A), ΔV0 is preferably 8 or less, more preferably 5 or less, and further preferably 0.

[0102] In formula (B), the difference between ΔV1 and ΔV0 (ΔV1-ΔV0) is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, and is preferably 75 or less, more preferably 70 or less, even more preferably 68 or less.

[0103] ΔV1 is preferably 20 or more, more preferably 25 or more, even more preferably 30 or more, and is preferably 75 or less, more preferably 70 or less, even more preferably 68 or less.

[0104] The filling rate of the raw material changed from ΔV0 to ΔV1 is 1.0 or more, preferably 1.1 or more, more preferably 1.2 or more, from the viewpoint of improving adhesion of the raw material to the front roll, and is 5.0 or less, preferably 4.0 or less, more preferably 3.0 or less, from the viewpoint of suppressing fogging under low temperature and low humidity conditions.

[0105] In the present invention, the packing ratio of the raw material is calculated from the formula (1) using a volume coefficient calculated from the product of the following scale coefficient and gap coefficient.

[0106] Scale factor = 5.0 x 10 -5 × roll surface area (cm 2 )+0.1558 Gap factor = 0.5 x roll gap (mm) + 0.95 Volume factor = Scale factor x Gap factor

[0107]

number

[0108] The peripheral speed (Vf0) of the front roll before the change in ΔV is preferably 15 m / min or more, more preferably 20 m / min or more, even more preferably 25 m / min or more, and preferably 80 m / min or less, more preferably 78 m / min or less, even more preferably 75 m / min or less.

[0109] The peripheral speed (Vb0) of the back roll before the change in ΔV is preferably 15 m / min or more, more preferably 20 m / min or more, even more preferably 25 m / min or more, and preferably 80 m / min or less, more preferably 78 m / min or less, even more preferably 75 m / min or less.

[0110] To change ΔV, the peripheral speed of the front roll may be increased or the peripheral speeds of both the front roll and the back roll may be changed. From the viewpoint of production stability, however, it is preferable to make ΔV1 larger than ΔV0 by decreasing the peripheral speed of the back roll.

[0111] The difference (Vf0-Vf1) between Vf0 of the front roll and the peripheral speed (Vf1) after the change in ΔV is preferably 10.0 m / min or less, more preferably 5.0 m / min or less, and further preferably 0 m / min, that is, Vf1=Vf0.

[0112] The difference (Vb0-Vb1) between Vb0 of the back roll and the peripheral speed (Vb1) after the change in ΔV is preferably 5.0 m / min or more, more preferably 6.5 m / min or more, even more preferably 8.0 m / min or more, and is preferably 30.0 m / min or less, more preferably 20.0 m / min or less, even more preferably 15.0 m / min or less.

[0113] The temperature of the rolls can be adjusted, for example, by the temperature of a heat medium passed through the inside of the rolls, and the inside of each roll may be divided into two or more parts through which heat mediums of different temperatures are passed. In the present invention, from the viewpoint of making it easier for the raw material to stick to the front roll, it is preferable that the temperature of the front roll is higher than that of the back roll.

[0114] The temperature of the raw material input side of the front roll is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of melting the raw material, and is preferably 160°C or lower, more preferably 155°C or lower, and even more preferably 150°C or lower, from the viewpoint of sticking to the front roll.

[0115] From the viewpoint of production stability, the temperature of the kneaded material discharge side of the front roll is preferably 70°C or higher, more preferably 75°C or higher, and even more preferably 80°C or higher, and from the viewpoint of improving the dispersibility of the raw materials in the toner, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower.

[0116] The temperature of the raw material input side of the back roll is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 30°C or higher, from the viewpoint of melting the raw material, and is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower, from the viewpoint of sticking to the front roll.

[0117] From the viewpoint of production stability, the temperature of the kneaded material discharge side of the back roll is preferably 20° C. or higher, more preferably 25° C. or higher, and even more preferably 30° C. or higher, and from the viewpoint of improving the dispersibility of the raw materials in the toner, it is preferably 110° C. or lower, more preferably 100° C. or lower, and even more preferably 80° C. or lower.

[0118] It is preferable that the temperature of the raw material input side of the front roll is higher than that of the kneaded material discharge side, and the temperature difference between the raw material input side and the kneaded material discharge side of the front roll is preferably 5°C or more, more preferably 10°C or more, even more preferably 20°C or more, from the viewpoint of preventing the kneaded material from detaching from the roll and from the viewpoint of reducing the mechanical force during melt kneading and suppressing heat generation, and is preferably 60°C or less, more preferably 55°C or less.

[0119] It is preferable that the temperature difference between the kneaded material discharge side and the raw material input side of the back roll is small, and the temperature difference between the raw material input side and the kneaded material discharge side of the back roll is preferably 50°C or less, more preferably 30°C or less, and even more preferably 0°C, from the viewpoint of reducing the mechanical force during melt kneading and suppressing heat generation.

[0120] The temperature of the raw material input side of the front roll and the back roll refers to the set temperature of the raw material input end, and the temperature of the kneaded material discharge side refers to the set temperature of the kneaded material discharge end.

[0121] There are no particular limitations on the structure, size, material, etc. of each roll. The roll surface has grooves used for kneading, and the shape of these grooves may be linear, spiral, wavy, uneven, or the like.

[0122] After the melt-kneading, the kneaded mixture is cooled appropriately until it reaches a pulverizable hardness, and then, if necessary, a pulverization step and a classification step are carried out to obtain toner particles. Here, "cooling" refers to cooling the kneaded mixture to 0°C or higher and 50°C or lower, or to cooling to the glass transition temperature of the binder resin in the kneaded mixture or lower.

[0123] In pulverizing the kneaded product, the kneaded product may be pulverized to the desired particle size all at once or in stages. From the viewpoint of efficient and more uniform pulverization, however, it is preferable to perform the pulverization in two stages: coarse pulverization and fine pulverization.

[0124] Examples of the crushing machine used for the coarse crushing include a hammer mill, a cutter mill, an atomizer, and a rotoplex.

[0125] In the coarse pulverization, it is preferable to pulverize until the maximum diameter is 3 mm or less. For example, a pulverized material having a maximum diameter of 3 mm or less can be obtained by appropriately coarsely pulverizing the kneaded material until the particle size is about 0.05 mm or more and 3 mm or less, and then passing the kneaded material through a sieve with 3 mm openings.

[0126] Examples of the pulverizer used for fine pulverization include jet mills such as a fluidized bed jet mill and an impact plate jet mill, and mechanical mills.

[0127] The degree of pulverization is preferably adjusted appropriately depending on the desired particle size of the toner particles.

[0128] Examples of classifiers used for classification include airflow classifiers, inertial classifiers, sieve classifiers, etc. In the classification step, the pulverized material removed due to insufficient pulverization may be subjected to the pulverization step again, and the pulverization step and the classification step may be repeated as necessary.

[0129] In the present invention, it is preferable to further include an external addition step of mixing the obtained toner particles with an external additive.

[0130] Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles, and two or more of them may be used in combination. Among these, silica is preferred, and from the viewpoint of the fluidity and chargeability of the toner, hydrophobic silica that has been subjected to a hydrophobic treatment is more preferred.

[0131] Examples of hydrophobic treatment agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0132] From the viewpoint of the chargeability and fluidity of the toner, the average particle size of the external additive is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, and is preferably 250 nm or less, more preferably 200 nm or less, even more preferably 90 nm or less.

[0133] From the viewpoint of the electrostatic chargeability and fluidity of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the toner particles before being treated with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

[0134] The volume median particle size (D 50 ) is preferably 3 μm or more, more preferably 4 μm or more, and is preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle size. In addition, when the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is regarded as the volume median particle size of the toner.

[0135] The toner obtained by the method of the present invention can be used as it is as a toner for one-component development, or as a toner for two-component development mixed with a carrier, in an image forming apparatus of a one-component development system or a two-component development system, respectively. EXAMPLES

[0136] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Physical properties of resins and the like can be measured by the following methods.

[0137] [Storage modulus of resin] The measurement is carried out using a viscoelasticity measuring device (rheometer) RDA-III type (manufactured by Rheometrics Co., Ltd.). Measurement jig: 25mm diameter parallel plate Measurement sample: 1 g of resin / measurement sample is pelletized by applying pressure at 2 ton for 20 minutes. Measurement conditions: Start measurement at 120° C., then cool to 40° C. Then reheat from 40° C. to 160° C. The storage modulus (Pa) at 100° C. during this reheating is measured. The conditions of the measuring device are set as follows. Geometry:Parallel Plate(25mm) Radius: 12.5(mm) Gap: Gap at 120℃ After raising the temperature inside the measuring device to 120°C, place 1g of pelletized sample on the parallel plates. After the molten toner is brought into close contact with the upper and lower plates, the Gap where the Axial Force is set to 0 is entered. 1.Dynamic Mechanical Analysis Frequency / Temperature Sweep 2. Test Parameters Strain: 0.05(%) Initial Temperature: 40(℃) 3.Sweep Parameters Sweep Type: Discrete Final temperature: 160(℃) Step Size: 1 (℃) Soak Time: 30(s) Frequency: 6.28 (rad / s) 4.Options Delay Before Test: 30(s) Correlation Delay: 0.0 (Cycles) 1Cycle Correlation:No Auto tension: Yes

[0138] [Softening point of resin] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1g of sample is heated at a temperature increase rate of 6℃ / min while applying a load of 1.96MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1mm and a length of 1mm. The amount of plunger descent of the flow tester is plotted against the temperature, and the temperature at which half of the sample has flowed out is taken as the softening point.

[0139] [Maximum endothermic peak temperature of resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), weigh 0.01 to 0.02 g of sample into an aluminum pan, cool from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintain at 0°C for 1 minute. Then, measure at a rate of 10°C / min. The temperature of the peak with the largest peak area among the observed endothermic peaks is regarded as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is regarded as the melting point.

[0140] [Glass transition temperature of resin] Using a differential scanning calorimeter "DSC Q20" (manufactured by TA Instruments Japan), 0.01 to 0.02 g of sample is weighed into an aluminum pan, heated to 200°C, and cooled from that temperature to -10°C at a rate of 10°C / min. The sample is then heated at a rate of 10°C / min and measured. The glass transition temperature is the temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

[0141] [Acid value of resin] Measurements are performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and a mixture of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0142] [Melting point of release agent] Using a differential scanning calorimeter "DSC Q20" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated to 180°C at a rate of 10°C / min and measured. The maximum endothermic peak temperature observed from the melting endothermic curve obtained therefrom is taken as the melting point of the release agent.

[0143] [Average particle size of external additives] The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average of major and minor diameters) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these by number.

[0144] [Volume median particle size of toner (D 50 )〕 Measuring instrument: Coulter Multisizer III (manufactured by Beckman Coulter, Inc.) Aperture diameter: 100μm Analysis software: Multisizer III version 3.51 (Beckman Coulter, Inc.) Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) Dispersion liquid: Polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Griffin) = 13.6) was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of the measurement sample is added to 5 mL of the dispersion liquid, and dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W). Then, 25 mL of electrolyte is added, and the mixture is further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid. Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles could be measured in 20 seconds. Then, 30,000 particles were measured, and the volume median particle size (D 50 ) is required.

[0145] Resin manufacturing example 1 The raw material monomers of polyester resin other than trimellitic anhydride and the esterification catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensation was carried out at 235°C for 6 hours. The temperature was then lowered to 210°C, and trimellitic anhydride shown in Table 1 was added, and the reaction was carried out at 210°C for 1 hour, and then the reaction was further carried out at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain an amorphous polyester resin (resin A1). The physical properties are shown in Table 1.

[0146] Resin manufacturing example 2 The raw material monomers and esterification catalyst for the polyester resin shown in Table 1 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, after which polycondensation was carried out at 235°C for 6 hours. The reaction was then carried out at 235°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain an amorphous polyester resin (resin A2). The physical properties are shown in Table 1.

[0147] Resin manufacturing example 3 The raw material monomers and esterification catalyst for the polyester resin shown in Table 1 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, after which polycondensation was carried out at 235°C for 6 hours. The reaction was then carried out at 235°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain an amorphous polyester resin (resin A3). The physical properties are shown in Table 1.

[0148] Resin manufacturing example 4 The raw material monomers of polyester resin other than adipic acid and trimellitic anhydride shown in Table 1 and the esterification catalyst were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensation was carried out at 235°C for 6 hours. The temperature was then lowered to 210°C, and adipic acid and trimellitic anhydride shown in Table 1 were added, and the reaction was carried out at 210°C for 1 hour, and then the reaction was further carried out at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain an amorphous polyester resin (resin A4). The physical properties are shown in Table 1.

[0149] Resin manufacturing example 5 The raw material monomers of polyester resin other than trimellitic anhydride shown in Table 1 and the esterification catalyst were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stainless steel stirring rod and a thermocouple, and reacted in a mantle heater under a nitrogen atmosphere at normal pressure and 230 ° C for 12 hours, and then the reaction was continued for 1 hour while maintaining 230 ° C and reducing the pressure to 8.3 kPa. Thereafter, the pressure was returned to normal and the temperature was lowered to 160 ° C, and the raw material monomers of the styrene-based resin shown in Table 1, the bireactive monomers and the polymerization initiator were individually and simultaneously dropped over 1 hour using a dropping funnel. After maturing the addition polymerization reaction for 1 hour while maintaining the temperature at 160 ° C, the temperature was raised to 210 ° C, the pressure was reduced to 8.3 kPa, and the unreacted raw material monomers of the styrene-based resin were removed for 1 hour while maintaining the temperature at 210 ° C. Furthermore, the pressure was returned to normal, and trimellitic anhydride shown in Table 1 was added at 210 ° C, and the reaction was continued until the desired softening point was reached, to obtain an amorphous composite resin (resin A5). The physical properties of the obtained resin are shown in Table 1.

[0150] [Table 1]

[0151] Resin manufacturing example 6 The raw material monomers and esterification catalyst of the polyester resin shown in Table 2 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stainless steel stirring rod, and a thermocouple, and heated to 160°C at normal pressure in a mantle heater under a nitrogen atmosphere and reacted for 6 hours. Then, the raw material monomers of the styrene resin shown in Table 2, the bireactive monomers, and the polymerization initiator were individually and simultaneously dropped over 1 hour using a dropping funnel. After maturing the addition polymerization reaction for 1 hour while maintaining the temperature at 160°C, the pressure was reduced to 8.3 kPa and the raw material monomers of the styrene resin were removed for 1 hour. Furthermore, the temperature was raised to 200°C over 8 hours, and the reaction was carried out at 8.3 kPa for 2 hours to obtain crystalline composite resins (resins C1 and C2). The physical properties of the obtained resins are shown in Table 2.

[0152] Resin manufacturing example 7 The raw material monomers for the polyester resin shown in Table 2 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the temperature was raised to 200°C over 8 hours in a nitrogen atmosphere in a mantle heater. Then, the esterification catalyst shown in Table 2 was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 2 was reached, obtaining a crystalline polyester resin (resin C3). The physical properties are shown in Table 2.

[0153] [Table 2]

[0154] Examples 1 to 8, 11 and Comparative Examples 3, 4, 6 to 8 100 parts by mass of the binder resin shown in Table 3, 1.0 part by mass of a negatively charged charge control agent "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), 6.0 parts by mass of carbon black "Mougul-L" (manufactured by Cabot Specialty Chemicals, Inc.), 4.0 parts by mass of carnauba wax (manufactured by Kato Yoko Co., Ltd., carnauba wax "No. 1", melting point 85°C), and 3.0 parts by mass of paraffin wax (manufactured by Nippon Seiro Co., Ltd., HNP-9, melting point: 75°C) were mixed and stirred for 2 minutes in a Henschel mixer, and then melt-kneaded under the conditions shown below using a continuous two-roll open-roll kneader "Kneedex" (manufactured by Mitsui Mining Co., Ltd., roll outer diameter: 13.8 cm, effective roll length: 63.2 cm).

[0155] When the raw materials were fed, the peripheral speeds of the front roll and the back roll were both set to 32.50 m / min (rotation speed: 75 m / min) and kneading was started. When the filling rate of the raw materials fed into the kneader reached the filling rate shown in Table 3, the peripheral speed of the back roll was changed to 21.67 m / min (rotation speed: 50 r / min) and kneading was continued. The roll gap was 0.1 mm. The heating medium temperature and the cooling medium temperature in the roll were 130°C on the raw material feeding side of the front roll and 90°C on the kneaded material discharge side, and 35°C on the raw material feeding side of the back roll and 35°C on the kneaded material discharge side. The feed rate of the raw material mixture was 10 kg / h, and the total amount of raw materials fed was 10 kg. In addition, in calculating the filling rate, the density of the raw materials for volume conversion was 1.2 (g / cm 3 ), and the surface area of ​​the roll is 2738.5824 (cm 2 ) and the roll gap was 0.1 (mm).

[0156] The obtained molten mixture was cooled to below 20°C while being rolled with a cooling roll, and the cooled molten mixture was coarsely pulverized to 3 mm using a Rotoplex (manufactured by Toa Machinery Co., Ltd.). Thereafter, it was pulverized and classified using a fluidized bed jet mill "200 type AFG" (manufactured by Hosokawa Micron Corporation) and a rotary air classifier "100TTSP" (manufactured by Hosokawa Micron Corporation) to obtain the volume median particle size (D 50 ) yielded 6 μm toner particles.

[0157] 100 parts by weight of the obtained toner particles and 1.5 parts by weight of hydrophobic silica "RY50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, average particle size: 40 nm) and 0.7 parts by weight of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) as external additives were mixed in a Henschel mixer for 3 minutes to obtain a toner.

[0158] Examples 9 and 10 A toner was obtained in the same manner as in Example 1, except that the binder resin shown in Table 3, 1.0 part by mass of a negatively charged charge control agent "Bontron E-84" (manufactured by Orient Chemical Industry Co., Ltd.), 5.0 parts by mass of a colorant "ECB-301" (manufactured by Dainichi Seikagaku Co., Ltd., phthalocyanine blue (PB15:3)), 4.0 parts by mass of carnauba wax (manufactured by Kato Yoko Co., Ltd., carnauba wax "No. 1", melting point: 85°C), and 3.0 parts by mass of paraffin wax (manufactured by Nippon Seiro Co., Ltd., HNP-9, melting point: 75°C) were used, and that the filling rate when changing the peripheral speed in the melt-kneading process was 1.4 or 1.6.

[0159] Example 12 A toner was obtained in the same manner as in Example 1, except that in the melt-kneading step, the filling rate when the peripheral speed was changed was 1.6, and the peripheral speed of the back roll at the start of kneading was changed to 31.63 m / min (rotation speed: 73 r / min).

[0160] Example 13 A toner was obtained in the same manner as in Example 1, except that in the melt-kneading step, the filling rate when the peripheral speed was changed was 1.8, and the peripheral speed of the back roll at the start of kneading was changed to 30.33 m / min (rotation speed: 70 r / min).

[0161] Example 14 A toner was obtained in the same manner as in Example 1, except that in the melt-kneading process, the filling rate when the peripheral speed was changed was 1.5, and the peripheral speed of the back roll after the change during kneading was changed to 10.83 m / min (rotation speed: 25 r / min).

[0162] Example 15 A toner was obtained in the same manner as in Example 1, except that in the melt-kneading process, the filling rate when the peripheral speed was changed was 1.4, the peripheral speed of the back roll at the start of kneading was changed to 30.33 m / min (rotation speed: 70 r / min), and the peripheral speed of the back roll after the change during kneading was changed to 10.83 m / min (rotation speed: 25 r / min).

[0163] Comparative Example 1 In the melt kneading process, the peripheral speed of the front roll was set to 32.50 m / min (rotation speed: 75 m / min), the peripheral speed of the back roll was set to 21.67 m / min (rotation speed: 50 r / min), and kneading was started. A toner was obtained in the same manner as in Example 1, except that the rotation speed of the back roll was not changed during kneading.

[0164] Comparative Example 2 In the melt kneading process, the peripheral speeds of the front roll and back roll were both set to 32.50 m / min (rotation speed: 75 m / min) and kneading was started, and the rotation speed of the back roll was not changed during the kneading process. A toner was obtained in the same manner as in Example 1.

[0165] Comparative Example 5 A toner was obtained in the same manner as in Example 1, except that the peripheral speed of the back roll at the start of kneading was changed to 28.17 m / min (rotation speed: 65 r / min).

[0166] Test Example 1 [Low temperature fixability] The toner was installed in a non-magnetic single-component developing device "OKI COREFIDO C712dnw" (manufactured by Oki Electric Industry Co., Ltd.) and the toner adhesion amount was set to 0.50 mg / cm 2The temperature was adjusted to 100° C., and a 20 mm×30 mm solid image was printed on “Color Copy 90 Paper” (manufactured by Fuji Xerox Office Supply Co., Ltd.), and the solid image was removed before passing through the fixing machine to obtain an unfixed image. The paper with the obtained unfixed image was fixed at a fixing speed of 150 mm / sec in an external fixing machine modified from the fixing machine of a non-magnetic one-component developing device “OKI MICROLINE 3020c” (manufactured by Oki Electric Industry Co., Ltd.) with the fixing roll temperature set to 110° C. After that, the fixing roll temperature was set to 115° C., and the same operation was performed. The temperature was increased by 5° C. at each temperature up to 200° C., and the unfixed image was fixed at each temperature to obtain a fixed image. A white "L paper" (Xerox) was wrapped around a 1000g weight with a bottom surface of 50φ, and the weight was placed on the image obtained at each fixing temperature. The weight was then moved back and forth five times across the width of the image, and the image density before and after rubbing was measured using an image densitometer "SPM-50" (Gretag). The temperature of the fixing roll at which the ratio before and after rubbing ([image density after rubbing / image density before rubbing] x 100) first exceeded 90% was taken as the minimum fixing temperature, and low-temperature fixing ability was evaluated. The lower the minimum fixing temperature, the better the low-temperature fixing ability. The results are shown in Table 3.

[0167] Test Example 2 [High-temperature offset resistance] The images fixed at 100°C to 200°C obtained in Test Example 1 were visually inspected, and the highest fixing roll temperature at which no hot offset was observed was taken as the maximum fixing temperature, and high-temperature offset resistance was evaluated. The higher the maximum fixing temperature, the better the high-temperature offset resistance. The results are shown in Table 3. In the table, "200<" indicates that no hot offset was observed in the images fixed at 200°C.

[0168] Test Example 3 [Fogging evaluation in a low temperature and low humidity environment (LL)] The toner was mounted on an OKI COREFIDO C712dnw printer manufactured by Oki Electric Industry Co., Ltd., and 2,000 sheets were printed at a print rate of 1% at normal temperature and humidity of 23°C and 50%, after which the printer was left overnight at a temperature of 10°C and a relative humidity of 20%, after which blank printing was performed, during which the printer was stopped midway through printing the blank sheet. The developing unit was removed from the printer, and Scotch (registered trademark) Mending Tape 810 (manufactured by 3M Japan Ltd., width: 18 mm) was attached to the photoconductor, and the toner on the photoconductor was peeled off with the tape. The tape peeled off from the photoreceptor and unused tape were attached to high-quality paper "Excellent White Paper A4 Size" (manufactured by Oki Data Corporation), and the tape peeled off from the photoreceptor and unused tape were each measured using a colorimeter "SpectroEye" (manufactured by GretagMacbeth, light irradiation conditions: standard light source D50, observation field of view 2°, density standard DINNB, absolute white standard). The color difference (ΔE) between the tape peeled off from the photoreceptor and unused tape was calculated as fog. The smaller the fog value, the better the image without fog. The results are shown in Table 3.

[0169] [Table 3]

[0170] From the above results, it is clear that in Examples 1 to 15, toners that achieve both low-temperature fixability and high-temperature offset resistance can be obtained, and fogging under low-temperature and low-humidity conditions can also be suppressed. In contrast, a comparison between Comparative Examples 1 to 5 and Example 1 shows that the operating conditions of the continuous two-roll open-roll type kneader have a significant effect on the suppression of fogging under low temperature and low humidity conditions. Also, a comparison between Comparative Examples 6 to 8 and Example 1 shows that by using a predetermined amount of an amorphous polyester resin having a predetermined storage modulus, fogging under low temperature and low humidity conditions can be suppressed while low temperature fixability is improved. [Industrial Applicability]

[0171] The toner for developing electrostatic images obtained by the method of the present invention is suitably used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing and the like.

Claims

1. A method for producing a toner for developing electrostatic images, the method comprising the step of melting and kneading raw materials containing a binder resin using a continuous two-open roll kneader, wherein the binder resin contains 20% by mass or more and 80% by mass or less of an amorphous polyester resin having a storage modulus of 30,000 Pa or less at 100°C, and wherein, when a peripheral speed of a front roll of the kneader is Vf and a peripheral speed of a back roll is Vb, a difference rate ΔV between the peripheral speeds of the two rolls calculated from 100 × (Vf - Vb) / Vf is Formula (A): 0≦ΔV ０ ≦10, and Formula (B): ΔV １ -ΔV ０ > 0 (In the formula, ΔV ０ is ΔV at the start of raw material input, ΔV １ indicates the changed ΔV) and changing the packing ratio of the raw materials fed into the kneader within a range of 1.0 to 5.0 so as to satisfy the above.

2. Formula (B) is ΔV １ -ΔV ０ ≧10.

3. Formula (B) is ΔV １ -ΔV ０ 75% or less of the total mass of the polymers in the process of claim 1 .

4. ΔV １ The method according to claim 1, wherein the value of β is 20 or more.

5. The method according to claim 1 , wherein the binder resin further contains 1% by mass or more and 40% by mass or less of a crystalline polyester resin.