Method for producing electrostatic latent image developing toner

Abstract

A method for producing an electrostatic latent image developing toner includes: aggregating and combining material particles including polyester resin particles containing a colorant in a dispersion medium to obtain toner particles, the method for producing the electrostatic latent image developing toner includes a step for producing the polyester resin particles containing the colorant, and the step for producing the polyester resin particles containing the colorant includes: obtaining a mixture by mixing an alkaline colorant and a polyester resin while applying heat to the alkaline colorant and the polyester resin; and emulsifying the mixture, and in the step of manufacturing the polyester resin particles containing the colorant, the time weighted average T DEG C of the temperature of the polyester resin and the time R second during which the temperature of the polyester resin is in the range of 35 DEG C to 100 DEG C satisfy the relationship 200 < = (T * lnR) < = 550.

Description

Technical Field

[0001] The present invention relates to a method for producing a toner for developing electrostatic latent images. Background Art

[0002] Patent Document 1 discloses an emulsion composition containing an emulsified polymer and a dye and being dyed, wherein the emulsified polymer is obtained by emulsifying and polymerizing a monomer mixture containing a vinyl monomer (A) having a cyano group, a vinyl monomer (B) having an acidic functional group, and other vinyl monomers (C) in the presence of an anionic surfactant (D).

[0003] Patent document 2 discloses a method for producing a toner, which includes: (A) a mixing step of mixing a binder resin containing a polyester having an acid group, a colorant, an alkaline substance and a surfactant in an aqueous medium to obtain a mixture; (B) a melt emulsification step of applying a shear force while heating the mixture to a temperature 10°C higher than the softening temperature Tm of the binder resin to obtain a molten emulsion; (C) a cooling step of applying a shear force to the molten emulsion at a cooling rate of 0.5°C / min to 10°C / min to a temperature below the glass transition temperature Tg of the binder resin to produce a microparticle dispersion having a median particle size of 1.0 μm or less; and (D) a step of agglomerating the microparticle dispersion in an aqueous medium.

[0004] Patent document 3 discloses a resin particle containing a polyester resin and a basic dye, wherein the volume average particle size of the resin particle is greater than or equal to 0.05 μm and less than or equal to 1 μm, and the concentration ratio of the basic dye in the center of gravity portion of the resin particle relative to the surface portion at a depth of less than 10 nm from the surface of the resin particle is greater than 0.8.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-010846

[0006] Patent Document 2: Japanese Patent Application Publication No. 2010-276750

[0007] Patent Document 3: Japanese Patent Application Publication No. 2021-127428 Summary of the invention

[0008] An object of the present invention is to provide a method for producing a toner for developing an electrostatic latent image which suppresses the occurrence of uneven image density and has excellent heat storage properties.

[0009] Specific means for solving the above-mentioned problems include the following aspects.

[0010] <1>

[0011] A method for producing a toner for electrostatic latent image development, comprising the steps of aggregating and combining material particles including polyester resin particles containing a colorant in a dispersion medium to obtain toner particles, the method for producing a toner for electrostatic latent image development comprising a step of producing the polyester resin particles containing a colorant,

[0012] The process for producing the colorant-containing polyester resin particles comprises the steps of: mixing a basic colorant and a polyester resin while applying heat to obtain a mixture; and emulsifying the mixture.

[0013] In the process of producing the colorant-containing polyester resin particles, the time-weighted average T°C of the temperature of the polyester resin and the time R seconds during which the temperature of the polyester resin is within the range of 35°C to 100°C satisfy the relationship of 200≤(T×lnR)≤550.

[0014] <2>

[0015] The method for producing a toner for developing an electrostatic latent image according to <1>, wherein:

[0016] In the entire process of producing the colorant-containing polyester resin particles, the temperature of the polyester resin is within a range of 35° C. to 100° C.

[0017] <3>

[0018] The method for producing a toner for developing an electrostatic latent image according to <1> or <2>, wherein:

[0019] In the production process of the colorant-containing polyester resin particles, no organic solvent is used.

[0020] <4>

[0021] The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <3>, wherein:

[0022] The basic colorant includes a basic dye.

[0023] <5>

[0024] The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <4>, wherein:

[0025] The polyester resin includes an amorphous polyester resin.

[0026] <6>

[0027] The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <5>, wherein

[0028] The mass ratio of the basic colorant to the polyester resin contained in the colorant-containing polyester resin particles is basic colorant:polyester resin=0.1:99.9 to 20:80.

[0029] <7>

[0030] The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <6>, wherein:

[0031] The volume average particle diameter of the colorant-containing polyester resin particles is 50 nm or more and 500 nm or less.

[0032] Effects of the Invention

[0033] According to <1>, <2>, <3>, <4>, <5>, <6> or <7>, a method for producing a toner for electrostatic latent image development which suppresses the occurrence of image density unevenness and has excellent thermal storage properties compared to the case where the value of (T×lnR) is less than 200 or exceeds 550. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present invention will be described. These descriptions and examples are for illustrating the embodiments and do not limit the scope of the embodiments.

[0035] In the present invention, a numerical range expressed using "to" indicates a range including the numerical values ​​before and after "to" as the minimum value and the maximum value, respectively.

[0036] In the numerical ranges recorded in stages in the present invention, the upper limit or lower limit recorded in one numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. And, in the numerical ranges recorded in the present invention, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiment.

[0037] In the present invention, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process can be achieved.

[0038] In the present invention, each component may contain a plurality of corresponding substances. When the amount of each component in the composition is mentioned in the present invention, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of the plurality of substances present in the composition.

[0039] In the present invention, multiple types of particles corresponding to each component may be contained. When multiple types of particles corresponding to each component are present in the composition, unless otherwise specified, the particle size of each component represents a value for a mixture of the multiple types of particles present in the composition.

[0040] In the present invention, “(meth)acrylic acid” is an expression including both acrylic acid and methacrylic acid, and “(meth)acrylate” is an expression including both acrylate and methacrylate.

[0041] In the present invention, “toner” means “toner for electrostatic latent image development”, “developer” means “electrostatic latent image developer”, and “carrier” means “carrier for electrostatic latent image development”.

[0042] In the present invention, a method of producing toner particles by aggregating and combining material particles in a dispersion medium is referred to as an EA (Emulsion Aggregation) method.

[0043] <Method for producing toner for developing electrostatic latent images>

[0044] The method for producing a toner according to the present embodiment includes a step of producing toner particles by the EA method.

[0045] In the method for producing a toner according to the present embodiment, at least polyester resin particles containing a colorant are used as material particles.

[0046] Therefore, the method for producing a toner according to the present embodiment includes the step of aggregating and combining material particles including polyester resin particles containing a colorant in a dispersion medium to obtain toner particles.

[0047] Specifically, the method for producing a toner according to the present embodiment includes a step of producing polyester resin particles containing a colorant.

[0048] The process for producing polyester resin particles containing a colorant comprises the steps of: mixing a basic colorant and a polyester resin while applying heat to obtain a mixture; and emulsifying the mixture.

[0049] In the production process of the colorant-containing polyester resin particles, the time-weighted average T°C of the polyester resin temperature and the time R seconds during which the polyester resin temperature is within the range of 35°C to 100°C satisfy the relationship 200≤(T×lnR)≤550.

[0050] In the process of producing polyester resin particles containing a colorant, the temperature of the polyester resin may be constant or may vary. When the temperature of the polyester resin varies, there may be a time when the temperature is less than 35° C. or a time when the temperature exceeds 100° C. However, in the entire process of producing polyester resin particles containing a colorant, the temperature of the polyester resin is preferably within a range of, for example, 35° C. to 100° C.

[0051] The time-weighted average T°C of the temperature of the polyester resin is a value obtained by weighting the temperature of the polyester resin during the production process of the colorant-containing polyester resin particles according to the time the temperature continues and averaging the values.

[0052] lnR is the natural logarithm of R.

[0053] According to the method for producing a toner according to the present embodiment, a toner which suppresses the occurrence of uneven image density and has excellent heat storage properties can be produced. The mechanism is estimated as follows.

[0054] As a method for stably manufacturing toner particles with a particle size of several μm, the EA method is known. However, depending on the type of material used in the EA method, it is sometimes difficult for the material particles to be evenly dispersed with each other, and sometimes a specific material inside the toner particle forms a block and is unevenly distributed. In the toner and developer containing such toner particles, charge leakage is easily caused, and sometimes uneven image density occurs. For example, when polyester resin particles and alkaline colorant particles are used as material particles of the EA method, sometimes the alkaline colorant forms a block and is unevenly distributed inside the toner particle, and sometimes uneven image density occurs.

[0055] In the present embodiment, as a countermeasure to suppress the above phenomenon, the basic colorant particles as the material particles of the EA method are made to contain not only the basic colorant but also a polyester resin, thereby suppressing the basic colorant from agglomerating and unevenly distributed inside the toner particles.

[0056] Then, in the present embodiment, in the manufacturing process of the polyester resin particles containing the colorant, the temperature and heating time to which the polyester resin is exposed are controlled. The polyester resin is easily hydrolyzed by the action of the alkaline colorant, and the hydrolysis of the polyester resin is suppressed by controlling the temperature and time of the manufacturing process of the polyester resin particles containing the colorant. As a result, the molecular weight of the polyester resin can be maintained, and even when the manufactured toner is left for a long time at high temperature, the toner is not easily aggregated.

[0057] In the production process of the polyester resin particles containing the colorant, from the viewpoint of improving the dispersibility of the basic colorant, for example, the temperature of the dispersion liquid in the granulation is preferably high. On the other hand, the higher the temperature of the dispersion liquid in the granulation, the easier it is for the hydrolysis of the polyester resin to proceed. In the present embodiment, in the production process of the polyester resin particles containing the colorant, the time-weighted average T°C of the temperature of the polyester resin and the time R seconds in which the temperature of the polyester resin is within the range of 35°C or more and 100°C or less are controlled to satisfy the relationship of 200≤(T×lnR)≤550.

[0058] If (T×lnR) is less than 200, the basic colorant is insufficiently dispersed in the polyester resin, and uneven image density may occur. To suppress this, (T×lnR) is 200 or more, for example, preferably 250 or more, and more preferably 300 or more.

[0059] If (T×lnR) exceeds 550, hydrolysis of the polyester resin may progress, and the heat-resistant storage stability of the produced toner may be deteriorated. In order to suppress this, (T×lnR) is 550 or less, for example, preferably 500 or less, and more preferably 450 or less.

[0060] From the viewpoint of controlling (T×lnR) within the above range, in the overall manufacturing process of the polyester resin particles containing the colorant, the temperature of the polyester resin is, for example, preferably in the range of 35°C to 100°C, more preferably in the range of 38°C to 98°C, and further preferably in the range of 40°C to 95°C.

[0061] Specifically, in the present embodiment, the production of toner particles by the EA method preferably includes, for example:

[0062] an agglomeration step of agglomerating the material particles in the dispersion containing the material particles to form agglomerated particles; and

[0063] In the agglomeration step, the dispersion liquid containing the aggregated particles is heated to fuse the aggregated particles into a body to form toner particles.

[0064] Then, the material particles include colorant-containing polyester resin particles containing a basic colorant and a polyester resin.

[0065] Hereinafter, the production process of the colorant-containing polyester resin particles in the present embodiment, each process of the EA method, and materials will be described in detail.

[0066] [Process for producing polyester resin particles containing colorant]

[0067] The production process of the colorant-containing polyester resin particles includes the steps of: mixing a basic colorant and a polyester resin while applying heat to obtain a mixture; and emulsifying the mixture.

[0068] From the viewpoint that the basic colorant is easily and uniformly present inside the colorant-containing polyester resin particles and inside the toner particles, the mass ratio of the basic colorant to the polyester resin contained in the colorant-containing polyester resin particles is, for example, preferably basic colorant:polyester resin=0.1:99.9 to 20:80, more preferably 0.5:99.5 to 15:85, and even more preferably 1:99 to 10:90.

[0069] From the viewpoint of being easily uniformly dispersed and aggregated in the aggregation step of the EA method, the volume average particle size of the colorant-containing polyester resin particles is, for example, preferably 50 nm to 500 nm, more preferably 65 nm to 400 nm, and further preferably 80 nm to 300 nm.

[0070] The volume average particle size of the polyester resin particles containing the colorant refers to the particle size at which the cumulative total from the small diameter side reaches 50% in the particle size distribution measured by a laser diffraction particle size distribution analyzer (e.g., model: LS13-320, Beckman Coulter, Inc.). The number of particles measured is 10,000.

[0071] -Alkaline colorant-

[0072] The basic coloring agent may be used alone or in combination of two or more.

[0073] Examples of the basic colorant include basic dyes and basic pigments. As the basic colorant, only a basic dye may be used, only a basic pigment may be used, or both a basic dye and a basic pigment may be used.

[0074] As the basic colorant, a fluorescent colorant can be mentioned. As the basic colorant, only a non-fluorescent colorant may be used, only a fluorescent colorant may be used, or both a non-fluorescent colorant and a fluorescent colorant may be used.

[0075] Examples of basic dyes include dioxazine dyes, oxazine dyes, thiazine dyes, azo dyes, anthraquinone dyes, xanthene dyes, triarylmethane dyes, phthalocyanine dyes, auramine dyes, acridine dyes, and formazan dyes. Specifically, the following dyes are included.

[0076] Basic Red 2, 5, 6, 10, Basic Blue 13, 14, 16, Basic Violet 5, 6, 8, 12, Basic Yellow 14 and other diazines; Basic Blue 3, 6, 10, 12, 74 and other oxazine dyes; Basic Blue 9, 17, 24, 25, Basic Green 5 and other thiazine dyes; Basic Red 18, 22, 23, 24, 29, 30, 31, 32, 34, 38, 39, 46, 51, 53, 54, 55 5, 62, 64, 76, 94, 111, 118, basic blue 41, 53, 54, 55, 64, 65, 66, 67, 162, basic violet 18, 36, basic yellow 15, 19, 24, 25, 28, 29, 38, 39, 49, 51, 57, 62, 73, basic orange 1, 2, 24, 25, 29, 30, 33, 54, 69 and other azo dyes; basic blue 22, Anthraquinone dyes such as 44, 47, 72; xanthene dyes such as basic red 1, 1:1, 3, 4, 8, 11, basic violet 10, 11, 11:1; triarylmethane dyes such as basic red 9, basic blue 1, 2, 5, 7, 8, 11, 15, 18, 20, 23, 26, 35, 81, basic violet 1, 2, 3, 4, 14, 23, basic green 1, 4; phthalocyanine dyes such as basic blue 140; basic yellow Auramine dyes such as 2, 3, 37; acridine dyes such as basic yellow 5, 6, 7, 9, basic orange 4, 5, 14, 15, 16, 17, 18, 19, 23; methamine dyes such as basic red 12, 13, 14, 15, 27, 28, 37, 52, 90, basic yellow 11, 13, 20, 21, 52, 53, basic orange 21, 22, basic violet 7, 15, 16, 20, 21, 22.

[0077] Examples of the basic pigment include azo pigments and quinacridone pigments. Specifically, the following pigments are included.

[0078] Azo pigments such as Pigment Red 146, 166, Pigment Yellow 1, 13, 74, 83, 180; Quinacridone pigments such as Pigment Orange 48, 49, Pigment Red 122, 202, 206, 207, 209, Pigment Violet 19

[0079] As the fluorescent basic coloring agent, from the viewpoint of fluorescence intensity, for example, Basic Red 1 (Rhodamine 6G), Basic Red 1:1, Basic Red 2, Basic Red 12, Basic Red 13, Basic Red 14, Basic Red 15, Basic Red 36, Basic Violet 7, Basic Violet 10 (Rhodamine B), Basic Violet 11 (Rhodamine 3B), Basic Violet 11:1 (Rhodamine A), Basic Violet 15, Basic Violet 16, Basic Violet 27, Basic Yellow 1, Basic Yellow 2, Basic Yellow 9, Basic Yellow 24 ... Yellow 40, basic orange 15, basic orange 22, basic blue 1, basic blue 3, basic blue 7, basic blue 9, basic blue 45, basic green 1, more preferably basic red 1 (rhodamine 6G), basic red 1:1, basic red 2, basic red 12, basic red 13, basic red 14, basic red 15, basic red 36, basic violet 7, basic violet 10 (rhodamine B), basic violet 11 (rhodamine 3B), basic violet 11:1 (rhodamine A), basic violet 15, basic violet 16, basic violet 27.

[0080] -Polyester resin-

[0081] As the polyester resin, there are amorphous polyester resins and crystalline polyester resins. As the polyester resin, only amorphous polyester resins may be used, only crystalline polyester resins may be used, or both amorphous polyester resins and crystalline polyester resins may be used. As the polyester resin, for example, amorphous polyester resins are preferred.

[0082] -Amorphous polyester resin-

[0083] As the amorphous polyester resin, a commercially available product may be used, or a synthetic product may be used.

[0084] Examples of the non-crystalline polyester resin include polycondensates of polycarboxylic acids and polyols.

[0085] Examples of the polycarboxylic acid as a polymerization component of the amorphous polyester resin include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexane dicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), and anhydrides thereof or lower (e.g., carbon number 1 to 5) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as the polycarboxylic acid.

[0086] The polycarboxylic acid may be used together with the dicarboxylic acid in a trivalent or higher carboxylic acid having a cross-linked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0087] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0088] Examples of the polyol as a polymerization component of the amorphous polyester resin include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-docosanediol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, as the polyol, for example, aliphatic diol is preferable.

[0089] As the polyol as the polymerization component of the amorphous polyester resin, a trivalent or higher polyol having a crosslinked structure or a branched structure may be used together with a diol. Examples of the trivalent or higher polyol include glycerol, trimethylolpropane, and pentaerythritol.

[0090] The polyols may be used alone or in combination of two or more.

[0091] The glass transition temperature (Tg) of the amorphous polyester resin is, for example, preferably 50°C to 75°C, more preferably 50°C to 70°C, and further preferably 50°C to 65°C.

[0092] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, according to the "extrapolated glass transition start temperature" described in the method for determining the glass transition temperature in JIS K7121-1987 "Determination of Transition Temperature of Plastics".

[0093] The weight average molecular weight (Mw) of the amorphous polyester resin is, for example, preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.

[0094] The number average molecular weight (Mn) of the amorphous polyester resin is preferably, for example, 2,000 or more and 100,000 or less.

[0095] The molecular weight distribution Mw / Mn of the amorphous polyester resin is, for example, preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0096] The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). In the molecular weight measurement by GPC, GPC HLC-8120GPC manufactured by TOSOH CORPORATION is used as a measuring device, and a column TSKgel SuperHM-M (15 cm) manufactured by TOSOH CORPORATION is used, and the solvent is THF. The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample based on the measurement results.

[0097] The acid value of the amorphous polyester resin is, for example, preferably 1 mgKOH / g to 50 mgKOH / g, more preferably 3 mgKOH / g to 30 mgKOH / g, and further preferably 5 mgKOH / g to 18 mgKOH / g.

[0098] The acid value of the non-crystalline polyester resin is determined by a neutralization titration method specified in JIS K0070-1992 using an appropriate amount of the non-crystalline polyester resin as a sample.

[0099] The amorphous polyester resin is obtained by a known production method. Specifically, for example, the amorphous polyester resin is obtained by setting the polymerization temperature to 180° C. to 230° C., reducing the pressure in the reaction system as necessary, and reacting while removing water and alcohol generated during condensation.

[0100] When the monomer of the raw material is insoluble or incompatible at the reaction temperature, a high boiling point solvent can be added as a cosolvent to dissolve it. In this case, the polycondensation reaction is carried out while the cosolvent is removed by distillation. When there are monomers with poor compatibility in the copolymerization reaction, for example, the monomers with poor compatibility can be condensed in advance with an acid or alcohol to be polycondensed with the monomer, and then polycondensed with the main component.

[0101] -Crystalline polyester resin-

[0102] As the crystalline polyester resin, a commercially available product may be used, or a synthetic product may be used.

[0103] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. Since the crystalline polyester resin easily forms a crystalline structure, for example, a polycondensate of a linear aliphatic polymerizable monomer is preferably used rather than a polycondensate of a polymerizable monomer having an aromatic ring.

[0104] Examples of the polycarboxylic acid as a polymerization component of the crystalline polyester resin include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid, etc.), acid anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof.

[0105] The polycarboxylic acid may be used together with the dicarboxylic acid and a trivalent or higher carboxylic acid having a cross-linked structure or a branched structure. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0106] As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used together with these dicarboxylic acids.

[0107] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0108] Examples of the polyol as a polymerization component of the crystalline polyester resin include aliphatic diols (e.g., linear aliphatic diols having a main chain portion with carbon atoms of 7 or more and 20 or less). Examples of the aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-docosanediol.

[0109] As the polyol as the polymerization component of the crystalline polyester resin, a trivalent or higher alcohol having a cross-linked structure or a branched structure may be used together with a diol. Examples of the trivalent or higher alcohol include glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0110] The polyols may be used alone or in combination of two or more.

[0111] The melting temperature of the crystalline polyester resin is, for example, preferably 50° C. or higher and 100° C. or lower, more preferably 55° C. or higher and 90° C. or lower, and further preferably 60° C. or higher and 85° C. or lower.

[0112] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) in accordance with the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Determination of Transition Temperatures of Plastics”.

[0113] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably, for example, 6,000 or more and 35,000 or less.

[0114] Similar to the amorphous polyester resin, the crystalline polyester resin can be obtained by, for example, a known production method.

[0115] The colorant-containing polyester resin particles are preferably produced in the form of a dispersion containing the particles, for example. That is, the production process of the colorant-containing polyester resin particles is preferably a production process of a colorant-containing polyester resin particle dispersion, for example.

[0116] From the viewpoint of allowing the toner particles to contain a sufficient amount of the colorant, the solid content concentration of the polyester resin particle dispersion containing the colorant is, for example, preferably 10 mass % or more, more preferably 15 mass % or more, and even more preferably 20 mass % or more.

[0117] From the viewpoint of dispersibility of the particles, the solid content concentration of the polyester resin particle dispersion containing the colorant is, for example, preferably 50 mass % or less, more preferably 45 mass % or less, and even more preferably 40 mass % or less.

[0118] Hereinafter, “solventless emulsification” and “solvent emulsification” as embodiments of the process for producing polyester resin particles containing a colorant will be described. The solventless emulsification and the solvent emulsification produce a dispersion of polyester resin particles containing a colorant.

[0119] -Solvent-free emulsification-

[0120] The solvent-free emulsification is a method in which no organic solvent is used in the production process of the polyester resin particles containing the colorant.

[0121] Specifically, solvent-free emulsification includes:

[0122] a melting step of applying heat and shear force to the basic colorant, the polyester resin, the basic compound (however, excluding the basic colorant), and the surfactant and mixing them to obtain a mixture in which the basic colorant is dispersed in the molten polyester resin; and

[0123] In the emulsification step, an aqueous medium is added to the mixture while applying a shear force to emulsify the mixture.

[0124] In solvent-free emulsification, the time-weighted average of temperature T°C and time R seconds refers to the temperature T°C and time R seconds during the period from the start of the melting step to the end of the emulsification step.

[0125] For example, the solvent-free emulsification preferably uses a mixing extruder to perform the melting process and the emulsification process. The mixing extruder is a device that continuously conveys the processed material while applying heat and shear force to the processed material. Generally speaking, the structure of the mixing extruder is roughly divided into a material input port, a barrel, and a mold from upstream to downstream. A screw is provided inside the barrel. A heater for heating the inside of the barrel is provided around the barrel. The screw can be a single screw type or a twin screw type, and is preferably a twin screw type.

[0126] As the alkaline compound, for example, sodium hydroxide or potassium hydroxide is preferred. From the viewpoint of uniformity of kneading, sodium hydroxide or potassium hydroxide is preferably used in the form of an aqueous solution (ie, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution).

[0127] The amount of the basic compound used is an amount that enables emulsification and dispersion of the mixture. Specifically, the amount of the basic compound used is preferably an amount such that the neutralization rate based on the following formula (1) is 30% or more and 80% or less.

[0128] Formula (1): Neutralization rate (%) = mb × n × 56.1 ÷ Mwb ÷ AV × 1000,

[0129] mb is the amount of the basic compound used per 1g of polyester resin (g),

[0130] n is the valence of the basic compound,

[0131] Mwb is the molecular weight of the basic compound,

[0132] AV is the acid value of the polyester resin (mgKOH / g).

[0133] The surfactant may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. For example, anionic surfactants such as sulfate ester salts, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols; etc. Surfactants may be used alone or in combination of two or more. Nonionic surfactants may be used together with anionic surfactants or cationic surfactants.

[0134] The amount of the surfactant used is set to an amount that allows the emulsified particles to maintain dispersion.

[0135] The aqueous medium is preferably water with reduced ion content such as distilled water or deionized water. The aqueous medium is preferably used at a temperature of 35°C to 100°C, more preferably within the range of ±5°C of the barrel internal temperature of the kneading extruder.

[0136] In the melting step, the temperature inside the barrel of the kneading extruder is, for example, preferably 80° C. or higher and 110° C. or lower, more preferably 85° C. or higher and 105° C. or lower, and further preferably 90° C. or higher and 100° C. or lower.

[0137] In the emulsification step, the temperature inside the barrel of the kneading extruder is, for example, preferably 80° C. or higher and 110° C. or lower, more preferably 85° C. or higher and 105° C. or lower, and further preferably 90° C. or higher and 100° C. or lower.

[0138] When a twin-screw kneading extruder is used, the average feed rate of the mixture fed from the melting step to the emulsification step is preferably 0.15 kg / (h·cm) obtained by dividing the feed rate (kg / h) by the cube of the shaft diameter (cm). 3 ) and above 3.0kg / (h·cm 3 ) or less, more preferably 0.5 kg / (h·cm 3 ) and above and 2.5kg / (h·cm 3 ) or less, more preferably 0.8 kg / (h·cm 3 ) and above 2.0kg / (h·cm 3 )the following.

[0139] The L / D (ratio of screw length L to screw diameter D) of the kneading extruder is, for example, preferably 30 to 90, more preferably 40 to 80, and even more preferably 50 to 70 in the entire melting step and emulsification step.

[0140] -Solvent emulsification-

[0141] Specifically, solvent emulsification includes:

[0142] a dissolving step of mixing the basic colorant, the polyester resin, and the organic solvent capable of dissolving the polyester resin while applying heat, so that the polyester resin is dissolved in the organic solvent and the basic colorant is dissolved or dispersed in the organic solvent to obtain a mixture; and

[0143] In the emulsification step, after adding the basic compound to the mixture, an aqueous medium is added to disperse the mixture in the aqueous medium in the form of particles.

[0144] In solvent emulsification, the time-weighted average of temperature T°C and time R seconds refers to the temperature T°C and time R seconds from the start of the dissolution step to the end of the emulsification step.

[0145] The solvent emulsification is preferably carried out in a stirring tank having a stirring member and a heating and cooling member. The stirring member is preferably a stirring member having a rotating shaft and stirring blades. The heating and cooling member is preferably a member that applies and / or removes heat from the wall of the stirring tank.

[0146] Examples of the organic solvent capable of dissolving the polyester resin include ethyl acetate, isopropyl alcohol, 2-butanol, methyl ethyl ketone, and mixed solvents thereof, of which an organic solvent or mixed solvent having a boiling point of 60° C. or higher and less than 100° C. is preferred.

[0147] As the basic compound, for example, aqueous ammonia is preferred.

[0148] The amount of the basic compound used is an amount that enables emulsification and dispersion of the mixture. Specifically, the amount of the basic compound used is preferably an amount such that the neutralization rate based on the following formula (1) is 50% or more and 100% or less.

[0149] Formula (1): Neutralization rate (%) = mb × n × 56.1 ÷ Mwb ÷ AV × 1000,

[0150] mb is the amount of the basic compound used per 1g of polyester resin (g),

[0151] n is the valence of the basic compound,

[0152] Mwb is the molecular weight of the basic compound,

[0153] AV is the acid value of the polyester resin (mgKOH / g).

[0154] The aqueous medium is preferably water with reduced ion content such as distilled water or deionized water. The aqueous medium is preferably used at a temperature adjusted to a range of 35° C. to 100° C. (for example, preferably 35° C. to 55° C.).

[0155] In the dissolving step, the temperature of the object to be treated contained in the stirring tank is, for example, preferably 25°C to 60°C, more preferably 30°C to 55°C, and further preferably 35°C to 50°C.

[0156] In the emulsification step, the temperature of the treated material contained in the stirring tank is, for example, preferably 25°C to 60°C, more preferably 30°C to 55°C, and further preferably 35°C to 50°C.

[0157] The method of adding the aqueous medium in the emulsification step is preferably dropwise addition, for example.

[0158] The time for dropping a predetermined amount (twice the amount of the resin) of the aqueous medium in the emulsification step is, for example, preferably from 10 minutes to 150 minutes, more preferably from 20 minutes to 140 minutes, and further preferably from 30 minutes to 130 minutes.

[0159] After the addition of the aqueous medium is completed, for example, preferably the inside of the stirred tank is decompressed and / or the emulsion is bubbled to remove the organic solvent. Then, in order to improve the dispersion stability of the particles, a surfactant can be added. As the surfactant, the above-mentioned anionic surfactant, cationic surfactant, and nonionic surfactant can be enumerated.

[0160] [Production process of other material particles]

[0161] As other material particles, there are binder resin particles and release agent particles. The binder resin particles are preferably manufactured in the form of a dispersion containing the binder resin particles, for example. The release agent particles are preferably manufactured in the form of a dispersion containing the release agent particles, for example.

[0162] Hereinafter, the common points between the binder resin particle dispersion and the release agent particle dispersion are collectively referred to as “particle dispersion” for explanation.

[0163] An example of an embodiment of the particle dispersion is a dispersion in which a material is dispersed in a dispersion medium in the form of particles by a surfactant.

[0164] As the dispersion medium of the particle dispersion, for example, an aqueous medium is preferred. As the aqueous medium, for example, water and alcohol can be cited. As for water, for example, distilled water, deionized water and other water with reduced ion content are preferred. These aqueous media can be used alone or in combination of two or more.

[0165] The surfactant that disperses the material in the dispersion medium may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. For example, anionic surfactants such as sulfate ester salts, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols; etc. Surfactants may be used alone or in combination of two or more. Nonionic surfactants may be used together with anionic surfactants or cationic surfactants.

[0166] Examples of a method for dispersing the material in a dispersion medium in a particle form include known dispersion methods such as a rotary shearing homogenizer, a ball mill with a medium, a sand mill, and a DYNO-MILL.

[0167] As a method for dispersing the resin in a dispersion medium in the form of particles, a phase inversion emulsification method can be cited. An example of the phase inversion emulsification method is a method in which a resin is dissolved in a hydrophobic organic solvent that can dissolve the resin, a basic compound is added to an organic continuous phase (O phase), and then an aqueous medium (W phase) is added to perform a phase inversion from W / O to O / W, thereby dispersing the resin in the form of particles in the aqueous medium.

[0168] The volume average particle size of the particles dispersed in the particle dispersion is, for example, preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, and further preferably 80 nm to 200 nm.

[0169] The volume average particle size of particles in the particle dispersion is the particle size at 50% cumulatively from the small diameter side in the particle size distribution measured by a laser diffraction particle size distribution analyzer (e.g., model: LS13-320, Beckman Coulter, Inc.) The number of particles measured is 10,000.

[0170] The content of the particles contained in the particle dispersion is, for example, preferably 5 mass % to 50 mass %, more preferably 10 mass % to 40 mass %, and further preferably 15 mass % to 30 mass %.

[0171] Hereinafter, the materials constituting the particles of each of the binder resin particle dispersion and the release agent particle dispersion will be described.

[0172] -Bonding resin-

[0173] Examples of the binder resin include vinyl resins composed of homopolymers of monomers such as styrenes (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers.

[0174] Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, and mixtures thereof with the vinyl resins or graft polymers obtained by polymerizing vinyl monomers under the coexistence of the non-vinyl resins.

[0175] These binder resins may be used alone or in combination of two or more.

[0176] As the binder resin, for example, a polyester resin is preferred. As the polyester resin, a non-crystalline polyester resin and a crystalline polyester resin can be mentioned. As the polyester resin, only a non-crystalline polyester resin can be used, only a crystalline polyester resin can be used, or both a non-crystalline polyester resin and a crystalline polyester resin can be used.

[0177] When an amorphous polyester resin is used in producing the colorant-containing polyester resin particles, for example, it is preferable that the binder resin contains an amorphous polyester resin having the same form as that of the amorphous polyester resin.

[0178] When a crystalline polyester resin is used in producing the colorant-containing polyester resin particles, for example, it is preferred that the binder resin contain a crystalline polyester resin having the same form as that of the crystalline polyester resin.

[0179] -Release agent-

[0180] Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic waxes such as montan wax, or mineral / petroleum waxes, and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited thereto.

[0181] The melting temperature of the release agent is, for example, preferably 50° C. or higher and 110° C. or lower, and more preferably 60° C. or higher and 100° C. or lower.

[0182] The melting temperature of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121:1987 "Determination of Transition Temperatures of Plastics".

[0183] [Aggregation step (first aggregating step)]

[0184] The aggregation step is a step of aggregating material particles in a dispersion liquid containing material particles to form aggregated particles.

[0185] The dispersion liquid supplied to the aggregation step contains at least polyester resin particles containing a colorant. The dispersion liquid supplied to the aggregation step preferably further contains, for example, binder resin particles and release agent particles.

[0186] When the toner production method according to the present embodiment includes the second aggregation step (a step for forming a shell) described below, the aggregation step is referred to as a “first aggregation step.” The first aggregation step is a step for forming a core in a toner having a core / shell structure.

[0187] The dispersion liquid provided in the aggregation step can be prepared by, for example, separately preparing a polyester resin particle dispersion liquid containing a colorant, a binder resin particle dispersion liquid, and a release agent particle dispersion liquid, and mixing these particle dispersion liquids. The order of mixing these particle dispersion liquids is not limited. Hereinafter, the dispersion liquid formed by mixing a plurality of particle dispersion liquids is referred to as a "mixed dispersion liquid".

[0188] The mass ratio of the particles contained in the mixed dispersion is preferably in the following range, for example.

[0189] The mass ratio of the binder resin particles to the colorant-containing polyester resin particles is, for example, preferably binder resin particles:colorant-containing polyester resin particles=100:1 to 100:100, more preferably 100:2 to 100:60, and even more preferably 100:5 to 100:40.

[0190] The mass ratio of the binder resin particles to the release agent particles is, for example, preferably binder resin particles:release agent particles=100:1 to 100:40, more preferably 100:2 to 100:30, and even more preferably 100:5 to 100:20.

[0191] After mixing the plurality of particle dispersions, the pH of the mixed dispersion is preferably adjusted to, for example, 3 to 4. Examples of methods for adjusting the pH of the mixed dispersion include adding an acidic aqueous solution such as nitric acid, hydrochloric acid, or sulfuric acid.

[0192] The aggregation process includes, for example, the following steps:

[0193] adding a coagulant to the mixed dispersion while stirring the mixed dispersion; and

[0194] After the coagulant is added to the mixed dispersion, the mixed dispersion is heated while stirring the mixed dispersion to increase the temperature of the mixed dispersion.

[0195] Examples of the coagulant include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. The coagulant may be used alone or in combination of two or more.

[0196] Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide; and the like.

[0197] The coagulant is preferably a divalent or higher metal salt compound, more preferably a trivalent metal salt compound, and still more preferably a trivalent inorganic aluminum salt compound. Examples of the trivalent inorganic aluminum salt compound include aluminum chloride, aluminum sulfate, polyaluminum chloride, and polyaluminum hydroxide.

[0198] The amount of the coagulant added is not limited. When a trivalent metal salt compound is used as a coagulant, the amount of the trivalent metal salt compound added is, for example, preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass or less, and further preferably 0.1 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0199] The temperature reached when the mixed dispersion is heated is preferably a temperature based on the glass transition temperature (Tg) of the binder resin particles, for example, not less than (Tg-30°C) and not more than (Tg°C) of the binder resin particles.

[0200] When the mixed dispersion contains a plurality of types of binder resin particles having different Tgs, the lowest temperature among the respective Tgs is defined as the Tg in the aggregation step.

[0201] [Second Aggregation Step]

[0202] The second aggregation step is a step provided for the purpose of producing a toner having a core / shell structure and is a step provided after the first aggregation step. The second aggregation step is a step for forming a shell.

[0203] The second aggregation step is a step of mixing a dispersion containing aggregated particles and a dispersion containing resin particles that serve as shells, and aggregating the resin particles that serve as shells on the surfaces of the aggregated particles to form second aggregated particles.

[0204] The dispersion containing the resin particles that serve as the shell is preferably at least one selected from the dispersions of binder resin particles that serve to form the core, more preferably a dispersion of polyester resin particles, and still more preferably an amorphous polyester resin particle dispersion.

[0205] The second coagulation step includes, for example, the following steps:

[0206] adding a dispersion containing resin particles that serve as shells to the dispersion containing the aggregated particles while stirring the dispersion containing the aggregated particles; and

[0207] The dispersion containing the aggregated particles to which the dispersion containing the resin particles serving as the shells has been added is heated while being stirred.

[0208] The temperature reached when the dispersion containing aggregated particles is heated is preferably a temperature based on the glass transition temperature (Tg) of the resin particles forming the shell, for example, (Tg-30°C) or higher and (Tg-10°C) or lower.

[0209] After the aggregated particles or second aggregated particles grow to a predetermined size and before the heating in the combining step, a chelating agent for the aggregating agent used in the aggregating step may be added to the dispersion containing the aggregated particles or second aggregated particles in order to stop the growth of the aggregated particles or second aggregated particles.

[0210] Examples of the chelating agent include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA); and the like.

[0211] The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of the binder resin particles.

[0212] After the aggregated particles or second aggregated particles grow to a predetermined size, the pH of the dispersion containing the aggregated particles or second aggregated particles may be increased for the purpose of stopping the growth of the aggregated particles or second aggregated particles before heating in the combining step.

[0213] Examples of a method for increasing the pH of the dispersion containing aggregated particles or second aggregated particles include adding at least one selected from the group consisting of an aqueous solution of an alkali metal hydroxide and an aqueous solution of an alkaline earth metal hydroxide.

[0214] The ultimate pH of the dispersion containing the aggregated particles or the second aggregated particles is preferably, for example, 8 or more and 10 or less.

[0215] [Combination process]

[0216] The agglomeration step is a step of heating the dispersion liquid containing the aggregated particles to fuse the aggregated particles into a body to form toner particles.

[0217] When the second aggregation step is provided before the combining step, the combining step is a step of heating the dispersion containing the second aggregated particles to fuse the second aggregated particles to form toner particles. By going through the second aggregation step and the combining step, toner particles with a core / shell structure can be produced.

[0218] The aspects described below are common to the aggregated particles and the second aggregated particles.

[0219] The reaching temperature of the dispersion containing the aggregated particles is preferably, for example, not less than the glass transition temperature (Tg) of the binder resin, and specifically, preferably a temperature 10° C. to 30° C. higher than the Tg of the binder resin.

[0220] When the aggregated particles contain a plurality of binder resins having different Tgs, the highest temperature among the respective Tgs is defined as the glass transition temperature in the combining step.

[0221] After the combination process is completed, the toner particles in the dispersion are subjected to a known washing process, a solid-liquid separation process, and a drying process to obtain dry toner particles. From the perspective of chargeability, the washing process is preferably performed by, for example, fully performing replacement washing with deionized water. From the perspective of productivity, the solid-liquid separation process is preferably performed by, for example, suction filtration, pressure filtration, etc. From the perspective of productivity, the drying process is preferably performed by, for example, freeze drying, airflow drying, fluidized bed drying, vibration-type fluidized bed drying, etc.

[0222] [Process of adding external additives]

[0223] The method for producing a toner according to the present embodiment preferably includes, for example, a step of adding an external additive to toner particles.

[0224] The external additive is added to the toner particles by mixing the toner particles in a dry state with the external additive. The mixing is performed, for example, by a V mixer, a Henschel mixer, a Lödige mixer, etc. Furthermore, coarse particles of the toner may be removed by using a vibration sieving machine, a wind sieving machine, etc. as needed.

[0225] Examples of external additives include inorganic particles. Examples of inorganic particles include SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2) n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0226] For the surface of the inorganic particles as an external additive, for example, a hydrophobic treatment is preferably implemented. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and for example, a silane coupling agent, silicone oil, a titanate coupling agent, an aluminum coupling agent, etc. can be cited. They can be used alone or in combination of two or more.

[0227] Usually, the amount of the hydrophobizing agent is, for example, 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic particles.

[0228] Examples of the external additives include resin particles (polystyrene, polymethyl methacrylate, melamine resin, and other resin particles), cleaning aids (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based high molecular weight bodies), and the like.

[0229] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2% by mass or less, relative to the mass of the toner particles.

[0230] <Toner for electrostatic latent image development>

[0231] The toner produced by the production method according to the present embodiment is preferably an externally added toner obtained by adding an external additive to toner particles, for example. The form of the external additive is as described above.

[0232] The toner particles contain at least a polyester resin and a basic colorant. The toner particles may contain a binder resin other than the polyester resin. The toner particles may contain a release agent.

[0233] The total content of the polyester resin is, for example, preferably 40 mass % to 95 mass % inclusive, more preferably 50 mass % to 90 mass % inclusive, and further preferably 60 mass % to 85 mass % inclusive, based on the entire toner.

[0234] When the toner particles contain a crystalline polyester resin, the content of the crystalline polyester resin is, for example, preferably 3% by mass or more and 30% by mass or less, and more preferably 8% by mass or more and 20% by mass or less, based on the total binder resin.

[0235] The content of the releasing agent is, for example, preferably 1 mass % or more and 20 mass % or less, and more preferably 5 mass % or more and 15 mass % or less, based on the entire toner.

[0236] The content of the basic colorant is, for example, preferably 1 mass % or more and 30 mass % or less, and more preferably 3 mass % or more and 15 mass % or less, based on the entire toner.

[0237] The volume average particle size of the toner is, for example, preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less. The method for measuring the volume average particle size of the toner is as follows.

[0238] The particle size distribution of the toner is measured using Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) and ISOTON-II (manufactured by Beckman Coulter, Inc.) for the electrolyte. During the measurement, as a dispersant, add 0.5 mg or more and 50 mg or less of the measurement sample to 2 ml of a 5% aqueous solution of a surfactant (e.g., preferably sodium alkylbenzene sulfonate). Add it to an electrolyte of 100 ml or more and 150 ml or less. The electrolyte in which the sample is suspended is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm or more and 60 μm or less is measured using a Coulter Multisizer II with a hole of 100 μm in diameter. The number of particles measured is 50,000. The particle size distribution is plotted from the smaller diameter side, and the particle size when accumulated to 50% is set as the volume average particle size D50v.

[0239] The average circularity of the toner is, for example, preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0240] The average circularity of the toner is (the circumference of a circle having the same area as the particle projection image) / (the circumference of the particle projection image) and is determined by measuring 3,500 particles using a flow particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).

[0241] <Developer>

[0242] The toner produced by the production method according to the present embodiment may be used as a single-component developer, or may be mixed with a carrier and used as a two-component developer.

[0243] The carrier is not particularly limited, and known carriers may be used. Examples of the carrier include a coated carrier in which the surface of a core material composed of magnetic powder is coated with a resin; a magnetic powder dispersed carrier in which magnetic powder is dispersed in a matrix resin; a resin impregnated carrier in which porous magnetic powder is impregnated with a resin; and the like.

[0244] The magnetic powder dispersed carrier or the resin impregnated carrier may be a carrier having constituent particles of the carrier as a core material and the surface of the core material coated with a resin.

[0245] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; magnetic oxides such as ferrite and magnetite; and the like.

[0246] As the coating resin and the base resin, for example, polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, acrylate copolymer, styrene-acrylate copolymer, resin with cycloalkyl group, acrylate copolymer with cycloalkyl group, straight-chain silicone resin or its modified product containing organic siloxane bond, fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, etc. are mentioned. For example, acrylate copolymer, styrene-acrylate copolymer, resin with cycloalkyl group, acrylate copolymer with cycloalkyl group are preferred. The coating resin and the base resin may contain other additives such as conductive particles. As conductive particles, metals such as gold, silver, copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, potassium titanate and other particles can be mentioned.

[0247] In order to coat the surface of the core material with resin, a coating layer formed by dissolving the coating resin and various additives (used as required) in a suitable solvent can be enumerated to coat with a solution, etc. As the solvent, there is no particular limitation, as long as the type of the resin used and coating suitability are considered to select.

[0248] Specific resin coating methods include an immersion method in which the core material is immersed in a coating layer forming solution; a spraying method in which the coating layer forming solution is sprayed on the surface of the core material; a fluidized bed method in which the coating layer forming solution is sprayed while the core material is suspended by flowing air; a kneading coating method in which the core material of the carrier and the coating layer forming solution are mixed in a kneading coater and then the solvent is removed; and the like.

[0249] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is, for example, preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0250] Example

[0251] Hereinafter, embodiments of the present invention will be described in detail based on examples, but embodiments of the present invention are not limited to these examples.

[0252] In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0253] In the following description, unless otherwise specified, synthesis, production, treatment, measurement, etc. were performed at room temperature (25° C.±3° C.).

[0254] <Preparation of amorphous polyester resin (A)>

[0255] The following materials were prepared.

[0256] Terephthalic acid: 30 mol parts

[0257] Fumaric acid: 70 mol parts

[0258] Bisphenol A ethylene oxide adduct: 5 mol parts

[0259] Bisphenol A propylene oxide adduct: 95 mol parts

[0260] The above materials were placed in a flask equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor and a distillation tower, and the temperature of the reaction liquid was raised to 220°C over 1 hour, and 1 part of tetraethoxytitanium was added to 100 parts of the above materials. The temperature of the reaction liquid was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while the temperature of the reaction liquid was maintained at 230°C. Then, the temperature of the reactant was cooled to room temperature. In this way, an amorphous polyester resin (A) with an acid value of 12.0 mgKOH / g, a weight average molecular weight of 18,000, and a glass transition temperature of 60°C was obtained.

[0261] <Preparation of Colorant-Containing Polyester Resin Particle Dispersion (P1)>

[0262] The following materials were prepared.

[0263] Fluorescent colorant (trade name: Basic Violet 11:1, Taoka Chemical Co., Ltd.): 2 parts

[0264] Amorphous polyester resin (A): 200 parts

[0265] Alkaline compound: 25% sodium hydroxide aqueous solution: 0.4 parts

[0266] Surfactant: 48.5% sodium dodecyl diphenyl ether disulfonate aqueous solution (trade name: ELEMINOL MON-7, SANYO CHEMICAL INDUSTRIES, LTD.): 4.1 parts

[0267] Deionized water (1): 150 parts deionized water at 95°C

[0268] Deionized water (2): 150 parts of deionized water at 95°C

[0269] Deionized water (3): 150 parts of deionized water at 95°C

[0270] A twin-screw kneading extruder (model: TEM26SS, Toshiba Machine Co., Ltd.) was prepared. The barrel of the twin-screw kneading extruder used in this example was formed by connecting a plurality of barrel blocks, and the overall L / D was 50.

[0271] - Melting process -

[0272] The barrel temperature of the twin-screw kneading extruder was set to 95°C and the screw speed was set to 400 rpm. The fluorescent colorant, the amorphous polyester resin (A) and the 25% sodium hydroxide aqueous solution were added to the raw material inlet of the twin-screw kneading extruder, and the operation of the twin-screw kneading extruder was started. The surfactant was added from the barrel of the fourth block, and kneading and stirring were performed to melt the resin to prepare a mixture.

[0273] -Emulsification process-

[0274] While operating the twin-screw kneading extruder so that the average supply rate of the mixture becomes 12 kg / h, deionized water (1) is added from the barrel of the fifth block, deionized water (2) is added from the barrel of the seventh block, and deionized water (3) is added from the barrel of the ninth block to emulsify the mixture, thereby obtaining a polyester resin particle dispersion (P1) containing a colorant. The solid content concentration of the polyester resin particle dispersion (P1) containing a colorant is 31%.

[0275] The particle size distribution of the particles in the colorant-containing polyester resin particle dispersion (P1) was measured using a laser diffraction particle size distribution analyzer (model: LS13-320, Beckman Coulter, Inc.) The volume average particle size of the particles in the colorant-containing polyester resin particle dispersion (P1) was 200 nm.

[0276] <Preparation of Colorant-Containing Polyester Resin Particle Dispersions (P2), (P3), (P9) to (P14)>

[0277] The polyester resin particle dispersion containing a colorant was prepared in the same manner as the preparation of the polyester resin particle dispersion containing a colorant (P1), except that the specifications and operating conditions of the twin-screw kneading extruder were changed as shown in Table 1. The volume average particle size of the particles in the polyester resin particle dispersion containing a colorant was 200 nm.

[0278] <Preparation of Polyester Resin Particle Dispersion (P4) Containing Colorant>

[0279] The following materials were prepared.

[0280] Organic solvent (1): ethyl acetate: 40 parts

[0281] Organic solvent (2): Isopropyl alcohol: 25 parts

[0282] Fluorescent colorant (trade name: Basic Violet 11:1, Taoka Chemical Co., Ltd.): 2 parts

[0283] Amorphous polyester resin (A): 100 parts

[0284] Alkaline compound: 10% ammonia water: 11 parts

[0285] Deionized water (4): 200 parts of deionized water at 40°C

[0286] -Dissolution process-

[0287] An organic solvent (1) and an organic solvent (2) are placed in a stirring tank equipped with a stirrer, a capacitor, a heating device, and a thermometer to prepare a mixed solvent. A fluorescent colorant and amorphous polyester resin (A) are added while stirring the stirring tank while maintaining the temperature in the range of 35°C to 55°C, and stirred for 60 minutes to dissolve the fluorescent colorant and the resin in the organic solvent.

[0288] -Emulsification process-

[0289] While maintaining the temperature in the stirring tank and continuing stirring, 10% ammonia water is added, and then deionized water (4) is added dropwise over 90 minutes to emulsify the contents. The heating of the stirring tank is stopped, and the temperature of the emulsion is lowered to room temperature. Then, while maintaining the temperature in the stirring tank within the range of 40°C to 55°C, the pressure in the stirring tank is reduced to 10 kPa to remove the organic solvent from the emulsion. The emulsion is passed through a sieve, and 2.1 parts of a 48.5% aqueous solution of sodium dodecyl diphenyl oxide disulfonate (trade name: ELEMINOL MON-7, SANYO CHEMICAL INDUSTRIES, LTD.) and 30 parts of deionized water are added to obtain a polyester resin particle dispersion (P4) containing a colorant.

[0290] The solid content concentration of the polyester resin particle dispersion (P4) containing a colorant was 31%. The volume average particle size of the particles in the polyester resin particle dispersion (P4) containing a colorant was 200 nm.

[0291] <Preparation of Colorant-Containing Polyester Resin Particle Dispersions (P5) to (P8)>

[0292] The polyester resin particle dispersion containing a colorant was prepared in the same manner as the preparation of the polyester resin particle dispersion containing a colorant (P4), except that the temperature of the emulsification step was changed as shown in Table 1. The volume average particle size of the particles in the polyester resin particle dispersion containing a colorant was 200 nm.

[0293] <Preparation of amorphous polyester resin particle dispersion (1)>

[0294] The following materials were prepared.

[0295] Terephthalic acid: 30 mol parts

[0296] Fumaric acid: 70 mol parts

[0297] Bisphenol A ethylene oxide adduct: 5 mol parts

[0298] Bisphenol A propylene oxide adduct: 95 mol parts

[0299] The above materials were placed in a flask equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor and a distillation tower, and the temperature of the reaction liquid was raised to 220°C over 1 hour, and 1 part of tetraethoxytitanium was added to 100 parts of the above materials. The temperature of the reaction liquid was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while the temperature of the reaction liquid was maintained at 230°C. Then, the temperature of the reactant was cooled to room temperature. In this way, an amorphous polyester resin with an acid value of 12.0 mgKOH / g, a weight average molecular weight of 18,000, and a glass transition temperature of 60°C was obtained.

[0300] A mixed solvent was prepared by adding 40 parts of ethyl acetate and 25 parts of 2-butanol to a container equipped with a temperature regulating member and a nitrogen replacement member. 100 parts of amorphous polyester resin was gradually added to the mixed solvent to dissolve it, and a 10% aqueous ammonia solution (equivalent to 3 times the amount in molar ratio relative to the acid value of the resin) was added and stirred for 30 minutes. Next, the inside of the container was replaced with dry nitrogen, the temperature of the reaction liquid was maintained at 40°C, and while stirring the reaction liquid, 400 parts of deionized water was added dropwise at a rate of 2 parts / minute to emulsify it. After the addition of deionized water was completed, the temperature of the emulsion was cooled to room temperature (20°C to 25°C), and while stirring the emulsion, dry nitrogen was bubbled for 48 hours to reduce the total amount of ethyl acetate and 2-butanol to less than 1000 ppm. Deionized water was added to the emulsion to adjust the solid content concentration to 20%. In this way, an amorphous polyester resin particle dispersion (1) was obtained. The volume average particle size of the particles in the amorphous polyester resin particle dispersion (1) was 160 nm.

[0301] <Preparation of Release Agent Particle Dispersion (1)>

[0302] The following materials were prepared.

[0303] Paraffin (HNP-9, NIPPON SEIRO CO., LTD.): 100 parts

[0304] Deionized water: 350 parts

[0305] Anionic surfactant (trade name: NEOGEN RK, manufactured by DKS Co. Ltd., 20% aqueous solution): 1 part

[0306] The above materials were mixed and heated to 100°C, dispersed using a homogenizer (ULTRA TURRAX T50, IKA), and then dispersed using a pressure-dispensing homogenizer (Manton-Gaulin high-pressure homogenizer, Gaulin). When the volume average particle size reached 200 nm, the particles were recovered to obtain a release agent particle dispersion (1) having a solid content concentration of 20%.

[0307] <Example 1>

[0308] [Manufacturing of Toner Particles]

[0309] The following materials were prepared.

[0310] Deionized water: 7 parts

[0311] Amorphous polyester resin particle dispersion (1): 50 parts

[0312] Polyester resin particle dispersion containing colorant (P1): 13 parts

[0313] Release agent particle dispersion (1): 10 parts

[0314] Anionic surfactant (trade name: NEOGEN RK, manufactured by DKS Co. Ltd., 20% aqueous solution): 1 part -First aggregation step-

[0315] The above materials were placed in a round stainless steel flask, 0.1N nitric acid was added and the pH was adjusted to 3.5, and 30 parts of a nitric acid aqueous solution with a polyaluminum chloride concentration of 10% was added. The liquid temperature was adjusted to 30°C using an oil bath, and a homogenizer (trade name: ULTRA TURRAX T50, IKA) was used for dispersion treatment. Then, the liquid temperature was raised to 45°C and maintained for 30 minutes to form the first aggregated particles.

[0316] -Second Coagulation Step-

[0317] While the liquid temperature of the dispersion containing the first aggregated particles was maintained at 45° C., 20 parts of the amorphous polyester resin particle dispersion (1) was added and maintained for 60 minutes to form second aggregated particles.

[0318] -Combination process-

[0319] A 0.1 N sodium hydroxide aqueous solution was added to the dispersion containing the second aggregated particles and the pH was adjusted to 8.5. The liquid temperature was raised to 84°C and maintained for 150 minutes. Then, the dispersion was cooled to 20°C at a rate of 20°C / min, and the solid content was filtered out, washed with deionized water, and dried. The dried product was sieved to obtain toner particles (1). The volume average particle size of the toner particles (1) was 6.0 μm.

[0320] [Manufacturing of external toner]

[0321] 1.5 parts of hydrophobic silica particles (product code: RY50, NIPPONAEROSIL CO., LTD.) and 1.0 part of hydrophobic titanium oxide (product code: T805, NIPPON AEROSIL CO., LTD.) were added to 100 parts of the toner particles (1), and mixed at 10000 rpm for 30 seconds using a sample mill. Then, the mixture was sieved with a vibration sieve having an aperture of 45 μm to obtain an external toner.

[0322] [Manufacturing of developer]

[0323] 8 parts of the external toner and 92 parts of the following carrier (1) were placed in a V mixer and stirred for 20 minutes, and then sieved with a sieve having an aperture of 212 μm to obtain a developer.

[0324] -Manufacturing of carrier (1)-

[0325] 14 parts of toluene, 5 parts of cyclohexyl methacrylate-monoethylaminoethyl methacrylate copolymer (mass ratio 95:5, weight average molecular weight 60000) and 0.2 parts of carbon black (product code: VXC-72, Cabot Corporation) were placed in a sand mill and dispersed to prepare a dispersion. The dispersion and 100 parts of ferrite particles (average particle size 35 μm) were placed in a vacuum degassing kneader and dried under reduced pressure while stirring to obtain a carrier (1).

[0326] <Example 2 to Example 12, Comparative Example 1 to Comparative Example 2>

[0327] The same procedure as in Example 1 was carried out except that the type of the polyester resin particle dispersion containing the colorant was changed as shown in Table 1, and toner particles, an external toner, and a developer were prepared.

[0328] <Performance Evaluation>

[0329] [Uneven Image Density]

[0330] The following operations and image formation were performed in an environment with a temperature of 23°C and a relative humidity of 70%. The lower the dispersibility of the colorant inside the toner particles, the more there is a concern about charge leakage caused by the low dispersibility of the colorant, and the image density unevenness caused by charge leakage is more likely to occur. Images were formed under slightly higher humidity conditions.

[0331] As an image forming apparatus for forming an evaluation image, ApeosPortIV C4470 (FUJIFILM Business Innovation Corp.) was prepared. A developer was placed in a developing device, and a replenishment toner (the same toner as that contained in the developer) was placed in a toner cartridge.

[0332] On A4 size OS coated paper (basis weight 127g / m 2 , FUJIFILM Business Innovation Japan Corp.) were used to output 100 images with an image density of 30%. The image density was measured at any 10 locations on the 100th image using a densitometer (X-Rite938, X-RITE). The difference between the maximum and minimum values ​​of the image density at the 10 locations (image density difference) was calculated, and the image density difference was classified as follows. The results are shown in Table 1.

[0333] A: Image density difference is 0.20 or less

[0334] B: Image density difference is more than 0.20 and less than 0.25

[0335] C: Image density difference is more than 0.25 and less than 0.30

[0336] D: Image density difference exceeds 0.30

[0337] [Heat preservation properties]

[0338] 2 g of the external toner was stored in an environment of a temperature of 55° C. and a relative humidity of 50% for 10 hours. The external toner after storage was observed with the naked eye and classified as follows. The results are shown in Table 1.

[0339] A: No agglutinate was observed.

[0340] B: A small amount of agglutinate is present.

[0341] C: Almost entirely agglutinated.

[0342]

[0343] The method for producing the electrostatic latent image developing toner of the present invention includes the following aspects. (1)

[0345] A method for producing a toner for electrostatic latent image development, comprising the steps of aggregating and combining material particles including polyester resin particles containing a colorant in a dispersion medium to obtain toner particles, the method for producing a toner for electrostatic latent image development comprising a step of producing the polyester resin particles containing a colorant,

[0346] The process for producing the colorant-containing polyester resin particles comprises the steps of: mixing a basic colorant and a polyester resin while applying heat to obtain a mixture; and emulsifying the mixture.

[0347] In the process of producing the colorant-containing polyester resin particles, the time-weighted average T°C of the temperature of the polyester resin and the time R seconds during which the temperature of the polyester resin is within the range of 35°C to 100°C satisfy the relationship of 200≤(T×lnR)≤550. (2)

[0349] The method for producing a toner for developing an electrostatic latent image according to (1), wherein:

[0350] In the entire process of producing the colorant-containing polyester resin particles, the temperature of the polyester resin is within a range of 35° C. to 100° C. (3)

[0352] The method for producing a toner for developing an electrostatic latent image according to (1) or (2), wherein:

[0353] In the production process of the colorant-containing polyester resin particles, no organic solvent is used. (4)

[0355] The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (3), wherein:

[0356] The basic colorant includes a basic dye. (5)

[0358] The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (4), wherein:

[0359] The polyester resin includes an amorphous polyester resin. (6)

[0361] The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (5), wherein:

[0362] The mass ratio of the basic colorant to the polyester resin contained in the colorant-containing polyester resin particles is basic colorant:polyester resin=0.1:99.9 to 20:80. (7)

[0364] The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (6), wherein:

[0365] The volume average particle diameter of the colorant-containing polyester resin particles is 50 nm or more and 500 nm or less.

[0366] According to (1), (2), (3), (4), (5), (6) or (7), there is provided a method for producing a toner for electrostatic latent image development which suppresses the occurrence of image density unevenness and has excellent thermal storage properties compared to the case where the value of (T×lnR) is less than 200 or exceeds 550.

[0367] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A method for producing a toner for electrostatic latent image development, comprising the steps of: aggregating and combining material particles including polyester resin particles containing a colorant in a dispersion medium to obtain toner particles, the method for producing a toner for electrostatic latent image development comprising a step of producing the polyester resin particles containing a colorant, The process for producing the colorant-containing polyester resin particles comprises the steps of: mixing a basic colorant and a polyester resin while applying heat to obtain a mixture; and emulsifying the mixture. In the process of producing the colorant-containing polyester resin particles, the time-weighted average T°C of the temperature of the polyester resin and the time R seconds during which the temperature of the polyester resin is within the range of 35°C to 100°C satisfy the relationship of 200≤(T×lnR)≤550.

2. The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein: In the entire process of producing the colorant-containing polyester resin particles, the temperature of the polyester resin is within a range of 35° C. to 100° C.

3. The method for producing a toner for developing an electrostatic latent image according to claim 1 or 2, wherein: In the production process of the colorant-containing polyester resin particles, no organic solvent is used.

4. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 3, wherein: The basic colorant includes a basic dye.

5. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 4, wherein: The polyester resin includes an amorphous polyester resin.

6. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 5, wherein: The mass ratio of the basic colorant to the polyester resin contained in the colorant-containing polyester resin particles is basic colorant:polyester resin=0.1:99.9 to 20:

80.

7. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 6, wherein: The volume average particle diameter of the colorant-containing polyester resin particles is 50 nm or more and 500 nm or less.

Images