JP2009031677A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner excellent in a storage property and fixing characteristic obtained by a method having a process of granulating a raw material in an aqueous medium, and a production method therefor. <P>SOLUTION: Provided are the electrophotographic toner obtained by a method comprising a process of granulating a raw material including a polyester in an aqueous medium, wherein the polyester is obtained by condensation polymerization of an alcohol component containing 20-100 mol% of an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms bonded with a hydroxyl group and a carboxylic acid component, and a production method therefor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Conventionally, styrene acrylic resins and polyesters are known as toner binder resins, but toners containing polyester are widely used because of their excellent durability and fixability. As such a toner, particularly from the viewpoint of fixability, a polyester containing an alkyl succinic acid and / or alkenyl succinic acid having 10 or more carbon atoms as a carboxylic acid component, and a toner by a melt kneading and pulverizing method using this as a binder resin Is disclosed (see Patent Documents 1 and 2).

On the other hand, in recent years, from the pursuit of high image quality, development of a small particle size toner excellent in fixing property has been desired. However, when a small particle size toner containing a polyester-based binder resin is produced by a melt-kneading pulverization method, pulverization control is difficult. Thus, for example, Patent Document 3 discloses a method for producing a toner by an emulsion aggregation method, which is a wet production method, using a binder resin having a carboxyl group.
JP-A-57-109825 JP 2000-35695 A JP 2004-198598 A

  However, when a toner containing polyester as a binder resin is produced by a wet process, the ester bond of the polyester is hydrolyzed in the solution, resulting in a decrease in the molecular weight and glass transition point of the resulting toner. Fixing characteristics such as offset and low-temperature fixability may deteriorate.

  An object of the present invention is to provide an electrophotographic toner obtained by a method having a step of forming raw materials into particles in an aqueous medium, which is excellent in storage stability and fixing characteristics, and a method for producing the same. It is in.

The present invention
[1] A toner obtained by a method including a step of granulating a raw material containing polyester in an aqueous medium, wherein the polyester is an aliphatic polyhydric alcohol having two or more secondary carbon atoms to which hydroxyl groups are bonded ( Toner for electrophotography, which is a polyester obtained by condensation polymerization of an alcohol component containing 20 to 100 mol% of alcohol A) and a carboxylic acid component, and [2] A raw material containing polyester is granulated in an aqueous medium A method for producing an electrophotographic toner comprising the step of: wherein the polyester contains 20 to 100 mol% of an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms to which a hydroxyl group is bonded. The present invention relates to a method for producing an electrophotographic toner, which is a polyester obtained by condensation polymerization of a component and a carboxylic acid component.

  The toner for electrophotography of the present invention is a toner obtained by a method having a step of forming a raw material into an aqueous medium and exhibits excellent effects in both storage stability and fixing characteristics.

  In the electrophotographic toner of the present invention, the polyester contained as a binder resin has an alcohol component containing a specific amount of an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms bonded to a hydroxyl group; It has a great feature in that it is a polyester obtained by polycondensation with a carboxylic acid component, and has excellent storability and fixing properties. This is because the alkyl group bonded to the secondary carbon to which the hydroxyl group contained in the polyester binds restricts the mobility of the molecule and has a bulky functional group adjacent to the α-position, thereby Since the hydrolysis of polyester ester bonds is suppressed when forming particles in an aqueous medium, polyester having a broad molecular weight distribution can be contained in the toner without causing deterioration of the polyester. It is presumed that a resin having a higher glass transition point can be obtained without impairing the fixing characteristics.

  Examples of the aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms bonded with a hydroxyl group include 2,3-butanediol, 2,3-pentanediol, 2,4-pentanediol, 2,3 -Hexanediol, 3,4-hexanediol, 2,4-hexanediol, 2,5-hexanediol and the like.

  The number of carbon atoms of the aliphatic polyhydric alcohol is preferably 4 to 8, and more preferably 4 to 5, from the viewpoint of increasing the ester value and improving the fixing property. In addition, from the viewpoint of making the main chain skeleton rigid and increasing the density of the functional group serving as a protecting group for hydrolysis, one set of secondary carbon atoms in which secondary carbon atoms to which hydroxyl groups are bonded are adjacent to each other. The aliphatic polyhydric alcohol having the above is more preferable. From these viewpoints, secondary carbon atoms bonded with hydroxyl groups such as 2,3-butanediol, 2,3-pentanediol, 2,3-hexanediol, and 3,4-hexanediol are adjacent to each other. An aliphatic polyhydric alcohol having 4 to 8 carbon atoms and having at least one set of carbon atoms is more preferable.

  Content of alcohol A is 20-100 mol% in an alcohol component, Preferably it is 20-90 mol%, More preferably, it is 20-80 mol%, More preferably, it is 25-80 mol%.

  In the present invention, it is preferable that the alcohol component further contains an aliphatic diol having 2 to 6 carbon atoms (alcohol B) other than alcohol A, from the viewpoint of ease of raising the ester value. As alcohol B, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, neopentyl glycol and the like can be mentioned, and among these, ethylene glycol, 1,2-propanediol and 1,3-propanediol are preferable from the viewpoint of the rigidness of the skeleton.

  The content of the alcohol B is preferably 0.5 to 80 mol%, more preferably 10 to 70% mol%, still more preferably 20 to 60 mol% in the alcohol component.

  Examples of alcohol components other than alcohol A and alcohol B include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, I):

(In the formula, RO is an alkyleneoxy group, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of added moles of alkylene oxide, and the sum of x and y is 1 to 16, preferably 1.5-5)
An aromatic diol such as an alkylene oxide adduct of bisphenol represented by the formula: a trihydric or higher polyhydric alcohol such as glycerin.

  Examples of carboxylic acid components include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, etc. An aliphatic dicarboxylic acid such as phthalic acid, isophthalic acid and terephthalic acid; an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid; a trivalent or higher polyvalent carboxylic acid such as trimellitic acid and pyrrolemetic acid; and These acid anhydrides, alkyl (C1-3) esters; rosins; rosins modified with fumaric acid, maleic acid, acrylic acid, and the like. Such acids, anhydrides of these acids, and alkyl esters of these acids are collectively referred to herein as carboxylic acid compounds.

  In the present invention, the carboxylic acid component desirably contains a trivalent or higher polyvalent carboxylic acid compound, preferably a trimellitic acid compound, more preferably trimellitic anhydride, from the viewpoint of easily increasing the molecular weight. The content of the trivalent or higher polyvalent carboxylic acid compound is preferably from 0.1 to 30 mol%, more preferably from 1 to 20 mol%, still more preferably from 3 to 20 mol% in the carboxylic acid component.

  The alcohol component may contain a monovalent alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoints of molecular weight adjustment and offset resistance improvement.

  The polycondensation of the alcohol component and the carboxylic acid component is preferably performed at a temperature of 180 to 250 ° C. in an inert gas atmosphere in the presence of an esterification catalyst such as a tin compound or a titanium compound.

  As the tin compound, for example, dibutyltin oxide is known, but in the present invention, a tin (II) compound having no Sn—C bond is preferable from the viewpoint of good dispersibility in the polyester. .

  Examples of the tin (II) compound having no Sn—C bond include a tin (II) compound having a Sn—O bond, a tin (II) compound having a Sn—X (X represents a halogen atom) bond, and the like. Preferably, a tin (II) compound having a Sn—O bond is more preferable.

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

Specific examples of titanium compounds include titanium diisopropylate bistriethanolamate [Ti (C ₆ H ₁₄ O ₃ N) ₂ (C ₃ H ₇ O) ₂ ], titanium diisopropylate bisdiethanolamate [Ti (C ₄ H ₁₀ O ₂ N) ₂ (C ₃ H ₇ O) ₂ ], titanium dipentylate bistriethanolamate [Ti (C ₆ H ₁₄ O ₃ N) ₂ (C ₅ H ₁₁ O) ₂ ], titanium diety rate bis triethanolaminate _{[Ti (C 6 H 14 O 3} N) 2 (C 2 H 5 O) 2 ], titanium dihydroxy octylate bis triethanolaminate _{[Ti (C 6 H 14 O 3} N) 2 (OHC 8 H ₁₆ O) ₂ ], titanium distearate bistriethanolamate [Ti (C ₆ H ₁₄ O ₃ N) ₂ (C ₁₈ H ₃₇ O) ₂ ], titanium triisopropylate triethanolamate [Ti (C ₆ H ₁₄ O ₃ N) (C ₃ H ₇ O) ₃ ], titanium monopropylate tris (triethanolaminate) [Ti (C ₆ H ₁₄ O ₃ N) ₃ (C ₃ H ₇ O)] and the like, among these, titanium diisopropylate bistri Ethanolaminate, titanium diisopropylate bisdiethanolamate and titanium dipentylate bistriethanolamate are preferred, and these are also available as commercial products of Matsumoto Trading Co., Ltd., for example.

Specific examples of other preferable titanium compounds include tetra-n-butyl titanate [Ti (C ₄ H ₉ O) ₄ ], tetrapropyl titanate [Ti (C ₃ H ₇ O) ₄ ], tetrastearyl titanate [Ti ( C ₁₈ H ₃₇ O) ₄ ], tetramyristyl titanate [Ti (C ₁₄ H ₂₉ O) ₄ ], tetraoctyl titanate [Ti (C ₈ H ₁₇ O) ₄ ], dioctyl dihydroxyoctyl titanate [Ti (C ₈ H ₁₇ O) ₂ (OHC ₈ H ₁₆ O) ₂ ], dimyristyl dioctyl titanate [Ti (C ₁₄ H ₂₉ O) ₂ (C ₈ H ₁₇ O) ₂ ] and the like. Among these, tetrastearyl titanate, tetra Myristyl titanate, tetraoctyl titanate and dioctyl dihydroxy octyl titanate are preferred. These can be obtained, for example, by reacting a titanium halide with a corresponding alcohol, or can be obtained as a commercial product such as Nisso.

  The abundance of the esterification catalyst is preferably 0.05 to 1 part by weight, more preferably 0.2 to 0.7 part by weight, based on 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  In addition, polyester modified | denatured to such an extent that the characteristic is not impaired substantially may be sufficient. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Polyester.

  The softening point of the polyester is preferably 90 to 160 ° C, more preferably 95 to 155 ° C, and still more preferably 100 to 150 ° C, from the viewpoints of fixability, storage stability and durability. The glass transition point is preferably 45 to 75 ° C, more preferably 50 to 70 ° C, from the viewpoints of fixability, storage stability, and durability. From the viewpoint of chargeability and environmental stability, the acid value is preferably 1 to 80 mgKOH / g, more preferably 5 to 60 mgKOH / g, further preferably 5 to 50 mgKOH / g, and the hydroxyl value is 1 to 80 mgKOH / g. Preferably, 8 to 60 mgKOH / g is more preferable, 8 to 50 mgKOH / g is more preferable, and 8 to 40 mgKOH / g is more preferable.

  By using the polyester as a binder resin, an electrophotographic toner excellent in both low-temperature fixability and storage stability, which are mutually contradictory performances, can be obtained. In the toner of the present invention, other known binder resins such as polyesters other than those described above, vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, etc. may be used as long as the effects of the present invention are not impaired. Although a resin may be used in combination, the content of the condensation polymerization resin of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 80% by weight or more in the binder resin. It is more preferably 90% by weight or more, and further preferably substantially 100% by weight.

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

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

  The electrophotographic toner of the present invention is not particularly limited as long as it is obtained by a method including a step of forming a raw material containing polyester into an aqueous medium, and for example, (A) in an aqueous medium (B) a method of aggregating and coalescing primary particles after forming primary particles in advance, (B) a method of forming primary particles in advance in an aqueous medium and then fusing the primary particles, and (C) including polyester. Examples thereof include a method of dispersing raw materials in an aqueous medium to form particles. In the present invention, the method (A) is preferred, and the step (1) of producing primary particles containing a binder resin containing polyester in an aqueous medium in the presence of a nonionic surfactant, and the primary particles A method comprising the step (2) of aggregating and coalescing the two is preferable. In addition, as another specific example of the method (A), the organic solvent is removed after introducing the aqueous solution into the mixed solution prepared by dissolving or dispersing the raw material containing the binder resin in the organic solvent. As a specific example of a method for aggregating the resin particles and a method (B) for obtaining a self-dispersing aqueous resin particle dispersion, a radical polymerizable monomer solution in which a binder resin is dissolved is emulsion-polymerized. Specific examples of a method for obtaining resin fine particles and fusing the resin fine particles in an aqueous medium (see Japanese Patent Application Laid-Open No. 2001-42568) and method (C) include resin heat melting made of a raw material containing a binder resin. Examples thereof include a method in which the body is dispersed in an aqueous medium not containing an organic solvent while maintaining the molten state of the binder resin, and then dried (see JP-A-2001-235904).

  By mixing the binder resin containing polyester and the nonionic surfactant, the viscosity of the mixture can be reduced, and the binder resin can be atomized. This is because the ionic surfactant is compatible with the binder resin and the softening point of the resin is apparently lowered. By utilizing this phenomenon, the apparent softening point of the binder resin compatible with the nonionic surfactant can be lowered below the boiling point of water, and the resin alone has a melting point or softening point of 100 ° C. or higher. Even with the binder resin, a dispersion liquid in which the binder resin is dispersed in water can be obtained by dropping water at normal pressure. This method requires at least water and a nonionic surfactant, so it can be applied to resins that are insoluble in organic solvents, and does not require the burden of equipment for recovering organic solvents and maintaining the work environment. There is also an advantage that a resin dispersion can be produced economically because a special device required when using mechanical means is not required.

  In the present invention, the aqueous medium may contain a solvent such as an organic solvent, but water is preferably 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and further preferably 99%. According to the above method, the binder resin can be atomized by using only water without using an organic solvent. In the case of using a solvent, methyl ethyl ketone, tetrahydrofuran, toluene, ethyl acetate, etc. are preferable in consideration of the solubility of the resin.

  Nonionic surfactants include, for example, polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyoxyethylene sorbitan mono Polyoxyethylene sorbitan esters such as laurate, polyoxyethylene sorbitan monostearate, polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, oxyethylene / Oxypropylene block copolymer and the like. In addition, an anionic surfactant or a cationic surfactant may be used in combination with the nonionic surfactant.

  As the nonionic surfactant, it is preferable to select a nonionic surfactant having good compatibility with the resin. In order to obtain a stable binder resin dispersion, the HLB of the nonionic surfactant is preferably 12 to 18, and depending on the type of the binder resin, two or more different HLB nonionic interfaces may be used. More preferably, an activator is used. For example, in the case of a highly hydrophilic resin, at least one nonionic surfactant having an HLB of 12 to 18 may be used. In the case of a highly hydrophobic resin, a low HLB, for example, an HLB of 7 It is preferable to adjust the weighted average of both HLBs to 12-18 by using about ~ 10 and those having high HLB, for example, 14-20 HLB. In this case, it is presumed that mainly those having an HLB of about 7 to 10 can compatibilize the resin, and those having a high HLB can stabilize the dispersion of the resin in water.

  When a colorant is used, the nonionic surfactant is preferably adsorbed on the colorant and dispersed in the binder resin. By adjusting the HLB of the nonionic surfactant to the above range, the nonionic surfactant is easily adsorbed on the colorant surface, and at the same time, the colorant is present as a colloidal dispersion in an aqueous medium. It is preferable because it stably exists in the binder resin.

  The clouding point of the nonionic surfactant is preferably 70 to 105 ° C., more preferably 80 to 105 ° C. when the binder resin is atomized under normal pressure and water.

  From the viewpoint of lowering the melting point of the binder resin, the amount of the nonionic surfactant used is preferably 5 parts by weight or more with respect to 100 parts by weight of the binder resin, and controls the nonionic surfactant remaining in the toner. From this viewpoint, the amount is preferably 80 parts by weight or less. Therefore, from the viewpoint of making these compatible, the amount of the nonionic surfactant used is preferably 5 to 80 parts by weight, more preferably 10 to 70 parts by weight, and more preferably 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin. Part by weight is more preferred.

  In the step (1), when the primary particles containing the binder resin are produced in the aqueous medium in the presence of the nonionic surfactant, the temperature in the system depends on the dispersibility of the nonionic surfactant and From the viewpoint of preventing a decrease in dispersion efficiency, it is desirable to keep the nonionic surfactant within a temperature range of 10 ° C., preferably 8 ° C., more preferably 5 ° C. above and below the cloud point.

  In step (1), for example, an aqueous medium (preferably deionized water or distilled water) is dropped in a state where the mixture of the binder resin and the nonionic surfactant is stirred and uniformly mixed in the system. It is preferable to do. In the case of using a colorant, it is preferable that the binder resin containing the colorant compatible with the nonionic surfactant is not separated from water.

  The use amount of the aqueous medium is preferably 100 to 3000 parts by weight, more preferably 400 to 3000 parts by weight, more preferably 800 to 3000 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of obtaining uniform aggregated particles in the subsequent steps. Is more preferable.

  The particle size of the primary particles containing a binder resin containing polyester can be controlled by the amount of nonionic surfactant, the degree of stirring, the rate of water addition, and the like. In step (1), the rate at which the aqueous medium is added to the mixture containing at least the binder resin and the nonionic surfactant is preferably 0.1 to 50 g / min per 100 g of the mixture from the viewpoint of obtaining uniform primary particles. 0.5-40 g / min is more preferable, and 1-30 g / min is more preferable.

  In addition, when the binder resin has an acidic group such as a carboxyl group or a sulfone group, water may be added after neutralizing all or part of the binder resin or while neutralizing the binder resin. When using what has an acidic group for binder resin, in addition to the factor of a nonionic surfactant, the self-emulsifying property of resin becomes a control factor of the particle size of a primary particle.

  A dispersant can be used for the purpose of lowering the melt viscosity and melting point of the binder resin and improving the dispersibility of the primary particles produced. Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate; sodium dodecylbenzenesulfonate, sodium octadecylsulfate, sodium oleate, Anionic surfactants such as sodium laurate and potassium stearate; Cationic surfactants such as laurylamine acetate, stearylamine acetate and lauryltrimethylammonium chloride; Amphoteric surfactants such as lauryldimethylamine oxide; Tricalcium phosphate, water Examples thereof include inorganic salts such as aluminum oxide, calcium sulfate, calcium carbonate, and barium carbonate. The amount of the dispersant used is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 10 parts by weight or less with respect to 100 parts by weight of the binder resin from the viewpoint of emulsion stability and detergency.

  The solid concentration in the system for preparing the dispersion of primary particles is preferably 7 to 50% by weight, more preferably 7 to 40% by weight, from the viewpoint of the stability of the dispersion and the handling of the dispersion in the aggregation process. %, More preferably 10 to 30% by weight. The solid content includes non-volatile components such as a resin and a nonionic surfactant.

The average primary particle diameter is preferably 0.05 to 3 μm, more preferably 0.05 to 1 μm, and even more preferably 0.05 to 0.8 μm from the viewpoint of uniformly agglomerating in the subsequent step. In the present invention, the average particle size of primary particles refers to the volume median particle size (D ₅₀ ), and can be measured by a laser diffraction type particle size measuring instrument or the like.

  Then, the process (process (2)) which aggregates and unites the primary particle obtained at the process (1) is demonstrated.

  In the step (2), the solid content concentration in the system in which the primary particles are aggregated can be adjusted by adding water to the binder resin dispersion. -50% by weight is preferred, 5-30% by weight is more preferred, and 5-20% by weight is even more preferred.

  The pH in the system in the aggregation step is preferably 2 to 10, more preferably 2 to 9, more preferably 3 to 8, from the viewpoint of achieving both the dispersion stability of the mixed solution and the aggregation properties of fine particles such as a binder resin. Further preferred.

  From the same viewpoint, the temperature in the system in the aggregation step is preferably a softening point of the binder resin of −60 ° C. or more and a softening point or less.

  When the primary particles are aggregated, not only the primary particles obtained in step (1) are aggregated (homo-aggregation), but also a dispersion of resin fine particles obtained in the same manner as in step (1). Etc. may be mixed with a dispersion of primary particles to aggregate the primary particles and other resin fine particles (heteroaggregation).

  In addition, additives such as a colorant and a charge control agent may be premixed in the binder resin when preparing the primary particles, or a dispersion liquid in which each additive is separately dispersed in a dispersion medium such as water. It may be prepared, mixed with primary particles, and subjected to an aggregation process. When the additive is previously mixed with the binder resin when preparing the primary particles, it is preferable to melt and knead the binder resin and the additive in advance. For melt kneading, it is preferable to use an open roll type biaxial kneader. The open roll type twin-screw kneader is a kneader in which two rolls are arranged close to each other in parallel, and a heating function or a cooling function can be imparted by passing a heat medium through each roll. Therefore, the open roll type twin screw kneader is an open type part to be melt kneaded and is provided with a heating roll and a cooling roll. The heat of kneading generated can be easily dissipated.

  In the aggregation process, an aggregating agent can be added in order to effectively perform aggregation. As an aggregating agent, a quaternary salt cationic surfactant, polyethyleneimine, or the like is used in an organic system, and an inorganic metal salt, a divalent or higher metal complex, or the like is used in an inorganic system. Examples of inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, Examples thereof include inorganic metal salt polymers such as calcium sulfide.

  The amount of the flocculant used is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less with respect to 100 parts by weight of the binder resin from the viewpoint of environmental resistance characteristics of the toner.

  The flocculant is preferably added after being dissolved in an aqueous medium, and it is preferable that the flocculant is sufficiently stirred at the time of addition of the flocculant and after completion of the addition.

  Subsequently, the agglomerated particles containing at least the binder resin obtained in the aggregating step are heated and united (a uniting step).

  The temperature in the system in the coalescence process is from the viewpoint of the target toner particle size, particle size distribution, shape control, and particle fusing property, the softening point of the binder resin is −30 ° C. or higher, and the softening point is 10 ° C. or lower. The softening point is -25 ° C or higher and the softening point + 10 ° C or lower is more preferable, and the softening point -20 ° C or higher and the softening point + 10 ° C or lower is more preferable. The stirring speed is preferably a speed at which the aggregated particles do not settle.

  A toner can be obtained by subjecting the coalesced particles obtained in the step (2) to a solid-liquid separation step such as filtration, a washing step, and a drying step as appropriate.

  In the washing step, it is preferable to use an acid in order to remove metal ions on the toner surface in order to ensure sufficient charging characteristics and reliability as the toner. Further, it is preferable to completely remove the added nonionic surfactant by washing, and washing with an aqueous solution below the cloud point of the nonionic surfactant is preferred. The washing is preferably performed a plurality of times.

  In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 3 to 15 μm, more preferably 3 to 10 μm. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. An external additive such as hydrophobic silica may be added to the surface of the toner.

  The toner of the present invention can be used as a one-component developing toner or as a two-component developer mixed with a carrier.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample is heated at a heating rate of 6 ° C / min, and a 1.96 MPa load is applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), weigh 0.01 to 0.02 g of the sample into an aluminum pan, raise the temperature to 200 ° C, and from that temperature to 0 ° C at a rate of 10 ° C / min. The temperature of the cooled sample is raised at a heating rate of 10 ° C / min, and the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent that indicates the maximum slope from the peak rise to the peak apex To do.

[Resin acid value]
Measured according to the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Hydroxyl value of the resin]
Measured according to the method of JIS K0070.

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

Resin production examples 1-6
Equipped with a dehydration tube equipped with a nitrogen introduction tube, a fractionation tube through which hot water is passed at 100 ° C, a stirrer, and a thermocouple with the alcohol component, carboxylic acid component other than trimellitic anhydride and esterification catalyst shown in Table 1 In a 5 liter four-necked flask, kept at 180 ° C. for 1 hour in a nitrogen atmosphere, then heated from 180 ° C. to 230 ° C. at 5 ° C./hour, and then subjected to a condensation polymerization reaction at 220 ° C. for 10 hours, Furthermore, reaction was performed at 230 degreeC and 8.0 kPa for 1 hour. After cooling to 210 ° C., trimellitic anhydride shown in Table 1 was added, reacted at 210 ° C. for 2 hours, reacted to a desired softening point at 210 ° C. and 10 kPa, and polyester (resin A˜ F) was obtained.

Resin production example 7
Place the alcohol component shown in Table 1, carboxylic acid components other than fumaric acid and trimellitic anhydride, and esterification catalyst into a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydrating tube, stirrer and thermocouple. The mixture was reacted at 230 ° C. for 8 hours under a nitrogen atmosphere, cooled to 180 ° C., and then fumaric acid was added. After keeping at 180 ° C. for 1 hour, the temperature was raised from 180 ° C. to 210 ° C. at 10 ° C./hour, followed by condensation polymerization reaction at 210 ° C. for 2 hours and further reaction at 210 ° C. and 8.0 kPa for 1 hour. After cooling to 205 ° C, the trimellitic anhydride shown in Table 1 was added, reacted at 205 ° C for 1 hour, reacted to the desired softening point at 205 ° C and 10 kPa, and polyester (resin G) Got.

Example 1
100 g of resin A 100 g, resin B 100 g and nonionic surfactant (polyoxyethylene lauryl ether (EO = 9 mol addition), cloud point: 98 ° C., HLB: 15.3) in a 5 liter stainless steel container The mixture was melted at 170 ° C. with stirring at 200 r / min. The contents were stabilized at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and sodium hydroxide aqueous solution (concentration: 5% by weight) 75.5 as a neutralizer under stirring at 200r / min with a chi-type stirrer g was added dropwise. Subsequently, deionized water was added dropwise at 6 g / min while stirring at 300 r / min with a Kai-type stirrer, and a total of 1624.5 g was added. During this time, the system temperature was maintained at 95 ° C., and a resin dispersion containing finely divided resin was obtained through a 200 mesh (mesh: 105 μm) wire mesh. The volume median particle size (D ₅₀ ) of the resin particles (primary particles) in the obtained resin dispersion was 0.45 μm, the solid concentration was 12.0% by weight, and no resin component remained on the wire mesh.

  400 g of the obtained resin dispersion (concentration: 12.3 wt%), 40 g of cyan pigment aqueous dispersion (concentration: 5 wt%) and paraffin wax (HNP-9, manufactured by Nippon Seiwa Co., Ltd., melting point: 78 ° C.) 7 g (concentration: 35 wt%, nonionic surfactant: Emulgen 108 (manufactured by Kao Corporation) 5 wt%, wax dispersion diameter (volume median particle size): 0.30 μm) The mixture was mixed at room temperature in a liter container.

  Next, an aqueous solution corresponding to 1 g of calcium chloride is added to this mixture as a flocculant, adjusted to pH = 7 with an aqueous sodium carbonate solution (concentration: 10% by weight), and then at a rotational speed of 5000 r / min using a homomixer. Stir at room temperature for 1 hour. As a result, the obtained mixed dispersion was transferred to a 1 liter autoclave, heated to 90 ° C. and stirred at 500 r / min for 6 hours to form aggregated particles.

Thereafter, the temperature was raised to 100 ° C., and the mixture was further stirred for 1 hour to coalesce the aggregated particles, and then colored resin fine particle powder was obtained through a suction filtration step, a washing step and a drying step. The volume median particle size (D ₅₀ ) of the colored fine resin particle powder was 6.8 μm, and the water content was 0.3% by weight.

1.0 part by weight of hydrophobic silica (TS530, manufactured by Wacker Chemie, number average particle size: 8 nm) is added to 100 parts by weight of the obtained colored resin fine particle powder, and the mixture is externally added using a Henschel mixer. Cyan toner was used. The resulting cyan toner had a volume-median particle size (D ₅₀ ) of 6.8 μm.

Example 2
50 parts by weight of resin C, 50 parts by weight of resin D, 4.0 parts by weight of yellow colorant (Pariotol D1155, manufactured by BASF), 2.5 parts by weight of charge control agent (Bontron E-84, manufactured by Hodogaya Chemical Co., Ltd.) and paraffin wax (HNP -9, Nippon Seiwa Co., Ltd., melting point: 78 ° C.) 4 parts by weight are premixed with a Henschel mixer, melt kneaded with an open roll kneader, cooled, pulverized, and 1 mm of the kneaded product A chip product was obtained.

200 g of the obtained kneaded product and 100 g of nonionic surfactant (polyoxyethylene lauryl ether (EO = 9 mol addition), cloud point: 98 ° C., HLB: 15.3) in a 5 liter stainless steel container The mixture was melted at 170 ° C. with stirring at 200 r / min. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and add sodium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 75.5 g was added dropwise. Subsequently, deionized water was added dropwise at 6 g / min with stirring at 300 r / min with a Kai-type stirrer, and a total of 1624.5 g was added. During this time, the system temperature was maintained at 95 ° C., and a resin dispersion containing finely divided resin was obtained through a 200 mesh (mesh: 105 μm) wire mesh. The volume median particle size (D ₅₀ ) of the resin particles (primary particles) in the obtained resin dispersion was 0.45 μm, the solid concentration was 12.0% by weight, and no resin component remained on the wire mesh.

  Next, an aqueous solution corresponding to 1 g of calcium chloride is added to this mixture as a flocculant, adjusted to pH = 7 with an aqueous sodium carbonate solution (concentration: 10% by weight), and then at a rotational speed of 5000 r / min using a homomixer. Stir at room temperature for 1 hour. The resulting mixed dispersion was transferred to a 1 liter autoclave, heated to 105 ° C. and stirred at 500 r / min for 6 hours to form aggregated particles.

Thereafter, the temperature was raised to 125 ° C., and the mixture was further stirred for 1 hour to coalesce the aggregated particles, and then colored resin fine particle powder was obtained through a suction filtration step, a washing step, and a drying step. Colored volume median particle size of the resin fine particles (D ₅₀₎ is 6.7 .mu.m, the moisture content was 0.3 wt%.

1.0 part by weight of hydrophobic silica (TS530, manufactured by Wacker Chemie, number average particle size: 8 nm) is added to 100 parts by weight of the obtained colored resin fine particle powder, and the mixture is externally added using a Henschel mixer. Yellow toner was used. The resulting yellow toner had a volume-median particle size (D ₅₀ ) of 6.8 μm.

Example 3
600 g of methyl ethyl ketone was put into a 5 L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen introduction tube, and 200 g of resin E was added and dissolved at room temperature. The resulting solution was neutralized by adding 10 g of triethylamine, and then 2000 g of ion exchange water was added, and then methyl ethyl ketone was distilled off at a temperature of 50 ° C. or lower under reduced pressure at a stirring speed of 250 r / min. A self-dispersing aqueous resin particle dispersion (resin content: 9.6% by weight (in terms of solid content)) was obtained. The weight average particle diameter of the polyester particles dispersed in the obtained resin dispersion was 0.3 μm.

  Copper phthalocyanine (manufactured by Dainichi Seika Co., Ltd.) 50 g, nonionic surfactant (Emulgen 150, manufactured by Kao Corporation) 5 g and ion-exchanged water 200 g are mixed, copper phthalocyanine is dissolved, and dispersed using a homogenizer for 10 minutes. Thus, a dispersed colorant dispersion was obtained.

  Paraffin wax (HNP0190, manufactured by Nippon Seiwa Co., Ltd., melting point: 85 ° C) 50 g, cationic surfactant (Sanisol B50, manufactured by Kao Corp.) 5 g and ion-exchanged water 200 g are heated to 95 ° C and homogenizer. Then, the paraffin wax was dispersed using a pressure discharge homogenizer, and a wax dispersion in which the paraffin wax was dispersed with an average particle size of 550 nm was obtained.

  Mix the charge control agent (Bontron E-84, manufactured by Orient Chemical Co., Ltd.) 50 g, nonionic surfactant (Emulgen 150, manufactured by Kao Corporation) and 200 g of ion-exchanged water, use glass beads, sand grinder Was used for dispersion for 10 minutes to prepare a charge control agent dispersion in which the charge control agent was dispersed with an average particle size of 500 nm, and coarse particles remained in the dispersion.

  490 g of the obtained resin particle dispersion, 20 g of the colorant dispersion, 15 g of the wax dispersion, 7 g of the charge control agent dispersion and 2 g of the cationic surfactant (Sanisol B50, manufactured by Kao Corporation) are made of round stainless steel. After mixing and dispersing in the flask using a homogenizer, the flask was heated to 48 ° C. while stirring in the heating oil bath. Furthermore, after maintaining at 48 ° C. for 1 hour, it was confirmed that aggregated particles having a weight average particle diameter of 7.0 μm were formed.

After adding 3 g of an anionic surfactant (Perex SS-L, manufactured by Kao Corporation) to the aggregated particle dispersion in which aggregated particles are formed, a reflux tube is attached to the stainless steel flask and stirring is continued. While heating to 80 ° C. at a rate of 5 ° C./min and holding for 5 hours, the aggregated particles were coalesced and fused. Thereafter, the mixture was cooled, the fused particles were filtered, washed thoroughly with ion-exchanged water, and then dried, whereby the volume median particle size (D ₅₀ ) of the obtained colored resin fine particle powder was 7.1 μm.

1.0 part by weight of hydrophobic silica (TS530, manufactured by Wacker Chemie, number average particle size: 8 nm) is added to 100 parts by weight of the obtained colored resin fine particle powder, and the mixture is externally added using a Henschel mixer. Cyan toner was used. The resulting cyan toner had a volume-median particle size (D ₅₀ ) of 7.1 μm.

Example 4
A cyan toner was obtained in the same manner as in Example 1 except that 50 parts by weight of resin A and 50 parts by weight of resin F were used instead of resin A. The obtained cyan toner had a volume-median particle size (D ₅₀ ) of 6.7 μm.

Comparative Example 1
A cyan toner was obtained in the same manner as in Example 1 except that 100 parts by weight of the resin G was used instead of the resin A. The resulting cyan toner had a volume-median particle size (D ₅₀ ) of 6.8 μm.

Comparative Example 2
A cyan toner was obtained in the same manner as in Example 1 except that 100 parts by weight of the resin F was used instead of the resin A. The obtained cyan toner had a volume-median particle size (D ₅₀ ) of 6.7 μm.

Test Example 1 [Hydrolysis resistance]
1.0 g of the binder resin used in each example and comparative example shown in Table 2 is placed in a 100 ml eggplant flask, 20 ml of a 0.1 mol / L potassium hydroxide methanol solution is added thereto, and further 20 ml of distilled water is added. Was added in a 90 ° C. water bath for 5 hours. After heating for 5 hours, the solution was neutralized with 0.1 mol / L hydrochloric acid, the solvent was removed, and the remaining resin was dried. The glass transition point (Tg) of the obtained resin was measured, Tg before and after the test was compared, and hydrolysis resistance was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
4: Tg temperature difference between before and after the test is less than 1 ° C 3: Tg temperature difference between before and after the test is between 1 ° C and less than 3 ° C 2: Tg temperature difference between before and after the test is between 3 ° C and less than 6 ° C 1: Temperature difference of Tg before and after the test is 6 ℃ or more

Test Example 2 [low temperature fixability]
Fixing machine (fixing speed 390mm / sec) with improved fixing machine of copying machine "AR-505" (manufactured by Sharp Corporation) so that it can be fixed outside the machine and adjusted to a total fixing pressure of 40kgf ), A fixing test of unfixed images was performed at each temperature while increasing the temperature by 10 ° C. from 100 ° C. to 240 ° C. “UNICEF Cellophane” (Mitsubishi Pencil Co., Ltd., width: 18 mm, JISZ-1522) was pasted on the fixed image, passed through a fixing roller set at 30 ° C., and then the tape was peeled off. Measure the optical reflection density before and after applying the tape using a reflection densitometer “RD-915” (manufactured by Macbeth Co.), and the ratio of both (after peeling / before sticking) first exceeds 90%. The temperature of the roller was set to the minimum fixing temperature, and the low temperature fixing property was evaluated according to the following evaluation criteria. The results are shown in Table 2. The paper used for the fixing test is CopyBond SF-70NA (75 g / m ² ) manufactured by Sharp Corporation.

〔Evaluation criteria〕
3: The minimum fixing temperature is less than 140 ° C.
2: The minimum fixing temperature is 140 ° C. or higher and lower than 160 ° C.
1: The minimum fixing temperature is 160 ° C. or higher.

Test Example 3 [Hot offset resistance]
In Test Example 2, when the temperature of the fixing roll is sequentially increased from 90 ° C. to 240 ° C., the temperature at which offset is first confirmed is visually determined, and the hot offset resistance is evaluated according to the following evaluation criteria. did. The results are shown in Table 2.
〔Evaluation criteria〕
4: Hot offset generation temperature is 220 ° C or higher 3: Hot offset generation temperature is 200 ° C or higher and lower than 220 ° C 2: Hot offset generation temperature is 180 ° C or higher and lower than 200 ° C 1: Hot offset generation temperature is lower than 180 ° C

Test Example 4 [Preservability]
4 g of toner was left for 72 hours in an environment at a temperature of 55 ° C. and a humidity of 60%. After standing, the degree of toner aggregation occurrence was visually observed, and storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
4: No aggregation was observed after 48 hours and 72 hours.
3: Aggregation is not observed after 48 hours, but slight aggregation is observed after 72 hours.
2: Aggregation is not observed after 48 hours, but aggregation is clearly observed after 72 hours.
Aggregation is already observed within 1:48 hours.

  From the above results, the toners of Examples 1 to 4 containing a polyester in which an appropriate amount of an aliphatic polyhydric alcohol having two or more secondary carbon atoms having a hydroxyl group bonded thereto are used. It can be seen that the film has good storage stability and low-temperature fixability.

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

Claims (6)

  A toner obtained by a method including a step of granulating a raw material containing polyester in an aqueous medium, wherein the polyester is an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms to which a hydroxyl group is bonded. An electrophotographic toner, which is a polyester obtained by polycondensation of an alcohol component containing 20 to 100 mol% and a carboxylic acid component.   The alcohol A is an aliphatic polyhydric alcohol having 4 to 8 carbon atoms and having one or more pairs of secondary carbon atoms in which secondary carbon atoms bonded with hydroxyl groups are adjacent to each other. Toner for electrophotography.   The toner for electrophotography according to claim 1 or 2, wherein the alcohol component further contains an aliphatic diol having 2 to 6 carbon atoms other than alcohol A.   The toner for electrophotography according to any one of claims 1 to 3, wherein the carboxylic acid component contains 0.1 to 30 mol% of a trivalent or higher polyvalent carboxylic acid compound.   The step of granulating the raw material in an aqueous medium includes the step (1) of generating primary particles containing a binder resin containing polyester in an aqueous medium in the presence of a nonionic surfactant, and the primary particles The toner for electrophotography according to any one of claims 1 to 4, comprising a step (2) of aggregating and coalescing the toner.   A method for producing an electrophotographic toner comprising a step of granulating a raw material containing polyester in an aqueous medium, wherein the polyester is an aliphatic polyhydric alcohol (alcohol) having two or more secondary carbon atoms to which hydroxyl groups are bonded. A method for producing an electrophotographic toner, which is a polyester obtained by condensation polymerization of an alcohol component containing 20 to 100 mol% of A) and a carboxylic acid component.