JP5320024B2 - Toner for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner having excelling storage property and transfer property, while satisfying excelling low-temperature fixability. <P>SOLUTION: The electrophotographic toner contains a binder resin and an external additive having an average particle diameter of 20 to 250 nm, wherein the binder resin contains a condensation-polymerization resin obtained by the condensation polymerization of a carboxylic acid component and an alcohol component, containing an aliphatic polyhydric alcohol (alcohol A), having two or more secondary carbon atoms to which hydroxyl groups are bonded. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic toner used in electrophotography, electrostatic recording method, electrostatic printing method and the like.

  In recent years, with an increase in machine speed and energy saving, a toner having excellent low-temperature fixability has been demanded. Accordingly, a condensation polymerization resin using an aliphatic polyhydric alcohol has been proposed as a binder resin for toner, instead of the condensation polymerization resin obtained by using an aromatic polyhydric alcohol conventionally used.

  In Patent Document 1, a polyester resin obtained by reacting an alcohol component containing 1,3-propanediol and a specific other polyhydric alcohol as essential components with a polybasic acid component is bound. Disclosed is an electrostatic charge developing toner that is excellent as a fixing resin, has excellent fixability and anti-offset properties, exhibits stable charging behavior even when continuously printed, and has excellent durability to obtain a good high-quality image. Yes.

  Patent Document 2 discloses that a fat having 2 to 6 carbon atoms and having a polyol component of 30 to 100 mol% is provided for the purpose of providing a toner having an excellent balance between low-temperature fixability and grindability and excellent gloss after fixing. A polyester resin for toner using a polyester resin comprising a group diol (at least a part of the aliphatic diol is 1,2-propylene glycol) and having a tetrahydrofuran-soluble component number average molecular weight of 1000 to 9500 is disclosed. Yes.

Patent Document 3 discloses that toner particles and a specific average particle size have at least 2 to improve transfer efficiency while maintaining high resolution and image density and to stabilize toner fluidity. An electrophotographic toner comprising various types of external additives is disclosed.
JP 2002-169331 A JP 2006-154686 A JP-A-6-332235

  However, polyesters obtained using aliphatic polyhydric alcohols are excellent in low-temperature fixability, but are insufficient in preservability and transferability.

  An object of the present invention is to provide an electrophotographic toner that is excellent in storage stability and transferability while satisfying excellent low-temperature fixability.

  The present invention includes a condensation polymerization resin obtained by condensation polymerization of an alcohol component containing an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms having a hydroxyl group bonded thereto and a carboxylic acid component. The present invention relates to an electrophotographic toner comprising a binder resin and an external additive having an average particle diameter of 20 to 250 nm.

  The toner for electrophotography of the present invention exhibits the effect of being excellent in storage stability and transferability while satisfying excellent low-temperature fixability.

  The electrophotographic toner of the present invention is a polycondensation of an alcohol component containing an aliphatic polyhydric alcohol (alcohol A) having two or more secondary carbon atoms bonded with a hydroxyl group and a carboxylic acid component as a binder resin. It is characterized in that it contains a polycondensation resin obtained. Polycondensation-based resins obtained using aliphatic polyhydric alcohols tend to have higher ester values compared to the case of using aromatic polyhydric alcohols such as alkylene oxides of bisphenol A that are generally used. Therefore, it is effective in improving the low-temperature fixability from the viewpoint of compatibility with paper. On the other hand, when the molecular skeleton is soft and the molecular weight is not increased so much, it is difficult to increase the glass transition point, which causes a decrease in storage stability and transferability. However, in the present invention, the use of the aliphatic polyhydric alcohol having the above specific structure makes it possible to improve the storage stability and transferability without impairing the low-temperature fixability. This is because the alkyl group bonded to the secondary carbon to which the hydroxyl group is bonded constrains the mobility of the molecule, and therefore has a higher glass transition point than a resin with a similar softening point. One is estimated. That is, it is presumed that the storage stability is improved by having a high glass transition point, and the transferability is improved by reducing the embedding of the external additive into the resin due to mechanical stress. Furthermore, the transferability is significantly improved by using an external additive having an average particle diameter of 20 to 250 nm. This is presumably because a suitable spacer effect is developed between the toner and the equipment.

  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 alcohol A is preferably 4-8, more preferably 4-5, and even more preferably 4 from the viewpoint of increasing the ester value, improving the low-temperature fixability of the toner and improving the storage stability. In addition, from the viewpoint of improving the storage stability by making the main chain skeleton of the resin rigid, an aliphatic polyhydric alcohol having one or more pairs of secondary carbon atoms in which secondary carbon atoms bonded with hydroxyl groups are adjacent to each other is more suitable. 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.

  The content of the alcohol A is preferably 10 to 100 mol%, more preferably 12 to 80 mol%, and further preferably 25 to 75 mol% in the alcohol component from the viewpoint of low-temperature fixability and storage stability of the toner.

  The amount of alcohol A used in the condensation polymerization of the alcohol component and the carboxylic acid component is selected from the viewpoints of low-temperature fixability and storage stability of the toner, and the alcohol component other than alcohol A, which is a raw material monomer for the condensation polymerization resin. And 6-100 weight part is preferable with respect to 100 weight part of total amounts of a carboxylic acid component, 10-90 weight part is more preferable, 15-80 weight part is further more preferable.

  In the present invention, from the viewpoint of low-temperature fixability of the toner, the alcohol component further contains an aliphatic diol (alcohol B) having 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms other than alcohol A. It is preferable. 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. Among these, ethylene glycol, 1,2-propanediol and 1,3-propanediol are preferable from the viewpoint of storage stability of the toner.

  The content of the alcohol B is preferably 0 to 90 mol%, more preferably 0.5 to 90 mol%, still more preferably 20 to 88 mol%, and more preferably 25 to 75 in the alcohol component from the viewpoint of improving the low-temperature fixability of the toner. Mole% is even more preferred.

  The content of alcohol B relative to 1 mol of alcohol A is preferably 10 mol or less, preferably 0.1 to 5 mol, more preferably 0.3 to 3 mol, from the viewpoint of low-temperature fixability and storage stability of the toner.

  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 and OR are oxyalkylene groups, R is an ethylene and / or propylene group, x and y indicate the number of added moles of alkylene oxide, each being a positive number, and the sum of x and y. 1 to 16 is preferable, 1 to 8 is more preferable, and 1.5 to 4 is more preferable)
An aromatic diol such as an alkylene oxide adduct of bisphenol represented by the formula: a trihydric or higher polyhydric alcohol such as glycerin.

  From the viewpoint of low-temperature fixability of the toner, the content of the aromatic diol is preferably 10 mol% or less, more preferably 5 mol% or less in the alcohol component, and it is preferable that the aromatic diol is not substantially used. Here, “not substantially used” means that the content is 0 mol% in the alcohol component or 1 mol% or less even if it is contained.

  As the carboxylic acid component, a dicarboxylic acid compound or a trivalent or higher polyvalent carboxylic acid compound can be used.

  Dicarboxylic acid compounds include aliphatic acids such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, alkyl succinic acid and alkenyl succinic acid. Dicarboxylic acids; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. In the present invention, the above-mentioned acids, anhydrides of these acids, and alkyl esters of the acids are collectively referred to herein as carboxylic acid compounds.

  Examples of the trivalent or higher polyvalent carboxylic acid compound include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and other aromatic carboxylic acids, and these Derivatives such as acid anhydrides and alkyl (C1-3) esters are exemplified.

  Other acids include rosin; rosin modified with fumaric acid, maleic acid, acrylic acid, and the like.

  In the present invention, the carboxylic acid component is a trivalent or higher polyvalent carboxylic acid compound, preferably a trimellitic acid compound, more preferably a trimaleic anhydride compound, from the viewpoint of increasing the molecular weight of the resin and improving the low-temperature fixability and storage stability of the toner. It is desirable to contain merit acid. The content of the trivalent or higher polyvalent carboxylic acid compound is preferably 0.1 to 30 mol%, more preferably 1 to 25 mol%, and even more preferably 5 to 25 mol% in the carboxylic acid component of the condensation polymerization resin.

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

  The polycondensation reaction between the alcohol component and the carboxylic acid component can be performed in an inert gas atmosphere in the presence of an esterification catalyst such as a tin compound and a titanium compound, a polymerization inhibitor, and the like. ~ 250 ° C is preferred.

  As the tin compound, for example, dibutyltin oxide is known. However, in the present invention, tin (II) having no Sn—C bond is used from the viewpoint of good dispersibility in the condensation polymerization resin. Compounds are preferred.

  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. Among these, from the viewpoint of catalytic ability, (R ¹ COO) ₂ Sn (wherein R ¹ represents an alkyl group or alkenyl group having 5 to 19 carbon atoms), fatty acid tin (II), (R ² O) ₂ Sn (where R ² is carbon number 6) ~ 20 alkyl or alkenyl groups Alkoxy tin (II) and tin oxide represented by SnO (II) is preferably represented by the be), (R ¹ COO) is more preferably a fatty acid tin represented by ₂ Sn (II) and tin oxide (II) Further preferred are tin (II) octoate, tin (II) 2-ethylhexanoate, tin (II) stearate and tin (II) oxide.

  As the titanium compound, a titanium compound having a Ti-O bond is preferable, and a compound having an alkoxy group having 1 to 28 carbon atoms, an alkenyloxy group having 2 to 28 carbon atoms, or an acyloxy group having 1 to 28 carbon atoms in total is preferable. 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 said tin (II) compound and titanium compound can be used 1 type or in combination of 2 or more types.

  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 the present invention, examples of the condensation polymerization resin include polyester, polyester / polyamide, and the like. Among these, polyester is preferable from the viewpoint of durability and chargeability of the toner.

  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 polyester / polyamide is obtained by using a raw material monomer for forming an amide component in addition to the alcohol component and the carboxylic acid component, and subjecting these raw material monomers to condensation polymerization. Examples of the raw material monomer for forming the amide component include various known polyamines, aminocarboxylic acids, amino alcohols and the like.

  The binder resin may be a composite resin including a condensation polymerization resin and an addition polymerization resin such as a vinyl resin, and the composite resin is a mixture of the condensation polymerization resin and the addition polymerization resin. However, a resin obtained by polymerizing the raw material monomer of the condensation polymerization resin and the raw material monomer of the addition polymerization resin in the same reaction vessel is preferable.

  Furthermore, in addition to the raw material monomer of the condensation polymerization resin and the raw material monomer of the addition polymerization resin, the composite resin is used for addition polymerization in the condensation polymerization resin component by using a bireactive monomer that can react with any of them. A hybrid resin in which the resin component is more finely and uniformly dispersed is preferable. Both reactive monomers have at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or carboxyl. Group, more preferably a compound having a carboxyl group and an ethylenically unsaturated bond, and examples thereof include acrylic acid, methacrylic acid, and fumaric acid. In addition, when calculating content of the alcohol A with respect to the total amount of alcohol components other than the alcohol A and the carboxylic acid component, the amount of the both reactive monomers is included in the alcohol component and the carboxylic acid component as a raw material monomer of the condensation polymerization resin.

  In the present invention, the softening point of the binder resin is preferably 90 to 160 ° C., more preferably 95 to 155 ° C., and further preferably 115 to 150 ° C. from the viewpoints of low-temperature fixability, storage stability and durability of the toner.

  In general, the softening point of the resin and the glass transition point are correlated. However, since the condensation polymerization resin can increase the glass transition point compared to a resin having the same degree of softening point, even one type of resin satisfies the low-temperature fixability and storage stability of the toner. However, by using a resin having a high softening point and a resin having a low softening point in combination, the above point is more excellent. Specifically, from the above viewpoint, the polycondensation resin preferably comprises a high softening point resin and a low softening point resin, each having a softening point of preferably 10 ° C. or higher, more preferably 20 to 60 ° C. The softening point of the high softening point resin is preferably 125 to 160 ° C, more preferably 130 to 150 ° C, and the softening point of the low softening point resin is preferably 90 to 120 ° C, more preferably 90 to 110 ° C. is there. The weight ratio of the high softening point resin to the low softening point resin (high softening point resin / low softening point resin) is preferably 1/3 to 3/1, and more preferably 1/2 to 2/1.

  The glass transition point of the binder resin is preferably 45 to 85 ° C., more preferably 50 to 80 ° C., and further preferably 58 to 75 ° C. from the viewpoints of low-temperature fixability, storage stability and durability of the toner. From the viewpoint of the chargeability and environmental stability of the toner, the acid value is preferably from 1 to 90 mgKOH / g, more preferably from 5 to 90 mgKOH / g, and even more preferably from 5 to 88 mgKOH / g.

  The toner of the present invention includes known binder resins other than the above condensation polymerization resins, for example, vinyl resins such as polyester and styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, as long as the effects of the present invention are not impaired. However, the content of the polycondensation resin is preferably 30% by weight or more, more preferably 50% by weight or more, and further preferably 70% by weight or more in the total binder resin. 80% by weight or more is more preferable, 90% by weight or more is more preferable, and substantially 100% by weight is further preferable.

  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 dyes and pigments used as toner colorants can be used. Carbon black, black pigment, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine- B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Isoindoline, Disazo yellow and the like can be used alone or in combination of two or more. The toner 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.

  Examples of the charge control agent include chromium-based azo dyes, iron-based azo dyes, aluminum azo dyes, salicylic acid metal complexes, and the like, and these can be used alone or in admixture of two or more.

  The content of the charge control agent is preferably 0.1 to 8 parts by weight and more preferably 0.5 to 7 parts by weight with respect to 100 parts by weight of the binder resin.

  Release agents include polyolefin wax, paraffin wax, silicones; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; carnauba wax, rice wax, candelilla wax, wood wax, jojoba Plant waxes such as oils; animal waxes such as beeswax; waxes such as mineral and petroleum waxes such as montan wax, ozokerite, ceresin, microcrystalline wax, and Fischer-Tropsch wax, which are used alone or in combination of two or more Can be mixed and used.

  The melting point of the release agent is preferably 60 to 160 ° C., more preferably 60 to 150 ° C., from the viewpoints of low-temperature fixability and offset resistance of the toner.

  The content of the release agent is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, and more preferably 1.5 to 7 parts by weight from the viewpoint of dispersibility in the binder resin with respect to 100 parts by weight of the binder resin. Part by weight is more preferred.

  As the external additive used in the present invention, inorganic fine particles are preferable, and at least one selected from the group consisting of silica, alumina, titania, zirconia, tin oxide, and zinc oxide is preferable. Among these, silica From the viewpoint of preventing embedding, it is more preferable that silica having a low specific gravity is contained.

  Silica is preferably hydrophobic silica that has been subjected to a hydrophobic treatment, from the viewpoint of toner transferability.

  As a method for hydrophobizing silica, silanol groups on the surface of silica particles are preferably modified with a hydrophobic group such as an alkylsilyl group having 1 to 12 carbon atoms (for example, methylsilyl group, hexylsilyl group, etc.), or It is preferable to coat the surface with a hydrophobic resin.

  Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include organochlorosilane, organoalkoxysilane, organodisilazane, cyclic organopolysilazane, linear organopolysiloxane, and the like. Examples thereof include silazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), methyltriethoxysilane, and the like. Among these, hexamethyldisilazane is preferable.

  Examples of the method for substituting the silanol group on the surface of the silica particles with a hydrophobic group such as an alkylsilyl group include a method of reacting a water-dispersed silica colloid with an alkylsilanol alkali metal salt (see Japanese Patent Publication No. 7-33250); water A method in which an organic solvent, a cationic surfactant, and an alkyltrialkoxysilane are added to the dispersed silica colloid, followed by azeotropic dehydration, followed by heating to reflux (see JP-A-6-73389); wet silica or alkyl on dry silica Examples thereof include a method of reacting trialkoxysilane, an organic silicon halide compound and the like (see JP-A-6-206720, JP-A-7-187647, etc.).

  In the silica in which at least a part of the silanol groups on the surface of the silica particles is substituted with hydrophobic groups to be hydrophobized, the silanol groups on the surface of the silica particles are preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably It is desirable that 20 mol% or more is substituted with a hydrophobic group.

Since the silanol groups on the surface of the silica particles can ionically adsorb amino groups and imino groups, the ratio of silanol groups modified by the hydrophobic groups is, for example, before and after the modification reaction. This can be determined by measuring the amount of di-n-butylamine adsorbed on silica. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per silica surface area.

  The average particle diameter of the external additive is 20 to 250 nm, preferably 30 to 200 nm, and more preferably 35 to 90 nm, from the viewpoint of the chargeability, fluidity, and transferability of the toner. If the average particle diameter of the external additive is less than 20 nm, the distance between the toner particles and the machine is too short, so that the toner particles are likely to adhere to the machine, and the transferability is lowered. On the other hand, if it exceeds 250 nm, the distance between the toner particles and the machine is too large, so that the toner particles and the machine hardly come into contact with each other, and the transferability is lowered.

  The content of the external additive is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably 0.3 to 100 parts by weight of toner particles before being processed with the external additive. ~ 3 parts by weight.

  The toner particles may be obtained by any conventionally known method such as a melt kneading method, an emulsion phase inversion method, or a polymerization method. However, from the viewpoint of productivity and dispersibility of the colorant, the toner particles are melt kneaded. The toner ground by the method is preferred. In the case of pulverized toner by the melt-kneading method, for example, after a raw material such as a binder resin, a colorant, a charge control agent, and a release agent is uniformly mixed with a mixer such as a Henschel mixer, a sealed kneader, uniaxial or 2 It can be manufactured by melt-kneading with a shaft extruder, open roll type kneader or the like, cooling, pulverizing and classifying. On the other hand, from the viewpoint of reducing the particle size of the toner, a toner by a polymerization method is preferable.

The volume median particle size (D ₅₀ ) of the toner particles 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.

  The toner of the present invention is obtained by mixing toner particles and an external additive. For mixing the toner particles and the external additive, it is preferable to use a stirrer having a stirrer such as a rotary blade. A particularly suitable stirrer is a Henschel mixer.

  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.

[Acid value of the resin]
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)).

[Melting point of release agent]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C, and the sample was cooled to 0 ° C at a temperature drop rate of 10 ° C / min. The maximum peak temperature of heat of fusion is taken as the melting point.

[Volume-median particle diameter of toner particles (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).

[Average particle size of external additives]
The average particle diameter refers to the number average particle diameter, which is the average value of the particle diameters of 500 particles measured from a scanning electron microscope (SEM) photograph of the external additive. When there is a major axis and a minor axis, the major axis is indicated.

Resin production example 1 [resins A to E]
Polyester raw material monomers and esterification catalysts other than trimellitic anhydride shown in Table 1 were equipped with a nitrogen introduction pipe, a dehydration pipe equipped with a fractionation pipe through which hot water of 100 ° C was passed, a stirrer and a thermocouple. In a 4-liter flask with a volume of 1 liter, kept at 180 ° C. for 1 hour in a nitrogen atmosphere, then heated from 180 ° C. to 230 ° C. at a rate of 10 ° C./hour, and then subjected to a condensation polymerization reaction at 230 ° C. for 10 hours. The reaction was performed at ° C and 8.0 kPa for 1 hour. After cooling to 210 ° C, the trimellitic anhydride shown in Table 1 was added and reacted at 210 ° C for 2 hours, and at 210 ° C and 10 kPa until the desired softening point was reached, polyester was obtained. It was.

Resin Production Example 2 [Resin F]
Put polyester raw material monomer and esterification catalyst other than trimellitic anhydride shown in Table 1 into a 5-liter four-necked flask equipped with a dehydration tube equipped with a nitrogen introduction tube, a stirrer and a thermocouple, and a nitrogen atmosphere. Then, a condensation polymerization reaction was carried out at 230 ° C. for 10 hours, and further a reaction was carried out at 230 ° C. and 8.0 kPa for 1 hour. Further, trimellitic anhydride shown in Table 1 was reacted at 210 ° C. and reacted at 10 kPa until a desired softening point was reached, thereby obtaining a polyester.

Examples 1-5 and Comparative Examples 1-4
Binder resin 100 parts by weight shown in Table 2, magenta pigment “Super Magenta R” (Dainippon Ink Chemical Co., Ltd., PR122) 6 parts by weight, negative charge control agent “Bontron S-34” (Orient Chemical Co., Ltd.) 1 part by weight and 2 parts by weight of paraffin wax “HNP-9” (manufactured by Nippon Seiki Co., Ltd., melting point: 75 ° C.) are thoroughly mixed with a Henschel mixer, and then rotated using a co-rotating twin screw extruder. It was melt-kneaded at a heating temperature of 80 ° C. in a roll at 200 r / min. The obtained melt-kneaded product was cooled, coarsely pulverized, then pulverized by a jet mill, and classified to obtain toner particles having a volume median particle size (D ₅₀ ) of 8.0 μm.

  1.0 part by weight of each of the external additives shown in Table 2 was added to 100 parts by weight of the obtained toner particles, and mixed with a Henschel mixer for 3 minutes to obtain a toner.

Test Example 1 [low temperature fixability]
Toner was mounted in an apparatus in which the fixing machine of the copier “AR-505” (manufactured by Sharp Corporation) was modified so that fixing was possible outside the apparatus, and an unfixed image was obtained. Using a fixing machine (fixing speed 390mm / sec) adjusted so that the total fixing pressure is 40kgf, the temperature of the fixing roller is gradually increased from 100 ° C to 240 ° C in 10 ° C increments. A fixing test was conducted. “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. The optical reflection density before and after the tape was peeled off was measured using a reflection densitometer “RD-915” (manufactured by Macbeth), and the ratio between the two (after peeling / before sticking × 100) was initially 90%. The fixing roller temperature exceeding the minimum fixing temperature was used, and the low temperature fixing property was evaluated according to the following evaluation criteria. The results are shown in Table 2. The paper used in the fixing test was CopyBond SF-70NA (75 g / m ² ) manufactured by Sharp Corporation.

〔Evaluation criteria〕
A: The minimum fixing temperature is less than 150 ° C.
B: The minimum fixing temperature is 150 ° C. or higher and lower than 170 ° C.
C: The minimum fixing temperature is 170 ° C. or higher.

Test Example 2 [Preservation]
4 g of toner was placed in a 20 ml container (diameter: about 3 cm) and left for 72 hours in an environment of 55 ° C. and 60% humidity. After standing, the degree of occurrence of toner aggregation was visually observed, and storage stability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
A: Aggregation is not observed at all after 48 hours and 72 hours.
B: Aggregation is not observed after 48 hours, but slight aggregation is observed after 72 hours.
C: Aggregation is not observed after 48 hours, but aggregation is clearly observed after 72 hours.
D: Aggregation is observed within 48 hours.

Test Example 3 [Transferability]
A solid image was printed by mounting toner on a color printer "MICROLINE 5400" (Oki Data). At this time, the amount of toner on the photoconductor for the solid image is adjusted to 0.40 to 0.50 mg / cm ² , the machine is stopped during the printing of the solid image, and the mending tape is applied to the photoconductor after passing through the transfer portion. Then, the toner that was not transferred and remained on the photoconductor was transferred to a mending tape, and the mending tape was peeled off from the photoconductor. The hue of peeled and unused mending tape was measured with “CR-321” (Minolta Co., Ltd.). Based on the color difference ΔE calculated from the following formula, transferability was measured according to the following evaluation criteria. Evaluated. The results are shown in Table 2.

(In the formula, L ₁ ^* , a ₁ ^* and b ₁ ^* are the measured values of the peeled mending tape, and L ₂ ^* , a ₂ ^* and b ₂ ^* are the measured values of the unused mending tape. Respectively.)

〔Evaluation criteria〕
A: Color difference ΔE is less than 3.0 B: Color difference ΔE is 3.0 or more and less than 4.0 C: Color difference ΔE is 4.0 or more

  From the above results, the toner of Comparative Example 1 containing a binder resin using an aliphatic polyhydric alcohol other than the alcohol A compared with the toners of Examples 1 to 5 has good low-temperature fixability. It can be seen that the toner of Comparative Example 2, which lacks storage and transferability and contains a binder resin using an aromatic polyhydric alcohol, has insufficient performance. In addition, both the toner of Comparative Example 3 using an external additive having an average particle size that is too small and the toner of Comparative Example 4 using an external additive having an average particle size that is too large have a significant decrease in transferability. I understand.

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

Claims (5)

A condensation polymerization resin obtained by condensation polymerization of an alcohol component containing 10 to 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 An electrophotographic toner comprising a binder resin containing, and an external additive having an average particle diameter of 20 to 250 nm , wherein the carboxylic acid component is a trivalent or higher polyvalent carboxylic acid compound. An electrophotographic toner containing a mol%.   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. The toner for electrophotography as described.   The amount of alcohol A used in the condensation polymerization of the alcohol component and carboxylic acid component is 6 to 100 parts by weight with respect to 100 parts by weight of the total amount of alcohol components and carboxylic acid components other than alcohol A. Or the toner for electrophotography of 2. The toner for electrophotography according to any one of claims 1 to 3 , wherein the alcohol component further contains an aliphatic diol having 2 to 8 carbon atoms other than alcohol A. The electrophotographic toner according to any one of claims 1 to 4, wherein the acid value of the condensation polymerization resin is 5 to 90 mgKOH / g.