JP2010286592A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner with superior low-temperature fixability, preservability and electrostatic chargeability. <P>SOLUTION: The electrophotographic toner includes a binder resin including a polyester obtained by condensation polymerization of an alcohol component and a carboxylic acid component including a carboxylic acid compound having a pyridine skeleton in a molecule, and a positive charge type charge control resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In recent years, as the speed of printers and copiers has increased, toners with excellent low-temperature fixability have been demanded, and there is a tendency to lower the molecular weight of the resin. A point is desired.

  In order to achieve both of these properties, polyesters obtained using aromatic compounds (compounds containing a benzene ring) have been studied. For example, Patent Document 1 discloses that an alcohol component containing 50 mol% or more of an ethylene oxide adduct of bisphenol A in a total alcohol component, terephthalic acid, 80 mol% or more in a divalent carboxylic acid component, and a total carboxylic acid. A binder resin for toner containing a polyester obtained by polycondensation with a carboxylic acid component contained in a component at 70 mol% or more and having a softening point of 130 ° C. or more is disclosed.

JP 2005-49766 A

  However, further improvements in low-temperature fixability and chargeability are desired.

  An object of the present invention is to provide an electrophotographic toner excellent in low-temperature fixability, storage stability and chargeability.

  The present invention comprises a binder resin containing a polyester obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing a carboxylic acid compound having a pyridine skeleton in the molecule, and a positively chargeable charge control resin. The present invention relates to an electrophotographic toner.

  The toner for electrophotography of the present invention has the effect of being excellent in low-temperature fixability, storage stability and chargeability.

  The electrophotographic toner of the present invention contains a carboxylic acid compound having a pyridine skeleton in the molecule, and has one feature in that it contains a binder resin containing polyester and a positively chargeable charge control resin. Thus, the toner has excellent low-temperature fixability, storage stability and chargeability. That is, it has been found that the toner of the present invention is excellent in the storage stability of the toner, as well as the polyester having a benzene ring, and is excellent in the low-temperature fixability and the charging property of the toner. This is because the nitrogen atom is inserted into the benzene ring of the polyester used as the binder resin, so that the glass transition point is lowered appropriately compared to the polyester having a benzene ring. Further, it is presumed that the chargeability is excellent by improving the dispersibility of the positively chargeable charge control resin.

  Examples of carboxylic acid compounds having a pyridine skeleton in the molecule include picolinic acid, sodium picolinate, 3-hydroxypicolinic acid, 3-carbamoylpicolinic acid, 6-methylpicolinic acid, 3-n-propoxypicolinic acid, and 6-quinolinecarboxylic acid. Monocarboxylic acids such as acid, isoquinoline-1-carboxylic acid, isoquinoline-3-carboxylic acid monohydrate, 4-hydroxyquinoline-2-carboxylic acid (quinurenic acid), quinaldic acid, sodium quinaldate, xanthurenic acid or the like Lower alkyl (1 to 3 carbon atoms) ester of 2,6-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid hydrate, 2,5-pyridinedicarboxylic acid, 2,3-pyridinedicarboxylic acid, 4-hydroxy Dicarboxylic acids such as pyridine-2,6-dicarboxylic acid (chelidamic acid) monohydrate, 2,6-diacetylpyridine, 3,5-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, etc. Phosphate or their lower alkyl esters thereof (C1 to C3). In the present invention, the carboxylic acid compound is generically referred to as including carboxylic acid, acid anhydride, alkyl ester derivatives and the like. Of these, dicarboxylic acid compounds are preferred from the viewpoints of low-temperature fixability, storage stability, and condensation polymerization reactivity.

  The content of the carboxylic acid compound having a pyridine skeleton in the molecule is preferably 20 mol% or more, more preferably 30 to 90 mol%, more preferably 40 to 80 mol in the carboxylic acid component, from the viewpoint of low-temperature fixability and storage stability. % Is more preferable.

  The polyester contained as the binder resin is obtained by polycondensing a carboxylic acid component containing a carboxylic acid compound having a pyridine skeleton in the molecule and an alcohol component.

  As the alcohol component, the formula (I):

(Wherein R ¹ O and OR ¹ are oxyalkylene groups, R ¹ is an ethylene and / or propylene group, x and y indicate the number of added moles of alkylene oxide, each being a positive number, The average value of the sum of y and y is preferably 1-16, more preferably 1-8, and even more preferably 1.5-5)
An alkylene oxide adduct or aliphatic diol of bisphenol A represented by

  The alkylene oxide adduct of bisphenol A is preferable from the viewpoint of storage stability.

  Specific examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane and 2,2-bis (4-hydroxy). And an alkylene oxide adduct of bisphenol A such as a polyoxyethylene adduct of phenyl) propane.

  From the above viewpoint, the content of the alkylene oxide adduct of bisphenol A is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, and still more preferably 50 to 100 mol% in the alcohol component.

  An aliphatic diol, preferably an aliphatic diol having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, is preferable from the viewpoint of low-temperature fixability of the toner.

  Aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 1,4-butenediol, neopentyl glycol, 2,3-butanediol, 2,3-pentanediol, 2,4-pentanediol, 2,3-hexanediol, 3,4- Examples include hexanediol, 2,4-hexanediol, and 2,5-hexanediol.

  Among these, an aliphatic diol having a hydroxyl group bonded to a secondary carbon atom is preferable from the viewpoint of excellent low-temperature fixability and storage stability of the toner. The carbon number of the aliphatic diol is preferably 3 to 8 carbon atoms, more preferably 3 to 6 carbon atoms, from the viewpoint of low-temperature fixability and storage stability of the toner. Specifically, 1,2-propanediol, 2,3-butanediol, 2,3-pentanediol, 2,4-pentanediol, 2,3-hexanediol, 3,4-hexanediol, 2,4 -Hexanediol, 2,5-hexanediol and the like.

  From the above viewpoint, the content of the aliphatic diol is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, and still more preferably 50 to 100 mol% in the alcohol component.

  As carboxylic acid components other than carboxylic acid compounds having a pyridine skeleton in the molecule, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, adipic acid, sebacic acid, azelaic acid, succinic acid (For example, substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isooctenyl succinic acid, isooctyl succinic acid, etc. Aliphatic dicarboxylic acids such as succinic acid; phthalic acid, isophthalic acid, terephthalic acid, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, etc. Aromatic polycarboxylic acids such as cycloaliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, rosin, fumaric acid, maleic acid, acrylic acid, etc. Sex rosin, etc. and anhydrides and lower alkyl of these acids (1-3 carbon atoms) esters, and the like.

  Among these, an aromatic polyvalent carboxylic acid compound is preferable from the viewpoint of the storage stability of the toner, and the viewpoint of improving the storage stability of the toner and the reactivity of the condensation polymerization reaction of the carboxylic acid compound having a pyridine skeleton in the molecule. Therefore, trimellitic acid, pyrrolmet acid, anhydrides of these acids, and trivalent or higher aromatic carboxylic acid compounds such as lower alkyl (C1-3) esters are more preferable.

  The molar ratio of the trivalent or higher aromatic carboxylic acid compound to the carboxylic acid compound having a pyridine skeleton in the molecule (trivalent or higher aromatic carboxylic acid compound / carboxylic acid compound having a pyridine skeleton in the molecule) From the viewpoint of improving the storage stability and the reactivity of the polycondensation reaction of the carboxylic acid compound having a pyridine skeleton in the molecule, 1/10 to 1/1 is preferable, 1/8 to 2/3 is more preferable, and 1/4 ~ 1/2 is more preferred.

  From the viewpoint of low-temperature fixability of the toner, an aliphatic dicarboxylic acid compound is preferable.

  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 molar ratio of the carboxylic acid component and the alcohol component (carboxylic acid component / alcohol component) is preferably from 0.8 to 1.0, more preferably from 0.85 to 0.95, from the viewpoint of increasing the polymerizability, enhancing the storage stability and adjusting the acid value. More preferably 0.85 or more and less than 0.95.

  In the present invention, when a carboxylic acid component containing a carboxylic acid compound other than a carboxylic acid compound having a pyridine skeleton in the molecule is used, the polymerizability of the carboxylic acid compound having a pyridine skeleton in the molecule is increased and the storage stability is improved. From the viewpoint, the carboxylic acid compound having a pyridine skeleton in the molecule and an alcohol component are subjected to condensation polymerization, and after the reaction rate reaches 60 to 98%, more preferably 70 to 95%, another carboxylic acid compound is added. It is preferable to add and perform condensation polymerization. In the present invention, the reaction rate refers to the rate when the discharge of the theoretical reaction water amount is 100%, and in the above case, the theoretical reaction between the carboxylic acid compound having a pyridine skeleton in the molecule and the alcohol component. This is the rate when the amount of water discharged is 100% reaction rate. .

  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 ² COO) ₂ Sn (wherein R ² represents an alkyl group or alkenyl group having 5 to 19 carbon atoms), (R ³ O) ₂ Sn (where R ³ Is C 6-20 alk Alkoxy tin (II) and tin oxide represented by SnO (II) is preferably represented by a group or an alkenyl group), (R ² COO) fatty tin represented by ₂ Sn (II) and tin oxide ( II) is more preferable, and tin (II) octoate, tin (II) 2-ethylhexanoate, tin (II) stearate and tin (II) oxide are more preferable.

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 amount of the esterification catalyst is preferably 0.01 to 2.0 parts by weight, more preferably 0.1 to 1.5 parts by weight, and still more preferably 0.2 to 1.0 parts by weight with respect to 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component. Here, the abundance of the esterification catalyst means the total amount of the catalyst subjected to the condensation polymerization reaction.

  The softening point of the polyester is preferably from 90 to 160 ° C, more preferably from 100 to 150 ° C, and even more preferably from 105 to 145 ° C, from the viewpoint of low temperature fixability, storage stability and durability of the toner.

  Polyester is more excellent in terms of low-temperature fixability and storage stability of toner by using a resin having a high softening point and a resin having a low softening point. Specifically, the binder resin is preferably composed of a high softening point polyester and a low softening point polyester having a softening point of preferably 10 ° C. or higher, more preferably 20 to 60 ° C. from the above viewpoint. The softening point of the high softening point polyester is preferably 125 to 160 ° C, more preferably 130 to 150 ° C, and the softening point of the low softening point polyester is preferably 90 to 120 ° C, more preferably 90 to 110 ° C. is there. The weight ratio of the high softening point polyester to the low softening point polyester (high softening point polyester / low softening point polyester) is preferably 1/3 to 3/1, and more preferably 1/2 to 2/1.

  The glass transition point of the polyester is preferably 45 to 85 ° C, more preferably 50 to 80 ° C, from the viewpoints of low-temperature fixability, storage stability and durability of the toner.

  Further, from the viewpoint of developing charging properties, the acid value is preferably less than 15 mgKOH / g, more preferably 1 mgKOH / g or more and less than 15 mgKOH / g, and further preferably 1 to 13 mgKOH / g. In order to make the acid value less than 15 mgKOH / g, there are methods of adjusting the molar ratio of the carboxylic acid component and the alcohol component used in the condensation polymerization reaction as described above, or adjusting the condensation polymerization reaction of polyester. As the polycondensation reaction proceeds, the molecular weight of the resin increases and the acid value decreases, so the polycondensation reaction may proceed sufficiently.

  The binder resin in the present invention is a resin containing a polyester obtained by condensation polymerization of an alcohol component and a carboxylic acid component, and includes not only a polyester but also a polyester-modified resin. Among these, the durability and charging of the toner are included. From the standpoint of rising properties, polyester is preferred.

  The polyester content is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more in the binder resin.

  The polyester may be a polyester modified to such an extent that the properties are not substantially impaired.

  Examples of the polyester-modified resin include polyester / polyamide, urethane-modified polyester in which polyester is modified with a urethane bond, epoxy-modified polyester in which polyester is modified with an epoxy bond, and two or more kinds including a polyester component and a vinyl resin component. Examples thereof include a composite resin having a resin component.

  The content of the polyester component is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more in the binder resin.

  In the binder resin, other known resins such as vinyl resins such as styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, etc. are used in combination as long as the effects of the present invention are not impaired. However, the content of the polyester in the binder resin is preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and substantially 100% by weight. preferable.

  The toner of the present invention is further characterized in that it contains a positively chargeable charge control resin. When the polyester in the present invention contains a pyridine skeleton, it is considered that the dispersibility of the positively chargeable charge control resin is improved and the positive chargeability is excellent.

  As the positively chargeable charge control resin, an amine-containing resin or a quaternary ammonium base-containing resin is preferable. For example, polyamine resins such as “AFP-B” (manufactured by Orient Chemical Industries); for example, “FCA-701-PT”, “ Examples thereof include quaternary ammonium base-containing styrene acrylic resins such as “FCA-201-PS” (manufactured by Fujikura Kasei Co., Ltd.). Among these, a quaternary ammonium base-containing resin is preferable from the viewpoint of improving positive chargeability.

  As the quaternary ammonium base-containing resin, the formula (II):

(Wherein R ⁴ represents a hydrogen atom or a methyl group)
A monomer represented by the formula (III):

(Wherein R ⁵ represents a hydrogen atom or a methyl group, and R ⁶ represents an alkyl group having 1 to 12 carbon atoms)
And a monomer represented by the formula (IV):

(Wherein R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ and R ⁹ each independently represents an alkyl group having 1 to 4 carbon atoms)
A quaternary ammonium base-containing styrene acrylic resin obtained by polymerization of a monomer mixture containing a monomer represented by the formula (1) or a quaternized product thereof is more preferred. The monomer may be quaternized in advance, or may be quaternized after polymerization. Examples of the quaternizing agent include alkyl halides such as methyl chloride and methyl iodide, diethyl sulfate, and di-n-propyl sulfate.

The monomer represented by the formula (II) is preferably styrene in which R ⁴ is a hydrogen atom, and the monomer represented by the formula (III) is preferably a hydrogen atom, R ^{5 6} is preferably an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of the monomer represented by the formula (III) include butyl acrylate and 2-ethylhexyl acrylate. The monomer represented by the formula (IV) is preferably a monomer in which R ⁷ is a methyl group, and R ⁸ and R ⁹ are a methyl group or an ethyl group, more preferably R ⁷ , R ⁸ and R ^9. Each is preferably dimethylaminoethyl methacrylate where is a methyl group.

  In the quaternary ammonium base-containing styrenic resin, the content of the monomer represented by the formula (II) in the monomer mixture is preferably 60 to 97% by weight, more preferably 70 to 90% by weight. The content of the monomer represented by the formula (III) is preferably 1 to 33% by weight, more preferably 5 to 20% by weight, and the monomer represented by the formula (IV) or its 4 The content of the graded product is preferably 2 to 35% by weight, more preferably 5 to 20% by weight.

  Specific examples of quaternary ammonium base-containing styrenic resins obtained using monomers represented by formulas (II) to (IV) include butyl acrylate, N, N-diethyl-N-methyl-2- And (methacryloyloxy) ethylammonium / styrene copolymer.

  Polymerization of a monomer mixture of a quaternary ammonium base-containing styrenic resin is performed by, for example, heating the monomer mixture to 50 to 100 ° C. in an inert gas atmosphere in the presence of a polymerization initiator such as azobisdimethylvaleronitrile. This can be done. The polymerization method may be any of solution polymerization, suspension polymerization or bulk polymerization, but is preferably solution polymerization.

  The softening point of the quaternary ammonium base-containing resin is preferably from 100 to 140 ° C, more preferably from 115 to 130 ° C, from the viewpoint of low-temperature fixability and positive chargeability of the toner.

  The amount of the positively chargeable charge control resin used is preferably 3 to 40 parts by weight, preferably 4 to 30 parts by weight, and 5 to 20 parts per 100 parts by weight of the binder resin from the viewpoint of developing positive chargeability of the toner. Part by weight is more preferred.

  The positively chargeable charge control agent is preferably a nitrogen-containing compound, such as “Bontron N-01”, “Bontron N-04”, “Bontron N-07” (manufactured by Orient Chemical Industries), “CHUO CCA- 3 ”(manufactured by Chuo Gosei Co., Ltd.), etc .; triphenylmethane dyes containing tertiary amines as side chains; for example,“ Bontron P-51 ”(manufactured by Orient Chemical Industries),“ TP-415 ”(preservation) Quaternary ammonium salt compounds such as “Tsuchiya Chemical Industry Co., Ltd.”, cetyltrimethylammonium bromide, “COPYCHARGEPXVP435” (Hoechst); for example, “PLZ-2001”, “PLZ-8001” (above, Shikoku Kasei Co., Ltd.) Examples thereof include imidazole derivatives.

  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.

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

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used, and the toner of the present invention may be either a black toner or a 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.

  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 and more preferably 0.8 to 5 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of dispersibility in the binder resin.

  The toner of the present invention may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsion phase inversion method, or a polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, A pulverized toner obtained by a melt kneading method is preferred. In the case of pulverized toner by the melt-kneading method, for example, a raw material such as a binder resin, a colorant, and a charge control agent is uniformly mixed with a mixer such as a Henschel mixer, and then a hermetically sealed kneader, a single or twin screw extruder It can be produced by melt-kneading with an open roll 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 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.

  In the toner of the present invention, it is preferable to use inorganic fine particles as an external additive in order to improve transferability. Specifically, at least one selected from the group consisting of silica, alumina, titania, zirconia, tin oxide, and zinc oxide is preferable. Among these, silica is preferable, and from the viewpoint of preventing embedding, the specific gravity is More preferably, small silica is contained.

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

  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 electrophotographic 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 (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 Example 1 [Resin A]
The 2,6-pyridinedicarboxylic acid and alcohol component shown in Table 1 and the esterification catalyst were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless steel stirring bar, a flow-down condenser and a nitrogen inlet tube, and nitrogen was added. The reaction was carried out in a mantle heater in an atmosphere at 200 ° C. and normal pressure (101.3 kPa) until the reaction rate reached 90%, and further reacted at 8 kPa for 1 hour. The mixture was cooled to 150 ° C., charged with terephthalic acid shown in Table 1, reacted at 230 ° C. and normal pressure until the reaction rate reached 90%, and further reacted at 8 kPa for 1 hour. After cooling to 210 ° C., trimellitic anhydride shown in Table 1 was added and reacted at normal pressure for 1 hour, and then reacted to a desired softening point at 8 kPa to obtain a polyester (resin A).

Resin production example 2 [resins B, C, F]
Put the carboxylic acid component, alcohol component, and esterification catalyst except trimellitic anhydride shown in Table 1 into a 5 liter four-necked flask equipped with a thermometer, stainless steel stir bar, flow-down condenser and nitrogen inlet tube. The reaction was continued in a mantle heater in a nitrogen atmosphere at 200 ° C. and normal pressure (101.3 kPa) until the reaction rate reached 90%, and further reacted at 8 kPa for 1 hour. Trimellitic anhydride shown in Table 1 was added, reacted at 210 ° C. for 1 hour at normal pressure, and then reacted at 8 kPa to the desired softening point to obtain polyesters (resins B, C, and F).

Resin Production Example 3 [Resin D]
The 2,6-pyridinedicarboxylic acid and alcohol component shown in Table 1 and the esterification catalyst were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless steel stirring bar, a flow-down condenser and a nitrogen inlet tube, and nitrogen was added. The reaction was carried out in a mantle heater in an atmosphere at 200 ° C. and normal pressure (101.3 kPa) until the reaction rate reached 90%, and further reacted at 8 kPa for 1 hour. After cooling to 180 ° C., fumaric acid and a polymerization inhibitor (t-butylcatechol) shown in Table 1 were added, the temperature was raised to 210 ° C. over 4 hours, and the reaction was carried out at 210 ° C. for 1 hour at normal pressure. Thereafter, the reaction was carried out to a desired softening point at 8 kPa to obtain polyester (resin D).

Resin Production Example 4 [Resin E]
A 5-liter four-necked flask equipped with a 2,6-pyridinedicarboxylic acid, an alcohol component, and an esterification catalyst shown in Table 1 equipped with a thermometer, a stainless steel stirring rod, a falling condenser, a rectification column, and a nitrogen introduction tube The mixture was heated to 180 ° C. in a mantle heater in a nitrogen atmosphere and heated to 200 ° C. over 5 hours. The reaction was continued at 200 ° C. and normal pressure (101.3 kPa) until the reaction rate reached 90%, and then further reacted at 40 kPa for 1 hour. Trimellitic anhydride shown in Table 1 was added and reacted at 210 ° C. for 1 hour at normal pressure, and then reacted to a desired softening point at 40 kPa to obtain polyester (resin E).

Resin Production Example 5 [Resin G, H]
Put the carboxylic acid component, alcohol component, and esterification catalyst except trimellitic anhydride shown in Table 1 into a 5 liter four-necked flask equipped with a thermometer, stainless steel stir bar, flow-down condenser and nitrogen inlet tube. The reaction was continued in a mantle heater in a nitrogen atmosphere at 230 ° C. and normal pressure (101.3 kPa) until the reaction rate reached 90%, and further reacted at 8 kPa for 1 hour. Trimellitic anhydride shown in Table 1 was added and reacted at 210 ° C. for 1 hour at normal pressure, and then reacted at 8 kPa to the desired softening point to obtain polyesters (resins G and H).

Examples 1-8 and Comparative Example 1
100 parts by weight of binder resin shown in Table 2, 4 parts by weight of carbon black “MOGUL L” (Cabot), positively chargeable charge control resin “FCA-701PT” (Fujikura Kasei Co., Ltd., quaternary ammonium base-containing styrene acrylic) 10 parts by weight of a copolymer, softening point: 123 ° C.) and 1 part by weight of polypropylene wax “NP-105” (Mitsui Chemicals, melting point: 140 ° C.) are thoroughly mixed with a Henschel mixer, and then rotated in the same direction by twin screw extrusion. This was melt kneaded at a roll rotation speed of 200 r / min and a heating temperature of 80 ° C. in the roll. 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 7.5 μm.

  To 100 parts by weight of the obtained toner particles, 1.0 part by weight of hydrophobic silica “Aerosil R-972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added and mixed with a Henschel mixer to obtain each toner.

Example 9
100 parts by weight of binder resin shown in Table 2, 6 parts by weight of cyan pigment “Toner Cyan BG” (Clariant, CI Pigment Blue 15: 3), positively chargeable charge control resin “FCA-201PS” (manufactured by Fujikura Kasei) , Quaternary ammonium base-containing styrene-acrylic copolymer, softening point: 111 ° C.) and 10 parts by weight of mold release agent “HNP-9” (manufactured by Nippon Seiki Co., Ltd., melting point: 75 ° C.) using a Henschel mixer After thorough mixing, melt kneading was performed at a roll rotation speed of 200 r / min and a heating temperature in the roll of 80 ° C. using a co-rotating twin screw extruder. 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 7.5 μm.

  Cyan toner is obtained by adding 1.0 part by weight of hydrophobic silica `` Aerosil R-972 '' (manufactured by Nippon Aerosil Co., Ltd.) as an external additive to 100 parts by weight of the obtained toner particles and mixing with a Henschel mixer. It was.

Test Example 1 [low temperature fixability]
Toner was mounted on an apparatus obtained by modifying a non-magnetic one-component developing type printer “HL-2040” (manufactured by Brother Industries) to obtain an unfixed image. 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 160 ° C.
B: The minimum fixing temperature is 160 ° C. or higher and lower than 180 ° C.
C: The minimum fixing temperature is 180 ° C. or higher.

Test Example 2 [Preservation]
4 g of toner was left for 48 hours in an environment of a temperature of 50 ° C. and a humidity of 60%. 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 recognized at all.
B: Slight aggregation is observed.
C: Aggregation is clearly observed.

Test Example 3 [Chargeability]
Toner was mounted on Brother Industries' printer “HL-2040” and 10000 images with a printing rate of 5% were printed continuously. At that time, a solid image was printed every 1000 sheets printed, the obtained image was visually observed, and solid followability was evaluated as chargeability according to the following evaluation criteria. The results are shown in Table 2. The greater the number of sheets until the image density is lowered, the better the solid followability.

〔Evaluation criteria〕
A: Up to 10,000 sheets, there was no decrease in image density.
B: A decrease in image density was observed between 5,000 and less than 10,000.
C: A decrease in image density was observed at less than 5000 sheets.

  From the above results, it can be seen that the toners of Examples 1 to 9 are excellent in all of low-temperature fixability, storage stability, and chargeability as compared with the toner of Comparative Example 1.

  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 (5)

  An electron comprising a binder resin containing a polyester obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing a carboxylic acid compound having a pyridine skeleton in the molecule, and a positively chargeable charge control resin. Toner for photography.   The toner for electrophotography according to claim 1, wherein the carboxylic acid compound having a pyridine skeleton in the molecule is a dicarboxylic acid compound.   The electrophotographic toner according to claim 1, wherein the content of the carboxylic acid compound having a pyridine skeleton in the molecule is 20 mol% or more in the carboxylic acid component.   The carboxylic acid component further contains a trivalent or higher aromatic carboxylic acid compound, and the molar ratio between the trivalent or higher aromatic carboxylic acid compound and the carboxylic acid compound having a pyridine skeleton in the molecule (a trivalent or higher aromatic The electrophotographic toner according to claim 1, wherein the group carboxylic acid compound / carboxylic acid compound having a pyridine skeleton in the molecule is 1/10 to 1/1.   The toner for electrophotography according to any one of claims 1 to 4, wherein the acid value of the polyester is less than 15 mgKOH / g.