JP2010008579A - Positive chargeable toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive chargeable toner with good chargeability as a positive chargeable toner and excellent in preventing fogging and in follow-up property of a solid image even when the toner contains a polyester as a binder resin. <P>SOLUTION: The positive chargeable toner includes a binder resin and a charge control resin, wherein the binder resin contains a polyester H with a storage modulus of ≥5.0×10<SP>3</SP>Pa at 130°C and a polyester L with a storage modulus of ≥1.0×10<SP>3</SP>Pa and less than 5.0×10<SP>3</SP>Pa at 130°C, with the difference in the storage modulus of ≥1.0×10<SP>3</SP>Pa from that of the polyester H; and the charge control resin includes a styrene-acryl copolymer with a storage modulus ranging from 1.0×10<SP>3</SP>to 4.0×10<SP>3</SP>Pa at 130°C, with the content of the styrene-acrylic copolymer ranging 5-40 pts.wt. with respect to 100 pts.wt. of the polyester L. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  As a binder resin for toner, polyester is excellent in fixability and durability. However, since it has a strong negative chargeability compared to styrene acrylic resin etc., the chargeability is improved when used as a binder resin for positively chargeable toners. is necessary. Thus, as means for improving the positive chargeability of the polyester, a method of lowering the acid value of the polyester and a technique of adding a charge control resin (CCR) having a good positive chargeability as a charge control agent are known.

For example, in Patent Document 1, in a toner mainly composed of a binder resin, a colorant, and a charge control agent, the charge control agent is a resin having a chargeable functional group, and the binder resin and the charge control agent are 150 ° C. Discloses an electrostatic charge image developing toner characterized by having a specific relationship with storage elastic modulus G ′. This is because when the compatibility between the binder resin and the charge control resin is inferior, the charge control resin is dispersed in a sea-island structure, whereas there is a certain difference in the storage elastic modulus at the time of melting and kneading the two, the binder resin side When the elasticity of the resin is high, it is estimated that a strong kneading share acts on the island structure of the charge control resin and the charge control resin is more uniformly dispersed. Further, there is disclosed a toner having a sufficient charge amount, a sharp charge amount distribution, and less fogging during continuous copying when the difference in loss elastic modulus between the binder resin and the charge control resin is small. This is presumed to be because when there is a difference in viscosity between the binder resin and the charge control agent at the time of melt-kneading, the uniform dispersibility of the two is inhibited.
JP-A-11-305489

  However, in the invention described in Patent Document 1, the dispersibility of the charge control resin is insufficient only by providing a certain difference between the storage elastic modulus of the binder resin and the storage elastic modulus of the charge control resin. It may be difficult to achieve both good solid followability. In addition, from the viewpoint of performance such as fixability and hot offset resistance, the binder resin is designed by combining two or more kinds of resins having different storage elastic modulus instead of adjusting the storage elastic modulus of the entire binder resin. May be desirable.

  An object of the present invention is to provide a positively chargeable toner that has good chargeability as a positively chargeable toner and has excellent prevention of fogging and solid followability even if it contains polyester as a binder resin. is there.

The present invention is a positively chargeable toner comprising a binder resin and a charge control resin, the binder resin comprising a polyester H having a storage elastic modulus at 130 ° C. of 5.0 × 10 ³ Pa or more and 130 ° C. And the polyester L having a storage elastic modulus of 1.0 × 10 ³ Pa or more and less than 5.0 × 10 ³ Pa and a difference in storage elastic modulus from the polyester H of 1.0 × 10 ³ Pa or more. Is a styrene acrylic copolymer having a storage elastic modulus at 130 ° C. of 1.0 × 10 ^{3 to} 4.0 × 10 ³ Pa, and the content of the styrene acrylic copolymer is 100 parts by weight of polyester L The present invention relates to a positively chargeable toner that is 5 to 40 parts by weight.

  The positively chargeable toner of the present invention has excellent chargeability even if it contains polyester as a binder resin, and exhibits the effect of preventing fogging and being excellent in solid followability.

  The positively chargeable toner of the present invention comprises a binder resin having a specific storage elastic modulus and a charge control resin, that is, two kinds of polyesters having a specific storage elastic modulus as the binder resin, and a specific storage elasticity as the charge control resin. It has the big characteristic in the point which contains the styrene acrylic copolymer which has a rate. The styrene acrylic copolymer has good positive chargeability as a charge control resin, but has low dispersibility with respect to polyester. However, by combining with a polyester having a storage modulus close to that of a styrene-acrylic copolymer, a uniform share can be imparted when the toner raw material is melt-kneaded. It is estimated that it can be improved. Thereby, it is presumed that a decrease in chargeability can be suppressed, and the occurrence of fogging and the decrease in solid followability due to the decrease can be prevented.

The storage elastic modulus at 130 ° C. of the styrene acrylic copolymer is 1.0 × 10 ^{3 to} 4.0 × 10 ³ Pa, preferably 1.2 × 10 ^{3 to} 3.5 from the viewpoint of dispersibility of the charge control resin in the binder resin. × 10 ³ Pa, more preferably 1.4 × 10 ^{3 to} 3.0 × 10 ³ Pa. On the other hand, the storage elastic modulus of the polyester L contained as a polyester having a storage modulus close to the storage elastic modulus at 130 ° C. is 1.0 × 10 ³ Pa or more and less than 5.0 × 10 ³ Pa, preferably 1.0 × 10 ^{3 to} 4.0 × 10 ³ Pa, more preferably 1.2 × 10 ^{3 to} 3.5 × 10 ³ Pa, and still more preferably 1.5 × 10 ^{3 to} 3.0 × 10 ³ Pa. Furthermore, from the viewpoint of improving the dispersibility of the charge control resin by giving a kneading share when kneading the binder resin and the charge control resin, the toner of the present invention has at least a storage elastic modulus at 130 ° C. as the binder resin. However, the polyester H contains 5.0 × 10 ³ Pa or more, preferably 5.5 × 10 ^{3 to} 8.0 × 10 ³ Pa, more preferably 6.0 × 10 ^{3 to} 7.0 × 10 ³ Pa. The difference in storage elastic modulus between polyester L and polyester H is 1.0 × 10 ³ Pa or more, preferably 1.0 × 10 ^{3 to} 9.0 × 10 ³ Pa, more preferably 2.0 × 10 ^{3 to} 9.0 × 10 ³ Pa, It is preferably 3.0 × 10 ^{3 to} 6.0 × 10 ³ Pa.

  The ratio of storage elastic modulus of polyester L at 130 ° C. and storage elastic modulus of styrene acrylic copolymer at 130 ° C. (storage elastic modulus of styrene acrylic copolymer / storage elastic modulus of polyester L) is: From the viewpoint of dispersibility of the styrene acrylic copolymer in the binder resin, 0.5 to 3 is preferable, 0.5 to 2 is more preferable, and 0.6 to 0.9 is more preferable. The storage elastic modulus of the polyester and styrene-acrylic copolymer can be adjusted by changing the molecular weight and molecular weight distribution depending on the raw material monomer (monomer), the reaction time of polyesterification, and the like. For example, if the amount of a crosslinkable monomer used as a raw material monomer (monomer) is increased, the storage elastic modulus tends to increase, and if the polyesterification reaction time is lengthened, the storage elastic modulus tends to increase. Since the temperature of the binder resin and the charge control resin is estimated to be around 130 ° C. during the kneading of the binder resin and the charge control resin, the storage modulus in the present invention focuses on the measured value at 130 ° C. ing.

  In the positively chargeable toner of the present invention, the polyester contained as the binder resin is not particularly limited, but is a raw material containing an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound. Obtained by condensation polymerization of monomers.

  As the dihydric or higher alcohol, from the viewpoint of the storage stability of the toner, the formula (I):

(In the formula, 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, and each is a positive number; The average value of the sum of y and y is preferably 1 to 16, more preferably 1 to 8, and even more preferably 1.5 to 4)
An alkylene oxide adduct of bisphenol A represented by The content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 60 mol% or more, and further preferably 80 mol% or more in the alcohol component.

The alkylene oxide adduct of bisphenol A represented by the formula (I), polyoxyethylene-2,2-bis (4-hydroxyphenyl) ethylene oxide adduct R ¹ is 2 carbon atoms such as propane, polyoxy Examples thereof include propylene oxide adducts having R ¹ of 3 carbon atoms such as propylene-2,2-bis (4-hydroxyphenyl) propane.

  As alcohol components other than the alkylene oxide adduct of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, sorbitol , Pentaerythritol, glycerol, trimethylolpropane and the like.

  Examples of the divalent or higher carboxylic acid compound include adipic acid, fumaric acid, maleic acid, succinic acid (for example, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isooctenyl succinic acid, Aliphatic carboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms such as isooctyl succinic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,2, 4-Benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, aromatic carboxylic acids such as pyromellitic acid, anhydrides of these acids and lower alkyl (C1-3) esters, etc. Is mentioned. In addition, the acids as described above, anhydrides of these acids, and alkyl esters of the acids are collectively referred to as carboxylic acid compounds in this specification.

  The polyester is preferably a crosslinked polyester obtained using a trivalent or higher monomer as the alcohol component and / or carboxylic acid component from the viewpoint of the softening point and grindability. The content of the trivalent or higher monomer is preferably 2 to 50 mol%, more preferably 10 to 30 mol%, based on the total amount of the alcohol component and the carboxylic acid component. As the trivalent or higher monomer, 1,2,4-benzenetricarboxylic acid (trimellitic acid) and its anhydride are 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 viewpoint of adjusting the molecular weight and improving the offset resistance of the toner.

  The polycondensation of the alcohol component and the carboxylic acid component can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C. From the viewpoint of promoting the progress of the reaction, in the presence of an esterification catalyst. It is preferable to carry out with. Examples of esterification catalysts include dibutyltin oxide, titanium compounds, tin (II) compounds having no Sn—C bond, and the like. These may be used alone or in combination. Of these, tin catalysts such as dibutyltin oxide and tin (II) compounds having no Sn—C bond are preferred from the viewpoint of chargeability, and tin (II) compounds having no Sn—C bond are preferred. Is more preferable.

  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 preferred, tin (II) octoate, tin (II) 2-ethylhexanoate, tin (II) stearate and tin (II) oxide are more preferred, tin (II) octoate and 2-ethylhexane Even more preferred is tin (II) acid.

  The amount of the esterification catalyst is preferably about 0.1 to 0.7 parts by weight with respect to 100 parts by weight of the polyester raw material monomer.

  In the present invention, the polyester may be a polyester modified to such an extent that the characteristics are not substantially impaired. 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.

  In the present invention, the softening point of the polyester H is preferably 150 to 170 ° C., more preferably 150 to 160 ° C., from the viewpoint of hot offset resistance of the toner. On the other hand, the softening point of polyester L is preferably 90 to 130 ° C, more preferably 100 to 125 ° C, from the viewpoint of low-temperature fixability. Further, the difference between the softening points of the polyester H and the polyester L is preferably 20 to 60 ° C., more preferably 20 to 40 ° C., from the viewpoints of toner fixability and offset resistance. In addition, when it consists of three or more types of resins, it is preferable that two types satisfying the above from the one with the largest content. For example, when the second and third in the descending order are the same content, Preferably, the second one satisfies the above. The softening point of the polyester can be adjusted by the raw material monomer, the reaction time for polyesterification, and the like.

  The content of polyester L in the binder resin is preferably 20 to 80% by weight, more preferably 30 to 80% by weight, and 40 to 70% by weight from the viewpoint of dispersibility of the styrene acrylic copolymer in the toner. Is more preferable. The weight ratio of polyester H to polyester L (polyester H / polyester L) is preferably 20/80 to 80/20, more preferably 20/80 to 70/30, and more preferably 30/70 to 60/40.

  The average softening point of polyester H and polyester L is preferably 120 to 160 ° C, more preferably 130 to 155 ° C. In this specification, an average softening point means a weighted average softening point, and each softening point is measured by the method as described in the below-mentioned Example.

  The glass transition point of the polyesters H and L is preferably 50 to 85 ° C, and more preferably 55 to 80 ° C. In addition, the acid value of polyesters H and L is preferably 10 mgKOH / g or less, more preferably 6 mgKOH / g or less, from the viewpoint of improving positive chargeability. In this specification, a glass transition point and an acid value are measured by the method as described in the below-mentioned Example.

  Further, the toner of the present invention may contain a binder resin other than the polyesters L and H as long as the effects of the present invention are not impaired. The polyester may be contained as a polyester-based resin such as polyester-polyamide, a composite resin having two or more resin components. Here, the composite resin refers to a resin in which a condensation polymerization resin such as polyester, polyester / polyamide and the like and an addition polymerization resin such as vinyl polymerization resin are partially chemically bonded. Even if it is obtained as a raw material, or obtained from a raw material monomer of one type of resin and another type of resin, it is obtained from a mixture of raw material monomers of two or more types of resin. However, in order to obtain a composite resin efficiently, those obtained from a mixture of raw material monomers of two or more resins are preferable. Examples of the binder resin other than the polyester resin include known resins used for toner, such as styrene-acrylic resin, epoxy resin, polycarbonate, and polyurethane. The total content of polyesters H and L is not particularly limited, but is preferably 90% by weight or more, and more preferably 100% by weight in the binder resin from the viewpoint of low-temperature fixability.

  In the present invention, the styrene-acrylic copolymer contained as the charge control resin is preferably a quaternary ammonium base-containing styrene-acrylic copolymer from the viewpoint of developing positive chargeability of the toner, and is represented by 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 ⁶ 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)
Or a quaternized product thereof, preferably a quaternary ammonium base-containing styrene acrylic system obtained by a step including a polymerization step of a monomer mixture containing a monomer represented by formula (IV) A copolymer is more preferred.

The monomer represented by formula (II) is preferably styrene in which R ⁴ is a hydrogen atom, and the monomer represented by formula (III) is preferably R ⁵ is a hydrogen atom and R ⁶ is A monomer having an alkyl group having 1 to 4 carbon atoms, more preferably butyl acrylate in which R ⁵ is a hydrogen atom and R ⁶ is a butyl group, and a 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 dimethylaminoethyl methacrylate in which R ⁷ , R ⁸ and R ⁹ are methyl groups, respectively, is desirable.

  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 is preferably 1 to 33% by weight, more preferably 5 to 20% by weight, and the content of the monomer represented by the formula (IV) or a quaternized product thereof is preferably 2%. It is desirable to be -35 wt%, more preferably 5-20 wt%.

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

  The softening point of the styrene acrylic copolymer is preferably 115 ° C. or higher, more preferably 115 to 140 ° C., further preferably 117 to 140 ° C., and still more preferably 120 to 135 ° C. from the viewpoint of hot offset resistance. Further, the softening point of the styrene-acrylic copolymer is preferably within 15 ° C., more preferably within 10 ° C., with respect to the softening point of the polyester L.

  The content of the styrene acrylic copolymer is from 5 to 40 parts by weight, preferably from 5 to 30 parts by weight, more preferably from 5 parts by weight, based on 100 parts by weight of the polyester L, from the viewpoint of positive charging of the toner. ~ 20 parts by weight.

  Furthermore, the toner of the present invention may contain a charge control agent other than the styrene acrylic copolymer as long as the effects of the present invention are not impaired. Examples of the other charge control agent include known charge control agents, but the content of the styrene acrylic copolymer in the charge control agent is preferably 70% by weight or more, more preferably 80% by weight or more, and 90% More preferably, it is more preferably 100% by weight or more.

  In the present invention, in addition to the binder resin and the charge control resin, a colorant, a release agent, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a magnetic substance, etc. These additives may be blended as a toner raw material.

  Examples of the colorant used in the toner of the present invention include carbon black; inorganic pigments such as iron black; acetoacetic acid arylamide monoazo yellow pigments such as CI Pigment Yellow 1, 3, 74, 97, and 98; CI Pigment Yellow 12, 13, 14, 17 etc. Acetoacetate Arylamide Disazo Yellow Pigment; CI Solvent Yellow 19, 77, 79, CI Disperse Yellow 164 etc. Yellow Dye; CI Pigment -Red 48, 49: 1, 53: 1, 57, 57: 1, 81, 122, 5 etc. Red or red pigment; CI Solvent Red 49, 52, 58, 58 Red dyes such as 8; CI pigment blue 15: 3 copper phthalocyanine and its derivatives blue dyes and pigments; CI pigment green 7 and 36 (phthalocyanine green) and other green pigments can be used . These dyes and pigments may be used alone or in combination of two or more. The content of the colorant is preferably about 1 to 15 parts by weight with respect to 100 parts by weight of the binder resin.

  The mold release agent preferably contains a wax having a melting point of preferably 140 ° C. or higher, more preferably 145 to 160 ° C. from the viewpoint of hot offset resistance.

  As the wax, a hydrocarbon wax is preferable from the viewpoint of toner fixability and hot offset resistance. Examples of the hydrocarbon wax include polyolefin wax, paraffin wax, petroleum wax, hydrocarbon wax obtained by the Fischer-Tropsch method, and derivatives and modified products thereof.

  Examples of the polyolefin wax include polyethylene wax and polypropylene wax. In the present specification, the melting point of the wax is measured by the method described in Examples below.

  As the paraffin wax, either one using coal as a raw material or one using petroleum as a raw material can be used, but paraffin wax obtained by refining petroleum is preferable from the viewpoint of improving durability. In addition, high-purity refined paraffin wax in which the petroleum wax extracted from petroleum is further separated and purified by distillation under reduced pressure to increase the proportion of linear hydrocarbons can be used.

  Among the hydrocarbon waxes, polyolefin waxes are preferable from the viewpoint of durability.

  The wax content is preferably 0.1 to 5.0 parts by weight and more preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner of the present invention is preferably a pulverized toner obtained by a kneading and pulverizing method in which the effects of the present invention are more remarkably exhibited. For example, in the case of pulverized toner by a kneading pulverization method, toner materials such as a binder resin, a charge control resin, a colorant, and a release agent are uniformly mixed with a mixer such as a Henschel mixer, and then a sealed kneader or a single screw or It can be manufactured by melt-kneading with a twin-screw extruder, open roll type kneader or the like, cooling, pulverizing and classifying.

  The toner of the present invention may be further externally treated with an external additive such as inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide and zinc oxide, and organic fine particles such as resin fine particles.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably from 3 to 15 μm, more preferably from 4 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 positively chargeable toner of the present invention can be used as it is as a one-component developing toner or as a two-component developer by mixing with a carrier.

[Storage elastic modulus of resin and styrene acrylic copolymer (G ')]
Measurement is performed using a viscoelasticity measuring device (rheometer) RDA-III (manufactured by Rheometrics).
Measurement jig: A parallel plate with a diameter of 25 mm is used.
Measurement sample: Toner is pressurized, and a cylindrical sample having a diameter of about 8 mm and a height of 2 to 5 mm and a disk-shaped sample having a diameter of about 25 mm and a thickness of 2 to 3 mm are used.
The measurement equipment conditions are set as follows.

Geometry: Parallel Plate (25mm)
Radius: 12.5 (mm)
Gap: Gap at 80 ℃
Once the sample is stuck to the plate at 120 ° C, the temperature is lowered to 80 ° C.
Enter the gap where Axal Force is 0.
1.Dynamic Mechanical Analysis
Frequency / Temperature Sweep
2.Test Parameters
Strain: 0.1 (%)
Initial Temperature ： 80 (℃)
3.Sweep Paramerters
Sweep Type: Discrete
Final temperature: 120 (℃)
Step Size: 1 (℃)
Soak Time: 30 (s)
First Frequency: 1.0 (rad / s)
Second Frequency: 6.28 (rad / s)
Third Frequency: 100 (rad / s)
Fourth Frequency: 250 (rad / s)
Fifth Frequency: 500 (rad / s)
4.Options
Delay Before Test: 30 (s)
Correlation Delay: 0.0 (Cycles)
1Cycle Correlation: No
Auto tension: Yes

[Softening point of resin and styrene acrylic copolymer]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample is heated at a heating rate of 6 ° C / min. While applying a load of 1.96 MPa with a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . Plot the plunger drop amount of the flow tester against the temperature, and let the softening point be the temperature at which half of the sample flows out.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C at a rate of 10 ° C / min and cooled to 0 ° C at a rate of 10 ° C / min. Start measurement at / min. The glass transition point is defined as the temperature at the intersection of the base line extension below the glass transition point and the tangent that indicates the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
Measured by 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 wax]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C and then cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. Determine the maximum peak temperature of heat of fusion.

[Volume-median particle size of toner (D ₅₀ )]
In this specification, the volume-median particle size (D ₅₀ ) of the toner means the particle size of the toner in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.
Measuring instrument: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% by weight Electrolyte dispersion condition: 10 mg of measurement sample was added to 5 mL of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Thereafter, 25 mL of an electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: The dispersion is added to 100 mL of the electrolytic solution so that the particle size of 30,000 toner particles can be measured in 20 seconds, and 30,000 particles are measured. Determine the median particle size (D ₅₀ ).

Example of resin production The alcohol component and carboxylic acid component shown in Table 1 and 20 g of tin (II) 2-ethylhexanoate as an esterification catalyst were added in a 5-liter volume equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple. After putting into a four-necked flask and reacting at 230 ° C. in a nitrogen atmosphere until the reaction rate reaches 90%, the reaction is carried out at 8.3 kPa until the desired softening point is reached. Resins H-1, L-1 L-2 and a were obtained. The reaction rate means a value of the amount of generated reaction water (mol) / theoretical generated water amount (mol) × 100.

Examples 1-7 and Comparative Examples 1-5
100 parts by weight of binder resin and charge control resin shown in Table 2, 4.0 parts by weight of colorant “Regal 330R” (manufactured by Cabot), and polypropylene wax “NP-055” (manufactured by Mitsui Chemicals, melting point: 145 ° C.) 2.0 The parts by weight were mixed using a Henschel mixer. The obtained mixture was melt-kneaded by a twin screw extruder, cooled, and then roughly pulverized to about 1 mm using a hammer mill. The obtained coarsely pulverized product was finely pulverized by an air jet pulverizer and classified to obtain toner particles having a volume median particle size (D ₅₀ ) of 7.5 μm.

  To 100 parts by weight of toner particles, 0.5 parts by weight of hydrophobic silica “NAX-50” (manufactured by Nippon Aerosil Co., Ltd.) and 0.5 parts by weight of hydrophobic silica “RX-300” (manufactured by Nippon Aerosil Co., Ltd.) are added, and a Henschel mixer is used. And externally added to obtain a toner.

Test Example 1 [Fog]
A printer for positively charged toner “HL-2040” manufactured by Brother Industries, Ltd. was filled with toner, printed with a solid white image, and the power was turned off halfway. When the power is turned off, the toner on the surface of the photoconductor is attached to the mending tape, and the color density is measured with the image density measuring device “SPM-50” (Gretag), and the tape before the toner is attached is measured. The difference from the color density was determined. This density difference was taken as the first color density. Then, after printing 5,000 images with a printing rate of 1% under the condition of intermittent printing for 20 seconds per page, a white solid image is printed, and the power is turned off halfway and the toner on the surface of the photoconductor is attached to the mending tape. The color density was measured with a density measuring device “SPM-50” (manufactured by Gretag), and the difference from the color density of the tape before the toner was deposited was determined. This density difference was taken as the 5000th color density. The fog was evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for fogging]
The difference in color density between the first and the 5000th sheet is A: less than 0.08 B: 0.08 or more, less than 0.13 C: 0.13 or more, less than 0.15 D: 0.15 or more

Test example 2 [solid followability]
Brother HL-2040, a positively charged toner printer manufactured by Brother Industries, was filled with toner, and 10,000 pages of images with a printing rate of 1% were printed on a page with 20 seconds intermittent. At that time, a solid image was printed every 1000 sheets printed, the obtained image was visually observed, and solid followability was evaluated according to the following evaluation criteria. The results are shown in Table 2.

[Evaluation criteria for solid followability]
A: Even after printing 10,000 sheets, the image density does not decrease and the solid followability is good. B: The image density decline is observed when printing from 8000 to less than 10,000 sheets, and the solid followability decreases. C: From 5000 to less than 8000 sheets Image density reduction is observed in printing, and solid followability is reduced. D: Image density reduction is observed in printing less than 5000 sheets, and solid followability is reduced.

  From the above results, the toners of Examples 1 to 7 have good chargeability as positively chargeable toners as compared with the toners of Comparative Examples 1 to 5, and also have good fog prevention and solid followability. I understand that.

  The positively chargeable toner of the present invention is suitably used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims (5)

A positively chargeable toner comprising a binder resin and a charge control resin, wherein the binder resin comprises polyester H having a storage elastic modulus of 5.0 × 10 ³ Pa or more at 130 ° C. and storage elasticity at 130 ° C. The charge control resin contains a polyester L having a modulus of 1.0 × 10 ³ Pa or more and less than 5.0 × 10 ³ Pa and a difference in storage elastic modulus from the polyester H of 1.0 × 10 ³ Pa or more. The styrene-acrylic copolymer having a storage elastic modulus of 1.0 × 10 ^{3 to} 4.0 × 10 ³ Pa at 5 to 40% by weight based on 100 parts by weight of the polyester L A positively chargeable toner.   Ratio of storage elastic modulus of polyester L at 130 ° C. and storage elastic modulus of styrene acrylic copolymer at 130 ° C. (storage elastic modulus of styrene acrylic copolymer / storage elastic modulus of polyester L) is 0.5-3. The positively chargeable toner according to claim 1, wherein   The positively chargeable toner according to claim 1 or 2, wherein the styrene acrylic copolymer is a quaternary ammonium base-containing styrene acrylic copolymer.   The positively chargeable toner according to claim 1, wherein the binder resin contains 20 to 80% by weight or more of polyester L.   The positively chargeable toner according to claim 1, which is a pulverized toner obtained by a kneading pulverization method.