JP2000010347A - Electrostatic charge image developing toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner with excellent charging characteristic capable of providing an image of high quality even in the repeated use over a long period by specifying the surface density of a quaternary ammonium salt. SOLUTION: This toner consists of at least a binder resin, a coloring agent, a quaternary ammonium salt, and a polyolefin wax, and the surface density of the quaternary ammonium salt is 0.10-0.40. When the surface density is above this range, the charging quantity of toner is reduced to cause toner scattering that the floating toner contaminates a developing machine in the repeated use of the toner. When the surface density is below this range, charging stability cannot be provided, and a stable quality of image cannot be kept in the repeated use of the toner. To set the surface density within the above range, the binder resin, the coloring agent and the quaternary ammonium salt are mixed to form a mixture, and the mixing condition or kneading condition in fusing and kneading of this mixture is properly regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner for developing electrostatic images. More specifically, the present invention relates to a toner for developing electrostatic images having excellent charging characteristics and a long life, which can provide a high-quality image even when repeatedly used for a long period of time.
The present invention also relates to a method for producing a toner for developing an electrostatic image having such characteristics.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat. No. 2,297,691.
No., JP-B-42-23910 and JP-B-43-2
As variously disclosed in, for example, Japanese Patent No. 4748, an electric latent image of an electrostatic charge is generally formed on a photoreceptor containing a photoconductive substance by various means, and then the latent image is formed with a pre-charged toner. After developing as a powder image and transferring this powder image to paper or the like as necessary, it is fixed by heating, pressing or solvent vapor. At this time, as a developer for developing an electrostatic latent image formed on the photoreceptor, a carrier that carries the toner by electrostatic force on the surface of the toner and transports itself to the vicinity of the photoreceptor by magnetic force Particle size 3 called
A two-component developer composed of iron powder, ferrite, magnetite or the like having a size of about 0 to 200 μm, and a one-component developer composed of only a toner without requiring a carrier are known. An ordinary toner is obtained by dispersing a colorant, a charge control agent and the like in a binder resin such as a styrene-acrylic copolymer or a copolymer of terephthalic acid and bisphenol A.
Nigrosine-based dye, which is conventionally finely pulverized to about 30 μm, and has conventionally been used to impart positive chargeability to the toner.
Triphenylmethane compounds, quaternary ammonium salts and the like are known.

[0003]

However, in the conventional toner, the effect of imparting charge to the charge controlling agent is not always sufficient. In particular, when the toner is repeatedly used for a long period of time, fog (image stain on a white background) and image density Drop, etc.,
There is a problem that image quality is deteriorated. Accordingly, an object of the present invention is to provide a toner for developing an electrostatic charge image having excellent charging characteristics, which gives a high-quality image even when used repeatedly over a long period of time. Another object is to provide a method for producing such a toner.

[0004]

Means for Solving the Problems The toner according to the present invention comprises:
It comprises at least a binder resin, a colorant and a quaternary ammonium salt, and has a surface concentration of the quaternary ammonium salt of 0.10 to 0.40.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The toner according to the present invention is mainly composed of a binder resin, a colorant and a quaternary ammonium salt as a charge controlling agent, similarly to a conventional toner. As the binder resin, a crosslinked or non-crosslinked styrene-based resin, a polyester-based resin, an epoxy resin,
Any one conventionally used as a binder resin for a toner can be used. If desired, some binder resins may be used in combination. Preferably, a styrene resin is used. Styrene-based resins are homopolymers or copolymers of styrene or styrene-substituted products, or copolymers of these styrene-based monomers and other monomers copolymerizable therewith, and various types are known. I have.

Some examples are polystyrene, chloropolystyrene, poly-α-methylstyrene,
Styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylate copolymer (styrene-acryl Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer and styrene-
Phenyl acrylate copolymer), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate) Copolymer, styrene-phenyl methacrylate copolymer), styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer and the like. As the styrene resin, a copolymer of styrene and another monomer copolymerizable therewith, in particular, an acrylate ester and having a styrene content of 70 to 95% by weight is preferably used.

The softening point of the binder resin is 70-160.
C., preferably 90 to 140C. Further, the glass transition temperature is preferably from 40 to 80C, particularly preferably from 50 to 70C. As the coloring agent, any commonly used coloring agent can be used.
For example, carbon black, benzidine yellow, quinacridone, rhodamine B, phthalocyanine blue and the like are used. The colorant is preferably contained in the toner in an amount of 0.1 to 20 parts by weight, particularly 0.5 to 10 parts by weight, based on 100 parts by weight of the binder resin. At least a quaternary ammonium salt is used as a charge control agent. Various quaternary ammonium salts are known,
Usually, acyclic quaternary ammonium salts represented by the following (I) to (VII), imidazolium salts, pyridinium salts,
Any of H-indolium salt, phenazinium salt, triethylenebisammonium salt or nitrilotriethyleneammonium salt is used.

[0008]

Embedded image

Wherein R _{1 to} R ₄ are each independently
A hydrocarbon group which may be substituted, X ^n- is an anion, n
Indicates a natural number. Preferably, R _{1 to} R ₄ each independently represent any of a C _{1 to} C ₂₂ optionally substituted aromatic hydrocarbon group, aromatic heterocyclic group or aliphatic hydrocarbon group. Particularly preferably, R _{1 to} R ₄ each independently represent a C _{1 to} C ₂₂ alkyl group or a benzyl group which may have a C _{1 to} C ₁₅ alkyl substituent on the benzene nucleus. As the anion represented by X ^n- , an anion commonly used for a quaternary ammonium salt may be used, and examples thereof include halogen ions such as chloride ion and bromine ion, methanesulfonate ion, ethanesulfonate ion, and propanesulfone. Alkyl sulfonic acid ion such as acid ion, benzene sulfonic acid ion, benzene disulfonic acid ion, naphthalene sulfonic acid ion, naphthalene disulfonic acid ion, naphthalene trisulfonic acid ion, toluene sulfonic acid ion, hydroxynaphthalene sulfonic acid ion, quinoline sulfonic acid ion Arylpolysulfonate ions such as dimolybdate ion, tetramolybdate ion, hexamolybdate ion, and octamolybdate ion; and heteropolyacid ions such as tungstophosphate ion. Preferably, a halogen ion, an alkyl sulfonate ion, or an aryl sulfonate ion optionally having a substituent in the nucleus is used. Table 1 shows some of the quaternary ammonium salts represented by the formula (I) that are preferably contained in the toner of the present invention.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

Embedded image

In the formula, R ₅ and R ₆ each independently represent a hydrogen atom or a hydrocarbon group which may be substituted, or R ₅ and R ₆ may be substituted by the combination of R ₅ and R _6. Has a good benzene ring. R ₇ represents a hydrogen atom or a hydrocarbon group which may be substituted. R ₈ and R ₉ each independently represent a hydrocarbon group which may be substituted. When any of R _{5 to} R _{7 is} a hydrocarbon group which may be substituted, its carbon number is 22.
It is preferred that: It is preferable that R ₈ and R ₉ each have 8 or less carbon atoms. X is an anion, n
Indicates a natural number. As the anion represented by X, the same anion as described for the quaternary ammonium salt represented by the formula (I) is used.

[0015]

Embedded image

In the formula, R ₁₀ represents an optionally substituted hydrocarbon group, and R ₁₁ represents a hydrogen atom or an optionally substituted hydrocarbon group. When R ₁₀ and R ₁₁ are an optionally substituted hydrocarbon group, R ₁₀ and R ₁₁ are each independently a C ₂₂ or less optionally substituted aromatic hydrocarbon group or an aromatic group. It is preferably an aromatic heterocyclic group or an aliphatic hydrocarbon group. And X ^- represents an anion, n represents a natural number, respectively. As the anion represented by X, the same anion as described for the quaternary ammonium salt represented by the formula (I) is used.

[0017]

Embedded image

In the formula, Y represents a carbon, sulfur or oxygen atom. When Y is a carbon atom, a substituent may be further bonded to Y. R _{12 to} R ₁₄ each independently represent a hydrogen atom or a hydrocarbon group which may be substituted, but R ₁₄ is not a hydrogen atom. As the optionally substituted hydrocarbon group represented by R _{12 to} R ₁₄ , each independently represents an optionally substituted aromatic hydrocarbon group having 22 or less carbon atoms, an aromatic heterocyclic group or an aliphatic group. It is preferably a hydrocarbon group. X represents an anion and n represents a natural number. As the anion represented by X, (I)
The same ones as described for the quaternary ammonium salt represented by may be used.

[0019]

Embedded image

In the formula, R _{15 to} R ₁₇ are each independently
A hydrogen atom or a hydrocarbon group which may be substituted is shown, but R ₁₅ is not a hydrogen atom. The optionally substituted hydrocarbon groups represented by R _{15 to} R ₁₇ each independently represent an optionally substituted aromatic hydrocarbon group having 22 or less carbon atoms, an aromatic heterocyclic group, or an aliphatic group. It is preferably a hydrocarbon group. X represents an anion and n represents a natural number. As the anion represented by X, the same anion as described for the quaternary ammonium salt represented by the formula (I) may be used.

[0021]

Embedded image

In the formula, R ₁₈ and R ₁₉ each independently represent a hydrocarbon group which may be substituted. Preferably, R ₁₈ and R ₁₉ are each independently an optionally substituted aromatic hydrocarbon group, aromatic heterocyclic group or aliphatic hydrocarbon group having 22 or less carbon atoms. X represents an anion and n represents a natural number. As the anion represented by X, the same anion as described for the quaternary ammonium salt represented by the formula (I) may be used.

[0023]

Embedded image

In the formula, R ₂₀ represents an optionally substituted hydrocarbon group, preferably an optionally substituted aromatic hydrocarbon group having 22 or less carbon atoms, an aromatic heterocyclic group or an aliphatic hydrocarbon group. Show. X represents an anion and n represents a natural number. As the anion represented by X, the same anion as described for the quaternary ammonium salt represented by the formula (I) may be used. In the above formulas I to VII, examples of the substituent of the hydrocarbon group represented by R include an alkyl group, an aryl group, an aralkyl group, a hydroxyl group, an amino group, and a halogen atom. Further, these alkyl groups, aryl groups, and aralkyl groups may be bonded to a hydrocarbon group via an oxygen atom, a sulfur atom, an amide group, or the like. 4th
The quaternary ammonium salt is preferably present in the toner in an amount of 0.1 to 10 parts by weight, particularly 0.5 to 5 parts by weight, based on 100 parts by weight of the binder resin.

The quaternary ammonium salt has a surface concentration of 0.1.
It is necessary to make it exist in the toner so as to be 10 to 0.40. If the surface concentration exceeds this range,
When the charge amount of the toner becomes small and the toner is repeatedly used, floating toner contaminates the inside of the developing machine, that is, so-called toner scattering occurs. Conversely, if the surface density falls below this range, the charging stability cannot be obtained, and stable image quality cannot be maintained when the toner is used repeatedly. A suitable range for the surface concentration is from 0.15 to 0.40, especially from 0.20 to 0.
40. The reason why the surface concentration of the quaternary ammonium salt has an appropriate range as described above is that the quaternary ammonium salt present on the toner surface is not only a charging point of the toner but also a point of loss of the charged electric charge. This is considered to be because the stability of the charge amount can be maintained only when the surface concentration is in an appropriate range. To keep the surface concentration of the quaternary ammonium salt in the above range, a binder resin,
This can be achieved by blending a colorant and a quaternary ammonium salt to form a mixture, and then appropriately adjusting the mixing conditions and kneading conditions for melt-kneading the mixture. That is, the toner according to the present invention can be produced by a conventional method in which a mixture is formed by blending a binder resin, a colorant and a quaternary ammonium salt, and then the mixture is melt-kneaded, then pulverized and classified. If the mixing time is increased or the binder resin and the quaternary ammonium salt are first mixed and then the remaining colorant and the like are mixed, the surface concentration of the quaternary ammonium salt may be reduced. Can be. In addition, during the melt kneading, if the kneading conditions are strengthened such as increasing the screw rotation speed of the twin-screw extruder, the surface concentration of the quaternary ammonium salt decreases,
Increasing the kneading temperature increases the surface concentration of the quaternary ammonium salt.

In the production of the toner according to the present invention, the quaternary ammonium salt has a specific volume of 3.0 m.
It is preferable to use one that satisfies at least one of the following conditions: 1 / g or more, or an average particle size of 15 μm or less, particularly 10 μm or less. Such a quaternary ammonium salt has good dispersibility, and is easily dispersed uniformly during mixing and melt-kneading. In addition,
The specific volume is also related to the particle size, and in general, the larger the specific volume, the smaller the average particle size. However, since the specific volume is also affected by the particle size distribution, the specific volume and the average particle size are 1: 1.
It does not necessarily correspond.

The toner according to the present invention consists essentially of the above-mentioned binder resin, colorant and quaternary ammonium salt, but may further contain various conventional auxiliaries. For example, various plasticizers and release agents can be added to adjust the thermal characteristics or physical characteristics of the toner. These auxiliaries are usually contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the binder resin. Further, by adding a fine powder of titania, alumina, silica, etc. to the toner particles to coat the surface of the toner particles,
The fluidity and aggregation resistance of the toner can be improved. The addition amount of these fine particles is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the binder resin. Further, in the toner, a solid electrolyte, a polymer electrolyte, a charge transfer complex,
Conductors and semiconductors made of metal oxides such as tin oxide,
Alternatively, a ferroelectric substance, a magnetic substance, or the like may be contained to control the electrical properties.

The toner according to the present invention can be produced by various methods conventionally used in the production of toner. Usually, a binder resin, a colorant, a quaternary ammonium salt and other auxiliaries are blended, and a ball mill,
Mix well with a V-type mixer, S-type mixer, Henschel mixer or the like to obtain a uniform composition. Next, this is melted and kneaded with a double arm kneader, a pressure kneader or the like. After cooling the melt-kneaded product, it is pulverized by a hammer mill, jet mill, ball mill or the like, and the obtained powder is classified by an air classifier to obtain a product having a predetermined particle size range as a product. The particle size of the toner is usually 1 to 30 μm.

The obtained toner can be used as a one-component developer or a two-component developer for copying by electrophotography. As a carrier when used as a two-component developer, a magnetite carrier or a ferrite carrier may be used. Both can be mixed and used,
It is preferable to use each alone. Examples of the ferrite carrier include CuOFe ₂ O ₃ ZnO and NiO
Although Fe ₂ O ₃ ZnO is used, it is of course possible to use other materials. The carrier may be used after being coated with a resin or the like. As the coating resin, for example, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer,
Fluorinated resins such as vinylidene fluoride-trifluoroethylene copolymers, silicone resins, styrene-acrylic copolymers and the like are used. Further, a metal oxide may be used instead of the resin. The particle size of the carrier is usually 50-30.
0 μm. The carrier may usually be used in an amount of 10 to 100 parts by weight based on 1 part by weight of the toner.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the present invention, the surface concentration of the quaternary ammonium salt, the average particle diameter of the particles and the specific volume are measured as follows. 50 ml of room temperature ethanol is placed in a sample bottle with a quaternary ammonium salt having a surface concentration of 50 ml, and 0.1 g of the toner is added thereto. This is subjected to a dispersion treatment for 3 minutes by an ultrasonic disperser having an output of 65 W. Then KUB
After centrifuging at 1000 rpm for 10 minutes using OTA KR / 600 (manufactured by Kubota Corporation) to precipitate the solid, the absorbance of the supernatant was measured,
The amount of quaternary ammonium salt is determined, and this is defined as the amount of quaternary ammonium salt (A ₁ ) present on the toner surface. Next, the quaternary ammonium salt eluted in the same manner as above except that tetrahydrofuran is used instead of ethanol is quantified, and this is defined as the total amount of quaternary ammonium salt (A ₂ ) present in the toner. From the above two measured values, the surface concentration of the quaternary ammonium salt is calculated by the following equation.

[0031]

## EQU1 ## Surface concentration of quaternary ammonium salt = A ₁ / A ₂

The average particle diameter of the particles is measured by a dry method using a laser diffraction type particle size distribution analyzer. The average particle size of the examples is Sympatech (Germany)
Laser diffraction particle size distribution analyzer (HEROS & RO)
DOS) under the following conditions. Dispersion method; Flow-type dispersion unit Dispersion air pressure; 3 bar Lens focal length; 500 mm Measurement time: 3 seconds Specific volume About 5 g (Wg) of quaternary ammonium salt is placed in a glass measuring cylinder (inner diameter 21 mm, height 220 mm), and After dropping five times from a position of 100 mm onto a wooden desk, the volume (Vml) is read from the scale of the measuring cylinder, and the specific volume is calculated by the following equation.

[0033]

## EQU2 ## Specific volume = V / W (ml / g)

Example 1 Using a Henschel mixer, 100 parts by weight of a styrene-n-butyl acrylate copolymer (styrene content: 85.0% by weight) having a softening point of 130 ° C. and a glass transition point of 59.1 ° C. No. of Table-1. 6 parts by weight of a quaternary ammonium salt (average particle size: 5.7 μm, specific volume: 3.2 ml / g), and 3 parts by weight of a polypropylene wax (“Viscol 550P” manufactured by Sanyo Chemical Co., Ltd.) And carbon black (Mitsubishi Chemical's "MA100S") 6
Parts by weight were added and mixed. This was melt-kneaded using a twin-screw extruder, and the kneaded material was cooled and solidified, coarsely ground with a hammer mill, and then finely ground with an ultrasonic jet mill. The pulverized product was classified with an air classifier, and a portion having a particle size of 5 to 30 μm was obtained as toner particles. 100 parts by weight of the toner particles are coated with hydrophobic silica (Aerosil R manufactured by Nippon Aerosil Co., Ltd.).
−972 ”) is added to the surface by adding 0.2 parts by weight,
The toner was used. This toner had an average particle diameter of 10.3 μm and a surface concentration of the quaternary ammonium salt of 0.29.

Example 2 Styrene having a softening point of 132 ° C. and a glass transition point of 56.1 ° C.
N-butyl acrylate copolymer (styrene content 7
3.2% by weight) 100 parts by weight; 6th 4th
Grade ammonium salt (average particle size 5.7 μm, specific volume 3.2
ml / g) 2 parts by weight, polypropylene wax (Viscol 550P) 3 parts by weight and carbon black (MA1
00S) 6 parts by weight were mixed, mixed with a Henschel mixer for 30 minutes, and then melt-kneaded using a twin-screw extruder. Thereafter, the same treatment as in Example 1 was performed to prepare a toner. This toner had an average particle diameter of 10.2 μm and a surface concentration of the quaternary ammonium salt of 0.23.

Example 3 Example 1 was repeated except that a styrene-n-butyl acrylate copolymer having a styrene content of 81.1% by weight, a softening point of 128 ° C. and a glass transition point of 58.1 ° C. was used. A toner was prepared in the same manner as described above. This toner has an average particle size of 10.
0 μm, and the surface concentration of the quaternary ammonium salt was 0.39.

Comparative Example 1 Except that a styrene-n-butyl acrylate copolymer, a quaternary ammonium salt, a polypropylene wax and carbon black were blended, mixed for 10 minutes with a Henschel mixer, and then melt-kneaded with a twin-screw extruder. In the same manner as in Example 1, a toner was prepared. This toner has an average particle size of 1
0.3 μm, surface concentration of quaternary ammonium salt 0.53
Met.

Comparative Example 2 As the quaternary ammonium salt, 6, except that the compound having an average particle size of 50 μm was used.
A toner was prepared in the same manner as in Example 1. This toner had an average particle size of 10.0 μm and a surface concentration of quaternary ammonium salt of 0.44.

Evaluation of Toner A fixing device comprising a photoreceptor having an organic photoconductive layer, a thin layer of Teflon resin coated on silicon rubber and an upper heat roller having a heater inside, and a lower pressure roller made of syringe rubber. The performance of the toner prepared above was tested using a copier having a copy speed of 60 sheets / min with the apparatus. The toner was mixed with a carrier (resin-coated ferrite) and supplied to a copying machine as a developer having a toner concentration of 4.0% by weight. The atmosphere is at a temperature of 23-25 ° C,
The relative humidity was 50 to 60%, and the fixing temperature was set at 190 ° C. No release liquid such as silicone oil was used.
Table 2 shows the results. In Table 2, fogging was performed at Z / 1.1823 using a color difference meter. Where Z
Is Z on the XYZ indicator.

[0040]

[Table 4]

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobutada Fujitake 1 Fukudacho, Joetsu-shi, Niigata F-term in Naoetsu Works, Mitsubishi Chemical Corporation (reference) 2H005 AA01 AA06 AB04 CA03 CA04 CA05 CA07 CA08 CA28 DA03 EA05 EA10

Claims (5)

[Claims] 1. An electrostatic image developing method comprising at least a binder resin, a colorant and a quaternary ammonium salt, wherein the quaternary ammonium salt has a surface concentration of 0.10 to 0.40. toner. 2. The method according to claim 1, wherein the surface concentration of the quaternary ammonium salt is 0.1.
The toner for developing an electrostatic image according to claim 1, wherein the toner has a particle diameter of 20 to 0.40. 3. The electrostatic image developing toner according to claim 1, wherein the quaternary ammonium salt is represented by the following formula. Embedded image (Wherein, R _{1 to} R ₄ each independently represent a hydrocarbon group which may be substituted. X ^n- represents an anion;
n indicates a natural number. ) 4. The toner for developing an electrostatic image according to claim 1, wherein the binder resin is a styrene-based resin. 5. A method for producing a toner for developing an electrostatic charge image, comprising forming a mixture by blending at least a binder resin, a colorant and a quaternary ammonium salt, melting and kneading the mixture, and then pulverizing and classifying the mixture. As a grade ammonium salt,
The electrostatic image according to any one of claims 1 to 4, wherein a material having a specific volume of at least 3.0 ml / g or an average particle size of at most 15 µm which satisfies at least one of the conditions is used. A method for producing a developing toner.