JPH0810362B2 - Developer for electrostatic image - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developer for electrostatic charge images using a charge exchange control agent.

More specifically, it relates to a developer that visualizes an electric latent image and an electric signal in electrophotography, electrostatic recording, etc., and particularly relates to a developer having excellent chargeability (mainly negative chargeability), developability and transferability.

Conventional technology Developer (toner) that visualizes charge latent images and electrical signals
As a method for imparting an electric charge to the friction contact charging method,
Various methods such as an ion irradiation method, an electrostatic induction method using conductivity, and a charge injection method are known.
Further, the friction contact charging method is widely used.

As the developer used in the friction contact charging method, in addition to a two-component developer in which carrier particles having a polarity opposite to that of the toner in order to impart an electric charge to the toner are mixed with the toner,
There is also known a one-component developer that utilizes frictional electrification between a charging member such as a charging blade or a charging roll and toner, or frictional electrification between toners.

Problems to be Solved by the Invention When the toner is charged by such a contact charging or friction charging method, an electron-donating substance or an electron-attracting substance is attached to the toner side or the charge-giving material side such as a carrier or a blade. Is added to control the chargeability. The triboelectrification phenomenon is complicated, and although this mechanism is not always clear, generally, the electron-donating substance is positively charged and the electron-withdrawing substance is negatively charged.

Conventionally, in order to control the charging of the toner, (i) a dye or pigment, a surfactant,
Inorganic powder and the like are added and mixed, (ii) as a binder resin,
COOH, -CN, halogen such as-C1, -NO _2, a resin-like material having a functional group such as -NH _2, but means the like have been taken, over time stability of the toner charging property, The control of environmental stability was not successful and was not satisfactory.

In addition, there was no good charge control agent which is colorless or light and can be used for color development.

Therefore, an object of the present invention is to provide a developer containing a charge exchange control agent which can solve the above-mentioned problems.

Another object of the present invention is to provide a developer which has a fast rise of charging and which can easily control the amount of charge and the charge distribution.

Another object of the present invention is to provide a developer which has excellent environmental stability of chargeability and stability over time, has improved developer and transferability, and ensures good image quality.

Still another object of the present invention is to provide a color developer in which charging rises quickly and the amount of charge and charge distribution can be easily controlled.

Means for Solving the Problems As a result of intensive studies, the present inventors have found that (i) carrier particles containing a silicone resin on the surface and / or inside, and (ii)
It has been found that a developer prepared by mixing toner particles containing a specific organoboron compound can solve and overcome the above problems, and completed the present invention.

Therefore, the developer for electrostatic images of the present invention has a neutralized salt structure of (i) carrier particles containing a silicone resin on the surface and / or inside, and (ii) a boron-containing organic anionic component and a cationic component. It is characterized in that toner particles containing an organoboron compound represented by the following general formulas (a) to (h) are mixed.

(In the formula, R represents an organic group,₁Is a hydrogen atom, halo
Gen atom, alkyl group, halogenated alkyl group, aryl
Represents an alkyl group or an aryl group, M Is a cation
And n represents an integer of 1 or more, provided that
When n represents an integer of 2 or more, R₁Of each other
It may be the same or different.
Yes. ) Hereinafter, the present invention will be described in detail.

In the present invention, the silicone resin contained on the surface and / or inside of the carrier particles means a polymer of an organic silicon compound, has a siloxane bond in the molecule, and is further derived from alkyl, aryl or a silicon atom in the silicon atom. It is a polymer having a side chain to which a group is bonded. The silicone resin may be a graft polymer or a copolymer having a siloxane bond portion in the side chain, or a block polymer or a copolymer having a siloxane bond portion in the main chain. It may be a mixture of a polymer and another polymer. As another form, it may be a polymer in which a prepolymer having a siloxane bond portion is crosslinked and singulated by heating and / or radiation. A modified silicone resin such as an acrylic modified silicone resin or an epoxy modified silicone resin can also be used. Examples of commercially available silicone resins include, for example, Shin-Etsu Chemical Co., Ltd.'s KR216, KR255, KR295 and Toray Lecicorn's SH840,
There are SR2400, SH6018, etc.

Carrier particles are prepared using these silicone resins. For example, an iron powder having a particle size of about 20 μm to 200 μm, obtained by mixing a silicone resin alone or with another resin,
Ferrite powder, alumina powder, silica powder, glass beads,
Desired carrier particles can be prepared by coating the surface of nickel powder, magnetite powder or the like. As a method for coating the above-mentioned silicone resin on these surfaces, known methods such as a spray drying method, an air suspension coating method, and a method using a kneader coater can be used. Further, the coating may be a complete coating or a partial coating. As a quantitative ratio of the silicone resin coating on the surface of the carrier particles, the silicone resin is 0.01 to 5 with respect to the carrier particles.
The coating is performed so as to have a weight percentage. Also, the particle size is about 0.01
By mixing ferrite fine powder, iron oxide fine powder, etc. having a size of from about 2 μm to about 2 μm with the solution, melt, emulsion, etc. of the above-mentioned polymers, granulating and drying, a particle size of about 20 is obtained.
You may prepare the composite carrier which the ferrite particle | grains etc. of about 200 micrometers are disperse | distributed in resin. Furthermore, a similar separation type composite carrier may be prepared by polymerizing a prepolymer of a silicone resin in the presence of ferrite fine powder.

In the present invention, the general formula (a) used for the toner is used.
In the organoboron compound represented by (h) to (h), the cationic component is an alkali metal cation such as Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Be ²⁺ , Mg ²⁺ , Ca ^2+. , Sr ²⁺ , Ba ^{2+ and} other alkaline earth metal cations, Cu ⁺ , Ag ⁺ , Zn ²⁺ , Cd ²⁺ and other transition metal cations, other polyvalent metal cations, ammonium, alkylammonium, pyridinium , Alkylpyridinium, quinolinium, imidazolinium, and other organic amine cations, organic phosphonium cations, sulfonium cations, and the like. However, since the function of the charge control agent of the present invention depends on the size and strength of the cationic component, care must be taken in selecting the cationic component. Particularly, when the amount of the cationic component is large, the toner has a positive charging property, so that special attention is required. For the purpose of the present invention, among the above anionic components, metal cations, ammonium cations (N
H ₄ ⁺ ) is most suitable, and when organic amine cations and organic phosphonium cations are used, cations having the following structures are conveniently used.

(R ₄ to R ₇ each represent hydrogen, a lower alkyl group such as a methyl group, an ethyl group and a butyl group, an arylalkyl group such as a benzyl group, an aryl group such as a phenyl group and a tolyl group.) Alkylpyridinium Even if the cation has a long chain alkyl group, the function of the charge control agent of the present invention is sufficiently exerted.

Among the organoboron compounds used in the present invention, preferred are compounds represented by the above formula (a).

Further, typical compounds include compounds represented by the following general formula (I).

(In the formula, R ₂ represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated methyl group, R ₃ represents a hydrogen atom or a halogenated methyl group, and M ₁ ⁺ represents a metal cation or an ammonium cation. ) Specific examples thereof will be illustrated below.

Tetraphenylboron lithium Tetraphenylboron sodium Tetraphenylboron potassium Tetraphenylboron rubidium Tetraphenylboron cesium Tetraphenylboron silver Tetraphenylboron calcium Tetraphenylboron ammonium Tetra (p-fluorophenyl) boron lithium Tetra (p-fluorophenyl) boron sodium Tetra (p-fluorophenyl) boron potassium Tetra (p-fluorophenyl) boron rubidium Tetra (p-fluorophenyl) boron cesium Tetra (p-fluorophenyl) boron silver Tetra (p-fluorophenyl) boron calcium Tetra (p-fluorophenyl) boron ammonium Tetra (p-chlorophenyl) boron lithium Tetra (p-chlorophenyl) Sodium iodine Tetra (p-chlorophenyl) boron potassium Tetra (p-chlorophenyl) boron rubidium Tetra (p-chlorophenyl) boron cesium Tetra (p-chlorophenyl) boron silver Tetra (p-chlorophenyl) boron calcium Tetra ( p-Chlorophenyl) boron ammonium tetra (p-tolyl) boron lithium tetra (p-tolyl) boron sodium tetra (p-tolyl) boron potassium tetra (p-tolyl) boron rubidium tetra (p-tolyl) boron Elementary cesium tetra (p-tolyl) boron silver tetra (p-tolyl) boron calcium tetra (p-tolyl) boron ammonium tetrakis [3,5-bis (trifluoromethyl) phenyl] boron lithium tetrakis [3, 5-bis (trifluoromethyl) phosphine Nyl] boron sodium tetrakis [3,5-bis (trifluoromethyl) phenyl] boron potassium tetrakis [3,5-bis (trifluoromethyl) phenyl] boron rubidium tetrakis [3,5-bis (trifluoromethyl) ) Phenyl] boron cesium tetrakis [3,5-bis (trifluoromethyl) phenyl] boron silver tetrakis [3,5-bis (trifluoromethyl) phenyl] boron calcium tetrakis [3,5-bis (trifluoro) Methyl) phenyl] boron ammonium As described above, the developer of the present invention comprises the above-mentioned specific boron-containing organic anion component (A) utilizing the electron accepting property of boron.
The main feature is to use. Therefore, it can be effectively used mainly for controlling the negative charging property and promoting charge exchange of the negative charging material. However, depending on the method of use, the above-mentioned organoboron compound may be added to the positively chargeable material to further improve the charge exchange property and to control the conductivity of the material.

The charge polarity of these organoboron compounds (AD) is considered to be determined by the composition or molecular size of the organic anion component (A) and the cationic component (D) that form the compound (AD), respectively. Depending on the composition of the component (D) or when the molecular size of the cationic component (D) is large, the neutralizing salt type compounds (AD) of both are not the negative charge controllability but rather the positive charge controllability. Is easily expressed. In such a case, the characteristics of the compound are determined by the component (D) rather than the component (A).

In the present invention, the organoboron compound may be a single compound, or may be a mixture of two or more compounds or a solid solution.

Many of the organoboron compounds in the present invention are colorless or light-colored and have excellent charge controllability.
In addition to the black developer, it can be used very well for the charge control of a material such as a color developer which is not colored.

The organoboron compound has a melting point or softening point of about 50.
It is desirable to use a substance that is solid at room temperature above ° C. However, depending on the method of use, such as when treating only the surface layer of the toner particles, liquid substances can also be used. Furthermore, the liquid substance is an inorganic fine powder, a resin fine powder, a porous substance,
It can also be used after being apparently solidified by being supported or impregnated with a gelling agent or the like.

The organoboron compound is added to the toner particles in an amount of about 0.01% by weight to about 10% by weight, preferably about 0.1% by weight to about 5% by weight. As a result, it is possible to very favorably improve the electric property of the developer.

As a method of addition to the toner particles, not only dispersing or dissolving inside the toner particles, but addition to the toner particle surface layer only, or addition to the outside of the toner particles and mixing may be performed.

When it is added and mixed into the toner particles, it is mechanically mixed with the binder resin by a method such as melt mixing, emulsion mixing, and solution mixing, and the binder resin is polymerized in the presence of the organoboron compound to form a binder. The organoboron compound may be mixed or dissolved in the resin. In this case, a chemical bond may occur between the organoboron compound and the binder resin or other additives in the toner particles.

As the binder resin for the toner particles, conventionally known ones can be used. For example, styrenes such as styrene, chlorostyrene and vinyl styrene; monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate and acrylic acid. Ethyl, butyl acrylate, dodecyl acrylate,
Octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate,
Α, β-Unsaturated acid esters such as dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; homopolymers of vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. or An example is a copolymer. Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Polymers, polyethylene, polypropylene can be mentioned.

Furthermore, polyester, polyurethane, epoxy resin, silicone resin polyamide, modified rosin, paraffin and waxes can be mentioned.

Examples of the colorant include black dyes and pigments such as carbon black, oil black, and graphite; acetoacetic acid arylamide monoazo yellow pigments such as CI Pigment Yellow 1, 3, 74, 97, and 98 (Fast Yellow) ); CI Pigment Yellow 12, 13, 13 and 14 acetoacetic acid arylamide disazo yellow pigments; CI Solvent Yellow 19, 77, 79, CI Pigmate Red 48, 49:
Red or red pigments such as 1, 53: 1, 57: 1, 81, 122, 5 and the like; CI solvent red 52, 58, 8 and other red dyes; CI Pigmate Blue 15: Blue dyes and pigments such as copper phthalocyanine and its derivatives and modified products, and colored or colorless sublimable dyes can be used as well as printing inks and other conventionally known dyes for coloring.

These dyes and pigments may be used alone or in combination of two or more. Of course, the color tone may be adjusted by mixing with an extender pigment or a white pigment. Furthermore, in order to improve the dispersibility in the binder component, the surface of the colorant is treated with a coupling agent such as a surfactant or a silane coupling agent, a polymer material, a polymer dye or a polymer graft pigment. May be used.

The binder resin and the colorant are not limited to those exemplified above.

Further, the toner particles in the present invention can be used as a magnetic toner by including a magnetic material (for example, ferrite) therein.

In addition, the toner particles in the present invention, it is also possible to use a conventionally known charge control agent as another additive, also a conductivity adjusting agent, an inorganic substance such as a metal oxide, a reinforcing filler,
Antioxidants and the like can also be used.

Further, as an external additive, silica, carbon, alumina,
Conventionally known substances such as titanium oxide, zinc oxide, resin fine powder, tin oxide, higher fatty acids and derivatives thereof such as metal salts can be used.

The toner particles in the present invention can be manufactured by any method such as a kneading and pulverizing method, a spray drying method and a direct polymerization method.

The particle size of the toner particles is such that the average particle size d50 measured by the Coulter counter method is 1 to 20 μm, preferably 5 to 15 μm.
Something good.

Action Conventionally, when carrier particles having a low surface energy such as silicone resin are used, there is an advantage that the carrier particles are less likely to be contaminated by the toner or the toner component, and the effect of extending the life of the developer is great. The carrier particles also had the disadvantage of poor charging.

However, when used in combination with toner particles containing an organoboron compound in the present invention, the good chargeability of the organoboron compound does not simply cover the poor chargeability of the silicone resin-based carrier particles, but rather In addition to exhibiting good chargeability, the deterioration resistance which is a characteristic of the silicone resin system is not impaired. Although the reason for this is not clear, an organoboron compound (AD) having a neutral salt structure of a boron-containing organic anionic component (A) and a cationic component (D) is (i) an electron accepting agent for boron. , (Ii)
Due to the effect of the neutralized salt type structure and (iii) the organic functional group, exchange and transfer of electrons and / or ions of the compound itself and the composite material in which the compound is dispersed or dissolved in a polymer or the like are promoted, and an excellent charge is obtained. It is presumed that it exhibits exchange controllability. It is considered that the organoboron compound and the siloxane structure of the silicone resin act additively on the microscopic environment in the vicinity of the developer, and exhibit very good chargeability.

Examples Hereinafter, the present invention will be described with reference to examples, but of course, the contents of the present invention are not limited to these examples. Unless otherwise specified, "part" in the examples is
Represents "parts by weight". Also, normal temperature and humidity are 22 ° C and 55% R.
H., high temperature and high humidity 28 ° C, 85% RH, low temperature and low humidity 10 ° C,
It means an environment of 15% RH.

Example 1 100 parts of dimethylpolysiloxane / methyl methacrylate = 5/4 graft copolymer 50 parts of methyl methacrylate 0.5% by weight of the above components dissolved in methyl ethyl ketone.
Then, the surface of the spherical ferrite powder having an average particle diameter of 120 μm was coated with a kneader coater to obtain carrier particles. On the other hand, the following components were melted and kneaded, pulverized and classified to obtain toner particles having an average particle size of 7 μm.

Styrene / n-butyl acrylate 100 parts Copolymer Cyan pigment (copper phthalocyanine) 6 parts Tetraphenylboron potassium 1 part The obtained carrier particles and toner particles were mixed at a weight ratio of 100/2 to prepare a developer. When the charge properties were compared by the charge spectrograph method, the results shown in the table below were obtained.

Next, an FX-2300 copying machine (manufactured by Fuji Xerox Co., Ltd.) using the above-mentioned toner particles, in which 1.0 wt% of hydrophobic silica fine powder and 0.5 wt% of polymethylmethacrylate fine powder are externally added and the above-mentioned carrier particles are used. ) And performed a copy test of 30,000 sheets. As a result, stable and good images were obtained up to 30,000 sheets.

Comparative Example 1 A developer was prepared and measured in the same manner as in Example 1 except that the carrier particles of Example 1 were changed to ferrite particles coated with a methyl methacrylate homopolymer.

Next, the toner particles treated in the same manner as in Example 1 and the carrier particles were mounted on an FX-2300 copying machine, and a copying test of 30,000 sheets was conducted.
Fog began to appear from the point where the number of sheets exceeded, and it became a bad image when the number of sheets became 5000.

Comparative Example 2 Cyan toner particles having an average particle size d50 = 7 μm obtained by removing only tetraphenylboron potassium from the toner particles of Example 1 were prepared and used as a combined developer with the carrier particles of Example 1 and evaluated in the same manner. As a result, the environmental stability was poor as shown below, and the buildup of charging and the stability over time were completely poor.

Example 2 A 0.5 wt% solution of polymethylphenylsiloxane resin (KR-295, manufactured by Shin-Etsu Chemical Co., Ltd.) was coated on the surface of spherical ferrite powder having an average particle diameter of 100 μm using a fluidized bed coating device to obtain carrier particles. .

On the other hand, the following components were melt-kneaded, pulverized and classified to obtain toner particles having an average particle size of 7 μm.

Polyester 100 parts Magenta pigment (Carmine 6B) 6 parts Sodium tetraphenylboron 1 part Using the carrier particles and the toner particles, the same measurements as in Example 1 were carried out. As a result, normal temperature and normal humidity, high temperature and high humidity, and low temperature and low humidity were obtained. The good charging method was around −20 μc / g in all environments. Further, 1.0 wt% of hydrophobic silica fine powder was externally added to and mixed with the magenta toner particles and the carrier particles were mounted on an FX-2300 copying machine, and a copying test of 10,000 sheets was conducted. A good image was obtained.

Example 3 Bisphenol A type epoxy resin 100 parts (epoxy equivalent 940, melting point 103 ° C.) Yellow pigment (Fast Yellow G) 6 parts Sodium tetraphenylboron 1 part The above components are melt-kneaded, ground and classified to have an average particle size of 7 μm.
Toner particles were obtained. Using the toner particles and the carrier particles of Example 1, the same measurement as in Example 1 was carried out. As a result, it was found to be −20 μ in all environments of normal temperature and normal humidity, high temperature and high humidity, and low temperature and low humidity.
It showed a good charging method of around c / g. Further, 1.0 wt% of hydrophobic silica fine powder and 0.5 wt% of tin oxide fine powder were externally added and mixed to the yellow toner particles, and the carrier particles of Example 1 were used and mounted on an FX-2300 copying machine. A copy test was performed on 3000 sheets, but good images were always obtained.

Example 4 Styrene / n-butyl acrylate 100 parts Copolymer carbon black 10 parts Polypropylene wax 5 parts Tetraphenylboron ammonium 1 part The above components are melt-kneaded, ground and classified to have an average particle size of 7 μm.
Toner particles were obtained. The black toner particles, to which 1.0 wt% of hydrophobic silica fine powder was externally added, and the carrier particles of Example 2 were mounted on an FX-3800 copying machine (manufactured by Fuji Xerox Co., Ltd.) to obtain 10,000 sheets. A copy test was carried out and a good image was always obtained.

EFFECTS OF THE INVENTION The toner particles containing a charge exchange control agent composed of an organoboron compound composed of a boron-containing organic anionic component and a cationic component according to the invention have very good chargeability themselves. However, in the present invention, the toner particles are used in combination with the carrier particles containing the silicone resin, so that the chargeability of the toner particles becomes extremely good, and the raw material which was conventionally impossible to control the charge. Can also be enabled.

Therefore, the developer of the present invention has a rapid rise in charging,
It has an appropriate charge amount and charge distribution, and is excellent in environmental stability and temporal stability. Particularly, it is excellent when used as a negatively chargeable developer.

Further, most of the organoboron compounds in the present invention are colorless or light-colored, and therefore the developer of the present invention is also suitable as a color developer.

Claims (2)

[Claims] 1. (i) Silicone resin on the surface and / or inside
Particles contained in the part, and (ii) boron-containing organic anion
The following one having a neutralized salt structure of a cationic component and a cationic component
Includes organoboron compounds represented by general formulas (a) to (h)
An electrostatic charge image developer formed by mixing toner particles. (In the formula, R represents an organic group,₁Is a hydrogen atom, halo
Gen atom, alkyl group, halogenated alkyl group, aryl
Represents an alkyl group or an aryl group, M Is a cation
And n represents an integer of 1 or more, provided that
When n represents an integer of 2 or more, R₁Of each other
It may be the same or different.
Yes. ) 2. An organoboron compound represented by the following general formula (I):
A compound represented by claim 1
Developer for electrostatic images.(Where R₂Is a hydrogen atom, halogen atom, lower alkyl
Group or halogenated methyl group, R₃Is a hydrogen atom or
Represents a halogenated methyl group, M₁ Is a metal cation or
Represents an ammonium cation. )