JPH0695224B2 - Developer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a dry developer for directly visualizing an electric latent image or an electric signal in electrophotography, electrostatic recording, etc., in particular, toner particles without using carrier particles. And a positively chargeable one-component developer using

[Conventional technology]

A method for forming an electric latent image is well known in the art. For example, in electrophotography, usually, after charging a photoconductor layer, a photoimage based on an original image is irradiated to reduce the electrostatic charge of a light irradiation portion. It disappears to form an electrostatic latent image.

Next, this latent image is developed with a developer called toner. As is well known, the developing method is roughly classified into a method using a wet developer and a method using a dry developer. The latter is a two-component developing method using two kinds of particles of a carrier and a toner and a one-component method using only a toner. Development method.

The two-component developer imparts an electric charge to the toner particles by the contact frictional charging between the carrier particles and the toner particles. Therefore, it is possible to control the charge of the toner relatively easily by selecting the materials of the carrier and the toner, and it is the mainstream of the current developing methods. However, since triboelectrification is adopted as the charging principle, the charging property changes over time due to repeated use and the developer deteriorates, and there is a difference in charging property between high temperature and high humidity and low temperature and low humidity. However, it has the drawback that it cannot be used stably in all environments. Further, not only the toner particles but also the carrier particles are used together, so that the developing device portion becomes large and heavy, and the cost also increases.

In order to solve such a problem, in recent years, a one-component developer that does not use carrier particles has been reviewed and research and development have been actively conducted. In the case of a one-component developer, since only toner particles are used, how to impart a charge to the toner becomes a problem. When a relatively conductive toner is used to apply a charge to the toner by electrostatic induction, a change over time in charging such as triboelectric charging and environmental dependence can be ignored, and good developing performance can always be obtained. However, since a conductive or semi-conductive toner is used, transfer onto paper or the like cannot be performed well.

A method of applying an electric charge to a toner by contact between a developing device member such as a blade or a developing device sleeve and toner, frictional charging, or frictional charging between toner particles has been proposed and put into practical use. However, the disadvantages of the conventional two-component developer, such as the change in chargeability over time and the dependence on the environment, have not been essentially eliminated. Using a corotron,
The method of charging the toner by ion irradiation also has many practical problems such as uneven charging, corotron contamination, and ozone generation.
A method utilizing dielectric polarization has also been proposed, but in this case, only a portion where the change in electric field strength is large can be developed in principle, which is not general.

As described above, the conventional one-component developing method and the developer cannot sufficiently satisfy the charging, developing property and transferability of the toner, and they are not enough to solve the defects of the two-component developing method and the developer. . From the viewpoint of the developer material, the conventional two-component developer uses two types of carrier particles and toner particles in combination, and separates the function as a developer between them.
On the other hand, in the one-component developer, it is necessary to further add to the toner the function that was conventionally shared by the carrier particles so as to share the function separation inside the toner. However,
At present, a material design guideline for a multi-functional one-component developer that satisfies such requirements is not yet established.

[Problems to be solved by the invention]

An object of the present invention is to provide a developer composition having excellent chargeability and developability even when carrier particles are not used.

Another object of the present invention is to provide a developer composition having excellent developability and transferability.

Still another object of the present invention is to improve charging, developing, transferability by temperature,
It is to provide a developer composition that is stable against environmental changes such as humidity.

Still another object of the present invention is to provide a developer composition which does not undergo changes in charging, development and transfer properties upon repeated use and is substantially free from changes over time and deterioration.

Still another object of the present invention is to provide a developer composition capable of forming a good and stable image in any image forming process.

Still another object of the present invention is to provide a developer composition having excellent developability and transferability regardless of the material of the organic or inorganic photosensitive material.

[Means and Actions for Solving Problems]

The above-mentioned object is to provide an electron-withdrawing or anionic component (at least in the outermost layer of the insulating particles (B) containing as an essential component a binder resin containing a monomer component represented by the following general formula (A). This can be achieved by forming a discontinuous layer of titanium oxide having C), and further adjusting the electric resistivity of the entire developer particles to 10 ¹⁴ Ωcm or more.

General formula (A): In the formula, R ₁ is a hydrogen atom or a methyl group, and R ₂ and R ₃
May be the same or different and are a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, but R ₂ and R ₃ do not represent a hydrogen atom at the same time, and n is an integer of 1 to 4. .

Regardless of whether it is a magnetic toner or a non-magnetic toner, the charging and developing mechanism of a high-resistance one-component developer is generally complicated, and with some exceptions, its physical properties have not been sufficiently clarified. This is because the high-resistance single-component developer is a composite material particle in an electrically dielectric region, which makes it difficult to handle scientifically, and a high electric field and a short-time phenomenon in the image forming process such as development and transfer. Yes, and during that time the developer is not stationary, but is based on the complexity of the phenomenon of motion.

In other words, stable charge application to a high-resistance one-component developer, control of developability and transferability means high electric field (usually 10 ³ to 10 ⁵
This can be understood as a problem of how to precisely control and design the electrical response of the developer in a short time (about 10 ^-1 to 10 ^-3 seconds) in V / cm).

The present inventors, as a result of diligent studies, coexisted with titanium oxide having a nitrogen-containing polar functional group and an electron-withdrawing or anionic component on the surface of the developer particles, and further the electric resistivity of the developer particles was 10 ¹⁴ Ωcm. It has been found that a positively chargeable developer composition having extremely good and stable charging, developing and transferring properties can be obtained by the above adjustment. The positively chargeable developer of the present invention can be applied to, for example, a developing area (electric field of about 10 ⁴ V / cm, time 10
^{-Around 2} seconds), the electric charge is instantly obtained, and solid black, thin line,
It has excellent gradation reproduction, gives a good developed image without contamination of non-image area, and shows no change with time even after repeated use.
In addition, from a low temperature and low humidity environment where the temperature is 10 ° C and the humidity is about 15%, the temperature is 30
Charging, developing, and transferability are extremely stable even in high-temperature and high-humidity environments at 85 ° C and 85% humidity. By the way, even in a high temperature and high humidity environment, the electrostatic transfer rate is about 80% or more, and there is no deterioration in image quality due to scattering of the developer during transfer. It has been confirmed that it has high image quality, stability over time, and environmental stability that surpasses the two-component developer that is reaching

Further, it was confirmed that the positively chargeable developer of the present invention has a wide selection permissible range for the image forming step and the photosensitive material and can be basically used for both the inorganic type photoreceptor and the organic type photoreceptor.

The detailed mechanism why the positively chargeable developer of the present invention has such excellent image forming properties is not necessarily clear, but the electron-donating or cationic nitrogen-containing polar functional group on the surface of the developer particles is not clear. It is presumed that due to the interaction between the group and titanium oxide having an electron-withdrawing or anionic component, the electric charge is stably generated, exchanged, transferred, and retained particularly in the presence of an electric field. Further, the reason why the transferability is good under high temperature and high humidity even when it contains a component considered to be ionic is not only because the macroscopic electrical resistivity of the developer is high, but also because the charge exchange on the surface of the developer particles is stable and stable. It is considered that it is uniform and it is difficult to generate a local high electric field at the time of transfer, and charge injection from the material to be transferred such as paper is blocked.

Hereinafter, the configuration of the present invention will be described in more detail.

First, as a monomer component for introducing a nitrogen-containing polar functional group into the binder resin, N-methylaminoethyl acrylate, N-ethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N- Diethylaminoethyl acrylate, N, N-dibutylaminoethyl acrylate, N, N-diethylaminopropyl acrylate and other substituted amino group-containing acrylates, aminoethyl methacrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N
-Methylaminoethyl methacrylate, N-ethylaminoethyl methacrylate, 2-N, N-dicyclohexylaminoethyl methacrylate, N, N-dibutylaminoethyl methacrylate, 2-phenylaminoethyl methacrylate, 2-dibenzylaminoethyl methacrylate, etc. Amino group-containing methacrylates, aminostyrenes such as aminostyrene, dimethylaminoethylstyrene, N-methylaminoethylstyrene, dimethylaminoethoxystyrene, allylamines such as allylamine and allylmethylamine, N-vinylpyridine, 2-vinyl- Vinyl pyridines such as 5-methyl pyridine, vinyl amines, vinyl quinolines and allyl quinolines, acrylamides, N-vinyl amides and the like can be used.

These monomers are polymerized and used as a homopolymer, or styrenes, methacrylates, acrylates, which are usually used as a monomer component of a binder resin for a developer,
It is possible to introduce a nitrogen-containing polar functional group into the binder resin by copolymerizing with a vinyl monomer such as a diene. Further, a resin having a nitrogen-containing polar functional group such as polyamide, polyamine, polyurethane or polyurea may be used as a part of the binder resin.

Furthermore, a nitrogen-containing polar functional group such as a substituted amino group is introduced into a polymer side chain or terminal by utilizing a chemical reaction such as a polymer reaction, or a substituted amino group such as a polymer side chain or terminal is further substituted. The group may be subjected to a treatment such as quaternary ammonium chloride treatment or betaine treatment.

The nitrogen-containing polar functional group thus introduced into the binder resin, particularly the functional group rich in electron donor property or cationic property such as substituted amino group, has a generally good charge in the coexistence with the electron acceptor property or anionic component. It exhibits exchangeability,
In order to satisfy all the various physical and chemical requirements from all steps of image formation as a developer, a binder containing a substituted amino group-containing methacrylate represented by the following general formula (A) as a monomer component Use of resin is desirable.

General formula (A) In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ and R ₃ may be the same or different and represent a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃ At least one of them is a lower alkyl group, and n is an integer of 1 to 4.

The glass transition temperature of the monomer represented by the general formula (A) is about 40 to 70 ° C. with that of a monomer such as styrene, vinyltoluene, n-butylmethacrylate, and methylmethacrylate which is usually used as a binder resin component. It is desirable to copolymerize and use. Although it cannot be simply specified because it depends on the usage form, if the composition is adjusted so that the amine value is about 5 to 80, preferably about 10 to 50, the electrical characteristics of the developer tend to be stable. The nitrogen-containing polar functional group must be present on the surface of the developer particles together with the electroattractive or anionic component (C). In order to selectively expose the nitrogen-containing polar functional group such as a substituted amino group to the surface of the developer, it is desirable to control the functional group so that it is easily located at the end of the molecular chain or adjust the molecular weight distribution.

Therefore, it is effective to control the number average molecular weight of the binder resin containing the monomer component represented by the general formula (A) to 30,000 or less, more preferably 2,000 to 10,000, in which entanglement of molecular chains does not easily occur. Is. As the binder resin, in addition to the binder resin component containing the nitrogen-containing polar functional group, styrene resin, acrylic resin, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, ethylene / vinyl acetate copolymer, chlorinated polyethylene. Such as olefin resin, epoxy resin, polyester, polycarbonate, polyamide, polyurethane, silicone resin,
Fluorine-containing resins, diene resins such as butadiene and isoprene, petroleum resins, phenol resins, rosin-modified resins, etc.
One or more kinds of synthetic and natural resins which are usually used as the developer binder resin may be mixed. The mixed form may be a state in which the polymer blend is chemically bound such as outer graft copolymerization. Further, according to the requirements of the image forming process such as development and fixing, each of these binder resin components is crystalline / amorphous, linear / non-linear (branching, crosslinking, mutual penetration, etc.), homopolymer / copolymer. A physical structure such as a combination (random, alternating, block graft, etc.) may be selected and used together with a chemical structure. In addition,
When various binder resin components are used in combination, the binder resin component containing a nitrogen-containing polar functional group is 10% by weight or more in all binder resin components,
It is preferable to adjust the content to 40% by weight or more before use.

Examples of the electron-withdrawing or anionic component (C) include acidic --OH group, --COOH group, --SO ₃ H group, or organic or inorganic salt functional group thereof, other derivative group, or --Cl,
Organic compounds having halogen groups such as -F, fine polymer powder, metal oxides and other inorganic compounds, especially 1 μm
Hereafter, a fine powder of preferably 100 mμ or less can be used. Typical examples that can be effectively used are inorganic fine powders such as finely powdered silica, titanium oxide, and carbon black having a pH value of less than 7, preferably a pH value of 5 or less. Titanium oxide having a small electron-withdrawing property or anionic component is preferably used.

Since the titanium oxide fine particles have an electric resistance value of 10 ^{6 to} 10 ⁹ Ωcm, it is easy to set the electric resistance value of the entire developer particles to 10 ¹⁴ Ωcm or more, as compared with carbon black. In addition, since the electric resistance value is lower than that of silica and the negative charge amount of the fine particles themselves is small, the charge amount of the positively chargeable developer composition is less likely to decrease and the durability is improved.

In many cases, the surface of these fine powders has a hydrophilic surface, and in order to improve the humidity dependency, it is generally made lipophilic and hydrophobized, but these treatments are not always necessary in the present invention. In particular, in the case of fine powder having an apparently high electrical resistivity, when the powder has an appropriate hydrophilic surface, the charge exchange of the toner is good and the toner tends to be more stable to the environment.

Incidentally, in order to further impart an electron-withdrawing or anionic functional group to the surface of these fine powders, various coupling agents having these functional group components, metal-containing dyes and other anionic compounds may be treated.

Titanium oxide having an electron-withdrawing or anionic component (C) exists as a discontinuous layer in at least the outermost surface layer portion of the insulating particles (B) together with the nitrogen-containing polar functional group in the insulating particles (B). Need to be

Therefore, titanium oxide having an electron-withdrawing or anionic component (C) may be added inside the insulating particles (B), but after the insulating particles (B) are further prepared, the component (C ) Is added and mixed to the surface of the insulating particles (B),
The method of attaching or fixing (C) is very effective. However, it is desirable that the component (C) is a discontinuous layer in order to maintain the electric resistance of the developer in an insulating region of 10 ¹⁴ Ωcm or more and to ensure good charge exchange.

Therefore, when the component (C) is added to and mixed with the surface of the insulating particles (B) and attached, the insulating particles (B) and the component (C)
It is difficult to unconditionally specify the particle size, shape, specific gravity, etc. of the component, but the component (C) is approximately 0.1% relative to the insulating particle (B).
It is preferable that the discontinuous layer of (C) is formed on the surface of (B) by adding up to 2.0% by weight and mixing with a high speed stirring type mixer or a V type blender.

For example, the insulating particles (B) have a particle size of 15 μm and a specific gravity of 1.1,
When the component (C) is a silica powder having a particle size of 20 mμ and a specific gravity of 2.2, the optimum addition amount of (C) to the (B) is about 0.3% by weight.
To about 1.2% by weight. If necessary, the component (C) may be fixed to the surface of the insulating particles (B) by means of hot air or the like.

When the positively chargeable developer of the present invention is used as a magnetic one-component developer, the binder resin of the insulating particles (B) contains a metal such as iron, cobalt, nickel and the like, alloys thereof, metal oxides and the like. It is necessary to add magnetic powder. In the case of a magnetic toner, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , cobalt-added iron oxide and ferrite powder such as MnZn ferrite, NiZn ferrite and Zn ferrite are usually used.

It is possible to select either granular powder or acicular powder for these magnetic powders, depending on the application.
It is easy to use granular magnetic powder having a size of about μm, particularly preferably about 0.1 μm to 1 μm. These magnetic powders may contain a surfactant, a long chain fatty acid and its derivative, a silane coupling agent, a titanate coupling agent, or
Surface treatment with oligomers, polymers, etc. having polar functional groups such as COOH groups, -OH groups, -NH ₂ groups, or by polymerizing the surface of the magnetic powder to cover the magnetic surface with polymer components. After that, it may be added to and mixed with the binder resin.

The content of the magnetic substance powder in the insulating particles (B) varies depending on the developing method or the specific gravity of the magnetic substance powder, but it is preferable to use it in the range of 15 to 70% by weight with respect to the binder resin. . Especially when used in the range of 40 to 60% by weight, the objects and advantages of the present invention are easily exhibited.

Inside the insulating particles (B), various additives such as colorants may be included. As the colorant, various conventionally known carbon black, magenta, yellow and cyan pigments, nigrosine, fast blue and other various dyes can be used. Further, a surfactant, a quaternary ammonium salt, a charge control agent such as a metal-containing dye having an organic complex structure,
It may also include plasticizers, particulate or organic and inorganic fillers on fibers, blowing agents, antioxidants and the like.

In addition to the component (C), the surface of the insulating particles (B) is used for the purpose of further improving the fluidity of the developer, the storage stability, etc., or the filming of the toner on the photosensitive material. Other external additives may be further added for the purpose of prevention and improvement of toner cleaning property. This external additive is a long-chain fatty acid such as stearic acid and its ester, amide, metal salt, molybdenum disulfide, carbon black, graphite, fluorinated graphite, silicon carbide, boron nitride, silica, aluminum oxide, titanium dioxide. , Fine powder such as zinc oxide, fine powder such as fluorine-based resin, polycyclic aromatic compound, wax-like substance, crosslinked or non-crosslinked resin fine powder, it is not necessarily limited, usually, the critical surface tension 30 dyn / cm These are solid fine particles having the following low surface energy or having a smooth surface with a friction coefficient of 0.1 or less, or fine particles having non-adhesiveness and slight polishing property. If necessary, a treatment of fixing these external additives to the surface of the toner particles with hot air or the like may be performed.

In the case of producing the positively chargeable developer composition of the present invention, a binder resin, other additives and the like are melt-kneaded and then pulverized, a spray dry method, a suspension polymerization or an emulsion polymerization reaction is used. Any manufacturing method such as a method of manufacturing by direct polymerization can be basically used.

However, no matter what manufacturing method is adopted, manufacturing conditions are such that the nitrogen-containing polar functional group of the binder resin and the electron-withdrawing or anionic component are discontinuously and uniformly dispersed on the surface of the developer particles. It is important to choose.

It is desired that the particle size of the developer particles is adjusted to 1 to 50 μm, preferably about 5 to 20 μm. Therefore, if necessary, the particle size is adjusted by classification.

In the present invention, the electrical resistivity of the developer was measured by the following measuring method. The developer particles are sandwiched between electrodes having a guard electrode with a diameter of 50 mm, a load of 200 g / cm ² is applied, the distance between the electrodes, that is, the developer particle layer thickness is adjusted to about 1 mm, and a DC voltage of 100 V to 1000 V is sequentially applied. Apply. The current value was read 1 minute after each voltage was applied, and then static electricity was removed for 1 minute, then voltage was applied again and the same operation was repeated. The current value thus obtained for each applied voltage was converted into a volume resistivity plot and the electrical resistivity at an electric field of about 10 ⁴ V / cm was taken as the electrical resistivity of the developer.

The positively chargeable developer of the present invention sufficiently exhibits its characteristics when used as a one-component developer that does not use carrier particles, and offers advantages over conventional one-component and two-component developers. However, the developer of the present invention can be used as a toner or a carrier of a two-component developer, and a two-component developer having good charging characteristics can be obtained.

Further, when used as a one-component developer, it is easier to use magnetic toner by mixing magnetic powder in developer particles as described above, but of course even when image formation is performed as non-magnetic toner, The effects of the invention are fully achieved. Further, in the case of magnetic toner, it is possible to develop a magnetic latent image in addition to the electric latent image.

〔Example〕

Hereinafter, the present invention will be described with reference to Reference Examples, Examples, and Comparative Examples, but of course the present invention is not limited to these Examples. In the following examples, parts represent parts by weight.

Comparative Example 1 Styrene resin (number average molecular weight 4000) 40 parts Styrene / n-butylmethacrylate copolymer (styrene = 60%, number average molecular weight 40,000) 50 parts Ferrous tetraoxide (particle size = 0.3 μm, granular powder) 100 Part was melt-kneaded with a rotor rotary kneader, cooled, pulverized, and further classified to adjust the average particle size to 13.8 μm, to obtain a toner (a).

Then, fine silica powder (particle size 16 mμ, pH =
Toner (b) was prepared by adding 0.6% by weight of 4) and mixing with a high-speed stirring mixer.

Reference Example 1 The styrene resin of Comparative Example 1 was changed to a diethylaminoethylmethacrylate-styrene copolymer (diethylaminoethylmethacrylate component 7 mol%, number average molecular weight 4000, amine value = 30), and the average particle size was changed according to the completely same formulation. A 13.5 μm toner (C) was prepared. Toner (d) was prepared by adding 0.6% by weight of the same silica fine powder as in Comparative Example 1 to this toner and mixing.

Toners (a), (b) of Comparative Example 1 and Reference Example 1,
Typical characteristics of (c) and (d) and manufactured by Fuji Zerox Co., Ltd.
The table below summarizes the image characteristics evaluated by a copier that was modified from the FX-2830 copier and incorporated an organic photoreceptor and a one-component developing machine.

As can be seen from the table, the toner (d) of the reference example shows very good image characteristics, from a low temperature and low humidity environment of 10 ° C and 15% humidity to a high temperature and high humidity environment of 30 ° C and 85% humidity. The image quality was extremely stable against changes in the environment.

In addition, even after continuous copying of 50,000 sheets, the image quality was always clear, and there was no change over time or deterioration of the developer.

The toner (c) to which the acidic silica powder is not added is also better than the toners (a) and (b), but is inferior to the toner (d).

The presence of N atoms was confirmed by ESCA on the surfaces of the toners (c) and (d), and it was confirmed that diethylamino groups were effectively present on the toner surfaces. Also, the toner (b),
(D) It was confirmed by electron microscope observation that the silica powder adhered to the surface of the toner particles very uniformly and discontinuously.

Comparative Example 2 To the composition of Comparative Example 1, 2 parts of Nigrosine dye was further added,
Kneading, pulverizing and classifying with the same formulation, average particle size 13.4μ
m, and the electric resistance was 3.9 × 10 ¹⁵ Ωcm. The image quality of this toner was evaluated in the same manner as in Comparative Example 1, but as in Comparative Example 1, the image quality was inferior.

Further, the image quality of the toner obtained by further adding 0.6% by weight of silica powder to the toner and mixing the toner was not excellent.

Reference Example 2 Styrene / n-butyl methacrylate / diethylaminoethyl methacrylate copolymer (composition ratio is 65/35/5,
Number average molecular weight 28,000, amine value = 20) 90 parts 100 parts of ferric tetroxide (particle size = 0.3 μm, granular powder) was kneaded, then pulverized and classified to obtain a toner having an average particle size of 14.1 μm. Further silica powder (pH = 4, particle size = 12mμ)
0.8 wt% was added and mixed, and the electric resistivity was adjusted to 5.0 × 10 ¹⁵ Ωcm. When the image quality of this toner was evaluated in the same manner as in Example 1, a very detailed image quality was obtained. It was also very stable against repeated copying of 50,000 sheets and environmental changes from high temperature and high humidity to low temperature and low humidity.

Reference Example 3 FX-2300 with the toner (d) of Reference Example 1 incorporated into a ZnO photoreceptor
When the image quality was evaluated with a modified copying machine in the same manner as in Reference Example 1, an image as good as or better than that in Reference Example 1 was obtained. The environment and stability over time were also good.

Example 1 Styrene / dimethylaminoethyl methacrylate copolymer (styrene 97%, amine value = 17, number average molecular weight 2,90)
0) 28 parts Styrene / butadiene cross-linked copolymer (gel fraction 90%)
20 parts Polypropylene wax 2 parts Ferrous tetroxide (particle size 0.5 μm) 50 parts were kneaded, ground and classified in the same manner as in Reference Example 1 to obtain an average particle size of 12.7.
μm toner was obtained. Furthermore, silica powder (particle size = 16 mμ, p
H = 4) 0.6% by weight and titanium oxide powder (particle size = 30 mμ, p
H = 3) 0.4% by weight is added and mixed, and the electrical resistivity is 5.8 × 10 ¹⁵
Ωcm toner particles were prepared. The image quality of this toner was evaluated in the same manner as in Reference Example 1, but extremely excellent image characteristics were confirmed. There were no problems in environmental stability and temporal stability.

Example 2 Styrene / dimethylaminoethyl methacrylate (95% styrene, amine value = 25, number average molecular weight 6,100) 50 parts Hydrogenated styrene / isoprene block copolymer 12 parts Polyethylene wax 23 parts Iron trioxide 90 parts Kneading, crushing and classification were carried out in the same manner as in Reference Example 1, with an average particle size of 15.2.
μm toner was obtained. To this toner, 0.4% by weight of carbon black (pH = 3, particle size 24 mμ) and 0.3% by weight of titanium oxide of Example 4 were added and mixed, and the electric resistivity was 8.9 × 10 ¹⁴ Ω.
Adjusted to cm.

When the image quality of this toner was evaluated in the same manner as in Reference Example 3, a good image was obtained as in Example 1.

The pressure fixing was performed with a metal roll having a linear pressure of 20 kg / cm, but the fixing property was also very good.

〔The invention's effect〕

The positively chargeable developer composition of the present invention is excellent not only as a two-component developer that uses carrier particles but also as a one-component developer that does not use a carrier, and has excellent chargeability and developability, as well as developability and transferability. Excellent, charging, development, transferability is stable against environmental changes such as temperature and humidity, characteristics do not change even after repeated use, no change over time, deterioration is not seen, It has the features that a stable image can be formed regardless of the image forming process and that it has excellent developability and transferability regardless of whether it is an organic or inorganic photosensitive material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Fujii 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Zero Tsux Co., Ltd. Takematsu Plant (72) Inventor Hiroaki Yoshikawa 1600 Takematsu, Minamiashigara, Kanagawa Fuji Zero Tux Co., Ltd. Takematsu Business In-house (72) Ken Inagawa, 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Zero Tux Co., Ltd., Takematsu Works (72) Inventor, Masayuki Torikoshi 1600 Takematsu, Minami Ashigara-shi, Kanagawa Fuji Zero Tux Co., Ltd., Takematsu Works (56) Reference Documents JP-A-59-187348 (JP, A) JP-A-58-17454 (JP, A) JP-A-57-130047 (JP, A) JP-A-55-18658 (JP, A) JP-A-61- 91669 (JP, A) JP 61-91670 (JP, A)

Claims (2)

[Claims] 1. A titanium oxide containing an electron-withdrawing or anionic component is present on at least the surface layer of insulating particles containing a binder resin containing a monomer component having a nitrogen-containing polar functional group as an essential component. A positively chargeable developer composition, characterized in that a continuous layer is formed and the electric resistivity of the whole developer particles is adjusted to 10 ¹⁴ Ωcm or more. 2. A monomer component having a nitrogen-containing polar functional group is represented by the following general formula: [In the formula, R ₁ is a hydrogen atom or a methyl group, and R ₂ and R _{3 are}
May be the same or different and are a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, but R ₂ and R ₃ do not represent a hydrogen atom at the same time, and n is an integer of 1 to 4. . ] The positively chargeable developer composition according to claim 1, which is a compound represented by the formula [1].