JPH0812465B2 - Positively charged developer - Google Patents

Description

The present invention relates to a positively chargeable developer used in electrophotography, electrostatic printing and the like. More specifically, the present invention relates to a positively charged toner, a positively charged silicic acid fine powder, and a positively charged developer containing fine particles of a fluorine-containing resin.

[Conventional technology]

Conventionally, methods such as a cascade method and a powder cloud method are also known as methods for developing non-magnetic toner in electrophotography, but in general, in order to efficiently convey non-magnetic toner to a developing unit, iron powder and ferrite are used. A method of mixing with magnetic particles such as powder is adopted.

As one example, mixing toner and magnetic particles,
A method of forming a magnetic brush and rubbing and developing an electrostatic charge image is widely known.

As still another developing method, a developer container that stores toner and magnetic particles for toner application, a toner carrier that conveys toner to a latent image carrier, and the toner carrier on the upstream side of the toner outlet of the developer container. A thin layer of toner is formed on the toner carrier by arranging a magnet that forms a magnetic brush made of magnetic particles for toner application that comes into contact with the body, and the toner carrier and the electrostatic image holding are more than the toner layer thickness. There is a method of developing an electrostatic image by setting a large gap with the body.

These methods require that a substantially non-magnetic toner be kept in a uniformly mixed state with magnetic particles in a developing section or in a uniformly thin layer coated state on a carrier, and yet that state is achieved. The electrostatic attraction and the physical adhesive force are mainly dominant as the force to perform. That is, it is necessary to precisely control the amount of electrostatic charge and the triboelectric charging ability of the toner. In particular, it is a well-known fact that various types of positive charge controllability and positively chargeable resins are searched for precise control of the chargeability of positively chargeable toner. Among them, in particular, a positively chargeable resin that is uniformly and strongly positively charged, and is itself colorless, is expected to be a positively chargeable resin applicable to color toners.

However, conventionally known positively chargeable resins can retain a considerably large positive charge, but are known to be difficult to be charged unless they undergo firm friction, that is, the so-called triboelectric charging rises slowly. . Further, a resin generally contains a polar group in order to have a positive charge, but the polar group often contains an element such as nitrogen or phosphorus and has a hygroscopic property.

For this reason, it is quite difficult to control the charge amount of the toner uniformly, and to stabilize the charge amount even after repeated copying over a long period of time or under the special environment of high temperature / high humidity / low temperature / low humidity. It is accompanied. Particularly in the case of positively chargeable toner, resin, which is a component of the toner,
It is very difficult to uniformly positively charge the pigment, the fluidizing agent, the abrasive, the lubricant, etc., and it is not clear how the material composition relating to the charging as a positively charging toner should be.

From the above, the positively chargeable resin may cause a considerable difference in the triboelectric charge amount and the rising of the charge in a special environment such as high temperature high humidity, low temperature low humidity, etc. This is one of the reasons why it is difficult to use the positively chargeable resin as a binder for toner because it leads to a density loss.

[Problems to be solved by the invention]

An object of the present invention is to provide a positively chargeable developer that solves the above problems.

That is, an object of the present invention is to provide a positively chargeable developer having an ideal material structure as a positively chargeable developer and exhibiting stable triboelectrification properties even after long-term use or under a special environment of high temperature / high humidity / low temperature / low humidity. To provide a positive developer.

[Means and Actions for Solving Problems] The present invention provides a copolymer containing at least 2 to 15% by weight of an aminoacrylic component as a constituent in all binder resins.
Positively chargeable development containing 100 parts by weight of positively chargeable toner containing 30% by weight or more, 0.01 to 3 parts by weight of positively chargeable silicic acid fine powder, and 0.1 to 5 parts by weight of fine particles of negatively chargeable fluororesin. And a triboelectric charge amount T _A of the positively chargeable toner is T _A ≧ + 20 μC / g, and a mixture of the positively chargeable toner, the silicic acid fine powder, and the negatively chargeable fluorine-containing resin fine particles is used. When the triboelectric charge amount is T _B , 1.2 ≦ T _A / T _B ≦ 3 is more preferable, and the triboelectric charge amount of positive charge is suppressed so that 1.2 ≦ T _A / T _B ≦ 2, and T _B is
It relates to a positively chargeable developer characterized by being lower than T _A by 6.8 μC / g or more.

The term "toner" as used herein refers to an integrated particle obtained by kneading, pulverizing, classifying, or melting, spraying (dispersing) granulating, or polymerizing granulating raw materials, and then fluidizing agent and charge controlling agent. It is different from the form of the developer having an external additive that is put into practical use by mixing particles with.

The present inventor diligently studied the stability of triboelectrification after a long-time copying of a positively chargeable developer having a positively chargeable toner and in a special environment of high temperature / high humidity / low temperature / low humidity. The fluctuation of the triboelectrification property of the developer under special circumstances may be affected by the qualitative and quantitative fluctuations of the particles externally added as the fluidity improver / charge control agent, rather than the toner matrix itself. Was found to be high. However, downsizing and easy handling of copiers
In these days when technology such as long life is required, improvement of the fluidity of the developer is essential for simplifying the developing device, and for that reason, there is no choice but to rely on an external additive to some extent. In consideration of such a situation, as a result of studying a developer composition having good fluidity and stable chargeability even under special circumstances, 1) the toner base has a large chargeability.

2) Addition of the fluidity-improving agent should reduce the chargeability of the toner by a specific amount as shown in Examples below.

I found out. Further, as the external additive to the toner such as a fluidity improver, it is more preferable to use at least two kinds of positively chargeable ones, that is, positively chargeable silicic acid fine powder and negatively chargeable ones, namely fluorine-containing resin fine particles. He found that it stabilizes sex.

Although the details are not clear, it is presumed that the positively chargeable particles and the negatively chargeable particles are well balanced and do not disturb the chargeability of the toner base.

As fine particles to be added externally, positively chargeable silicic acid fine powder is used as the positively chargeable particles, considering that it has high fluidity control ability and does not have usual environmental instability such as moisture absorption at high temperature. As the negatively chargeable particles, fluorine-containing resin fine particles are most preferable.

In particular, in the present invention, the negatively chargeable fluorine-containing resin particles are considered to exhibit a microcarrier-like behavior that gives positive tribocharge to the positively chargeable developer, and the triboride as a developer is considered. Even in ultra-long-term durability under high humidity, which shows a tendency to decrease, the durability was remarkably excellent as compared with the case where no fluorine-containing resin particles were added.

The copolymer containing an aminoacrylic component used in the present invention contains 30% by weight or more, and more preferably 50% by weight or more in the toner in order to surely exhibit its performance and have a positive positive charge. Preferably.

Further, as the amino acrylic monomer as a constituent of the copolymer containing an amino acrylic component used in the present invention, all the conventionally known ones can be used, but generally, those represented by the following structural formula are It is valid.

R ₁ is hydrogen or a methyl group or an ethyl group R ₂ is an alkylene group having 1 to 4 carbon atoms R ₃ and R ₄ are alkyl groups having 1 to ₄ carbon atoms Among them, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylamino Ethyl methacrylate and diethylaminoethyl methacrylate are preferred. Further, as the constituents other than the aminoacryl of the present invention, all the conventionally known monomers can be used, but in general, vinyl monomers, particularly styrene-
It is desirable to contain an acrylic comonomer in an amount of 70% by weight or more. Examples of the styrene-based monomer include styrene, vinyltoluene, α-methylstyrene, and the like, and examples of the acrylic-based monomer include acrylic acid, esters of methyl, ethyl, propyl, butyl, and 2-ethylhexyl of acrylic acid, Methacrylic acid, methyl, ethyl, propyl, butyl, and 2-ethylhexyl esters of methacrylic acid may be mentioned, respectively.

In the present invention, as a method for polymerizing the copolymer, a conventionally known method can be used, but a homogeneous system such as bulk polymerization or solution polymerization is particularly preferable.

As the fluorine-containing resin constituting the negatively chargeable fluorine-containing resin fine particles used in the present invention, all conventionally known ones can be used, but vinylidene fluoride, tetrafluoroethylene, trifluoroethylene chloride are preferable. Polymers or copolymers of propylene hexafluoride, hexafluoroisopropyl methacrylate and the like are preferable, and vinylidene porphyride and ethylene tetrafluorofluoride are more preferable.

It is desirable that the negatively chargeable fluorine-containing resin fine particles have an average particle size of 5 μm or less, preferably 2 μm or less, in order to sufficiently exhibit the ability when mixed with the positively chargeable toner. In addition, the mixing ratio is a weight ratio of positively charged toner / negatively charged fluororesin resin fine particles = 100 / 0.1 to 100
/ 5, more preferably 100 / 0.2 to 100/3 is desirable. As the mixing method, a device having a shearing force such as a conventionally known Hensiel mixer, a tumbler blender,
Any device such as a ball mill that does not have a shearing force or a Nauter mixer may be used.

As the positively charged silicic acid fine powder used in the present invention,
Although the one in which the variation of the triboelectric charge amount due to the mixing with the toner satisfies the above condition is used, it is preferable that the charge of the positively chargeable toner is not disturbed. For example, a coupling treatment with an aminoalkylsilane compound or an amine on the side chain A fine silicic acid powder treated with a silicone oil having a is preferred, and a silicic acid fine powder treated with a silicone oil having an amine in a side chain is most preferable from the viewpoint of environmental stability. As the matrix of the fine silicic acid powder, fine silicic acid powder manufactured by a dry method or a wet method can be used.

The dry method here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halogen compound.
For example, in a method utilizing a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl In this manufacturing process, for example, by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound, a fine composite powder of silicic acid and another metal oxide. It is also possible to obtain and include them.

Examples of commercially available silicic acid fine powders produced by vapor phase oxidation of a silicon halogen compound used in the present invention include those commercially available under the following trade names.

AEROSIL 130 (Nippon Aerosil) 200 300 380 OX50 TT600 MOX80 MOX170 COK84 Ca-O-SiL M-5 (CABOT Co.) MS-7 NS-75 HS-5 EH-5 Wacker HDK N 20 V15 (WACKER-CHEMIE) GMBH) N20E T30 T40 D-C Fine Silica (Dow Corning Co.) Fransol (Fransil) On the other hand, the method for producing the silicic acid fine powder used in the present invention by a wet method is various conventionally known methods. Can be applied. For example, if sodium silicate is decomposed by an acid, and if it is shown by a general reaction formula (the following reaction formula is abbreviated), Na ₂ O ・ XSiO ₂ + HCl + H ₂ O → SiO ₂・ nH ₂ O + NaCl, other ammonium salts of sodium silicate or alkali Decomposition by salts, method of generating alkaline earth metal silicate from sodium silicate, then decomposing with acid to silicic acid, method of converting sodium silicate solution into silicic acid by ion exchange resin, natural silicic acid or There is a method of using silicate.

As the silicic acid fine powder referred to herein, anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate and zinc silicate can be applied.

Examples of commercially available silicic acid fine powders synthesized by the wet method include those commercially available under the following trade names.

Carpretx Shionogi Nepseal Nippon Silica Tokseal, Huainseal Tokuyama Soda Vita Seal Taki Manure Shilton, Shirunetsu Mizusawa Chemical Starsil Kamijima Chemical Himedir Ehime Pharmaceutical Syloid Fuji Debison Chemical Hi-Sil (High Seal) Pittsburgh Plate Glass.Co. (Pittsburgh Silver Plate) Fiillstoff-Gesellschaft Ultorasil (Ultraseal) Marquart (Manufacture) Manosil (Manosir) Hardman and Holden (Hoesch) Chemische Fabrik Hoesch K-G Sil-Stone Stoner Rubber Co. Nalco Nalco Chem.Co. Quso Quaxz Philadelphia Quartz Co. Delphi Quartz Imsil Illinois Minerals Co. Calcium Silikat Chemische
Fabrik Hoesch.K-G
Calsil Fiillstoff-Gesellschaft Marquart Fortafil Imperial Chemical Industries.Ltd. (Imperial)
Chemical Industries Microcal Joseph Crosfiels & Sones. Ltd. Manosil Hardman and Holden Vulkasil Farbenfabriken Bryer, A.-G. Breeken Bayer) Tufknit Durham Chemicals. Ltd. Sirimos Shiraishi Kogyo Starletx Kamishima Chemical Precosyl Polywood Manure Of the above silica fine powder, the specific surface area by nitrogen adsorption measured by BET method is 30m ² Those in the range of / g or more (particularly 50 to 400 m ² / g) give good results.

As the silicone oil having an amine in the side chain used for the treatment of the silicic acid fine powder, a silicone oil containing a structural unit represented by the formula (I) can be generally used.

(Here, R ₁ represents hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ and R ₄ represent hydrogen, an alkyl group or an aryl group. The alkyl group, aryl group, alkylene group, and phenylene group may contain an amine, and may have a substituent such as halogen within a range not impairing the charging property.) A commercially available side chain The amine-containing silicone oil is preferably an amino-modified silicone oil represented by the following structural formula. that is (Here, R ₁ and R ₅ represent an alkyl group and an aryl group,
R ₂ represents an alkylene group, a phenylene group or an alkyl group containing an amine, and R ₃ represents hydrogen, an alkyl group or an aryl group. m and n are numbers of 1 or more. ) The silicone oils represented by the following are specifically preferable, and these may be used in one kind or in a mixed system of two or more kinds.

The amine equivalent is the equivalent per amine (g / eq
In iv), the molecular weight is divided by the number of amines per molecule.

The amount of the silicone oil having an amine in the side chain in the present invention is 0.2 to 70% of the total amount of the treated silicic acid fine powder.
It is preferable that the weight percent is 0.0001 to 10 weight percent in the developer. Further, the proper treatment amount of the silicone oil having an amine in the side chain is such that the weight part of the silicone oil is x with respect to 100 parts by weight of the fine silica powder before the treatment with the silicone oil. If the specific surface area of the fine powder is bm ² / g and the amine equivalent of the silicone oil having amine in the side chain is a,
When the relation of formula (II) is satisfied, particularly good results are given.

In the above formula, In the case of, the silicone oil having an amine in the side chain is in a large excess relative to the silicic acid fine powder, which may cause a problem such as leaching of the silicone oil having an amine in the side chain from the silicic acid fine powder. . Also, In this case, the chargeability is insufficient and it becomes difficult to achieve the object of the present invention.

On the other hand, 25 ° C of silicone oil having amine in the side chain
The viscosity is preferably 5000 cps or less, and particularly preferably 3000 cps or less. When the viscosity is 5000 cps or more, the silicone oil having an amine in the side chain is insufficiently dispersed in the silicic acid fine powder, which easily causes a defective image such as fog.

The above-mentioned treatment with the silicone oil having an amine in the side chain of the silicic acid fine powder can be performed, for example, as follows. The silicic acid fine powder is violently agitated while being heated if necessary, and a silicone oil having an amine in the side chain or a solution thereof is sprayed or vaporized and sprayed on the silicic acid fine powder, or a silicic acid fine powder is slurried. It can be easily treated by adding a silicone oil having an amine to a side chain or a solution thereof while stirring the mixture.

In the present invention, one kind or a mixture of two or more kinds of the above-mentioned silicone oil having an amine in the side chain may be used.

Also, the applied amount of these treated silica fine powders is
The triboelectric charge amount of positively charged toner is reduced by 6.8 μC / g or more and the ratio of triboelectric charge amount is T _A / T _B
May be set so as to satisfy the above conditions, but generally 0.01 to 3 parts by weight with respect to 100 parts by weight of the positively chargeable toner, the effect is exhibited, and particularly preferably 0.03 to 1.5 parts by weight is added. In particular, it exhibits positive chargeability with excellent stability.

Further, the powder having a volume average secondary particle diameter of 0.5 to 3 μm is preferably used.

Further, the positively-charged silicic acid fine powder used in the present invention may be further treated with a conventionally known hydrophobizing agent, if necessary, and a known method may be used as the silicic acid fine powder. It is provided by chemically treating with an organic silicon compound that reacts or physically adsorbs.

Examples of such organosilicon compounds include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule There is dimethylpolysiloxane having a Si-bonded hydroxyl group for each unit located at the terminal. These are used alone or as a mixture of two or more.

In the present invention, it is possible to add other resins, polymers and the like to the toner in addition to the above copolymers. Examples thereof include polystyrene, styrene-butadiene copolymer,
Styrene-based copolymers such as styrene-acrylic copolymer,
Polyethylene, polyethylene-vinyl acetate copolymer, ethylene-based copolymer such as polyethylene-vinyl alcohol copolymer, phenol-based resin, epoxy-based resin, allyl phthalate resin, polyamide resin, polyester resin, maleic acid-based resin, etc. is there. In addition, the manufacturing method and the like of each resin is not particularly limited.

As the coloring material used for the positively chargeable toner, conventionally known coloring materials such as carbon black, dyes and pigments can be used. Usually, 0.1 to 15% by weight is used with respect to 100 parts by weight of the binder resin.

It is also possible to add other lubricants, abrasives, etc. internally or externally to the positively charged toner.

It is also possible to implement the above-mentioned constitution in the microcapsule toner by using the core material, the shell material, or both of them.

Further, as the carrier and magnetic particles to be mixed with the toner of the present invention, all conventionally known ones can be used,
Since the positively chargeable resin has a considerably large positive charge and tends to be strengthened by the fluorine-containing resin fine particles, it is preferable to use a resin in the direction of suppressing the charging of the toner. Specifically, toner is charged on the surface of fine particles having an average particle size of 20 to 300 μm, such as surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, and rare earths, and alloys or oxides thereof. A substance to suppress against magnetic fine particles,
Those treated about 0.1 to 20% by weight are preferable. The treatment substance may be arbitrarily determined depending on the toner form, but generally, a silicone resin, a polyester resin, a styrene resin, an acrylic resin, polyvinyl butyral, nigrosine, an aminoacrylate-containing resin or the like is used alone or as a fluorine-containing resin. It is used as a mixture, and among them, a silicone resin, a styrene resin, or a mixture of a styrene resin and a fluorine-containing resin is particularly preferable.

Next, a method of measuring the triboelectric charge amount in the present invention will be described.

 FIG. 3 is an explanatory diagram of a triboelectric charge amount measuring device.

Toner or fine particles of toner composition for measuring the triboelectric charge amount in a metal measuring container 12 having a conductive screen 13 of 400 mesh (the size can be appropriately changed so that magnetic particles do not pass) at the bottom, and 200 to 300 Weight ratio of irregularly shaped iron powder with particle size between meshes (EFV200 / 300 made by Nippon Iron Powder, the surface is untreated and, like the toner carrier, has virtually no triboelectricity of its own)
Approximately 4 g of a 1: 9 mixture (developer) is put and a metal lid 14 is placed. At this time, the total weight of the measurement container 2 is weighed and set as W ₁ (g). Next, in the suction device 11 (at least the portion in contact with the measurement container 2 is an insulator), suction is performed from the suction port 17 and the air flow rate control valve 16 is adjusted to bring the pressure of the vacuum gauge 15 to 70 mmHg. In this state, suction is sufficiently performed (for about 1 minute) to remove the toner or the mixture of the toner and the fine powder of silicic acid by suction. The potential of the electrometer 19 at this time is V (volt). Here, 18 is a capacitor, and the capacity is C (μF). In addition, the total weight of the measuring container after suction is weighed and is W ₂ (g). This triboelectric charge amount T (μC / g) is calculated by the following equation.

However, the measurement conditions are 23 ° C and 50% RH.

〔Example〕

Specific examples will be described below. All parts and percentages are by weight.

Example 1 Was copolymerized in a xylene solvent to obtain a positively chargeable resin. next Was melt-kneaded, pulverized and classified to obtain a blue positively charged toner having an average particle diameter of 12 μm. The triboelectric charge amount T _A of the obtained positively chargeable toner was +34.0 μc / g.

On the other hand, 100 parts by weight of fine silica powder (trade name, Aerosil ^# 130, specific surface area of about 130 m ² / g, manufactured by Aerosil Co., Ltd.) synthesized by a dry method is kept at a temperature of about 250 ° C. while stirring to a side chain. Spray 20 parts by weight of amine-containing silicone oil (viscosity 70 cps at 25 ° C, amine equivalent 830) at 10
Processed in minutes.

100 parts by weight of the above blue positively chargeable toner, 0.8 part by weight of positively chargeable silicic acid fine powder treated with the above silicone oil having an amine in the side chain, and negatively chargeable polyvinylidene fluoride fine particles (average particle size of 1 μm or less) ) 0.5 parts by weight were externally mixed with a Henschel mixer.

The resulting triboelectric charge T _B of the mixture + 21.0MyuC a / g, T _B is 13μC / g lower than T _A, was T _A / T _B = 1.62.

Next, 100 parts by weight of iron powder having an average particle size of 80 μm as a carrier was coated with 1.2 parts by weight of polyvinylidene fluoride-methyl methacrylate mixed (1: 1) resin on the surface thereof.

A two-component developer prepared by mixing 4 parts by weight of the above mixture with 100 parts by weight of the above carrier was charged into a Canon copier NP-5000 modified to form a negative electrostatic image, When the image is displayed in the environment of, the image reflection density is 1.45 at 23 ℃, 60% RH, 15 ℃, 10% in all environments.
It was as high as 1.48 at RH and 1.42 at 90% RH at 35 ° C, and it was possible to obtain clear images with fog. In addition, no abnormality was found in the initial images after being left for one month in each environment.

Furthermore, to check the durability of the developer, 23 ℃, 60%
After running 10,000 sheets under the condition of RH, a clear image (image density 1.43) without fog similar to the initial stage was obtained.

Comparative Example 1 When the positively charged toner of Example 1 was externally mixed with 3.5% of the silicic acid fine powder of Example 1, T _B was +9.7 μC / g and T _A / T _B was 3.5. Therefore, the conditions in the present invention were not satisfied.

When the same test as in Example 1 was conducted using this two-component developer, fog was generated as the number of copies increased. Further, under a low temperature and low humidity environment, a clear image was obtained as compared with the case of Example 1.

Comparative Example 2 Styrene-butyl acrylate copolymer (copolymerization ratio 80: 2
0) 95 parts Copper phthalocyanine pigment 5 parts Nigrosine (positive charge control agent) 2 parts Using the above materials, a blue positive charge toner was obtained in the same manner as in Example 1. The triboelectric charge amount T _A of the obtained positively chargeable toner was +11 μC / g. Then positively charged toner 1
00 parts by weight and positively charged silicic acid fine powder prepared in Example 1
0.8 parts by weight was externally mixed.

The triboelectric charge amount T _B of the obtained mixture was +15 μC / g, and
_B was 4 μC / g higher than T _A , and T _B / T _A was about 0.73.

Using this mixture, an image development test was conducted in the same manner as in Example 1. As a result, an image reflection density of 1.33 was initially obtained at 15 ° C. and 10% RH, but 10,000 sheets were durable. As a result, the image reflection density dropped to 1.07. Furthermore, the initial image reflection density was as low as 0.90 at 15 ° C and 10% RH, and the image was thin.

Comparative Example 3. For 100 parts by weight of the positively chargeable toner used in Example 1, 0.8 parts by weight of untreated fine silica powder (Aerosil R972 manufactured by Aerosil Co., Ltd.) and polyvinylidene fluoride fine particles used in Example 1 When 0.5 part by weight was externally added and mixed in the same manner as in Example 1, T _B of the mixture was +6.8 μC / g, and T _B was T _A
It was 27.2 μC / g lower than that and T _A / T _B was 5, which did not satisfy the conditions in the present invention. Using this mixture, a two-component type developer was prepared in the same manner as in Example 1, and the same test as in Example 1 was carried out. As a result, the initial image reflection density was low at 0.97 at 35 ° C. and 90% RH. It was a light image.

Example 2 FIG. 1 is another example of the embodiment. In FIG.
Is an electrostatic image carrier, 2 is a toner carrier, 5 is a one-component toner specified in the present invention, 43 is a developing device, 48 is a magnetic roller, and 49
Is its non-magnetic sleeve, 50 is a magnet, 52 is a magnetic brush, 53
Indicates a one-component toner or a two-component developer in which a toner and a magnetic carrier are mixed. The magnetic carrier is magnetically held on the non-magnetic sleeve 49 to form a brush, and the sleeve 49 is rotated. The toner or developer 53 is scooped up by the carrier brush and applied on the toner carrier 2 in a uniform manner. The toner layer 5 is formed. At that time, since the carrier is held on the magnetic roller 48 by the magnetic force, it does not move onto the toner carrier 2. Next, flight development is carried out from the toner carrier 2 onto the electrostatic image carrier 1. The gap between the magnetic roller 48 and the toner carrier 2 is adjusted so that the thickness of the toner layer on the toner carrier 2 is about 5 to 100 μm. The developing bias voltage may be applied to the toner carrier so that the gap between the toner carrier 2 and the electrostatic image carrier 1 is larger than the toner layer thickness.

here Was copolymerized to obtain a positively chargeable resin.

100 parts by weight of this copolymer and 5 parts by weight of rhodamine pigment are melt-kneaded, jet-ground and classified to obtain an average particle diameter of 11 μm.
To obtain a red positively chargeable toner. The T _A of the positively chargeable toner was +24.0 μC / g.

100 parts of this positively chargeable toner, 1.0 part of the positively chargeable silicic acid fine powder of Example 1 and 1.0 part by weight of negatively chargeable polytetrafluoroethylene fine particles (average particle size 0.3 μm) were mixed. T _B of the mixture + 17.1MyuC a / g, T _B than T _A 6.9μC / g low, T _A / T _B was 1.40.

A two-component developer prepared by mixing 10 parts by weight of this mixture with 100 parts by weight of silicone-coated ferrite particles (average particle size 60 μm), a gap between the toner carrier 2 and the magnetic roller 48, about 2 mm, a magnetic brush. 52 is put into the developing device shown in FIG. 1 which is set to have a maximum thickness of about 3 mm, the gap between the developing roller and the electrostatic image carrier is kept at 300 μm, and a toner layer of about 80 μm is formed on the developing roller. Then, as an AC waveform, a DC component of -250 V was added to a peak value of ± 450 V at a frequency of 200 Hz to give peak values of -700 V and +200 V, and the image was developed on a Canon PC-20. The same good result was obtained.

Example 3 FIG. 2 is a diagram showing another example of the embodiment. In the figure, 1 is an electrostatic image carrier, 2 is a toner carrier, 3 is a hopper, 6 is a developing bias power source, 5 is a one-component toner specified in the present invention, 50 is a fixed magnet, and 52 is a magnetic particle toner mixture. And 58, a toner thickness regulating blade. The magnetic brush 52 formed on the toner carrier 2 is circulated by rotating the toner carrier 2, and the hopper 3
The toner contained therein is taken in and uniformly coated on the toner carrier 2 in a thin layer. Next, the toner carrier 2 and the electrostatic image carrier 1
And are opposed to each other with a gap larger than the toner layer thickness, and the toner 5 on the toner carrier 2 is fly-developed onto the electrostatic image on the electrostatic image carrier 1. The thickness of the toner layer is controlled by the size of the magnetic brush 52, that is, the amount of magnetic particles and the regulating blade 58. The gap between the electrostatic image carrier 1 and the toner carrier 2 may be made larger than the toner layer thickness and a developing bias may be applied from the bias power source 6.

here Was copolymerized to obtain a positively chargeable resin.

60 parts by weight of this positively chargeable resin, 40 parts by weight of styrene-butadiene copolymer (80:20), and 6 parts by weight of an azo red pigment were melt-kneaded, jet-crushed and classified to obtain an average particle diameter of 10 μm.
To obtain a red positively chargeable toner.

The T _A of the obtained red positively chargeable toner was +28.3 μC / g. Using this red positively charged toner, positively charged silicic acid fine powder and negatively charged polyvinylidene fluoride fine particles were mixed in the same manner as in Example 1. The mixture has a T _B of + 21.5μ
A C / g, T _B than T _A 6.8μC / g low, T _A / T _B was 1.31. A two-component developer prepared by previously mixing 20 g of this mixture with 60 g of the ferrite particles used in Example 2 was set so as to have a gap between the regulating blade 58 and the toner carrier 2 or about 250 μm. It is put in the developing device, the gap between the developing roller and the electrostatic image holding member is kept at 300 μm, a toner layer of about 80 μm is formed on the developing roller, and as an AC waveform, a frequency component of 200 Hz and a peak value of ± 450 V DC component − When 250 V was applied and the peak voltage values of -700 V and +200 V were applied and development was performed, the same good results as in Example 1 were obtained.

Comparative Example 4 Using the above materials, a red positively-charged toner having an average particle size of 10 μm and prepared in the same manner as in Example 3 (T _A = + 17.5 μC /
g) 100 parts by weight has a specific surface area of about 90 m ² synthesized by the wet method.
When only 0.4 part of untreated silicic acid fine powder of / g was mixed, T _B of the mixture was +12.1 μC / g, and T _B was 5.4 μ from T _A.
C / g was low and T _A / T _B was 1.4, which did not satisfy the conditions in the present invention. Using this mixture, a two-component type developer was prepared in the same manner as in Example 3, and the same test as in Example 3 was carried out. As a result, the number of continuous copies increased, and a thin image was formed.

〔The invention's effect〕

As described above, according to the positively chargeable developer of the present invention, the charge of the developer is not only stored at normal temperature and normal humidity but also in various environments such as high temperature and high humidity and low temperature and low humidity, and even after repeated copying for a long time. The image quality is not deteriorated and the image quality is not deteriorated. The image reflection density is always high and a good image without fog is obtained.

[Brief description of drawings]

1 and 2 are sectional views showing different forms of a developing device used for carrying out the developing method according to the developer of the present invention. FIG. 3 is an explanatory diagram of a triboelectric charge amount measuring device according to the present invention. 1 ... Electrostatic image carrier 2 ... Toner carrier 3 ... Hopper 5 ... Toner or one-component developer 6 ... Development bias power supply 11 ... Suction device 12 ... Measuring container 13 ... Conductive screen 14 …… Metal lid 15 …… Vacuum gauge 16 …… Air flow control valve 17 …… Suction port 18 …… Condenser 19 …… Potometer 48 …… Magnetic roller 49 …… Non-magnetic sleeve 50 …… Permanent magnet 52 …… Magnetic brush 53 ... Two-component developer in which toner or magnetic carrier is mixed with it 58 ... Regulating blade

Claims (1)

[Claims] 1. A copolymer containing at least 2 to 15% by weight of an aminoacrylic component as a constituent in all binder resins.
Positively chargeable developer containing 100 parts by weight of positively chargeable toner containing 30% by weight or more, 0.01 to 3 parts by weight of positively chargeable silicic acid fine powder, and 0.1 to 5 parts by weight of negatively chargeable fluorine-containing resin fine particles. And the triboelectrification amount T _A of the positively chargeable toner is T _A ≧ + 20 μC / g, and the triboelectrification of a mixture of the positively chargeable toner, the silicic acid fine powder, and the negatively chargeable fluorine-containing resin fine particles. When the amount is T _B , the amount of positively charged triboelectric charge is suppressed so that 1.2 ≦ T _A / T _B ≦ 3, and T _B is
_A positively chargeable developer characterized by being lower than T _A by 6.8 μC / g or more.