JPH0812439B2 - 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 chargeable developer containing a positively chargeable toner and a positively chargeable silicic acid fine powder.

[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 or in a uniformly thin layer coating state on a carrier in a developing section, and that state is maintained. Electrostatic attraction and physical adhesion are the dominant forces to achieve. That is, it becomes necessary to precisely control the amount of electrostatic charge and the triboelectric charging ability of the toner.

However, 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 a special environment of high temperature / high humidity / low temperature / low humidity. It is accompanied. Particularly in the case of positively chargeable toner, it is a constituent element of the toner,
It is very difficult to evenly and positively charge resins, pigments, fluidizers, abrasives, lubricants, etc., and in particular, they can be fully charged even under high temperature and high humidity conditions such as 35 ° C and 85% RH. It was extremely difficult.

[Problems to be solved by the invention]

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

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

An object of the present invention is to provide a positively chargeable developer which is uniformly positively charged even in an environment where charging is unlikely to occur under high temperature and high humidity, and which exhibits a good image.

[Means and Actions for Solving Problems]

That is, the present invention is a positively chargeable toner containing 100 parts by weight of a poorly water-soluble fatty acid or fatty acid derivative in an amount of 0.01 to 20 wt% with respect to the total binder resin, and containing a substance having a positive chargeability. Positively charged developer having at least 0.01 to 3 parts by weight of fine silicic acid powder, and the triboelectric charge amount T _{A of the} positively charged toner is T _A ≧ + 20 μC / g. When the triboelectrification amount of the mixture with the silicic acid fine powder is T _B , 1.2 ≦ T _A / T _B ≦ 3, more preferably 1.2 ≦ T _A / T _B ≦ 2. Quantity is suppressed and T _B
Is lower than T _A by 6.7 μC / g or more.

The toner referred to here is an integrated particle obtained by kneading, crushing, classifying or melting, spraying (dispersing) granulating, or polymerizing granulating the raw material, and the fluidizing agent and charge controlling agent after that. It is different from the form of the developer having an external additive that is put into practical use by mixing particles with.

As a result of earnest studies, the inventors of the present invention have found that a positively chargeable developer having a positively chargeable toner can be used for a long time after copying, at high temperature and high humidity,
One of the major causes of fluctuations in charging ability in a special environment of low temperature and low humidity is quantitative change of fine powder of silicic acid added to toner as a fluidity improver or charge control agent and qualitative change due to moisture absorption / drying. I was confirmed. Further, the present inventors have examined the constitution relating to the charging between the toner and the silicic acid fine powder, and found that the toner has a large positive charging ability to some extent, and the positively charged silicic acid fine powder rather suppresses the charge. It is extremely favorable for the material composition of the positively chargeable developer that it is confirmed that the chargeability is stable as a whole and that the above-mentioned conditions are satisfied, as shown in Examples described later. I found that.

By taking such a constitution and further containing a sparingly water-soluble fatty acid or a fatty acid derivative in the toner, it is possible to further stabilize the charge even under high temperature and high humidity where charge control is said to be difficult. I found that.

The positively chargeable toner used in the present invention can be produced by including a conventionally known substance having a positive chargeability, and the fatty acid or fatty acid derivative shown in the present invention has the ability to make the toner positively charged. Holds.
However, when the toner is positively charged with only a fatty acid or a fatty acid derivative, its charge amount is low, and its ability is not sufficient in an environment in which electric charges easily leak such as high temperature and high humidity. Therefore, as the toner of the present invention, a toner containing 50% by weight (%) or more of a styrene-based copolymer containing 1 to 15% by weight of an aminoacrylic monomer is most preferable because it has a large triboelectric charge amount. As the aminoacryl monomer, all known ones can be used, but generally, the one represented by the following structural formula is effective.

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 , R ₄ is an alkyl group having 1 to ₄ carbon atoms As a constituent component other than aminoacryl of the above-mentioned copolymer, conventionally known Although all of the known monomers can be used, it is generally desirable to contain 70% by weight or more of styrene-acrylic comonomer. Styrene-based monomers include, for example, styrene, vinyltoluene, α-methylstyrene, etc., and acrylic-based monomers include acrylic acid; esters of methyl acrylate, ethyl, propylene, butyl, 2-ethylhexyl, and methacryl. Acids: Methyl, ethyl, propyl, butyl, 2-hexyl esters of methacrylic acid, etc. can be mentioned, respectively. 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.

The sparingly water-soluble fatty acid or its derivative of the present invention is added for the purpose of further improving the stabilization of the charge amount and the image under the special environment of the toner having the above-mentioned constitution, especially under high temperature and high humidity. 12 to 30 fatty acids, metal soaps derived from fatty acids, esters, sulfates, sulfonates and the like are used, and preferably fatty acids having 12 to 30 carbon atoms which are solid at room temperature or metal salts or ester compounds thereof, for example Saturated fatty acids such as lauric acid, palmitic acid, stearic acid and naphthenic acid or unsaturated fatty acids such as oleic acid and linoleic acid are used alone or in a mixture with a salt or in an ester compound with an alcohol. More preferably palmitic acid,
Stearic acid, oleic acid, naphthenic acid and / or a polyvalent metal salt thereof or an ester with glycerin may be used alone or in combination of two or more.

The poorly water-soluble in the present invention means 1000 ml of deionized water.
To have a solubility of 1 g or less.

The sparingly water-soluble fatty acid or its derivative of the present invention may be kneaded with the binder resin to be contained in the toner, or may be supported in the binder resin in advance. Its content is 0.01 to 20 wt% (preferably 0.1
.About.5 parts) is preferable.

When the content of fatty acid or fatty acid derivative is within the above range, when the content is less than 0.01 wt%, the compatible dispersion of toner constituents is insufficient, resulting in aggregation of toner, deterioration of fluidity, and friction of toner under high temperature and high humidity. A phenomenon such as a decrease in chargeability and charge controllability occurs. On the other hand, if it is more than 20% by weight, the compatible components of the toner are sufficiently dispersed, but the toner agglomeration phenomenon and the concentration decrease phenomenon in durability occur under high humidity.

As the positively charged silicic acid fine powder used in the present invention,
Although the one whose variation of triboelectric charge amount due to 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 is used. 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 silicic acid fine powder, the silicic acid fine powder produced by the dry method and the wet method can be used.

The dry method referred to here is a method for producing a fine powder of citric acid 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, aluminum chloride,
Alternatively, it is possible to obtain a composite fine powder of silicic acid and another metal oxide by using another metal halogen compound such as titanium chloride together with a silicon halogen compound, and these are also included.

Examples of commercially available fine silica powder (silica) 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 MS-75 HS-5 EH-5 Wacker HDK N 20 (WACKER-CHEMIE CMBH) V15 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 reaction formula is abbreviated below), 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.

Any of silicates such as anhydrous silicon dioxide (silica), aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be applied to the silicic acid fine powder here.

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 Soda Tokuyama Vita Seal Taki Manure Shiruton, Shirunetsuku Mizusawa Chemical Starsil Kamijima Kagaku Himesir Ehime Pharmaceutical Syroid Fuji Debison Kagaku Hi-Sil (High Seal) Pittsburgh Plate Class.Co. (Pittsburgh Silver Plate) Doulosir) Fiillstoff-Gesellschaft Ultorasil (Ultraseal) Marquart (Manufacturer) Manosil (Manosir) Hardman and Holden (Hoesch K-G) Chemische Fabrik Hoesch KG Shiru Stone Stoner Rubber Co. (Stoner Rubber) Nalco (Nalco) Nalco Chem. Co. (Nalco Chemical) Quso (fucking) Philadelphia Quartz Co. Imsil Illinois Minerals Co. Calcium Silikat Chemische Fabrik Hoesch KG Calsil Fiillstoff-Gesellschaft Marquart (FoltaFill) Imperial Chemical Industries. Ltd. (Imperial Chemical Industries) Microcal (Microcal) Joseph Crosfiels & Sons.Ltd. (Joseph Crossfield and Sands) Manosil (Manosir) Hardman and Holden (Hardman and Holden) Vulkasil (Burkasil) Farbenfabriken Bryer. A.-G. (Hualben Hua Breeken Bayer) Tufknit (Tahnit) Durham Chemikcals.Ltd. (Doulham Chemicals) Sirmos Shiraishi Kogyo Starletx Kamijima Of Manabu Purikoshiru multi wood fertilizer the fine silica powder, the specific surface area by nitrogen adsorption measured by BET method is 30 m ² / g or more (especially 50 to 400 m ² / g) in the range of giving 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 alkoxyl 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.) Amine on a commercially available side chain As the silicone oil having a, for example, an amine-modified silicone oil represented by the following structural formula is preferable. that is (Here, R ₁ , R ₄ , and R ₅ represent an alkyl group or 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.) Specifically, the following silicone oils are preferable, and these may be used in one kind or in a mixture of two or more kinds.

The amine equivalent is equivalent to one amine (g /
eqiv) is the value obtained by dividing the molecular weight 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 function 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 vigorously agitated while being heated if necessary, and the silicone oil having an amine in the side chain or a solution thereof is sprayed or vaporized and sprayed on this, or the 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.

In particular, a method of spraying or vaporizing a silicone oil having an amine in the side chain or a solution thereof and spraying it onto the silicic acid fine powder is a preferable method from the viewpoint of processing uniformity. Further, it is preferable from the viewpoint of charge stability of the treated silicic acid fine powder that the silicone oil having an amine in the side chain is cured and crosslinked on the silicic acid fine powder by heating after the treatment once. The best heating temperature is 270-350 ° C. If the temperature is lower than that, the triboelectricity of the treated silicic acid powder is lowered, and it may not be possible to satisfy the conditions of the present invention when externally added to the toner. Decomposes easily, making positive charging impossible.

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 the positively chargeable toner may be set to 6.7 μC / g or more and the ratio T _A / T _{B of the} triboelectric charge amount may be set so as to satisfy the above condition. When it is added in an amount of 0.01 to 3 parts by weight, it exhibits an effect, and particularly preferably, when added in an amount of 0.03 to 1.5 parts by weight, it exhibits positive stability and excellent stability.

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, Prommethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and terminals with 2 to 12 siloxane units per molecule There is dimethylpolysiloxane having a Si-bonded hydroxyl group for each unit located at. These are used alone or as a mixture of two or more.

In the present invention, it is possible to add other resins, polymers, etc. to the toner in addition to the above copolymers. Examples thereof include polystyrene, polystyrene-butadiene copolymers, styrene-based copolymers such as styrene-acrylic copolymers, polyethylene, polyethylene-vinyl acetate copolymers,
Examples thereof include ethylene-based copolymers such as polyethylene vinyl alcohol copolymer, phenol-based resins, epoxy-based resins, allyl phthalate resins, polyamide resins, polyester resins, maleic acid-based resins and the like. 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, dye and pigment can be used.

It is also possible to add other lubricants, abrasives, etc. 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.

An image forming method using the positively chargeable developer of the present invention includes an electrostatic charge image formed on an electrostatic charge image support by an electrostatic charge image forming method such as an electrophotographic method, an electrostatic recording method and an electrostatic printing method. To
It is developed with the above-mentioned developer. For example, in electrophotography, as shown in FIG. 4, electrostatic charge is applied to the surface of a drum 61 made of a photoconductive photoconductor rotated in the direction of an arrow by a charging mechanism 62 such as a corona charger, A light image of the original is projected onto the surface of the document by the exposure mechanism 63 to form an electrostatic charge image. This electrostatic charge image is developed by the developing device 64 filled with the above-mentioned developer.
To develop a developer image.

As the developing method here, a method according to the characteristics of the developer is used, a magnetic brush developing method, a cascade developing method, a method using a conductive magnetostatic developer described in U.S. Pat.No. 3,909,258, Method using a high-resistance magnetic developer described in JP-A-53-31136, JP-A-54-42141
JP-A-55-18655, the method described in JP-A-55-18655, the fur brush developing method, the powder cloud method, the imprinting method and the like.

The developer image thus formed is transferred onto a transfer agent such as transfer paper. In the example of FIG. 4, the developer image is electrostatically transferred onto the transfer paper that is synchronously conveyed along the transfer paper path p indicated by the chain line by the action of the transfer discharger 65. As the transfer means, various means such as pressure transfer and thermal transfer can be used. Then, the transfer agent which has received the transfer of the developer image is then conveyed to a fixing device and subjected to a fixing process by a contact heating fixing system using a heating roller, for example, whereby a visible image is formed.

On the other hand, the electrostatic charge image support that has undergone the transfer process is subjected to a cleaning process after being neutralized, if necessary, and then subjected to the next image forming process. In the example of FIG. 4, the static charge on the drum 1 is made to disappear by the action of the discharging static electricity discharger 66, and in the figure, the cleaning mechanism 67 by the cleaning blade removes the toner particles remaining on the drum 1. It is removed and cleaning is performed. Here, the cleaning system is optional, but it is preferable to use the blade cleaning system or the fur brush cleaning system capable of surely achieving the required cleaning, and it is possible to sufficiently cope with high-speed image formation. . The blade cleaning method is a method in which a scraping blade is provided so that the leading edge of the blade contacts the surface of the electrostatic charge image support to be moved for cleaning, and the structure is simple and energy is not required. A blade cleaning method is preferable as a combination with the developer of the present invention.

In particular, organic photoconductors (OPC) as photoconductive photoreceptors
When the residual transfer developer is cleaned by using a blade cleaning method, the developer of the present invention exhibits extremely good cleaning properties. This is because the fine silicic acid powder has the same polarity as the toner and adjusts the chargeability of the toner to an appropriate value, so that it does not adhere too strongly to the toner surface or is not too far away from the toner, and therefore a suitable amount on the toner is obtained. It is dispersed by adhesion. Therefore, it is considered that it is possible to act as a lubricant or an abrasive, and to adjust the appropriate abrasiveness-sliding property between the OPC photosensitive member and the blade.

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 fine silica powder 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 The above materials were kneaded, pulverized, and classified to obtain a positively charged toner having an average particle size of 10 μm. The triboelectric charge amount T _A of the positively chargeable toner is
It was +51.6 μC / g.

On the other hand, 100 parts by weight of fine silicic acid powder (trade name, Aerosil # 130, specific surface area and 130 m ² / g, manufactured by Aerosil Co., Ltd.) synthesized by a dry method are stirred while silicone oil having an amine in a side chain (25 ° C. Viscosity at 70 cps, amine equivalent 8
00) 15 parts by weight was sprayed and treated for 10 minutes, and stirring was continued for 20 minutes at about 280 ° C. for heat treatment.

100 parts by weight of the red positively chargeable toner and 1.0 part by weight of finely charged positively chargeable silicic acid powder treated with the silicone oil having an amine in the above side chain were externally mixed. The triboelectric charge amount T _B of the obtained mixture was +31.8 μC / g, T _A was 19.8 μC / g lower than T _B , and T _A / T _B was 1.6.

6 parts of the mixture of the positively chargeable toner and fine powder of positively chargeable silicic acid and 100 parts of irregular iron powder having a particle size of 300 to 400 mesh are mixed to obtain a two-component developer, and an OPC photoreceptor is obtained. Canon NP-500 modified by throwing in to form a negative latent image
0 When the image was put into a copier and an image was taken out, a clear image without fog was obtained and the image reflection density was 1.38.
Further, when images were similarly printed in a high temperature and high humidity environment (35 ° C., 85% RH), the image density was 1.36, and an image free from problems such as fog was obtained. This image continued after copying 10,000 sheets. Further, the cleaning property of the photoconductor by the blade cleaning method was also good.

Comparative Example 1 The positively chargeable toner of Example 1 was prepared by adding 1.0% of fine silicic acid powder which was not treated with a silicone oil having an amine in a side chain.
% When externally mixed, T _B was 13.7 μC / g, and T _A / T _B
Was 3.8, which did not satisfy the conditions of the present invention.

Using this two-component developer, the same test as in Example 1 was carried out. As the number of copies increased, the image was more fogged than in Example 1. Also, under a high temperature and high humidity environment, it became a thin image.

Comparative Example 2 Styrene butyl acrylate copolymer 95 parts (copolymerization ratio 80:20) Monoazo red pigment 5 parts Quaternary ammonium salt (positive charge control agent) 2 parts Using the above materials, Similarly, a positively chargeable toner was obtained. Triboelectric charge amount T _{A of the} obtained positively charged toner
Was +8 μC / g. Next, 100 parts by weight of the positively chargeable toner and 0.8 part by weight of the positively chargeable silicic acid fine powder prepared in Example 1 were externally added and mixed.

The triboelectric charge T _B of the obtained mixture was +10 μC / g, and
_B was 2 μC / g higher than T _A , and T _B / T _A was about 0.80.

Using the mixture, an image development test was carried out in the same manner as in Example 1. As a result, an image reflection density of 1.35 was initially obtained, but when 10,000 sheets were used for durability, an image reflection density of 0.
It dropped to 87. Also, in the image output test under high temperature and high humidity environment, the image reflection density of the initial image was as low as 0.91.

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 developer, 43 is a developing device, 48 is a magnetic roller, 49 is its non-magnetic sleeve, 50 is a magnet, 52 is a magnetic brush, and 53 is one. Component developer or mixture of developer and magnetic particles. By holding the magnetic carrier on the non-magnetic sleeve 49 with a magnetic force to form a brush and rotating the sleeve 49, the toner or the developer is formed.
The uniform one-component developer 5 is formed by scooping 53 with the above-mentioned carrier brush and applying it on the toner carrier 2 by contact. At that time, since the magnetic particles are held on the magnetic roller 48 by the magnetic force, they do 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 one-component developer layer on the toner carrier 2 is about 5 to 100 μm. Toner carrier 2 and electrostatic image carrier 1
The developing bias voltage may be applied to the toner carrier 2 such that the gap between the toner carrier 2 and the toner is larger than the thickness of the one-component developer layer.

Average particle size by melt-kneading, cooling, crushing and classifying the above materials
12 μ of positively chargeable toner was obtained. T _A of positively charged toner is +
It was 30.8 (μC / g).

100 parts of this positively chargeable toner and 0.6 part of the positively chargeable silicic acid fine powder prepared in Example 1 were mixed. T _B of the mixture + 24.1MyuC a / g, T _B than T _A 6.7μC / g low, T _A / T _B
Was 1.3.

A two-component developer obtained by mixing 10 parts of the mixture of the positively-charged toner and finely-charged silicic acid powder and 100 parts of the iron powder carrier of Example 1 is used to form a gap between the toner carrier 2 and the magnetic roller 48. It is put in the developing device shown in FIG. 1 which is set so that the maximum thickness of the magnetic brush 52 is about 2 mm and about 3 mm, and the gap between the developing roller and the electrostatic image carrier is kept at 300 μ, and the toner layer of about 80 μ is formed. It is formed on the developing roller and the frequency is 200H as an AC waveform.
When a DC component of -250 V was added to the z voltage peak value of ± 450 V and voltage peak values of -700 V and +200 V were applied and development was performed using a Canon Copier PC-20, the same good results as in Example 1 were obtained. 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 bias power source for development, 5 is a one-component developer, 50
Is a fixed magnet, 52 is a magnetic brush made of a mixture of magnetic particles and toner, and 58 is 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 silica externally added toner in the hopper 3 is taken in to uniformly coat the toner carrier 2 in a thin layer. Next, the toner carrier 2 and the electrostatic image carrier 1 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 carrier 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, a mixture of positively charged toner and positively charged silicic acid fine powder prepared in the same manner as in Example 1 except that stearic acid glyceride was used instead of aluminum palmitate (T _A was 43.6 μC / g. , T _B is 22.1 μC / g and T _B is T _A
21.5 μC / g lower than that, and T _A / T _B is 2.0) 20 g was mixed with 20 g of iron powder particles in advance to prepare a two-component developer, and the obtained two-component developer was mixed with the regulating blade 58 and the toner. It is put into the developing device shown in FIG. 2 which is set so that the gap between the carrier 2 and the carrier is about 250μ, the gap between the developing roller and the electrostatic image carrier is kept at 300μ, and a toner layer of about 80μ is placed 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, and a peak voltage of −700 V and +200 V was applied to develop, and the same good result was obtained.

〔The invention's effect〕

By using a positively chargeable toner based on the material structure of the present invention and a positively chargeable developer having a positively chargeable silicic acid fine powder,
Even after repeated copying for a long period of time, the charge of the developer did not decrease and the image did not deteriorate, and it was possible to always provide a good image. Further, since the toner has a stable charging ability even under a special environment of high temperature and high humidity and low temperature and low humidity, a stable image can be displayed against various environmental changes.

[Brief description of drawings]

1 and 2 are cross-sectional views showing different forms of a developing device used for carrying out the developing method according to the present invention. FIG. 3 is an explanatory diagram of a triboelectric charge amount measuring device according to the present invention.
FIG. 4 is an explanatory view schematically showing the process of electrophotography. 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 containing toner or magnetic particles mixed with it 58 …… Regulation blade 61 …… Drum 62 …… Charging mechanism 63 …… Exposure mechanism 64 …… Developer 65 …… Transfer discharger 66 …… Discharger for static elimination 67 …… Cleaning mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Uchida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP 59-201063 (JP, A) JP 58-185405 (JP, A) JP 59-34539 (JP, A) JP 59-83171 (JP, A) JP-A-61-184554 (JP, A) JP-A-59-137955 (JP, A) JP-B-53-22447 (JP, B2)

Claims (1)

[Claims] 1. A positively chargeable toner containing 100 parts by weight of a poorly water-soluble fatty acid or a fatty acid derivative in an amount of 0.01 to 20 wt% with respect to the entire binder resin and containing a substance having a positive chargeability.
A positively chargeable developer having at least 0.01 to 3 parts by weight of positively chargeable silicic acid fine powder, wherein the triboelectric charge amount T _{A of the} positively chargeable toner is T _A ≧ + 20 μC / g, and the positively chargeable toner is The triboelectrification amount of positive charge is suppressed so that 1.2 ≦ T _A / T _B ≦ 3, where T _B is the triboelectrification amount of the mixture of the silica fine powder and T _B and T _B
Is 6.7 μC / g or more lower than T _A , a positively charged developer.