JP4030066B2 - Electrophotographic developer and image forming method - Google Patents

Description

  The present invention relates to an image forming technique in the fields of electrophotography and electrostatic recording. In particular, the present invention relates to a high-speed image forming method using an OPC belt photoreceptor as a latent image carrier and a brush cleaning system as a cleaning means.

  The electrophotographic method generally uses a photoconductive substance, forms an electric latent image on a photoreceptor by various means, and then develops the latent image with toner, and if necessary, on paper or the like. After transferring the powder image, it is fixed by heating or solvent vapor to obtain a copy. Conventionally, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 61-147261) and the like, methods for developing an electrostatic charge image using toner are roughly classified, and toner and carrier are mixed. There are a method using a so-called two-component developer and a method using a one-component developer that is used alone without being mixed with a carrier.

  Of these, the method using a two-component developer charges the toner and the carrier with agitation and friction to charge each of them to different polarities, and the electrostatic charge image having the opposite polarity is visualized (developed) by the charged toner. Depending on the type of toner and carrier, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method, and the like. As a toner applied to these various development methods, fine powder in which a colorant such as carbon black is dispersed in a binder resin made of a natural resin or a synthetic resin is used. For example, particles obtained by finely pulverizing a colorant dispersed in a binder resin such as polystyrene to about 1 to 30 μm are used as toner. Further, those obtained by further containing a magnetic material such as magnetite in these components are used as a magnetic toner.

  In the field of copying machines and printers, not only higher speed and higher image quality, but also miniaturization and higher durability are strongly desired due to market demands. Against this background, development of toners, photoreceptors and charge imparting members has been carried out.

  In the electrostatic charge development method, the cleaning means for removing the untransferred toner after transfer from the latent image carrier is generally performed by bringing a blade or a fur brush directly into contact with the latent image carrier. Since the charge transport layer CTL on the surface of the image carrier is in direct contact with the cleaning member and the developing member, it is subject to wear. In particular, a high-speed machine is required to have photoconductor abrasion resistance that can withstand a very large amount of copying and printing. For this reason, for high-speed machines, a flexible belt-shaped OPC photoconductor that can increase the effective use area of the photoconductor surface and relatively soft cleaning of the photoconductor. The combination of brush cleaning that can be done is the mainstream. However, even such a combination is not sufficient for mass copying exceeding 1 million sheets, and higher durability is desired.

  In recent years, there has been a strong demand for higher definition and higher resolution of copied images. However, the conventional developer has a problem in that the particle size distribution of the toner particles changes in the developer due to the selective development of the toner particles in a long time and large number of copies and prints, and as a result, the resolution of the image is lowered. . On the other hand, in order to obtain such a high-definition and high-resolution image, in the developing system, Patent Document 2 (Japanese Patent Laid-Open No. 1-112253), Patent Document 3 (Japanese Patent Laid-Open No. 2-284158), and Patent Document 4 (Special Japanese Patent Application Laid-Open No. 2-128158). JP-A-7-295283) has proposed a developer having a small average particle diameter and a toner particle content of 5 μm or less and its distribution.

  Here, toner particles of 5 μm or less are essential components for forming a high-definition and high-resolution image, and the latent image is formed when toner having this particle size is smoothly supplied during development of the latent image on the photoreceptor. It is said that an image having excellent reproducibility can be obtained without protruding from the latent image. In addition, the electrolytic strength of the edge portion around the latent image is higher than that of the central portion, so that the amount of toner particles adhering to the inside of the latent image is smaller than that of the edge portion, and the tendency of the image to become thin becomes remarkable with toner particles of 5 μm or less. On the other hand, this problem can be solved by defining the number% of toner particles having an intermediate particle diameter of 5 μm or more.

  However, although a toner having a small particle diameter is advantageous for forming a high-definition and high-resolution image, as a representative example, as shown in FIGS. 1 and 2, 17% by number of toner particles of 5 μm or less are contained. In this case, only 3% by weight of toner particles having a size of 5 μm or less are present in the toner weight distribution, and in this amount, a toner having a small particle size of 5 μm or less is present in the peripheral portion on the latent image in the middle of 5 μm or more. It is unlikely that the toner having the particle size is selectively placed on the center of the latent image. On the other hand, as shown in FIGS. 3 and 4, as a representative example, when toner particles of 5 μm or less are contained in a large amount of 60% by number, the toner particles are likely to be overcharged, which is called charge-up, particularly in a low temperature environment. The charged toner and fine powder adhere firmly to the developer carrier surface and the photoreceptor surface, resulting in a decrease in image density and occurrence of fogging, poor photoreceptor cleaning and filming on the photoreceptor, Cause undesirable problems.

  In Patent Document 5 (Japanese Patent Laid-Open No. 4-1773), in order to solve this problem, the flowability is improved by containing 0.1 to 5.0% by weight of toner particles of 12.7 to 16.0 μm. However, it is sure to be inferior to the toner particles having a particle size of 5 μm or less of 1 to 15% by number.

  On the other hand, it is conceivable to increase the amount of the additive as a method for improving the fluidity. However, the fluidity is considered to be approximately the same when the presence state of the additive on the toner particle surface is the same. When the following is 60% by number, it is necessary to add 1.5 to 2 times the amount of the additive as compared with the toner of 17% by number of 5 μm or less. When a large amount of additive is added in this way, it is clear that photoreceptor contamination, filming, and deterioration of fixability due to the additive cannot be avoided.

  Patent Document 6 (Japanese Patent Laid-Open No. 4-124682) and Patent Document 7 (Japanese Patent Laid-Open No. 10-91000) show the effects of one-component toner as those in which the number of toner particles of 5 μm or less is defined to be small. However, the particle size distribution in the range where most of the toner particles that determine the image quality exist is not described, and it is insufficient to obtain a high-resolution image.

JP 61-147261 A Japanese Patent Laid-Open No. 1-112253 JP-A-2-284158 JP 7-295283 A Japanese Patent Laid-Open No. 4-1773 JP-A-4-124682 Japanese Patent Laid-Open No. 10-91000

  An object of the present invention is to provide a two-component developer that has good fluidity even with a small amount of additives, substantially less photoconductor contamination and filming, and good fixability in view of the above-mentioned problems of the prior art. is there. It is another object of the present invention to provide an image forming method in which the developer is hardly deteriorated even in high-speed mass copying and long-term use, the photoreceptor is less worn, and cleaning failure and filming can be prevented. .

The object of the present invention is to provide (1) an image forming method having a cleaning means for removing residual toner on a latent image carrier after transfer, wherein the two-component developer comprises a magnetic carrier and a toner. Is a toner obtained by mixing 0.3 to 0.5 parts by weight of hydrophobic silica with 100 parts by weight of the base colored particles, containing 1 to 15% by weight of toner particles of 5 μm or less, and having a weight average The relationship between the number average particle diameters D25 and D75 containing toner particles having a diameter twice or more of the particle diameter of 0.3 to 5% by weight or less and a cumulative number distribution of 25% and 75% is 0.70 ≦ D25 / D75. ≦ 0.85, and the weight-average particle size is 6.0 to 11.5 μm ”, (2)“ Cleaning to remove residual toner on latent image carrier after transfer ” In the image forming method having the means, the two components The developer has a magnetic carrier and a toner, and the toner is a toner obtained by mixing 0.3 to 0.5 parts by weight of hydrophobic silica with 100 parts by weight of the base colored particles, and having a particle size of 5 μm or less. Number average particle diameter containing 1 to 12% by number of toner particles, 0.3 to 3% by weight or less of toner particles having a diameter twice the weight average particle diameter, and a cumulative number distribution of 25% and 75% The image forming method , wherein the relationship between D25 and D75 is 0.70 ≦ D25 / D75 ≦ 0.85 and the weight average particle diameter is 6.0 to 9.5 μm ”, (3)“ Latent image ” This is achieved by the image forming method described in the above item (1) or (2), wherein the carrier is an OPC belt photosensitive member, and the cleaning means is a brush cleaning method using a magnetic brush .

  According to the present invention, it is possible to obtain a high image density / high resolution / high definition copy image having good fluidity even with a small amount of additive, substantially less photoconductor contamination and filming, and good fixability. It becomes.

  A toner having the above particle size distribution and containing a predetermined amount of inorganic fine powder that has been hydrophobized has good fluidity even when a small amount of inorganic fine powder is added. Even when copying / printing is continued, high-resolution and high-definition images can be maintained, and even when recycled paper is used, extremely stable images can be formed without problems such as poor cleaning and filming. .

The reason why such an effect is obtained in the toner according to the present invention is not necessarily clear, but is estimated as follows.
That is, one characteristic of the toner of the present invention is that 1 to 15% by number of toner particles having a particle size of 5 μm or less. When the average particle size of the toner is reduced, it is advantageous for forming a high-definition / high-resolution image. However, toner particles having a particle size of 5 μm or less are difficult to control the charge amount or impair the fluidity of the toner. It can be a component that causes contamination, a component that causes poor cleaning and filming problems, and a component that causes toner scattering to stain the inside of the image forming apparatus. In addition, when adding an inorganic oxide to improve the fluidity, the smaller the particle size, the greater the toner surface area. It has become clear that this also causes problems such as photoconductor contamination, filming, and poor fixability. That is, increasing the number of toner particles of 5 μm or less has a good effect on high resolution, but when considering long-term use as a developer, the above problems cannot be solved and may be satisfactory. Absent. Rather, by making the toner particles of 5 μm or less 1 to 15% by number, the fluidity as a toner can be secured with a small fluidity improver, the photoreceptor contamination and filming are substantially reduced, and the fixability is low. A good toner can be obtained. However, in consideration of productivity, it is difficult to make 0% toner particles having a weight average particle diameter of 6.0 to 11.5 μm in a range of 5 μm or less, substantially 1% by number or more, more preferably 3% by number or more is preferable.

  In the toner according to the present invention, the relationship between the number average particle diameters D25 and D75 at which the cumulative number distribution under the sieve is 25% and 75% is 0.60 ≦ D25 / D75 ≦ 0.85. It is a feature. D25 / D75 indicates that the closer the value is to 1, the sharper the particle size distribution of the toner particles having a cumulative number distribution of 25% and 75%. The fact that the particle size distribution of the toner that substantially forms most of the image is sharp means that the characteristics of each toner particle are also equal. As a result, the behavior of each toner in the developing unit is the same, so that selective toner consumption and toner with different charge amounts are reduced, and a high-definition and high-resolution image can be stably formed. .

Further, it is preferable that the amount of toner particles having a diameter equal to or larger than twice the weight average particle diameter is 5% by weight or less and as small as possible.
The above toner can be expected to be effective regardless of whether it is a two-component toner, a one-component toner or a non-magnetic toner.
Furthermore, when the toner of the present invention is used as a two-component toner, the charge amount of the toner can be made more uniform by combining with a magnetic carrier having an average particle diameter of 35 to 100 μm.
The developer of the present invention solves the conventional problems and can withstand severe demands for high image quality and low-temperature fixing in recent high-speed image forming apparatuses and high durability of the photoreceptor.

The configuration of the present invention will be described in more detail.
The toner particles having a size of 5 μm or less may be 1 to 15% by number of the total number of particles, preferably 1 to 12% by number, and more preferably 3 to 12% by number. If the number of toner particles of 5 μm or less is 15% by number or more, the average particle size becomes relatively small, which is advantageous for high resolution, but problems such as toner fluidity deterioration, poor cleaning, and filming. Will occur. However, it is difficult to make it 0%, substantially 1% by number or more, and 3% by number or more is preferable in consideration of productivity.

  Further, the relationship between the number average particle diameters D25 and D75 at which the cumulative number distribution under the sieve is 25% and 75% is preferably 0.60 ≦ D25 / D75 ≦ 0.85, and preferably 0.70 ≦ D25 / D75 ≦ 0.85 is preferable. When D25 / D75 ≦ 0.60, the particle size distribution becomes broad, so that the behavior of each toner particle is not uniform, and selective consumption of toner and toner with different charge amounts cause deterioration of the image. Further, when D25 / D75 ≧ 0.85, a sharp particle size distribution is obtained, which is advantageous for high-resolution image formation. However, since the productivity is extremely reduced in the conventional manufacturing method by dry pulverization classification, it is not substantial. .

  Further, the toner particles having a diameter twice or more of the weight average particle diameter is desirably 5% by weight or less, more preferably 3% by weight or less. If it exceeds 5% by weight, the fine line reproducibility tends to be poor.

  The weight average particle diameter of the toner is 6.0 to 11.5 μm, more preferably 6.0 to 9.5 μm. If the weight average particle size is less than 6.0 μm, problems such as contamination in the machine due to toner scattering during long-term use, image density reduction in a low-humidity environment, and poor photoreceptor cleaning tend to occur. When the weight average particle diameter exceeds 11.5 μm, the resolution of minute spots of 100 μm or less is not sufficient, and the image quality tends to be inferior due to many scattering to non-image areas.

  Furthermore, the average particle diameter of the magnetic carrier is 35 to 100 μm, more preferably 45 to 75 μm. When the average particle diameter of the magnetic carrier is within this range, the toner charge amount can be made more uniform when combined with the toner of the present invention when the toner concentration in the developing device is in the range of 2 to 10% by weight. it can. If it is 35 μm or less, the carrier particles are likely to adhere to the photosensitive member, and the stirring efficiency with the toner becomes poor, and it becomes difficult to obtain a uniform charge amount of the toner. When the thickness exceeds 100 μm, the toner of the present invention is not sufficiently charged, and it is difficult to obtain a uniform charge amount of the toner.

The average particle diameter of the carrier, it is possible to use a method by conventional sieving.

  The toner particle size distribution can be measured by various methods. In the present invention, the toner particle size distribution was measured using a Coulter counter. That is, a Coulter counter TA-ll type (manufactured by Coulter) was used as a measuring device, and the number distribution and weight distribution were connected to an output interface (manufactured by Nikka) and a PC 9801 personal computer (manufactured by NEC). A 1% NaCl aqueous solution is prepared using sodium chloride. As a measurement method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 10 to 15 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. Disperse for ~ 3 minutes. Into another beaker, 100 to 200 ml of an electrolytic aqueous solution was added, and the sample dispersion was added to a predetermined concentration, and 2 to 2 based on the number using a 100 μm aperture as an aperture by the Coulter counter TA-ll type. The particle size distribution of 40 μm particles is measured, the weight distribution and number distribution of 2 to 40 μm particles are calculated, and the weight average particle diameter (D4: the median value of each channel is the representative value of the channel) is determined from the weight distribution. It was.

In addition, the two-component developer of the present invention can be used by adding inorganic fine powder to the toner as a fluidity improver and is particularly preferable. A toner having a particle size distribution as a feature of the present invention has a specific surface area smaller than that of a conventional toner. In this case, when the toner is mixed with a magnetic carrier and used as a two-component developer, the number of contact between the toner particles and the magnetic carrier is reduced as compared with the conventional toner, the carrier surface is contaminated, and the toner particles are worn and disintegrated. Is less likely to occur.
Furthermore, since the specific surface area is reduced, the amount of inorganic fine powder added can be reduced, so that problems such as contamination and filming of the photoreceptor due to the inorganic fine powder and poor fixing are less likely to occur. This can extend the life of the developer and the photoreceptor. Furthermore, toner particles in the range of D25 to D75, which play an important role in the present invention, are further effective due to the presence of a small amount of inorganic fine powder, and can stably provide a high-quality image for a long period of time.

  As the inorganic fine powder of the present invention, Si, Ti, Al, Mg, Ca, Sr, Ba, In, Ga, Ni, Mn, W, Fe, Co, Zn, Cr, Mo, Cu, Ag, V, Zr, etc. And oxides and composite oxides. Of these, fine particles of silicon dioxide (silica), titanium dioxide (titania), and alumina are preferably used. Furthermore, it is effective to perform a surface modification treatment with a hydrophobizing agent or the like. Typical examples of the hydrophobizing agent include the following.

Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinylmethoxysilane, vinyl-tris (β-methoxyethoxy) ) Silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyl Trichlorosilane, decyl-trichlorosilane, nonyl-trichlorosilane, (4-t-propylphenyl) -trichlorosilane, (4-t-butylphenyl) -trichlorosilane, diventyl-dichlorosilane, dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl -Dichlorosilane, didecyl-dichlorosilane, didodecyl-dichlorosilane, dihexadecyl-dichlorosilane, (4-t-butylphenyl) -octyl-dichlorosilane, dioctyl-dichlorosilane, didecenyl-dichlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di- 3,3-dimethylbenthyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane Dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, (4-t-propylphenyl) -diethyl-chlorosilane, octyltrimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane , Hexatolyl disilazane and the like.
In addition, titanate coupling agents and aluminum coupling agents can also be used.

  The inorganic fine powder used in the present invention is preferably used in an amount of 0.1 to 2% by weight based on the toner. If it is less than 0.1% by weight, the effect of improving toner aggregation is poor, and if it exceeds 2% by weight, problems such as toner scattering between fine wires, contamination in the machine, scratches and abrasion of the photoreceptor tend to occur. is there. The key point in the present invention is that a predetermined fluidity can be ensured even if the amount of the inorganic fine powder added is small, and that high resolution image quality can be maintained even when copying and printing a large number of sheets for a long period of time. This is clearly more effective than the case where the toner amount is increased and a large amount of inorganic fine powder is added.

  In addition, the developer of the present invention may further contain other additives within a range that does not substantially adversely affect, for example, a lubricant powder such as Teflon powder, zinc stearate powder, and polyvinylidene fluoride powder; or cerium oxide powder, carbonization Polishing agents such as silicon powder and strontium titanate powder; or conductivity imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder; and small amounts of reverse polarity white fine particles and black fine particles as developability improvers It can also be used.

A conventionally well-known thing can be widely used as binder resin for toners of this invention. For example, it consists of vinyl resin, polyester resin or polyol resin.
Examples of vinyl resins include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers thereof: styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer. Polymer, styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methacrylic copolymer Acid methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Coalescence, styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene copolymers such as copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate and the like.

The polyester resin is composed of a dihydric alcohol as shown in the following group A and a dibasic acid salt as shown in the group B, and further a trihydric or higher alcohol as shown in the group C or Carboxylic acid may be added as a third component.
Group A: ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4 butanediol, neopentyl glycol, 1,4 butenediol, 1,4-bis (hydroxymethyl) cyclohexane Bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,2′-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -2,2′-bis (4 -Hydroxyphenyl) propane and the like.

  Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, linolenic acid, or These acid anhydrides or esters of lower alcohols.

  Group C: Trivalent or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol, and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid.

As the polyol resin, an alkylene oxide adduct of an epoxy resin and a dihydric phenol, or a compound having one active hydrogen in the molecule that reacts with the glycidyl ether and the epoxy group, and an active hydrogen that reacts with the epoxy resin in the molecule. There are those obtained by reacting two or more compounds. In addition, the following resins can be mixed and used as necessary.
Epoxy resin, polyamide resin, urethane resin, phenol resin, butyral resin, rosin, modified rosin, terpene resin, etc. The epoxy resin is typically a polycondensate of bisphenol such as bisphenol A or bisphenol F and epichlorohydrin.

The following are used as the pigment used in the present invention.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. .
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.
Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of green pigments include chrome green, chromium oxide, pigment green B, and malachite green lake.
These can use 1 type (s) or 2 or more types.

  Further, a release agent can be internally added to the toner in the present invention to prevent offset at the time of fixing. Examples of the release agent include natural waxes such as candelilla wax, carnauba wax and rice wax, montan wax, paraffin wax, sazol wax, low molecular weight polyethylene, low molecular weight polypropylene, and alkyl phosphate ester. These are selected depending on the binder resin and the fixing roller surface material. The melting point of these release agents is preferably 65 to 90 ° C. When the temperature is lower than this range, blocking during storage of the toner tends to occur, and when the temperature is higher than this range, an offset is likely to occur in a region where the fixing roller temperature is low.

  In the developer of the present invention, it is preferable to use a charge control agent mixed with developer particles (internal addition) or mixed with developer particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. For controlling the toner to be positively charged, nigrosine, a quaternary ammonium salt, an imidazole metal complex and salts can be used alone or in combination of two or more. Further, salicylic acid metal complexes, salts, organic boron salts, calixarene compounds, and the like are used for controlling the toner to be negatively charged.

  When the magnetic toner is used, the toner particles may contain magnetic fine particles. Such magnetic materials include metals, alloys such as ferrite, magnetite and other irons, nickel, cobalt, etc., or compounds containing these elements, and those containing no ferromagnetic elements, but by applying an appropriate heat treatment. An alloy that exhibits ferromagnetism, for example, a seed alloy called Heusler alloy containing manganese and copper such as manganese copper aluminum and manganese-copper-tin, chromium dioxide, and the like. It is preferable that the magnetic material is contained in a uniformly dispersed form in the form of fine powder having an average particle size of 0.1 to 1 μm. The content of the magnetic material is preferably 10 to 70 parts by weight, particularly preferably 20 to 50 parts by weight, with respect to 100 parts by weight of the obtained toner.

  As the carrier used in the developer of the present invention, known carriers can be used. For example, magnetic particles such as iron powder, ferrite powder, nickel powder, and magnetite powder, or the surface of these magnetic particles are coated with a fluororesin or vinyl resin. Examples thereof include those treated with a resin, a silicone-based resin, and the like, or magnetic particle-dispersed resin particles in which magnetic particles are dispersed in the resin. The average particle size of these magnetic carriers is preferably 35 to 75 μm.

As an example of a method for producing the toner according to the present invention, first, the binder resin, the pigment or dye as the colorant, the charge control agent, the lubricant, other additives, etc. are sufficiently obtained by a mixer such as a Henschel mixer. After mixing, batch type twin rolls, Banbury mixer and continuous twin screw extruder, for example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., manufactured by KCK Thermal kneaders such as a twin screw extruder, a PCM type twin screw extruder manufactured by Ikekai Tekko Co., Ltd., a KEX type twin screw extruder manufactured by Kurimoto Ironworks Co., Ltd. The components are thoroughly kneaded, cooled, coarsely pulverized using a hammer mill, etc., further pulverized by a fine pulverizer or mechanical pulverizer using a jet stream, and a classifier or coanda using a swirling airflow. Classification using effects By classifying the predetermined particle size.
Next, the inorganic fine powder and the toner are sufficiently mixed by a mixer such as a Henschel mixer, and then passed through a sieve of 250 mesh or more to remove coarse particles and aggregated particles, thereby obtaining the toner of the present invention. Further, when used as a two-component developer, the two-component developer is finally obtained by mixing with the above-described magnetic carrier at a predetermined mixing ratio.

Next, an embodiment in which the image forming method of the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) will be described.
First, the configuration and operation of the copier according to the present embodiment will be described with reference to FIG. 7 which is a schematic configuration diagram of the copier (201). The copier (201) in this embodiment is mainly composed of a scanner (101) as image reading means and a printer (112) as image output means. The scanner (101) is for optically reading an original image, and includes a contact glass (209) as an original placement table, an exposure lamp (210), a reflection mirror (211), an imaging lens (212), And a CCD image sensor (213). As the exposure lamp (210), a halogen lamp is generally used. Reading of an original image by the scanner (101) is performed as follows.

  The original placed on the contact glass (209) is irradiated with light by an exposure lamp (210), and the reflected light from the original is guided to the imaging lens (212) by a reflecting mirror (211) or the like. The reflected light is imaged on the CCD image sensor (213) by the imaging lens (212). The CCD image sensor (213) converts the reflected light into a digital electric signal corresponding to the document image. The CCD image sensor (213) is a full-color image sensor, which color-separates a given optical signal into, for example, each color of R (red), G (green), and B (blue), and outputs digital signals corresponding to the colors. Output a signal. The CCD image sensor (213) is arranged in a row in a direction perpendicular to the drawing (this direction is also referred to as a main scanning direction). The digital electric signal that is the output of the CCD image sensor (213) is subjected to image processing such as color conversion processing in an image processing unit, which will be described later, to be cyan (hereinafter referred to as C), magenta (hereinafter referred to as Cagenta), M), yellow (Yellow: hereinafter referred to as Y), and black (hereinafter referred to as BK) color image data. Based on these color image data, the printer (112) described below visualizes the toner with C, M, Y, and BK toners, and the obtained toner images are superimposed to form a full-color image.

  A photoconductor (215) as an image carrier is disposed at a substantially central portion of the printer (112). The photoreceptor (215) is an organic photoreceptor (OPC) drum, and its outer diameter is about 120 mm. Around the photosensitive member, a charging device (207) for uniformly charging the surface of the photosensitive member, a BK developing unit (202), a C developing unit (203), an M developing unit (204), and a Y developing unit (205). An intermediate transfer belt (206), a cleaning device (214), and the like are disposed. Further, above the photoconductor (215) and below the scanner (101), a light beam is generated based on the color image data described above to uniformly charge the photoconductor (215). A laser optical system (208) for optically scanning the surface is provided. The laser optical system (208) includes a laser diode that generates a light beam, a polygon mirror that deflects the light beam, and the like.

  An image forming operation in the printer (112) performed with such a configuration will be described as an example based on BK image data. The latent image formed on the surface of the photosensitive member (215) by the light beam based on the BK image data from the laser optical system (208) is developed by the corresponding BK developing unit (202), and the BK toner image It becomes. This toner image is transferred to the intermediate transfer belt (206). Hereinafter, the transfer of the toner image from the photoreceptor (215) to the intermediate transfer belt (206) is referred to as belt transfer. The series of operations of latent image formation, development, and belt transfer as described above is performed for four colors C, M, Y, and BK, and a four-color superimposed toner image is formed on the intermediate transfer belt (206). Is done. The four-color superimposed toner images are collectively transferred by a transfer bias roller (217) onto a recording medium fed from the paper supply unit (216), for example, a recording paper. The recording medium on which the four-color superimposed toner image is formed is conveyed to the fixing device (219) by the conveyance belt (218). The fixing device (219) melts a four-color toner image by heating and pressing and fixes the toner image on a recording medium. The recording medium on which the fixing is completed is discharged onto a paper discharge tray (220). On the other hand, the toner remaining on the surface of the photoconductor (215) is collected by the cleaning device (214), and the surface of the photoconductor (215) is cleaned. The surface of the photoreceptor (215) after cleaning is discharged by a discharging device. Further, after the four-color superimposed image is transferred from the intermediate transfer belt (206) onto the recording medium, the toner remaining on the intermediate transfer belt (206) is collected by the belt cleaning device (222), and the intermediate transfer belt ( 206) The surface is cleaned.

  Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way. In addition, all the parts in the following mixing | blending are a weight part.

Reference example 1
Binder resin Polyol resin 100 parts Colorant Carbon black 10 parts Charge control agent Salicylic acid zinc salt 5 parts Mold release agent Low molecular weight polyethylene 5 parts The above raw materials are sufficiently mixed with a mixer, and then kneaded temperature 120 with a twin screw extruder. Melt kneading was carried out at 0 ° C. The kneaded product is cooled and rolled, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then 5 μm or less is 15.0% by number, D25 / D75 = 0.63 using a swirling air classifier. More than twice the weight average particle size, the particle size distribution was 4.3% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (1). Table 1 shows the particle size distribution of the obtained toner. Table 2 shows the results of measuring the loose apparent density and the aggregation rate in order to evaluate the fluidity of the toner.
The loose apparent density was obtained from the weight of toner dropped from a 250 mesh sieve by a powder tester PT-N type manufactured by Hosokawa Micron Corporation and collected from the weight. The agglomeration rate was obtained by the following formula using a powder tester PT-N type manufactured by Hosokawa Micron Corporation, and using a sieve with openings of 150 μm, 75 μm, and 45 μm, and sieving the sample under conditions of vibration time of 60 sec.

本トナーを平均粒径１００μｍのフェライト粒子にシリコン樹脂を表面にコートしたキャリア９７．５部に対し、２．５部の割合で混合し、二成分現像剤を作成した。

This toner was mixed at a ratio of 2.5 parts to 97.5 parts of a carrier in which silicon resin was coated on the surface of ferrite particles having an average particle diameter of 100 μm to prepare a two-component developer.

The obtained developer was set in an Rigoh IMAGO DA505 having a latent image carrier as an OPC drum photoreceptor and a cleaning method as blade cleaning, and the fixability was evaluated. The fixing property is that the solid image is fixed at the center temperature of the designated fixing temperature of the copying machine and the fixing temperature of −30 ° C., and the solid image is scratched with a drawing tester manufactured by Ueshima Co., Ltd. under a load of 50 g. Were evaluated on a scale of 1-5. The larger the value is, the better the fixing property is, and when it is less than 3, it becomes easy to peel off with poppy rubber or the like, so that it is practically unusable.
Furthermore, 800,000 sheets of running were performed to evaluate the cleaning failure, filming occurrence, and image resolution. As for the image resolution, the thin line resolution of the image evaluation standard S-3 test chart was observed with a magnifying glass, and rank evaluations of 1 to 5 were performed. The larger the value, the higher the resolution of the fine line and the higher the resolution. The evaluation results are shown in Table 2.

Reference example 2
A two-component developer was prepared in the same manner as in Reference Example 1 except that a carrier having an average particle size of 30 μm was used in Reference Example 1, and the same evaluation as in Reference Example 1 was performed. The results are shown in Tables 1 and 2.

Reference example 3
A two-component developer was prepared in the same manner as in Reference Example 1 except that a carrier having an average particle diameter of 50 μm was used in Reference Example 1, and the same evaluation as in Reference Example 1 was performed. The results are shown in Tables 1 and 2.

Reference example 4
The classification conditions were changed in Reference Example 1, and the particles were classified into a particle size distribution in which 5 μm or less was 15.0% by number, D25 / D75 = 0.68, and the weight average particle diameter was not less than 2.2% by weight. Furthermore, 0.5 part of hydrophobic silica was mixed with 100 parts of the base colored particles by a Henschel mixer to obtain a toner (2). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Example 1
The classification conditions were changed in Reference Example 1, and the particles were classified into a particle size distribution in which 5 μm or less was 12.1% by number, D25 / D75 = 0.71, and the doubled weight average particle diameter was 1.5% by weight. Further, 0.5 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (3). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Example 2
The classification conditions were changed in Reference Example 1, and the particles were classified into a particle size distribution in which 5 μm or less was 7.2% by number, D25 / D75 = 0.82, and the weight average particle diameter was not less than 0.3% by weight. Further, 0.5 part of hydrophobic silica was mixed with 100 parts of the base coloring particles by a Henschel mixer to obtain a toner (4). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Reference Example 5
Binder resin Styrene-methyl acrylate copolymer 100 parts Colorant Carbon black 10 parts Charge control agent Nigrosine 3 parts The above raw materials were sufficiently mixed with a mixer and then melt-kneaded at a kneaded material temperature of 110 ° C with a twin-screw extruder. The kneaded product is cooled and rolled, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then 14.8% by number or less of 5 μm or less using a swirling air classifier, D25 / D75 = 0.63. More than twice the weight average particle size, the particle size distribution was 3.7% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base coloring particles by a Henschel mixer to obtain a toner (5). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3. The obtained developer was set in an RPC FT9001II in which the latent image carrier was an OPC belt photoconductor and the cleaning method was magnetic brush cleaning, and the same evaluation as in Reference Example 1 was performed. The results are shown in Tables 1 and 2.

Example 3
The classification conditions were changed in Reference Example 5 to classify into a particle size distribution in which 5 μm or less is 3.2% by number, D25 / D75 = 0.74, and the weight average particle diameter is not less than 1.5% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (6). Then create a two-component developer in the same manner as in Reference Example 5, was evaluated in the same manner as in Reference Example 5. The results are shown in Tables 1 and 2.

Reference Example 6
Binder resin Polyester resin 100 parts Colorant Quinacridone magenta pigment
(CI Pigment Red 122) 8 parts Charge control agent Salicylic acid zinc salt 3 parts The above raw materials were kneaded, pulverized and classified in the same manner as in Reference Example 1, and 5 μm or less was 14.9% by number, D25 / D75 = 0 .63, a particle size distribution in which the double diameter of the weight average particle diameter is 4.2% by weight or more was classified. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a color toner (7). Thereafter, a two-component color developer was prepared in the same manner as in Reference Example 3, set in a Ricoh full color copying machine PRETER550, and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Reference Example 7
Binder resin Polyester resin 100 parts Colorant Copper phthalocyanine blue pigment
(CI Pigment Blue 15: 3) 3.5 parts Charge control agent Salicylic acid zinc salt 5 parts The above raw materials are kneaded, ground and classified in the same manner as in Reference Example 1, and 5 μm or less is 14.8% by number, D25 /D75=0.64, more than twice the weight average particle size was classified into a particle size distribution of 4.1% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a one-component color toner (8). The obtained toner was set in a Ricoh SP10PS ProII, which is a one-component printer, and the same evaluation as in Reference Example 1 was performed. The results are shown in Tables 1 and 2.

Reference Example 8
Binder resin Styrene-methyl acrylate copolymer 100 parts Magnetic material Iron trioxide 80 parts Charge control agent Salicylic acid zinc salt 4 parts The above raw materials are kneaded, ground and classified in the same manner as in Reference Example 1, and 5 μm or less. Was 15.0% by number, D25 / D75 = 0.63, and a particle size distribution in which the weight average particle diameter was not smaller than 4.3% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a one-component magnetic toner (9). The obtained toner was evaluated in the same manner as in Reference Example 10. The results are shown in Tables 1 and 2.

Comparative Example 1
The classification conditions were changed in Reference Example 1, and the particles were classified into particle size distributions of 23.5% by number of 5 μm or less, D25 / D75 = 0.65, and 1.7% by weight or more of twice the weight average particle diameter. Further, 0.5 part of hydrophobic silica was mixed with 100 parts of the base coloring particles by a Henschel mixer to obtain a toner (10). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 2
The classification conditions were changed in Reference Example 1, and the particles were classified into particle size distributions of 23.5% by number of 5 μm or less, D25 / D75 = 0.65, and 1.7% by weight or more of twice the weight average particle diameter. Further, 0.7 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (11). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 3
The classification conditions were changed in Reference Example 1, and the particles were classified into particle size distributions of 70.0% by number of 5 μm or less, D25 / D75 = 0.67, and 0.3% by weight or more of twice the weight average particle diameter. Further, 3.0 parts of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (12). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 4
The classification conditions were changed in Reference Example 1, and the particles were classified into particle size distributions of 70.0% by number of 5 μm or less, D25 / D75 = 0.67, and 0.3% by weight or more of twice the weight average particle diameter. Further, 1.0 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (13). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 5
The classification conditions were changed in Reference Example 1, and the particles were classified into a particle size distribution of 14.6% by number of 5 μm or less, D25 / D75 = 0.72, and 8.1% by weight or more of the double diameter of the weight average particle size. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (14). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 6
The classification conditions were changed in Reference Example 1 and classified into a particle size distribution in which 5 μm or less was 10.34% by number, D25 / D75 = 0.59, and the weight average particle size was not less than 0.7% by weight. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of the base colored particles with a Henschel mixer to obtain a toner (15). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 7
The classification conditions were changed in Reference Example 1, and the particles were classified into a particle size distribution in which 5 μm or less was 0.3% by number, D25 / D75 = 0.87, and the weight average particle size was not less than 0.0% by weight. The yield at this time was 21%, which was significantly lower than other classification conditions, and was not at a level that could be substantially produced. Further, 0.3 part of hydrophobic silica was mixed with 100 parts of base coloring particles by a Henschel mixer to obtain a toner (16). Thereafter, a two-component developer was prepared in the same manner as in Reference Example 3 and evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.

Comparative Example 8
The classification conditions were changed in Reference Example 5 to classify into a particle size distribution in which 5 μm or less is 37.0% by number, D25 / D75 = 0.58, and the weight average particle size is not less than 4.4% by weight. Furthermore, 0.3 part of hydrophobic silica was mixed with 100 parts of the base coloring particles by a Henschel mixer to obtain a toner (17). Then create a two-component developer in the same manner as in Reference Example 5, was evaluated in the same manner as in Reference Example 5. The results are shown in Tables 1 and 2.

Comparative Example 9
A toner (18) was obtained in the same manner as in Comparative Example 8, except that the amount of hydrophobic silica in Comparative Example 8 was 0.6 part. Then create a two-component developer in the same manner as in Reference Example 5, was evaluated in the same manner as in Reference Example 5. The results are shown in Tables 1 and 2.

It is a figure which shows the typical number particle size distribution in case the conventional particle | grains of 5 micrometers or less are 17 number%. It is a figure which shows the typical weight particle size distribution in case the conventional particle | grains of 5 micrometers or less are 17 number%. It is a figure which shows the typical number particle size distribution in case the conventional particle | grains of 5 micrometers or less are 60 number%. It is a figure which shows the typical weight particle size distribution in case the conventional particle | grains of 5 micrometers or less are 60 number%. It is a figure which shows the typical number particle size distribution of the toner of this invention. It is a figure which shows the typical weight particle size distribution of the toner of this invention. It is a cross-sectional view of a full-color copying machine used in Example 6.

Explanation of symbols

101 Scanner 112 Printer 201 Copier 202 Black Development Unit 203 Cyan Development Unit 204 Magenta Development Unit 205 Yellow Development Unit 205 Intermediate Transfer Belt 207 Charging Device 208 Laser Optical System 209 Contact Glass 210 Exposure Lamp (Halogen Lamp)
211 Reflection mirror 212 Imaging lens 213 CCD image sensor 214 Cleaning device 215 Photoconductor 216 Paper feed unit 217 Transfer bias roller 218 Conveying belt 219 Fixing device 220 Paper discharge tray 221 Bias roller 222 Belt cleaning device

Claims (3)

In the image forming method having a cleaning means for removing the toner remaining on the latent image bearing member after the transfer, the two-component developer have a magnetic carrier and a toner, the toner, to the base colored particles 100 parts by weight A toner obtained by mixing 0.3 to 0.5 parts by weight of hydrophobic silica, containing 1 to 15% by number of toner particles having a size of 5 μm or less, and toner particles having a diameter more than twice the weight average particle size 0.3 to 5 wt% and containing less a relation 0.70 ≦ D25 / D75 ≦ 0.85 the number average particle size D25 and D75 cumulative number distribution is 25% and 75%, weight average particle diameter Is 6.0 to 11.5 μm. In the image forming method having a cleaning means for removing the toner remaining on the latent image bearing member after the transfer, the two-component developer have a magnetic carrier and a toner, the toner, to the base colored particles 100 parts by weight A toner obtained by mixing 0.3 to 0.5 parts by weight of hydrophobic silica, containing 1 to 12% by number of toner particles having a size of 5 μm or less, and toner particles having a diameter twice the weight average particle size or more. contains from 0.3 to 3 wt% or less, a relation 0.70 ≦ D25 / D75 ≦ 0.85 the number average particle size D25 and D75 cumulative number distribution is 25% and 75%, weight average particle diameter Is 6.0 to 9.5 μm. 3. The image forming method according to claim 1, wherein the latent image carrier is an OPC belt photoreceptor, and the cleaning means is a brush cleaning system using a magnetic brush .

Images