JPH04355459A - Full color toner for electrostatic image development and image forming method using this toner - Google Patents

Abstract

PURPOSE:To provide a satisfactory image over a long period by using a specified polypropylene as a low molecular weight releasing agent. CONSTITUTION:Any one coloring agent of cyan, magenta, and yellow, a binder resin, and a low molecular weight releasing agent are mainly contained. As the low molecular weight releasing agent, polypropylene is used. The stereoscopic structure of the polypropylene contains at least isotactic polypropylene and atactic polypropylene, wherein the content of the isotactic polypropylene is 80% or more, the crystallinity of the polypropylene is 30% or more, the melting point of the polypropylene is within the range of 70-150 deg.C, and the difference between the melting start temperature and the melting end temperature is less than 50 deg.C. Thus, the filming to a developing sleeve and a photosensitive body and the fixation of a carrier to a spent blade are prevented, and a satisfactory image can be provided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a full-color toner for developing electrostatic images and a full-color image forming method using the toner.

0002

[Prior Art] Generally, in electrophotography or electrostatic recording, a developing method is used to develop an electrostatic image formed on a latent image carrier made of a photoconductor or dielectric. After developing on a toner supply roller such as a sleeve using toner that has been made into a thin layer with a blade, etc., and that has been appropriately charged and pulverized, the toner image is transferred to a transfer material such as paper as necessary. Then, a copy is obtained by fixing by heating pressure, solvent vapor, etc.

The developing methods applied to these electrophotographic methods are broadly divided into dry developing methods and wet developing methods. The former is further divided into methods using a two-component developer and methods using a one-component developer.

Two-component developing methods include a magnetic brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using fur, etc., depending on the type of carrier for conveying the toner.

[0005] Also, those belonging to the one-component development method include:
(i) Powder cloud method using toner particles in a spray state, (ii) Contact development method (contact development or toner development) in which toner particles are developed by bringing them into direct contact with an electrostatically charged surface, (iii) Toner particles are A jumping development method in which toner particles are charged and flown toward the electrostatic image surface by the electric field of the electrostatic image without directly contacting the electrostatic image surface; (iv) the magnetic conductive toner is placed on the electrostatic image surface; There is the MagneDry method, which develops the film by contacting it.

[0006] Toners applied to these developing methods include:
In order to improve the offset property at the fixing part, low molecular weight polyethylene or polypropylene is mixed as a mold release agent. In this case, the low molecular weight polyethylene or polypropylene has poor compatibility with the polystyrene used as the binder resin, so phase separation occurs during melt-kneading. The interface due to phase separation is easily destroyed by the application of mechanical force, and a phenomenon is observed in which the toner is pulverized.

For example, at the contact surface between the photoreceptor and paper,
A phenomenon of toner pulverization occurs at the contact surface between the developing sleeve (toner conveying member) and the blade, at the contact surface between the toner carrier and further at the contact surface between the developing sleeve and the photoreceptor.

[0008] For example, in the case of a contact development method, the pulverized toner adheres to the developing sleeve, causes a fusion phenomenon over time, and forms a film on the developing sleeve. When a filming phenomenon starts to appear on the developing sleeve,
Non-uniformity occurs in the thickness of the thinned toner layer, which causes non-uniform distribution of the amount of charge during development of the electrostatic latent image, which causes non-uniformity in the amount of toner adhering per unit area on the developing sleeve. As a result, shading also occurs on the copy, which is a serious problem in terms of images. Further, in the case of the magnetic brush method, for example, the finely powdered toner is spent on the carrier due to frictional heat generated between the carrier and the toner, which causes the toner to fuse and develop over time. When the toner components melt and adhere to the surface of the carrier, the ability of the carrier to charge the toner begins to decline over time, causing serious problems such as scumming and density unevenness in images.

[0009] The pulverization of the toner caused by the fragility of the toner particles means that they are easily crushed by mechanical force, which is preferable from the viewpoint of toner productivity alone.

[0010] Therefore, in order to avoid such a filming phenomenon, it is possible to use a polymer with a high molecular weight. This increases the amount of heat and requires a larger amount of heat during fixing, which is undesirable from the viewpoint of energy saving or miniaturization of hardware equipment. Furthermore, in order to eliminate this phenomenon, it has been proposed to add a small amount of plasticizer to the toner, but there are problems such as impairing the free flow properties of the toner and contaminating the carrier etc. Not successful. Furthermore, if the toner is too hard, it becomes impossible to mechanically crush it or to be sufficiently dispersed by kneading.

[0011] Until now, for the above reasons, relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymer, etc., which can have appropriate hardness, have been used as binder resins for color toners. . However, for devices such as laser printers that use electrophotography and require maintenance-free operation, relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymers do not have sufficient hardness; It has become clear that materials with high quality are required. In addition, this type of binder resin has insufficient properties for heat fixing using hot rolls, which are commonly used at present, and the melting of the binder resin for color toner due to heat and its adhesion to paper, etc. Although the condition is good, there is an offset phenomenon to the heat roller.

[0012]Furthermore, a fluidization promoter is often used to suppress filming on the developing sleeve or photoreceptor and spending on the carrier. For example, JP-A-47-3
Publications such as JP-A No. 6405 and JP-A No. 47-36830 mention the use of metal soaps, while JP-A No. 52-153441 and JP-A-53-147541 mention the use of fluorine compounds. No. 54-8534 proposes the use of a nonionic surfactant, and JP-A-56-62256 proposes the use of silica whose surface has been made hydrophobic.

Furthermore, Japanese Patent Laid-Open No. 56-66856 discloses that particles harder than the toner are embedded in the toner surface.
In Japanese Patent Application Laid-open No. 58-134651, it is disclosed in Japanese Patent Application Laid-Open No. 59-1319 that an ion exchange resin is contained in a binder resin.
No. 43 discloses that oxidized polyethylene is used as a mold release agent to exhibit a mold release effect while maintaining compatibility with the binder resin, and JP-A-56-197048 discloses that silicone oil is contained in the binder resin. JP-A-59-220748 discloses that wax fine particles are externally added to the toner, and JP-A-60-138,565 discloses that carbon black is externally added to reduce the resistance of the toner. 186851 No. 186851, Japanese Patent Publication No. 1868-
186852, JP 60-186853, JP 60-186854, JP 60-186855,
JP-A-60-186857, JP-A-60-18685
No. 8, JP-A-60-186860, JP-A-60-18
No. 6861, JP-A-60-186862, JP-A-60
In publications such as JP-A-186863, JP-A-60-186864, JP-A-60-186865, and JP-A-60-186866, it is disclosed that polymer fine particles are externally added.
Furthermore, in JP-A No. 61-99164, an abrasive (SiC
, SiN) has been proposed.

On the other hand, as a fixing method, a press-heating method using a heating roller is generally used, in which the toner image surface of the sheet to be fixed is placed on the surface of the heating roller whose surface is made of a material that has releasability to the toner. Fixing is performed by passing through the toner image while making pressure contact with the toner image, and is generally called the heated roller fixing method. , the thermal efficiency when fusing the toner image onto the fixing sheet is extremely good, and the toner image can be fixed quickly. However, in this method, the surface of the fixing roller and a portion of the toner image may adhere to the surface of the fixing roller, causing a so-called offset phenomenon and causing stains on the sheet to be fixed (receiving paper).

In order to prevent the occurrence of the offset phenomenon, there is a method of supplying a liquid with release properties such as silicone oil to the surface of the fixing roller to cover the roller surface with a thin film of the liquid, and a method of adding a resin with release properties to the toner. Method of containing
No. 304), there is a method in which these methods are performed simultaneously. However, when a general low molecular weight polypropylene is used to impart releasability to the toner, a phenomenon in which the toner is offset to the fixing roller often occurs when the fixing roller becomes hot.

[0016] However, the use of the above-mentioned additives alone can cause problems such as filming on the developing sleeve and photoreceptor.
The reality is that the effect of suppressing spent on carriers and furthermore preventing the offset phenomenon from occurring is still insufficient.

[0017]

[Problems to be Solved by the Invention] The present invention suppresses filming on the developing sleeve and photoreceptor due to frictional heat between the developing sleeve and the photoreceptor, as well as spending on the carrier and sticking to the blade. A full-color toner for developing electrostatic images that has a permanent effect, gives good copied images, and has good low-temperature fixing properties, anti-offset properties, and good release properties; and image formation using this full-color toner. The present invention provides a method.

[0018]

[Means for Solving the Problems] The first aspect of the present invention is cyan,
A full-color electrostatic charge developing product containing either magenta or yellow colorant, a binder resin, and a low molecular weight mold release agent as main components, wherein (a) the three-dimensional structure of polypropylene is at least isotactic. Contains atactic polypropylene and atactic polypropylene, of which the content of isotactic polypropylene is 80% or more, (b) polypropylene crystallinity is 30%
% or more, and (c) the melting point of the polypropylene is in the range of 70 to 150°C, and the difference between the melting start temperature and the melting end temperature is 50°C or less. It is characterized by the fact that

The second aspect of the present invention is a full color image forming method in which a thin layer of color toner is supplied to a latent image carrier and an electrostatic charge image is visualized by electrophotography using a one-component development method. It is characterized in that the first color toner of the present invention is used as the toner.

Incidentally, the present inventors conducted studies from various angles in order to achieve the above-mentioned object, and as a result, it was found that it can be achieved by using low-molecular-weight polypropylene having specific properties as a mold release agent. I made sure of that. That is, the actactic polypropylene component present in polypropylene causes problems such as offset phenomenon, so when the content of isotactic component in polypropylene was increased to 80% or more, surprisingly, the It has been found that the offset phenomenon is greatly improved. Furthermore, by increasing the crystallinity of polypropylene to 30% or more, offset phenomena can be further improved, and
It has been found that by setting the melting point of polypropylene to be in the range of 70 to 150°C and the difference between the melting start temperature and the melting end temperature being 50°C or less, offset phenomena etc. can be further improved. The present invention has been made based on this knowledge.

The invention will now be explained in more detail with reference to the accompanying drawings (FIG. 1). Note that the image forming apparatus shown in FIG. 1 shows only its main parts, and it may be modified to some extent.

By the way, toner is generally composed of a plurality of polymers, and the polymers are mixed at a micron level by melt-kneading. This state can be clearly seen by dyeing a cross section of the toner and observing it with a transmission electron microscope (TEM). The equipment used was Luzex III manufactured by Nireco.) The oil resist toner is usually mixed with a low molecular weight release agent such as low molecular weight polypropylene, low molecular weight polyethylene, or wax in order to impart release properties and to prevent offset during fixing. These mold release agents such as low molecular weight polypropylene receive thermal energy from the fixing roller during fixing, thereby acting to prevent toner offset to the fixing roller by seeping out of the toner.

On the other hand, toner adheres to the developing sleeve, photoreceptor, or carrier over time, resulting in a phenomenon called filming. As a result of surface analysis, it was found that the main component of this filming substance was low molecular weight polypropylene, which is present in the toner and has a releasing effect.

[0024] Therefore, when we analyzed low molecular weight polypropylene in which this filming easily occurs, we found that such low molecular weight polypropylene has three types of isomers that differ in steric structure: isotactic type,
It has been found that syndiotactic and atactic polypropylenes are included.

[0025] Furthermore, as a result of further consideration regarding this point,
Atactic polypropylene is industrially used as an adhesive and has extremely high tackiness.If polypropylene containing a large amount of this polypropylene is used as a release agent, toner particles during fixing may The mold releasability of the film deteriorates, causing a filming phenomenon on the developing sleeve, photoreceptor, and even carrier. At this time, if the content of isotactic polypropylene is 80% or less, an offset phenomenon occurs to the fixing roller during fixing, and filming on the photoreceptor and spent phenomenon on the carrier often occur. Further, if the degree of crystallinity of polypropylene is 30% or less, although the filming phenomenon on the photoreceptor is not so observed, the offset phenomenon on the fixing roller occurs. Further, if the melting point of polypropylene is 70° C. or lower, there is a problem in storage stability, and there is a problem in that the product (color toner) aggregates during transportation or storage in a warehouse or the like. Melting point is 150℃
If the amount exceeds the amount, the fixing energy becomes extremely large, leading to problems such as an increase in the cost and power consumption of the fixing device. Further, if the temperature difference between the melting start temperature and the melting end temperature of polypropylene is 50° C. or more, an offset phenomenon occurs in this case as well, which is a problem.

As the binder resin used in the color toner obtained by the present invention, all known binder resins can be used. For example, monopolymers of styrene and its substituted products such as polystyrene and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, and styrene-methyl acrylate copolymers. styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, Styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Styrenic copolymers such as vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropylene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride,
Polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin,
Terpene resins, phenolic resins, aliphatic or aliphatic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

As the coloring agent, all known ones for full color toners can be used. Examples of cyan colorants include phthalocyanine blue, methylene blue,
Victoria blue, methyl violet, aniline blue, ultramarine blue, etc. can be used. As the magenta coloring agent, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake, etc. can be used. Examples of yellow colorants include chrome yellow,
Benzidine yellow, Hansa yellow, naphthol yellow, molbdenum orange, quinoline yellow, tartrazine, etc. can be used. Other black coloring agents that may be used as necessary include carbon black,
Aniline black, furnace black, lamp black, etc. can be used.

These color toners may contain, for example, dyes and pigments, charge control agents, etc., in order to provide more efficient charging. Examples of the charge control agent include metal complexes of monoazo dyes, nitrofumic acid and its salts, salicylic acid, naphthoic acid, metal complexes of dicarboxylic acids such as Co, Cr, and Fe, organic dyes, and quaternary ammonium salts.

The toner may be produced by any conventionally known method, for example, by adding a binder resin, a colorant, and a charge control agent to 120%
It is obtained by melting and kneading with hot rolls at ℃, solidifying by cooling, pulverizing with a jet mill, and classifying.

[0030] The full color toner of the present invention may contain, if necessary, additives for toners that are generally widely used, such as a fluidizing agent such as colloidal silica, titanium oxide,
It may contain metal oxides such as aluminum oxide, abrasives such as silicon carbide, lubricants such as fatty acid metal salts, and the like. However, since the toner of the present invention is for full color use, the amount of these toners to be blended is naturally limited. The additive may be mixed with the toner by any conventionally known method, and may be mixed using an apparatus such as a Henschel mixer or a speed kneader.

[0031] As the carrier, conventionally known carriers may be used.
Non-coated carriers such as iron powder and ferrite, carriers coated with styrene-acrylic resin, silicone resin, fluorine-modified acrylic resin, etc., granulated carriers, etc. can be used.

Now, in an image forming apparatus that repeats the process of transferring a toner image formed on the surface of an image carrier onto a transfer material mainly made of paper, it is necessary to remove the toner remaining on the image carrier after each transfer process. Therefore, it is desirable to have a cleaning device that is excellent in removing residual toner, has a simple structure, and is advantageous in terms of cost. The cleaning method and apparatus includes mechanically removing toner particles by physically contacting the surface of the imaging member to be cleaned and electrically biasing a portion or other member of the cleaning device to provide a conductive brush. It is based on creating an electrostatic field between the image forming member surface and the insulating imaging member surface to attract the toner on the imaging member surface to the brush and electrostatically remove the toner. Therefore, if the toner on the surface of the photoreceptor, ie, the image forming member, is positively charged, the electrostatic field will be negative.

An electrostatic field between the brush and the surface of the imaging member is created by applying a DC voltage to the brush. Representative examples of this method are USP3572923 and USP372.
It is described in 2018. A more sophisticated version of these electrostatic brush cleaning devices is USP449486.
3. In addition to creating a positive electric field between the imaging member and a cleaning brush to attract and remove charged toner particles from the imaging member, a pair of detoning rolls are installed, one roll being Dust such as paper fibers and clay is removed from the biased cleaning brush. The two detoning rolls are electrically biased so that one roll attracts toner from the brush and the other roll attracts and removes dust.
Even if the collected toner is reused, the quality of the copy will not deteriorate, and the dust can be discarded.

In all brush cleaning systems, a trade-off must be considered between cleaning ability to remove toner from sensitive imaging members and wear and film formation on the imaging member. The electrostatic brush system described in the above US patent allows the brush to rotate relatively slowly. Therefore, there is an advantage that the copy processing speed can be increased while maintaining the speed of the cleaning brush at the same relative speed. Wear may become even more of a problem with the advent of photoconductive materials that do not have as much abrasion resistance as conventional photoconductive materials. For example, photoreceptors consisting of a conductive substrate, a charge generating layer and a charge transport layer in which photoconductive particles are dispersed in an insulating organic resin are particularly susceptible to abrasion from purely mechanical brush cleaning.

Initially, electrostatic brush cleaning devices used brushes made of metal fibers such as stainless steel because they were readily available. This type of cleaning device is effective for certain applications, but in addition to being quite susceptible to wear, the metal fiber brushes tend to become tangled and develop compression set, resulting in premature loss of cleaning performance. , there are some drawbacks. Furthermore, since metal fibers are highly conductive, if even one filament comes into contact with the installation surface, the entire brush will short-circuit, resulting in poor cleaning overall. In addition to it,
Of course, the loose fibers can short out other electrical components such as the coronatron and switches. Finally, stainless steel fibers are sold by weight, making them very expensive compared to other fibers with the lowest specific gravity. This makes it a cheaper alternative to stainless steel fibers.
There is a need to provide more stable fibers with longer lifetimes. Furthermore, for small particle size toners, it is necessary to provide fibers with a charging ability greater than that of conventional filament polymer-based brushes.

As a result of intensive research by the present inventors, it was found that the surface resistance of the brush governs the force that attracts toner particles onto the brush, and that frictional charging force is important at a close distance on the brush. It became clear that Therefore, when the full color toner of the present invention is used in an image forming apparatus provided with a cleaning brush so as to be brought into contact with an image carrier to remove residual deposits, the cleaning brush material is at least a filamentous polymer base material. , the filament polymer base material is positively chargeable when measured by a blow-off method with respect to a negatively chargeable toner, and the surface resistance of the fiber is 1 x 10 3 to 1 x 10 12 Ω. /cm is particularly effective.

[0037] As the filament polymer base material for the cleaning brush, nylon, acrylic, polyester,
General synthetic and natural bonding fibers can be used if they exhibit positive charge when measured by the blow-off method against negatively chargeable toners such as rayon.

The filament polymer base material of the cleaning brush is a polymer base material that is negatively charged when measured by the blow-off method against negatively charged toner, and most of the toner on the photoreceptor can be removed. It's impossible. Furthermore, the surface resistance of the fiber is 1×10
If it is less than 3 Ω/cm, charge will easily be injected into the toner, and it will adhere to the photoreceptor with strong electrostatic force, making it impossible to perform sufficient cleaning. On the other hand, if the surface resistance is 1×10 12 Ω/cm or more, even if a high voltage is applied, hardly any electricity can flow through the filament polymer base material, and sufficient cleaning performance cannot be obtained.

The toner of the present invention is particularly useful for image formation using a one-component development method in electrophotography, and therefore the image forming method of the present invention will be described next.

The image forming method of the present invention is an image forming method using a one-component development method in electrophotography in which a thin layer of toner is supplied to a latent image carrier (photoreceptor) to develop a latent image. It is characterized by using full color toner having specific physical properties. Note that the thinning of the toner is
Usually, it includes a developing sleeve (toner conveying member), a toner layer thickness regulating member, and a toner supplying member, and the toner supplying member and the developing sleeve (toner conveying member), and the toner layer thickness regulating member and the developing sleeve (toner conveying member), respectively. This is done using an abutting device.

FIG. 1 is a schematic cross-sectional view of an example of a developing device using a non-magnetic one-component toner useful for carrying out the method of the present invention. In FIG. 1, the toner 6 of the present invention contained in a toner tank 7 is forcibly brought to a toner supply member (sponge roller) 4 by a stirring blade (toner supply auxiliary member) 5, and the toner 6 is 4. Then, the toner 6 taken into the toner supply member 4
When the toner supply member 4 rotates in the direction of the arrow, it is carried to the developing sleeve (toner conveying member) 2, rubbed, and electrostatically or physically adsorbed, and the developing sleeve (toner conveying member) 2 moves in the direction of the arrow. A uniform thin layer of toner is formed by the toner layer thickness regulating member (elastic blade) 3 made of steel and frictionally charged. after that,
The latent image (electrostatic charge image) is carried to the surface of the electrostatic latent image carrier 1 that is in contact with or in close proximity to the developing sleeve (toner conveying member) 2, and is developed. Note that the developing device suitable for the toner of the present invention is not limited to the one described above.

In such an image forming method using a one-component development method in electrophotography, if finely powdered toner adheres to the developing sleeve and forms a film, it will greatly affect the ability to form a uniform thin layer of toner. The full-color toner of the present invention suppresses pulverization on the photoconductor, etc., and as a result, prevents filming on the photoconductor, etc., so that the toner can be uniformly formed into a single layer on the developing sleeve. form,
The method of the invention provides high quality images over a long period of time.

[0043]

[Examples] Examples of the present invention will be specifically described below, but the present invention is not limited thereto. Note that parts represent parts by weight.

Example 1 Binder resin Polyester resin

90 parts Mold release agent Polypropylene*

10 parts coloring agent chrome yellow
5 parts Charge control agent Salicylic acid zinc salt
Part 2*
The polypropylene used here had an isotactic component of 82%, a melting point of 130°C, and a difference between the melting start temperature and the melting end temperature of 45°C. The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product is classified to have an average particle size of approximately 7.5μ.
It was set as m. The degree of polypropylene crystallinity in the obtained yellow toner was measured and found to be 65%.

Example 2 Styrene-acrylic copolymer

92 parts polypropylene*

Part 8 Phthalocyanine blue
Part 2 Salicylic acid zinc salt

2 parts *The polypropylene used here has an isotactic component of 89%, a melting point of 128°C, and a difference between the melting start temperature and the melting end temperature of 30°C. The mixture having the above composition was melt-kneaded, cooled, and classified to obtain a toner having an average particle size of about 8.3 μm. The degree of polypropylene crystallinity in the obtained cyan toner was measured and found to be 70%.

Example 3 Styrene-acrylic copolymer

92 parts polypropylene*

Part 8 Phthalocyanine blue
Part 2 Quaternary ammonium salt

2 parts *The polypropylene used here has an isotactic component of 94%, a melting point of 125°C, and a difference between the melting start temperature and the melting end temperature of 20°C. The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified to obtain a toner having an average particle size of about 7.5 μm. The degree of polypropylene crystallinity in the obtained cyan toner was measured and was 79%.
Met.

Example 4 Polyester resin

70 parts styrene-acrylic copolymer

20 parts polypropylene*

Part 10 Chrome Yellow

5 parts Salicylic acid zinc salt

2 parts *The polypropylene used here has an isotactic component of 68%, a melting point of 130°C, and a difference between the melting start temperature and the melting end temperature of 45°C. Melt and knead the mixture with the above composition,
The mixture was cooled, pulverized, and classified to obtain a toner having an average particle size of about 7.6 μm. The degree of polypropylene crystallinity in the obtained yellow toner was measured and found to be 28%.

Example 5 Styrene-acrylic copolymer

72 parts polyester resin

20 parts polypropylene*

Part 8
phthalocyanine blue

Part 2 Quaternary ammonium salt

2 parts *The polypropylene used here has an isotactic component of 64%, a melting point of 125°C, and a difference between the melting start temperature and the melting end temperature of 55%.
℃. Melt and knead the mixture with the above composition, cool it,
The powder was crushed and classified to obtain a toner having an average particle size of about 7.5 μm. The degree of polypropylene crystallinity in the obtained cyan toner was measured and found to be 79%.

Comparative Example 1 Polyester resin

90 parts polypropylene*

Part 10 Chrome Yellow

5 parts Salicylic acid zinc salt

2 parts *The polypropylene used here has an isotactic component of 64%, a melting point of 145°C, and a difference between the melting start temperature and melting end temperature of 60°C.
belongs to. The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified to obtain a toner having an average particle size of about 7.8 μm. The degree of polypropylene crystallinity in the obtained yellow toner was measured and found to be 29%.

Comparative Example 2 Styrene-acrylic copolymer

92 parts polypropylene*

Part 8 Phthalocyanine blue
Part 2 Salicylic acid zinc salt

2 parts *The polypropylene used here has an isotactic component of 61%, a melting point of 149°C, and a difference between the melting start temperature and the melting end temperature of 63°C. The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified to obtain a toner having an average particle size of about 7.4 μm. The degree of polypropylene crystallinity in the obtained cyan toner was measured and found to be 22.
%Met.

Comparative Example 3 Styrene-acrylic copolymer

92 parts polypropylene*

Part 8 Phthalocyanine blue
Part 2 Quaternary ammonium salt

2 parts *The polypropylene used here had an isotactic component of 5%, a melting point of 128°C, and a difference between the melting start temperature and the melting end temperature of 55°C. The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified to obtain a toner having an average particle size of about 7.5 μm. The degree of polypropylene crystallinity in the obtained cyan toner was measured and found to be 9%.

5 parts of these toners and 95 parts of non-coated amorphous iron powder carrier were continuously stirred in a ball mill pot to form a developer, which was then set in a modified IMAGIO-320 digital copying machine manufactured by Ricoh Co., Ltd., and used as a photoreceptor. Surface filming and fixing offset were evaluated. At the same time, cleaning failure evaluation was also performed. The results are shown in Table 1.

[0053]

[Table 1] (Note) In the cleaning defect evaluation, Examples 1 to 5
As for the cleaning brush, it is made of nylon and exhibits positive chargeability towards toner, and has a surface resistance of 1 x 106 Ω/cm.
In Comparative Example 1, a cleaning brush made of nylon that exhibits positive chargeability to toner and has a surface resistance of 1 x 106 Ω/cm was used.
In this case, the cleaning brush is made of Teflon and exhibits negative overcharge against toner, and has a surface resistance of 1 x 1015Ω/
cm was used.

On the other hand, using only these toners without using carrier, images were produced using the developing device shown in FIG. 1, and evaluation of filming on the surface of the developing roller and evaluation of fixing offset were performed. The results are shown in Table 2.

[Table 2]

[0055]

Effects of the Invention The full-color toner for developing electrostatic images of the present invention uses a specific polypropylene as a release agent, so when an image is formed using the toner, the toner particles on the photoreceptor or developing sleeve are The pulverization of the toner is suppressed, and as a result, no filming occurs on the photoconductive photoreceptor or the developing sleeve in which the toner adheres and melts. Further, the state in which the adhered toner becomes thin and forms a film does not occur. Furthermore, the frictional electrification between the toner and the developing sleeve etc. is also stably maintained. In addition, the full color toner of the present invention is also useful in one-component development systems.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a developing device using the non-magnetic one-component toner of the present invention useful for carrying out the method of the present invention.

[Explanation of symbols]

1 Electrostatic latent image carrier 2 Toner transport member (developing sleeve) 3 Toner layer thickness regulating member 4 Toner supply member 5 Stirring blade 6 Toner 7 Toner tank

Claims (3)

[Claims] Claim 1: The main components are a cyan, magenta, or yellow colorant, a binder resin, and a low molecular weight mold release agent, and the low molecular weight mold release agent is one of the following (a), (b), and (c). A full-color toner for electrostatic image development characterized by being a polypropylene that satisfies the conditions. % or more. (b) The crystallinity of polypropylene is 30% or more. (c) The melting point of polypropylene is in the range of 70 to 150°C, and the difference between the melting start temperature and the melting end temperature is 50°C.
Must be below ℃. 2. The toner is a filament polymer base material that is positively chargeable when measured by a blow-off method with respect to a negatively chargeable toner, and the surface resistance of the filament is 1×10 3 to 1×10 12 Ω/cm. 2. The full-color toner for developing an electrostatic image according to claim 1, which is used in an image forming apparatus in which a certain cleaning brush is provided in contact with an image carrier. 3. The color toner according to claim 1 is used in a one-component development method of electrophotography in which a thin layer of toner is supplied to a latent image carrier to visualize an electrostatic charge image. A full-color image forming method.