JP2008122604A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner which achieves a smaller particle diameter, high durability and oilless property without reducing productivity. <P>SOLUTION: The toner is manufactured by melting raw materials including a binder resin, a colorant and a release agent, extruding the resulting melt from a pierced die to form a threadlike kneaded product having a diameter equivalent to that of the toner, and carrying out cutting or grinding, wherein cellulose or a derivative thereof or a predetermined low molecular weight thermoplastic resin is added as a grinding aid to the raw materials. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner that has excellent durability and can be reduced in size and oilless.

  In recent electrophotographic systems, there are high demands for high image quality, high speed, and ecology. The requirements for the toner are to reduce the particle size for high image quality, to improve the durability and low-temperature fixability of the toner for high speed, and to separate the silicone oil etc. on the fixing roll for ecology. One example is the elimination of oil molds.

  Of these requirements, in order to achieve oil-less, it is effective to contain a large amount of wax in the toner. However, by increasing the amount of wax, in the pulverized toner, the wax is segregated at the pulverization interface. As a result, internal contamination with toner, fusion to a doctor blade, and the like occur, and the durability deteriorates. Wax segregation also affects image quality.

  In particular, as the toner has a smaller particle size (5 to 7 μm), the specific surface area increases, so that the tendency of wax segregation increases. In addition, reducing the particle size increases the pulverization energy and increases the cost.

  Conventionally, polyethylene (PE) or polypropylene (PP) having a melting point of about 100 to 130 ° C. has been used as a release agent internally added to the toner. A low melting point release agent having a melting point of 100 ° C. or less is effective and has been studied. However, the low-melting-point wax is likely to have problems in terms of durability compared to PE and PP.

  Compared with pulverized toners, polymerized toners are very advantageous for reducing the particle size and adding high concentrations of wax, but use a polyester resin that is narrow in material selection and suitable for color toners. There are problems such as being unable to do so. Another problem is that a large capital investment is required.

  As described above, at the same time, it is very difficult for conventional pulverized toners to simultaneously achieve the reduction in particle size, high durability, and oil-less required for toners. As a method for efficiently producing toner particles, several methods have been proposed in which raw materials are melted and extruded from a die having a hole to form a fibrous kneaded material, which is then cut to produce fine particles ( For example, see Patent Documents 1 to 3).

  As a result of repeated tests on this method, the inventors have melted the raw material, extruded from a die having a hole, and formed a fibrous kneaded material corresponding to the toner diameter, and cut this to produce fine particles. It has been found that the toner obtained by this method can increase the release agent without impairing the durability as compared with the toner obtained by kneading and pulverizing with a conventional twin screw extruder, for example. As a result, it has become possible to provide a toner that simultaneously achieves particle size reduction, high durability, oillessness, and high image quality, which has been difficult in the past.

However, when a high concentration of a low melting point release agent having a melting point of 100 ° C. or less was added, a phenomenon that the grindability was greatly deteriorated occurred. This is presumably because the fiberized kneaded material was softened by adding a low melting point release agent at a high concentration, and as a result, it became difficult to grind.
JP-A-6-138704 JP-A-7-248648 JP 2004-332130 A

  An object of the present invention is to provide an electrophotographic toner which is made under the circumstances as described above and achieves a small particle size, high durability, oil-less property, and high image quality without impairing productivity. And

  In order to solve the above problems, a first aspect of the present invention is to melt a raw material containing a binder resin, a colorant, and a release agent, and extrude it from a die having a hole to obtain a thread-like kneaded material having a toner equivalent diameter. Provided is a toner produced by cutting or pulverizing a thread-like kneaded product after the formation, wherein cellulose or a derivative thereof is added to the raw material as a pulverization aid.

  In such an electrophotographic toner, examples of the cellulose derivative include at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate. Moreover, it is desirable that the particle diameter of cellulose or a derivative thereof is 50 μm or less.

  The second aspect of the present invention is produced by melting a raw material containing a binder resin and a colorant, extruding from a die having a hole, forming a thread-like kneaded material having a toner equivalent diameter, and then cutting or grinding. The number average molecular weight Mn measured by GPC is 600 to 2000, the softening point is 100 ° C. to 160 ° C., and the glass transition point Tg is 55 ° C. to 55 ° C. An electrophotographic toner characterized by adding a low molecular weight thermoplastic resin at 100 ° C. is provided.

  In such an electrophotographic toner, an aromatic petroleum resin can be used as the low molecular weight thermoplastic resin.

  In the first and second electrophotographic toners of the present invention described above, those having a melting point of 70 to 100 ° C. can be used as the release agent. Specific examples of the release agent include carnauba wax or Fischer-Tropsch wax.

  Moreover, as a binder resin, what has a softening point of 110-150 degreeC can be used. As a specific example of the binder resin, polyester can be used.

  The first and second electrophotographic toners of the present invention preferably have an average volume particle size of 5 to 7 μm.

  The first and second electrophotographic toners of the present invention have an elastic developing roller for carrying and transporting the toner, and the thickness of the toner to form the toner in a thin layer on the elastic developing roller. And a toner layer regulating member for regulating, and can be suitably used for a developing device in which the conveying speed of the elastic developing roller is 100 mm / second or more.

  According to the present invention, there is provided an electrophotographic toner that has improved pulverization properties and achieves small particle size, high durability, oil-less properties, and high image quality without impairing productivity.

  The best mode for carrying out the invention will be described below.

  The toner for electrophotography according to the first embodiment of the present invention is obtained by melting a raw material containing an internal additive such as a binder resin and a colorant, and extruding from a die having a hole, and having a toner equivalent diameter. After the formation of the toner, the toner is produced by cutting or pulverizing the thread-like kneaded product, characterized in that cellulose or a derivative thereof is added as a pulverization aid.

  As the cellulose derivative, at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate can be used.

  Cellulose or a derivative thereof plays a role as a grinding aid in a cutting or grinding step in the toner production process described later. By adding cellulose or a derivative thereof, it is possible to simultaneously achieve a reduction in particle size, high durability, and oil-less properties without impairing grindability.

  The content of cellulose or a derivative thereof in the toner is in the range of 1 to 50% by mass and preferably 5 to 30% by mass in the raw material blend. If the content of cellulose or a derivative thereof in the toner is too large, fogging due to poor charging occurs frequently. If it is too small, the effect of addition is difficult to obtain.

  An electrophotographic toner according to a second embodiment of the present invention is a yarn-like kneaded material having a toner equivalent diameter obtained by melting a raw material containing an internal additive such as a binder resin and a colorant and extruding from a die having a hole. After the formation of the toner, the toner was prepared by cutting or pulverizing the thread-like kneaded product, and as a pulverization aid, the number average molecular weight Mn measured by GPC was 600 to 2000, and the softening point was 100 ° C. to A low molecular weight thermoplastic resin having a glass transition point Tg of 55 ° C. to 100 ° C. at 160 ° C. is added.

  This low molecular weight thermoplastic resin is generally used as a so-called tackifier that imparts tackiness by blending with an elastomer such as rubber. Tackifiers are natural resins such as rosin, modified rosin, rosin ester, terpene resin, modified terpene resin, terpene phenol resin, hydrogenated terpene resin, synthetic resin, aliphatic petroleum resin, aromatic petroleum resin, copolymer Examples include petroleum resins, alicyclic resins, chroman indene resins, phenol resins, xylene resins, and the like.

  The low molecular weight thermoplastic resin used in the second embodiment of the present invention has a molecular weight Mn of 600 to 2000, a softening point of 100 ° C to 160 ° C, and a Tg of 55 ° C to 55 ° C. It must be in the range of 100 ° C. If the molecular weight, softening point, and Tg are too low, the durability deteriorates. If it is too high, the effect of improving the grindability is diminished. As for the softening point, it is necessary to select a temperature at which the raw material is sufficiently melted in the process of melting the raw material.

  By adding such a low molecular weight thermoplastic resin to the raw material, an excellent toner satisfying durability, low-temperature fixability, oilless property, and high image quality can be obtained.

  As a compounding quantity of a low molecular weight thermoplastic resin, it is the range of 1-50 mass% during raw material compounding, and 5-30 mass% is more preferable. If the amount is too small, the effect of addition cannot be obtained, and if it is too large, fusion during pulverization tends to occur.

  The binder resin used for the toner according to the first and second embodiments of the present invention can be selected from a wide range including known ones. Specific examples include styrene resins such as polystyrene, styrene-acrylic acid ester copolymers, styrene-methacrylic acid copolymers, and styrene-butadiene copolymers, saturated polyester resins, unsaturated polyester resins, and epoxy resins. Phenolic resin, coumarone resin, xylene resin, vinyl chloride resin, polyolefin resin and the like can be exemplified, and two or more of these resins may be used in combination. Of these resins, polyester resins are preferred.

  Examples of the mold release agent include low polar ones such as low molecular weight polyethylene, low molecular weight polypropylene, and paraffin, and high polar ones such as carnauba wax and ester. In addition, the emulsion type carboxyl group-modified polyolefin is modified so as to have a carboxyl group with an olefin unit such as ethylene, propylene, butene-1, and pentene-1 as a skeleton, and at least a part of the carboxyl group is formed with ammonia or amine. It is also possible to use neutralized polyethylene wax, polypropylene wax or the like. Of these waxes, carnauba wax is preferred.

  FIG. 1 is a view schematically showing an apparatus for producing a thread-like kneaded material for obtaining an electrophotographic toner according to the first and second embodiments of the present invention. In FIG. 1, a raw material 2 charged into a hopper 1 is melted and kneaded by an extruder 3 and supplied to a die 4. The die 4 includes a spinning port 4a and a hot air discharge port 4b. The melt-kneaded material 5 supplied to the die 4 is discharged from the spinning port 4a together with the hot air from the hot air discharge port 4b, and as a result, a thread-like kneaded material 6 is formed.

  The inner diameter of the die 4 is, for example, 100 μm, and the diameter of the yarn-like kneaded product 6 can be adjusted to 6 to 7 μm by changing the raw material supply amount, the discharge pressure, and the hot air temperature.

  At the outlet of the die 4, by blowing cold air to the thread-like kneaded product 6, the thread-like kneaded product 6 can be stably obtained without fusing the thread-like kneaded product.

  Next, the thread-like kneaded material obtained in this way is transported by the conveyor 7, cut or pulverized by a cutting machine or pulverizer (not shown), and further classified, and the electrophotographic toner according to one embodiment of the present invention. Is obtained. In the pulverization, the thread-like kneaded product already has a cross-sectional diameter corresponding to the toner particle diameter, so that the pulverization energy can be suppressed lower than that in the case of producing a normal pulverized toner. Moreover, there is little generation | occurrence | production of a fine powder and a yield and productivity improve.

  In addition to the method described above, the method for obtaining a fibrous kneaded material includes a method of drawing a fiber extruded from a die having a hole using a device such as a melt spinning device.

  As a method of pulverizing the fibrous kneaded product, a fine particle production apparatus can be used as shown in FIG. The fine particle production apparatus shown in FIG. 2 is a fine particle production apparatus for producing fine particles by cutting the thread-like kneaded product 6 into a predetermined length, and a cutting unit 11 that continuously cuts the yarn-like kneaded product 6 at regular intervals. And a conveying unit 12 that sends the yarn-like kneaded material 6 to the cutting unit 11 at a predetermined speed, and an exhaust unit 14 that creates an air flow along the conveying direction of the yarn-like kneaded material 6 at the cutting unit 11.

  FIG. 3 shows an image forming apparatus for forming an image using the electrophotographic toner according to the first and second embodiments of the present invention described above.

  The image forming apparatus shown in FIG. 3 includes a developing device 21 and a photosensitive drum 22. The developing device 21 applies a toner hopper 23 that contains toner therein, a supply roll 24 that supplies toner, and toner supplied from the supply roll 24 to the photosensitive drum 22, and electrostatic latent on the surface of the photosensitive drum 22. A developing roller 25 made of an elastic body that develops an image, and a doctor blade 26 that slides on the developing roller 25 and regulates the thickness of the toner layer on the surface of the developing roller 25 are provided. Around the photosensitive drum 22, there are a charging roll 27 for uniformly charging the surface of the photosensitive drum 22, and an LED 28 for exposing a document image to the charged surface of the photosensitive drum 22 to form an electrostatic latent image. Has been placed.

  Under the photosensitive drum 22, a transfer belt 29 runs along with the rotation of the photosensitive drum 22, and contacts the photosensitive drum 22 by the transfer sheet 30, and the developed toner image is transferred to the paper 31. The The toner that has not been transferred and remains on the surface of the photosensitive drum 22 after the transfer is removed by the cleaning blade 32.

  When the toner according to the present embodiment described above is mounted on the image forming apparatus configured as described above and the elastic developing roller is transported at a high speed of 100 mm / second or more, the toner is fused on the blade. The image uniformity is not deteriorated, and excellent durability and high image quality are achieved.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

  The test methods used in each example are as follows.

Test 1-Durability Non-magnetic one-component developing device "Casio Page Presto N-5" (manufactured by Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 horizontal) machine) and toner in a normal environment (25 ° C) , 50% RH), 10,000 sheets of 5% print images were continuously printed using plain paper (XEROX-P paper A4 size), solid images were printed, and image deterioration was evaluated. At the same time, the doctor blade was removed and the fused state of the toner on the blade was observed.

(Evaluation criteria)
A: No image deterioration is observed, and no toner fusion on the doctor blade is confirmed.

  ○: No image deterioration is observed and there is no practical problem, but toner fusion is observed on the doctor blade.

  X: Image deterioration is observed and there is a problem in practical use. Toner fusion occurred on the doctor blade.

Test 2-Low-temperature fixability Modified so that the temperature of the fixing unit portion of the same apparatus as in Test 1 can be varied to be a fixing tester. After obtaining an unfixed image with the same apparatus as in Test Example 1, the temperature is varied every 10 ° C. in the fixing temperature range of 130 to 200 ° C. with a fixing tester, and the non-fixed image is fixed. The area was measured and taken as a low-temperature fixing property. The fixing temperature here is the upper set temperature of the two fixing rolls, and the lower fixing roll has the set temperature (upper roll-20 ° C). The image pattern was solid printing, and the paper was XEROX P paper A4 size (weight 64 g / m ² ).

(Evaluation criteria)
A: The minimum fixing temperature is less than 140 ° C.

  ○: The minimum fixing temperature is 140 ° C. or higher and lower than 150 ° C.

  X: The minimum fixing temperature is 150 ° C. or higher.

Test 3-Oil-less characteristics Using the same equipment as in Test 1, remove the oil application roller on the fixing unit. A4 size (Xerox-P paper) was used as the paper, and a solid image was printed to determine the fixability. The process speed was 129.3 mm / sec and the fixing temperature was 150 ° C.

(Evaluation criteria)
A: No offset is generated.

  ○: Occurrence of offset is slight, and there is no practical problem.

  X: Level where occurrence of offset is recognized and problematic in practice.

Test 4-Image quality Non-magnetic one-component developing device "Casio Page Presto N-5" (manufactured by Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 horizontal) machine) mounted with toner in a normal environment (25 ° C, 50% RH), 10,000 sheets of 5% print images were continuously printed using plain paper (XEROX-P paper A4 size), halftone images were printed, and image uniformity was evaluated.

(Evaluation criteria)
A: Uniform halftone image without density unevenness.

  ○: Although there is some uneven density, there is no practical problem.

  X: Level in which density unevenness is observed and is problematic in practical use.

Test 5-Grindability In the pulverization classification step, the supply pressure was adjusted so that the pulverization pressure was fixed at 0.8 MPa and the volume% of particles having an average particle diameter of 6.6 μm and a particle diameter of 10 μm or more was 0.3% or less. The raw material supply amount at that time was measured and evaluated according to the evaluation criteria.

(Evaluation criteria)
◎: Supply amount is 10 kg / h or more ○: Supply amount is 5-10 kg
X: Less than 5 kg / h of supplied amount Test 6 Measurement of softening point Using a flow tester (manufactured by Shimadzu Corporation, CFT-500D), 1 g of the sample was subjected to the 1/2 method under the following conditions. The temperature at which half flowed out was taken as the softening point.

Temperature increase rate: 6 ° C / min Load: 20kg
Nozzle: 1mm diameter, 1mm length
Test 7-Measurement of glass transition point (Tg) Measured using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-60). An 8 mg sample is heated up to 200 ° C. at 10 ° C./min, cooled to 35 ° C. at a cooling rate of 10 ° C./min, and then raised again to 200 ° C. at 10 ° C./min. At the second temperature increase, the intersection of two tangents of the curve portion obtained by the transition was taken as the glass transition point.

Test 8—Measurement of Particle Size A small amount of toner, purified water, and a surfactant are placed in a beaker, and a solution sample dispersed with an ultrasonic cleaner is used with Multisizer II (manufactured by Coulter, Inc.). The particle size of was measured. The aperture was set to 100 μm, and the count was performed at 50,000 to obtain a volume average particle size.

Test 9-Molecular weight measurement The molecular weight Mn is a number average molecular weight measured by GPC (gel permeation chromatography) using a calibration curve prepared from a polystyrene sample with a known molecular weight as a standard.

Example 1
As an internal additive, a colorant C.I. 4 parts by weight of I pigment red 57: 1, 1 part by weight of charge control agent “E-84” (manufactured by Orient Chemical Co., Ltd .: salicylic acid metal complex), release agent “carnauba wax No. 1 powder” (( 5 parts by weight of imported products from Kato Yoko Co., Ltd., 10 parts by weight of cellulose (manufactured by Chisso Corporation: celluflow C-25) as a grinding aid, and 100% of a polyester resin having a softening point of 137 ° C. as a binder resin. The internal additive and the binder resin were weighed so as to be parts by weight and mixed using a Henschel mixer (Mitsui Mining Co., Ltd.).

  Next, the mixture was melt-kneaded and extruded from a die having a hole to obtain a fibrous kneaded material having a toner equivalent diameter, and then pulverized and classified to produce fine particles. The obtained fine particles had an average particle size of 6.6 μm.

  Here, when the fibrous kneaded product before pulverization is recovered as it is, it is in a state like cotton candy, and it is difficult to handle as it is to pulverize as it is. Therefore, after the fibrous kneaded material was sprayed on the mesh belt conveyor to recover the nonwoven fabric, it was crushed by a crusher. A counter-type jet mill 200-AFG (manufactured by Hosokawa / Alpine Co., Ltd.) was used as the pulverizer, and 100-TTSP (manufactured by Hosokawa / Alpine Co., Ltd.) was used as the classifier.

  As an external additive, 2 parts by weight of “R972” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) was added to 100 parts by weight of the obtained colored fine particles, and mixed with a Henschel mixer to obtain a toner.

Comparative Example 1
A toner was obtained in the same manner as in Example 1 except that cellulose was not added.

With respect to the toner according to Example 1 and Comparative Example 1, the above-described characteristics were evaluated. The results are shown in Table 1 below.

  From Table 1 above, a melt-kneaded material containing cellulose as a grinding aid was extruded from a die having a hole to obtain a fibrous kneaded material having a toner equivalent diameter, and then obtained by Example 1 obtained by pulverization and classification. The toner is excellent in durability, low-temperature fixability, oil-less property, image quality, and pulverization properties. In contrast, the toner produced by the same method as in Example 1 except that the melt-kneaded product does not contain cellulose, the toner obtained in Comparative Example 1 is excellent in low-temperature fixability and oil-less properties, and has almost the same durability and image quality. Good, but inferior in grindability.

  From the above results, it can be seen that by adding cellulose to the raw material, the grindability is improved and the durability and the image quality are improved.

Example 2
As an internal additive, a colorant C.I. 4 parts by weight of I pigment red 57: 1, 1 part by weight of charge control agent “E-84” (manufactured by Orient Chemical Co., Ltd .: salicylic acid metal complex), release agent “carnauba wax No. 1 powder” (( 5% by weight of imported products from Kato Yoko Co., Ltd., low molecular weight thermoplastic resin, 10 parts by weight of “FTR-2140” (Mitsui Chemicals, Inc .: aromatic petroleum resin), and softened as binder resin The polyester resin at a point of 137 ° C. was weighed so that the whole would be 100 parts by weight, and the internal additive and the binder resin were mixed using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.).

  Subsequently, the mixture was melt-kneaded and extruded from a die having a hole to obtain a fibrous kneaded material having a toner equivalent diameter, and then pulverized and classified to produce fine particles. The average particle size of the obtained fine particles was 6.6 μm.

  Here, when the fibrous kneaded product before pulverization is recovered as it is, it is in a state like cotton candy, and it is difficult to handle as it is to pulverize as it is. Therefore, after the fibrous kneaded material was sprayed on the mesh belt conveyor and collected in a non-woven fabric state, it was crushed by a crusher. A counter type jet mill 200-AFG (manufactured by Hosokawa / Alpine Co., Ltd.) was used as the pulverizer, and a classifier was used as 100-TTSP (manufactured by Hosokawa / Alpine Co., Ltd.).

  As an external additive, 2 parts by weight of “R972” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) was added to 100 parts by weight of the obtained colored fine particles, and mixed with a Henschel mixer to obtain a toner.

Example 3
A toner was obtained in the same manner as in Example 2 except that 30 parts by weight of “FTR-2140” (manufactured by Mitsui Chemicals, Inc .: aromatic petroleum resin) was used as the low molecular weight thermoplastic resin.

Example 4
A toner was obtained in the same manner as in Example 2 except that 5 parts by weight of “FTR-2140” (Mitsui Chemicals, Inc .: aromatic petroleum resin) was used as the low molecular weight thermoplastic resin.

Example 5
A toner was obtained in the same manner as in Example 2 except that 5 parts by weight of Fischer-Tropsch wax “Paraprint C77” (imported by Yoko Kato) was used in place of “Carnauba wax No. 1 powder” as a release agent. .

Example 6
A toner was obtained in the same manner as in Example 2 except that 10 parts by weight of “Clearon P-115” (manufactured by Yasuhara Chemical Co., Ltd .: hydrogenated terpene resin) was used as the low molecular weight thermoplastic resin.

Comparative Example 2
A toner was obtained in the same manner as in Example 2 except that no low molecular weight thermoplastic resin was added.

Comparative Example 3
A toner was obtained in the same manner as in Example 2 except that 10 parts by weight of “Alcon P-90” (manufactured by Arakawa Chemical Co., Ltd .: alicyclic saturated hydrocarbon resin) was used as the low molecular weight thermoplastic resin.

Comparative Example 4 (conventional method)
The same raw materials as in Example 2 were mixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, rolled and cooled, and coarsely pulverized with a crusher having a screen opening of 2 mm. After coarse pulverization, pulverization (200-AFG) and classification (100-TTSP) were performed, and a toner was obtained in the same manner as in Example 2.

With respect to the toners obtained in Examples 2 to 5 and Comparative Examples 2 to 4, the characteristics described above were evaluated. The results are shown in Table 2 below.

Carnauba: Carnauba wax No. 1 powder (melting point 83 ° C)
FT: Fischer-Tropsch wax (melting point 78 ° C)
From Table 2 above, as a grinding aid, a melt-kneaded product containing a predetermined low molecular weight thermoplastic resin is extruded from a die having a hole to obtain a fibrous kneaded product having a toner equivalent diameter, followed by pulverization and classification. It can be seen that the toners obtained in Examples 2 to 6 are excellent or almost good in durability, low-temperature fixability, oil-less property, image quality, and pulverization properties.

  On the other hand, the toner produced by Comparative Example 2 produced in the same manner as in Example 2, but the melt-kneaded product does not contain a low molecular weight thermoplastic resin, is excellent in low-temperature fixability and oil-less property, and durable. The image quality is also good, but the grindability is poor.

  Moreover, in the comparative example 3, since the molecular weight Mn, the softening point, and Tg of the low molecular weight thermoplastic resin were low, durability deteriorated.

  Moreover, in Comparative Example 4, the release agent content was increased in the same manner as in Examples 2 to 6, and the toner was formed by the conventional pulverization method, so the durability deteriorated.

  From the above results, it can be seen that by adding a predetermined low molecular weight thermoplastic resin to the raw material, the grindability is improved, and a great effect is also obtained in durability and high image quality.

It is a figure which shows the apparatus for obtaining the fibrous kneaded material used by one Embodiment of this invention. It is a figure which shows the apparatus for grind | pulverizing the fibrous kneaded material used in one Embodiment of this invention. 1 is a diagram illustrating an image forming apparatus for forming an image using toner obtained in an embodiment of the present invention. FIG.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Hopper, 2 ... Raw material, 3 ... Extruder, 4 ... Die, 4a ... Spinning port, 4b ... Hot-air discharge port, 5 ... Melt kneaded material, 6 ... Filamentous kneaded material, 11 ... Cutting part, 12 ... Conveying part, DESCRIPTION OF SYMBOLS 14 ... Exhaust part, 21 ... Developing device, 22 ... Photoconductor drum, 23 ... Toner hopper, 24 ... Supply roll, 25 ... Developing roll, 26 ... Doctor blade, 27 ... Charging roll, 28 ... LED, 29 ... Transfer belt, 30 ... transfer sheet, 31 ... paper, 32 ... cleaning blade.

Claims (11)

  It is manufactured by melting raw materials containing a binder resin, a colorant and a release agent, extruding from a die having a hole, forming a thread-like kneaded product having a toner equivalent diameter, and then cutting or grinding the thread-like kneaded product. An electrophotographic toner, wherein cellulose or a derivative thereof is added to the raw material as a grinding aid.   2. The electrophotographic toner according to claim 1, wherein the cellulose derivative is at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate.   The toner for electrophotography according to claim 1 or 2, wherein the cellulose or a derivative thereof has a particle size of 50 µm or less.   A toner produced by melting a raw material containing a binder resin and a colorant and extruding it from a die having a hole to form a thread-like kneaded product having a toner equivalent diameter, and then cutting or grinding the thread-like kneaded product. The number average molecular weight Mn measured by GPC is 600 to 2000, the softening point is 100 ° C. to 160 ° C., and the glass transition point Tg is 55 ° C. to 100 ° C. A toner for electrophotography characterized by adding a molecular weight thermoplastic resin.   The toner for electrophotography according to claim 4, wherein the low molecular weight thermoplastic resin is an aromatic petroleum resin.   The electrophotographic toner according to claim 1, wherein the release agent has a melting point of 70 to 100 ° C.   The electrophotographic toner according to claim 1, wherein the release agent is carnauba wax or Fischer-Tropsch wax.   The toner for electrophotography according to any one of claims 1 to 7, wherein the softening point of the binder resin is 110 to 150 ° C.   The toner for electrophotography according to claim 8, wherein the binder resin is polyester.   The toner for electrophotography according to claim 1, having an average volume particle diameter of 5 to 7 μm.   An elastic developing roller for carrying and conveying the toner; and a toner layer regulating member for regulating the thickness of the toner so as to form the toner in a thin layer on the elastic developing roller. The toner for electrophotography according to any one of claims 1 to 10, which is used in a developing device having a conveyance speed of 100 mm / second or more.

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