JPH10254172A - Electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent production of smear, offset and filming during copying by mixing a binder resin, coloring agent, polyethylene wax, polypropylene wax, etc., kneading the mixture, pulverizing, classifying to obtain particles, and then subjecting the particles to surface treatment by heat. SOLUTION: A mixture comprising at least a binder resin, coloring agent, polyethylene wax and polypropylene wax is kneaded, pulverized and classified to obtain particles, and the particles are subjected to surface treatment by heat. As for the polyethylene wax, a wax having 120 to 145 deg.C softening point is preferable. As for the polypropylene wax, a wax having 140 to 155 deg.C softening point is preferable. The sum amt. of the polyethylene wax and polypropylene wax added is 2 to 10 pts.wt., preferably 3 to 8 pts.wt. to 100 pts.wt. of the binder resin. As for the binder resin, any of styrene copolymer resin and polyester resin can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner for developing electrostatic images.

[0002]

2. Description of the Related Art As a fixing method for an image forming apparatus such as an electrophotographic apparatus, a pressure fixing method, a non-contact heat fixing method such as flash fixing and open fixing, and a contact heat fixing method such as a heat roll fixing method are employed. I have. In particular, the contact heat fixing method can be operated at a higher speed than the pressure fixing method, and has a higher thermal efficiency than the non-contact heat fixing method, and can use a relatively low-temperature heat source to reduce the size of the apparatus and save energy. Therefore, it is the most popular fixing method.

In recent years, such a contact heating fixing type electrophotographic apparatus has been required to have higher speed and energy saving. Therefore, low-temperature fixing characteristics are required for the toner. If low-temperature fixing is realized, not only energy saving of the electrophotographic apparatus can be achieved, but also warm-up time can be shortened, and more comfortable operability can be obtained.

In such a contact heating fixing system,
For example, when fixing by the hot roll fixing method, a part of the toner constituting the image is transferred to the surface of the hot roll, which is transferred again to the next transfer paper to cause an offset phenomenon that contaminates the image. Had become. As a technique for preventing the offset phenomenon, for example, a technique is known in which a polypropylene wax is added to a toner as an offset preventing agent (release agent) (for example, Japanese Patent Application Laid-Open No. 49-65231).
Publication).

In recent years, as the copying speed of electrophotography has been increased and the functions thereof have been increased, a copying machine equipped with an automatic document feeder and a duplex copying machine has become a standard. When the original is fed by these devices, or in the second copying process of backside copying or multicolor copying, the surface of the copied image is rubbed by a roller at the time of paper feeding, causing problems such as blurring and dirt on the image. I have. A similar phenomenon is observed when a plurality of copied images are temporarily stored in a copying machine by superimposing them one by one by a paper feed roller for the second copy, and the image quality is degraded. It is said that toner having such a problem has poor smear property. As a method for improving the smearing property, it is effective to add a polyethylene wax to the toner (see, for example,
-313762) is known.

However, when the above-mentioned polypropylene wax and polyethylene wax are used in combination to simultaneously improve the offset property and the smear property, a new problem occurs that filming occurs and the fluidity and chargeability of the toner decrease. doing. This is because the combined use of polyethylene wax and polypropylene wax further worsens the compatibility of these with the binder resin, and wax, especially polyethylene wax, is liberated. As a result, the free wax adheres to the photoreceptor and filming occurs. And
Further, it is considered that the fluidity and the chargeability of the toner deteriorate. With respect to such a free wax, those having a relatively large particle diameter can be removed by classification, but those having a small particle diameter cannot be removed even if classified, which is a more serious problem.

[0007]

According to the present invention, the occurrence of smear, offset and filming during copying is prevented.
An object of the present invention is to provide a toner for developing an electrostatic image having improved chargeability and the like.

[0008]

The present invention is characterized in that particles obtained by kneading, pulverizing and classifying a mixture comprising at least a binder resin, a colorant, a polyethylene wax and a polypropylene wax are subjected to a surface treatment by heat. And an electrostatic image developing toner.

The present invention is further characterized in that particles obtained by kneading, pulverizing and classifying a mixture comprising at least a binder resin, a colorant, polyethylene wax and polypropylene wax are subjected to a surface treatment by mechanical impact. And a toner for developing an electrostatic image.

The toner of the present invention comprises polyethylene wax,
It consists of a polypropylene wax, a binder resin and a colorant.

The polyethylene wax used in the present invention has a softening point of 100 to 150 ° C., preferably 110 to 145.
C, more preferably in the range of 120 to 140C. If the softening point of the polyethylene wax is lower than 100 ° C., heat resistance is poor, and filming is likely to occur,
Conversely, if the temperature is higher than 150 ° C., the smearing property is reduced. Either high-density or low-density polyethylene wax may be used, but high-density polyethylene is preferably used from the viewpoint of improving smearing properties.

Further, as the polyethylene wax, a vinyl monomer graft polyethylene may be used. This is a polyethylene obtained by graft polymerization of a vinyl monomer, which is obtained by thermal decomposition of high-pressure polyethylene, a high-pressure polymerized polyethylene wax obtained by radical polymerization of ethylene at high pressure, and further ethylene or ethylene and propylene, Α such as 1-butene, 1-hexene, 4-methyl-1-pentene, 1-decene
-It is obtained by medium / low pressure polymerization of an olefin with a transition metal compound catalyst.

The vinyl-based monomer-grafted polyethylene wax is not only excellent in compatibility with a binder resin such as a styrene-based polymer, but also is compatible with various additives such as pigments and dyes, charge control agents, plasticizers and the like. Excellent in solubility and affinity. Therefore, it also has the effect of increasing the dispersibility in these binder resins, increasing the physical uniformity of the toner such as charge controllability, and improving the performance as a developer.

The polypropylene wax used in the present invention has a softening point of 130 to 160 ° C., preferably 140 to 15 ° C.
5 ° C, more preferably 145 to 155 ° C, is suitable.
When the softening point is lower than 130 ° C., not only the heat resistance decreases, but also filming easily occurs. On the other hand, when the temperature is higher than 160 ° C., the offset property decreases. Polypropylene wax higher than the softening point of the polyethylene wax used in combination,
Preferably, by using one having a difference of 25 ° C. or less, high-temperature offset is effectively prevented.

The total amount of polyethylene wax and polypropylene wax added is 2 to 10 parts by weight, more preferably 3 to 8 parts by weight, based on 100 parts by weight of the binder resin. If the total amount of the polyethylene wax and the polypropylene wax is less than this, the offset property and smearing property decrease, and if the total amount is too large, the fluidity of the toner deteriorates and filming easily occurs.

Of these, the addition weight ratio of polypropylene wax to polyethylene wax is from 10: 1 to 1:10.
And preferably 10: 1 to 1: 1, more preferably 10: 1 to 1.2: 1. If the weight ratio of the polyethylene wax is less than this, the smear is reduced, and if it is too large, the offset property is apt to be reduced.

Although the waxes used in the present invention are mainly composed of polyethylene and polypropylene, other waxes generally used in toners, such as carnauba wax, sasol wax and rice wax, may be used in the present invention. You may use it in the range which does not harm a purpose.

As the binder resin which can be used in the present invention, styrene copolymer resins, polyester resins, epoxy resins and the like which have been conventionally used as binder resins for toner can be used. In general, the chargeability of the toner can be adjusted by any of positive or negative charge control agents described below.
In the production of a positively chargeable toner, a styrene copolymer resin is used, and in the production of a negatively chargeable toner, a polyester resin, a styrene copolymer resin, an epoxy resin, or the like is often used. Styrene-based copolymer resins are effective in producing positively and negatively chargeable toners.

These binder resins have a number average molecular weight distribution measured by gel permeation chromatography in a range of at least 2,000 to 10,000,
More preferably, the weight average molecular weight / number average molecular weight is in the range of 20 to 90, and more preferably 25 to 80.

If the number average molecular weight is less than 2,000, the heat resistance is reduced or offset tends to occur, and the number average molecular weight is reduced to 10,000.
Exceeding the range lowers the fixing strength. The weight average molecular weight /
When the ratio of the number average molecular weight is less than 20, the offset property is lowered, and when it is more than 90, the fixing strength is apt to be deteriorated.

Further, the binder resin used in the present invention has a softening point of 100 to 150 ° C., preferably 110 to 150 ° C.
A temperature of 40 ° C, more preferably 115 to 130 ° C, is desirable from the viewpoint of offset resistance and fixing strength. In addition,
The softening point was measured using a flow tester (CFT-500: manufactured by Shimadzu Corporation) and the pores of the die (diameter 1 mm, length 1 mm),
The temperature is equivalent to half the height from the outflow start point to the outflow end point when a 1 cm ³ sample is melted out under the conditions of a pressure of 20 kg / cm ² and a temperature rising rate of 6 ° C./min.

Among the binder resins described above, styrene copolymer resins are particularly preferred since they can achieve the object of the present invention more effectively. Examples of the styrene monomer constituting the styrene copolymer resin include styrene monomers such as styrene, α-methylstyrene, p-methylstyrene, p-tert-butylstyrene, and p-chlorostyrene. Its derivatives can be used.

The monomers to be copolymerized with the styrene monomer include methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and methacrylic acid. n-pentyl, isopentyl methacrylate, neopentyl methacrylate, 3-methacrylic acid
(Methyl) butyl, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate,
Methacrylic acid alkyl esters such as undecyl methacrylate and dodecyl methacrylate; methyl acrylate,
N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, neopentyl acrylate, 3-acrylic acid
(Methyl) butyl, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate and dodecyl acrylate; alkyl acrylates; unsaturated such as acrylic acid, methacrylic acid, itaconic acid and maleic acid Carboxylic acid; using vinyl monomers such as acrylonitrile, maleic ester, itaconic ester, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ethyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether be able to. Preferred are methacrylic acid alkyl esters (alkyl group having 1 to 17 carbon atoms) and acrylic acid alkyl esters (alkyl group having 1 to 17 carbon atoms).

An acid value may be given to the binder resin in order to improve the dispersibility of the polyethylene wax, the polypropylene wax, the colorant and the like. For example, when using a styrene-based copolymer resin as the binder resin, the acid value is controlled by adjusting the amount of the unsaturated carboxylic acid such as (meth) acrylic acid to be contained in the styrene-based copolymer resin, and The value is from 1 to 30 KOH mg / g, preferably from 3 to
10 KOH mg / g is appropriate.

The colorant used in the present invention is not particularly limited, and a colorant conventionally used in electrophotography can be used, and examples thereof include the following. As the black pigment, carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, ferrite, magnetite and the like can be used. As yellow pigments, yellow lead, zinc yellow, cadmium yellow, yellow iron oxide,
Mineral fast yellow, nickel titanium yellow,
Navels Yellow, Naphthol Yellow S, Banza Yellow G, Banza Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake and the like can be used.

Examples of the red pigment include red lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indaslen brilliant orange RK, benzidine orange G, indaslen brilliant orange GK, bengala, cadmium red, red lead, permanent Red 4R, Risor Red,
Pyrazolone red, watching red, lake red C, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake,
Brilliant Carmine 3B, permanent orange GT
R, Vulcan Fast Orange GG, Permanent Red F4RH, Permanent Carmine FB and the like can be used. Blue pigments include navy blue, cobalt blue, alkaline blue lake, Victoria blue lake,
Phthalocyanine blue or the like can be used. In addition, although the addition amount of these coloring agents is not particularly limited,
Usually, 1 to 100 parts by weight of resin in toner
20 parts by weight, preferably 3 to 15 parts by weight.

The toner of the present invention may contain other additives, and may appropriately contain a charge controlling agent, magnetic powder and the like.

As the charge control agent, a positive charge control agent can be used when the positive charge control of the toner is desired, and a negative charge control agent can be used when the negative charge control of the toner is desired. Examples of the positive charge control agent that can be used in the present invention include a nigrosine dye, a triphenylmethane compound, a quaternary ammonium salt compound, and the like. Examples of triphenylmethane compounds include, for example, JP-A-51-11455, JP-A-59-100457, and JP-A-61-12495.
Compounds described in, for example, Japanese Patent Publication No. 5 can be used. As the quaternary ammonium salt compound, for example, compounds described in JP-A-4-70849 or the like can be used. Salicylic acid metal complex as a negative charge control agent,
Examples include gold-containing azo dyes, calixarene compounds, and boron-containing compounds. The charge control agent may be used alone or
Although it is possible to mix and use more than one kind, it is preferable to add 0.5 to 10 parts by weight based on 100 parts by weight of the binder resin.

As the magnetic powder, ferrite, magnetite and iron powder can be used alone or in combination. The inclusion of the magnetic powder can more effectively prevent filming, scattering of toner due to magnetic force, and erosion.

The BET specific surface area is from ² to 15 m ² in order to prevent a decrease in the charging property due to poor dispersion of the magnetic powder in the toner.
/ G, preferably 5 to 12 m ² / g.

The amount of the magnetic powder used in the present invention is 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight based on 100 parts by weight of the binder resin. If the amount is more than 20 parts by weight, the image density is reduced due to a decrease in developability.

The toner for developing an electrostatic charge image of the present invention
The toner particles are obtained by a known kneading and pulverizing method. In the present invention, the obtained toner particles are further subjected to surface treatment by heat or mechanical impact. Specifically, a mixture comprising at least the binder resin as described above, a colorant, a polyethylene wax and a polypropylene wax, and optionally a charge control agent, and additives such as magnetic powder was kneaded by an extrusion kneader, and the kneaded material was cooled and solidified. After, grinding,
After classification, the volume average particle size is 5 to 14 μm, preferably 6 to 1 μm.
2 μm toner particles are obtained, the particles are subjected to a surface treatment by heat or mechanical impact, and then a fluidizing agent or a cleaning aid is added as required. In the pulverizing step, once 2 mm by a pulverizer such as a feather mill.
After coarse pulverization as described below, fine pulverization may be performed with a mechanical pulverizer to a desired particle size.

According to the present invention, the toner particles are once obtained by a conventional kneading and pulverizing method, and then subjected to a surface treatment by heat or mechanical impact force as a post-treatment, so that the particles cannot be removed in the classification step. A toner for developing an electrostatic charge image with excellent fluidity and chargeability, which does not cause smear, offset and filming at the time of copying because free wax having a small particle diameter adheres (fixes) to the toner particles. I think that the. This is due to the instantaneous melting with the toner near the surface of the toner particles when performing the surface treatment by heat, and by rubbing or driving the toner particles by the impact force when performing the surface treatment by the mechanical impact force.
It is considered that the free wax was fixed to the toner particles.

The surface treatment by heat is not particularly limited as long as it can instantaneously melt the surface of the toner particles and the free wax without causing aggregation between the toner particles. A method using a hot air flow generator capable of generating a hot air flow of, for example, a safading system (manufactured by Nippon Pneumatic). Preferably, 100 to 45
The toner particles are put into a hot air stream at 0 ° C. The treatment time depends on the melting points of the binder resin and the wax and the airflow temperature, and is appropriately set.
Seconds. When the airflow temperature is lower than 100 ° C., the effect of the present invention is hardly obtained, that is, the free wax hardly adheres (fixes) to the surface of the toner particles. Will be invited. Further, if the processing time exceeds 1 second, aggregation between toner particles is caused.

As a surface treatment method using a mechanical impact force, without causing further pulverization of the toner particles,
The method is not particularly limited as long as a physical impact can be applied to the free wax to such an extent that the free wax can be attached to the toner particles, preferably rubbed or driven into the toner particles. Machines, for example, a hybridization system (NHS-0: manufactured by Nara Machinery Co., Ltd.), mechanofusion (Angumill, manufactured by Hosokawa Micron), a super hybrid mill (IH)
I) and Kryptron system model KOSMOS
(Manufactured by Kawasaki Heavy Industries, Ltd.). It is necessary to set processing conditions to be weaker than in the case of performing pulverization using the above-described pulverizer. For example, when processing using a hybridization system (NHS-0: manufactured by Nara Machinery Co., Ltd.), 10,000 to 17000 rpm, preferably 1 to 17000 rpm.
It is desirable to perform the treatment at 2000 to 16000 rpm for 1 to 10 minutes, preferably 1 to 3 minutes. Processing time is 10
If the time is longer than minutes, aggregation between toner particles occurs. One
If the time is shorter than minutes, the adhesion becomes insufficient and the effect of the present invention cannot be obtained. When the rotation speed exceeds 17000 rpm, the generation of fine powder cannot be ignored, and it is difficult to set a processing time for obtaining the effect of the present invention, and the rotation speed is increased to 10,000.
If it is less than rpm, dispersion of toner particles and the like becomes insufficient, and desired adhesion of free wax is not performed.

Further, the toner of the present invention can be obtained by performing both of such surface treatment by heat and surface treatment by mechanical impact force. The respective processing conditions at that time need to be slightly weaker than the above conditions, and are particularly set appropriately so that aggregation between toner particles and further pulverization of the toner particles do not occur. The order of performing the surface treatment by heat and the surface treatment by mechanical impact is not particularly limited.

After the above-mentioned surface treatment, the fluidizing agent optionally added includes silica fine particles, titanium dioxide fine particles, amylna fine particles, magnesium fluoride fine particles, silicon carbide fine particles, boron carbide fine particles, titanium carbide fine particles,
Examples include zirconium carbide particles, boron nitride particles, titanium nitride particles, zirconium nitride particles, magnetite particles, molybdenum disulfide particles, aluminum stearate particles, magnesium stearate particles, and zinc stearate particles.

It is desirable that these fine particles are subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like before use.

The amount of the fluidizing agent is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the toner.

Examples of the cleaning aid include styrene, acrylic, methacrylic, benzoguanamine, silicone, Teflon and the like, which are granulated by a wet polymerization method such as emulsion polymerization, soap-free emulsion polymerization, non-aqueous dispersion polymerization, or a gas phase method. Various organic fine particles such as polyethylene and polypropylene can be used alone or in combination. The addition amount is usually 0.0 with respect to 100 parts by weight of the binder resin.
1 to 1 part by weight.

The toner of the present invention can be used in either a one-component developer using no carrier or a two-component developer used with a carrier. As the carrier used with the toner of the present invention, known carriers can be used, for example, iron powder, a carrier composed of magnetic particles such as ferrite, a coated carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, Alternatively, any of a dispersion type carrier obtained by dispersing a magnetic fine powder in a binder resin can be used. As such a carrier, those having a volume average particle size of 15 to 100 μm, preferably 20 to 80 μm are suitable.

When the toner of the present invention is used as a positively chargeable toner, a preferable carrier is:
That is, the carrier has a negatively charged resin on the surface.
Examples of such resins include polyester resins, polyolefin resins such as polyethylene, tetrafluoroethylene, vinylidene fluoride, homopolymers of fluorine-containing vinyl monomers or copolymers with other vinyl monomers. And the like. Particularly preferred is a carrier on which the above-mentioned negatively chargeable resin coating layer is formed, or a carrier obtained by dispersing magnetic fine powder in the above negatively chargeable resin, from the viewpoint of chargeability in combination with the toner of the present invention. .

When the toner of the present invention is used as a negatively chargeable toner, a carrier having a positively chargeable resin on its surface is preferable. Examples of such a resin include an acrylic resin, a styrene-acrylic resin, and a silicone resin.
The following examples illustrate the invention in more detail.

[0044]

【Example】

(Production Example of Binder Type Carrier) In order to use the toner for evaluation described below, a binder type carrier was produced as follows. Component weight part・ Polyester resin 100 (Kao Corporation: NE-1110) ・ Inorganic magnetic powder 500 (TDK: MFP-2) ・ Carbon black 2 (Mitsubishi Kasei: MA # 8)

The above-mentioned materials were sufficiently mixed and pulverized by a Henschel mixer, and then melt-kneaded using an extruder kneader set at a cylinder portion of 180 ° C. and a cylinder head portion of 170 ° C. The kneaded product was cooled, coarsely pulverized, finely pulverized with a jet mill, and further classified using an air classifier to obtain a magnetic carrier having a volume average particle size of 55 μm.

Example 1 100 parts by weight of a thermoplastic styrene-acrylic resin styrene-butyl acrylate-butyl methacrylate-methacrylic acid copolymer (monomer weight ratio = 7: 1.4: 1.4: 0.2) : Acid value 6.5 KOH mg / g) (Mn = 4000, Mw / Mn = 68.8, softening point = 121.8 ° C.) Additive for preventing offset Polypropylene wax (softening point about 145 ° C.) 3 parts by weight ( Viscol 660P, manufactured by Sanyo Chemical Co., Ltd. ・ Smear prevention additive Polyethylene wax (softening point: approx. 140 ° C.) 3 parts by weight (High Wax 800P, manufactured by Mitsui Petrochemical Co., Ltd.) ・ Carbon black (Mogal L, manufactured by Cabot Corporation) 10 parts by weight Parts-Nigrosine dye 5.0 parts by weight (Nigrosine base EX, manufactured by Orient Chemical Co.)-Quaternary ammonium salt 0.5 parts by weight (P-53, orientated)・ Magnetic powder (MFP-2, manufactured by TDK) 2 parts by weight

The above materials were mixed with a Henschel mixer (capacity 7
5l) and mixed for 3 minutes at 3000 rpm. The mixture is screw extruded kneader (TEM50: manufactured by Toshiba Machine Co., Ltd.)
The mixture was continuously extruded and kneaded under the conditions of a temperature of 120 ° C., a supply amount of 30 kg / hr, and a screw rotation speed of 150 rpm, followed by rolling with a press roller having a nip width of 1 mm and further forced water cooling on a belt cooler.

The kneaded material was coarsely pulverized with a feather mill (2 mm mesh). The coarsely pulverized material is finely pulverized to 10 μm with a mechanical pulverizer (Krypton KTM-O type, manufactured by Kawasaki Heavy Industries, Ltd.), and a jet mill (IDS) equipped with a natural air flow classifier is used.
-2 type, manufactured by Nippon Pneumatic Co., Ltd.), and fine particles are cut by a rotary rotor classifier (50ATP classifier, manufactured by Hosokawa Micron) to obtain toner particles having a volume average particle size of 8.5 μm. I got

The obtained toner particles were subjected to a surface treatment with a hot air stream of 300 ° C. for 0.5 seconds using a Suffing System (manufactured by Nippon Pneumatic), and then treated with hydrophobic silica (R-974, Nippon Aerosil). And 0.15% by weight of the toner to obtain a toner.

Examples 2 and 3, Comparative Example 2 A toner was prepared according to Example 1. However, the type and amount of the binder resin and the polypropylene wax and the type and amount of the polyethylene wax are as shown in Table 1.

Examples 4 to 6 and Comparative Example 3 The obtained toner particles were subjected to a surface treatment at 14,000 rpm for 2 minutes by mechanical impact using a hybridization system (NHS-0; manufactured by Nara Machinery Co., Ltd.). Other than the above, a toner was obtained in the same manner as in Example 1. However, the type and amount of the binder resin and the polypropylene wax and the type and amount of the polyethylene wax are as shown in Table 1.

Comparative Example 1 A toner was obtained in the same manner as in Example 1, except that the obtained toner particles were not subjected to a surface treatment. However, the type and amount of the binder resin and the polypropylene wax and the type and amount of the polyethylene wax are as shown in Table 1.

The toners obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were mixed with the binder type carrier obtained above at a weight ratio (toner / carrier) of 5/95 to obtain a developer.
The following evaluation was performed using this developer.

Evaluation method (1) Smearing property After the developer was fixed on copying paper using a copying machine (EP4050: manufactured by Minolta), another unused copy paper was used to obtain a copied image. Rub together with the formed paper,
The degree of dirt on the unused copy paper was observed and ranked as follows. ：: Almost no stain was conspicuous; Δ: Slight stain was observed but no problem in practical use; ×: Stain was observed on all paper surfaces.

(2) Offset When copying using the above-mentioned copying machine modified so that the fixing roller temperature can be changed, the fixing roller temperature is raised to around 250 ° C., and the following occurs depending on the temperature at which the offset occurs. The ranking was performed. ：: No offset occurs at 250 ° C .; Δ: No offset occurs below 250 ° C .; X: Offset occurs below 230 ° C.

(3) Filming Property After continuously copying 50,000 sheets using the above copying machine (EP4050: manufactured by Minolta), a halftone image was formed and the photosensitive member was observed. Was ranked. The fixing roller temperature was 190 ° C. ：: Both image stains and toner component adhesion to the photoreceptor are not present; Δ: Part of the photoreceptor surface is slightly hazy, but there is no disturbance of the image; ×: The entire photoreceptor is hazy and the image is It is disordered.

The above evaluation results are shown together with the manufacturing conditions in Table 1 below.

[Table 1]

In the present specification, the average particle size is measured by the following method. The average particle size of the carrier was 280 μm using a Coulter Multisizer (manufactured by Coulter).
m with an aperture tube. The average particle size of the toner was measured using the same apparatus with a 100 μm aperture tube.

[0059]

According to the present invention, it is possible to provide a toner which can prevent smear and offset at the time of copying, does not cause filming, and does not cause a decrease in fluidity or chargeability of the toner.

The continuation of the front page (72) Yoshihiro Mikuri 2-13-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Hiroshi Fukao 2-3-3 Azuchicho, Chuo-ku, Osaka-shi, Osaka No. 13 Osaka International Building Minolta Co., Ltd. (72) Inventor Fumiko Nakazawa 2-3-13 Azuchicho, Chuo-ku, Osaka City, Osaka Prefecture Osaka International Building Minolta Co., Ltd. (72) Inventor Hiroyuki Fukuda Osaka City Osaka Central Osaka International Building Minolta Co., Ltd. 2-3-13 Azuchicho, Ward

Claims (4)

[Claims] 1. An electrostatic image developing method characterized in that particles obtained by kneading, pulverizing and classifying at least a mixture comprising a binder resin, a colorant, a polyethylene wax and a polypropylene wax are subjected to a surface treatment by heat. toner. 2. An electrostatic charge characterized in that particles obtained by kneading, pulverizing and classifying at least a mixture comprising a binder resin, a colorant, a polyethylene wax and a polypropylene wax are surface-treated by mechanical impact. Image developing toner. 3. The total amount of polyethylene wax and polypropylene wax added is 2 to 10 parts by weight based on 100 parts by weight of the binder resin, and the content ratio of polypropylene wax to polyethylene wax is 10: 1 to 1 by weight.
3. The electrostatic image developing toner according to claim 1, wherein the ratio is 1:10. 4. A polypropylene wax having a softening point of 13
0 to 160 ° C., softening point of polyethylene wax is 100
The toner for developing an electrostatic image according to any one of claims 1 to 3, wherein the softening point of the polypropylene wax is higher than that of the polyethylene wax.