JPH0481771A - Electrostatic image developing toner - Google Patents

Abstract

PURPOSE:To stably form good images many times without deteriorating image quality by limiting the upper limit of the softening point of the binder resin of base material particles to improve low-temp. fixability and to sufficiently fix composite fine particles to the surface of the base material particles by mechanical impact force. CONSTITUTION:The composite fine particles formed by treating the surface of fine resin particles by inorg. fine particles are fixed by the mechanical impact to the base material particles formed by containing a thermoplastic resin having <=120 deg.C softening point as a binder resin. Then, the fixability of the composite fine particles to the surface of the base material particles is exceedingly improved and the toner securely fixed with the composite fine particles on the surfaces of the base material particles is obtd. Toner filing is effectively prevented by the composite fine particles in a developing process and the low- temp. fixability possessed by the base material particles is sufficiently exhibited without being hindered in a heat roller fixing process. The good images are thus stably formed many times without deteriorating the image quality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostatic image developing toner applied to electrophotography, electrostatic printing, electrostatic recording, etc. The present invention relates to an electrostatic image developing toner comprising composite fine particles.

[Conventional technology]

In one example of electrophotography, an electrostatic image is formed on a photoconductive photoreceptor by charging and exposure, and this electrostatic image is developed with toner to form a toner image.

As the toner image fixing means, a heated roller fixing system is preferably used because it has high thermal efficiency and can perform high-speed fixing.

Particularly in recent years, there has been a demand for toners that can be fixed with sufficient strength even when the set temperature of the heat roller is lowered, that is, toners that have excellent low-temperature fixability. This is to prevent thermal deterioration of the photoreceptor, to shorten the warm-up time required for the heat roller to rise to a temperature that can be fixed after the fuser is activated, and to prevent heat from being absorbed by the transfer paper. This is due to the need to reduce the temperature drop of the heat roller due to the above-mentioned problems, thereby making it possible to perform continuous copying many times, and to prevent failures in the conveyance system due to curling of the transfer paper.

However, in order to improve the low-temperature fixability of the toner, it is effective to use a binder resin with a low softening point as the toner binder resin.

However, when a binder resin with a low softening point is used, toner aggregation occurs and the stability as a powder is impaired. Furthermore, toner filming occurs on the surface of the photoreceptor or developing sleeve, which deteriorates the surface characteristics of the photoreceptor. Furthermore, toner substances adhere to the surface of the carrier, deteriorating the triboelectric charging properties of the carrier.

Therefore, in the past, the following techniques have been proposed.

(1) Embedded resin fine particles on the surface of the base particle that have a softening point higher than that of the base particle and have an average particle size of 0.1 μm or more and 1/4 or less of the average particle size of the base particle. Technology of coating toner
Publication No. 9).

(2) Fine resin particles with a glass transition point of 50°C or higher are attached to the surface of base particles with a Brinell hardness of 30 or less, and a mechanical impact force is applied to the fine resin particles to hold them on the surface of the base particles. Technology for composing toner (Unexamined Japanese Patent Publication No. 1993-10
5261).

(3) A technique in which a toner is constituted by base particles and composite fine particles made of fine resin particles whose surface has been treated with inorganic fine particles (Japanese Patent Laid-Open No. 64-91143).

[Problem to be solved by the invention]

In the techniques (1) and (2) above, a resin with excellent low-temperature fixing properties is used as the base particle, and the surface of the base particle is coated with fine resin particles having a higher softening point or glass transition point. Although it is a toner, if the surface of the base particle is completely covered with the resin fine particles, low-temperature fixing properties and anti-offset properties will deteriorate, so it is necessary to expose a part of the surface of the base particle. However, if a part of the surface of the base particles is exposed, toner filming, in which the surface of the photoconductor or developing sleeve is likely to be filmed by the constituent components of the base particles, may occur, and the surface of the carrier may be exposed to the surface of the base particles. There are problems that can arise if the toner spent is contaminated by the components.

This problem is particularly important for medium- and high-speed machines with high line speeds (
This becomes noticeable at line speeds of 200 mm/sec or higher.

Further, in the technique (3) above, by using composite fine particles made of fine resin particles whose surface has been treated with inorganic fine particles, it is possible to appropriately polish a substance filmed on a photoreceptor or the like. However, if the base particles contain a binder resin or wax with a low softening point in order to improve low-temperature fixing properties, the amount of filming material will inevitably increase, and therefore, in order to polish it, the amount of composite fine particles added must be It is necessary to increase the number of However, when the amount of composite fine particles added is increased, more composite fine particles are released from the base particles and transferred and adhered to the developing sleeve or carrier, which causes a problem that the triboelectric charging property of the carrier deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner for electrostatic image development that exhibits excellent low-temperature fixability and is less likely to cause toner filming.

[Means to solve the problem]

In order to achieve the above objectives, the inventors of the present invention have conducted intensive research and have selected a thermoplastic resin with a low softening point of 120"C or less as the binder resin for the base particles to ensure the low-temperature fixability of the toner. However, the present inventors have discovered that toner filming caused by the binder resin of the base particles can be effectively prevented by fixing the composite fine particles to the surface of the base particles using a mechanical impact force, leading to the completion of the present invention. It is something.

Therefore, the electrostatic image developing toner of the present invention has a softening point of 12
It is characterized in that composite fine particles whose surfaces are treated with inorganic fine particles are fixed to base particles containing a thermoplastic resin of 0° C. or lower as a binder resin by mechanical impact force.

In this way, in the present invention, since the upper limit of the softening point of the binder resin of the base particles is defined as 120''C, when the base particles and the composite fine particles are mixed and a mechanical impact force is applied to them, The surface of the base particle is thermally softened, making it easier for the composite fine particles to fuse to the surface, and the adhesion of the composite fine particle to the surface of the base particle is greatly improved, allowing the composite fine particle to firmly adhere to the surface of the base particle. You can obtain a toner that is

Therefore, in the development process, toner filming is effectively prevented by the composite fine particles, and in the heat roller fixing process, the low-temperature fixing properties of the base particles are fully exhibited without being inhibited. As a result, it becomes possible to stably form a good image many times without causing deterioration in image quality.

Hereinafter, the configuration of the present invention will be specifically explained.

In the present invention, as the binder resin of the base particles,
A thermoplastic resin having a softening point Tsp of 120° C. or lower is used.

If the softening point Tsp is 120° C. or less, the composite fine particles are easily fixed to the base particles, and excellent low-temperature fixing properties are exhibited in a hot roller fixing process.

On the other hand, the softening point Ts of the binder resin of the base particles
If p is higher than 120° C., it becomes difficult to fix the composite fine particles, and sufficient low-temperature fixability is not exhibited.

Here, the softening point Tsp is determined by the "Koka Type Flow Tester" (
(manufactured by Shimabara Seisakusho). Specifically, a 1 cm' sample was heated at a heating rate of 6°C/min, and then a plunger was used to apply a load of 20 kg/cm2.
As if pushing out a nozzle with a diameter of 1 mm and a length of 1 mm, draw a flow tester's plunger drop amount-temperature curve (softening flow curve), and when the height of the S-shaped curve is h, it corresponds to h/2. The temperature was defined as the softening point Tsp.

As a thermoplastic resin with a softening point Tsp of 120°C or less,
It can be appropriately selected from styrene resins, acrylic resins, styrene-acrylic copolymer resins, polyester resins, epoxy resins, and the like.

In particular, in the present invention, a block copolymer or graft copolymer of a crystalline polymer and an amorphous polymer having a functional group bonded thereto, as described in JP-A No. 63-27855, is used. A copolymer can be preferably used as a binder resin for the base particles.

In addition to the binder resin, the base particles may contain other toner components such as a colorant, a charge control agent, a wax, and a magnetic material, if necessary.

Colorants include carbon black, chrome yellow,
DuPont oil red, quinoline yellow, phthalocyanine blue, malachite green offsalate, etc. can be used.

As the charge control agent, nigrosine dyes, metal-containing azo dyes, metal complexes, etc. can be used.

As the wax, low molecular weight polyolefin wax such as polyethylene or polypropylene, paraffin wax, ester wax, Ami-F wax, etc. can be used.

As the magnetic material, ferrite, magnetite, iron, cobalt, nickel, and other ferromagnetic metals or alloys, or compounds containing these elements can be used. This magnetic material is used when obtaining magnetic toner.

Composite fine particles are resin fine particles whose surfaces are treated with inorganic fine particles.

Materials for inorganic fine particles include silicon oxide, aluminum oxide, titanium oxide, zinc oxide, zirconia oxide, chromium oxide, cerium oxide, tungsten oxide, antimony oxide, steel oxide, tin oxide, tellurium oxide, manganese oxide,
Oxides such as boron oxide, barium titanate, aluminum titanate, magnesium titanate, calcium titanate, strontium titanate, ■ carbides such as silicon carbide, tungsten carbide, boron carbide, titanium carbide, ■ silicon nitride, titanium nitride, Nitride such as boron nitride, etc. can be used.

The primary particle size of the inorganic fine particles is preferably smaller than the particle size of the resin fine particles, particularly 1/1 of the particle size of the resin fine particles.
It is preferably 2 or less. Specifically, 0.01-
A range of 0.1 μm is preferable. Note that the primary particle diameter of the inorganic fine particles was measured by observation using a SEM.

If the primary particle diameter of the inorganic fine particles is within this range, the toner cleaning properties will be improved, and a suitable polishing action will be exhibited, and the deteriorated parts or toner filming parts on the surface of the photoreceptor will be well polished and exposed. Body surface properties are maintained stably over a long period of time. Note that when the primary particle size of the inorganic fine particles is too large, it is likely to be difficult to make them adhere to the surface of the resin fine particles. In addition, when the primary particle size of inorganic fine particles is too small, they tend to be buried in inorganic fine particles or resin fine particles.
Cleanability tends to deteriorate.

The amount of inorganic fine particles used is 0.01 based on the entire toner.
A range of 5% by weight is preferable, and a range of 0.05 to 2% by weight is particularly preferable.

The fine resin particles constituting the composite fine particles are preferably vinyl polymer particles. Specifically, styrene resin, acrylic resin, styrene/acrylic resin, etc. can be preferably used.

Styrenic monomers used to obtain these resins include:
Styrene, 0-methylstyrene, m-methylstyrene,
p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-t-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, etc. can be used.

In addition, acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, acrylic Acrylic acid or its esters such as 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate Methacrylates such as n-butyl acid, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. Acids or their esters can be used.

The above monomers may be used alone or in combination. For example, methyl methacrylate/n-butyl acrylate/styrene copolymer and the like can be preferably used.

The vinyl polymer preferably has a softening point higher than the softening point of the binder resin of the base particles and has a softening point of 160° C. or lower. By using a vinyl polymer having a softening point within this range, the cleaning performance and toner filming prevention effect can be further improved without impairing the low-temperature fixing properties and anti-offset properties of the toner.

Moreover, it is preferable that the glass transition point Tg of the vinyl polymer is 55° C. or higher. If Tg is 55°C or higher, blocking resistance will be good.

Here, Tg is measured based on differential scanning calorimetry (DSC). Specifically, rDSC-2
0" (manufactured by Seiko Electronics Industries, Ltd.) at a heating rate of 10
When measured at °C/min, the temperature at the intersection of the extension line of the baseline below the glass transition temperature and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak was defined as the glass transition point. .

The average particle diameter (-order particles) of the resin fine particles is 0.02 to 0.
A range of 6 μm is preferable. If the average particle size is within this range, the adhesion of the composite fine particles to the base particles will further increase.

The composite fine particles are surface-treated with the above resin fine particles or the above inorganic fine particles.

Here, the surface treatment may be a process in which the inorganic particles are simply attached to the surface of the resin particles by electrostatic force, or it may be a process in which the inorganic particles are fixed to the surface of the resin particles instead of simply being attached by electrostatic force. good.

In addition, even if the inorganic fine particles in the composite fine particles are simply attached to the resin fine particles due to electrostatic force, when the composite fine particles are fixed to the resin fine particles by mechanical impact force, the inorganic fine particles may be attached due to the electrostatic force. The inorganic fine particles become fixed to the resin fine particles.

Methods for fixing inorganic particles to the surface of resin particles include a method of mixing inorganic particles and resin particles and then applying heat, a mechanochemical method of fixing inorganic particles to the surface of resin particles by mechanical impact force, etc. It is possible to use

Specifically, the following method can be applied.

■ Mix resin particles and inorganic particles, stir and mix using a Henschel mixer, V-type mixer, turbular mixer, etc., make the inorganic particles adhere to the surface of the resin particles by electrostatic force, and then attach the inorganic particles to the surface. A method in which the resin particles are introduced into a heat treatment device such as a Niro atomizer or a spray dryer, and heat is applied to soften the surface of the resin particles, thereby fixing the inorganic particles to the surface.

■ After attaching the inorganic particles to the surface of the resin particles using electrostatic force, use a device that can apply mechanical energy, such as an ONG mill, a free mill, or a hybridizer, to attach the inorganic particles to the surface of the resin particles. A method of fixing fine particles.

When obtaining composite fine particles, the amount of inorganic fine particles blended with respect to the resin fine particles may be an amount that covers 10 to 100% of the surface of the resin fine particles.

Specifically, the inorganic fine particles are usually used at a ratio of 5 to 60% by weight, preferably 5 to 40% by weight, based on the resin fine particles, depending on the particle size and specific gravity of the inorganic fine particles.

On the other hand, if the proportion of inorganic fine particles is too small, the cleaning performance tends to deteriorate, and conversely, if the proportion of inorganic fine particles is too large, the inorganic fine particles tend to be liberated, resulting in a decrease in durability.

In the present invention, whether it is necessary to fix the composite fine particles to the base particles by mechanical impact force, and "fixing"
A state in which the height of the composite fine particle portion protruding from the surface of the base particle is 5 to 95% of the diameter of the composite fine particle. Note that such a state can be easily confirmed by observing the surface of the toner particles using a transmission electron microscope or an ordinary electron microscope.

The blending amount of the composite fine particles to be fixed is 10 to 10% on the surface of the base particle.
An amount that provides 90% coverage is preferred.

In order to obtain such a state, in a system where base particles and composite fine particles exist together, an impact force of a magnitude that does not crush the base particles, for example, 115 to 1/10 of the force normally required for crushing, is required. It is sufficient to apply a mechanical impact force of 300 degrees. Specifically, although it varies depending on the characteristics of the binder resin contained in the base particles, 1
．． 59X]0-' to 9.56X10-'erg, preferably 1.20X10-' to 1.60X10-
'erg's mechanical impact force may be applied.

As a device for applying such a mechanical impact force, a super mill, a ball mill, a hybridizer, etc. can be used.

Fig. 1 shows an example of a hybridizer, in which 1 is a powder input valve, 2 is a powder input chute, 3 is a circulation circuit, 4 is a casing, 5 is a rotary disk, 6 is a blade, 7 is a stator, 8 is a
9 is a powder discharge chute, and 10 is a powder discharge valve. Note that the arrow represents the locus of the powder.

When the rotary disk 5 having blades 6 is rotated at high speed, centrifugal force is applied to the internal air by the blades 6, and the rotary disk 5
The outside of the rotary disk 5 is pressurized, and the center of the rotary disk 5 is under negative pressure.

Since the outside and center of the rotary disk 5 are connected by the circulation circuit 3, the pressurized air outside the rotary disk 5 moves through the circulation circuit 3 to the center of the rotary disk 5, and air A circulating flow is formed.

In a state where such a circulating flow of air is formed, from the powder input chute 2 provided in the middle of the circulation circuit 3,
When a mixture of base particles and composite fine particles is introduced, the mixture begins to circulate through the circulation circuit 3 along with this circulation flow, and during this circulation process, the mixture collides with the blade 6 and receives a mechanical impact force. As a result, the composite fine particles are fixed to the surface of the base particles. After this circulation process has been carried out for a certain period of time, the powder discharge valve IO is opened and the treated material is discharged by centrifugal force, thereby obtaining treated particles in which the composite fine particles are firmly fixed to the surface of the base particles.

In such a circulation process, the circulation circuit 3 and the powder discharge chute 9 may be cooled or heated by the jacket 8 provided on the stator 7 side in order to control the temperature inside the apparatus.

In the second hybridizer, the circumferential speed of the rotary disk 5 is 50
The range of ~80m/sec is preferable, and the product temperature is 20~60m/sec.
It is preferable that the temperature is in the range of .degree. C., and the treatment time is preferably in the range of 3 to 10 minutes.

In the present invention, external additives may be further added to the toner obtained as described above.

External additives include fine particles such as silica, alumina, titania, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide, and silicon nitride. Can be used. Among them, silica fine particles are preferred. The amount of these fine particles to be used is preferably 0.01 to 5% by weight of the entire toner, particularly 0.01 to 5% by weight of the entire toner.
．． 05-2% by weight is preferred.

Other lubricants include zinc stearate, aluminum stearate, lithium stearate, stearic acid,
Hydrogenated castor oil and the like may also be added to the toner. The amount of lubricant used is preferably 0.01 to 2% by weight of the entire toner.

These external additives may be added and mixed together with the composite fine particles, or may be added and mixed after the composite fine particles are fixed.

The toner of the present invention may be mixed with a carrier and used as a two-component developer, or may be used as a one-component developer without being mixed with a carrier.

As the carrier constituting the two-component developer, conventionally known carriers can be used. Specifically, the surfaces of particles of ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite are coated with 2°2,2-trifluoroethyl methacrylate, etc. A carrier coated with a fluororesin, a silicone resin, a styrene/acrylic resin, or the like can be preferably used.

The average particle diameter of the carrier is preferably in the range of 20 to 200 μm, particularly preferably in the range of 30 to 150 μm.

〔Example〕

Examples of the present invention will be described below along with comparative examples, but the embodiments of the present invention are not limited to these Examples.

In addition, in the following, "parts" represent "parts by weight".

Further, St represents styrene, n-BA represents n-butyl acrylate, and MMA represents methyl methacrylate.

<Material particle A> Binder resin----1・---------------------
-100 parts (St/n-BA copolymer, Tsp: 11
5℃）Carbon black −−・−・・−−−−−・−
・・ 10 parts (made by Mogul, manufactured by Capot) Paraffin wax -・−・−・・−・・−・・−・
3 parts (Sasol Wax H1, manufactured by Sasol Market Soting Co., Ltd.) Alkylene bis fatty acid amide -----1---...
Three parts (Hoechst Wax C, manufactured by Hoechst) or more of the materials were mixed, melted and kneaded using heated rolls, cooled, crushed, and classified using an air classifier to obtain base particles A with an average particle size of 11 μm. .

Base Particle B> In the production of base particle A, the binder resin is S t
/n-B A/MMA/acrylic acid copolymer,
Graft copolymer with polyhexamethylene sebacate (
Base particles B were obtained in the same manner except that the temperature was changed to Tsp: 110°C).

<Base particle C> Binder resin ・ −・−・・−−1−−・−−6
0 parts (graft copolymer same as base particle B) Magnetite ・・・−−−−・・−−1−−・−・・−−1・
-35 parts (BL-100, manufactured by Titan Kogyo Co., Ltd.) Wax - - - - - - - - - 3 parts (low molecular weight polypropylene, Viscol 660P.

Sanyo Chemical Industries, Ltd.) Charge control agent −・・−・・−・・−・・−・−・・−・
... 2 parts (Bontron E-82, manufactured by Orient Chemical Industry Co., Ltd.) or more of the materials are mixed, melted and kneaded using heated rolls, cooled, crushed, and classified using an air classifier to form a matrix with an average particle size of 11 μm. Particles C were obtained.

Base particle a> In the production of base particle A, the binder resin is S t
/n-B A/MMA copolymer (Tsp: 1
Comparative base particles a were obtained in the same manner except that the temperature was changed to 35°C).

<Resin fine particles l> MMA/n-BA/S copolymer (weight ratio: 40/2
0/40) and having an average particle diameter of 0.4 μm are referred to as resin fine particles 1. The Tsp of this resin fine particle 1 is 140
°C, Tg was 60 °C.

<Resin fine particles 2> MMA/n-BA/St copolymer (weight ratio: 40/20
/40) with an average particle diameter of 0.25 μm will be referred to as resin fine particles 2. The Tsp of this resin fine particle 2 is 142
°C, Tg was 61 °C.

<Inorganic Fine Particles 1> Inorganic Fine Particles 1 are fine particles made of titanium oxide and having an average particle diameter of 0.03 μm.

<Inorganic Fine Particles 2> Inorganic fine particles 2 are particles made of silicon carbide and having an average particle diameter of 0.05 μm.

<Composite Fine Particles 1> Resin Fine Particles 1 60 parts Inorganic Fine Particles 1 40 parts or more of the materials were thoroughly stirred and mixed using a V-type mixer, and the inorganic fine particles were attached to the surface of the resin fine particles by electrostatic force.

Next, these were transferred to [Nara Hybridization System NH3-IJ (manufactured by Nara Kikai Seisakusho), and the rotation speed of the impact blade was set to 5.000 rpm, and the peripheral speed was set to 62.5 m/min.
see, and mechanical impact force was applied for 5 minutes to obtain composite fine particles 1 in which inorganic fine particles were fixed to the surface of resin fine particles.

Composite fine particles 2> Resin fine particles 2 55 parts Inorganic fine particles 1 45 parts or more of the materials are thoroughly stirred and mixed using a V-type mixer, and the inorganic fine particles are attached to the surface of the resin fine particles by electrostatic force to obtain composite fine particles 2. Obtained.

<Composite fine particles 3> Resin fine particles 2 70 parts Inorganic fine particles 2 30 parts or more of the materials are thoroughly stirred and mixed using a V-type mixer, and the inorganic fine particles are attached to the surface of the resin fine particles by electrostatic force.Composite fine particles 3
I got it.

<Example 1> Base particle A...-----1------...----
・・・−・−・・・・ 95 parts Composite fine particles 1−・−
・−−−−・−・・−・−−−−−・−・ 5 parts or more of the materials were sufficiently stirred and mixed using a V-type mixer, and the composite fine particles were attached to the base particles by electrostatic force.

Next, these were transferred to the Nara Hybridization System NH3-IJ (manufactured by Nara Kikai Seisakusho), and the rotation speed of the impact blade was set to 6.00 Orpm, and the peripheral speed was set to 75 m/s.
ee and applied mechanical impact force for 5 minutes.
Treated particles were obtained by adhering composite fine particles to the surface of base particles. Note that the product temperature at this time was 40°C.

Silica fine particles (hereinafter referred to as "
"Surface-treated silica particles." ) and 0.1 part of zinc stearate were added and mixed using a V-type mixer to obtain Toner 1 of the present invention.

Surface observation using a scanning electron microscope and transmission electron II microscope revealed that the toner l was either a composite fine particle that had been attached to the surface of the base particle by electrostatic force, or was in a state that was firmly fixed to the surface of the base particle. It was recognized that

<Example 2> Base particle B------------97
Part composite fine particles I -...-1----1--
- Treated particles were obtained in the same manner as in Example 1 using -3 parts or more of the material.

Toner 2 of the present invention was obtained by adding and mixing surface-treated silica fine particles and zinc stearate to the treated particles in the same manner as in Example 1.

<Example 3> Base particle B---------・・−・−・・−・・・・・・・
−・・・・・・・ 97 parts Composite fine particles 2 −−−−・・−
----------------------- Treated particles were obtained in the same manner as in Example 1 using 3 parts or more of the material.

Toner 3 of the present invention was obtained by adding and mixing surface-treated silica fine particles and zinc stearate to the treated particles in the same manner as in Example 1.

Surface observation using a scanning electron microscope and transmission electron microscope revealed that in this toner 3, not only the composite fine particles on the surface of the base particles but also the inorganic fine particles attached to the surface of the resin fine particles due to electrostatic force were It was observed that the material was firmly adhered to the surface of the material.

<Example 4> Base particle B.
Treated particles were obtained in the same manner as in Example I using 3 parts or more of the material.

Toner 4 of the present invention was obtained by adding and mixing surface-treated silica fine particles and zinc stearate to the treated particles in the same manner as in Example 1.

Surface observation using a scanning electron microscope and transmission electron microscope revealed that in this toner 4, not only the composite fine particles on the surface of the base particles but also the inorganic fine particles attached to the surface of the resin fine particles due to electrostatic force were removed from the resin fine particles. It was observed that the material was firmly adhered to the surface of the material.

<Example 5> Treated particles were obtained in the same manner as in Example 1 using 5 parts or more of base particles C. -11 95 parts composite fine particles 1.

0.0 parts of silica fine particles [Aerosil R-8+2J (manufactured by Nippon Aerosil Co., Ltd.) were added to 100 parts of the treated particles.
6 parts were added and mixed using a V-type mixer to obtain Toner 5 of the present invention.

<Comparative Example 1> Base particle A.
97 parts Resin fine particles 1- ・−・ −−−−・・−3
Treated particles were obtained in the same manner as in Example 1 using more than 100% of the materials, with fine resin particles fixed to the surface of the base particles.

Comparative toner 1 was obtained by adding and mixing surface-treated silica fine particles and zinc stearate to the treated particles in the same manner as in Example I.

Comparative Example 2 In Example 2, the base particles B and composite fine particles 1 were stirred and mixed using a Hennel mixer without using the Nara Hybridization System NH3-IJ.

Thereafter, surface-treated silica fine particles and zinc stearate were added and mixed in the same manner as in Example 1 to obtain Comparative Toner 2.

Comparative Example 3> Base particle a...
−・−・−・ 97 parts Composite fine particles 2・−・−・−−1−
-・------・-・ Treated particles were obtained in the same manner as in Example 1 using 3 parts or more of the material.

Comparative toner 3 was obtained by adding and mixing surface-treated silica fine particles and zinc stearate to the treated particles in the same manner as in Example I.

<Comparative Example 4> Base particle C・・・・・−・・・・・・・・−・−・−・
・・・・・・−・−−−−・・97 parts Resin fine particles l
・−・・−・・−・・−・−・・−・・−・・−・・
... Treated particles were obtained in the same manner as in Example 1 using 3 parts or more of the material, with fine resin particles fixed to the surface of the base particles.

Fine silica particles were added to and mixed with the treated particles in the same manner as in Example 5 to obtain Comparative Toner 4.

The structural characteristics of the toners obtained in the above Examples and Comparative Examples are summarized in Table 1 below.

<Test 1> For Toners 1 to 4 of the present invention and Comparative Toners 1 to 3, 2. 2. A two-component developer having a toner concentration of 6% by weight was prepared by mixing with a carrier coated with 2-trifluoroethyl methacrylate and having an average particle diameter of 80 μm.

Using these two-component developers, the system is equipped with a developing device for the two-component developer and a heat roller fixing device, the photoreceptor is replaced with a negatively charged organic photoreceptor, and the set temperature of the heat roller can be variably adjusted. Electrophotocopy machine rU-Bix 3042 modified to
J (-+-1-Riki) modified machine (line speed 2
40mm/sec) to form a fixed toner image while keeping the temperature of the backup roller lower than the set temperature of the heat roller and gradually changing the set temperature of the heat roller within the range of 100 to 240°C. I did a test.

After rubbing the near side end of the obtained fixed toner image in the image traveling direction with a rubbing tester applying a certain load, measuring the residual rate of the fixed toner image at the end with a microdensitometer, Low-temperature fixability was evaluated by determining the lowest temperature setting of the heat roller (minimum fixing temperature setting) when this residual rate was 80% or more.

Regarding Toner 5 of the present invention and Comparative Toner 4, unfixed toner images were formed using these as -component developers using an electrophotographic copying machine rNP-7550J (manufactured by Canon Inc.) for single-component developers.

This unfixed toner image was transferred to the rU-BiX 3042J
Using a heat roller fixing device of a modified machine (manufactured by Konica ■), a test was conducted to form a fixed toner image in the same manner as above, and the low temperature fixability was evaluated.

<Test 2> Regarding the two-component developer used in Test I, an electrophotographic copying machine rU-B in which the photoreceptor was replaced with a negatively charged organic photoreceptor was used.
Using a modified machine made by ix 3042J (manufactured by +-1-Riki), the set temperature of the heat roller was set to 160'C, and it was used in high-temperature, high-humidity environments (temperature 33 °C, relative humidity 80%) and low-temperature, low-humidity environments. A photo test was conducted 100,000 times each in an environment (temperature: 10° C., relative humidity: 20%), and the images were evaluated visually.

On the other hand, regarding the one-component developer used in Test 1, an electrophotographic image forming apparatus for one-component developer equipped with an amorphous silicon photoconductor, a non-contact developing device that applies an oscillating electric field to the development area, and a cleaning device with a cleaning blade. Using a prototype copier, we set the temperature of the heat roller to 160°C and conducted 100,000 live-action tests in both high-temperature, high-humidity environments and low-temperature, low-humidity environments in the same way as above, and visually inspected the images. It was evaluated.

The results of the above tests are shown in Table 2 below.

As is clear from Table 2, toners 1 to 5 of the present invention have good low-temperature fixing properties, and also show poor cleaning performance 100,000 times in both high-temperature environments and low-temperature, low-humidity environments. Good image quality was maintained with no image blur or fog.

Furthermore, there was no toner blocking in the developing section or cleaning section, and no toner filming on the photoreceptor or developing sleeve was observed.

On the other hand, Comparative Toners 1 and 4 use resin fine particles instead of composite fine particles treated with inorganic fine particles on the surface, so toner filming occurs on the photoreceptor and developing sleeve, especially at high temperatures. In high humidity environments, image blurring and poor cleaning occurred.

In addition, although Comparative Toner 2 uses composite fine particles, it is not fixed to the base particles, so it cannot be used in a high temperature and high humidity environment.
In both low-temperature and low-humidity environments, after 10,000 times, fogging increased and the image quality deteriorated.

In Comparative Toner 3, since the softening point of the binder resin combined with the base particles exceeds 120° C., the fixability of the initial image was poor, and the fixed toner was easily peeled off from the transfer paper. Also, a significant under-offset occurred.

〔Effect of the invention〕

As explained in detail above, according to the toner for electrostatic image development of the present invention, since the upper limit of the softening point of the binder resin of the base particles is set at 120°C, low-temperature fixability is good.
The composite fine particles can be sufficiently firmly fixed to the surface of the base particles by mechanical impact force.

Therefore, in the development process, toner filming is effectively prevented by the composite fine particles, and in the hot roller fixing process, the low-temperature fixing properties of the base particles are fully exhibited without being inhibited. As a result, it becomes possible to stably form a good image many times without causing deterioration in image quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a hybridizer that can be used for producing the electrostatic image developing toner of the present invention. 1...Powder input valve 3...Circulation circuit 5...Rotary plate 7...Stator 9...Powder discharge chute 2...Powder input chute 4...Casing 6... Blade 8... Jacket] 0... Powder discharge valve + 1 Figure

Claims (1)

[Scope of Claims] Composite fine particles whose surfaces are treated with inorganic fine particles are fixed to base particles containing a thermoplastic resin with a softening point of 120° C. or less as a binder resin by mechanical impact force. An electrostatic image developing toner characterized by: