JPH10307424A - Toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent electrification stability, cleaning property and fixing property for long-term use by controlling the surface covering rate of an aspherical particle with electrifying particles to specified % and causing melt sticking of electrifying particles on the rough surfaces of the aspherical particle. SOLUTION: The toner consists of aspherical particles 1 comprising a coloring agent and a binder resin and electrifying particles 2 fixed to the surface of each aspherical particle. The surface covering rate of the aspherical particle 1 with the electrifying particles 2 is 20 to 50%, and the electrifying particles are molten and stuck to each other on the rough surface of the aspherical particle 1. If the particle size of the electrifying particles is too large, it becomes difficult to firmly fix the particles and the particles easily drop from the surface of the aspherical particle 1. Therefore, the particle size is preferably <=0.5 μm. When the glass transition temp. and melt viscosity of the electrifying particles are too high, fixing property of the toner decreases, and if they are too low, aggregation of the toner easily occurs in an environment at high temp. Therefore, the glass transition temp. and the melt viscosity are preferably 50 to 80 deg.C and 10<4> to 10<6> Pa.sec at 140 deg.C, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner and a method for producing the same. More specifically, the present invention provides electrophotography,
The present invention relates to a toner used for developing an electrostatic latent image in electrostatic recording and the like, and a method for manufacturing the toner.

[0002]

2. Description of the Related Art In electrophotography, generally, a toner having a positive or negative charge is electrostatically attached to an electrostatic latent image formed on a photoconductive member, and then the toner image is transferred onto a transfer paper. And
It is obtained by forming an image by fixing. The toner used for image formation contains, as main components, particles having an average particle diameter of 5 to 20 μm, which are composed of a binder resin and a colorant, and is controlled to an appropriate charge amount by a frictional charging member such as a carrier or a charging blade.

Here, when the charge amount of the toner becomes larger than an appropriate value, the image density becomes smaller. On the other hand, when the charge amount of the toner is smaller than an appropriate value, it is known that toner scattering, background fogging, and the like occur, resulting in deterioration of image quality. In order to prevent these problems, a charge control agent is usually added to the toner. As the charge control agent added to the positively chargeable toner, a nigrosine dye, a pyridinium salt, an ammonium salt, a lake compound thereof, and the like have been conventionally used.

However, although these compounds are fine powders, they have a wide particle size distribution and do not have a fixed shape. Therefore, it is generally known that it is difficult to control the dispersion state of the charge control agent in the binder resin. Further, if the particle diameter of the charge control agent is too large, the charge control agent tends to separate during continuous copying, which causes contamination of a charging member such as a carrier. On the other hand, when it is too small, the action as a charge control agent is weakened. As a result, there is a drawback that charging rise of the replenished toner is delayed, causing problems such as image fogging and toner scattering. Further, the charge control agent has a disadvantage that the charge amount is difficult to stabilize because the ratio of the charge control agent exposed to the toner surface changes depending on the dispersion conditions at the time of toner production.

[0005] Apart from the above-mentioned method, there is also known a method of controlling charging of toner by fixing chargeable fine particles on the surface of toner. For example, a method in which chargeable particles are externally added to a toner surface and then fixed by applying a mechanical impact force using a powder surface modification device (Japanese Patent Application Laid-Open No. 63-244056).
Also, a method of externally adding chargeable particles and then fixing the toner and the chargeable fine particles under a high temperature condition equal to or higher than the softening temperature of the toner (Japanese Patent Application Laid-Open No. 62-226162) is known.

[0006]

However, according to the above-mentioned method, when the coverage of the toner surface with the chargeable particles is low, the chargeable particles are present in an individual state on the toner surface. There is a problem that it is easily detached or buried, so that the charge amount changes. If the chargeable fine particles are strongly fixed by mechanical energy in order to prevent this problem, the toner becomes spherical, so that cleaning with a blade becomes difficult.

In the method in which the entire surface of the toner is completely covered with the chargeable particles and the chargeable particles are fused together, the chargeable particles can be prevented from being separated or buried, but the heat fixability is also deteriorated. there were.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to provide a toner having excellent charging stability, cleaning properties and fixing properties when used for a long period of time. Invented the invention. Thus, according to the present invention, the chargeable particles are fixed to the surface of at least the non-spherical particles composed of the colorant and the binder resin, and the surface coverage of the non-spherical particles by the chargeable particles is 20 to 50%;
In addition, there is provided a toner characterized in that chargeable particles are fused to each other at a convex portion on the surface of a non-spherical particle.

Further, according to the present invention, non-spherical particles are put into a gas mixer, and the relationship between the temperature H (° C.) in the gas mixer and the glass transition temperature A (° C.) of the non-spherical particles is represented by the following general formula A- A method for producing a toner is provided, wherein the toner is produced by introducing chargeable particles into an airflow mixer while stirring under a condition satisfying 10 ≦ H ≦ A.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, the toner of the present invention has a configuration in which chargeable particles are fixed to the surface of non-spherical particles composed of at least a colorant and a binder resin. Here, examples of the colorant include inorganic colorants such as carbon black and magnetic powder, nitro, azo, stilbene azo, diphenylmethane, triphenylmethane, methine, thiazole, anthraquinone, and indamine series. , Azine, oxaazine, thiazine, sulfur dye, indigoid and phthalocyanine organic dyes and pigments.

Examples of the binder resin include polystyrene, styrene-acrylic copolymer, styrene-acrylonitrile copolymer, acrylic resin, styrene-maleic anhydride copolymer, and styrene-acryl-maleic anhydride copolymer. Coalescence, polyvinyl chloride, polyvinyl acetate, polyolefin resin, polyester resin, polyurethane resin, urethane modified polyester resin, epoxy resin and the like. These resins may be used alone or as a mixture. Further, the binder resin may have a polymer type such as a block copolymer, a graft polymer, and a crosslinked polymer.

As the non-spherical particles comprising the colorant and the binder resin, it is preferable to use amorphous particles having a particle size of 5 μm to 20 μm. When the particle size is smaller than 5 μm, the fluidity is lowered, which is not preferable. When the particle size is larger than 20 μm, the image quality is deteriorated, which is not preferable. Further, the mixing ratio of the coloring agent and the binder resin contained in the non-spherical particles,
Preferably, they are in the range of 5 to 50% by weight and 45 to 95% by weight, respectively. When the compounding ratio of the coloring agent is less than 5% by weight, the image density becomes low, which is not preferable.
If the amount is more than 50% by weight, the fixing property deteriorates, which is not preferable. The shape of the non-spherical particles is not particularly limited as long as it is not spherical, and it is sufficient that the non-spherical particles have at least a convex portion on the surface. Specific examples include a spheroid, a rectangular parallelepiped, a cube, a polyhedron, and a polyhedron having a crushed surface.

A fixing aid such as wax may be added to the non-spherical particles, if necessary. As a method for producing non-spherical particles, for example, a mixture comprising a colorant and a binder resin is melt-kneaded by a device capable of heating and mixing such as a biaxial kneader, and the obtained kneaded material is cooled and solidified, and the solidified material is cooled. Examples of the method include pulverization using a pulverizer such as a jet mill. The non-spherical particles obtained by this method are polyhedral non-spherical particles having a crushed surface.

Next, the chargeable particles fixed to the surface of the non-spherical particles are not particularly limited as long as they have chargeability and fusibility. For example, an optional charge control agent (CC) obtained by emulsion polymerization, non-emulsion polymerization, dispersion polymerization, suspension polymerization, etc.
Particles obtained by directly or finely pulverizing the resin particles containing A) can be used. In addition, CCA includes, for example,
Examples include metal complex salt dyes, dye / pigment intermediates, surfactants, and azine dyes. Further, particles obtained by emulsion polymerization or non-emulsion polymerization using a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, or amidinopropane hydrochloride can also be used. Here, the water-soluble polymerization initiator itself has a chargeability, and can easily control the chargeability, and the polymerization method has a particle diameter controllability, a glass transition temperature, and a melt viscosity. This is preferable because control can be easily performed.

When a water-soluble polymerization initiator is used, the above-mentioned chargeable particles have a desired charge amount without using a special monomer because the chargeable particles themselves have chargeability due to their own chargeability. Can be granted. In addition, if necessary,
During the production of the chargeable particles, the chargeability of the chargeable particles can be increased by copolymerizing with a polymerizable monomer having a polar group such as an amino group, an amide group, a carbonyl group, and a sulfonyl group. Examples of polymerizable monomers that can be used include, for example, styrene, p-methylstyrene, sodium styrenesulfonate, vinylbenzyl chloride, acrylic acid,
Examples include methyl acrylate, ethyl acrylate, butyl acrylate, dimethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and dimethylaminoethyl methacrylate. However, it is not limited to these.

If the particle size of the chargeable particles is too large, it is difficult to firmly fix them, and it is easy to separate from the surface of the non-spherical particles. Therefore, the particle size is preferably 0.5 μm or less. A more preferred particle size is 0.05 to 0.3 μm. If the glass transition temperature and the melt viscosity of the chargeable particles are too high, the fixability of the toner deteriorates, and if the glass transition temperature and the melt viscosity are too low, aggregation of the toner tends to occur in a high temperature environment. Therefore, the glass transition temperature is 5
The melt viscosity at 0 to 80 ° C and 140 ° C is 10 ⁴ to 10 ⁶
It is preferably within the range of Pa · sec.

Further, in the present invention, the non-spherical particles have a surface coverage of 5 to 50% and are coated with the chargeable particles.
Here, if the surface coverage is greater than 50%, the adhesiveness between the binder and the paper is undesirably deteriorated if the coverage of the chargeable particles is too high during heat fixing. On the other hand, if it is less than 5%, the charging rise time is undesirably long. The surface coverage is more preferably 20 to 50%.

Further, in the present invention, the chargeable particles are fixed to the surface of the convex portion of the non-spherical particles in a state of being fused to each other.
This is because the non-spherical toner has better blade cleaning properties than the spherical toner. However, the non-spherical toner receives a large stress on the surface of the convex portion, and when the chargeable particles on the surface of the toner convex portion are not fused to each other, burying or detachment is likely to occur. However, if the chargeable particles on the surface of the convex portion are fused to each other, burying and detachment are unlikely to occur even when stress is applied.

Next, a method for producing the toner of the present invention will be described. The toner of the present invention is manufactured by an airflow mixer. The airflow mixer used here preferably has at least a cylindrical outer wall whose temperature can be controlled and a stirring blade. Specifically, a Henschel mixer, a super mixer, a mechano mill and the like can be mentioned.

Next, the non-spherical particles are introduced into the gas mixer. Thereafter, the non-spherical particles are agitated in a gas-flow mixer. The relationship between the temperature H (° C.) in the gas-flow mixer and the glass transition temperature A (° C.) of the non-spherical particles is represented by the following general formula: A-10 ≦ The condition satisfying H ≦ A is maintained. Here, it is not preferable that the temperature in the airflow mixer is higher than the glass transition temperature of the non-spherical particles because the non-spherical particles fuse together. On the other hand, if the temperature is lower than the glass transition temperature of the non-spherical particles by 10 ° C., the fixing power of the chargeable particles becomes weak, which is not preferable.

Next, chargeable particles are introduced into the airflow mixer. Here, the collision energy between the non-spherical particles and the stirring blade or the outer wall rotating in the airflow mixer acts as the fixing energy between the non-spherical particles and the chargeable particles. The point of action of this collision energy is concentrated on the projections of the non-spherical particles. Therefore, by introducing the chargeable particles into the airflow mixer under stirring, the chargeable particles are selectively dispersed on the convex portions of the surface of the non-spherical particles before being uniformly dispersed on the surface of the non-spherical particles. It is fixed to the density (see FIG.
Represents non-spherical particles, and 2 represents chargeable particles). Furthermore,
By maintaining the stirring, the collision energy acts as an energy for fusing the charged particles fixed to the surface of the non-spherical particles to each other (see FIG. 2 (b); Shows the charged particles deposited).

When the above-mentioned chargeable particles are fixed, other particles containing a preservability-imparting agent or the like may be fixed simultaneously if necessary. The introduction of the other particles may be performed continuously with the introduction of the chargeable particles, or may be performed intermittently. The toner of the present invention can be used in combination with a known external additive such as silica, titanium oxide, or alumina fine particles for the purpose of imparting fluidity or abrasiveness. In addition to being usable as a one-component developer, it can also be used as a two-component magnetic brush developer by mixing with a magnetic powder carrier.

[0023]

Next, the present invention will be described in more detail by way of examples. All parts in Examples are parts by weight. Example 1 Styrene-acrylic copolymer resin [Glass transition point (Tg) 55 ° C, number average molecular weight (Mn) = 3 × 10 ³ , weight average molecular weight (Mw) = 2 × 10 ⁵ ] 100 parts carbon black ( MA-100 manufactured by Mitsubishi Kasei Co., Ltd. 6 parts Polypropylene wax (Viscol 550P manufactured by Sanyo Chemical Co., Ltd.) 2 parts A mixture of the above materials was stirred with a super mixer for 2 minutes.
Melt-kneaded with a twin-screw kneader, and then cooled and solidified, and then pulverized with a jet mill pulverizer to obtain a weight-average particle diameter of 10.
Polyhedral colored non-spherical particles having a particle diameter of 7 μm and a number average particle diameter of 7.3 μm were obtained.

Next, using a Henschel mixer having a cylindrical outer wall whose temperature can be controlled and a stirring blade, the non-spherical shape is controlled with the tip peripheral speed of the stirring blade controlled at 20 m / sec and the temperature inside the Henschel mixer at 50 ° C. While stirring 100 parts of the particles, positively chargeable particles (Tg of 80 ° C., particle diameter of 0 ° C.) comprising methyl methacrylate (MMA) -butyl methacrylate (BMA) copolymer resin particles obtained by emulsion-free polymerization using amidinopropane hydrochloride. .15 μm, 140
Melt viscosity at 10 ° C. 10 ⁶ Pa · sec or more)
It was introduced into an airflow mixer and fixed for 10 minutes.

To 100 parts of this powder, 0.3 part of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was externally added to prepare a toner exhibiting positive chargeability. When this toner was observed with a scanning electron microscope (SEM), it was found that 50% of the toner surface was covered with the chargeable particles, and the chargeable particles were fixed to the convex surface of the toner in a fused state with each other.

Example 2 A toner was prepared in the same manner as in Example 1 except that the control temperature in the Henschel mixer was changed to 55 ° C. Observation of this toner by SEM revealed that 50% of the toner surface was covered with the chargeable particles, and that the chargeable particles were fixed to the convex surface of the toner in a fused state.

Example 3 Positively chargeable particles (Tg 80 ° C., particle size 0.40 μm) made of MMA-BMA copolymer resin particles obtained by emulsion-free polymerization using amidinopropane hydrochloride as the chargeable particles
m, and a melt viscosity at 140 ° C. of 10 ⁶ Pa · sec or more), except that a toner was produced in the same manner as in Example 1. When this toner was observed with an SEM, the toner surface 2
0% was covered with the chargeable particles, and the chargeable particles were fixed to the surface of the convex portion of the toner in a fused state.

Example 4 Positively chargeable particles (Tg 65 ° C., particle size 0.15 μm) composed of MMA-BMA copolymer resin particles obtained by emulsion-free polymerization using amidinopropane hydrochloride as chargeable particles
m, melt viscosity at 140 ° C. 3 × 10 ⁵ Pa · se
A toner was prepared in the same manner as in Example 1, except that c) was used. Observation of this toner by SEM shows that 5
0% was covered with the chargeable particles, and the chargeable particles were fixed to the surface of the convex portion of the toner in a fused state.

Comparative Example 1 Using the Henschel mixer having a cylindrical outer wall capable of controlling the temperature and a stirring blade, the non-spherical particles and the charging particles used in Example 1 were set at a tip peripheral speed of 20 m / sec. After mixing for 20 minutes while controlling the temperature in the Henschel mixer to 30 ° C. or less, the temperature in the Henschel mixer was reduced to 50 ° C.
C. and fixed for 10 minutes.

To 100 parts of the obtained particles, 0.3 part of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was externally added to obtain a toner having positive chargeability. When this toner was observed with an SEM, the chargeable particles were sparsely fixed on the toner surface.

Comparative Example 2 Comparative Example 1 was conducted except that the amount of the chargeable particles was changed to 7 parts.
A toner was prepared in the same manner as described above. When this toner was observed with an SEM, it was found that the entire surface of the toner was fixed with the charged particles.

Comparative Example 3 The non-spherical particles and the chargeable particles used in Example 1 were mixed with a cylindrical Henschel mixer having a temperature-controllable outer wall and stirring blades at a tip peripheral speed of 20 m / sec. ,
After mixing for 20 minutes while controlling the temperature in the Henschel mixer to 30 ° C. or less, the temperature in the Henschel mixer was reduced to 6%.
The temperature was raised to 0 ° C. and a fixing treatment was performed for 10 minutes.

To 100 parts of the obtained particles, 0.3 parts of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was externally added to obtain a toner having positive chargeability. When this toner was observed with an SEM, the shape of the toner was almost spherical.

Experimental Example Each of the toners of Examples 1 to 4 and Comparative Examples 1 to 3 was mixed with 100 parts of a ferrite carrier coated with 4 parts of a fluororesin to prepare a developer. Using these developers, a continuous copying test of 10,000 copies was performed with a copying machine (SF-8300 manufactured by Sharp Corporation). The results shown in Table 1 were obtained.

[0035]

[Table 1]

As is clear from the results shown in Table 1, the toner according to the present invention is excellent in charge stability, fixing property and cleaning property, and has a high image density even in continuous copying and gives an image without fog.

[0037]

The toner according to the present invention has a non-spherical shape.
Since the surface coverage of the chargeable resin particles is low and the chargeable particles are less buried and detached, the chargeability is excellent, and the chargeability is excellent, and excellent charge stability can be maintained even when used for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic view of a toner of the present invention.

[Explanation of symbols]

 1 Non-spherical particles 2 Chargeable particles 3 Charged particles fused

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Nishigaki 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation

Claims (5)

[Claims] Claims: 1. A non-spherical particle comprising at least a colorant and a binder resin, wherein a chargeable particle is fixed on a surface of the non-spherical particle,
The surface coverage of the non-spherical particles by the chargeable particles is 5 to 50%.
Wherein the chargeable particles are fused to each other at the projections on the surface of the non-spherical particles. 2. The toner according to claim 1, wherein the chargeable particles are resin particles having a particle size of 0.5 μm or less. 3. The toner according to claim 1, wherein the chargeable particles have a glass transition temperature of 50 to 80 ° C. and a melt viscosity at 140 ° C. in a range of 10 ⁴ to 10 ⁶ Pa · sec. 4. The toner according to claim 1, wherein the chargeable particles are resin particles obtained by non-emulsion polymerization or emulsion polymerization using a water-soluble polymerization initiator. 5. A non-spherical particle is put into an airflow mixer, the temperature H (° C.) in the airflow mixer and the glass transition temperature A of the nonspherical particle.
The toner according to any one of claims 1 to 5, wherein the chargeable particles are introduced into an airflow mixer while stirring under a condition that the relationship of (° C) satisfies the following general formula: A-10 ≦ H ≦ A. And a method for producing a toner.