JPH02308262A - Manufacture of toner - Google Patents

Abstract

PURPOSE:To obtain the toner with superior electrostatic rise characteristics by embedding a charge control agent in the particle surface of a precursor for the toner, manufactured by kneading, grinding, and classifying toner blended components other than the charge control agent, in the form of a primary particle. CONSTITUTION:Resin for fixation and a blending agent for toner other than the charge control agent are kneaded, and the kneaded body is ground and classified to manufacture the precursor for the toner. The toner precursor which is thus manufactured and contains no charge control agent and the charge control agent are mixed in the presence of a high shearing force and a high compressive force at temperature lower than the fusion point and softening point of resin for fixation. The charge control agent is ground into the form of primary particles, resin for fixation on the surface of the precursor is softened with frictional heat, etc., and the charge control agent is embedeed therein in the form of primary particles. Consequently, the obtained toner becomes fine and uniform in the dispersion of the charge control agent in the resin for fixation and extremely high electrostatic charging rise characteristics are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a toner, and more particularly, to a method for efficiently producing a toner with excellent chargeability.

(Prior Art) Dry toner used in electrophotography, that is, toner for two-component developers, is produced by rolling a mixture of toner ingredients such as a fixing resin, a coloring pigment, a charge control agent, and a release agent using a hot roll or the like. It is manufactured by kneading, pulverizing the kneaded material, and classifying it. However, in toners produced by such conventional methods, only a portion of the added charge control agent is used for controlling the charge of toner particles, resulting in a problem of low efficiency.

As a solution to this drawback, Japanese Unexamined Patent Publication No. 63-1311
No. 48 discloses that toner particles containing a binder resin and a colorant as main components are produced, and the toner particles and a charge control agent are mixed in a Henschel mixer, a ball mill, etc. to impart a charge to the surface of the toner particles. Depositing a control agent is described.

(Problems to be Solved by the Invention) The above-mentioned prior art is significant because it brings about effective use of the charge control agent and increase in the amount of charge on the toner particles by attaching the charge control agent to the surface of the toner particles. However, the toner particles and the charge control agent have not yet completely fused, and the band shape retention of the toner is not fully satisfactory.

Therefore, an object of the present invention is to provide a method for producing a toner for a developer which has excellent charging characteristics.

Another object of the present invention is that excellent charging properties can be obtained by using a small amount of charge control agent, and any desired chargeability, positive or negative, can be easily obtained by simply changing the type of charge control agent in the final mixing step. The present invention provides a method for producing toner.

(Means for Solving the Problems) According to the present invention, a fixing resin and a toner compound other than a charge control agent are kneaded, and the kneaded product is pulverized and classified to produce a toner precursor. mixing the precursor and a charge control agent powder at a temperature lower than the melting point or softening point of the fixing resin under high shear force and high compression force;
A method for producing a toner is provided, comprising the step of embedding a charge control agent in the form of primary particles on the surface of precursor particles.

(Function) The toner manufacturing method of the present invention includes the steps of granulating toner precursor particles containing all toner components other than the charge control agent, and applying the charge control agent to the surface of the precursor particles in the form of primary particles. The feature is that it consists of a step of embedding.

In the toner manufacturing process, a large amount of equipment and labor is required for kneading, pulverizing, and classifying, but in the present invention, the fixing resin and toner compounding agents other than the charge control agent are kneaded, and the kneaded product is The operations of pulverizing and classifying all toners can be performed on the same line, which saves equipment costs and improves productivity by increasing efficiency. Various toners with different chargeability can be manufactured while keeping the color and density constant.

The charge control agent-free toner precursor produced in this manner and the selected charge control agent are subjected to high shear and high compression at a temperature lower than the melting point or softening point of the fixing resin. Mixing is the second feature. That is, when a precursor and a charge control agent are mixed under high shear force and high compression force, the charge control agent is crushed into primary particles due to friction between the two, and the fixing resin on the surface of the precursor particle is pulverized. It is softened by frictional heat, etc., and the charge control agent is embedded therein in the form of primary particles. Therefore, in the toner according to the present invention, the charge control agent is finely and uniformly dispersed in the fixing resin, so as shown in the graph of FIG. can get. As a result, when toner is replenished, the toner and the magnetic carrier are sufficiently electrically coupled, and toner scattering is prevented.

In addition, in the toner according to the present invention, the charge control agent is completely fused to the surface of the toner particles, so compared to a toner in which the charge control agent is attached to the surface of the toner particles using a Henschel mixer, a ball mill, etc., the toner has the opposite polarity. Toner is low.

In this specification, melting point or softening point primarily means the melting point for a resin that has a melting point, and means the softening point for a resin that does not have a clear melting point.

In the present invention, during mixing under high shear force and high compression force as described above, the toner precursor particles are not substantially crushed and maintain their original particle size, while the charge control agent is crushed into primary particles. to cause embedding into the precursor particles.
Since the toner precursor particles are mainly composed of a fixing resin, they absorb shock and are inherently resistant to fragmentation, and the precursor particles have no shearing force on the secondary agglomerated particles of the charge control agent. It is recognized that this is related to the fact that the powder acts as a kind of grinding medium that transmits compressive force, and thereby the grinding and embedding of the charge control agent into the primary particles proceed simultaneously.

(Preferred Embodiment of the Invention) As the fixing resin used in the present invention, all resins conventionally used in electrophotographic toners can be used. Curable resins having melting points and softening points in the range of 60 to 200° C. are used. Suitable examples thereof include, but are not limited to, polystyrene, acrylic resins, styrene-acrylic copolymer resins, These include polyvinyl acetal resin, polyester resin, epoxy resin, phenol resin, petroleum resin, olefin resin, etc.

Examples of toner compounding agents other than charge control agents include release agents and various pigments. As the release agent, various animal and vegetable waxes, mineral waxes, polyethylene waxes, polypropylene waxes, etc. are used, and these are generally blended into the toner in an amount of 1 to 5% by weight.

As the pigment, in addition to coloring pigments, any of various pigments conventionally used in toners, such as magnetic pigments and conductive pigments, can be used. Suitable examples include, but are not limited to:

black pigment Channel black, furnace black, iron black.

Yellow pigments yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navels yellow, deftol yellow S1 banza yellow 10G, benzidine yellow G1 quinoline yellow lake, permanen yellow NGG, tartrazine lake .

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange, indanthrene brilliant orange RK, benzidine orange G1 indanthrene brilliant orange GK.

Red pigment Red pigment Red Garla, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Orange 4R, Lysole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D1 Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Purple pigment Manganese Purple, Fast Violet B1 Methyl Violet Lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indance blue BC
.

Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Final Yellow Green G0 White pigment titanium dioxide (titanium white), zinc white.

Extender pigments Palite powder, barium carbonate, clay, silica, white carbon, talc, aluminum white.

As the magnetic material pigment, for example, triiron tetroxide (Fe304
), iron sesquioxide (1'-Fe203), zinc iron oxide (ZnFe, 04), iron yttrium oxide (Y3Fe5
O12), cadmium oxide (Gd3Fe5012),
Iron copper oxide (CuFe204), iron oxide complex (PbFe+
zO+e), neodymium iron oxide (NdFeQs), barium iron oxide (BaFe+zO+*), magnesium iron oxide (MgFe20J, iron manganese oxide (MgFe20J)
, lanthanum iron oxide (LaFe0s), iron powder (Fe)
, cobalt powder (Go), nickel powder (Nl), etc., and any of these known fine powders of magnetic materials can be used in the present invention.

These pigments may have multiple functions.

For example, carbon black has the functions of a black pigment and a conductive pigment. Similarly, iron black (magnetite) has the functions of a black pigment and a magnetic pigment.

These pigments are preferably present in the toner in an amount of 5 to 15% by weight, particularly 7 to 12% by weight, depending on the intended use.

The manufacturing process of the toner precursor in the present invention is the same as the toner manufacturing process using a conventional pulverization method, except that no charge control agent is added, so the particle size of the precursor particles is not particularly described. It is preferable that the volume-based mean diameter measured by a counter is in the range of 5 to 30 μm, particularly 5 to 15 μm.

Any charge control agent conventionally used for toners can also be used as the charge control agent embedded in the toner precursor. Examples of the charge control agent include oil-soluble dyes such as nigrosine dye, oil black, and Subiron black, naphthenic acid, salicylic acid, octylic acid, higher fatty acids, and resin acids such as manganese, iron, cobalt, lead, zinc, and cerium. Examples include metal soaps which are metal salts such as calcium and nickel, metal-containing azo dyes, pyrimidine compounds, and metal chelates of alkylsalicylic acids. A typical example of a positive charge control agent is an oil-soluble dye, and a typical example of a negative charge control agent is a metal-containing complex dye.

These charge control agents are preferably used in an amount of 0.5 to 51% by weight, particularly 1 to 2% by weight, based on the toner, although it varies depending on the type thereof.

In the present invention, the precursor and the selected charge control agent are mixed at a temperature lower than the melting point or softening point of the fixing resin under high shear and high compression forces. One of the notable advantages of the present invention is that the temperature can generally be room temperature;
Of course, if the heat generated during mixing is too large, forced cooling may be performed using cooling water, cold air, brine, etc., or conversely, in order to shorten the mixing time, a heating medium such as hot water or steam may be passed through. Heating may be performed using means such as infrared heating or electric heating.

Mixing under high shear force and high compressive force means a mixing method in which high shear force and high compressive force simultaneously act on individual particles to be mixed, and ordinary high shear mixing means that high compressive force is also applied at the same time. They differ in how they work.

As such a mixing device, although not necessarily limited thereto, an Ong Mill manufactured by Hosokawa Micron Co., Ltd. can be used. In this Ong mill, there is a rotating casing that rotates at high speed, and inside the rotating casing there is an inner piece that rotates behind the rotating casing or is stopped. The mixture introduced into the casing is compressed against its inner wall by centrifugal force, and as it passes through the gap with the inner piece, it is strongly compressed and sheared.

The degree of centrifugal force is 50 to 1200G, especially 600 to 80G.
A range of 0G is appropriate; - The applied shearing force varies depending on the amount of the mixture to be prepared and the clearance between the inner piece and the rotating casing. - Generally speaking, it is not specified, but it corresponds to the centrifugal force mentioned above. A speed difference or a speed difference equivalent to about half of the centrifugal force is applied between the inner piece and the rotating casing, and the mixture layer that adheres to the casing due to the centrifugal force is 1/2 at the narrowest part with the inner piece. It is desirable that it be compressed to about /10 to 9/1O.

Although the processing time varies depending on the amount of the mixture to be charged and the amount of human power applied to the apparatus, generally a processing time of about 30 to 90 minutes is sufficient. The end point of the treatment can be determined by the fact that the charge control agent added to the precursor particles is embedded and the amount of free charge control agent is reduced.

The produced toner has a rounded shape even though the precursor is amorphous particles produced by a pulverization method, and if a sufficient processing time is given, it has a spherical or nearly spherical shape.

The treated toner is mixed with a fluidity improver made of hydrophobic silica such as Aerosil R972 (registered trademark) in an amount of 0.1 to 0.5% by weight per toner, and sprinkled in the mixer. It is filled with 1A and used as the final toner.

The toner according to the present invention can be mixed with a magnetic carrier such as ferrite or iron powder to develop an electrostatic latent image as a two-component developer or, if the toner contains a magnetic pigment, as a -component developer. be used advantageously.

(Effects of the Invention) According to the present invention, there is a step of manufacturing a toner precursor from toner ingredients other than a charge control agent by kneading, pulverizing, and classifying, and a step of manufacturing a toner precursor from toner ingredients other than a charge control agent, and applying a charge control agent to the particle surface of the precursor as a primary particle. By skillfully combining the process of embedding the toner with a shape, a toner with excellent charging rise characteristics was produced, and toner scattering could be prevented. In addition, the toner particle shape becomes almost spherical,
We were able to improve its fluidity. Furthermore, it has become possible to manufacture multiple types of toners with different chargeability through a common granulation line.

Furthermore, it has become possible to completely fuse the charge control agent to the surface of the toner particles.

(Example) [Example 1] Styrene acrylic resin 100 parts by weight (Mp
125°C) 10 parts by weight of carbon black (Printex 90: manufactured by Dexa Corporation) 2 parts by weight of low molecular weight polypropylene (Viscol 550P: manufactured by Sanyo Chemical Co., Ltd.) A mixture consisting of the above formulation was premixed using a Henschel mixer, and then a twin screw extruder was used. The mixture was melt-kneaded and allowed to cool. This kneaded product was roughly pulverized with a cutting mill, finely pulverized with an ultrasonic jet mill, and cut into particles with a particle size of 5 μm or less using an Alpine classifier.
A toner precursor having an average particle size of 11.0 μm in the μm range was obtained.

A mixture of 100 parts by weight of this toner precursor and 11 parts of a charge control agent (Bontron 5-34: manufactured by Orient Chemical Co., Ltd.)
00g was put into an Ong Mill (manufactured by Hosokawa Micron) and treated with a centrifugal force of 110G for 60 minutes to obtain the minus toner of the present invention.

[Example 2] 100 parts by weight of the toner precursor obtained in Example 1 and a charge control agent (Subiron Black TRH:
Immerse 100g of the lfilt mixture (manufactured by Hodogaya Chemical Industry Co., Ltd.) in an Ong Mill (manufactured by Hosokawa Micron Co., Ltd.), and
The mixture was treated with a centrifugal force of G for 60 minutes to obtain a minus toner of the present invention.

[Comparative Example 1] Styrene acrylic resin 100 parts by weight Carbon black 10 parts by weight (Printex 90; manufactured by Dexa Corporation) Charge control agent 1 part by weight (Bontron S-347 manufactured by Orient Chemical Co., Ltd.) Low molecular weight polypropylene 2 parts by weight (Viscol 550P) :
(manufactured by Sanyo Kasei Co., Ltd.) A mixture consisting of the above formulation was premixed using a Henschel mixer, then melt-kneaded using a twin-screw extruder and allowed to cool. This kneaded product was coarsely pulverized with a cutting mill, finely pulverized with an ultrasonic jet mill, and cut to particles with a particle size of 5 μm or less using an Alpine classifier. Obtained.

[Comparative Example 2] 100 parts by weight of the toner precursor obtained in Example 1 and a charge control agent (spiron black TRH:
1 part by weight (manufactured by Hodogaya Chemical Industry Co., Ltd.) was placed in a Henschel mixer, mixed and stirred to adhere the charge control agent to the surface of the toner precursor, thereby obtaining a toner.

(Evaluation) Developers were prepared by mixing 100 parts by weight of ferrite carrier (DFC-150: manufactured by Dowa Iron Powder Co., Ltd.) with 84 parts by weight of the toners of Example 1.2 and Comparative Example 1.2.

Charge Rise The charge amounts of the developers of Example 1 and Comparative Example 1 were measured using a blow-off charge amount measuring device.

The results are shown in Figure 1.

As shown in FIG. 1, Example 1 is superior to Comparative Example 1 in charging start-up.

f Charge amount distribution Regarding the developers of Example 2 and Comparative Example 2, the charge amount distribution was measured using a charge amount distribution measuring device (EST-1: manufactured by Hosokawa Micron Corporation).

The results of the f-coulometric distribution by particle size are shown in Table 1 and Figure 2. Further, the results of the charge amount distribution are shown in Table 2.

As shown in Table 1 and FIG. 2, in Example 2, the surface fusion of the toner precursor and charge control agent exhibits a small charge amount around 3.5 μm, which is the average particle size of Subiron Black TRH. I know what was done.

On the other hand, in Comparative Example 2, the amount of charge near 3.5 μm shows a large value, indicating that the surface fusion of the toner precursor and the charge control agent is incomplete, and there is a charge control agent that does not adhere to the toner precursor. I understand.

Further, as shown in Table 2, it can be seen that Example 2 contains less toner of opposite polarity than Comparative Example 2.

[Brief explanation of drawings]

FIG. 1 is a graph showing the rise characteristics of the blow-off charge amount in Example 1 and Comparative Example 1, and FIG.
3 is a graph showing the number distribution of particle diameters for the toner of Comparative Example 2.

Claims (1)

[Claims] (1) A step of kneading a fixing resin and a toner compounding agent other than a charge control agent, pulverizing the kneaded material, and classifying it to produce a toner precursor; a step of embedding the charge control agent in the form of primary particles on the surface of the precursor particles by mixing them under high shear force and high compression force at a temperature lower than the melting point or softening point of the fixing resin. A method for producing a toner, comprising: