JPH05107811A - Production of electrophotographic developer and electrophotographic developer - Google Patents

Abstract

PURPOSE:To provide a developer with at most one heating process and to improve dispersibility of various additives such as a magnetic powder, release agent, etc., by mixing a resin soln. and constitutional materials for the developer, drying the mixture and then pulverizing. CONSTITUTION:A resin soln. and constitutional materials such as a magnetic powder, release agent, etc., are mixed, then preferably heated and dried, and further pulverized. The amt. of the resin in the resin soln. is 15-65wt.%. The constitutional materials for the developer are added by 1-75wt.% to the resin amt. in the resin soln. and dried till the residual amt. of the solvent becomes <=200ppm. Thereby, heating process is required at most one time of the drying process, which decreases the process number and manpower, and decreases the production cost. Further, the amt. of the constitutional materials such as magnetic powder, release agent, etc., can be controlled to a desired value. Thereby, the obtd. developer shows good offset property, decrease in splashing of the toner, and small change in the density of picture images.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrophotographic developer and an electrophotographic developer.

[0002]

2. Description of the Related Art As electrophotographic developers for developing electrostatic latent images, various developers such as those using non-magnetic toner, those using magnetic toner, those using these and magnetic carrier are used. It has been known. The magnetic toner contains a resin, magnetic powder and various other internal additives, and the non-magnetic toner contains a resin, a colorant and various other internal additives.

A developer containing such a resin is conventionally manufactured by a dry method. In one example, the powder of each raw material composition is thoroughly mixed with a Henschel mixer,
Then, the mixture is kneaded with a hot melt kneader. Then cool down,
After coarse crushing with a hammer mill, fine crushing with a jet impact mill. Then, after removing the excess fine powder area with a wind classifier, after dry-mixing various external additives such as a fluidity improver with a Henschel mixer, the excess coarse powder area was removed with a wind classifier. , To obtain a developer having a predetermined particle size distribution.

However, when the dry method is used, mixing,
The dispersibility of various components during kneading is insufficient.
For this reason, a developer containing an excessive amount of magnetic powder, a release agent, or the like, or a developer containing an excessive amount of the releasing agent is produced. In this case, if the amount of the magnetic powder is too large, the density change of the image is large, and if the amount of the magnetic powder is too small, toner scattering occurs. Further, for example, if the amount of the release agent as the internal additive is too large, filming occurs on the photoreceptor, and if the amount of the release agent is too small, the offset is deteriorated. Such a situation is the same even when kneading conditions such as kneading time and temperature are changed.

Further, in order to manufacture the developer by the dry method, it is necessary to prepare a resin powder. For this reason, for example, a heating step for drying the resin after synthesizing the resin by solution polymerization is indispensable, and if the heating step when kneading with a hot melt kneader is included, a total of two heating steps are required. It needs to be done separately. Therefore, a large amount of labor is required to manufacture the developer by the dry method, and the manufacturing cost increases. Under such circumstances, it would be very beneficial if the developer could be manufactured by a maximum of one heating step.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to produce a developer by a maximum of one heating step, and to improve the dispersibility of various internal additives such as magnetic powder and release agent for electrophotography. It is to provide a method for producing a developer and a developer for electrophotography.

[0007]

These objects are achieved by the present invention described in (1) to (7) below. (1) A method for producing an electrophotographic developer, which comprises mixing a resin solution containing a resin and a developer constituent material, drying the mixture, and then pulverizing the mixture.

(2) The content of resin in the resin solution is 1
The method for producing a developer for electrophotography according to (1) above, which is 5 to 65% by weight.

(3) The method for producing an electrophotographic developer according to (1) or (2), wherein the developer-constituting material contains at least magnetic powder.

(4) The method for producing an electrophotographic developer according to any one of (1) to (3), wherein the resin solution is obtained by polymerizing a corresponding monomer by solution polymerization.

(5) The method for producing an electrophotographic developer according to any one of (1) to (4) above, wherein the drying is heating drying.

(6) 1 to 7 with respect to the resin in the resin solution
5% by weight of developer constituent materials are mixed, and the remaining solvent amount is 200
6. The method for producing an electrophotographic developer according to any one of the above (1) to (5), which is dried to a ppm or less.

(7) An electrophotographic developer produced by the method according to any one of (1) to (6) above.

[0014]

In the method for producing the electrophotographic developer of the present invention, for example, after the resin is synthesized by solution polymerization, the resin is used without being dried. Then, after mixing the resin solution and the developer constituting material such as magnetic powder and a release agent, it is preferably dried by heating and further pulverized. Therefore, the heating step only needs to be performed once at the maximum in the drying step, and as a result, the number of steps and labor can be reduced, and the manufacturing cost can be reduced.

Further, by manufacturing the developer by such a wet method, the dispersibility of various developer constituting materials at the time of mixing can be improved as compared with the conventional dry method. Therefore, the content of the constituent materials such as the magnetic powder and the release agent can be regulated to a desired fixed amount. As a result, the offset becomes good, the toner scattering is reduced, and the density change of the image can be reduced.

Conventionally, a dry method has been used in the production of a developer such as a toner, and it is unexpected that the wet method according to the present invention improves the dispersibility as compared with the conventional dry method. In the dry method, the kneading conditions such as the kneading time and the temperature by the hot melt kneader contribute to the dispersibility. Sex is difficult to obtain.

[0017]

[Specific Structure] The specific structure of the present invention will be described in detail below. In the method for producing a developer for electrophotography of the present invention, first, a resin solution containing a resin is prepared.

In this case, the resin used is not particularly limited, but a styrene copolymer resin is particularly preferable. The styrene-based copolymer resin is obtained by a copolymerization reaction between a styrene-based monomer and a copolymerizable vinyl-based monomer.

In this case, as the copolymerizable monomer,
Styrene and its derivatives, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-acrylate
Butyl, α-ethylhexyl acrylate, α-acrylic acid
-Hydroxyethyl, hydroxypropyl acrylate,
Acrylic ester or methacrylic acid such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, α-hydroxyethyl methacrylate, hydroxypropyl methacrylate. Examples thereof include acid esters, amides such as acrylamide, diacetone acrylamide, and N-methylol acrylamide, and vinyl esters, ethylene olefins, ethylenically unsaturated carboxylic acids, and the like.

Other resins include polyester resin, epoxy resin, silicone resin, fluorine resin, polyamide resin, acrylic resin, polyurethane resin, polyether resin, polyvinyl alcohol resin, polyethylene, ethylene-vinyl acetate copolymer, polypropylene and the like. Is mentioned.

Although only one kind of these resins may be used, two or more kinds may be mixed and used, if necessary. Further, these resins can be subjected to various known polymerization methods such as suspension polymerization method, emulsion polymerization method and bulk polymerization method in addition to the solution polymerization method, but the resin solution can be used as it is, and the polymerization method is very simple. The solution polymerization method is preferable because it is

The resin obtained by solution polymerization is heated and
It is used as a resin solution without being dried. At this time, a solvent may be further added if necessary.

The solvent used is not particularly limited as long as it can dissolve the resin, but benzene, triol,
Xylol, cyclohexane, methanol, ethanol, butanol, acetone, THF, MEK, MIB
A known organic solvent such as K, cyclohexanone, ethyl acetate or butyl acetate may be used.

The content of the resin in the resin solution is 15 to 65.
%, Especially 40 to 50% by weight is preferred. If the amount of the solvent with respect to the resin component is too large, it is uneconomical in manufacturing, and if it is too small, the viscosity is too high or undissolved substances are generated.
Then, by using the resin solution having such a resin amount, it is possible to satisfactorily perform mixing and dispersion with the developer constituting material of 1 to 75% by weight with respect to the resin.

When the resin is produced by the solution polymerization method, it is preferable to add a polymerization initiator, a catalyst, a chain transfer agent or a terminating agent to control the polymerization reaction.

Next, the resin solution and various internal additives as a developer constituent material are mixed to uniformly distribute the internal additives. The mixing / dispersing method in this case is not particularly limited,
Conventionally known mixing or kneading and dispersing methods may be used. Various conditions such as the mixing time may be appropriately determined according to the mixing and dispersion method.

The internal additive used is not particularly limited as long as it is used in various developers such as magnetic toner and non-magnetic toner.

For example, magnetic powder is one of the internal additives added to produce a magnetic toner. As the magnetic powder, metals such as iron, manganese, cobalt, nickel and chromium, alloys thereof, metal oxides such as chromium oxide, iron sesquioxide and ferrosoferric oxide, and general formulas MO / F can be used.
e ₂ O ₃ (M is Fe, Mn, Co, Ni, Mg, Zn,
Any of conventionally known magnetic materials such as ferrite represented by one or more metals selected from the group of monovalent or divalent metals such as Cd, Ba and Li can be used. If necessary, two or more of these may be used in combination.

The average particle size of the magnetic powder is 0.01 to
It is preferably 10 μm, particularly preferably 0.05 to 3 μm. In the case of a magnetic toner, the amount of magnetic powder relative to the resin and magnetic powder in the resin solution is preferably 10 to 70% by weight, more preferably 20 to 60% by weight. If the amount is too small, the magnetic force from the magnet inside the developing device is not sufficiently transmitted, and fog, toner scattering, etc. tend to deteriorate. On the other hand, if the amount is too large, the fixability of the toner deteriorates.

Waxes are an example of an internal additive for producing the developer of the present invention. Waxes
This is for the purpose of countermeasures against so-called offset development that occurs during fixing by a fixing roll, and for example, low molecular weight polyethylene, polypropylene, metal salts of fatty acids, silicone oil, etc. are used. A fluororesin is also effective as a release agent having such a function. The amount of these substances having a releasing action is 0.1 to 1 per 100 parts by weight of the toner.
It is preferable to contain 0 part by weight, more preferably 1 to 5 parts by weight.

Further, as a color adjusting agent and a resistance controlling agent, carbon black MA-100 [Mitsubishi Chemical Industries, Ltd.],
Inorganic or organic pigments such as Ketjen Black EC-DJ600 [Lion Akzo Co., Ltd.], 671 Miloli Blue [Dainichi Seika Kogyo Co., Ltd.] and conductive titanium oxide [Titanium Kogyo Co., Ltd.] can also be used. These are toner 1
It is preferable to contain 0 to 10 parts by weight, particularly 0 to 5 parts by weight, per 00 parts by weight.

In addition to the above, examples of the internal additive include a charge control agent, a fluidity improving agent described later, and a resistance adjusting agent.

In the case of non-magnetic toner, a colorant is contained. Examples of the colorant include black pigments such as carbon black, acetylene black, channel black and aniline black, yellow pigments such as diamond light GR and Vario reel yellow 1090, and permanent red E5.
B, red pigments such as rhodamine 2B, blue pigments such as copper phthalocyanine and cobalt blue, green pigments such as pigment green B, and orange pigments such as pyrazolone orange. Such a colorant is preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles.

Next, after mixing and dispersing as described above, the material is dried in order to remove the solvent, monomers and the like. The method for drying the material is not particularly limited, and a conventionally known drying device may be used. Drying is preferably carried out by heating, and various conditions such as heating temperature, heating time, atmosphere, etc., are used when the residual amount of solvent is 200 ppm or less, especially 50 pp.
The condition may be m or less, further 20 ppm or less. By reducing the amount of residual solvent, the temporal change in image density is reduced. The heating temperature is 50 to 300.
C., generally 120 to 200.degree. C. are preferred.

Next, pulverization is performed to obtain a developer. The manufacturing method after this pulverization is not particularly limited, but as one example, coarse pulverization is performed by a hammer mill and then fine pulverization is performed by a jet impact mill.

Then, the excess fine powder area is removed by an air classifier, the external additive and magnetic particles are optionally mixed by a Henschel mixer, and then the excess coarse powder area is removed by an air classifier. By removing, a developer having a predetermined particle size distribution is obtained. In this case, the external additive to be added is not particularly limited, and a fluidity improver or the like can be externally added.

Examples of these are metal oxides such as colloidal silica, titanium oxide, magnetic powder, zinc oxide and alumina, inorganic fine powders such as silicon carbide, calcium carbonate, barium carbonate and calcium silicate, PMMA, polyethylene, nylon, Polymer beads such as silicone resin, phenol resin, benzoguanamine resin and polyester, fluorine-containing organic fine powder such as polytetrafluoroethylene, polytetrafluoroethylene and polyvinylidene fluoride,
Fatty acid metal salts such as zinc stearate and magnesium stearate, carbon black, acetylene black,
Examples thereof include black pigments such as channel black and aniline black. It should be noted that these substances may be used alone or in combination of two or more if necessary.

As described above, these may be added internally into the developer particle composition and kneaded, or may be externally added and dry-mixed on the surface of the developer particles, thermally or thermally. It is possible to combine the forms as required, such as when mechanically fixed. Furthermore, each substance is a titanate type for surface hydrophobization treatment and surface dispersion improvement treatment,
An aluminum-based or silane-based coupling agent, silicone oil, and other organic or inorganic treatments can be applied. And these external additives are 0.01 to 5 μm.
The particle size is about m. The external addition amount is 0.1 to 5% by weight.
The degree.

Suitable ranges of various properties such as the average particle size and magnetic properties of the developer particles obtained by the method for producing a developer for electrophotography of the present invention as described above are different depending on the kind, and the following preferred examples are given. Explain.

In the case of magnetic toner, the average particle diameter of the magnetic toner particles is 3 to 25 μm, more preferably 3 to 20 μm.
And particularly preferably 4 to 12 μm. If it is too small, the fluidity of the developer is deteriorated, and caking of the developer and adhesion of the sleeve are likely to occur. If it is too large, the resolution is deteriorated and the fixing property tends to be poor. To measure the average particle diameter of the toner particles, the volume particle diameter of the measured value is calculated by the Coulter counter method, and the 50% average particle diameter thereof is taken as the average particle diameter. In the Coulter Counter method, Isoton II is used as the electrolyte.
(Manufactured by Coulter Electronics Co.), for example, Coulter counter TA- with an aperture diameter of 100 μm
Volume-based measurement is performed using II (manufactured by Coulter Electronics).

The particle size distribution is preferably such that 2d or more is about 5% or less, and d / 2 or less is about 5% or less, where d is the average particle size.

The coercive force Hc of the magnetic toner particles is, for example, 35 to 230 Oe at 5000 Oe, and particularly 40 to 140 Oe.
Is preferable, for example, the saturation magnetization σm at 5000 Oe
Is preferably 8 to 65 emu / g, and particularly preferably 15 to 40 emu / g.

In the case of non-magnetic toner, the average particle size of the non-magnetic toner particles is 3 to 25 μm, especially 4 to 12 μm.
In general, the particle size distribution is preferably such that 2d or more is 5% or less and d / 2 or less is 5% or less, where d is the average particle size.

[0044]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 Styrene prepared by a solution polymerization method using toluene
A resin solution containing 45% by weight of a butyl acrylate copolymer was obtained.

Then, the obtained resin solution was mixed with the following toner composition to form a slurry. Toner composition: (based on 55 parts by weight of resin in the resin solution) Magnetic powder BL-50 [manufactured by Titanium Industry Co., Ltd.] 40 parts by weight Heat-treated polypropylene VISCOL 550P [manufactured by Sanyo Chemical Industries] 3 parts by weight Charge control agent Eisenspiron Black TRH [manufactured by Hodogaya Chemical Co., Ltd.] 1 part by weight

These toner compositions were placed in a rotary disperser and dispersed at 3000 rpm for 60 minutes. Then, using a thin film evaporator for high viscosity liquid, 180 ° C, 50To
After the amount of residual solvent was reduced to 100 ppm or less at rr or less, coarse pulverization was performed with a hammer mill. After that, fine pulverization was performed with a jet impact mill.

Next, after removing the excess fine powder area with an air classifier, the following external additives were dry-mixed with a Henschel mixer, and then the excess coarse powder area was removed with an air classifier to obtain a predetermined amount. Toner A having a particle size distribution was obtained. The particle size distribution of Toner A when the external additive was not included was a volume average particle size of 11 μm, a particle size of 5 μm or less and 0.5% or less, and a particle size of 20 μm or more and 0.5% or less. Also 5000 Oe
The saturation magnetization .sigma.m at 34 .mu.m was 34 emu / g, and the coercive force Hc at 5000 Oe was 50 Oe.

External additive: (to 100 parts by weight of toner) Silica R-974 [manufactured by Nippon Aerosil Co., Ltd.] 0.5 parts by weight Nipseal SS60 [manufactured by Nihon Silica Co., Ltd.] 0.6 parts by weight

In addition to this, for comparison, in the method for producing the toner A, the resin solution is dried in a stainless steel vat at 180 ° C. for 48 hours to obtain a powdery resin, and the resin and the toner composition are Henschel. Mixed with a mixer. Next, in a hot melt kneader, 140 ° C, residence time: 0.
After kneading under the condition of 05 hr / Kg, it was cooled. Then, after the pulverizing step, the toner B for comparison is made in the same manner as the manufacturing method of toner A
Got Further, Comparative Toner C was obtained in the same manner as in the method for producing Toner B, except that the residence time in the hot melt kneader was increased to 0.2 hr / Kg.

When each of the obtained toners was cut with a microtome and the cross section was observed with a transmission electron microscope (TEM), the toner A had magnetic powder and the like uniformly distributed in the resin binder. Toners B and C were non-uniform as compared to Toner A.

Next, each toner was stored in a developing device in a reversal type toner image transfer type electrophotographic printer using an organic photoconductor as a photoconductor. In the developing device, the developing sleeve is arranged in parallel with the photoconductor drum with a minute gap therebetween, and has a built-in magnet roller that rotates at high speed.

Here, the developing sleeve is rotated at a low speed in the direction opposite to that of the photosensitive member, the magnet roller inside is fixed, and the developing bias is applied to the developing sleeve. Further, an agitator for preventing toner aggregation is provided in the developing device. Then, in this developing device, the developer is mixed and agitated by the rotation of the developing sleeve, and the toner and the carrier are supplied to the peripheral surface of the developing sleeve while being frictionally charged with each other. At this time, the developing conditions of the electrostatic latent image in the printer are as follows.

Sleeve roll: 65 rpm, diameter 20 mm Magnetic roll: fixed, 8 poles, surface magnetic flux 700 G Drum-sleeve gap: 0.25 mm Blade-sleeve gap: 0.23 mm Development bias: -350 V (DC) Surface potential: -400 V (OPC drum)

Printing was repeated under the above conditions and the following evaluations were performed.

1) Toner Scattering Continuous 1000-sheet printing was performed using an actual machine, and the scattering was visually confirmed.

2) Density variation range Density was measured using REFLECTOMETER MODEL TC-6D manufactured by Tokyo Denshoku Co., Ltd., Δ density of initial print density (A) and continuous print density (B) = AB The maximum value of was calculated. In this case, the initial sampling image is taken, and three images are sampled at a pitch of every 200 images, and continuous 1
000 prints were made. In addition, during continuous printing except during sampling, the black area becomes 5% of the total area 5%
Paper was passed in the print pattern. ◯: Δ concentration ≦ 0.15 Δ: 0.15 <Δ concentration ≦ 0.2 ×: 0.2 <Δ concentration

3) High-Temperature Offset The following fusing roll surface temperature was evaluated for stains during the roll cycle.

Table 1 shows the results of the toner scattering, the range of density change, and the offset.

[0060]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear. Also, the developer toner A is pulled by the carrier,
The resolution, fog, white stripes, sleeve adhesion, fixing rate, and line reproducibility were also good.

In addition to the above, non-magnetic toner and the like are prepared,
When the same evaluation as described above was performed, equivalent results were obtained.

[0063]

According to the method for producing an electrophotographic developer of the present invention, a resin drying step is not required, so that the labor is remarkably reduced and the production cost can be reduced. Moreover, at the time of mixing, the added developer constituent material can be uniformly distributed.

Claims (7)

[Claims] 1. A method for producing a developer for electrophotography, which comprises mixing a resin solution containing a resin and a developer constituent material, drying the mixture, and then pulverizing the mixture. 2. The content of the resin in the resin solution is 15 to
The method for producing an electrophotographic developer according to claim 1, wherein the amount is 65% by weight. 3. The method for producing an electrophotographic developer according to claim 1, wherein the developer-constituting material contains at least magnetic powder. 4. The method for producing an electrophotographic developer according to claim 1, wherein the resin solution is obtained by polymerizing a corresponding monomer by solution polymerization. 5. The method for producing an electrophotographic developer according to claim 1, wherein the drying is heating drying. 6. A developer constituent material is mixed in an amount of 1 to 75% by weight with respect to the resin in the resin solution, and the residual solvent amount is 200 ppm.
The method for producing an electrophotographic developer according to claim 1, wherein the drying is performed as described below. 7. An electrophotographic developer produced by the method according to claim 1.