JPH08129270A - Production of toner composition - Google Patents

Abstract

PURPOSE: To produce a toner excellent in fixability and image characteristics such as image density and fog by specifying the temp. of the 1st kneading part of a continuous kneader used in a kneading process. CONSTITUTION: When at least a resin and a colorant are blended, mixed, kneaded with a continuous kneader, pulverized and classified to produce a toner compsn., the set temp. Ta( deg.C) of the barrel of the 1st kneading part of the continuous kneader and the flow softening temp. Tm( deg.C) of the resin are regulated so as to satisfy the relation of Ta<=Tm+20. A known resin fit for a toner may be used as the resin and styrene resin, polyester resin or epoxy resin is especially preferably used. The colorant content is made low if it is enough to color the toner so that a visible image can be formed by development.

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 a toner composition used in electrophotography, electrostatic recording and the like.

[0002]

2. Description of the Related Art A developer used in an electronic copying machine or the like is once attached to an image carrier such as a photoconductor on which an electrostatic charge image is formed in the developing process, and then is transferred to the photoconductor in the transferring process. After being transferred from the sheet to the transfer sheet, it is fixed on the copy sheet surface in the fixing step. At that time, as a developer for developing the electrostatic image formed on the latent image holding surface, a two-component developer consisting of a carrier and a toner and a one-component developer not requiring a carrier (magnetic toner, non-magnetic Magnetic toner) is known. Toners contained in the developer include positively charged toners and negatively charged toners. Conventionally, as the toners imparting chargeability to the positively charged toners, nigrosine dyes, quaternary ammonium salts, etc., As a material for imparting chargeability to a negatively chargeable toner, a charge control agent such as a metal-containing dye or a coating agent for imparting a predetermined chargeability to a carrier has been known.

FIG. 1 shows an example of a toner manufacturing flow that is normally performed. First, a predetermined amount of materials such as a resin and a colorant are mixed and mixed, melt-kneaded with a kneader, cooled, pulverized, and classified. Further, the classified toner and the external additive are stirred and mixed, and then a coarse product is sieved and filled in a container. Conventionally, there have been various proposals regarding kneading techniques for the purpose of improving toner performance. For example, JP-A-6-118713 proposes to regulate the cylinder temperature of an extruder to reduce the release agent released from the toner, and JP-A-6-95.
Japanese Patent Laid-Open No. 433/433 proposes that the fixing property and the developability are improved by defining the (paddle total length) / D (screw diameter) of the extruder and the position of the kneading portion.
No. 13415 proposes to control the toner charging start-up speed by the cylinder temperature or the number of rotations of the main shaft in the kneading step, and in JP-A-6-194878, the cylinder set temperature of the extruder is the minimum temperature of the kneaded product discharged. There is a proposal to improve the toner fixing strength by setting the temperature within ± 20 ° C of T ° C.

However, the conventional kneading technique has a problem that sufficient toner performance cannot be obtained. In particular, in recent years, (a) the flow softening temperature of the binder resin used with the speed increase of the copying machine and the shortening of the first copy time is designed to be lower than the fixing surface. Is more likely to cause non-uniformity of the toner composition, and (b) the uniformity of the toner composition becomes a problem because the particle size of the toner is reduced as the image quality of the copy becomes higher. A good toner manufacturing technique was desired.

[0005]

Therefore, the first aspect of the present invention
It is an object of the present invention to provide a method for producing a toner having excellent toner fixing performance and image characteristics such as image density and fog. The second object is to provide a method for producing a toner having a uniform composition and good dispersion of additives in the toner. A third object is to provide a method for producing a toner that has little environmental dependence on temperature, humidity and the like and has excellent storage stability even at high temperatures. A fourth object is to provide a method for producing a toner which has stable image characteristics, image quality, charging characteristics and the like even when continuous copying is performed, and which has excellent durability.

[0006]

As a result of various studies by the present inventors, it was found that toner performance can be improved by specifying the temperature of the first kneading part of the continuous extruder used in the kneading step. The present invention has been reached. That is, the gist of the present invention is to provide a method for producing a toner composition in which at least a resin and a colorant are blended and mixed, then kneaded in a continuous extruder, and then pulverized and classified. The relationship between the barrel set temperature Ta (° C.) of the part and the flow softening temperature Tm (° C.) of the resin is Ta ≦ Tm + 20.

Hereinafter, the present invention will be described in detail. As the resin used in the present invention, known resins suitable for toner can be used. For example, polystyrene, polychlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer. Polymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene- Phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer and styrene-phenyl methacrylate) Copolymer, etc.), styrene-α- Styrene-based resins such as methyl chloroacrylate copolymer and styrene-acrylonitrile-acrylic ester copolymer (styrene or a styrene-substituted homopolymer or copolymer),
Vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin (including saturated and unsaturated), polyethylene resin, polypropylene resin,
There are ionomer resins, polyurethane resins, silicone resins, ketone resins, ethylene-ethyl acrylate copolymers, xylene resins, polyvinyl butyral resins, and polycarbonate resins, but as a particularly preferable resin for use in the present invention, a styrene resin, Examples thereof include polyester resins and epoxy resins. Further, the above resins are not limited to be used alone, but may be used in combination of two or more kinds.

The flow softening temperature (T
m) is preferably 80 ° C to 145 ° C, particularly preferably 80 to 140 ° C. If the temperature is lower than 80 ° C, the fixing temperature to the paper is low and good, but hot offset is likely to occur, and the toner is liable to be crushed inside the developing tank, so that the toner is fixed on the carrier surface or the doctor blade. However, there is a problem in that the charging characteristics are deteriorated and the charging characteristics are deteriorated, and the durability performance of the developer is deteriorated. Also,
When the temperature is higher than 145 ° C., there are problems that the fixing temperature on the fixing paper is high and the pulverizability of the toner is poor.

The glass transition temperature of the resin is preferably about 45.degree. C. or higher. If the temperature is lower than 45.degree. C., when the toner is left at a high temperature of 40.degree. There is a problem in use such that toner agglomerates are likely to be generated in the external addition step and that they are easily attached to the screen, the side wall and the like of the sieving device. The resin may be produced by known solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like, and the polymerization method of the low molecular weight polymer and the high molecular weight polymer may be different as necessary. Further, from the viewpoint of the odor of the toner, the total amount of the light-boiling components such as the amount of residual monomers and the amount of residual solvent in the resin is 1,000 ppm or less, preferably 500.
ppm or less is preferable.

Each test method for the resin used in the present specification will be described below. [Flow softening temperature (Tm), flow end temperature (Te)]
Flow tester (CFT-50 manufactured by Shimadzu Corporation)
In 0), 1 g of the sample was used as a nozzle 1 mm × 10 mm die, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a heating rate of 3
The measurement is performed under conditions of ° C / min, the temperature at the midpoint of the distance from the start to the end of the flow is the softening temperature Tm, and the temperature at which the flow ends is the end temperature Te.

[Glass transition temperature (Tg)] A transition (inflection) start part of a curve measured by a differential thermal analyzer (DTA-40 manufactured by Shimadzu Corp.) under the condition of a heating rate of 10 ° C./min. A tangent line is drawn to the glass transition temperature. As the colorant used in the present invention, known pigments and dyes may be used. For example, carbon black, titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine blue, navy blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane type Coloring agents such as dyes, anthraquinone dyes, monoazo and diazo dyes and pigments can be used alone or in admixture of two or more.

The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development. For example, 1 to 20 parts by weight, preferably 100 parts by weight of the resin is preferable. 3 to 15 parts by weight can be contained. Further, a known positively or negatively chargeable charge control agent may be used alone or in combination in the toner, and the amount thereof may be selected according to the desired charge amount ratio, for example, 100 parts by weight of the resin. On the other hand, it is about 0.05 to 10 parts by weight. Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds, imidazole compounds, polyamine resins and the like. As the negative charge control agent, Cr, Co,
There are metal-containing azo dyes such as Al and Fe, salicylic acid metal compounds, alkylsalicylic acid metal compounds, and carlix arene compounds.

Further, if necessary, other internal additives may be used alone or in combination as an auxiliary agent, and examples thereof include low molecular weight olefin polymers of known release agents, fillers and the like. First, an example of the toner production flow of the present invention will be described with reference to FIG. 1, but the present invention is not limited to the following description as long as the gist thereof is not exceeded. As a toner internal additive, at least a predetermined amount of a resin and a colorant are weighed, mixed, and mixed. Examples of the mixing device include a double cone mixer, a V type mixer, a drum type mixer, a super mixer, a Henschel mixer, and a Nauta mixer.

Next, in the kneading step, a continuous kneading device is used because of its superiority such as continuous production. In recent years, a single-screw or twin-screw extruder has been the mainstream, and a twin-screw extruder is available from Sigma Publishing "Twin Screw Extrusion-Technology and Theory-" (Published March 1, 1993, Author James)
L. White), etc., for example, KTK type twin-screw extruder manufactured by Kobe Steel, TEM type twin-screw extruder manufactured by Toshiba Machine Co., Ltd., twin-screw extruder manufactured by KCK, Ikegai Tekkosha A PCM type twin-screw extruder, a Kuriyama Seisakusho's twin-screw extruder, and Bus Co's co-kneader are preferable. After the kneading, the toner is rolled by two rolls or the like, and is subjected to a cooling step of cooling by air cooling, water cooling, or the like.

Next, in the pulverizing step, coarse pulverization is performed by a crusher, hammer mill, feather mill, etc., and fine pulverization is performed by a jet mill, a high speed rotor rotary type mill, etc., and the toner particles are pulverized stepwise. After crushing, inertia classification type elbow jet, centrifugal force classification type microplex, D
The toner is classified with an S separator or the like, and the average particle size is 3 to 1
5 μm toner is obtained. The toner coarse powder generated in the classification step may be returned to the crushing step, and the fine powder generated may be returned to the blending step of the toner raw materials for reuse.

Further, when the toner is externally added, a classified toner and various known external additives are mixed in a predetermined amount, and agitated by a high speed agitator such as a Henschel mixer or a super mixer which gives a shearing force to the powder.・ It is good to mix. At this time, since heat is generated inside the external additive machine and aggregates are easily generated, it is preferable to adjust the temperature by means such as cooling the periphery of the container part of the external additive machine with water. The material temperature is preferably not higher than the control temperature, which is about 10 ° C. lower than the glass transition temperature of the resin.

As the external additive, various known inorganic or organic external additives can be used. In particular, in order to improve the fluidity of the toner and suppress the cohesiveness, titania, silica, alumina, zinc oxide, and oxidation are used. Inorganic fine powder such as magnesium is suitable. The amount of the external additive mixed varies depending on the external additive used, the average particle size of the toner particles, the particle size distribution, etc.
The desired fluidity of the toner is obtained, and for example, 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight is suitable for 100 parts by weight of the toner particles. If the mixing amount is less than 0.05 part by weight, there is no fluidity improving effect and the storage stability at high temperature is poor, and if the mixing amount is more than 10 parts by weight, filming occurs on the photoconductor due to a part of the external additive liberated. Undesirably, or it accumulates inside the developing tank and causes problems such as deterioration of the charging function of the developer.

From the viewpoint of stability in a high humidity environment, the external additive is preferably an inorganic fine powder which has been subjected to a hydrophobic treatment with a treatment agent such as a known silane coupling agent, and is further preferably charged. When considering the property, dimethyldichlorosilane, monooctyltrichlorosilane, hexamethyldisilazane, silicone oil, etc. are used as the treatment agent that imparts negative chargeability, and aminosilane, etc. is used as the treatment agent that imparts positive chargeability. do it.

In addition to the above, magnetite, farite, conductive titanium, antimony oxide, tin oxide, cerium oxide, hydrotalcites, etc., other than those for improving fluidity, are used as toner external additives for the purpose of resistance adjustment, abrasives, etc. An appropriate amount of fine powder such as a compound, acrylic beads, silicone beads, and polyethylene beads may be mixed, and the mixing amount may be toner 1
0.005 to 10 parts by weight is preferable with respect to 00 parts by weight. The obtained toner is a one-component developer that does not use a carrier (a magnetic one-component toner containing a magnetic substance such as magnetite or a non-magnetic one-component toner containing no magnetic substance), or iron powder, ferrite, or magnetite. , A two-component developer mixed with a magnetic carrier such as a magnetic resin carrier.

FIG. 2 shows an example of the continuous extruder used in the present invention, and the kneading step will be described in more detail. The cylinder 4 is divided into 9 blocks of barrels 5 to 13, and 8 blocks of the barrels 6 to 13 and the die 15 have a heating means such as an electric heater and a cooling means for cooling with a refrigerant such as water inside or outside. The temperature is controlled by the temperature control panel. Further, the barrel 5 has the raw material supply port 1 on the upper part, and the vent ports 2, 3 on the upper parts of the barrel 10 and the barrel 12.
Have respectively. Inside the extruder, there is provided a screw in which two three-row type shafts are engaged with each other and rotate in the same direction at a high speed of about 100 to 500 rpm. The screw configuration can be appropriately selected. For example, the screw configuration as shown in FIG. 4 may be configured with the feed section screws 30, 31, 32 and the kneading section screws 33, 34. It is better to arrange at least one place. The first kneading portion in the present invention means the first portion where the toner raw material is substantially kneaded, and the first kneading portion (the portion of the screw 33).
The set temperature Ta (° C.) of the barrel 9 is less than or equal to the flow softening temperature Tm (° C.) + 20 ° C. of the resin used, and is preferably Tm or less. Ta is the glass transition temperature Tg of the resin.
(° C.) or higher, and particularly preferably Tg + 5 ° C. or higher. When Ta is lower than Tg, it is difficult to obtain a sufficient molten state due to self-heating, and in some cases, a part of the toner component is discharged as dust from the vent port 2 to the outside of the system, so that the composition in the toner is sufficiently dispersed. Is not obtained, and fogging, toner scattering, etc. are liable to occur, which is not preferable.
When a is higher than Tm + 20 ° C., a sufficient load is less likely to be applied at the first kneading portion, sufficient uniformity of the toner composition cannot be obtained, and an image with poor gradation is likely to result in deterioration of toner scattering, which is preferable. Absent.

The toner raw material is fed from the raw material hopper 20 into the raw material supply port 1 by the screw feeder 21 and is supplied to the feeding section screw 30. Thereupon, the raw material is gradually preheated, and a strong load is applied to the first kneading section screw 33, so that the raw material itself disperses due to self-heating, and the solid changes from a molten state. The raw material is in a sufficiently molten state when it passes through the barrel 10, and the second kneading section screw 34 further improves the miscibility of the kneaded product. Finally, the kneaded product is pushed out of the system through the outlet 16. The temperature (Tk) of the discharged kneaded material is preferably equal to or higher than the flow end temperature (Te) of the resin used, and preferably Tk ≧ Te + 10.
When Tk is lower than Te, the additive is not sufficiently dispersed in the resin, the composition becomes non-uniform, and fogging and toner scattering are likely to be unfavorable. Although the vent 2 is open to the atmosphere, the vent 3 provided in the middle of kneading is sucked by a vacuum pump 24 to remove gas such as air in the kneaded product to improve miscibility and improve dispersion. In addition, residual monomer components, residual solvent components, etc. in the toner can be removed, and impurities can be removed and odor can be reduced. Inside the screw of the extruder, for cooling the inside, a refrigerant supply device 36 passes through a refrigerant supply path 35 (41, 42),
For example, water or brine may be supplied.

When the inner diameter of the cylinder is D (mm) and the length L (mm) from the center of the material supply port to the tip of the cylinder is L / D, 20 or more is preferable, and 25 or more is preferable. When L / D is less than 20, it is difficult to sufficiently knead the toner, and it is easy to cause fog and toner scattering due to uneven toner composition, which is not preferable. Furthermore,
When the length from the center of the material supply port to the starting point of the first kneading portion is L ₁ (mm), the first kneading portion screw is provided at a position where L ₁ / D is 5 or more. It is good, and preferably it is provided at a position corresponding to L ₁ / D of 10 or more. If the starting point of the first kneading portion is provided at a position where L ₁ / D is less than 5, the raw material cannot be preheated sufficiently, the resin is suddenly loaded, the composition is hardly homogenized, and fog and toner scattering are deteriorated. Is likely to be caused, which is not preferable.

[0023]

By using the method for producing a toner composition of the present invention, the composition in the toner can be made uniform even if a resin having a low flow softening temperature is used, and the toner fixing performance is good and continuous. The image / image quality characteristics are stable even at the time of use, the durability is excellent, the dependence on the use environment is small, and the toner performance is excellent in storage stability.

[0024]

EXAMPLES In the following examples, "parts" simply means "parts by weight".

[0025]

Table 1 Styrene / n-butyl acrylate copolymer resin 100 parts (Tm = 130 ° C., Te = 140 ° C., Tg = 60 ° C.) Colorant Carbon black MA-100S (Mitsubishi Kasei Co., Ltd.) 6 Part-Charge control agent Bontron P-51 (Orient Chemical Industry Co., Ltd.) 2 parts-Low molecular weight wax VISCOL 550P (Sanyo Chemical Co., Ltd.) 2 parts

Were mixed in a V-type mixer and kneaded in a continuous extruder (PCM type manufactured by Ikegai Co., Ltd.) shown in FIG. 2, cooled and solidified, coarsely crushed, jet mill crushed, and air-sized to average particles. A black toner having a diameter of 9 μm was obtained. To 100 parts by weight of this black toner, silica powder (R97 of Nippon Aerosil Co., Ltd.)
2) 0.35 parts and magnetite fine powder (Toda Industry Co., Ltd.)
0.2 part of EPT1000) was externally added by a Henschel mixer to obtain an externally added toner. To 4 parts of this toner and 96 parts of a Cu-Zn-ferrite carrier (average particle size = 100 μm) surface-coated with a resin containing methyl silicone, V
A developer was prepared by stirring and mixing with a mold mixer.

[Normal Durability Test] A copying machine 100 with a copying speed of 60 sheets / min, in which the above-mentioned developing agent is used as a starting developing agent, an externally added toner is used as a replenishing toner, and a negatively chargeable organic optical semiconductor photosensitive member is mounted. A live-action test of 000 sheets was conducted. still,
The actual shooting environment was a temperature of 23 to 25 ° C. and a humidity of 50 to 60% RH.

[High Temperature Storage Test] The developer and the replenishing toner (= external toner) were placed in a bottle, sealed with a cap, and stored for 10 days in an environment of a temperature of 45 ° C. and a humidity of 40 to 50% RH. Then, it was taken out to room temperature and cooled. Then, an actual copying test was performed on 10,000 sheets with the developer and the replenishment toner after being stored at a high temperature by the same method as the normal durability test. <Example 1> The kneading conditions of the extruder were as follows.

[0029]

[Table 2] ・ Number of screw threads: 3 threads ・ L / D 35 ・ Ta 80 ° C ・ Tk 182 ° C

The results of the actual copying test of the toner prepared under the conditions of Example 1 are shown in Table 1. The dispersion of carbon black is good, and the image characteristics such as image density and fog are continuously copied during both normal durability test and high temperature storage test. It was stable, and there was little contamination due to toner scattering in the copying machine after the actual copying test, which was good. <Example 2> The results of the actual copying test of the developer and the replenishment toner are shown in Table 1 in the same manner as in Example 1 except that the kneading conditions of the extruder were changed as follows, and the toner performance was good.

[0031]

[Table 3] ・ Number of screw threads: 3 threads ・ L / D 35 ・ Ta 100 ° C ・ Tk 185 ° C

<Comparative Example 1> Table 1 shows the results of the actual copying test of the developer and the replenishment toner as in Example 1 except that the kneading conditions of the extruder were changed as follows.
Fog was aggravated after over 10,000 sheets, and the amount of toner scattered inside the machine after actual copying was considerably large. Further, in the high temperature storage test, the fog worsened even after the initial stage, and the toner scattering inside the machine after actual copying was considerably problematic.

[0033]

[Table 4] ・ Number of screw threads: 3 threads ・ L / D 35 ・ Ta 160 ° C ・ Tk 192 ° C

Example 3 Table 1 shows the results of the actual copying test of the developer and the replenishment toner as in Example 1 except that the kneading conditions of the extruder were changed as follows. there were.

[0035]

[Table 5] ・ Number of screw threads: 2 ・ L / D 41 ・ Ta 80 ° C ・ Tk 187 ° C

[0036]

[Table 6]

[0037]

[Brief description of drawings]

FIG. 1 An example of a normal toner manufacturing flow

FIG. 2 is a schematic diagram of a continuous extruder.

FIG. 3 is an example of a cross-sectional view of FIG.

FIG. 4 shows an example of a kneading section screw (33) and a feeding section screw (30, 31)

[Explanation of symbols]

 1 Raw Material Supply Port 2 Vent Port 1 3 Vent Port 2 4 Cylinder Part 5 Barrel 6 Barrel C1 7 Barrel C2 8 Barrel C3 9 Barrel C4 10 Barrel C5 11 Barrel C6 12 Barrel C7 13 Barrel C8 14 Drive Part 15 Die 16 Exit 20 20 Raw Material Hopper 21 Screw feeder 24 Vacuum pump 30 First feeding part screw 31 Second feeding part screw 32 Third feeding part screw 33 First kneading part screw 34 Second kneading part screw 35 Refrigerant supply path 36 Refrigerant Supply device 40 Screw main body 41 Refrigerant supply path entry 42 Refrigerant supply path exit

Claims (5)

[Claims] 1. A method for producing a toner composition, which comprises mixing and mixing at least a resin and a colorant, kneading with a continuous extruder, and then pulverizing and classifying the mixture, wherein the barrel of the first kneading section of the continuous extruder is used. A method for producing a toner composition, wherein the relationship between the set temperature Ta (° C.) and the resin flow softening temperature Tm (° C.) is Ta ≦ Tm + 20. 2. The method for producing a toner composition according to claim 1, wherein the temperature of the kneaded product discharged from the outlet of the continuous extruder is equal to or higher than the flow end temperature of the resin. 3. The resin having a flow softening temperature of 80 ° C. or higher 14
The method for producing a toner composition according to claim 1, wherein the temperature is 5 ° C. or lower. 4. The first from the center of the material supply port of the continuous extruder.
The toner composition according to claim ₁ , wherein the relationship between the length L ₁ (mm) to the starting point of the kneading portion and the cylinder inner diameter D (mm) is L ₁ / D ≧ 5. Method. 5. The length L (mm) from the center of the material supply port of the continuous extruder to the tip of the cylinder and the cylinder inner diameter D.
The method for producing a toner composition according to claim 1, wherein the relationship of (mm) is L / D ≧ 20.