JPH0816795B2 - Toner manufacturing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention mainly relates to a method of manufacturing a toner for an electrophotographic copying machine, and a manufacturing apparatus thereof.

(Prior Art) Conventionally, in the method for producing a toner, carbon black and a thermoplastic resin powder are agitated and mixed, heated or a solvent is added to form a liquid, and the toner undiluted solution is spray-dried to obtain toner particles. In some cases, the kneaded product of the resin and the resin is crushed to an appropriate size and then melted or softened by a hot air flow type particle sizer to be spheroidized.

The toner particles thus formed are shown in FIG. 5 (1), in which carbon b and charge control agent c are mixed in the resin powder a. In order to prevent the particles from agglomerating, there is a method of coating the surface of the toner particles with non-adhesive fine particles d such as zinc oxide, silicon oxide and titanium oxide as shown in FIG. For example, there is Japanese Patent Publication No. 53-23700. Further, as shown in FIG. 5 (3), there is also a method of directly embedding or fixing fine particles such as carbon b and charge control agent c on the particle surface of the resin powder a for coating. Some of them use the impact type hitting means disclosed in JP-A-62-83029.

(Problems to be Solved by the Invention) As one of the points required as a toner for an electrophotographic copying machine, the toner is as close to a spherical shape as possible and has a narrow particle size range.
It has uniform particle size, is less likely to aggregate, and has good fluidity.
The toner satisfying these conditions has excellent dispersibility and enables high resolution copying. Therefore, as described above, in order to improve the dispersibility and fluidity by making the toner spherical, and in order to suppress the aggregation of the toner particles, zinc oxide, silicon oxide, titanium oxide as well as clay and calcium carbonate are formed on the toner particle surface. The non-adhesive particles are coated.

By the way, conventionally, in order to produce a toner, it has been necessary to start with a mixture of a resin powder and carbon etc., to add a solvent and to knead, and to grind and spheroidize the resulting mixture, and to perform many steps such as sieving. Moreover, not all toners produced in this way are satisfactory as products,
Finally, it is sorted by sieving, and the nonconforming ones are crushed for reuse or disposed of. Next, another point required for the toner is that carbon or the like is reliably held by the resin particles.
In other words, if the carbon particles are weakly retained in the resin particles, the carbon particles easily fall off from the resin particles and become detached, which may cause the image to become unclear and stain the white background. This is because.

Further, in the case where the toner is spray-dried from the raw material mixture using the fluidized granulation apparatus with a heated air flow, it is difficult to make the flow of the heated gas and the temperature in the furnace uniform throughout the furnace, and the particles are melted. In many cases, particles that condense or adhere to the furnace wall are fixed and melted, and the resulting product has insufficient spheroidization, and the carbon particles on the resin particles are weakly retained and easily fall off. Some products were not produced, and the product recovery rate was low.

On the other hand, in JP-A-62-83029, since fine particles such as carbon are embedded or fixed on the surface of the resin powder, carbon and the like are hardly dropped compared to the former, but the resin powder Embedded fine particles such as carbon,
Or, the particles of the resin powder itself may be crushed because a hitting means using an impact crusher is used to fix the particles. For example, it is extremely remarkable when a material having a relatively brittle property such as styrene resin is used as a raw material. Further, in order to cause the fine particles of carbon or the like to collide with the resin powder in the swirling airflow to some extent in the pulverizer, a considerable amount of carbon or the like exceeding the coating amount of carbon or the like on the resin powder particles as the toner is used. Needing. Moreover, resin powder, etc., including fine particles of carbon, easily adhere and accumulate on the inner wall of the crusher and the circulation pipe,
Therefore, extra raw materials are needed, resulting in waste of raw materials. In addition, in the action of colliding fine particles of carbon or the like with the resin powder in the swirling air current, it is difficult to uniformly coat each resin powder particle with fine particles of carbon or the like, and it is particularly excessive. There is a possibility that the adhered part will fall off later.

INDUSTRIAL APPLICABILITY The present invention is capable of efficiently producing an excellent toner for an electrophotographic copying machine, which is provided with sufficient elements as a toner and in which particles such as carbon do not fall off.

(Means for Solving the Problems) In the first aspect of the present invention, the toner raw material is put into a cylindrical container that rotates at a high speed, and the toner raw material is pressed against the inner peripheral surface of the rotating container by a centrifugal force. A powder layer fixed along the surface of the powder layer is formed, and at the same time, compression and friction by the stator disposed so as to be rotatable relative to the powder layer and mixing and agitation by the scraper are applied simultaneously and repeatedly. This is to soften the particle surface of the resin powder by the accompanying frictional heat, and to embed the particle such as carbon / charge control agent on the surface of the particle to cover the particle surface.

A second aspect of the present invention relates to an apparatus for carrying out the first aspect of the invention, in which a stator and a scraper are sequentially rotatably arranged in a rotating manner in a cylindrical container that rotates at high speed. The tip is formed so that the gap between the tip of the stator and the inner peripheral surface gradually narrows as the container rotates, giving strong compression and friction to the powder layer, and further detecting the temperature at the tip of the stator and scraper. And a temperature control means for controlling the temperature so that the resin powders do not fuse together due to excessive temperature.

(Operation) The most important operation in the present invention is to rotate the container A at a high speed in the direction of the arrow as shown in FIG. 3 and to centrifuge the resin powder as a raw material and the carbon / charge control agent etc. on the inner peripheral surface of the container A. By pressing it against B and thus simultaneously applying a compressive force and a frictional force to the powder layer F formed along the inner peripheral surface B by using the stator D having the arc-shaped curved surface E,
Fine particles such as carbon can be embedded on the surface of the resin powder particles. That is, the powder layer F of the raw material pressed and held against the inner peripheral surface B by the centrifugal force causes the stator C to form the gap C.
And is compressed from the thickness T to the thickness t, a strong compression and friction force is applied between the particles. By this compression and frictional force, the raw material particles are pressed and rubbed against each other, and the surface of the resin powder particles can be coated with fine particles such as carbon. In other words, by applying a strong pressure that is applied as compression / friction to generate a stress associated with this, on the particle side, a change in the crystal structure occurs in the surface layer of the particle, and the physical properties of the particle itself as a substance Changes in physical or chemical properties. In other words, a so-called mechanochemical reaction occurs, and a strong bonding force acts between the surfaces of both the resin powder particles and the particles of the carbon / charge control agent, that is, the particle surfaces are activated and the surfaces are fused. Is generated. In this way, the resin powder particles can be uniformly coated with fine particles such as carbon and a charge control agent. Moreover, since at least the surface of the resin powder particles is made difficult at least partially due to the heat generation phenomenon caused by compression / friction, when a compressive force is applied thereto, fine particles such as carbon / charge control agent are easily attached to the surface of the resin powder particles. And it can be effectively embedded.

As shown in FIGS. 4 (1) to (3), the resin powder particles are coated with carbon, the charge control agent, etc. on the surface of the resin powder particles a, such as carbon b, the charge control agent c, etc. The state shown in FIG. 1 where the particles adhere to the resin powder particles a and the next adhered fine particles b and c under strong pressure from outside.
After being pressed against the surface of (2) shown in Fig. 2, the fine particles b and c are embedded from the surface of the resin powder particles a to the inside as they are softened, and the softened resin component becomes fine particles b and c. The toner particles shown in FIG. 3C are also extruded from between and firmly hold fine particles such as carbon b and charge control agent c.

The resin powder particles that have been softened and that have been subjected to the action of stirring and mixing in addition to the strong compression and friction from the outside will also be spheroidized due to their synergistic effect. In addition to being able to uniformly coat the resin powder particles with carbon, a charge control agent, etc., it is also possible to adjust the amount of coated fine particles such as carbon with respect to the resin powder particles.

(Effects of the Invention) The present invention makes it possible to produce a toner coated with fine particles such as carbon by embedding fine particles such as carbon and a charge control agent on the surface of resin powder particles. It is held on and does not fall off easily. Moreover, due to the compression / friction and the rolling motion associated with stirring / mixing, spheroidization of the particles is promoted, and a toner having excellent fluidity can be obtained. Further, since it is possible to coat the resin powder particles with fine particles such as carbon extremely uniformly, it is possible to reduce the amounts of carbon and the charge control agent relative to the resin powder as compared with the conventional method. The ratio is, for example, 1 to 4% of the conventional carbon amount of 10 to 20% to the resin powder, and 1 to 2% of the charge control agent.
Can be significantly reduced to 0.1 to 0.2%, and particularly expensive charge control agents can be reduced, so that there is also an economical effect.

In addition, since it is not necessary to mix, knead, coarsely pulverize, mix and knead the resin powder and carbon / charge control agent, etc. in the conventional manufacturing method, and further sifting after pulverization, it is possible to improve efficiency in processing equipment and operation. , Performance can also be improved.

(Example) Next, the present invention will be described with reference to examples. 1 and 2 show a device for carrying out the present invention, in which a cylinder is provided at the upper end of a vertical rotation shaft 3 connected to a drive device 2 including an electric motor 2a and a transmission 2b fixed to a machine base 1. The casing 4 forming the processing chamber 5 is attached concentrically and is driven to rotate in the direction of the arrow in the figure. Also, casing 4
An electric motor using, for example, an inverter so that the raw material to be treated inside is pressed against the inner peripheral surface 4a by centrifugal force, and moreover, an appropriate centrifugal force is obtained according to the properties of the raw material inside. 2a can be controlled to a variable speed, and the rotation speed of the casing 4 can be freely adjusted and changed.

A cover 9 is provided around the outer periphery of the casing 4 so as to surround the casing 4 with a proper space, and an inlet 22 and an outlet 23 for cooling air are provided in the cover 9 to form a passage for cooling air on the outer periphery of the casing 4. The lower inlet 22 is provided with a filter 24, and the upper outlet 23 is connected to a wind turbine 29 via a valve 39. A heat radiating plate 20 is provided on the outer peripheral side of the casing 4 for the purpose of improving the cooling effect. Also,
On the side surface of the cover 9, a cooling water nozzle 19 arranged toward the outer periphery of the casing 4 and a drain port 21 associated therewith are provided below. The drainage from the drainage port 21 is sent to the storage tank 33, and is circulated and supplied again to the cooling water nozzle 19 by the pump 35 via the valve 40. Along with the cooling water nozzle 19, a ring-shaped partition plate 10 is arranged above the casing 4 in the cover 9 to prevent the cooling water from leaking above the casing 4. By changing the mounting position of the partition plate 10 and providing an appropriate gap between the partition plate 10 and the casing 4, the cooling air is uniformly applied to the entire surface of the casing 4 when the cooling air is sent to improve the cooling effect. can do. As described above, with respect to the cooling means of the casing 4, either water cooling or air cooling can be selected as required.

Next, inside the casing 4, the stator 6 and the scraper 7 are arranged with an appropriate gap maintained with respect to the inner peripheral surface 4a. The stator 6 and the scraper 7 are arranged in the rotational direction of the stator 6 and the scraper 7 in this order with a space therebetween, and are fixedly held by a support body 8 provided through the upper center of the casing 4. Has been done. The distal end portion 6a of the stator 6 has an arcuate curved surface, and its action surface gradually reduces the gap between the casing 4 and the inner peripheral surface 4a with respect to the rotation of the casing 4. A passage 16 for a heat medium or a refrigerant is provided inside the stator 6, the scraper 7, and the support 8. The passage 16 is connected to the supply pipe 14 and the discharge pipe 15, and is connected to the heat medium or refrigerant storage source 30 via the pump 34 and the valve 41. A temperature detector 25 is attached to the stator 6 and the scraper 7, and is connected to a temperature measuring device 26 in order to maintain the raw material in the processing chamber 5 within the optimum temperature range, and the temperature is adjusted according to the detected value.
That is, according to the detected value from the temperature detector 25, for example, the rotation speed of the casing 4 is immediately increased so that the rotation of the casing 4 is slowed as the temperature rises and becomes faster as the temperature falls. In addition to the change, the temperature control is performed by adjusting the supply amount of the heat medium and the refrigerant, or by adjusting the cooling water amount or the air amount. Note that one or more of these means can be selected at appropriate times.

In addition, in the support body 8, in addition to the passage 16 for the heat medium and the refrigerant, a raw material supply pipe 11, a product discharge pipe 12, and a transfer air introduction pipe.
13 and a liquid agent addition nozzle 17 and a gas supply nozzle 18 for air, an inert gas or the like are provided. The raw material supply pipe 11 is provided with a feeder 27, and the product discharge pipe 12 is provided with a collector 28, a wind turbine 29 and a valve 37.
However, a valve 38 is connected to the air introduction pipe 13, a storage source 31 is connected to the liquid agent addition nozzle 17 via a pump 36 and a valve 42, and a storage source 32 is connected to the gas supply nozzle 18 via a valve 43. .

The clearance between the stator 6 and the scraper 7 and the inner peripheral surface 4a of the casing 4 is, for example, 10 to 50 mm for the powder layer, 5 to 30 mm for the stator 6 side, and 1 to 1 for the scraper 7 side.
It is 2 mm.

With the above configuration, the raw material to be treated introduced from the raw material supply pipe 11 receives the addition of various liquid agents and the supply of the inert gas such as air and nitrogen in the processing chamber 5 as necessary, and the stator 6 and the scraper 7 By the above, the effects of compression friction and stirring and mixing are imparted, and toner particles in which fine particles such as carbon are embedded in the resin powder and coated are formed. Thus, after a predetermined time, the wind turbine 29 is operated, the valves 37 and 38 are operated, and the products introduced therein are put on the air introduced into the processing chamber 5 from the air introduction pipe 13 to the collector 28 from the product discharge pipe 12. It will be taken out by air transportation. Further, the temperature control in the processing chamber 5 which influences the quality of the toner as a product is usually performed by a temperature measuring device 26 connected to a temperature detector 25. In addition, by connecting a temperature control mechanism (not shown) to the temperature measuring device 26, it is possible to automate all means such as heating and cooling of the stator 6 and the scraper 7 and the inner wall surface 4a of the casing 4 from the change of the rotation speed of the casing 4. You can also

The optimum temperature for coating the resin powder particles with fine particles such as carbon varies depending on the type and component of the resin and the particle diameter, but in the case of ordinary toner resin powder,
It is in the range of 50-80 degrees Celsius. For example, as an experimental example, when a copolymer of styrene and acrylic was used as the raw material resin powder and the ratio of carbon black was 50: 1, the range was 50 to 55 degrees Celsius. The result of the experiment was very uniform and spherical, and a good product toner having excellent dispersibility and resolution was obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of the apparatus according to this embodiment, FIG. 2 is a sectional view taken along the line AA of FIG. 1, FIG. 3 is an explanatory view showing the outline of the operation of the stator of the present invention, and FIG. FIG. 5 is an explanatory view showing an outline of a toner manufacturing process in the invention, FIG. 5 is a sectional explanatory view of a conventional toner, and FIG. 6 is a main portion sectional view showing an example of a conventional apparatus. In the figure, 1 ... Machine stand, 2 ... Drive device, 3 ... Rotating shaft, 4 ... Casing, 4a ... Inner peripheral surface, 5 ... Processing chamber,
6 ... Stator, 7 ... Scraper, 9 ... Cover, 11 ...
… Raw material supply pipe, 12 …… Product discharge pipe, 13 …… Air introduction pipe,
16 …… passage, 19 …… cooling water nozzle, 25 …… temperature detector,
A ... container, B ... inner peripheral surface, C ... gap, D ... stator, E ... curved surface, F ... powder layer, a ... resin powder, b ...
... carbon, c ... charge control agent, d ... non-adhesive fine particles.

Claims (7)

[Claims] 1. A toner raw material such as a thermoplastic resin powder, carbon, a charge control agent, etc. is mechanically imparted and agitated and mixed, and the resin powder is softened by frictional heat at the time of the action to form on the surface of the particle. In the method of embedding fine particles such as carbon / charge control agent and the like, the toner raw material is put into a cylindrical container A that rotates at a high speed, and the toner raw material is pressed against the inner peripheral surface B of the rotary container A by centrifugal force. The raw material powder layer F fixedly held along the inner peripheral surface B is formed, and the compression friction and the mixing and stirring are performed by the stator D and the scraper arranged so as to be rotatable relative to the powder layer F. A method for producing a toner, which comprises simultaneously and repeatedly applying fine particles such as carbon and a charge control agent to the surface of resin powder particles. 2. A stator 6 and a scraper 7 are arranged in a cylindrical casing 4 rotating at a high speed so as to be rotatable relative to each other in the rotation direction, and the distal end portion 6a of the stator 6 and the inner peripheral surface are rotated as the casing 4 rotates. The tip 6a on the side of the stator 6 is formed in such a shape that the gap with the 4a is gradually narrowed, and the temperature detector 25 is provided at both tips of the stator 6 and the scraper 7, and a temperature control means interlocking with this is provided. A toner manufacturing apparatus characterized by being configured by adding. 3. A variable speed electric motor 2a as the temperature control means.
The toner manufacturing apparatus according to claim (2), wherein the rotational speed of the casing 4 is freely changeable by using the above, and the generation of frictional heat associated with the friction between the stator 6 and the scraper 7 and the raw material powder layer is adjusted. 4. The temperature control means according to claim 2, wherein a passage 16 is formed inside the stator 6 and the scraper 7 so as to connect to both ends thereof, and the passage 16 is connected to a heat medium or refrigerant storage source 30. The toner manufacturing apparatus described. 5. The toner production according to claim 2, wherein a gas supply nozzle 18 is provided in the casing 4 as the temperature control means and is connected to a storage source 32 for air, inert gas or the like. apparatus. 6. As the temperature control means, a casing 9 is surrounded by a cover 9 with a proper space around the outside, and a cooling water nozzle is provided in the cover 9 toward the outer peripheral wall of the casing 4.
The toner manufacturing apparatus according to claim (2), which is provided with 19. 7. The temperature control means, wherein a proper space is provided around the outer periphery of the casing 4 and is surrounded by a cover 9, and the space is connected to a wind turbine 29 as a passage for cooling air. 2. The toner manufacturing apparatus according to the item 2).