JPH07313896A - Method for pulverizing resin and device therefor - Google Patents

Abstract

PURPOSE:To efficiently remove the heat generated in crushing and to produce finer resin powder by introducing a coarse-powder resin into the atmosphere into which liq. carbon dioxide is jetted, mixing the resin with the dry ice solidified by jet and crushing the mixture. CONSTITUTION:Liq. carbon dioxide in a cylinder 7 is jetted into a mixing tank 1 from a nozzle 3 and solidified into dry ice. A coarse-powder resin is introduced onto the dry ice from a hopper 4, dropped to the bottom of the tank along with the snow-like dry ice and mixed with the dry ice by a feeder 10, and the mixture is powdered. The mixture is supplied to a crusher 2 by the feeder 10 through a mixture delivery line 11 and sheared into a fine powder with about 5mum size. At this time, the dry ice acts as an assistant to crush the resin, and the resin is not flattened but pulverized. Since the resin is mixed with the low-temp. dry ice, the resin heated by crushing is directly cooled by the dry ice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin pulverizing method and apparatus for producing resin fine powder, and more particularly to a resin fine pulverizing method capable of efficiently removing heat generated by pulverization to produce finer powder. The present invention relates to a method and an apparatus thereof.

[0002]

2. Description of the Related Art For example, a toner used for developing an electrostatic latent image in a copying machine or the like is one in which a resin is used as a powder. A crusher is used to powder the resin. Generally, a high-speed rotary crusher has a rotary blade and a fixed blade, and the raw material resin is sheared and powdered by these blades.

When resin is crushed by such a crusher, heat is generated. Since the resin is easily softened or melted by heat, if the heat is not removed, the resin will be buried in the gap between the blades or the powder will draw a string. Therefore, conventionally, the crusher is cooled from the casing side, or cold air is blown into the gap between the blades to remove heat. Further, as the diameter of the powder becomes smaller, the powder will pass through the gap between the blades together with the air, and it will not be possible to grind further smaller, so there is a limit to the diameter that can be ground.

[0004]

The size of the resin powder varies depending on the application, but in recent years, the demand for finer powder has increased. In the case of toner, if the powder size can be reduced, it is expected that the resolution of a copying machine or the like will be improved.

However, it is difficult to produce fine powder with a high-speed rotary crusher. The reason is that when the diameter of the powder becomes small, the amount of the powder passing through the gap between the fixed blade and the rotary blade becomes large, and the sheared and compressed powder generates heat, melts and adheres to the gap to prevent pulverization. In the method of cooling the crusher from the outside in order to cool the heat generation, the rotary blade inside cannot be cooled, so that a sufficient cooling effect cannot be obtained. Further, cold air cannot provide a sufficient cooling effect with respect to the amount of heat generation.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a resin pulverizing method and an apparatus therefor capable of efficiently removing heat generated by pulverization to produce finer powder.

[0007]

In order to achieve the above object, the present invention is to put a resin of coarse powder into an atmosphere in which liquid carbon dioxide is sprayed, mix the resin and dry ice solidified by spraying, This mixture is pulverized to make the resin fine powder.

In the apparatus, a nozzle for injecting liquid carbon dioxide and a hopper for injecting coarse powder resin are connected to a mixing tank, and a feeder for delivering a mixture of the resin and dry ice solidified by injection into the mixing tank. And a crusher for crushing the mixture sent from the feeder into a fine powder.

The mixture being ground may be cooled with the carbon dioxide vaporized by the jet.

[0010]

The applicant has tried sending liquid nitrogen instead of cold air, but when water in the air turns into ice and the resin is crushed with the ice, the resin does not flatten and powder. I understood. On the other hand, when liquid carbon dioxide was used, it was discovered that not only carbon dioxide gas (vaporized carbon dioxide) acts as a refrigerant but also the resin becomes powder when the resin is crushed together with the generated dry ice.

With the above structure, the injected liquid carbon dioxide undergoes a phase change due to adiabatic expansion in the atmosphere, and a part thereof is solidified and the rest is vaporized. Although the dry ice solidified by the injection is snow-like, it is mixed with the input coarse powder resin to form a powder mixture. When the mixture is pulverized, the resin generates heat, but since the low temperature dry ice is mixed with the resin, the heat generated by the pulverization is directly cooled by the dry ice. Therefore, the resin does not reach a high temperature, and the softened or melted resin does not fill the gap between the blades and the powder does not pull the thread. Further, the resin is sprinkled with dry ice to increase the particle size, and is crushed without passing through the blade gap.

The carbon dioxide vaporized by the injection is low temperature (-
79 ° C.), the mixture during grinding can be cooled. This increases the utilization efficiency of liquid carbon dioxide.

In the step of crushing the mixture, dry ice also works as an auxiliary agent for crushing the resin, which is efficient.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1 (a), the resin pulverizing apparatus of the present invention mainly comprises a mixing tank 1 for mixing resin and dry ice, and a pulverizer 2 for pulverizing the mixture into fine powder. It consists of

Above the tank body of the mixing tank 1, a nozzle 3 for injecting liquid carbon dioxide, a hopper 4 for injecting coarse powder resin, and a gas delivery line 5 for delivering gaseous carbon dioxide.
And a recovery line 9 described later are connected. A liquid carbon dioxide cylinder 7 is connected upstream of the nozzle 3 via a control valve 6. A raw material line (not shown) for supplying a raw material resin of coarse powder is connected to the upstream side of the hopper 4. The mixing tank 1 has a substantially cylindrical shape, and when viewed from above, it has a substantially circular shape as shown in FIG. The nozzle 3 is introduced into the mixing tank 1 from the tangential direction of the circle so that the jet flow is along the inner circumference of the mixing tank 1. The introduction positions of the hopper 4 and the collection line 9 are located outside the circle,
The resin and the recovered powder are introduced immediately downstream of the jet flow from the nozzle 3. The outlet 5a to the gas delivery line 5 is located at the center of the circle. Below the tank body of the mixing tank 1, there is provided a feeder 10 that mixes resin and dry ice and sends out a fixed amount of the mixture. Feeder 1
A mixture delivery line 11 is connected to 0.

The mixing tank 1 and the crusher 2 are connected by a gas discharge line 5 and a mixture delivery line 11. Also,
The crusher 2 is connected to the classifier 8 via a fine powder discharging line 12, and a product discharging unit 15 is connected to the downstream of the classifier 8 via a bag filter 14 equipped with a suction blower 13. A recovery line 9 from the classifier 8 is connected to the mixing tank 1.

The crusher 2 is a high-speed rotary shearing crusher having a rotary blade that rotates at high speed and a fixed blade. As shown in FIG. 4, the high-speed rotary shearing crusher is provided with a multi-stage fixed blade 42 on the inner periphery of a crushing chamber 41 formed in a substantially cylindrical shape, and alternates with the fixed blade 42 in the crushing chamber 41. The rotary blade 43 is provided so that. A drive motor 44 that rotationally drives the rotary blade 43 is provided immediately below the crushing chamber 41. The outer circumference of the crushing chamber 41 is surrounded by a cooling jacket 45. An inlet 46 opening to the side is provided at the bottom of the crushing chamber, and the gas delivery line 5 and the mixture delivery line 11 are connected to this inlet 46. An outlet 47 that opens laterally is provided at the top of the crushing chamber 41, and the fine powder delivery line 12 is connected to the outlet 47.

When viewed from above, the crusher 2 is as shown in FIG. That is, the inlet 46 is introduced in the tangential direction and the outlet 47 is led out in the tangential direction on the opposite side. The positional relationship between the fixed blade 42 and the rotary blade 43 is shown in FIGS. 6 and 7. As shown in FIG. 6A, the fixed blade 42 is provided at a predetermined interval in the inner peripheral wall 61 of the crushing chamber 41 and in the circumferential direction of the crushing chamber 41, and protrudes radially inward to form the rotary blade 43 of the rotor 62. The tooth-shaped portion 63 extends to the vicinity. On the other hand, the rotary blade 43 includes a rotor 62 and a tooth-shaped portion 64 that is provided on the outer periphery of the rotor 62 at predetermined intervals in the circumferential direction and protrudes radially outward. Between the corresponding tooth-shaped portions 63 of the fixed blades 42 which are vertically adjacent to each other, the protrusion is smaller than the tooth-shaped portion 63, and the tooth-shaped portion 63 is concave. The rotary blade 43 is at the same height position as this concave portion, and the tooth-shaped portion 64 of the rotary blade 43 is provided.
However, it just enters this concave portion and forms a gap. FIG. 6A shows a state in which the tooth-shaped portion 63 of the fixed blade 42 and the tooth-shaped portion 64 of the rotary blade 43 are staggered with each other, and the rotor 62 is rotated to overlap each other as shown in FIG. 6B. It becomes a state.

FIGS. 7A and 7B are side views of the same states as FIGS. 6A and 6B, respectively. As shown, the fixed blade 42 and the rotary blade 43
Are alternately arranged in multiple rows above and below.

In the present embodiment, the gap between the rotary blade 43 and the fixed blade 42 is 0.1 to 0.2 mm.
The pressure of the liquid carbon dioxide cylinder 7 is 60 kg / cm ² . The ambient temperature is normal temperature (20 ° C.), and the inside of the mixing tank 1 is atmospheric pressure (about 1 kg / cm ² ). The size of the coarse resin powder is 50 to 100 μm.

Next, the operation of the embodiment will be described.

FIG. 3 is a graph of carbon dioxide pressure and enthalpy. Liquid carbon dioxide in the cylinder 7 is at point A, that is,
In liquid phase. By opening the control valve 6, liquid carbon dioxide is injected from the nozzle 3 into the tank of the mixing tank 1.
The jetted liquid carbon dioxide follows a line with a constant entropy due to adiabatic expansion, and reaches a point B at which the atmospheric pressure is reached, that is, a solid / vapor phase. The injected liquid carbon dioxide undergoes a phase change due to adiabatic expansion in the atmosphere and a part is solidified, and the rest is vaporized. The temperature at this point B is -78.9 ° C. The dry ice solidified by the spray becomes snow-like.

The pressure of the liquid carbon dioxide cylinder 7 is 25 kg.
/ Cm ² and the temperature is −15 ° C., the change is from point C to point D.

From the hopper 4, coarse powder resin is put on the solidified dry ice. The coarse powder resin drops to the bottom of the tank together with snow-like dry ice, and is mixed by the feeder 10. The mixture of both becomes powdery. The size of this mixture is of the order of a few millimeters. As shown in FIG. 2, the mixture has a structure in which a large number of coarse powder particles 22 of finer resin are contained in a dry ice powder particle 21 of several mm. The feeder 10 supplies this mixture to the inlet 46 of the crusher 2 in a constant amount via the mixture delivery line 11.

In the crusher 2, the rotary blade 43 is rotated at a high speed, and the mixture is sheared by the rotary blade 43 and the fixed blade 42 into fine powder of about 5 μm. At this time, dry ice acts as an auxiliary agent for crushing the resin, so that the resin is not flatly crushed and becomes fine powder. This fine powder moves to the outlet 47. The crushed resin generates heat, but since the low temperature dry ice is mixed with the resin, the heat generated by this crushing is directly cooled by the dry ice. Therefore, the resin does not reach high temperature,
The softened or melted resin does not fill the gap between the blades and the powder does not pull the thread.

The carbon dioxide vaporized by the injection is discharged to the crusher 2 via the gas discharge line 5. The low temperature of this carbon dioxide allows the mixture to be cooled during grinding.

The fine powder discharged from the outlet 47 of the crusher 2 is classified by the classifier 8, and the large particles are collected in the mixing tank 1 through the collecting line 9. The fine powder having the required particle size or less is removed by the bag filter 14, and the product having the required particle size is dispensed from the product dispensing unit 15.

[0029]

The present invention exhibits the following excellent effects.

(1) Since the heat generated by pulverization is removed and the resin does not reach a high temperature, it is possible to produce fine powder. At that time, dry ice is effective because it serves as a refrigerant and a grinding aid.

(2) Since the resin is sprinkled with dry ice and the particle size becomes large, it is crushed into fine powder without passing through the gap between the blades.

[Brief description of drawings]

1A and 1B show an embodiment of the present invention, FIG. 1A is a block diagram of a resin pulverizing apparatus, and FIG. 1B is a plan view of a mixing tank.

FIG. 2 is an enlarged view of the particles of the mixture.

FIG. 3 is a carbon dioxide pressure-enthalpy diagram.

FIG. 4 is a cross-sectional view of a high speed rotary shear grinder.

5 is a plan view of the high speed rotary shearing grinder of FIG. 4. FIG.

FIG. 6 is a plan view showing a fixed blade and a rotary blade of the high speed rotary shearing type pulverizer of FIG.

7 is a side sectional view showing a fixed blade and a rotary blade of the high-speed rotary shearing type pulverizer of FIG.

[Explanation of symbols]

 1 Mixing tank 2 Crusher 3 Nozzle 4 Hopper 7 Liquid carbon dioxide cylinder 10 Feeder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryotaka Yoshioka 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office

Claims (3)

[Claims] 1. A method in which a resin of a coarse powder is put into an atmosphere in which liquid carbon dioxide is sprayed, the resin and dry ice solidified by spraying are mixed, and the mixture is pulverized to form a fine powder of the resin. Method for finely pulverizing resin. 2. A nozzle for injecting liquid carbon dioxide and a hopper for injecting a coarse powder resin are connected to a mixing tank, and a feeder for delivering a mixture of the resin and dry ice solidified by injection is provided in the mixing tank. A resin fine pulverization device, which is provided with a pulverizer for pulverizing the mixture sent from the feeder into fine powder. 3. The resin finely pulverizing method according to claim 1, wherein the mixture being pulverized is cooled with carbon dioxide vaporized by the jetting.