JP2013163349A - Extrusion molding apparatus and method for manufacturing conductive resin molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extrusion molding apparatus capable of stably manufacturing, in manufacturing of a pipe-shaped conductive resin molded article by use of a whiskerless resin raw material, the pipe-shaped conductive resin molded article without breakage of the molded article.SOLUTION: An extrusion molding apparatus 1 includes: an extruder 10 which melts and plasticizes a whiskerless resin raw material obtained by kneading a thermoplastic resin and a conductive material and extrudes the resulting molten resin; an extrusion die 20 which molds the molten resin into a cylindrical shape; a sizing device 30 which sizes the molten resin while hardening it by cooling to form the conductive resin molded article; and a take-up machine which takes up the conductive resin molded article. The sizing device 30 includes a sizing die 31 having a resin flow path, a cooling unit 33 for cooling the molten resin through the resin flow path; a vacuum unit 32 for sucking the molten resin toward the wall surface of the resin flow path; a temperature detection unit S for detecting the temperature of the resin flow path; and a temperature control unit 34 for controlling cooling conditions in the cooling unit based on the detection result of the temperature detection unit.

Description

  The present invention relates to an extrusion molding apparatus for manufacturing a pipe-shaped conductive resin molded body by an extrusion molding method and a method for manufacturing a conductive resin molded body, and in particular, a developing sleeve used in an electrophotographic image forming apparatus is a whiskerless. The present invention relates to a technique suitable for production using resin raw materials.

In general, an electrophotographic image forming apparatus (printer, copying machine, facsimile, etc.) forms an electrostatic latent image by irradiating (exposing) laser light based on image data to a charged photoreceptor. The developing device visualizes the electrostatic latent image by attaching toner to the electrostatic latent image to form a toner image. Then, the toner image is directly or indirectly transferred to the paper, and then fixed by heating and pressing to form an image on the paper.
The developing device includes a developing roller that conveys charged toner to a photoconductor. The developing sleeve, which is the surface layer of the developing roller, is composed of a conductive resin molded body for transporting charged toner.

  For example, an extrusion molding method is used for manufacturing a pipe-shaped conductive resin molded body such as a developing sleeve. For example, Patent Literatures 1 and 2 disclose an extrusion molding device having a vacuum sizing device having a cooling function. Has been. In addition, as a raw material of the conductive resin molded body, a thermoplastic resin obtained by melting and kneading a conductive powder such as carbon black or a conductive whisker (acicular or fibrous conductive material) such as carbon fiber in a thermoplastic resin. A composition is used (for example, patent documents 3-5).

  FIG. 1 is a diagram showing an example of a conventional extrusion molding apparatus used for plastic extrusion. As shown in FIG. 1, the extrusion molding apparatus 5 includes an extruder 10, an extrusion die 20, a sizing apparatus 40, and a take-up machine (not shown). The extrusion die 20 is provided with a resin flow path 21 for supplying molten resin formed by heating and melting in the extruder 10 to an adjacent sizing device 40 while forming it into a pipe shape.

  In the extrusion molding device 5, the resin raw material R introduced from the hopper 13 is melted and plasticized while being conveyed by the screw 12 in the cylinder 11, and becomes a molten resin M. The molten resin M is extruded from the extrusion die 20 in a state where it is easily deformed at a high temperature. The molten resin M extruded from the extrusion die 20 is transported while being controlled to a predetermined size and shape by the sizing device 40 by the leading end side being taken out by a take-up machine (not shown), and simultaneously cooled and hardened. Through these steps, a pipe-shaped conductive resin molded body C as a final molded body can be manufactured through an intermediate molded body (a molded body that is not completely cured).

In the extrusion molding apparatus 5 shown in FIG. 1, a so-called vacuum sizing apparatus that performs sizing by a vacuum sizing method is employed as the sizing apparatus 40.
That is, the sizing device 40 includes a vacuum unit 42 that evacuates the inside of the sizing die 41. By evacuating the vacuum chamber 422 formed in the sizing die 41 by the vacuum pump 421, the molten resin M (including the intermediate molded body) is sucked into the inner surface 41a of the sizing die 41 and conveyed in this state. , Controlled to a predetermined size and shape.

  The sizing device 40 includes a cooling unit 43 that cools the molten resin M through a sizing die 41. A cooling medium (for example, cooling water) cooled to a constant temperature (for example, about room temperature) by the cooling device 431 circulates in the cooling chamber 432 formed in the sizing die 41, thereby cooling the molten resin M through the sizing die 41. Is done.

  Note that the cooling unit 43 only circulates and cools cooling water at a constant temperature, so that the temperature of the inner surface 41a of the sizing die 41, that is, how much molten resin is in contact with the inner surface 41a of the sizing die 41. Whether it is cooled by temperature is not controlled separately.

JP-A-6-106604 JP 2001-301008 A JP 2003-183461 A JP 2003-156902 A JP 2002-231051 A

  By the way, when manufacturing a conductive resin molding, it is also attempted to use a resin raw material called whiskerless using conductive powder such as carbon black instead of the resin raw material using the conductive whisker described above. However, when a whiskerless resin raw material is used in the conventional extrusion molding method, it has been found that the conductive resin molded body C is broken before being taken up by the take-up machine, so that the production is difficult.

  An object of the present invention is to stably produce a pipe-shaped conductive resin molded body without breaking the molded body when a pipe-shaped conductive resin molded body is produced by extrusion molding using a whiskerless resin raw material. It is providing the manufacturing method of the extrusion molding apparatus which can be manufactured, and a conductive resin molding.

An extrusion apparatus according to the present invention includes at least an extruder for extruding a molten resin formed by melting and plasticizing a whiskerless resin raw material obtained by kneading a thermoplastic resin and a conductive material,
An extrusion die for forming the molten resin extruded from the extruder into a cylindrical shape;
A sizing device that cools and cures the molten resin extruded from the extrusion die to form a conductive resin molded body, and
A take-out machine for picking up the conductive resin molded body sized by the sizing device, and an extrusion molding device comprising:
The sizing device includes a sizing die having a cylindrical resin flow path for moving the molten resin,
A cooling section for cooling the molten resin through a resin flow path provided in the sizing die;
A vacuum section for sucking the molten resin toward the wall surface of the resin flow path;
A temperature detection unit for detecting the temperature of the resin flow path cooled by the cooling unit;
A temperature control unit that controls a cooling condition in the cooling unit based on a detection result of the temperature detection unit.

A method for producing a conductive resin molded body according to the present invention is a method for producing a conductive resin molded body using the extrusion molding apparatus,
A first step in which a whiskerless resin raw material obtained by kneading a thermoplastic resin and a conductive material is melted and plasticized by the extruder to extrude the molten resin and molded into a cylindrical shape by the push die;
In accordance with the cooling conditions set by the temperature control unit based on the detection result of the temperature detection unit, the molten resin extruded from the extrusion die is cooled and cured by the sizing device and sized to form a conductive resin molded body. And a second step of forming.

  According to the present invention, when a pipe-shaped conductive resin molded body is manufactured by an extrusion molding method using a whiskerless resin raw material, the pipe-shaped conductive resin molded body is not broken during the manufacturing. Can be stably produced. In particular, in the field of electrophotographic image forming apparatuses, it has become possible to stably produce a developing sleeve used in a developing apparatus using a whiskerless resin material.

It is a figure which shows an example of the conventional extrusion molding apparatus used for plastic extrusion. It is a figure which shows the resin clogging which arises when using a whiskerless raw material. It is a figure which shows roughly the whole structure of the extrusion molding apparatus which concerns on embodiment of this invention.

The present invention relates to an extrusion molding apparatus for producing a cylindrical conductive resin molded body using a resin raw material containing a thermoplastic resin and a conductive material.
Hereinafter, the background to the present invention will be described.
First, the inventors tried to manufacture a pipe-shaped conductive resin molded body C using a whiskerless resin raw material R by using an extrusion molding apparatus 5 shown in FIG. For the whiskerless resin raw material R, a kneaded mixture of 12 nylon and carbon black powder was applied.
As a result, it was found that the conductive resin molded body C was broken before being taken up by the take-up machine, making it difficult to manufacture. Therefore, when the extrusion molding device 5 was examined when the conductive resin molded body C was broken, the molten resin formed a bulge as indicated by B in FIG. 2 between the extrusion die 20 and the sizing device 40. It was noticed that this caused resin clogging. That is, it is considered that the resin clogging B is a stopper that prevents the molten resin M from being conveyed, and an excessive tensile stress is generated, so that the conductive resin molded body C is broken.

  Therefore, the reason why the resin clogging B occurs is examined, and when the whiskerless resin raw material R is used, the extrusion die is compared with the case where the conductive resin molded body C is manufactured using the whisker-containing resin raw material R. It was determined that the viscosity of the molten resin M immediately after being extruded from 20 was low. From this, the occurrence mechanism of the resin clog B was inferred as follows.

  That is, when the resin raw material R containing whiskers is used, the viscosity of the molten resin M extruded from the extrusion die 20 is high (for example, 200 to 500 Pa · s), and the curing proceeds further before entering the sizing die 41. When passing through the vicinity of the entrance of the sizing die 41, the conveyance is not hindered (the state in which the sizing die 41 can be conveyed at an expected speed while sliding).

  On the other hand, when the whiskerless resin raw material R is used, the viscosity of the molten resin M extruded from the extrusion die 20 is low (for example, 80 to 150 Pa · s), which is sufficient to enter the sizing die 41. Therefore, even when passing near the entrance of the sizing die 41, the state of being easily deformed is maintained. Therefore, when it passes through the sizing die 41, it is pulled by the take-up machine, and is excessively stretched, so that the conveyance speed becomes slower than a predetermined value. Moreover, when the molten resin M hardens | cures, it will adhere to the sizing die 41 and it is also considered that conveyance becomes temporarily impossible. On the other hand, the molten resin M is pushed out from the extrusion die 20 one after another. The present inventor has inferred that the resin clogging B may be formed as a result of the balance between the conveyance and the curing of the molten resin M being lost.

  Accordingly, in order to maintain the balance between the conveyance and extrusion of the molten resin M, the present inventor has cured to the extent that the resin clogging B does not occur when the molten resin M passes near the entrance of the sizing die 41. The conclusion was reached that it is important (the viscosity is high). Then, the present inventor breaks the conductive resin molding by controlling the state (viscosity) of the molten resin M while maintaining the cooling temperature constant while monitoring the temperature of the inner surface 41a of the sizing die 41. The present invention was found by obtaining the knowledge that it can be manufactured without using the same. That is, the inventor of the present invention thought to prevent the occurrence of the resin clogging B by positively cooling the low-viscosity molten resin to increase the viscosity of the molten resin. As described above, the present invention monitors the molten state of the resin based on the temperature detection in the sizing die so that the molten resin can be conveyed so as not to cause clogging of the resin.

Here, the extrusion molding apparatus according to the present invention will be described with reference to FIG. An extrusion molding apparatus 1 shown in FIG. 3 is one of the extrusion molding apparatuses according to a preferred embodiment of the present invention. The extrusion molding apparatus 1 shown in FIG. 3 includes an extruder 10, an extrusion die 20, a sizing device 30, and a take-up machine (not shown). As will be described later, the sizing device 30 includes a sizing die 31 having a cylindrical resin flow path 311 that moves the molten resin, and a cooling unit 33 that cools the resin flow path 311 provided in the sizing die 31. The vacuum part 32 that sucks the molten resin toward the wall surface 311a of the resin flow path 311; the temperature detection part S that detects the temperature of the resin flow path 311 cooled by the cooling part 33; and the detection result of the temperature detection part S The temperature control unit 34 for controlling the cooling conditions in the cooling unit 33 is provided.
3 monitors the molten state of the resin supplied to the sizing die 31 in the vicinity of the inlet so that the temperature can be controlled so that the viscosity does not cause clogging of the resin. That is, the temperature control unit 34 compares the preset cooling temperature near the inlet of the sizing die 31 with the detection result of the temperature detection unit S1 that detects the temperature near the inlet of the sizing die 31 and based on the comparison result. Then, the cooling condition of the cooling unit 33A is controlled so that the temperature of the temperature detection unit S1 becomes a preset cooling temperature.

Hereinafter, the extrusion apparatus 1 shown in FIG. 3 will be described in detail and specifically.
The extruder 10 is, for example, a single screw type extruder, and includes a screw 12 disposed inside the cylinder 11, a hopper 13 that supplies the resin material R to the cylinder 11, and a heater 14 that heats the cylinder 11. The output of the heater 14 is controlled so that the temperature in the cylinder 11 is equal to or higher than the melting temperature of the resin raw material R (for example, the melting point +50 to 80 ° C.). In the extruder 10, the resin material R introduced from the hopper 13 is melted and plasticized while being conveyed by the screw 12 in the cylinder 11, and becomes a molten resin M.

  The extrusion die 20 is a die (die) that is attached to the tip (downstream in the extrusion direction) of the extruder 10 and molds the molten resin M into a pipe shape. A resin flow path 21 for forming the molten resin M into a pipe shape is formed in the extrusion die 20. The molten resin M conveyed from the extruder 10 is formed into a pipe shape by the extrusion die 20 and is extruded in a state where it is easily deformed at a high temperature.

  The sizing device 30 is a so-called vacuum sizing device that performs sizing by a vacuum sizing method. The sizing device 30 includes a sizing die 31, a vacuum unit 32, a cooling unit 33 (33A to 33C), a temperature detection unit S (S1 to S3), and a temperature control unit 34.

  The sizing die 31 is a die that performs so-called sizing that adjusts to a predetermined size and shape while cooling the molten resin M. The sizing die 31 has a cylindrical resin flow path 311 for moving the molten resin M. As will be described later, the wall surface 311a of the resin flow path 311 provided in the sizing die 31 is provided with a temperature detection unit S (S1 to S3) that is a sensor for detecting the temperature. Specifically, a thermocouple or the like is used. It has been. The wall surface 311a of the resin flow path 311 is desirably formed with a coating layer made of, for example, nickel Teflon (registered trademark). Thereby, since the slipperiness | liquidity at the time of conveying molten resin M improves, a favorable conveyance state is ensured and it is preferable also from a viewpoint of generation | occurrence | production prevention of resin clogging B.

  The vacuum unit 32 includes a vacuum pump 321 and a vacuum chamber 322 connected to the vacuum pump 321. The vacuum chamber 322 is formed inside the sizing die 31 so as to communicate with the resin flow path 311 through a suction hole. The vacuum pump 321 exhausts the vacuum chamber 322 to reduce the pressure. Thereby, the molten resin M moving in the sizing die 31 is sucked into the wall surface 311 a of the resin flow path 311 of the sizing die 31.

  The cooling unit 33 includes a first cooling unit 33A that cools a region near the entrance of the sizing die 31 (first region), and a second cooling that cools a region near the center of the sizing die 31 (second region). The unit 33B includes a third cooling unit 33C that cools the region (third region) near the exit of the sizing die 31. The first cooling unit 33A to the third cooling unit 33C include cooling devices 331A to 331C and cooling chambers 332A to 332C connected to the respective cooling devices 331A to 331C.

  In FIG. 3, what has a some cooling part is shown as a preferable form of this invention. That is, FIG. 3 is provided with three cooling units 33 of the first cooling unit 33A, the second cooling unit 33B, and the third cooling unit 33C along the conveying direction of the molten resin M. The extrusion molding apparatus according to the present invention has at least one cooling unit 33, and the cooling unit 33 may be disposed near the inlet of the sizing die 31 so that the molten resin M is rapidly cooled in the vicinity of the inlet of the sizing die 31. preferable. The vicinity of the entrance of the sizing die 31 is an area through which the molten resin passes in 0 to 15 mm and 0.3 to 0.4 sec from the entrance.

  In this way, by arranging a plurality of cooling portions 33 from the inlet of the sizing die 31 to the outlet, the temperature of the resin flow path 311 is increased stepwise from the inlet of the sizing die 31 to the outlet. A distribution can be formed. As a result, the conductive resin molded body C having a good surface state can be manufactured.

The cooling chambers 332A to 332C constituting the cooling units 33A to 33C are arranged in parallel from the inlet of the sizing die 31 to the outlet, that is, along the conveying direction of the molten resin M. And cooling device 331A-331C is provided corresponding to each of cooling room 332A-332C.
The cooling devices 331A to 331C have a water pump, a cooling tower, a cooling tank, etc. (all not shown), and circulate a cooling medium (for example, cooling water) at a predetermined temperature in the cooling chambers 332A to 332C at a predetermined flow rate. At the same time, the returned cooling medium is cooled to a predetermined temperature. The cooling devices 331A to 331C can circulate cooling media having different temperatures.

As described above, in the extrusion molding machine according to the present invention, a temperature detection sensor represented by a thermocouple or the like is provided as the temperature detection unit S on the wall surface 311a of the resin flow path 311 provided in the sizing die 31. .
3 includes a plurality of temperature detection units S1 to S3, and the temperature detection units S1 to S3 are the temperatures of the inner surface of the sizing die 31, that is, the wall surface 311a of the resin flow path 311. It is a sensor represented by a thermocouple or the like that detects The temperature detection unit S is embedded in the vicinity of the wall surface 311 a of the resin flow path 311 of the sizing die 31. The temperature detectors S1 to S3 respectively control the temperatures of the first region (near the entrance of the sizing die 31), the second region (near the center of the sizing die 31), and the third region (near the exit of the sizing die 31). To detect.

The temperature control unit 34 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (all not shown). Based on the detection results (output signals) of the temperature detection units S1 to S3, the temperature control unit 34 cools the cooling conditions (for example, the temperature and flow rate of the cooling medium) in the first cooling unit 33A to the third cooling unit 33C. To control.
For example, CH-401 manufactured by Taitec Corporation can be applied to the temperature detection units S1 to S3 and the temperature control unit 34.

Specifically, the temperature control unit 34 controls the cooling conditions in the first cooling unit 33A to the third cooling unit 33C so that the temperature detected by the temperature detection units S1 to S3 becomes a preset cooling temperature. To do. That is, the temperature control unit 34 compares the preset cooling temperature with the detection result of the temperature detection unit, and based on the comparison result, sets the temperature of the temperature detection unit in advance. Thus, the cooling condition by the cooling unit 33 is controlled.
When the conductive resin molded body C is manufactured, a temperature range that does not cause resin clogging in each of the first to third regions is set in the temperature control unit 34 in advance as a cooling temperature.

  For example, when the detection results of the temperature detection units S1 to S3 are higher than a preset cooling temperature, the temperature control unit 34 is cooled by the first cooling unit 33A to the third cooling unit 33C so that the cooling capacity is increased. Control the conditions. Moreover, when the detection result of temperature detection part S1-S3 is lower than the preset cooling temperature, the temperature control part 34 is cooled by the first cooling part 33A to the third cooling part 33C so that the cooling capacity is lowered. Control the conditions. As described above, since the temperature control unit 34 controls the first to third regions to have a predetermined cooling temperature, the conveyed molten resin M is positively cooled to increase the viscosity. Occurrence of clogging is avoided.

As described above, the extrusion molding apparatus 1 includes an extruder 10 that melts and plasticizes a whiskerless resin raw material R obtained by kneading a thermoplastic resin and a conductive material, and extrudes the molten resin M, and is extruded from the extruder 10. Extrusion die 20 that molds molten resin M into a cylindrical shape, sizing device 30 that cools and cures molten resin M extruded from extrusion die 20 and forms a conductive resin molding, and sizing A take-up machine (not shown) for taking up the conductive resin molded body C sized by the apparatus 30 is provided.
The sizing device 30 includes a sizing die 31 having a cylindrical resin flow path 311 that moves the molten resin M, and a cooling unit that cools the molten resin M via the resin flow path 311 provided in the sizing die 31. 33, a vacuum part 32 for sucking the molten resin M toward the wall surface 311a of the resin flow path 311, a temperature detection part S for detecting the temperature of the resin flow path 311 cooled by the cooling part 33, and a temperature detection part S And a temperature control unit 34 for controlling the cooling condition (for example, the temperature or flow rate of the cooling medium) in the cooling unit 33 based on the detection result of

  According to the extrusion molding apparatus 1, the cooling temperature when the molten resin M is cooled and cured in the sizing apparatus 30 can be kept constant at a predetermined cooling temperature. That is, even when the whiskerless resin raw material R is used, the molten resin M can be easily cured to such an extent that the conveyance is not hindered. Therefore, the extrusion molding apparatus 1 is useful for producing a pipe-shaped conductive resin molded body C having desired properties (conductivity (surface resistivity), rebound resilience, dimensions, shape, surface state, etc.). is there.

Hereinafter, a method for producing a pipe-shaped conductive resin molding C using a whiskerless resin raw material R obtained by kneading a thermoplastic resin (for example, 12 nylon) and a conductive material (for example, carbon black). explain about.
For the resin raw material R, for example, a thermoplastic resin and a conductive material are melt-kneaded with a twin-screw kneader, then the obtained strand is cooled in a water tank, crushed into pellets with a pelletizer, and dried with a vacuum dryer (85 ° C. × 10 hours) can be applied. Moreover, you may apply the resin raw material R which added antioxidant, the compatibilizing agent, the coupling agent, etc. other than a thermoplastic resin and an electroconductive material.

  The user sets the cooling temperature by the first cooling unit 33A to the third cooling unit 33C. At this time, the cooling temperature by the first cooling unit 33A is a temperature at which resin clogging does not occur (a temperature at which the conveyance of the molten resin M in the sizing die 31 is not hindered), that is, the molten resin M is moderate in the vicinity of the inlet of the sizing die 31. It is set as the temperature which hardens. The cooling temperature by the second cooling unit 33B and the third cooling unit 33C is a temperature at which desired properties (for example, a surface state) can be obtained in the conductive resin molded body C.

The cooling temperature varies depending on the size and shape of the sizing die 31, the type of the resin raw material R, the heating temperature in the extrusion die 20, the extrusion speed of the molten resin M, and the like. it can. When the conductive resin molded body C is manufactured under the same manufacturing conditions, it is only necessary to set the cooling temperature in the same manner. Therefore, the conductive resin molded body C having desired properties can be easily manufactured.
The temperature control unit 34 sets the cooling conditions in the first cooling unit 33A to the third cooling unit 33C so that the temperature detected by the temperature detection units S1 to S3 becomes the cooling temperature preset by the user. It will be.

In the present invention, the temperature control unit 34 causes the temperature of the inner surface of the sizing die 31 to increase stepwise from the upstream side in the extrusion direction (sizing die 31 inlet side) to the downstream side (sizing die 31 outlet side). Moreover, it is preferable to control the cooling conditions in the respective cooling units 33A to 33C.
By controlling the cooling conditions in the cooling units 33A to 33C as described above, excessive cooling of the molten resin M in the sizing die 31 can be avoided, and the resin molded body can be prevented from shrinking excessively. That is, by preventing excessive shrinkage of the resin molded body, there is no occurrence of a gap between the resin molded body and the wall surface of the sizing die 31 in the sizing die 31. Suction of the body can be performed stably. Moreover, since the resin molding which is the molten resin M is cooled appropriately, the resin molding does not adhere to the wall surface of the sizing die 31, and the resin molding can be smoothly conveyed in the sizing die. .
In this way, by controlling the cooling conditions in the cooling units 33A to 33C so that the temperature of the inner surface increases stepwise from the inlet side to the outlet side of the sizing die 31, the molten resin M in the sizing die 31 is controlled. It is preferable because suction and stable conveyance can be performed with a good balance.

When the whiskerless resin material R is charged into the extruder 10, the molten resin M is extruded from the extrusion die 20 disposed at the tip of the extruder 10 (first step).
And in the sizing apparatus 30, while the molten resin M is cooled and hardened | cured by a vacuum sizing method, a dimension and a shape are controlled (2nd process).

In the second step, the molten resin M is cooled according to the cooling conditions set by the temperature control unit 34. Since the temperature control unit 34 sets the cooling condition in the first cooling unit 33A based on the detection result of the temperature detection unit S1, the cooling temperature near the entrance of the sizing die 31 is kept constant. Therefore, when the molten resin M extruded from the extrusion die 20 passes near the entrance of the sizing die 31, the molten resin M is reliably cured to such an extent that the conveyance is not hindered.
For example, when a whiskerless resin raw material R obtained by kneading 12 nylon and carbon black is used, the viscosity of the molten resin M immediately after being extruded from the extrusion die 20 is 80 to 150 Pa · s. By increasing the viscosity to 200 Pa · s or more before passing through the vicinity of the entrance of the resin, conveyance of the molten resin M is not hindered.

  Moreover, since the temperature control part 34 sets the cooling conditions in the 2nd cooling part 33B and the 3rd cooling part 33C based on the detection result of temperature detection part S2, S3, the resin flow path 311 of the sizing die 31 is used. A desired temperature distribution is formed on the wall surface 311a. Thereby, the desired property (for example, surface state) is obtained in the conductive resin molding C.

Thus, even when the whiskerless resin raw material R is used by using the extrusion molding apparatus 1, the desired properties (conductivity (surface resistivity), rebound resilience, dimensions, shape, surface state) Etc.) can be produced.
Further, by applying the obtained conductive resin molded body C as a developing sleeve of an electrophotographic image forming apparatus, a stable high quality image can be formed.

  When the resin raw material R containing whiskers is used as in the prior art, since the molten resin M extruded from the extrusion die 20 is appropriately cured, a sizing device 40 (see FIG. 1) circulates a constant temperature cooling medium. There was no problem as long as it could be cooled. On the other hand, when the whiskerless resin raw material R is used, as described above, the temperature at the wall surface 311a of the resin flow path 311 of the sizing die 31 (particularly the temperature near the inlet of the sizing die 31) is kept constant. It is extremely useful to positively cure the molten resin M.

[Example]
In the examples, as the resin raw material R, 12 nylon (crystalline nylon, amorphous nylon, or a kneaded product of the two) and a kneaded product of acetylene black were used. 12 nylon is a polyamide resin obtained by ring-opening polycondensation of lauryl lactam. Acetylene black is carbon black obtained by thermally decomposing acetylene gas, has a small amount of surface functional groups, and has high conductivity. The melting temperature of the resin raw material R was 160 to 170 ° C., and the viscosity at 240 ° C. was 45 to 65 Pa · s.

This resin raw material R was put into the extruder 10, the heating temperature in the extruder 10 and the extrusion die 20 was set to 220 ° C., the resin raw material R was melted and plasticized, and the molten resin M was formed into a pipe shape.
And the cooling temperature of the 1st field (10-25 mm on the basis of an entrance) in sizing device 30 is 15-20 ° C, and the cooling temperature of the 2nd field (35-50 mm on the basis of entrance) is 20-25 ° C, The cooling temperature of the third region (90 to 120 mm with reference to the inlet) was set to 25 to 30 ° C., the molten resin M was cooled and cured, and the size and shape were regulated.
Through the above steps, a pipe-shaped conductive resin molded body C having an outer diameter of φ16.5 mm and a thickness of 0.15 mm was produced.

  About the obtained pipe-shaped conductive resin molding C, when surface resistivity, rebound resilience, dimensions, and surface state were measured or observed, the conductive resin molding C obtained using the resin raw material R containing whiskers was obtained. It was almost equivalent. In addition, in the electrophotographic image forming apparatus in which the conductive resin molding C is applied as a developing sleeve, a stable and high-quality image can be formed.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be changed without departing from the gist thereof.

For example, the resin raw material R is not limited to those exemplified in the examples, and 6 nylon, 11 nylon, 66 nylon, 6T nylon, 9T nylon, 610 nylon, 612 nylon, thermoplastic elastomer, and the like can be applied.
In this case, the heating temperature in the extruder 10 and the extrusion die 20 and the cooling temperature in the sizing device 30 are appropriately set according to the type of the resin raw material R to be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Extrusion molding apparatus 10 Extruder 11 Cylinder 12 Screw 13 Hopper 14 Heater 20 Extrusion die 21 Resin flow path 30 Sizing apparatus 31 Sizing die 32 Vacuum part 33 Cooling part 33A 1st cooling part 33B 2nd cooling part 33C 3rd Cooling unit 34 Temperature control unit S, S1, S2, S3 Temperature detection unit 311 Resin flow path 311a Wall surface 321 Vacuum pump 322 Vacuum chamber 331A, 331B, 331C Cooling device 332A, 332B, 332C Cooling chamber C Conductive resin molding M Melting Resin R Resin raw material

Claims (8)

At least an extruder for melting and plasticizing a whiskerless resin raw material obtained by kneading a thermoplastic resin and a conductive material, and extruding the molten resin;
An extrusion die for forming the molten resin extruded from the extruder into a cylindrical shape;
A sizing device that cools and cures the molten resin extruded from the extrusion die to form a conductive resin molded body, and
A take-out machine for picking up the conductive resin molded body sized by the sizing device, and an extrusion molding device comprising:
The sizing device includes a sizing die having a cylindrical resin flow path for moving the molten resin,
A cooling section for cooling the molten resin through a resin flow path provided in the sizing die;
A vacuum section for sucking the molten resin toward the wall surface of the resin flow path;
A temperature detection unit for detecting the temperature of the resin flow path cooled by the cooling unit;
An extrusion apparatus comprising: a temperature control unit that controls a cooling condition in the cooling unit based on a detection result of the temperature detection unit.   The extrusion apparatus according to claim 1, wherein the cooling unit is provided in the vicinity of an inlet through which the molten resin is supplied to the sizing die.   The temperature control unit compares a preset cooling temperature with a detection result by the temperature detection unit, and the temperature detection unit sets the temperature detection unit so that the temperature of the temperature detection unit becomes a preset cooling temperature. The extrusion apparatus according to claim 1 or 2, wherein the cooling condition is controlled.   The extrusion apparatus according to any one of claims 1 to 3, wherein a plurality of the cooling units and the temperature detection units are provided.   The said temperature control part controls the cooling conditions in each said cooling part so that the temperature of the inner surface of the said sizing die may rise in steps toward the downstream from the upstream in the extrusion direction. 5. The extrusion molding apparatus according to 4.   The extrusion apparatus according to any one of claims 1 to 5, wherein a coating layer for improving slipperiness is formed on an inner surface of the sizing die.   The extrusion molding apparatus according to any one of claims 1 to 6, wherein the extrusion molding apparatus molds a developing sleeve used in an electrophotographic image forming apparatus. A method for producing a molded body made of a conductive resin using the extrusion molding apparatus according to any one of claims 1 to 7,
A first step in which a whiskerless resin raw material obtained by kneading a thermoplastic resin and a conductive material is melted and plasticized by the extruder to extrude the molten resin and molded into a cylindrical shape by the push die;
In accordance with the cooling conditions set by the temperature control unit based on the detection result of the temperature detection unit, the molten resin extruded from the extrusion die is cooled and cured by the sizing device and sized to form a conductive resin molded body. And a second step of forming the conductive resin molded body.

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