JPH0929840A - Manufacture of heat shrunk thermoplastic endless belt material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an endless belt material given by heating shrinkage at a uniform resistance level even after heating without a folding seam by blowing a high-temperature gas to the outer periphery of a tube shaped by a mandrel, and then weak orienting the tube by a second mandrel further increased in outer diameter. SOLUTION: The outer periphery of a melted tube extruded by an annular die 3 mounted at an extruder 2 is temperature regulated by gases blown by temperature regulating rings 6, 6', 6", the gas controlled at the supply pressure and flow rate by a supply tube 14 is continuously supplied to bring the inside of the tube into contact with the first mandrel 5 to be temperature regulated to be solidified while always setting the inner pressure to a predetermined pressure. Further, gases temperature regulated from rings 6"', 6"" are blown to be brought into contact with the second mandrel 7 increased in outer diameter than that of the first mandrel 5 to be shaped, then passed between a nip rolls 10 arranged at each predetermined interval in the circumferential direction of a support tube rod 4, and drawn while maintaining a tube-like state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention covers drums, rollers and the like used in photoconductor devices such as electrophotographic copying machines and laser printers, intermediate transfer devices, transfer separation devices, charging devices and developing devices. The present invention relates to a method for producing an endless belt material having heat shrinkability.

[0002]

2. Description of the Related Art Conventionally, in a photoconductor device such as an electrophotographic copying machine, an intermediate transfer device, a transfer separation device, a charging device, a developing device, etc., a sheet is wound around a drum or a shrinkable tube having a fold is used. It is used by covering the roller.

When a drum in which such a sheet is wound around a drum is used, the range of use on the drum is limited, and it is necessary to always start from a fixed position. Therefore, a sensor for detecting the position is required. The seat life will be shortened due to the increasing number of places used. Further, if a shrinkable tube having a fold is used by covering it, the fold is transferred to an image to cause an image defect, and the resistance to heating is considerably difficult to control because of a large heat shrinkage rate.

As a method for producing such an endless belt, the present inventors have proposed a method for producing an endless belt material in JP-A-1-228823 and JP-A-4-255332. However, when the endless belt using this manufacturing method is used by being wound around a drum as described in JP-A-4-313757, there is almost no heat shrinkage, so that it does not fit on the drum and is used in an electrophotographic copying machine. However, there is a problem that image unevenness occurs and a clear image cannot be obtained.

The present invention has been made in view of the above problems, and its object is to have no folds and
Further, the present invention provides a method for producing an endless belt material having a uniform resistance level after heating and having heat shrinkability.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have blown a high temperature gas to the outer peripheral surface of the tube shaped by the first mandrel to soften the tube to some extent. In this condition, the second mandrel, which has an outer diameter larger than that of the first mandrel, allows the tube to be weakly stretched, allowing heat shrinkage without creases and fitting to drums, rollers, etc., and even resistance level after heating. I found something.

That is, in the method for producing an endless belt material of the present invention, a thermoplastic resin composition is melted and extruded in a tube shape downward from an annular die mounted on an extruder, and a temperature-controlled gas is formed on the outer peripheral surface of the tube. In the vicinity of the start of the contact of the first mandrel with the temperature of the first mandrel being controlled by continuously supplying and removing the gas whose supply pressure and supply flow rate are controlled inside the tube. A temperature-controlled gas is blown onto the outer peripheral surface of the tube, and a second mandrel whose outer diameter is larger than that of the first mandrel and whose temperature is controlled is provided below the outer surface of the tube between the first mandrel and the second mandrel. It has a heat-shrinkable property, which is characterized by spraying a temperature-controlled gas on the surface and then continuously taking it while keeping the tube shape and cutting it into a sliced shape. It is a manufacturing method of the endless belt member that.

The resin composition applied in the present invention is basically a resin composition containing a thermoplastic resin as a main material, and includes polyethylene (high density, medium density, low density, linear low density),
Propylene ethylene block or random copolymer,
Rubber or latex components such as ethylene / propylene copolymer rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer or hydrogenated derivatives thereof, polybutadiene, polyisobutylene,
Polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyimide, liquid crystalline polyester, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene sulfide, polybisamide triazole, polybutylene terephthalate, polyetherimide, Polyetheretherketone, acrylic, polyvinylidene fluoride, polyvinyl fluoride, ethylene tetrafluoroethylene copolymer, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether copolymer, acrylic, acrylic acid alkyl ester copolymer,
One or a mixture of polyester ester copolymer, polyether ester copolymer, polyether amide copolymer, polyurethane copolymer and the like is used.

[0009] Further, as an additional component, various fillers,
For example, calcium carbonate (heavy, light, colloidal) talc,
Mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, glass fiber, glass beads, bentonite, montmorillonite, asbestos, hollow glass beads, graphite, molybdenum dioxide. Other fillers such as titanium oxide, carbon fiber, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder, chaff, graphite, metal powder, conductive metal oxide, organic metal compound, organic metal salt, etc. , As additives: antioxidants (phenolic, sulfur-based, etc.), lubricants, various organic / inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants,
A neutralizing agent, a foaming agent, a plasticizer, a copper damage inhibitor, a flame retardant, a cross-linking agent, a flowability improving agent, etc. can be added. The above-mentioned composition can be produced by using a conventional kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender, a plastograph, and a kneader, if desired, with the additional components.

Usually, each component is kneaded with an extruder or the like to form a pelletized compound, which is then processed. However, in a special case, each component is directly supplied to a molding machine and the composition is kneaded with the molding machine. It is also possible to form while molding. As shown in FIG. 1, FIG. 2, and FIG. 3, the tube manufacturing apparatus 1 for an endless belt material includes an annular die 3 mounted on an extruder 2 and a supporting tube rod 4.
The upper part of the support tube 4 is fixed coaxially, and
The mandrel 5 and the second mandrel 7 are coaxially fixed.

Between the annular die 3 and the mandrels 5 and 7, temperature control rings 6, 6 ', 6 "and 6"' are coaxial with the support tube 4.
, 6 ″ ″ are arranged, and a plurality of sets of nip rolls 10, 10 are arranged below the mandrel. Nip roll 1
0 and 10 are composed of a plurality of inner rolls 8 and 8 arranged on the outer periphery of the support tube 4 below the second mandrel 7, and outer rolls 9 and 9 arranged corresponding to these inner rolls 8 and 8. Become.

The support tube 4 is provided with a supply pressure / supply flow rate control gas continuous supply mechanism 11 and a heating medium supply mechanism 12, 12 'in the mandrel. The supply pressure / supply flow rate control gas continuous supply mechanism 11 includes a supply pipe 14 that passes through the inside of the support pipe 4 and opens to a blowout port 13, and a discharge pipe 16 that passes through the inside of the support pipe rod 4 and opens at a blow-in port 15. And consists of.

Heat medium supply mechanism 12, 1 in the mandrel
2'passes through the inside of the supporting rod 4 and feed pipes 18 and 18 'which are opened to the inflow ports 17,17' in the first and second mandrels 5,7, and inside the supporting rod 4. First and second
The discharge pipes 20 and 20 'are open to the outlets 19 and 19' in the mandrels 5 and 7.

When the annular die 3 is oriented upward with respect to the extruder 2, the tube is deformed by its own weight and folds or the like are generated, so the annular die 3 must be attached downward. The structure of the annular die 3 is not particularly limited, but a spiral die is preferable from the viewpoint of uniform tube wall thickness. Further, it may be a single-layer die or a multi-layer die, and in the case of a multi-layer die, the resin composition of each layer may be the same or different.

Although the first mandrel 5 is located below the annular die 3 at a distance, it may be connected below the annular die 3 or may penetrate the annular die 3 to be connected to an external structure. Good. The distance between the die lip of the annular die 3 and the position where the molten tube first contacts the first mandrel 5 is 20.
It is desirable that the length is not less than mm and not more than 500 mm. If it is less than 20 mm, the tube is abruptly deformed between the die lip and the first mandrel 5, so that the tube is easily cut and continuous production becomes difficult. On the other hand, if it is 500 mm or more, the die lip and the first
In the tubes between the mandrels 5, a large proportion of the molten tubes having a small melt tension occupy an unstable tube shape, which makes stable continuous production difficult.

The second mandrel 7 is spaced below the first mandrel 5 but may be connected below the first mandrel 5 and penetrates the first mandrel 5 to an external structure. You may connect. As shown in FIG. 3, the relationship between the diameter D ₁ of the die lip of the annular die 3 and the diameter D ₂ of the first mandrel 5 is D ₂ = 3D ₁ or less, D ₂ = 0.5D ₁
It is desirable to be above, preferably D ₂ = 1.5D
₁ or less and a D ₂ = 0.6D ₁ or more, more preferably D ₂ = 0.99D ₁ or less, D ₂ = 0.8D ₁ or more. When the diameter D ₂ of the first mandrel 5 is 3D ₁ or more, sagging due to stick slip occurs at the position where the molten tube contacts the first mandrel 5, and a tube with a uniform wall thickness in the longitudinal direction is obtained. Disappear. On the other hand, D ₂
Is less than 0.5 D ₁ , the molten tube does not contact the first mandrel 5 at the same time in the circumferential direction, and a tube having a uniform wall thickness cannot be obtained.

Most preferably, as shown in FIG.
From the diameter D _{1 of the} die lip, the diameter D _{2 of} the first mandrel 5
It is advisable that the tube is made slightly smaller and the tube is brought into complete contact with the first mandrel 5 to solidify the temperature. The peripheral edge of the first mandrel 5 on the annular die 3 side is preferably chamfered at 2 mmR or more and 20 mmR or less. Diameter D ₂ of the first mandrel 5
As shown in FIG. 3, the relationship between the second mandrel 7 and the diameter D ₄ is preferably D ₄ = 1.1D ₂ or more and D ₄ = 3D ₂ or less, and more preferably D ₄ = 1.2D ₂ Above, D ₄
= 2D ₂ or less. Diameter of second mandrel 7 D ₄ =
When it is less than 1.1 D ₂ , the stretching effect does not occur and the shrinkage after the heat treatment is insufficient. On the other hand, when D ₄ = 3D ₂ is exceeded, stretching becomes large, which becomes a factor of deteriorating the resistance distribution.

The peripheral edge of the second mandrel 7 on the side of the first mandrel 5 is preferably chamfered in the range of 2 mmR to 20 mmR. The length of the first and second mandrels 5, 7 in the longitudinal direction is preferably 10 mm or more, but 20 mm.
It is preferably not less than 3 times the diameter D ₁ of the die lip.
If it is less than 10 mm, the die lip and the first mandrel 5
The pressure limitation in the space surrounded by the molten tube and the tube becomes unstable, and the circularity deteriorates. When the diameter of the die lip is 3 times or more of the diameter D ₁ , the frictional force between the solidified tube and the side surfaces of the first and second mandrels 5 and 7 increases, and the nip rolls 10 positioned after the first and second mandrels 5 and 7 are positioned. The tube that has been solidified between and is plastically deformed, and the wall thickness of the tube becomes uneven, and the tube does not pass through the mandrel.

The surface condition of the first and second mandrels 5, 7 is preferably so-called satin finish treatment having irregularities of 0.3 μ or more, preferably 0.5 μ or more 25
It is preferable that the thickness is not more than μ, and more preferably not less than 1 μ and not more than 10 μ. When the unevenness is less than 0.3 μ, the tubes in the molten state and the softened state have the first and second mandrels 5, 7
A stick-slip is generated at the position of contact with the tube, and it becomes impossible to obtain a tube with a uniform wall thickness in the longitudinal direction.
If it is above, a scratch will occur on the inner surface of the tube and the pressure control in the space surrounded by the die lip, the first mandrel 5 and the molten tube becomes unstable.

The material of the first and second mandrels 5, 7 is preferably metal, ceramics, wood, cloth, etc., preferably metal or ceramics. Plastic materials such as Teflon are not preferable because stick-slip easily occurs. The first and second mandrels 5, 7 are either perfect circles and have a constant longitudinal diameter, or reverse taper having a large diameter on the side close to the die lip and a gradient of 5/100 or less. It may be.

The surface temperature of the first and second mandrels 5 and 7 is preferably below the glass transition point (Tg) or below the melting point (Tm), preferably below Tg-10 ° C or below Tm-10 ° C. . If it is Tg or Tm or more, stick slip occurs on the first and second mandrels 5 and 7, and it becomes impossible to obtain a tube having a uniform wall thickness in the longitudinal direction.

Well-known means can be adopted for adjusting the surface temperature of the first and second mandrels 5, 7; however, from the viewpoint of temperature control accuracy and temperature control ability, the temperature inside the first and second mandrels 5, 7 can be adjusted. It is desirable to circulate a conditioned heat medium. The space surrounded by the die lip, the first mandrel 5 and the tube in the molten state needs to be continuously supplied and discharged with a gas whose supply pressure and supply amount are controlled, and when the space is in a sealed state. , A slight unevenness in take-up occurs that does not affect the uniformity of the wall thickness of the tube, or the tube in the molten state between the die lip and the first mandrel 5 does not contact at the same time in the circumferential direction. , A tube with a uniform wall thickness cannot be obtained.

Air and nitrogen are preferable as the gas to be continuously supplied, and the temperature of the gas to be supplied is preferably constant. The distance L between the position of the first mandrel 5 and the second mandrel 7 is preferably 50 mm or more and 3000 mm or less. When it is less than 50 mm, the tube does not soften between the first mandrel 5 and the second mandrel 7, and does not pass through the second mandrel 7. On the other hand, when it is 3000 mm or more, the distance between the first mandrel 5 and the nip roll 10 becomes long, so that the tube cannot be stably pulled off, and the roundness of the tube deteriorates.

As shown in FIGS. 1 and 3, in the vicinity of the position where the molten tube contacts the first mandrel 5, a cross section taken along a vertical plane passing through the center of the annular die 3 and the center of the first mandrel 5. With regard to the above, regarding the point where the molten tube contacts the first mandrel 5, the point A is defined as the point on the tube immediately above this point A which is higher than the point A, and the annular die 3 passes through the point A.
A point on a line parallel to a line passing through the center of the and the center of the first mandrel 5 is defined as a point C.

On the left side facing the first mandrel 5,
A line AC connecting points A and C and a line AB connecting points A and B
When ∠ CAB formed by and the clockwise is − and the counterclockwise is +, ∠ CAB is preferably + 20 ° or less and −45 ° or more, preferably + 10 ° or less and −30 ° or more, and more preferably 0 ° or less − It is good to set it as 20 degrees or more. When ∠CAB becomes + 20 ° or more, the molten tube does not come into contact with the first mandrel 5 at the same time in the circumferential direction, and a tube having a uniform wall thickness cannot be obtained. On the other hand, if ∠CAB is less than −45 °, stick-slip occurs on the first mandrel 5 and a tube having a uniform wall thickness cannot be obtained.

A nip roll is used as a means for continuously pulling the solidified tube without making a crease. Inner rolls 8 are attached to the inside of the continuously moving tube around the supporting tube rod 4 at least at two or more places, and outer rolls corresponding to the inner rolls 8 are covered with a rubber elastic body on the outer side of the tube. 9 is arranged, and the tube is continuously drawn by sandwiching the tube with the inner roll 8 and the outer roll 9.

The driving force for pulling the tube is the outer roll 9
It is more preferable to give it to the side from the viewpoint of simplicity and operability of the device. The tube taken up by the nip roll 10 can be taken up while the gas is retained in the tube when some deformation is allowed, and taken off from the nip roll 10 when slight deformation is not allowed. The tube may be cut into a desired length in a ring shape.

The wall thickness of the tube obtained according to the present invention is 10 μm.
It is preferably 2000 μ or more and 2000 μ or less, and more preferably 20 μ or more and 1000 μ or less. If the wall thickness of the tube is less than 10 μm, it is plastically deformed when it is taken up by the nip roll 10, and a tube having a uniform wall thickness cannot be obtained. If it is 2000 μm or more, cooling on the first mandrel 5 becomes difficult.

As described above, the temperature of the outer peripheral surface of the molten tube extruded from the annular die 3 mounted on the extruder 2 is controlled by the gas blown from the temperature control rings 6, 6 ', 6 ", and the supply pipe 14 is supplied. While continuously supplying a gas whose supply pressure and supply flow rate are controlled so that the inside pressure is always a predetermined pressure, the inside of the tube is brought into contact with the first mandrel 5 for temperature control and solidification, and further 6 ″ ′, 2nd with a larger outer diameter than the 1st mandrel 5 by spraying a temperature-controlled gas from 6 ""
The mandrel 7 is brought into contact with the mandrel 7 for shaping, and then the support tube 4
Since it is drawn while passing through the nip rolls 10 arranged at predetermined intervals in the circumferential direction while maintaining the tubular shape, there is no seam or crease even if the taken tube is cut into a sliced shape.

[0030]

Next, specific examples of the present invention will be described.

Example 1 4 with a die lip outer diameter of 104 mmφ and a lip gap of 1 mm
A support tube rod 4 that penetrates the annular die 3 that is a spiral annular die is chamfered with an outer diameter of 100 mmφ, a side length of 50 mm, and a peripheral edge of the annular die 3 side of 5 mmR so that the alumina ceramics has a surface irregularity of 2 μ. The first mandrel 5 made of steel sprayed on the above is attached at a position 100 mm from the end face of the annular die 3. Also, with the same specifications as the first mandrel 5,
The second mandrel 7 having an outer diameter of φ200 is replaced with the first mandrel 5
It is attached at a position 500 mm below the lower end of.

Further, at a position 100 mm below the lower end of the second mandrel 7, a rubber inner roll 8 of 10 mmφ,
8 is provided, and 50 mmφ rubber outer rolls 9 and 9 which are located outside the tube corresponding to these two inner rolls 8 and 8 respectively and are driven by a motor (not shown) are provided. The outer roll 9 and the outer roll 9 form nip rolls 10, 10.

Melt flow rate (MFR) 4.6g
/ 10 min (280 ° C.) polycarbonate (Mitsubishi Gas Chemical Co., Ltd. Iupilon E-2000) 83 parts by weight, MFR 4.32 g / 10 min (230 ° C.) polybutylene terephthalate (Mitsubishi Chemical Co., Novador 5020) 17 parts by weight and 16 parts by weight of acetylene black (manufactured by Denki Kagaku Co., Ltd.) having a specific surface area of 70 m ² were kneaded and granulated using a twin-screw extruder with a vent, and the obtained pellets were 280 from an extruder of φ50 mm. Extruded at a temperature of ℃, 150 ℃ air from the temperature control ring 6 close to the annular die 3 and 80 ℃ from the temperature control ring 6 ^′ located 20 mm above the upper end of the first mandrel 5, the first mandrel. Temperature control ring 6 ^″ located 20 mm below the upper end of 5
80 ° C. air is blown from the supply pipe 14 and 0.03 kg / cm ² , 1 NL / min air is supplied from the supply pipe 14, and a molten tube having ∠CAB of −5 ° is supplied from the supply pipe 18 to 85 ° C. The warm water of 1 is brought into contact with the first mandrel 5 which is circulated at 2 L / min, and the temperature control ring 6 at a position 50 mm below the lower end of the first mandrel 5.
^'''Than 0.99 ° C. air temperature control ring 6 position above 300mm from the upper end of the second mandrel ^7''''than 200 ° C.
Each of which is blown with air, and hot water of 85 ° C. is circulated from the supply pipe 18 ^′ to the second mandrel 7 which is circulated at 2 L / min. Got

An aluminum tube having an outer diameter of φ198 was inserted into the obtained tube, left for 1 hour in an oven whose temperature was controlled at 150 ° C., and then taken out of the oven for natural cooling. As a result, an endless belt-coated drum fitted to an aluminum tube was created. The endless belt portion of the obtained coated drum was cut open and the diameter in the longitudinal direction was measured. As a result, the change was ± 0.5.
mm, and the change in wall thickness in the circumferential direction was ± 5%.
In addition, using RA8340A manufactured by Advantest, JIS
Based on K-6911, the volume resistance was measured using a sample having a thickness of 150 μm. However, the electrode is made of conductive silicone rubber, and the force for pressing the electrode against the sample is 4 kg. As a result, the volume resistance in the longitudinal direction and the circumferential direction is 1 × 10 ^{9 to} 9
It was in the range of × 10 ⁹ Ω · cm and was sufficiently satisfactory as an endless belt coating drum for an electrophotographic copying machine.

Example 2 A supporting tube bar 4 which penetrates an annular die 3 which is a four-threaded annular spiral die having an outer diameter of a die lip of 74 mmφ and a lip gap of 1 mm, has an outer diameter of 71 mmφ, a side face length of 50 mm, and an annular die 3 side. The peripheral edge is chamfered at 5 mmR, and a first steel mandrel 5 sprayed with alumina-based ceramic so as to have surface irregularities of 2 μ is attached at a position 100 mm from the end surface of the annular die 3. A second mandrel 7 having the same specifications as the first mandrel 5 and an outer diameter of φ142 is attached at a position 500 mm below the lower end of the first mandrel 5.

Further, at a position 100 mm below the lower end of the second mandrel 7, a rubber inner roll 8 having a diameter of 10 mm,
8 is provided, and 50 mmφ rubber outer rolls 9 and 9 which are located outside the tube corresponding to these two inner rolls 8 and 8 respectively and are driven by a motor (not shown) are provided. The outer roll 9 and the outer roll 9 form nip rolls 10, 10.

Melt flow rate (MFR) is 4.0 g
/ 10 min (230 ° C.) polyvinylidene fluoride (Kiner 720 manufactured by Mitsubishi Chemical Corporation) was used to extrude at a temperature of 220 ° C. from an extruder of φ50 mm, and air at 120 ° C. was blown from the temperature control ring 6 close to the annular die 3. , 50 ° C. air from the temperature control ring 6 ^′ located 20 mm above the upper end of the first mandrel 5 and 50 ° C. air from the temperature control ring 6 ^″ located 20 mm below the upper end of the first mandrel 5. While spraying each, 0.03k from the supply pipe 14
g / cm ² , 1 NL / min of air is supplied, ∠ CAB
The molten tube having a temperature of −5 ° is brought into contact with the first mandrel 5 in which warm water of 30 ° C. is circulated at 2 L / min from the supply pipe 18, and the temperature at a position 50 mm below the lower end of the first mandrel 5 is reached. adjustment ring 6 ^'''of 100 ° C. from the air, the second mandrel 7 the upper end than the temperature control ring 6 position above 300mm of' the 30 ° C. from the supply pipe 18 ^'with blown ^{respectively'''} a more 0.99 ° C. in air 2 liters of warm water
After contacting the second mandrel 7 which is circulated at a speed of / min, the nip rolls 10 and 10 move the speed to 2 m / min.
And a tube having a wall thickness of 150 μ was obtained.

An aluminum tube having an outer diameter of φ140 was inserted into the obtained tube, left for 1 hour in an oven whose temperature was controlled at 150 ° C., and then taken out of the oven for natural cooling. As a result, an endless belt-coated drum fitted to an aluminum tube was created.

The endless belt portion of the obtained coated drum was cut open and the diameter in the longitudinal direction was measured.
It was 0.5 mm, and the change in wall thickness in the circumferential direction was ± 5%. Also, using RA8340A manufactured by Advantest, JI
According to SK-6911, the volume resistance was measured using a sample having a thickness of 150 μm. However, the electrode is made of conductive silicone rubber, and the force for pressing the electrode against the sample is 4 kg. As a result, the volume resistance in the longitudinal direction and the circumferential direction is 1 × 10 ^{13 to} 9
It was in the range of × 10 ¹³ Ω · cm and was sufficiently satisfactory as an endless belt-coated drum for an electrophotographic copying machine.

[0040]

EFFECTS OF THE INVENTION According to the present invention, it is possible to manufacture an endless belt which is provided with heat shrinkability and which has uniform resistance and no creases, and is cut into a desired length in a ring shape. Then, after the drum is inserted into the tube, it is subjected to heat treatment, and can be suitably used as a transfer drum for an electrophotographic copying machine.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an apparatus applied to a method for producing a thermoplastic endless belt material having heat shrinkability according to the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is an explanatory diagram showing a relationship between an annular die, first and second mandrels, and a tube.

[Explanation of symbols]

 1 Tube Manufacturing Equipment 2 Extruder 3 Annular Die 4 Support Tube 5 First Mandrel 6,6 ', 6' ', 6' '', 6 '' '' Temperature Control Ring 7 Second Mandrel 8 Inner Roll 9 Outer Roll 10 Nip Roll 11 Supply Pressure / Supply Flow Control Gas Continuous Supply Mechanism 12, 12 'Mandrel Heat Medium Supply Mechanism 13 Blowout Port 14 Supply Pipe 15 Blowout Port 16 Discharge Pipe 17, 17' Inlet Port 18, 18 'Supply Pipe 19, 19 'Outlet 20,20' Discharge pipe

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Chiharu Kongou 1st Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd. Yokkaichi Research Institute

Claims (1)

[Claims] 1. A thermoplastic resin composition is melted and extruded in a tube shape downward from an annular die attached to an extruder, and a temperature-controlled gas is blown onto the outer peripheral surface of the tube, and a supply pressure is applied to the inside of the tube. And the gas whose supply flow rate is controlled are continuously supplied / excluded, and then the temperature-controlled first mandrel is contacted, and the temperature-controlled gas is applied to the outer peripheral surface of the tube in the vicinity where the contact of the first mandrel is started. The second mandrel, whose outer diameter is larger than that of the first mandrel and whose temperature is controlled, is provided below the first mandrel, and the temperature controlled gas is sprayed on the outer peripheral surface of the tube between the first mandrel and the second mandrel. A method for producing an endless belt material having heat shrinkability, which is characterized in that it is continuously taken in a tubular shape and cut into a sliced shape.