JPH04255332A - Manufacture of resistance control endless belt material - Google Patents

Abstract

PURPOSE:To prepare a resistance control endless belt with a uniform diameter and thickness and a uniform surface resistance level. CONSTITUTION:A thermoplastic resin compsn. compounded with an electrically conductive filler is melted and is extruded downward into a tube-like shape from a ring die 3 mounted on an extruder 2. A temp.-controlled gas is blown on the outer peripheral face of this tube and a gas both feeding pressure and flow quantity of which are controlled is continuously fed and discharged inside of the tube. Then, the tube is brought into contact with a temp.-controlled mandrel 5 and temp.-controlled gas is blown again to the outer peripheral face of the tube at a point being adjoining to the position of contact. Then, while the tube-like shape is kept, the tube is continuously taken up by means of nip rolls and it is cut into round slices to obtain a resistance control endless belt material.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a resistance-controlled endless belt material used in electrophotographic copying machines, photoreceptor devices such as laser printers, intermediate transfer devices, transfer separation devices, charging devices, etc. The present invention relates to a manufacturing method.

0002

2. Description of the Related Art Conventionally, endless belts having seams have been frequently used in electrophotographic copying machines, photoreceptor devices such as laser printers, intermediate transfer devices, transfer separation devices, charging devices, and the like.

When driving an endless belt having such a seam, there is a problem in that minute vibrations occur at the seam, making it impossible to increase the speed. Furthermore, when used as a resistance-controlled endless belt in a photoreceptor device, intermediate transfer device, etc., the photosensitive performance and transfer performance at the seam are significantly different from other parts, and there is a problem that the belt cannot be used functionally. .

[0004] Various manufacturing methods for obtaining endless belts without seams have been proposed, but the current situation is that a satisfactory manufacturing method has not yet been obtained.

As a method for manufacturing such an endless belt, the present inventors proposed a method for manufacturing an endless belt material made of polycarbonate in Japanese Unexamined Patent Publication No. 1-228823.

[0006]

[Problem to be solved by the invention] JP-A-1-22882
In the method proposed in Publication No. 3, in which gas is blown from a temperature control ring near the annular die and then cooled from inside using only a mandrel, it has been found that the surface resistance of the obtained endless belt varies by more than ±2 to 3 orders of magnitude. did. When an endless belt with such a resistance control level is used in an electrophotographic copying machine or the like, there is a problem in that image unevenness occurs and clear images cannot be obtained.

The present invention has been made in view of these problems, and its purpose is to provide a manufacturing method for obtaining an endless belt material that is perfectly circular, has a uniform wall thickness, and has a uniform surface resistance level. It provides:

[0008]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the inventors of the present invention found that the reason why the resistance level of the endless belt surface is uneven is due to the molten state extruded from the annular die. It has been found that this is because the tube is cooled unevenly while passing through the mandrel. Furthermore, the surface resistance level of the endless belt can be controlled within ±1 order by blowing gas again from the outer peripheral surface of the tube near the upper end of the mandrel where the tube deforms the most to bring the temperature of the outer peripheral surface closer to the mandrel temperature. They discovered this.

That is, the method for manufacturing an endless belt material of the present invention involves melting a thermoplastic resin composition containing a conductive filler and extruding it into a tube shape downward through an annular die attached to an extruder. At the same time as blowing temperature-controlled gas onto the outer circumferential surface of the tube, gas with controlled supply pressure and flow rate is continuously supplied and removed from the inside of the tube.
Next, while bringing it into contact with a temperature-controlled mandrel,
The temperature-controlled gas is again blown onto the outer peripheral surface of the tube near where it starts contacting the mandrel, and then the tube is continuously pulled out and cut into slices while maintaining its tube shape. This is a method for manufacturing a resistance-controlled endless belt material.

0010

[Example] The resin composition applied in the present invention is basically a thermoplastic resin mixed with a conductive filler.

Examples of thermoplastic resins include polycarbonate, polyethylene terephthalate, polyether ether ketone, polyfukkavinylidene, polyamide, acrylic, polyolefin, polysulfone, polyether sulfone, ethylenetetrafluoroethylene copolymer, acrylic copolymer, and polyester. It is preferable to use at least one selected from copolymers, polyetherester copolymers, polyetheramide copolymers, olefin copolymers, and polyurethane copolymers, or a mixture of several of these.

The conductive filler is at least one selected from carbon black, graphite, carbon fiber, metal powder, conductive metal oxide, organometallic compound, organometallic salt, conductive polymer, etc., or several of these. Those consisting of a mixture are preferred. Among them, carbon black is particularly preferred. Carbon blacks include carbon blacks such as acetylene black, furnace black, and channel black. S. with a large specific surface area.
C. F. (Super Conductive Fur
nace), E. C. F. (Electric Co.
It is advantageous to use Ketjen Black EC (trade name, manufactured by AKZO), as it is possible to obtain the desired conductivity with a small amount of blending ratio.

The amount of carbon black blended is 3 to 25 parts by weight per 100 parts by weight of the thermoplastic resin. If the carbon black is less than the above range, the conductivity will be poor, and if it is more than the above range, the appearance of the product will be poor and the material strength will be reduced, which is not preferable.

[0014] The resin composition may contain various additional components that are commonly incorporated into resin compositions, as long as they do not impede the object of the present invention. Such components include antioxidants, lubricants, mold release agents, and the like.

The endless belt material manufacturing apparatus 1 is shown in FIG.
As shown in FIGS. 2 and 3, the upper part of the support tube rod 4 was fixed coaxially to the annular die 3 attached to the extruder 2, and the mandrel 5 was coaxially fixed to the lower part of the support tube rod 4. It is something.

Temperature control rings 6, 6', 6'' are arranged coaxially with the support tube rod 4 between the annular die 3 and the mandrel 5, and a plurality of sets of nip rolls 9 are arranged below the mandrel. The nip roll 9 includes a plurality of inner rolls 7, 7 disposed on the outer periphery of the support pipe rod 4 below the mandrel 5, and an outer roll 8 disposed corresponding to these inner rolls 7, 7. ,8
It consists of.

The support tube rod 4 is provided with a gas continuous supply mechanism 10 for controlling supply pressure and supply flow rate and a mandrel heating medium supply mechanism 11.

The supply pressure/supply flow rate control gas continuous supply mechanism 10 includes a supply pipe 13 that passes through the support tube rod 4 and opens to the blowout port 12, and a supply tube 13 that passes through the support tube rod 4 and opens to the blowout port 14.
It consists of a discharge pipe 15 that opens to.

The in-mandrel heating medium supply mechanism 11 includes a supply pipe 17 passing through the support tube rod 4 and opening to an inlet 16 in the mandrel 5, and a supply tube 17 passing through the support tube rod 4 and opening into the inlet 16 in the mandrel 5. It consists of a discharge pipe 19 that opens to the outlet 18.

[0020] The annular die 3 must be installed facing downwards, since if it faces upwards with respect to the extruder 2, the tube will deform due to its own weight and creases will occur.

The structure of the annular die 3 is not limited in any way, but a spiral die is preferable from the viewpoint of uniformity of the wall thickness of the tube. Further, the die may be a single layer die or a multilayer die, and in the case of a multilayer die, the resin compositions of each layer may be the same or different.

Although the mandrel 5 is spaced apart below the annular die 3, it may be connected below the annular die 3 or may pass through the annular die 3 and be connected to an external structure. .

The distance between the die lip of the annular die 3 and the position where the molten tube first contacts the 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 will deform rapidly between the die lip and the mandrel 5, making it easy to cut and making continuous production difficult. On the other hand, if the length is 500 mm or more, the molten tube with low melt tension will occupy a large proportion of the tube between the die lip and the mandrel 5, making the tube shape unstable and making stable continuous production difficult.

As shown in FIG. 3, the relationship between the diameter D1 of the die lip of the annular die 3 and the diameter D2 of the mandrel 5 is preferably D2 = 3D1 or less and D2 = 0.5D1 or more, preferably D2 = 1.5D1 or less, D2 = 0.6D1 or more, more preferably D2 = 0.99D1 or less, D2 = 0.8D1
That's all. If the diameter D2 of the mandrel 5 is 3D1 or more, stick-slip sag occurs at the position where the molten tube contacts the mandrel 5, making it impossible to obtain a tube with a uniform wall thickness in the longitudinal direction. On the other hand, D
If 2 is less than 0.5D1, the molten tube will not contact the mandrel 5 at the same time in the circumferential direction, making it impossible to obtain a tube with a uniform wall thickness.

Most preferably, as shown in FIG.
The diameter D2 of the mandrel 5 is determined by the diameter D1 of the die lip.
It is preferable to make the temperature slightly smaller and bring the tube into complete contact with the mandrel 5 for solidification at controlled temperature.

The peripheral edge of the mandrel 5 on the annular die 3 side is 2
It is preferable to chamfer with a radius of mmR or more and 20 mm or less.

The length of the mandrel 5 in the longitudinal direction is preferably 10 mm or more, but preferably 20 mm or more and 3 times or less the diameter D1 of the die lip. If it is less than 10 mm, pressure control within the space surrounded by the die lip, mandrel 5, and molten tube will become unstable. When the diameter D1 of the die lip is three times or more, the frictional force between the solidified tube and the side surface of the mandrel 5 increases, and the solidified tube is plastically deformed between the mandrel 5 and the nip roll 9 located next, causing the wall of the tube to deteriorate. The thickness becomes uneven.

[0028] The surface condition of the mandrel 5 is desirably treated with a so-called satin finish having an unevenness of 0.3μ or more, preferably 0.5μ or more and 25μ or less, and more preferably 1μ or more and 10μ or less. good. If the unevenness is less than 0.3μ, stick-slip will occur at the position where the molten tube contacts the mandrel 5, making it impossible to obtain a tube with a uniform wall thickness in the longitudinal direction.If the unevenness is 25μ or more, the tube will Scratches occur on the inner surface, and pressure control within the space surrounded by the die lip, mandrel 5, and molten tube becomes unstable.

The material of the mandrel 5 is preferably metal, ceramics, wood, cloth, etc., and preferably metal or ceramics. Plastic materials such as Teflon are not preferred because they tend to cause stick-slip.

The mandrel 5 may be a perfect circle with a constant diameter in the longitudinal direction, or may have a reverse tapered shape with a larger diameter on the side closer to the die lip and a slope of 5/100 or less. .

The surface temperature of the mandrel 5 is the glass transition point (
It is desirable that the temperature be below Tg) or below the melting point (Tm), preferably below Tg-10°C or below Tm-10
below ℃. When the temperature exceeds Tg or Tm, stick-slip occurs on the mandrel 5, making it impossible to obtain a tube with a uniform wall thickness in the longitudinal direction.

Although known means can be used to adjust the surface temperature of the mandrel 5, from the viewpoint of temperature control accuracy and temperature control ability,
It is desirable to circulate a temperature-controlled heating medium inside the mandrel 5.

[0033] It is necessary to continuously supply and discharge gas with controlled supply pressure and supply amount to the space surrounded by the die lip, mandrel 5, and molten tube, and the space is kept in a sealed state. This may cause slight unevenness in the drawing that does not affect the uniformity of the wall thickness of the tube, or the tube in a molten state between the die lip and the mandrel 5 may not be in contact with each other in the circumferential direction at the same time. A tube with uniform wall thickness cannot be obtained.

The gas to be continuously supplied is preferably air or nitrogen, and the temperature of the gas to be supplied is preferably constant.

As shown in FIGS. 1 and 3, near the position where the molten tube contacts the mandrel 5,
Regarding the cross section cut along the vertical plane passing through the center of the annular die 3 and the center of the mandrel 5, the point where the molten tube touches the mandrel 5 is defined as point A, and the point on the tube immediately above point A is defined as point B. , a point on a line passing through point A and parallel to a line passing through the center of the annular die 3 and the center of the mandrel 5 is defined as point C.

Regarding the left side when facing the mandrel 5, ∠CAB formed by the line AC connecting points A and C and the line AB connecting points A and B, clockwise is - and counterclockwise is +. When ∠CAB is preferably +20° or less and −45° or more,
The angle is preferably +10° or less and −30° or more, more preferably 0° or less and −20° or more. ∠CAB is +2
If the temperature exceeds 0°, the molten tube will move to the mandrel 5.
This prevents simultaneous contact in the circumferential direction, making it impossible to obtain a tube with uniform wall thickness. On the other hand, when ∠CAB is less than -45°, stick-slip occurs on the mandrel 5, making it impossible to obtain a tube with uniform wall thickness.

[0037] As a means for continuously taking off the solidified tube without creating creases, a nip roll is employed. Inside the continuously moving tube, inner rolls 7 are attached at at least two places around the support tube rod, and corresponding to these inner rolls 7, outer rolls 8 covered with a rubber elastic material are provided on the outside of the tube. and. By sandwiching the tube between an inner roll 7 and an outer roll 8, the tube is continuously taken up. .

The driving force for taking up the tube is provided by the outer roll 8.
It is preferable to apply it to the side from the viewpoint of simplicity and operability of the device.

If the tube taken up by the nip rolls 9 is allowed to be slightly deformed, it can be wound up while retaining the gas inside the tube, and if even a slight deformation is not allowed, the tube can be taken up by the nip rolls. What is necessary is just to cut the tube taken out from 9 into round slices to a desired length.

The wall thickness of the tube obtained according to the present invention is 10μ.
The thickness is preferably 20μ or more and 2000μ or less, preferably 20μ or more and 1000μ or less. If the wall thickness of the tube is less than 10 μm, plastic deformation occurs when the tube is taken off by the nip rolls 9, making it impossible to obtain a tube with a uniform wall thickness. When the thickness exceeds 2000μ, cooling on the mandrel 5 becomes difficult.

In this way, the outer peripheral surface of the molten tube extruded from the annular die 3 attached to the extruder 2 is heated by the temperature control ring 6.
, 6′, 6″ to control the temperature,
While continuously supplying gas with controlled supply pressure and supply flow rate from the supply pipe 13 to always keep the internal pressure at a predetermined pressure,
The inside of the tube is brought into contact with a mandrel 5 to solidify at a controlled temperature, and then passed between nip rolls 9 arranged at predetermined intervals in the circumferential direction of the support tube rod 4 and taken off while maintaining the tube shape. Even when cut into rounds, there are no seams or creases.

[0042] The obtained tube is preferably heat-treated under tension in order to improve its thermal and temporal dimensional stability and to correct minute plastic deformations.

Next, specific embodiments of the present invention will be explained.

(Example 1) Outer diameter of die lip: 140 mm
A support tube rod 4 with an outer diameter of 135 mmφ is inserted through the annular die 3, which is a four-row annular spiral die with a lip gap of 1 mm.
, the length of the side surface is 50mm, and the circumference on the annular die 3 side is 5mmR.
A steel mandrel 5, which has been chamfered with 100 mm and is sprayed with alumina ceramics so that the surface unevenness is 2 μm, is attached at a position 100 mm from the end face of the annular die 3. Furthermore, rubber inner rolls 7, 7 with a diameter of 10 mm are attached to a position 100 mm below the lower end of the mandrel 5, and a motor ( (not shown)
mmφ rubber outer rolls 8, 8 are provided, and an inner roll 7 is provided.
and the outer roll 8 constitute nip rolls 9, 9.

[0045] Melt flow rate (MFR) is 4.6g
/10 minutes (280°C) polycarbonate (Iupilon E-2000 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 83 parts by weight, MF
Polybutylene terephthalate with R of 4.32 g/10 min (230°C) (Novadol 5020 manufactured by Mitsubishi Kasei Corporation)
17 parts by weight and 16 parts by weight of acetylene black (manufactured by Denki Kagaku Co., Ltd.) with a specific surface area of 70 m2/g were kneaded and granulated using a vented twin-screw extruder, and the resulting pellets were
Extruded from a 50 mmφ extruder at a temperature of 280°C, air at 150°C was passed through a temperature control ring 6 near the annular die 3,
Air at a temperature of 80°C is supplied from the temperature control ring 6' located 20 mm above the top of the mandrel.
Air at 80°C is blown from the temperature control ring 6'' at the 0mm position, and 0.03kg is supplied from the supply pipe 13.
/cm2, INL/min of air, ∠CAB
The tube in a molten state with -5° is brought into contact with the mandrel 5 in which hot water of 85°C is circulated at 2 L/min from the supply pipe 17, and then 2
A tube with a wall thickness of 150 μm was obtained by drawing at a speed of m/min.

The diameter change in the longitudinal direction of the obtained tube was ±0.5 mm, and the wall thickness change in the circumferential direction was ±5%. In addition, using a surface resistance meter Hiresta HA probe (manufactured by Mitsubishi Yuka Co., Ltd.), the measurement voltage was 100V, and the measurement time was 10.
When evaluated in seconds, the surface resistance in the longitudinal and circumferential directions was in the range of 3 x 108 to 8 x 108 Ω/mouth, which was sufficiently satisfactory as a resistance control endless belt for electrophotographic copying machines. .

[0047]

[Effect of the invention] According to the present invention, the diameter and wall thickness are uniform;
In addition, a resistance-controlled endless belt material with uniform surface resistance and no creases can be produced, which can be cut into slices of a desired length and suitably used as a resistance-controlled endless belt for electrophotographic copying machines.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an apparatus applied to the method of manufacturing a resistance-controlled endless belt material of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is an explanatory diagram showing the relationship between an annular die, a mandrel, and a tube.

[Explanation of symbols]

1 Resistance control endless belt material manufacturing device 2 Extruder 3 Annular die 4 Support pipe rod 5 Mandrel 6, 6', 6'' Temperature control ring 7 Inner roll 8 Outer roll 9 Nip roll 10 Supply pressure/supply flow rate control gas continuous supply mechanism 11
Heat medium supply mechanism in mandrel

Claims (1)

[Claims] Claim 1: A thermoplastic resin composition containing a conductive filler is melted and extruded into a tube shape downward through an annular die attached to an extruder, and a temperature-controlled gas is blown onto the outer circumferential surface of the tube. Gas with controlled supply pressure and supply flow rate was continuously supplied and expelled to the inside of the tube, and then it was brought into contact with a temperature-controlled mandrel, and the temperature was again controlled on the outer peripheral surface of the tube near where it started contacting the mandrel. 1. A method for producing a resistance-controlled endless belt material, which comprises blowing a gas, and then continuously pulling the material while maintaining the tube shape to cut it into circular slices.