JPH01228823A - Manufacture of tubular polycarbonate film and device therefor - Google Patents

Abstract

PURPOSE:To obtain a belt which has a uniform diameter and thickness and is free from a seam and fold by a method wherein a tubular film extruded through an annular die is brought into contact with a cooling mandrel while gas, whose feed pressure and feed quantity are controlled, is being fed/discharged continuously from the inside of the tubular film and the tubular film is always received maintaining a tubular state. CONSTITUTION:An outer circumference of a molten film (a) of polycarbonate extruded into a tubular state through an annular die 3 fitted to an extruding machine 2 is cooled with cool air blown off through a cooling ring 6. Then gas (b) whose feed pressure/feed quantity are controlled is fed on the inside of the film (a) continuously through a feed pipe 13, discharged through a discharge pipe 15 and solidified through cooling by bringing the film (a) into contact with a cooling mandrel 5 with the inner pressure fixed. Then the same is passed through among nip rolls 9, 9, 9, 9 arranged on the circumference of a supporting pipe bar 4 and in a state at intervals of 90 deg. in a circumferential direction and received while maintaining the tubular state. Therefore, the received tubular polycarbonate film F is free from a seam and fold even if the same is cut into round slices.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for producing a tubular polycarbonate film suitable as a material for electronic devices.

(Prior art) Polycarbonate films are used as electrical insulating parts or materials for electrical equipment by taking advantage of their mechanical properties such as high impact strength and tensile modulus, as well as excellent electrical properties and heat resistance. Used in various devices.

In particular, taking advantage of the above characteristics, it is used as drive belts for various devices, photosensitive belts for electrophotography, and the like. In this case, when the belt is shaped like a ring, the uniformity of the diameter in the width direction and the uniformity of the thickness in the width direction of the belt are particularly important. A shaped film is cut to a predetermined length, and both ends are spliced to form a belt (a).Therefore, although the diameter of the belt in the width direction is approximately equal, there is a seam (b).

When such a seam (B) is used as a drive belt, minute vibrations occur at the seam (B), which limits its application to precision equipment. In this case, the photosensitive performance of the seam (b) portion is different from that of other portions, so the seam (b) portion cannot be used functionally, resulting in a problem that the performance as a photosensitive belt for electrophotographic equipment is degraded.

Therefore, in order to make a seamless belt, as shown in Figure 5, polycarbonate resin is extruded in a tube shape from an annular die (c), cooled and solidified to form a tubular film (d). A method has been proposed in which the material is cut into rings and made into belts.

However, the diameter of the tubular film, which corresponds to the uniformity of the diameter in the width direction of the belt made in this way, changes from the molten state to the solidified state between the annular die (c) and the take-up nip roll (e). The process of passing from the annular die to the nip rolls is carried out by a sealed pressurized gas and a cooling ring near the annular die (c) or cooling gas blown around the tubular film. The diameter of the tubular film is determined by the balance between the increasing melt tension of the tubular film in the molten state and the thickness of the tubular film that gradually becomes thinner from the annular die to the nip roll, making the diameter of the tubular film uniform. The problem is that it is difficult.

Moreover, in order to seal the pressurized gas inside the tubular film, it is essential to use a take-up nip roll.
When a nip roll is used, the tubular film is folded in two, and the folded part undergoes deformation exceeding the yield point elongation, forming two folds parallel to the longitudinal direction of the tubular film. The performance of the photosensitive belt is different from that of the pond part, and the performance of the photosensitive belt is lowered.

As described above, it is impossible to obtain a belt that has a uniform diameter when the belt is formed into a ring shape, a uniform thickness in the width direction, and has no seams or creases.

(Problems to be Solved by the Invention) Conventionally, a bell l~ has uniformity in diameter in the width direction,
Another problem is that it is impossible to produce a tubular polycarbonate film that has a uniform thickness in the width direction and has no seams or creases.

(Means for Solving the Problems) The present invention provides a tubular polycarbonate film that has a uniform diameter in the width direction of the belt, a uniform thickness in the width direction, and has no seams or creases. Accordingly, claim (1) is a method of continuously supplying and discharging gas with controlled supply pressure and supply amount to the inside of a tubular polycarbonate film extruded from an annular die attached to an extruder, and then to a cooling mandrel. A method for producing a tubular polycarbonate film, characterized in that the tubular polycarbonate film is brought into contact, cooled and solidified, and is continuously taken off while maintaining the tube state, and claim (2) is characterized in that the polycarbonate film is made of a polycarbonate film that is identical to the annular die attached to the extruder. a support tube rod is fixed axially, a cooling mandrel is fixed concentrically to the support tube rod, and a cooling ring is disposed concentrically with the support tube rod between the annular die and the cooling mandrel; A plurality of nip rolls each consisting of a plurality of inner rolls pivotally supported on the outer periphery of the support tube rod below the cooling mandrel and outer rolls provided correspondingly to these inner rolls are disposed, and the nip rolls are provided on the support tube rod. This is a tubular polycarbonate film manufacturing apparatus characterized by being equipped with a gas continuous supply mechanism for controlling supply pressure and supply amount, and a heating medium supply mechanism within a cooling mandrel.

(Example) As shown in FIGS. 1, 2, and 3, the tubular polycarbonate film manufacturing apparatus 1 includes a support tube 4 coaxially attached to an annular die 3 attached to an extruder 2. A cooling mandrel 5 is fixed concentrically to this supporting tube body 4.

Next, a cooling ring 6 is disposed concentrically with the support tube 4 between the annular die 3 and the cooling mandrel 5, and is pivoted on the outer periphery of the support tube 4 below the cooling mandrel 5. Inner rolls 7.7°7... are provided, and outer rolls 8, 8 are provided corresponding to these inner rolls 7.7.7..., respectively.
．． 8, and a plurality of sets of nip rolls 9, 9, 9, . . . each consisting of an inner roll 7 and an outer roll 8 are provided.

The support pipe body 4 is equipped with a supply pressure/supply amount control gas continuous supply/discharge mechanism 10, and a heating medium is supplied into the cooling mandrel 5.
Circulating cooling mandrel heat medium supply machine horizontal 11
It is attached.

The supply pressure/supply amount control gas continuous supply/discharge mechanism 10 includes a supply pipe 13 that passes through the support tube 4 and connects to the blowout port 12, and a discharge pipe that passes through the support tube 4 and connects to the blowout port 14. 15.

A heat medium supply mechanism 11 into the cooling mandrel 5 includes a supply pipe 17 that passes through the support pipe 4 and is connected to an inlet 16 that opens into the cooling mandrel 5, and a supply pipe 17 that passes through the support pipe 4 and connects to the inflow port 16 that opens into the cooling mandrel 5. It consists of a discharge pipe 19 connected to an outlet 18 in the mandrel 5.

A tubular polycarbonate film is manufactured using such a tubular polycarbonate film manufacturing apparatus as follows.

That is, a molten film (a> is extruded into a tube shape from an annular die 3 attached to an extruder 2) and a cooling ring 6 is attached to the outer periphery.
Gas (b) is cooled by the cold air blown out from the inside, and the supply pressure and supply amount are controlled through the supply pipe 13.
is continuously supplied and discharged through the discharge pipe 15, is brought into contact with the cooling mandrel 5 to be cooled and solidified while always keeping the inner pressure at a predetermined pressure, and then is cooled and solidified around the support tube 4 in the circumferential direction at 90 degree intervals. Nip rolls 9, 9, 9 arranged in a shape
．． Pass it through the tube between 9 and take it out while maintaining the tube shape.

Therefore, even when the tubular polycarbonate film (F) is cut into slices, there are no seams or creases.

The polycarbonate resin used in the present invention is not particularly limited, and typical examples include polycarbonate made of bisphenol A and polycarbonate copolymer of bisphenol A and halogenated bisphenol A.

In addition, JISK of the polycarbonate resin used in the present invention
MFR by 6719 is 0.05g/10min or more20
g/10 minutes or less, preferably 0.1 g/10
min or more and Log/10 min or less, and when the MFR is less than 0905, the molten tubular polycarbonate loses its ductility and uniform deformation becomes difficult, so it tends to be difficult to obtain a tubular polycarbonate film with a uniform thickness.

On the other hand, if the MFR exceeds 20 g/10 minutes, the melt tension of the tubular polycarbonate film in the molten state becomes small, and as a result, the tube shape becomes unstable during the process of solidifying from the molten state, making it difficult to maintain uniform diameter and thickness. Tubular polycarbonate films tend to be difficult to obtain.

The annular die in the present invention may be installed upward or downward relative to the extruder, but if the film production speed is relatively slow, if it is placed upward, it may deform due to the film's own weight, resulting in creases, etc. , so downward direction is preferable.

The structure of the annular die is not limited to the same, but a spiral die is preferable from the viewpoint of uniformity of the thickness of the tubular film, and the annular die may be a single layer die or a multilayer die, In this case, the polycarbonate resins in each layer may be the same or different.

Although the cooling mandrel in the present invention is positioned next to the annular die, the cooling mandrel may be connected to the annular die or may pass through the annular die and be connected to an external structure.

It is preferable that the temperature environment around the molten tubular film between the annular die and the cooling mandrel is in a stable state, and a temperature-controlled gas is uniformly blown from the cooling ring from the outside of the tubular film. is preferred.

The distance between the die lip of the annular die and the point where the molten tubular film first contacts the cooling mandrel is 20
It is preferable that the diameter is 500111+ or less, and if it is not grooved to 20 nua, the tubular molten film will be rapidly deformed between the die lip and the cooling mandrel, making it easy to cut and making continuous production difficult. On the other hand, when the temperature exceeds 500, the tube shape becomes unstable because the proportion of the molten tubular film with low melt tension increases among the tubular film in the molten state between the die lip of the annular die and the cooling mandrel. This makes stable continuous production difficult.

Referring to FIG. 3, the relationship between the die lip diameter D1 of the annular die and the diameter D2 of the cooling mandrel is such that D = 3D or less, D2 = 0.5D or more, and preferably D2 = 1.5D or more. 5D or less,
D2=0.6D1 or more, more preferably D
= 0.99D1 or less, p2 = 0.8D1 or more. If the diameter D of the cooling mandrel exceeds 3D1, stick-slip sag occurs at the position where the molten tubular film contacts the cooling mandrel, making it impossible to obtain a film with a uniform thickness in the longitudinal direction.

On the other hand, if D is less than 0.5D, the molten tubular film will not simultaneously contact the cooling mandrel in the circumferential direction, making it impossible to obtain a film with uniform thickness.

゛The most desirable form, as shown in Fig. 3, is to make the diameter D2 of the cooling mandrel smaller than the diameter D1 of the die lip, and to make the diameter D of the molten tubular film between the die lip and the cooling mandrel smaller than the diameter D1 of the cooling mandrel. The tubular molten film may be cooled and solidified by contacting the cooling mandrel with a diameter smaller than D2.

It is preferable to chamfer the peripheral edge of the cooling mandrel on the annular die side with a radius of 2111IR or more and 20mmR or less.

The length of the cooling mandrel in the longitudinal direction is preferably 10 m.
+ or more, but preferably 20 nu+ or more and 3 times the die lip diameter or less, and if it is less than 10 nu, control of the internal pressure in the space surrounded by the die lip, cooling mandrel, and molten tubular film becomes unstable. . Die lip diameter 3
If the temperature exceeds twice that, the palm rubbing between the cooled and solidified tubular film and the side surface of the cooling mandrel will increase, and the cooled and solidified film will be plastically deformed between the cooling mandrel and the nip roll located next to the cooling mandrel. The thickness of the tubular film becomes uneven.

The surface condition of the cooling mandrel is desirably 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.
It is better to set the roughness to 10 to 1 or less.A molten tubular film with an unevenness of less than 0.3μ will cause stick-slip at the position where it contacts the cooling mandrel, making it impossible to obtain a film with a uniform thickness in the longitudinal direction, and the unevenness will occur. If it exceeds 25μ, scratches will appear on the inner surface of the tubular film, and control of the internal pressure in the space surrounded by the die lip, cooling mandrel, and molten tubular film will become unstable.

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

The cooling mandrel is a perfect circle with a constant diameter in the longitudinal direction, or a 5/1 cooling mandrel with a larger diameter on the side closer to the die lip.
It may also have a reverse tapered shape with a slope of 00 or less.

The temperature of the surface of the cooling mandrel is preferably 0°C or more and 200°C or less, preferably 10°C or more and 150°C or less, and more preferably 20°C or more and 130°C or less. When the temperature is below 0℃, the molten tubular film rapidly cools and solidifies the moment it comes into contact with the cooling mandrel, so the molten tubular film does not come into contact with the cooling mandrel stably and continuously, resulting in a uniform thickness. It is no longer possible to obtain a film that is accurate. If the temperature exceeds 200°C, stick-slip occurs on the cooling mandrel, making it impossible to obtain a film with a uniform thickness in the longitudinal direction.

Although known means can be used to adjust the temperature of the cooling mandrel, it is desirable to circulate a temperature-controlled heating medium inside the cooling mandrel in terms of temperature control accuracy and temperature control ability.

The space surrounded by the die lip, the cooling mandrel, and the molten tubular film needs to be continuously supplied with gas with a controlled supply site and supply pressure, and must be continuously discharged. If the die lip and cooling mandrel are in a closed state, there will be slight unevenness in the film take-up that does not affect the uniformity of the film thickness, or the tube in the molten state between the die lip and the cooling mandrel may come into contact uniformly and simultaneously. This makes it impossible to obtain a film with uniform thickness.

As the gas to be continuously supplied, air and nitrogen are preferable.
Further, it is preferable that the temperature of the gas to be supplied is constant.

With reference to FIGS. 1 and 3, in the vicinity where the molten tubular film contacts the cooling mandrel, the molten tubular film is The point where the shaped film touches the cooling mandrel is point A, the point on the tubular film immediately above point A is point B, and a line parallel to the line passing through point A and the center of the annular die and the center of the cooling mandrel is defined as point A. The point on the line is the 0 point, and when the cooling mandrel is located below the annular die, point A and 0 are respectively related to the left side facing the cooling mandrel and above the annular die to the right side facing the cooling mandrel. line AC connecting the points
When jcAB formed by and a line AB connecting points A and B, the clockwise direction is - and the counterclockwise direction is 1.1. ? CAB is +
20° or less -45° or more is desirable, preferably +10
-30° or more, more preferably ±0° or less -2
It is preferable to set it to 0° or more. If ZCAB exceeds 120°, the molten tubular film will not come into uniform contact with the cooling mandrel at the same time, making it impossible to obtain a film with uniform thickness. On the other hand, if 5,1cAB is less than 145°, stick-slip occurs on the cooling mandrel, making it impossible to obtain a film of uniform thickness.

The means for continuously taking off the cooled and solidified tubular polycarbonate film without creating creases includes at least two means located inside the continuously moving tubular film and around the support tube on the opposite side of the annular die. At least two rotatable or non-rotatable inner rolls are attached, and between these nip rolls and corresponding outer rolls located outside the tubular film and covered with a rubber elastic material, This is possible by sandwiching a tubular film.

The driving force for taking up the tubular film is preferably applied to the outer roll side in view of the complexity of the device and ease of operation.

The tubular film drawn by the nip roll can be rolled up with the amount of deformation within the allowable range for the intended use, while retaining gas within the tubular film, and in cases where even the slightest deformation is unacceptable. The tubular film taken from the nip rolls may be cut into slices of desired length.

The thickness of the tubular polycarbonate film obtained by the present invention is desirably 10μ or more and 1000μ or less, preferably 15μ or more and 500μ or less, and more preferably 2
It is 0 μ or more and 300 μ or less. Film thickness is 10μ
If it is less than 1,000 μm, it will be plastically deformed when taken off with nip rolls, making it impossible to obtain a film with a uniform thickness, and if it exceeds 1,000 μm, cooling on a cooling mandrel will be difficult.

The obtained tubular polycarbonate film was kept under tension at a temperature of 200°C or less in order to provide thermal dimensional stability over time and to correct small plastic deformations within an allowable range. Heat treatment is recommended.

An example of implementing the present invention will be described with reference to FIGS. 1, 2, and 3.

The support tube 4 that passes through the annular die 3 is made of a four-ring spiral die with a die lip outer diameter of 75 mm and a lip gap of 0°5. A steel cooling mandrel 5 whose periphery has been chamfered with 5 rava R and alumina-based ceramics sprayed so as to have a surface unevenness of 2 μm is installed at a position of 60 cm from the end face of the annular die 3, and further 10 cm below the lower end of the cooling mandrel 5.
A rubber inner roll 7.7 with a diameter of 10 mm is installed at the 0 mm position, and these two inner rolls 7.7 are respectively located outside the tubular film and driven by a motor (not shown). A rubber outer roll 8.8 with a diameter of 50 stops is provided, nip rolls 9, 9 consisting of an inner roll 7 and an outer roll 8 facing each other are provided, and polycarbonate resin (Mitsubishi Gas Chemical, Kneepilon E-2000
, MFR=5g/10min) from a 50-stop φ extruder.
While extruding at 0°C and blowing air at 100°C from the cooling ring 6, 0.03 kg/aa, IN from the supply pipe 13.
Q/nin air is supplied, and the molten tubular film with ZCAB set to -5° is heated to 80°C from the supply pipe 13.
The hot water was circulated at 2 Q/nin and brought into contact with the cooling mandrel 5, and then taken off at 5 m/1 ain by nip rolls 9.9 to obtain a tubular polycarbonate film with a film thickness of 100 μm.

The obtained film had a change in diameter of ±0.5%, a change in thickness in the circumferential direction of ±5%, no change in thickness due to stick-slip in the longitudinal direction, and conformed to JISK711.
3, the tensile modulus is 22,000 kt/aA in the circumferential direction and 23,000 in the longitudinal direction.
ksr/-, heat shrinkage rate at 140°C is 0%
It was a tubular polycarbonate film with excellent mechanical and thermal properties, uniform diameter and thickness, and no creases.

(Effects of the Invention) Since the present invention can produce a fold-free tubular polycarbonate film with a uniform diameter and thickness,
When cut to the required length and sliced into ring shapes, it can be used as a flashing belt for electronic equipment to perform various functions over the entire length and width, and because there are no seams or creases, it is also suitable as a drive belt. It can be used as a material for many purposes.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts of the device of the present invention, Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is an explanation showing the relationship between the annular die, cooling mandrel, and tubular film. 4 and 5 are explanatory diagrams of the conventional method. DESCRIPTION OF SYMBOLS 1... Tubular polycarbonate film manufacturing device, 2... Extruder, 3... Annular die, 4... Support tube, 5... Cooling mandrel, 6... Cooling ring, 7
. . . Inner roll, 8 . Patent applicant: Mitsubishi Yuka Co., Ltd.

Claims (2)

[Claims] (1) A tubular polycarbonate film extruded from an annular die attached to an extruder is continuously supplied and expelled with controlled supply pressure and amount of gas to the inside of the tubular polycarbonate film, which is then brought into contact with a cooling mandrel and cooled and solidified. A method for producing a tubular polycarbonate film, characterized in that the tubular polycarbonate film is continuously drawn while maintaining the tubular state. (2) A support tube rod is fixed coaxially to an annular die attached to an extruder, a cooling mandrel is concentrically fixed to the support tube rod, and the support tube is disposed between the annular die and the cooling mandrel. A nip roll consisting of a plurality of inner rolls having a cooling ring arranged concentrically with the rod and pivotally supported on the outer periphery of the support tube rod below the cooling mandrel, and outer rolls provided corresponding to each of these inner rolls. 1. A tubular polycarbonate film manufacturing apparatus, characterized in that a plurality of these are arranged, and the support tube rod is provided with a supply pressure/supply amount control gas continuous supply mechanism and a cooling mandrel internal heating medium supply mechanism.