JP2617975B2 - Method and apparatus for manufacturing tubular resin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and apparatus for producing a tubular resin film having high dimensional accuracy and having no seams or folds.

(Prior art) A tubular resin film drives various devices by utilizing its mechanical properties such as moldability, lightness and strength, and its relatively easy control of electrical properties and heat resistance. It is used as a belt, a photoreceptor base belt of an electrophotographic apparatus, an intermediate transfer belt, and the like. In these applications, the uniformity of the diameter in the width direction and the uniformity of the thickness in the width direction of the belt when the belt is formed into a loop shape are particularly important, and therefore, as shown in FIG. The both ends of the cut flat film cut into a predetermined length are used as a joint belt (a). For this reason, the belt has a substantially uniform diameter in the width direction, but has a seam (b).

(Problems to be Solved by the Invention) When such a joint (b) is used as a drive belt, a minute vibration is generated at the joint (b), which limits the application to precision equipment. There is a point.
When used as a photoreceptor substrate belt, the seam (b) cannot be used because the photosensitive performance of the seam (b) is different from that of the other parts. Even in the intermediate transfer belt, there is a problem that the seam (b) causes an image defect and the like.

Therefore, in order to form a seamless belt, as shown in FIG. 5, a polycarbonate resin is extruded in a tubular shape from an annular die (c), and cooled and solidified to form a tubular film (d). Means have been proposed in which a belt is cut into a circle.

However, the diameter of the tubular film corresponding to the uniformity of the diameter in the width direction of the belt formed in this way is changed from the molten state to the solidified state between the annular die (c) and the take-off nip roll (e). In the tubular film, the pressurized gas is sealed and a cooling ring (f) near the annular die (c) is sequentially blown around the tubular film by the cooling gas. The diameter of the tubular film is determined by the balance between the improved melt tension of the tubular film in the molten state and the thickness of the tubular film which becomes thinner from the annular die to the nip roll, so that the diameter of the tubular film is made uniform. There is a problem that it is difficult.

Moreover, in order to seal the pressurized gas inside the tubular film, it is essential to use a take-off nip roll.When the nip roll is used, the tubular film is folded in two, and the fold portion is deformed beyond the yield point elongation. As a result, two folds parallel to the longitudinal direction of the tubular film are formed, which eventually causes the same problem as the joint.

As described above, it was impossible to obtain a belt having no seams and no folds in which the diameter of the belt was uniform in the width direction of the belt and the thickness of the belt in the width direction was uniform.

(Means for Solving the Problems) The present invention provides a tubular resin film having a uniform diameter in the width direction of the belt, a uniform thickness in the width direction, and no seams or folds. Claim (1) is to continuously supply and eliminate a gas whose supply pressure and supply amount are controlled to the inside of a tubular resin film extruded from an annular die mounted on an extruder. The tubular resin film is brought into contact with a cooling mandrel having a diameter of 0.5 to 0.99 times the die lip diameter of the annular die to cool and solidify the tubular resin film, so that the tubular resin film is continuously drawn while maintaining the expanded tube state. A method for producing a tubular resin film. A second aspect of the present invention is to fix a support pipe rod coaxially to an annular die mounted on an extruder and fix a cooling mandrel concentrically to the support pipe rod. A cooling ring disposed concentrically with the support tube rod, a plurality of inner rolls pivotally supported on the outer periphery of the support tube rod below the cooling mandrel, and outer rolls respectively provided corresponding to these inner rolls Arrange multiple sets of nip rolls consisting of
A tubular resin film manufacturing apparatus characterized in that a supply pressure / supply amount control gas continuous supply / discharge mechanism and a heating medium supply mechanism in a cooling mandrel are attached to the support pipe rod.

(Example) FIGS. 1 and 2 show a tubular resin film manufacturing apparatus 1.
As shown in FIG. 3 and FIG. 3, a support tube 4 is fixed to an annular die 3 mounted on the extruder 2 so as to be coaxial with the annular die 3, and a cooling mandrel 5 is fixed to the support tube 4 concentrically. .

Next, a cooling ring 6 is arranged between the annular die 3 and the cooling mandrel 5 concentrically with the support pipe rod 4, and is pivotally supported on the outer periphery of the support pipe rod 4 below the cooling mandrel 5. The inner rolls 7,7,7… are provided, and these inner rolls 7,7,7…
Are provided correspondingly to the nip rolls 9, 9, 9,... Composed of the inner roll 7 and the outer roll 8, respectively.
Are provided in multiple sets.

The support pipe rod 4 is supplied with a supply medium for a supply pressure / supply amount control gas continuous supply / discharge mechanism 10 and a cooling medium in the cooling mandrel 5.
A cooling medium in-mandrel heat medium supply mechanism 11 that circulates is provided.

The supply pressure / supply amount control gas continuous supply / discharge mechanism 10 includes a supply pipe 13 connected to an outlet 12 through the inside of the support pipe rod 4.
And a discharge pipe 15 that passes through the inside of the support pipe rod 4 and is connected to the blow-in port 14.

A heating medium supply mechanism 11 into the cooling mandrel 5 is provided with an inflow port that opens through the support pipe rod 4 into the cooling mandrel 5.
A supply pipe 17 connected to a supply pipe 16 and a discharge pipe 19 connected to an outlet 18 in the cooling mandrel 5 through the support pipe rod 4.
And

The tubular resin film is manufactured by such a tubular resin film manufacturing apparatus as follows.

That is, the molten film (a) extruded into a tube shape from the annular die 3 mounted on the extruder 2 is cooled by the cool air blown from the cooling ring 6 on the outer periphery, and supplied to the inside through the supply pipe 13 through the supply pipe 13. Gas with controlled supply (b)
Is continuously supplied and discharged through a discharge pipe 15, while being always kept at a predetermined inner pressure, by being brought into contact with a cooling mandrel 5 to be cooled and solidified, and then circumferentially at 90 ° intervals around the support pipe rod 4. The nip rolls are arranged between the nip rolls 9,9,9,9 and pulled while maintaining the tubular shape.

Therefore, even if the taken-out tubular resin film (F) is cut into a ring shape, there is no seam or fold.

The resin used in the present invention is not particularly limited, and various resins may be used according to the application and required mechanical and electrical properties. Representative examples include polycarbonate comprising bisphenol A, copolymer of bisphenol A and halogenated bisphenol A, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, ethylene-hexa Examples thereof include a fluoropropylene copolymer and a hexafluoropropylene-perfluoroalkylvinyl ether copolymer. Also, a mixture of these resins can be used.

The MFR of the resin used in the present invention according to JISK6719 is
It is preferably 0.05 g / 10 min or more and 20 g / 10 min or less, preferably 0.
It is 1 g / 10 min or more and 10 g / 10 min or less, and if the MFR is less than 0.05, the ductility of the molten tubular resin is lost and uniform deformation becomes difficult, so it is difficult to obtain a uniform thickness of the tubular resin film. There is.

On the other hand, when the MFR exceeds 20 g / 10 minutes, the melt tension of the tubular resin film in the molten state decreases, and as a result, the tube shape becomes unstable during the process of solidification from the molten state, so that the diameter and thickness are uniform. There is a tendency that it is difficult to obtain a tubular resin film.

If necessary, a function-imparting component such as a conductivity-imparting component, a component for improving thermal stability, fluidity, and appearance may be added.

The direction of the annular die in the present invention may be upward or downward with respect to the extruder. However, when the film production speed is relatively slow, if the film is oriented upward, the film may be deformed by its own weight and may be folded. Therefore, downward is preferable.

The structure of the annular die is not limited at all, but a spiral die is preferable in terms of uniformity of the thickness of the tubular film, and the annular die may be a single-layer die or a multilayer die. In each case, the resin of each layer may be the same or different.

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

Preferably, the temperature environment around the molten tubular film between the annular die and the cooling mandrel is in a stable state, and a uniform temperature-controlled gas is 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
If the thickness is less than 20 mm, the tubular molten film is sharply deformed between the die lip and the cooling mandrel, so that it is easy to cut and continuous production becomes difficult. On the other hand, if it exceeds 500 mm, the tube shape becomes unstable because the proportion of the molten tubular film having a small melt tension in the molten tubular film between the die lip of the annular die and the cooling mandrel is increased. , Making stable continuous production difficult.

The diameter of the die lip diameter D ₁ and the cooling mandrel annular die
Referring to FIG. 3, the relationship with D ₂ is D ₂ = 0.99 D ₁ or less, and D ₂ =
0.5 D ₁ or more, preferably D ₂ = 0.6
D ₁ or more, and more preferably D ₂ = 0.8D ₁ or more. If the diameter D ₂ of the cooling mandrel exceeds 0.99D _1, tubular film of molten vertical body is generated by the stick-slip at a position in contact with the cooling mandrel, uniform film thickness can not be obtained in the longitudinal direction. On the other hand, D ₂
If it is 0.5D less than _1, since the tubular film in a molten state is not in contact simultaneously circumferentially cooling mandrel can not be obtained a uniform film thickness.

The most desirable form as shown in FIG. 3, than the diameter D ₁ of the die lip, the diameter D ₂ of the cooling mandrel small cities,
Furthermore die lip diameter of the diameter D ₃ of the tubular film in a molten state cooling mandrel located between the cooling mandrel
As less than D _2, it may be cooled and solidified by contacting a tubular molten film to a cooling mandrel.

2mmR or more and 20mm on the periphery of the cooling mandrel on the annular die side
It is preferable to chamfer below R.

The longitudinal length of the cooling mandrel is preferably 10 mm
As described above, the diameter is preferably 20 mm or more and three times or less the diameter of the die lip. If the diameter is less than 10 mm, the control of the internal pressure in the space surrounded by the die lip, the cooling mandrel and the molten tubular film becomes unstable. Exceeding the die lip diameter by three times increases the friction between the cooled and solidified tubular film and the side of the cooling mandrel, and the cooled and solidified film becomes plastic between the cooling mandrel and the nip roll that follows the cooling mandrel. It deforms and the thickness of the tubular film becomes uneven.

The surface state of the cooling mandrel is preferably a so-called satin finish treatment having irregularities of 0.3 μ or more, preferably 0.5 μm to 25 μm, more preferably 1 μm to 1 μm.
It is good to be 0 μm or less. A sticky slip occurs at the position where the molten tubular film with irregularities less than 0.3μ in contact with the cooling mandrel, making it impossible to obtain a film of uniform thickness in the longitudinal direction. As well as the occurrence of scratches, the control of the internal pressure in the space surrounded by the die lip, the cooling mandrel, and the molten tubular film becomes unstable.

The material of the cooling mandrel is desirably metal, ceramics, wood, cloth, or the like, and is preferably metal or ceramics. Plastic materials such as Teflon are not preferred because stick-slip easily occurs.

The cooling mandrel is a perfect circle with a constant diameter in the longitudinal direction, or a large diameter on the side close to the die lip
It may have an inverted tapered shape having a slope of 0 or less.

The surface of the cooling mandrel is desirably 0 ° C or more and 200 ° C or less, preferably 10 ° C or more and 150 ° C or less,
More preferably, the temperature is from 20 ° C to 130 ° C. When the temperature is lower than 0 ° C, the molten tubular film rapidly cools and solidifies as soon as it comes into contact with the cooling mandrel, so that the molten tubular film does not come into contact with the cooling mandrel stably and continuously. Film cannot be obtained. If the temperature exceeds 200 ° C., stick-slip occurs on the cooling mandrel, and a film having a uniform thickness in the longitudinal direction cannot be obtained.

Although a known means can be used to adjust the temperature of the cooling mandrel, it is desirable that the heat medium whose temperature is adjusted circulates inside the cooling mandrel from the viewpoint of temperature control accuracy and temperature control capability.

In a space surrounded by a die lip, a cooling mandrel, and a tubular film in a molten state, it is necessary to continuously supply a gas whose supply amount and supply pressure are controlled, and to continuously discharge the gas. If the film is in a closed state, it may cause small film unevenness that does not affect the uniformity of the film thickness, or the molten tube between the die lip and the cooling mandrel may evenly and simultaneously Contact is lost, and a film having a uniform thickness cannot be obtained.

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

Referring to FIGS. 1 and 3, in the vicinity of the tubular film in the molten state in contact with the cooling mandrel, a tube cut in the molten state with respect to a cross section taken along a vertical plane passing through the center of the annular die and the center of the cooling mandrel. A point at which the film is in contact with the cooling mandrel is point A, a point on the tubular film immediately above point A is point B, and a point passing through point A is parallel to a line passing through the center of the annular die and the center of the cooling mandrel. If the point on the line is point C and the cooling mandrel is located below the annular die, the points A and C are respectively associated with the left side toward the cooling mandrel and above the annular die with respect to the right side toward the cooling mandrel. Line AC connecting points
When the CAB between the point AB and the line AB connecting the points A and B is-in the clockwise direction and + in the counterclockwise direction, the CAB is preferably +20 or less and -45 or more, and preferably +10 or less. The angle is preferably −30 ° or more, more preferably ± 0 ° or less and −20 ° or more. If the {CAB} exceeds +20, the molten tubular film will not contact the cooling mandrel at the same time, and a film having a uniform thickness cannot be obtained. Meanwhile, ∠CAB
Is less than -45 °, stick slip occurs on the cooling mandrel, and a film having a uniform thickness cannot be obtained.

The means for continuously unfolding the cooled and solidified tubular resin film is provided at least two times around the supporting tube rod located inside the continuously moving tubular film and opposite the annular die. Attach inner rolls that are rotatable or non-rotatable at more than two places, and between these nip rolls and the outer rolls that are arranged correspondingly outside the tubular film and covered with rubber elastic material, This is made possible by sandwiching a tubular film.

It is preferable that the driving force for pulling the tubular film is applied to the outer roll side in view of the complexity and operability of the apparatus.

The tubular film taken by the nip roll is
The film can be wound up while retaining the gas in the tubular film with a deformation amount within the allowable range for the intended use, and if slight deformation is not allowed, the tubular film pulled from the nip roll May be cut into a desired length in a ring shape.

The thickness of the tubular resin film obtained by the present invention is desirably 10μ or more and 1000μ or less, preferably 15μ or more.
It is 500 μm or less, more preferably 20 μm or more and 300 μm or less. When the thickness of the film is less than 10 μm, the film is plastically deformed when being pulled by a nip roll, and a film having a uniform thickness cannot be obtained. If it exceeds 1000 μm, cooling on the cooling mandrel becomes difficult.

In addition, the obtained tubular resin film is subjected to heat treatment under tension at a temperature of 200 ° C. or less for the purpose of imparting thermal temporal dimensional stability and correcting small plastic deformation in an allowable range. Good.

With reference to FIGS. 1, 2 and 3, an example of the present invention when polycarbonate is used as the resin will be described.

The outer diameter of the die lip is 75mmφ, the lip spacing is 0.5mm, and the support pipe rod 4 penetrates the annular die 3 which is a 4-row spiral spiral die with a lip interval of 0.5mm. Then, a steel cooling mandrel 5 sprayed with alumina ceramics so as to have a surface irregularity of 2 μm is attached at a position 60 mm from the end face of the annular die 3, and a rubber inner 10 mm φ is placed 100 mm below the lower end of the cooling mandrel 5. Attach rolls 7,7, these two inner rolls 7,7
In addition, each is located outside the tubular film and is driven by a motor (not shown).
mmφ rubber outer rolls 8,8, nip rolls 9,9 consisting of opposing inner roll 7 and outer roll 8 are provided, and polycarbonate resin (Mitsubishi Gas Chemical, Iupilon E-2000, MFR = 5g / 10min) ) From a 50mmφ extruder to 290 ℃
While supplying air at a rate of 0.03 kg / cm ² and INl / min from the supply pipe 13 while blowing air at 100 ° C. from the cooling ring 6.
After bringing the molten tubular film with {CAB -5} into contact with the cooling mandrel 5 circulating 80 ° C. hot water at 2 / min from the supply pipe 13, the nip roll
The film was taken out at 9 m / min at 5 m / min to obtain a tubular polycarbonate film having a film thickness of 100 μm.

The resulting 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 was measured in accordance with JIS K7113. The elastic modulus is 22000k in the circumferential direction
g / cm ² , 23000 kg / cm ² in the longitudinal direction, with a thermal shrinkage of 0% at 140 ° C. and excellent mechanical and thermal properties.
It was a tubular polycarbonate film having a uniform diameter and thickness and no folds.

(Effects of the Invention) The present invention can produce a tubular resin film having a uniform diameter and thickness and having no seams or folds. Since it has no folds, it is suitable as a drive belt and can be used for many purposes as an industrial material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of the apparatus of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is an explanation showing the relationship among an annular die, a cooling mandrel and a tubular film. FIG. 4, FIG. 4 and FIG. 5 are explanatory diagrams of the conventional method. DESCRIPTION OF SYMBOLS 1 ... Tubular resin film manufacturing apparatus, 2 ... Extruder, 3 ... Annular die, 4 ... Support tube rod, 5 ... Cooling mandrel, 6 ... Cooling ring, 7 ... Inner roll, 8 ...
Outer roll, 9: Nip roll, 10: Supply pressure / supply amount control gas continuous supply mechanism, 11: Heat medium supply mechanism in cooling mandrel.

Claims (2)

(57) [Claims] 1. A method for controlling the supply pressure and the supply amount of gas to and from a tubular resin film extruded from an annular die mounted on an extruder while continuously supplying and removing the gas. The tubular resin film is brought into contact with a cooling mandrel having a diameter of 0.5 to 0.99 times to cool and solidify the tubular resin film, and to continuously withdraw while maintaining the expanded tube state. Resin film manufacturing method. 2. A supporting pipe rod is fixed to an annular die mounted on an extruder coaxially, and a cooling mandrel is fixed to the supporting pipe rod concentrically, and the cooling mandrel is provided between the annular die and the cooling mandrel. A nip roll comprising a plurality of inner rolls provided with a cooling ring concentrically with the support pipe rod and supported on the outer periphery of the support pipe rod below the cooling mandrel, and outer rolls provided respectively corresponding to the inner rolls; Are arranged in multiple sets,
A tubular resin film manufacturing apparatus, characterized in that a supply pressure / supply amount control gas continuous supply / discharge mechanism and a heating medium supply mechanism in a cooling mandrel are attached to the support pipe rod.