JPH0531781A - Thermoplastic polyimide-based tubular film - Google Patents

Abstract

PURPOSE:To provide thermoplastic polyimide-based tubular film, which is produced by melt-extruding material mainly made of brand-new type thermoplastic polyimide-based resin different from the conventional polyimide-based resin in the form of film. CONSTITUTION:Polyimide-based resin with water content of 30 ppm or less is melt-extruded in the form of tube with an extruder, the inner surface of the cylinder of which is lined by special alloy and at the tip of the cylinder and near the head of which filters are arranged. Next, after being cooled by cooling system with a water tank, the resultant tubular resin is stretched and heat-set. By being turned into film as described above, thermoplastic polyimide- based tubular film having excellent dimensional accuracy and film thickness accuracy is obtained, resulting in expecting to be used in wide field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyimide tubular film formed by melt extrusion film formation.

[0002]

2. Description of the Related Art Conventionally, a polyimide film has been used as a heat-resistant film for various purposes. This polyimide film is mainly cast from a solution of a polyimide acid, which is a precursor of polyimide. It was general that a thin film was formed by the method described above, and then the film was formed by drying, dehydration and ring closure.

[0003]

[Problems to be Solved by the Invention] The polyimide film formed by the casting method has a poor productivity in the production, and since it uses a solvent, it has problems in environmental pollution and hygiene, and is expensive. It was a thing.

In order to solve the above problems, the present inventors have aimed to obtain a tubular film with extremely high dimensional accuracy and film thickness accuracy by a melt extrusion method using a material whose main component is a thermoplastic polyimide resin. Through various studies, the present invention was finally reached.

[0005]

Means for Solving the Problems The present invention is based on a dimensional accuracy obtained by melt extrusion film formation using a thermoplastic polyimide resin as a main component.
The present invention relates to a thermoplastic polyimide-based tubular film having excellent film thickness accuracy.

The thermoplastic polyimide-based resin according to the present invention is a completely new type of thermoplastic polyimide-based resin which is different from the conventional thermosetting or non-thermosetting imide type resin. As such a resin, for example, using a Koka type flow tester (die 10 mm × 0.1 mm, preheating time 5 min), a melting point near 380 to 420 ° C.
The melt viscosity measured in 1. can be 1,000 to 4,000 poise. Since such a melt-extruded film is formed using a thermoplastic polyimide resin having a low melt viscosity, a thermoplastic polyimide tube film having excellent dimensional accuracy and film thickness accuracy can be easily formed. At this time, a melt extrusion film of a thermoplastic polyimide resin having a melt viscosity other than the above range may be melt-extruded into a film, but the dimensional accuracy and the film thickness accuracy tend to be deteriorated in many cases, and the film formation is also difficult. Often there is. However, a thermoplastic polyimide resin having a melt viscosity outside the above range can be used depending on the application, and is not necessarily limited to the above range.

The thermoplastic polyimide resin of the present invention may be melt-extruded and formed into a film by itself, but it may be mixed with an inorganic filler in order to improve thermal conductivity, and there is no particular limitation to this. Absent. At this time, examples of such an inorganic filler include conductive carbon, talc, fisker titanate, boron nitride, and the like, but are not limited thereto. Further, a stabilizer, a lubricant, a surfactant, a pigment, a resin other than the polyimide resin, etc. may be added as long as the performance of the thermoplastic polyimide resin is not significantly deteriorated, and this is not particularly limited.

The thermoplastic polyimide resin according to the present invention is preferably dehumidified and dried so that the water content is 30 ppm or less when it is supplied to the extruder.
If it is more than ppm, the polyimito resin will easily decompose,
In many cases, a thermoplastic polyimide-based tubular film having excellent dimensional accuracy and film thickness accuracy cannot be formed due to a phenomenon such as deterioration of thermoplastic fluidity and generation of bubbles in the film, which is not preferable. Of course, the water content is 30
Even if it is supplied to the extruder in the state of more than ppm, it will not be any problem.

The thermoplastic polyimide-based tubular film of the present invention is generally formed into a tube by melt extrusion using an extruder equipped with an annular die. At this time, the cylinder of the extruder is nicked. In the case of steel, there are many cases where metal oxides are mixed in the film due to the oxidation of nitrogen nitride steel and the like, which tends to deteriorate the excellent performance of the thermoplastic polyimide film. It is often not preferred to use extruders that have them. However, if necessary, a cylinder made of nitrided steel may be used without any particular limitation.

In the cylinder of the extruder used for forming the thermoplastic polyimide film of the present invention, it is preferable that the inner peripheral surface of the cylinder is uniformly lined with a special alloy layer. Carbon, manganese, silicon, boron, nickel, cobalt, chromium, tungsten, carbide and the like in a hard corrosion-resistant alloy matrix can be exemplified as a lining material in which one kind or two or more kinds are uniformly dispersed, but it is not always limited thereto. Other materials may be used as long as they can prevent the oxidation of the nitrided steel.

The screw used in the extruder is preferably a rapid compression type, and L / D = 24 to 29 can be exemplified, but the screw is not necessarily limited to this value.
Further, the screw is generally plated with hard chrome, but this is not particularly limited.

If necessary, a filter for gel filtration may be attached to the tip of the cylinder or the vicinity of the head of the extruder in order to prevent gel molecules from being mixed in the film. At this time, as such a filter for filtration, for example, a laminate of a non-woven fabric of metal fibers having a large fiber diameter and a non-woven fabric of metal fibers having a small fiber diameter is used as a mesh-like protective layer and mesh-like one. It is preferable to use a fine mesh having a fineness of about 5 μ, which is sandwiched between (for example, stainless steel) support layers and then sintered and integrally processed, but this value is not particularly limited. Examples of such a filter include a leaf filter. However, the filter is not limited thereto, and any other filter may be used as long as it can filter gel molecules of the resin, and there is no particular limitation.

To form the thermoplastic polyimide tubular film of the present invention, an annular die is attached to the above-mentioned extruder, and a gas such as air is blown into the tubular extruded from the annular die to give a predetermined diameter ( The inflating method or the deflate method in which the diameter is smaller than the extrusion diameter of the die) and then cooling is preferable. At this time, the circular die is not particularly limited, but a spiral mandrel type is preferable,
It is not limited to this. There is no particular limitation as long as a T-die is attached to form a film on a flat film.

The cooling method is not particularly limited, and an appropriate method such as an inside mandrel method or an external cooling method may be adopted, and a particularly preferable example is a vacuum water tank. The vacuum water tank is a structure having a sizing sleeve and a cooling water tank whose inside is depressurized by a vacuum pump or the like, and the inner ring surface of the sizing sleeve, that is, the surface in contact with the tube is made of a material having good smoothness (for example, mirror finish). It is made of metal or fluororesin, etc., and has pores. Due to the pores, the surface in contact with the tubular film is in a reduced pressure state, whereby the outer diameter of the tubular film is regulated to a constant diameter along the sleeve inner ring surface,
At this time, if necessary, a small amount of water or the like may be supplied to the inner ring surface of the sleeve to form a thin water film between the inner ring of the sleeve and the outer surface of the tubular film. With such a vacuum water tank, the outer diameter of the tubular film is accurately regulated and cooled, and at the same time, the surface condition of the tubular film is improved and the dimensional accuracy is improved.

At this time, even if the cooling water tank has a general structure in which the outer surface of the tubular film is in direct contact with water, it may be in direct contact with direct water having a jacket through which a cooling medium flows in and out. There is no particular limitation as long as it has no cyclic structure.

The thermoplastic polyimide-based tubular film according to the present invention is not particularly limited as long as it is appropriately set as the extrusion conditions for forming the film with the above-mentioned extruder, but specifically, the supply parts 310 to 360. C, compression part 360-400
℃, melting section 370-410 ℃, die temperature 370-41
A value of about 0 ° C. can be exemplified. However, these values are not particularly limited. As for the spiral number of the screw, the supply parts 9 to 15, the compression parts 3 to 8 and the melting parts 7 to 8 can be exemplified as suitable ones, but this value is an example and is not necessarily limited thereto.

The thermoplastic polyimide-based tubular film of the present invention should be biaxially or uniaxially stretched and crystallized by heat setting if necessary in order to improve mechanical strength at high temperature. Is desirable. The crystallinity at the time of crystallization is not particularly limited, but the crystallinity is 10
It is preferably set to ˜35%. In this case, if the crystallinity is 10% or less, thermal deformation often occurs at 200 ° C. or higher, which is not preferable, and if the crystallinity is 35% or higher, the film becomes brittle and cracks are generated in the film, which is not preferable. Depending on the application, a value outside this range can be used. At this time, it goes without saying that the scope of the present invention is not required to perform the above-mentioned stretching and heat setting.

The stretching method is not particularly limited and may be any suitable method. The stretching conditions are not particularly limited, but the stretching temperature is preferably 250 to 350 ° C and the stretching ratio is preferably 1.2 to 3 times. When the stretching temperature is 250 ° C or less, uniform stretching tends to be difficult, and 350 ° C or more. In many cases, the stretching effect such as increase in strength is not recognized, and when the stretching ratio is 1.2 times or less, crystallization is not sufficient and improvement in strength and rigidity cannot be expected, and stretching is performed at 3 times or more. The accuracy of the film thickness tends to be lowered, and the higher the draw ratio is, the lower the accuracy of the film thickness is in many cases, which is not preferable. Of course, these values are merely examples, and the values may exceed the above range if necessary, and are not particularly limited.

The heat setting, which is performed as necessary, is generally performed continuously as it is after the stretching is completed, but the heat setting is not limited to this and may be performed by any other appropriate method. The heat setting temperature is not particularly limited, but is 30
0 to 350 ° C. is preferable, and if the temperature is 300 ° C. or lower, heat setting is insufficient and the dimensional accuracy is often lowered. If the temperature is 300 ° C. or higher, mechanical performance tends to be lowered.
The heat setting time varies depending on the heat setting temperature, but is usually 10 to 30 minutes, and if it is less than 10 minutes, heat setting is not sufficient and dimensional stability often deteriorates.
If it is more than a minute, the film thickness accuracy of the film tends to decrease, but depending on the application, a film having a value outside these ranges can be formed, and such a value is not particularly limited.

The above-mentioned thermoplastic polyimide film is preferably formed in a clean room in order to prevent foreign matters from entering the film, but the invention is not particularly limited to this. At this time, the cleanness of the clean room is preferably 10,000 or less in the number of particles of 0.1 μ or more contained in 1 cubic foot of air, and the smaller the number, the higher the yield can be expected. Needless to say, it does not have to be performed in a clean room as in the conventional case, and the film may be formed in an ordinary room depending on the application.

The thermoplastic polyimide tubular film formed as described above is excellent in heat resistance, mechanical properties, dimensional stability, film thickness accuracy, flame retardancy, abrasion resistance, abrasion resistance, electrical properties, etc. and is flexible. Printed circuit boards, insulating films for electrical parts, seat belts, food trays, medical parts,
There are no particular restrictions on the use of optical parts and equipment as they can be expected to expand.

The present invention will be described below with reference to examples.

[0023]

[Examples] Pellets of a thermoplastic polyimide resin (glass transition temperature 250 ° C, melting point 388 ° C, melt viscosity 2927 poise measured by Koka type flow tester 420 ° C) were circulated in a tray dryer at a hot air temperature of 300 ° C for 2 hours. After drying and crystallizing only the surface of the pellet, it is dried at 250 ° C for 10 hours in a hermetic dehumidifying hopper dryer to obtain a water content of 1
It was set to 0 ppm. Then, while supplying the pellets to the hopper and replacing the atmosphere with nitrogen, the cylinder temperature is 360 to 390 ° C.
The inner surface of the heated cylinder was sent to an extruder lined with X-Alloy 800 (manufactured by Fuji Industries Co., Ltd.) and melted, and passed through the leaf type filter of 5 μm installed between the tip of the cylinder and the die,
Melt extrusion was carried out from an annular die having an outer diameter of 32φ, an inner diameter of 30φ and a temperature of 390 ° C. The melt-extruded molten film was sucked into a sizing sleeve having an inner diameter of 245φ by a vacuum water tank system and cooled to form a thermoplastic polyimide tube film. This film has a thickness of 50μ ± 5μ and a perimeter of 7
It was 5.4 ± 0.5 mm. The thus obtained tubular film was stretched twice at 290 ° C. in the circumferential direction and 1.2 times in the machine direction, and then heat set at 310 ° C. to obtain a film having a thickness of 20 ± 2 μm. Circumference 15
It was 0.8 ± 0.2 mm. The thermoplastic polyimide tube-shaped film has a cleanness of 10,000.
Since the film was formed in the clean room of No. 3, contamination of foreign matter was not recognized.

[0024]

[Comparative Example] Extrusion film formation could not be performed with a thermosetting polyimide resin.

[0025]

The present invention is as described above. The thermoplastic polyimide-based tubular film of the present invention is particularly preferable because it is excellent in dimensional accuracy and film thickness accuracy.
(Flexible printed circuit board), insulation film for electric wire, precision electric / electronic member using heat resistance, such as copying machine,
It is suitable for various belts of printers, such as a fixing belt, and has good dimensional accuracy, so it can be used as a driving belt for precision equipment. Further, it can be expected to be used in various fields such as food, medical, optical parts, and other fields.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsutomu Yoshida             Gunse Co., 163 Morikawaramachi, Moriyama City, Shiga Prefecture             Shiga Research Institute (72) Inventor Satoshi Wanaka             1 Hirano, Murakuno, Oita, Konan City, Aichi Prefecture             Nze Stock Company Inside the Gangnam Factory

Claims (5)

[Claims] 1. A thermoplastic polyimide-based tubular film formed by melt-extrusion film formation containing a thermoplastic polyimide-based resin as a main component. 2. The thermoplastic resin composition according to claim 1, wherein a melt-extrusion film is formed by an extruder having a cylinder having an inner surface coated with a lining layer in which a fine particle substance is uniformly dispersed in a corrosion-resistant alloy matrix. Polyimide tube film. 3. A composite non-woven fabric obtained by laminating a non-woven fabric made of metal fibers having a large fiber diameter and a non-woven fabric made of metal fibers having a small fiber diameter, which is placed between a protective layer and a support layer and sintered. The thermoplastic polyimide tubular film according to claim 1, which is formed by melt extrusion film formation by an extruder equipped with a filtration filter. 4. When supplied to an extruder, it has a water content of 30.
The thermoplastic polyimide-based tubular film according to claim 1, wherein the thermoplastic polyimide-based resin having a ppm or less is melt-extruded to form a film. 5. The thermoplastic polyimide tubular film according to claim 1, which is formed by melt extrusion film formation in a clean room of 10,000 class or less.