JPH0586751B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a composite film. More specifically, it is a composite film made by laminating a polyphenylene sulfide film on at least one side of a biaxially oriented polyester film, and has excellent film formability, mechanical properties, and thermal properties, so it is suitable for electrical insulation applications and magnetic recording media applications. It is suitable for [Prior art] In recent years, polyethylene terephthalate film has been widely used as a general-purpose industrial material film, but it has been used for electrical insulation purposes, magnetic recording media, etc. in order to save energy, reduce the size and weight of equipment, and improve reliability. There is a need for a film with better heat resistance than polyethylene terephthalate. For example, on floppy disks, the ``track''
Information is recorded in a number of thin annular recording areas called concentric circles arranged on the disk surface.Recently, in order to increase the recording capacity, efforts have been made to increase the track density or It is required to use a magnetic agent with high coercivity. The former requires lowering the humidity expansion coefficient, and the latter requires vapor deposition, sputtering, etc. for perpendicular magnetic recording, and both require heat resistance and dimensional stability. Also, in ordinary magnetic tape,
Vapor-deposited tapes and perpendicular magnetic recording tapes are being actively developed, and heat-resistant materials are needed to replace polyethylene terephthalate in this field as well. Polymer film has recently been developed as a film that meets this purpose.
p-phenylene sulfide film is attracting attention. Although poly-p-phenylene sulfide film essentially has advantages such as excellent heat resistance and a low coefficient of humidity expansion, it has the disadvantages of high crystallization rate and poor moldability. In particular, it is nearly impossible to form films with a thickness exceeding 50 μm, such as those for electrical insulation and floppy disks, due to insufficient cooling during casting. On the other hand, when used as a magnetic recording tape, surface smoothness is required;
Compared to polyethylene terephthalate film, it was much more difficult to control the surface roughness, and it was impractical. [Problems to be Solved by the Invention] The purpose of the present invention is to take advantage of the advantages of poly-p-phenylene sulfide film, such as its good heat resistance and low coefficient of humidity expansion, while improving its moldability and The object of the present invention is to provide a composite film suitable for electrical insulation films, magnetic recording media, etc. by improving film formability and imparting slipperiness to the film. [Means for solving the problem] That is, the gist of the present invention is that 70 mol% or more of the repeating units on at least one side of the polymer film have the following structural formula ().

The present invention relates to a composite film characterized in that layers made of biaxially oriented polyphenylene sulfide films represented by the formula are laminated. In the present invention, the biaxially oriented polyester film is not particularly limited, but examples include polyethylene terephthalate film, wholly aromatic polyester film, polyethylene-2,6-naphthalate film, polyethylene-α,β-bis(2-
Examples include chlorophenoxy)ethane-4,4-dicarboxylate film. Preferably, it is a biaxially oriented polyester film such as a biaxially oriented polyethylene terephthalate film or a biaxially oriented polyethylene-2,6-naphthalate film. In addition, the polyphenylene sulfide film in the present invention has the following structural formula ()

Refers to those containing 70 mol% or more, preferably 80 mol% or more of repeating units represented by the formula. If the content of such loosely bonded phenylene sulfide units is less than 70 mol%, the crystallinity of the polymer will decrease, so when a film made of such a polymer is used as a base film, it will have low heat resistance, which is undesirable. . The remaining 30 mol% or less of the repeating units of the polymer are metaphenylene sulfide units (the following structural formula), ether units (), sulfone units (), biphenyl sulfide units (), and naphthylsulfide units. The copolymerization component can be composed of an id unit ( ), a substituted phenyl sulfide unit ( ), a trifunctional phenyl disulfide unit ( ), etc., but the content of such copolymerized components is preferably 20 mol % or less.

【formula】

[ka]

[ka]

[ka]

[ka]

[Chemical formula] (Here, R represents an alkyl group having 1 to 10 carbon atoms, a nitro group, a phenyl group, an alkoxy group having 1 to 10 carbon atoms, etc.)

[C] The characteristic melt viscosity of polyphenylene sulfide in the present invention is at a temperature of 300℃ and an apparent shear rate.
500 to 12000 poise under 200sec ^-1 conditions, especially 700
A range of 7,000 poise is preferred from the viewpoint of film formability, surface smoothness, etc. The biaxially oriented polyphenylene sulfide film, when used for floppy disks, has an in-plane birefringence of 0.04 or less and a coefficient of thermal expansion in the direction of the main orientation axis at 25°C of 2.8×10 ^-5 / ℃ or less (especially preferably 2.4×10 ^-5 /℃ or less).
If the temperature exceeds this range, the floppy disk finally obtained will be susceptible to off-track due to temperature changes, which is unsuitable. ) is preferable. The average surface roughness of the biaxially oriented polyphenylene sulfide film is not particularly limited for electrical insulation applications, etc., but when used for magnetic recording media applications, it is 0.001 to 0.03 μm (more preferably 0.001 to 0.03 μm).
0.003-0.02μm, more preferably 0.003-0.015μm)
It is desirable that the height is within the range of 1.16 μm.
It is desirable that the density of the above coarse protrusions is 3.0 pieces/cm ² or less (more preferably 2.0 pieces/cm ² or less). In the present invention, when used as a magnetic recording medium, the magnetic layer is provided on the surface of the polyphenylene sulfide film, whether it is a magnetic tape or a floppy disk.
Therefore, in the case of a floppy disk, for example, in a three-layer structure in which the center layer is a polyethylene terephthalate film and both sides are polyphenylene sulfide layers, magnetic layers are provided on the front and back surfaces of the polyphenylene sulfide films. On the other hand, in a magnetic tape, a magnetic layer is provided on a polyphenylene sulfide film having a two-layer structure consisting of a polyphenylene sulfide film and, for example, a polyethylene terephthalate film. Therefore, the surface opposite to the magnetic layer must play the role of imparting running properties to the magnetic tape, and its surface average roughness is 0.001 to 0.03 μm, preferably the surface average roughness of the magnetic layer is 0.001 to 0.03 μm.
It is 0.002 μm or more and 0.03 μm or less. Moreover, it is preferable that the Masatsu coefficient at that time is 0.1 to 0.7. In a film with a three-layer structure in which the center layer is a polyester film and the surface layer is a polyphenylene sulfide film, the two surface layers of the polyphenylene sulfide film must have substantially the same composition as each other. is preferable in terms of curling. On the other hand, in the case of a film having a two-layer structure of a polyester film and a polyphenylene sulfide film, it is preferable to adjust the melt viscosity and film thickness to prevent curling. Here, as a method for laminating three layers, there are methods such as pasting together a separately prepared polyester film and polyphenylene sulfide film using an adhesive, or extrusion lamination on a polyester film. However, a coextrusion method in which the layers are laminated in a die is most preferred. The unstretched film thus obtained is biaxially stretched and heat-set, and the thickness of the polyphenylene sulfide film after biaxial stretching is preferably 1 to 20 microns. On the other hand, the thickness of the polyester film is not particularly limited, but it is preferably half or more of the total thickness. Next, the method for manufacturing the composite film of the present invention will be specifically described. First, as a method for polymerizing polyphenylene sulfide used in the present invention, alkali sulfide and p-dihalobenzene (required amounts of other components may be included when copolymerizing) are reacted in a polar solvent at high temperature and pressure. Use the method of In particular, it is preferable to react sodium sulfide and p-dichlorobenzene in an amide-based high-boiling polar solvent such as N-methylpyrrolidone. In this case, in order to adjust the degree of polymerization, so-called polymerization aids such as caustic alkali and alkali metal carboxylic acid salts are added.
Most preferably, the reaction is carried out at °C. The pressure within the polymerization system and the polymerization time are appropriately determined depending on the type and amount of the auxiliary agent used and the desired degree of polymerization. generated in the polyphenylene sulfide thus obtained.
If NaCl remains, it will form as coarse protrusions on the film surface, so it is necessary to remove it as much as possible. If necessary, fine particles are uniformly dispersed in the polyphenylene sulfide thus obtained and extruded to form chips as a polymer raw material. (Polymer A) On the other hand, the polyester is made to contain internal particles and/or additive particles in a required amount according to a known method and is chipped as a polymer raw material. (Polymer B) Polymer A and Polymer B thus obtained were dried separately, melted in separate extruders, and extruded in a multilayer state through a T-die by coextrusion using a multi-manifold method or a combining adapter method. The sheet is continuously extruded from the wafer, cast onto a cooled metal drum, and rapidly solidified to form an unoriented amorphous sheet. For the molten film on this metal drum,
It is preferable to apply a positive or negative electrostatic charge to bring the film into close contact with the drum. Next, the sheet thus obtained is biaxially stretched. Here, as for the stretching method, the unstretched film described above is stretched at 80°C to 120°C, preferably 80°C to 110°C.
The film is stretched 2.0 to 5.0 times in one direction using a roll or tenter-type stretching rod. At that time, the stretching may be performed in one step or in multiple steps. The uniaxially stretched film obtained in this way is stretched in a direction perpendicular to the first stage using a tenter or roll.
℃~150℃ Preferably 1.5~90℃~140℃
By sequentially biaxially stretching 5.0 times, a biaxially oriented film can be obtained. In addition, the unstretched film was heated to 80°C.
It is also possible to obtain a biaxially oriented film by simultaneously biaxially stretching 2.0 to 5.0 times at ~150°C. The biaxially oriented film thus obtained may be heat-set as it is, but may be re-stretched in the longitudinal and/or transverse directions if necessary. In any case, the biaxially oriented film thus obtained has an increased density and
180 on the polyphenylene sulfide side to improve dimensional change properties, heat resistance, mechanical strength, etc.
℃ or more, 290℃ or less, polyester side: 180℃ or more
Heat set at 260℃ or less. Since the thickness of the polyphenylene sulfide film is small even when the composite film obtained in this way is thick, it is possible to stretch the film by suppressing crystallization during casting as much as possible. It is extremely superior in that it can maintain the advantages of polyphenylene sulfide film. Thus, it can be suitably used for electrical insulation purposes and high-density floppy disk applications. On the other hand, for magnetic tape applications, it is possible to create high-density tapes such as vapor deposition and perpendicular magnetization by applying a magnetic layer on a heat-resistant polyphenylene sulfide film. By adjusting the degree by known means, it is possible to impart flatness and slipperiness, which is difficult to achieve with polyphenylene sulfide film alone. The composite film thus obtained is particularly suitable as an electrical insulation film, a floppy disk film, and a magnetic tape film as described above, but it can also be used for other purposes as required, such as packaging, agriculture, photography, etc. It can also be used for adhesive tapes, building materials, decorations, etc. For example, packaging for foods, miscellaneous goods, and pharmaceuticals, films for greenhouse cultivation, bases for adhesive or pressure-sensitive tapes coated with adhesive on one or both sides, photographic films for printing plates, aerial film reproductions, photographic films for copying, 8 mm cine films. , X-ray film, dry plate film, and after matting, it can be used for tracing and copying films,
Video or audio, base film for 8m/m video, magnetic disk base, base for hot stamping, capacitors, transformers, coils, motors, high temperature magnetic wires, flat wires, printed circuit boards, diaphragms and seals for batteries such as fuel cells. Can be used for linings, protective clothing, decorative laminate films, wall films, speaker vibration films, thermal transfer films, membrane switches, liquid crystal panels, polarizing plates, solar cell substrates, flexible printed circuit boards, etc. Of course, it is also possible to use it as a composite material by laminating it with other films or combining it with paper or metal. Particularly preferable application examples using the composite film of the present invention are listed below. (a) At least 70 mol% of repeating units on both sides of the biaxially oriented polyester film have the following structural formula ()

〔Example〕

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1, Comparative Examples 1 and 2 The polyphenylene sulfide polymer raw material contained 98 mol% of p-phenylene sulfide units;
2 mol% m-phenylene sulfide unit
A copolymerized polyphenylene sulfide polymer raw material A having a melting point of 272° C. was prepared according to a conventional method. On the other hand, as a polyester polymer raw material, polyethylene-2,6-naphthalate polymer raw material B having a melting point of 272 DEG C. was produced according to a conventional method. Polymer raw material A and polymer raw material B are extruded using separate extruders and co-extruded to produce polyphenylene sulfide of 100 μm each on the front and back sides and 800 μm of polyethylene-2,6-naphthalate in the center layer.
An unstretched film was prepared to have a thickness of 1000μ. This unstretched film was stretched 3.5 times in length and width,
Heat treatment was performed at 270°C for 30 seconds at a constant length to obtain a 75μ film. (Example 1) Also, polyphenylene sulfide film alone (Comparative Example 1), polyethylene-2,
A 75μ film was similarly formed using a single 6-naphthalate film (Comparative Example 2). The results are shown in Table 1.

【expressed.
From the above, it can be seen that the film of the present invention is particularly excellent as a film for electrically insulating materials. Example 2 The film prepared in Example 1 was surface-treated with argon plasma for 10 seconds in 0.6 Torr argon gas, and treated with 60% by weight of dimer acid polyamide (Henkel product Persalon 1165) and novolak epoxy resin. (Ciel product Epicoat #152) 30% by weight and 2% by weight of imidazole were mixed and dissolved in dimethylformamide, and a varnish with a concentration of 40% by weight and a viscosity of 2 poise was applied.
After drying for 2 minutes and at 140°C for 1 minute, copper foil was laminated to produce a copper clad board, which was cured at 100°C for 1 day in a nitrogen gas atmosphere. The performance of this copper clad board is shown in Table 2.

[Table] From the above results, it can be seen that the film of the present invention is extremely excellent for use in printed wiring boards. Example 3, Comparative Example 3 A polyphenylene sulfide film containing fine particles classified and dispersed in the polyphenylene sulfide film in Example 1 was prepared. The surface roughness of the film is
The average surface roughness Ra was 0.015 μm, the number of coarse protrusions with a height of 1.16 μm or more was 0.2/cm ² , the birefringence was 0.010, and the thermal expansion coefficient at 25°C in the direction of the main orientation axis was 2.2×10 ^-5 /°C. . A magnetic paint consisting of the composition shown below was prepared on this surface, and this was applied to both sides using a spinner to a thickness of 3.0 μm (after drying) and dried. Composition γ-Fe ₂ O ₃ magnetic powder 45 parts by weight VAGH (vinyl chloride-vinyl acetate copolymer manufactured by UCC) 17 parts by weight N1432J (acrylonitrile-putadiene copolymer manufactured by Nippon Zeon) 3.5 parts Coronate L (Japan Polyisocyanate manufactured by Polyurethane Co., Ltd.) 1.5 parts by weight Methyl isobutyl ketone 50 parts by weight Toluene 50 parts by weight Carbon black 4 parts by weight Thereafter, it was passed between smooth pressure rolls, calendered, and cured at 70°C for 24 hours. Next, a central hole and index hole were punched out onto an 8-inch diameter disk, polished while rotating to a mirror finish, and inserted into the jacket of a commercially available 8-inch floppy disk to create a floppy disk. (Let's call it disk A). On the other hand, for comparison, the characteristics are shown in Table 3 in comparison with a commercially available floppy disk (disk B) whose base film is polyethylene terephthalate film.

[Table] Here, Rd and Rs were measured using the following method. Evaluation of recording and playback characteristics of floppy disks A commercially available 8-inch floppy disk drive (48 tracks/inch, track width approximately 320 μm) was modified, and only the head and drive sections were placed in a constant temperature and humidity chamber, and the control circuit, etc. The test was carried out using an external test device. Test R Positional stability of the track against changes in temperature and humidity The floppy disk to be tested was set in the drive section of the test equipment described above, and the test was carried out for 12 hours at 10℃ and 8%RH.
After leaving it for a while, record a 125KHz sine wave signal on the outermost track (track 00) under the same conditions.
Let R ₀ be the average signal amplitude when immediately reproduced. After that, change the atmosphere to 51.7℃ and 80%RH for 12
Let _R1 be the average signal amplitude when the outermost track is reproduced under the same conditions after a certain period of time. Let Rd=R ₁ /R ₀ be an index of the positional stability of the truck against changes in temperature and humidity (needless to say, if Rd is 1
The closer it is, the better). Test B Permanent deformation under high temperature and high humidity The floppy disk to be tested was set in the above test equipment and left at 23℃ and 50% RH for 24 hours.
Let S ₀ be the average signal amplitude when a sine wave signal of is recorded and immediately played back. Next, the atmosphere was changed to 70°C and 90% RH, held for 2 hours, returned to 23°C and 50% RH, and held for 24 hours. Thereafter, the average signal amplitude when the outermost track is reproduced under the same conditions is set as _S1 . Sd=S ₁ /S ₀ is used as an index of permanent deformation characteristics under high temperature and high humidity. (The closer Sd is to 1, the better). Judging from the above results, it can be seen that the film of the present invention is also excellent for ordinary floppy disk applications. Example 4, Comparative Example 4 One side of the film used in Example 3 was subjected to corona discharge treatment in air to increase the surface tension to 50 dyn/cm. Subsequently, a target consisting of 80% by weight Co and 20% by weight Ni was prepared, and using this target, a Co--Ni magnetic thin film with a thickness of about 3000 Å was formed on the corona-treated surface by RF sputtering. At this time, the distance between the target and the film is 60mm, the plate voltage is 2KV, and the plate current is
The temperature was 150mA and the argon pressure was 1.2×10 ^-1 mmHg. Next, this was punched into a disk having an outer diameter of the standard 5.25-inch mini floppy disk, and a central hole of the same standard was punched out to create a magnetic disk. (Disk C) On the other hand, for comparison, a disk was made from polyethylene terephthalate film. (Disk D) The characteristics are shown in Table 4.

〔Effect of the invention〕

As described above, the film of the present invention is particularly excellent as a film for electrical insulation materials and for use in printed wiring boards, and is also useful for various uses including ordinary floppy disks.

Claims (1)

[Claims] 1. Laminated on both sides of a biaxially oriented polyester film are layers consisting of a biaxially oriented polyphenylene sulfide film in which 70 mol% or more of the repeating units are represented by the following structural formula (). A composite film characterized by: