JPH022409B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing poly p-phenylene sulfide film having excellent dimensional stability. Conventionally, polyethylene terephthalate (hereinafter referred to as
PET (abbreviated as PET) film takes advantage of its mechanical properties, dimensional stability, electrical properties, transparency, and chemical resistance to be used as insulation film, base film for magnetic tape, photographic base film, packaging film, etc. Used in various fields. but,
The disadvantage of PET film is its heat resistance, and even the heat-resistant type can only be used continuously at a temperature of 130°C.
Polyimide film is currently available as a heat-resistant film, and taking advantage of its excellent heat resistance,
It is used as a space and aircraft material and as a high-grade electrical insulation material. Due to the importance of energy conservation and demands for smaller, lighter weight, higher performance, and improved reliability of various industrial equipment, their applications and usage are expanding year by year. However, since this polyimide film is produced by a solution casting method, it has the drawbacks of poor productivity and high cost. Therefore, as a film that has better heat resistance than PET film and can be melt-molded and has good productivity, polyp
- Phenylene sulfide film is known. Biaxially stretched poly p-phenylene sulfide film is disclosed in JP-A No. 56-62128, etc., where an unstretched sheet or film of almost amorphous poly p-phenylene sulfide is ~
It is obtained by stretching in one or two directions at a temperature of 120°C and heat-setting at a temperature that does not exceed the Tm (melting point) of the stretched film. In this manufacturing process, the heat setting temperature is Tm
carried out at temperatures below. In other words, the heat fixation temperature is
The temperature is 150-280℃. However, when poly p-phenylene sulfide film is heat-set in such a temperature range, the heat shrinkage rate at 200°C is about 1.0%, as seen in JP-A-56-62121. The drawback was poor dimensional stability under heating. The inventors of the present invention focused on this point, and as a result of intensive research into a new heat-setting method, they discovered that by heat-setting within a specific temperature range, a film with good dimensional stability under heating can be obtained in a short time. , the present invention has been achieved. That is, the present invention provides a poly p-phenylene sulfide film, which is characterized by heat-setting a biaxially stretched poly p-phenylene sulfide film stretched and oriented in both the longitudinal and lateral directions at a temperature range of Tm to 350°C. The present invention relates to a method for producing an id film. The poly p-phenylene sulfide of the present invention is
More than 90 mol% is a constituent unit

A polymer consisting of the formula is preferred; if the amount is less than 90 mol%, not only will crystallinity decrease, heat resistance and mechanical properties deteriorate, but also dimensional stability will be adversely affected. If the poly p-phenylene sulfide is less than 10 mol %, it may form a meta bond, for example.

[Formula] Ether bond

[Formula] Biphenyl linkage If

[Formula] Naphthalene bond

[Formula] Sulfone bond

[Formula] Substituted Feni Rensulfide bond

[Formula] where R is alkyl, nitro, phenyl, alkoxy, sulfone, halogen, carboxylic acid, metal salt of carboxylic acid, etc.), and the aforementioned trifunctional phenylene sulfide bond.

[Formula] etc. may be included. Such poly p-phenylene sulfide is formed into a sheet or film using an extruder, press, etc., and then rapidly cooled using liquid nitrogen, water, a roll, etc. to a density of 1.330 g/cm ³ As a result, an almost amorphous unstretched film is obtained. When the crystallization of the unstretched film progresses, the crystal particles reduce the stretchability and the film becomes more likely to break during stretching. Although the stretching temperature of the unstretched film varies somewhat depending on the molecular weight and components of the polymer, it is usually desirable to draw the unstretched film around the glass transition temperature of the polymer. in particular
The temperature is 80-120°C, preferably 90-110°C. As the stretching method, commonly used stretching methods such as a roll method, a tenter method, and a tubular method are convenient. The stretching ratio is preferably 2.5 to 7.0 times, preferably 3.0 to 5.5 times, in view of the physical properties and productivity of the resulting film, and either simultaneous biaxial stretching or sequential biaxial stretching may be used. In order to increase the crystallinity of the biaxially stretched film obtained in this way without losing its transparency,
Heat treatment is carried out at a temperature range of Tm to 350°C, preferably Tm to 330°C, usually for a time of 120 seconds or less. Here, Tm is the melting point of the film immediately after biaxial stretching and before heat treatment, as measured by a differential scanning calorimeter (hereinafter referred to as DSC). At this time, if the heat treatment temperature exceeds 350°C, the film will become molten even if the heat treatment time is shortened, and the film will not be able to maintain its shape. If the heat treatment temperature is Tm~350℃
By appropriately adjusting the heat treatment time within 120 seconds, the film can be heat-set without becoming molten.
Moreover, the density increases and the dimensional stability under heating is improved compared to when heat setting is performed at a temperature below Tm. In addition, during this heat setting, it is permissible to heat set with appropriate limited shrinkage in the longitudinal and lateral directions, or under constant length or tension. in general,
The heat setting temperature of crystalline polymer films, typified by PET films, is below the melting point of the polymer. Heat setting at a temperature higher than the melting point of the polymer as in the present invention is a completely new heat setting method. Heat setting in the present invention is carried out by bringing the stretched film before heat setting into contact with a stream of heated gas or liquid or the surface of a solid. It is also possible to use radiant heat such as an infrared heater. Furthermore, ultrasonic waves or high frequency waves may be irradiated. In the present invention, the "temperature" and "time" of heat setting refer to the temperature of the heating medium and the contact time of the stretched film to the heating medium when a medium is used. Also, in the case of using an infrared heater, ultrasonic wave, high frequency, etc., it refers to the film temperature and processing time. The film of the present invention thus obtained has a high degree of crystallinity, excellent dimensional stability under heating, and does not cause whitening or embrittlement even when heated to near the melting point. The film of the present invention has excellent heat resistance, dimensional stability, and mechanical properties, and is therefore most suitable as an electrically insulating film or a magnetic recording film. For example, as a base film for flexible printed wiring boards, as an insulating material for various rotating machines and stationary devices such as vehicle motors and refrigerator motors, as an insulating material for covering general cables, high voltage and ultra-high voltage cables, and for magnetic tape. Useful as base film and capacitor film. In addition, it can be used as a film material for packaging, agriculture, photography, adhesive tape bases, building materials, decorations, etc. Also lamination with other films,
It is also possible to use it as a composite material by combining it with metal, paper, etc. Glass transition temperature, Tm, density in the present invention,
The method for measuring crystallinity will be described. The glass transition temperature is measured by a conventional method using DSC using an unstretched amorphous film or sheet before stretching, and Tm using a film immediately after biaxial stretching as measurement samples. Density is determined using a density gradient tube using an aqueous lithium bromide solution. Crystallinity (Xc) is determined by the density method using the density described above. i.e.
Xc is obtained from the following commonly used formula. 1/d=Xc/dcr+1-Xc/dam (1) In equation (1), d, dcr, and dam are the density of the sample, the density of the crystalline phase, and the density of the amorphous phase, respectively. Here dcr, dam is Eur, poly.J., 7,
1127 (1971) was used. That is, dcr=1.430g/cm ³ and dam=1.320g/cm ³ . Examples 1-3, Comparative Examples 1-3 1.8Kg of N-methylpyrrolidone and sodium sulfide (59.6% purity) in a 5 scale autoclave
0.5 kg of sodium benzoate, 0.6 kg of sodium benzoate, and 1.6 g of sodium hydroxide were charged, and the temperature was raised to 200° C. in a nitrogen gas flow, and dehydration was performed to a dehydration rate of 53%. System at 160℃
After cooling, 0.6 kg of p-dichlorobenzene was charged and sealed, and the internal pressure was increased to 4 kg/cm ³ with nitrogen. The rate of temperature increase due to the heat generated by polymerization was controlled, the temperature was raised to 250°C, and polymerization was carried out while stirring for 3 hours. Next, after cooling the system, the pressure was released, the contents were poured into water, and the powdered polymer was taken out.
Washing was repeated with water and acetone. This polymer was dried at 120°C for 3 hours to obtain a white powder polymer. The solution viscosity [η] of this polymer was determined using α-chlornaphthalene at a temperature of 206℃ and a concentration of 0.4Kg/
When measured in 100 ml, it was 0.30 dl/g. This polymer was formed into a film by pressing at 320° C. and then rapidly cooled in water to obtain a transparent, almost amorphous, unstretched sheet having a density of 1.321 g/cm ³ and a thickness of 405 microns. The glass transition temperature of this amorphous sheet was measured by DSC at a heating rate of 20°C/min and found to be 89°C. This amorphous sheet was subjected to simultaneous biaxial stretching of 3.5×3.5 times at 94°C. The Tm of this stretched film was 284°C as measured by DSC at a heating rate of 20°C/min. This film was heat-set at a fixed length at the temperature and time shown in Table 1. As a comparative example
Heat setting was carried out in the same manner as in the examples below Tm. The density, crystallinity and heat shrinkage of these films were measured and the results are shown in Table 1. The film of the present invention is characterized by high density and crystallinity, low thermal shrinkage rate, and excellent dimensional stability under heating. Examples 4 to 6, Comparative Examples 4 to 7 The amorphous sheets used in Examples 1 to 3 were vertically heated at 95°C.
Successive biaxial stretching of 3.5×4.0 times in width was performed, and Example 1~
When Tm was measured in the same manner as in 3, it was 286°C.
This film was heat-set under constant length at the temperature and time shown in Table 2. As a comparative example, Tm
Heat setting was carried out in the same manner as in the examples. The density, crystallinity, and heat shrinkage rate of these films were measured,
The results are shown in Table-2. The film according to the present invention has good dimensional stability under heating.

【table】

[Table] The heat shrinkage rate in Table-1 and Table-2 is width 10
A film with a length of 150 mm and marked lines at 100 mm intervals in the length direction was left in a dryer at each temperature shown in the table in a relaxed state for 30 minutes, then the film was removed from the dryer and marked with marks. The line spacing was measured and the shrinkage rate at that time was determined.

Claims (1)

[Claims] 1. A polyp characterized by heat-setting a biaxially oriented polyphenylene sulfide film stretched and oriented in both the vertical and horizontal directions at a temperature range of Tm (Tm: melting point of the film immediately after biaxial stretching) to 350°C. -Production method of phenylene sulfide film.