JPH022410B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a poly p-phenylene sulfide film, and particularly to a method for producing a poly p-phenylene sulfide film that has a high degree of crystallinity and a low thermal shrinkage rate. 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. It is used in various fields. However, PET film has a drawback in its heat resistance, and its continuous use temperature is only 130℃ for heat-resistant types. Polyimide films are on the market as films with excellent heat resistance, and due to their excellent heat resistance, they are used as materials for space and aircraft and as high-grade electrical insulation films. Due to the importance of energy conservation and demands for smaller size, lighter weight, and higher performance of various industrial machines, 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, poly p-phenylene sulfide film has been proposed as a film which has better heat resistance than PET film and can be melt-molded and has good productivity, as seen in Japanese Patent Application Laid-open No. 142275-1983. This poly p-phenylene sulfide film is superior to PET film in chemical resistance and heat resistance, and also has good mechanical properties, making it a film with well-balanced physical properties. However, polyp-
Because phenylene sulfide has a slow crystallization rate, it has the drawbacks of low crystallinity and high heat shrinkage when heat-fixed below Tm, which is usually done. It was necessary to perform heat fixation, which was disadvantageous for continuous production. The inventors of the present invention focused on this point, and as a result of intensive research, we found that by heat treatment under specific conditions, the degree of crystallinity is high and the thermal shrinkage rate is low, and even once the film is heated to around Tm, the physical properties decrease. The present invention was achieved by discovering that a film with a small amount of heat can be obtained by heat treatment for a short time. That is, in the present invention, a biaxially stretched poly p-phenylene sulfide film that has been stretched and oriented in two directions (vertical and horizontal) is first heat treated under tension at a temperature range of Tm to 350°C, and then heat treated at a temperature of 150 to 350°C. The present invention provides a method for producing a poly p-phenylene sulfide film, which is characterized by heat treatment under limited shrinkage or elongation or constant length within a temperature range of 25% in one or both directions. The poly p-phenylene sulfide of the present invention is
More than 90 mol% is a constituent unit

Preferably a polymer consisting of [Formula], 90 mol%
If the amount is less than this, not only will crystallinity deteriorate, heat resistance and mechanical properties will 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. After forming such polyp-phenylene sulfide into a sheet or film using an extruder, press, etc., the density is reduced to 1.330 g/cm ³ by rapidly cooling it using liquid nitrogen, water, a roll, etc. As a result, an almost amorphous unstretched film is obtained. If the crystallization of the unstretched film progresses, the stretchability will decrease and the film will be 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. The biaxially stretched film obtained in this way has an increased degree of crystallinity without losing its transparency.
Heat treatment is carried out under tension at a temperature range of Tm to 350°C, preferably Tm to 330°C, usually for a time of up to 120 seconds. Here, Tm is the melting point obtained by a differential scanning calorimeter (hereinafter abbreviated as DSC) of the film immediately after biaxial stretching. At this time, if the heat treatment temperature exceeds 350°C, the film becomes molten even if the heat treatment time is shortened, and the film cannot maintain its shape. By appropriately adjusting the heat treatment time, within 120 seconds if the heat treatment temperature is Tm ~ 350℃,
The film can be heat-set without becoming molten. Films that have been heat-set in this way may show a large value when the heat shrinkage rate is measured, for example, by gradually increasing the temperature from room temperature or by directly contacting a high-temperature atmosphere. In some cases, it may not be desirable as a material to be used. However, the film after heat setting like this is 150
within 25% in one or both directions within a temperature range of ℃ to 350℃, preferably 200℃ to 330℃, preferably
Limited contraction or elongation within 15% or under constant length
By heating appropriately within 10 minutes, the thermal shrinkage rate can be reduced and the dimensional stability under heating can be improved. 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 350° C. or less, the heat treatment can be carried out by appropriately adjusting the heat treatment time within 10 minutes. At this time, if heat treatment is performed in a state that causes shrinkage of 25% or more, the flatness of the film will deteriorate. Furthermore, heat treatment under elongation of 25% or more increases the thermal shrinkage rate of the resulting film. The film heat-treated in this manner may be further heat-treated at 150 to 350° C. for a fixed length, if necessary. The heat treatment in the present invention is carried out by bringing the film before heat treatment into contact with a heated gas, liquid or solid. It is also possible to use radiation such as an infrared heater, ultrasonic waves, or high frequency irradiation. In the present invention, the "temperature" and "time" of heat treatment refer to the temperature of the heating medium and the contact time with the heating medium in the case of using a medium, and in the case of using an infrared heater, ultrasonic wave, or high frequency, film temperature and processing time. The film of the present invention obtained in this way has a high degree of crystallinity, has excellent dimensional stability under heating, does not cause whitening or embrittlement even when heated to around Tm, and does not easily deteriorate in physical properties. . The film of the present invention has excellent heat resistance, dimensional stability, and mechanical properties, and is therefore suitable as an electrically insulating film and a magnetic recording film. For example, as a base film for flexible printed wiring boards, insulating materials for various rotating machines such as vehicle motors and refrigerator motors, and various stationary devices, insulating materials for covering general cables, high voltage, and ultra-high voltage cables, and for magnetic tables. 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. It can also be used as a composite material by laminating it with other films, or by combining it with metals, paper, etc. The types of physical properties and their measurement methods in the present invention will be described. (1) Glass Transition Temperature and Tm The glass transition temperature was measured using DSC using an unstretched amorphous film or sheet before stretching, and the Tm was measured using a film immediately after biaxial stretching, using DSC as measurement samples. (2) Density and crystallinity (Xc) Density was determined using a density gradient tube using an aqueous lithium bromide solution. Crystallinity (Xc) was determined by the density method using the density described above. i.e.
Xc is generally determined by the following equation (1). 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 and dam used the values found in Eur. Poly. J., 7, 1127 (1971). That is, dcr=
1430g/cm ³ , dam=1320g/cm ³ . (3) Heat shrinkage rate The heat shrinkage rate is determined by cutting the heat-set film into a piece of 5mm wide and 100mm long, marking it with a 50mm mark, and keeping it in a relaxed state for 10 minutes in a dryer kept at a specified temperature. It was determined by measuring the distance between the gauge lines on the film. (4) Tensile test For the tensile test sample, the film after heat setting was cut into 5 mm width and 100 to 150 mm length, and the film was heat-treated in a relaxed state for 10 minutes in a dryer kept at a specified temperature. The breaking strength (tensile strength), elongation, and F-5 value retention of the film before the heat treatment were determined. The tensile test was carried out using a Tensilon tensile testing machine, where the sample was held with a grip to a sample length of 50 mm and stretched at a tensile rate of 200%/min. At this time, the temperature of the sample was kept at 23°C. ◎ F5 value This is the tensile stress when the elongation of the film is 5% in a tensile test. (5) Relaxation rate This is expressed as the degree of shrinkage of the film during the second heat setting. Examples 1 to 6, Comparative Examples 1 to 3 5 N-methylpyrrolidone in an autoclave
1.8Kg of sodium sulfide heptahydrate, 0.5Kg of sodium sulfide hexahydrate, 0.6Kg of sodium benzoate, and 1.6g of sodium hydroxide were charged, and the temperature was gradually raised to 200℃ under a nitrogen atmosphere with stirring for about 2 hours, and 105ml of water was added. I distilled it out. After cooling the reaction system to 170°C, 0.6 kg of p-dichlorobenzene and 0.4 kg of N-methylpyrrolidone were added, and the mixture was reacted at 220°C for 2 hours and then at 250°C for 3 hours. The internal pressure at the end of polymerization was 6.7 Kg/cm ² .
After cooling the reaction system, the contents were separated, and the resulting solid content was washed three times with hot water and further twice with acetone, and then dried at 120° C. for 3 hours to obtain a grayish-white granular polymer. The intrinsic viscosity [η] of this polymer was determined using α-chlornaphthalene at a temperature of 206℃ and a concentration of
When measured at 0.4g/100ml, it was 0.31. This polymer was press-formed at 310°C and then rapidly cooled in water to obtain a transparent unstretched sheet with a thickness of 400 μm. This sheet had a density of 1321 g/cm ³ and was almost amorphous. The sheet glass transition temperature was measured using DSC at a heating rate of 10°C/min and found to be 89°C. 95% of this amorphous unstretched sheet
Simultaneous biaxial stretching of 3.5 x 3.5 times was carried out at °C. The Tm of this film was measured by DSC at a heating rate of 10°C/min and was found to be 287°C. This film table-1
Heat fixation was carried out under various conditions as shown below, and various physical properties were measured. As shown in Table 1, the film of the present invention had a small thermal shrinkage rate, showed little deterioration in physical properties even when heated to around Tm, and was found to have good heat resistance.

[Table] (Note) The second heat setting in Example 6 was an elongation of 5%.
Example 7, Comparative Example 4 585 g of p-dichlorobenzene as a monomer,
Polymerization was carried out under the same conditions as in Examples 1 to 3, except that 2.2 g of 1,2,4-trichlorobenzene was used.
A gray-white, granular polymer was obtained. The intrinsic viscosity [η] of this polymer was measured under the same conditions as in Examples 1 to 3 and was found to be 0.45. This polymer was formed into a film by pressing at a pressure of 310 mm and then rapidly cooled in water to obtain a transparent unstretched sheet with a thickness of 400 μm.
This sheet had a density of 1322 g/cm ³ and was almost amorphous. The glass transition temperature of this sheet was measured in the same manner as in Examples 1 to 3 and was found to be 90°C. This amorphous unstretched sheet was sequentially biaxially stretched 3.5 times (MD) x 4.0 times (TD) at 95°C.
The Tm of this film was measured in the same manner as in Examples 1 to 3 and was found to be 281°C. This film was heat-set under tension at 300°C for 20 seconds, and then subjected to a 5% relaxation treatment at 250°C for 15 seconds. As a comparative example, after heat setting under tension at 250°C for 20 seconds, a 5% relaxation treatment was performed at the same temperature for 15 seconds. The physical properties of these films were set in the same manner as in Examples 1 to 3, and are shown in Table 2. Table-2
As shown in Figure 2, it was found that the film of the invention had a small thermal shrinkage rate and good heat resistance.

【table】

[Table] A cut out film was used.

Claims (1)

[Claims] 1 First, a biaxially stretched polyP-phenylene sulfide film that has been stretched and oriented in two directions (vertical and horizontal) is
Heat treated under tension in the temperature range of Tm℃ (Tm: melting point of the film measured by differential scanning calorimeter) ~ 350, then limited shrinkage within 25% in one or two directions in the temperature range of 150 to 350. Or poly p- characterized by being heat treated under elongation or constant length.
Method for producing phenylene sulfide film.