JP5069545B2 - Process for producing heat-treated poly-p-phenylene sulfide film - Google Patents

Description

  The present invention relates to a method for producing a heat-treated poly-p-phenylene sulfide film and a heat-treated poly-p-phenylene sulfide film obtainable thereby. Hereinafter, poly-p-phenylene sulfide is referred to as “PPS”.

In the field of electrical and electronic parts, there is an increasing demand for an insulating base material having excellent electrical characteristics and heat resistance from the viewpoint of miniaturization and high functionality of equipment.
A biaxially stretched PPS film (biaxially stretched PPS film) has excellent electrical properties and mechanical properties, excellent heat resistance, low water absorption, and high chemical resistance. However, since a dimensional change due to thermal contraction occurs, for example, when used for a circuit board, there is a problem that the circuit is liable to be displaced when heat is applied. Moreover, when it was used as a spacer at the time of manufacture of various flexible substrates, there was a problem that the substrate was easily deformed due to the shrinkage of the biaxially stretched PPS film. Here, the dimensional stability refers to the ability to maintain the dimensions even when the ambient conditions such as temperature vary.

  In Patent Document 1, a biaxially stretched PPS film is heat-treated at 150 to 280 ° C. under tension, and then is less than the heat treatment temperature at 50 ° C. or more, both within the longitudinal and lateral directions, under limited shrinkage or extension or constant length of 20% or less. A method for improving the dimensional stability by heat-treating again at the temperature is disclosed.

Further, Patent Document 2 states that when the processing for reducing the thermal shrinkage rate of the biaxially stretched PPS film is performed by annealing or the like, the flatness of the film may be remarkably deteriorated.
Japanese Patent Publication No.59-5099 JP 2004-96040 A

  With the expansion of the application field of PPS films, further improvement in the dimensional stability of biaxially stretched PPS films is desired. Accordingly, an object of the present invention is to provide a production method capable of producing a heat-treated PPS film that not only has high flatness but also exhibits excellent dimensional stability, and flatness and dimensional stability that can be obtained by this production method. The object is to provide a heat-treated PPS film having high properties.

  The present invention is a method for producing a heat-treated PPS film including a heating step for heating a biaxially stretched PPS film, wherein the heating step is performed at a heating temperature selected from a range of more than 160 ° C. and less than 290 ° C. Provided is a production method in which a tensile stress smaller than a shrinkage stress at a heating temperature of an axially stretched PPS film is applied to the biaxially stretched PPS film in one direction.

  In the production method of the present invention, the biaxially stretched PPS film is heated at a predetermined temperature of more than 160 ° C. and less than 290 ° C., and a tensile stress smaller than the shrinkage stress of the biaxially stretched PPS film at that temperature is applied in one direction. The main feature is that it is added, and by performing the heat treatment under such conditions, it becomes possible to produce a heat-treated PPS film having high flatness and excellent dimensional stability.

  In the heating step, it is preferable to perform heating continuously while winding the biaxially stretched PPS film. At this time, it is preferable to apply a tensile stress smaller than the shrinkage stress to the biaxially stretched PPS film in the winding direction. By continuously heating while winding the biaxially stretched PPS film, a heat-treated PPS film having particularly excellent flatness and dimensional stability can be obtained continuously, which is industrially advantageous.

  In this case, the tensile stress smaller than the shrinkage stress applied to the biaxially stretched PPS film is equivalent to a film having a cross-sectional area of 1 m width and 40 μm thickness, and is preferably more than 0 kgf and less than 20 kgf. When a tensile stress in the above range is applied at a heating temperature of more than 160 ° C. and less than 290 ° C., a heat treated PPS film having high planarity and further improved dimensional stability can be obtained efficiently. The numerical values of the above tensile stress are values in the case of a film having a cross-sectional area of 1 m width and 40 μm thickness. For films having different cross-sectional shapes, the tensile stress is converted into strength at the time of a cross-sectional area of 1 m width and 40 μm thickness. To evaluate.

  A heat-treated PPS film can be obtained by the above-described production method. This heat-treated PPS film has high flatness and excellent dimensional stability. For example, dimensions such as a precision electronic circuit board and a spacer (peeling film) at the time of production of the board are available. It can be suitably used for applications in which a deviation is not allowed.

  The present invention provides a method for producing a heat-treated PPS film having high flatness and exhibiting very excellent dimensional stability. Moreover, the heat processing PPS film obtained by this manufacturing method and having high flatness and dimensional stability is provided.

  The method for producing a heat-treated PPS film of the present invention includes a heating step of heating the biaxially stretched PPS film. In this heating step, the heating is performed at a heating temperature selected from the range of more than 160 ° C. and less than 290 ° C., and a tensile stress smaller than the shrinkage stress of the biaxially stretched PPS film at this temperature is taken up of the biaxially stretched PPS film. Append to direction.

  A heating process can be implemented by hold | maintaining a biaxially-stretched PPS film in furnaces (drying furnace etc.) set to the temperature (T1) chosen from the range over 160 degreeC and less than 290 degreeC, for example. In this case, the temperature of the drying furnace may be made uniform so as to be T1 as a whole, and within the above range, but different from T1, T2, T3, T4. The biaxially stretched PPS film may be exposed to these temperature ranges. Furthermore, you may make it change the temperature of a drying furnace gradually from T1 to T2. When the heating temperature is 160 ° C. or lower, the improvement in the dimensional stability of the biaxially stretched PPS film may be insufficient, and when the heating temperature is 290 ° C. or higher, the biaxially stretched PPS film melts and it is difficult to maintain the film shape. . The heating temperature is preferably more than 160 ° C and less than 290 ° C, more preferably more than 160 ° C and less than 285 ° C, even more preferably more than 160 ° C and less than 260 ° C, even more preferably more than 160 ° C and less than 250 ° C, more preferably more than 180 ° C and more than 250 ° C. Is even more preferable, and more than 180 ° C. and less than 240 ° C. is particularly preferable.

In the heating step, it is preferable to heat so that the entire biaxially stretched PPS film reaches the heating temperature uniformly. Therefore, it is preferable to control the moving speed and heating time in the drying furnace according to the thickness and width of the biaxially stretched PPS film. As described below, when the biaxially stretched PPS film is continuously heated in the drying furnace, the thickness direction may reach the heating temperature uniformly until it is pulled out from the drying furnace. . If the heating time is too short, the dimensional stability of the biaxially stretched PPS film cannot be sufficiently improved, and if it is too long, the amount of shrinkage increases and becomes non-uniform, resulting in poor flatness.
For example, when a biaxially stretched PPS film having a width of 1 m and a thickness of 40 μm is heated by moving at a speed of 20 m / min in a drying furnace, the residence time of the biaxially stretched PPS film in the drying furnace is 15 seconds to 2 minutes is recommended. For example, when a biaxially stretched PPS film having a width of 1 m and a thickness of 25 μm is heated by moving at a rate of 40 m / min in a drying furnace, the residence time of the biaxially stretched PPS film in the drying furnace is set to 15 It may be a second to 1 minute.

  In the heating process, it is preferable to install a winder on the outlet side of the drying furnace and continuously perform the heating process while winding the biaxially stretched PPS film. In this process, the tensile stress that the biaxially stretched PPS film is subjected to in the winding direction is equivalent to a film having a cross-sectional area of 1 m width and 40 μm thickness, which is greater than 0 kgf and from the shrinkage stress of the biaxially stretched PPS film at the temperature of the heating process It is important to keep it small. This tensile stress is equivalent to a film having a cross-sectional area of 1 m width and 40 μm thickness, preferably more than 0 kgf and less than 20 kgf, more preferably more than 0 kgf and less than 5 kgf, more preferably more than 0 kgf and less than 2 kgf. It is particularly preferable that it is more than 0 kgf and less than 1 kgf. By this manufacturing method, it is possible to maintain the flatness of the heat-treated PPS film and dramatically improve the dimensional stability.

  The shrinkage stress of the biaxially stretched PPS film at a certain temperature is, for example, from 30 ° C. at a heating rate of 10 ° C./min using a thermal analyzer (TMA) (manufactured by SII, model TMA / SS6100, standard type). It can be measured by raising the temperature to 345 ° C. Table 1 shows the measured values of the shrinkage stress of the biaxially stretched PPS film at each temperature, measured by the above method. A 40 μm thick biaxially stretched PPS film was used as the sample, the sample length was kept constant at 15 mm, and the relationship between temperature and shrinkage stress was determined from the change in load during the temperature rising process. The biaxially stretched PPS film used for this measurement is a polymer containing 70 mol% or more of poly-p-phenylene sulfide which is a repeating unit, and has a weight average molecular weight (Mw) of about 50,000 and 310 ° C. The melt viscosity of was 1580 poise under conditions of a shear rate of 1,200 / sec. As a monomer for obtaining the biaxially stretched PPS film used for the measurement, sodium hydrosulfide and sodium hydroxide were used. The shrinkage stress in Table 1 is shown as the stress per 1 m width of a 40 μm thick biaxially stretched PPS film.

  From Table 1, in the manufacturing method of the heat-treated PPS film of the present invention, for example, when the heating step is performed at 200 ° C., the tensile stress that the biaxially stretched PPS film receives in the winding direction is 1 m wide and 40 μm thick in cross-sectional area. It can be seen that the film should be adjusted to be larger than 0 kgf and smaller than 0.51 kgf.

  By the above production method, it is possible to produce a heat-treated PPS film having high planarity and showing very excellent dimensional stability.

Subsequently, a biaxially stretched PPS film that can be used in the production method of the present invention will be described.
The PPS polymer that is a material of the biaxially stretched PPS film is a polymer in which 70 mol% or more, preferably 90 mol% or more in the polymer composition is composed of structural units represented by the following structural formula (1). If this component is less than 70 mol%, the crystallinity, thermal transition temperature, etc. of the polymer will be low, and it may not be possible to fully exhibit the heat resistance, mechanical properties, etc., which are the characteristics of films mainly composed of PPS. .

As long as it is less than 30 mol%, preferably less than 15 mol% of the constituent units of the polymer, units other than the above structural formula (1) containing a copolymerizable sulfide bond may be contained. Specific examples of the unit containing a copolymerizable sulfide bond include those composed of a structural unit represented by the following structural formula (2), and one or more of them may coexist. In Structural Formula (2), Q represents a halogen atom or a methyl group, and m represents an integer of 1 to 4.

  When the PPS polymer contains the structural unit represented by the structural formula (2), the polymer structural unit may be polymerized in any form of random copolymerization and block copolymerization. Further, a structural unit other than the structural formula (1) may be present at or near the terminal of the polymer. The remaining less than 30 mol% of the polymer may contain additives other than the PPS polymer, such as a polymer, a colorant, and an ultraviolet absorber.

A biaxially stretched PPS film can be produced by, for example, obtaining an unstretched film by the following method and then stretching it biaxially.
First, the resin composition which has PPS as a main component is supplied to an extruder, and is made into the form of a pellet. The melt viscosity of PPS in the present invention is preferably 200 poise or more under conditions of 310 ° C. and a shear rate of 1200 / sec. Here, the shear rate is a value defined as a velocity gradient when a viscous fluid passes between parallel plates. In the present invention, the melt viscosity of PPS under these conditions is preferably in the range of 200 to 20,000 poise, and more preferably in the range of 300 to 18,000 poise. When the melt viscosity is less than 200 poise, the mechanical properties and heat resistance of the film are inferior, and the characteristics of the PPS film may not be exhibited. On the other hand, when the melt viscosity is 20,000 poises or more, a high load may be applied to the extruder or the filtering device, which may be a problem. In this process, the resin composition containing PPS as a main component can be cast into a film by connecting a molding die directly to the outlet of the extruder without forming a pellet.

Subsequently, the resin pellets mainly composed of PPS obtained in the above process are supplied to an extruder. The supplied resin is melted by heat, formed into a desired film shape with a die, and discharged. In this process, it is preferable to obtain a good PPS film by filtering molten resin through a filter or the like to remove coarse foreign matters such as dust or aggregates of additives.
An unstretched film is obtained by pressing the film discharged from the die onto a cooling body such as a metal drum and solidifying by cooling.

  The unstretched film thus obtained is imparted with strength by biaxial stretching. Biaxial stretching refers to stretching in order to give molecular orientation in the longitudinal and transverse directions. Here, the longitudinal direction refers to the longitudinal direction (winding direction) of the film, and the lateral direction refers to the width direction of the film. Stretching may be sequentially biaxially stretched or simultaneously stretched in two directions. Further, re-stretching may be performed in the longitudinal and / or transverse direction.

  Here, the case of sequential biaxial stretching will be described. First, stretching in the machine direction is performed by stretching between rolls, and then stretching in the transverse direction is performed using a tenter stretching machine.

  First, stretching in the longitudinal direction will be described. Stretching in the longitudinal direction is usually performed by the difference in the peripheral speed of the roll. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs.

  80-110 degreeC is preferable and, as for the surface temperature of the PPS film at the time of extending | stretching to a vertical direction, 85-105 degreeC is more preferable. When the stretching temperature is 80 ° C. or lower, the stretching stress becomes high and the film may be whitened. On the other hand, when the stretching temperature is 105 ° C. or higher, stick slip occurs where the film intermittently adheres to the stretching roll, and uniform stretching becomes difficult. The stretching temperature is usually set by adjusting the temperature of the roll.

  The stretching ratio in the longitudinal direction is preferably 2.6 to 5.0 times, and more preferably 3.0 to 4.0 times. When the stretching ratio is 2.6 times or less, it is difficult to obtain sufficient strength and heat resistance in the longitudinal direction. In addition, when the draw ratio is 5.0 times or more, the drawable ratio in the transverse direction is low, and it is difficult to draw in the transverse direction at a sufficient magnification, making it difficult to balance the physical properties in the longitudinal and transverse directions. It becomes.

  The stretching speed in the machine direction is preferably 100 to 50,000% / min, more preferably 200 to 40,000% / min. When the stretching speed is 100% / min or less, the productivity tends to deteriorate. When the stretching speed is 50,000% / min or more, the heat treatment time in the tenter stretching machine is shortened, and a biaxially stretched PPS film having excellent dimensional stability may not be obtained.

  Next, the stretching in the lateral direction will be described. The PPS film stretched in the longitudinal direction is introduced into a tenter stretching machine, and both ends of the PPS film are gripped and pulled by clips of the tenter stretching machine to perform stretching in the lateral direction.

  The temperature of the PPS film during stretching in the transverse direction is preferably 80 to 110 ° C, and more preferably 85 to 105 ° C. When the stretching temperature is 80 ° C. or less, stretching may not be performed uniformly and good surface properties may not be obtained. Further, when the stretching temperature is 110 ° C. or higher, oriented crystallization does not proceed sufficiently, and the elastic modulus and heat resistance properties tend to be insufficient.

  Further, the stretching ratio in the transverse direction is preferably 2.5 to 5.0 times, and more preferably 3.0 to 4.5 times. If the draw ratio is 2.5 times or less, it is difficult to obtain a uniform draw ratio in the transverse direction, which may cause poor flatness. Moreover, when the draw ratio is 5.0 times or more, breakage frequently occurs and the productivity tends to be lacking.

  Further, the stretching speed in the transverse direction is preferably 100 to 5,000% / min, and more preferably 150 to 3,000% / min. When the stretching speed is 100% / min or less, the productivity tends to deteriorate. On the other hand, when the stretching speed is 5,000% / min or more, the heat treatment time in the tenter stretching machine is shortened, and a biaxially stretched PPS film having excellent dimensional stability may not be obtained.

  Immediately after stretching in the transverse direction, the PPS film is relaxed by reducing the distance between the clips by 0.1 to 10%, more preferably 0.5 to 7%, and heat setting at a temperature higher than the stretching temperature and lower than the melting point in the tenter stretching machine. It is preferable to carry out the treatment. By this heat setting treatment, an effect of reducing the shrinkage rate at a high temperature in the lateral direction can be obtained. The temperature of the heat setting treatment is preferably more than 240 ° C. and less than 290 ° C., more preferably more than 250 ° C. and less than 285 ° C. When the temperature of the heat setting treatment is 240 ° C. or less, the lateral relaxation due to heat setting is not efficiently performed, and it becomes difficult to obtain a biaxially stretched PPS film having excellent dimensional stability at high temperatures. Further, when the temperature of the heat setting treatment is 290 ° C. or higher, the melting point of the PPS film is exceeded, so that film formation becomes difficult.

  After the heat setting treatment, the PPS film cooled to room temperature at the exit of the tenter stretching machine is wound up by a winder to obtain a biaxially stretched PPS film. The thickness of the biaxially stretched PPS film is preferably in the range of 3 to 120 μm, and more preferably in the range of 5 to 100 μm. When the thickness is 3 μm or less, the film is easily affected by foreign substances during stretching and film formation becomes difficult. On the other hand, when the thickness is 120 μm or more, the load applied between the rolls during longitudinal stretching is high, and film formation becomes difficult.

  Subsequently, the biaxially stretched PPS film obtained by the above method is subjected to a heating step. As equipment used for the heating process, a normal roll support type coater can be used. Alternatively, a coating facility having a floating drying furnace can also be used. Moreover, since coating is not essential, a drying furnace without a coating head may be used. By providing a measuring means for measuring the tensile stress received by the film in a drying furnace, the tensile stress received by the biaxially stretched PPS film in the heating step can be measured.

  When there is a delivery part at the entrance of the drying furnace and a nip roll at the exit, the tensile stress applied to the biaxially stretched PPS film is adjusted by the braking force of the delivery part and the speed of the nip roll at the exit of the drying furnace. When the brake of the delivery part is strong, the tensile stress received by the biaxially stretched PPS film is high without depending on the nip speed at the exit of the drying furnace. On the other hand, when the brake force of the delivery part is weak, it is possible to reduce the tensile stress received by the biaxially stretched PPS film by reducing the nip roll speed. In addition, when the nip roll speed is increased, the tensile stress received by the biaxially stretched PPS film increases. In such a case, the tensile stress received by the biaxially stretched PPS film should be adjusted low by reducing the braking force. Can do.

  When nip rolls are installed at both the inlet and outlet of the drying furnace, the tensile stress applied to the biaxially stretched PPS film can be easily controlled by adjusting the speed ratio between the two. If the exit roll is faster than the entrance roll, the tensile stress experienced by the biaxially stretched PPS film will increase, and if vice versa, very weak tensile stress can be achieved.

  In the examples of the present invention, a roll support type coater was used, and the tensile stress applied to the biaxially stretched PPS film was adjusted by the brake force of the feeding section to the drying furnace and the nip roll speed at the outlet of the drying furnace. The method for controlling the tensile stress received by the biaxially stretched PPS film is not limited to this.

  The heating time is preferably 1 to 60 seconds, more preferably 2 to 30 seconds. When the time is 1 second or less, it is difficult to sufficiently relax the biaxially stretched PPS film in the longitudinal and transverse directions, and the dimensional stability at high temperatures may not be improved. Further, when the heating time is 60 seconds or more, the productivity tends to deteriorate.

The heating temperature is preferably more than 160 ° C and less than 290 ° C, more preferably more than 160 ° C and less than 285 ° C, even more preferably more than 160 ° C and less than 260 ° C, even more preferably more than 160 ° C and less than 250 ° C, more preferably more than 180 ° C and more than 250 ° C. Is even more preferable, and more than 180 ° C. and less than 240 ° C. is particularly preferable. Below 160 ° C., it is difficult to sufficiently relax in the vertical and horizontal directions, and the dimensional stability at high temperatures tends not to be improved.
Above 290 ° C, the biaxially stretched PPS film may melt. Further, since the amount of shrinkage is large and the shrinkage occurs unevenly, the flatness tends to be remarkably lowered.

  The tensile stress received by the biaxially stretched PPS film in the heating step needs to be kept lower than the shrinkage stress of the biaxially stretched PPS film at the heating temperature. The shrinkage stress of the film varies with temperature. For example, when the heating temperature is more than 160 ° C. and less than 250 ° C., the tensile stress received by the biaxially stretched PPS film is equivalent to a film having a cross-sectional area of 1 m width and 40 μm thickness, preferably more than 0 kgf and less than 5 kgf. More preferably, it is more than 0 kgf and less than 2 kgf, particularly preferably more than 0 kgf and less than 1 kgf. When the heating temperature is higher than 160 ° C and lower than 250 ° C, it is difficult to obtain a film with excellent dimensional stability when a tensile stress of 5 kgf or more is applied to a film having a cross-sectional area of 1 m wide and 40 µm thick. There are cases. In order to determine the tensile stress applied to the biaxially stretched PPS film, a numerical value representing the relationship between the temperature shown in Table 1 and the shrinkage stress of the biaxially stretched PPS film may be referred to. However, the shrinkage stress of the film is not limited to the values shown in Table 1 because it varies depending on the stretching conditions of the biaxially stretched PPS film and the tenter heat treatment conditions.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples of the present invention. However, the present invention is not limited to these examples, and various modifications can be made without departing from the technical idea of the present invention. Can be changed.

Example 1
A powder of PPS (manufactured by Kureha Co., Ltd., Fortron KPS-W312; melt viscosity of 1580 poise at 310 ° C. and shear rate of 1200 / sec) was prepared. Blending 100 parts by weight of PPS powder with 0.3 part by weight of CaCO ₃ (manufactured by Nitto Flour & Chemical Co., Ltd., trade name NITOREX # 30PS) having an average particle size of 0.7 μm and 0.2 parts by weight of calcium stearate, Using a Hensial mixer, mixing was performed for 10 minutes to obtain a mixed powder containing PPS as a main component. This powder was supplied to an extruder and melted at 310 ° C. to obtain resin pellets. This resin pellet was melted at 300 ° C. using an extruder having a diameter of 35 mm, and filtered through a sintered filter having an opening of 40 μm. Subsequently, the film was extruded from a die having a linear lip having a length of 270 mm and a gap of 0.75 mm, and the surface was cast on a metal drum kept at 40 ° C. and cooled to obtain an unstretched film having a thickness of 330 μm. This film was brought into contact with a metal roll whose roll surface temperature was adjusted to about 80 ° C., preheated, and then stretched at a stretching rate of 2500% / min. Stretching was performed.

  Subsequently, the PPS film stretched in the longitudinal direction was introduced into a tenter stretching machine, and stretched 3.6 times in the transverse direction at a stretching rate of 490% / min in an atmosphere adjusted to a temperature of 92 ° C. Immediately after stretching, the transverse relaxation rate was set to 2%, and heat setting was performed at 270 ° C. for 30 seconds. After the heat setting, a slow cooling treatment was performed at the tenter outlet. Thus, a biaxially stretched PPS film having a thickness of about 40 μm was obtained.

  This biaxially stretched PPS film was attached to the delivery part of a roll support type coater, the film was passed through a drying furnace heated to 200 ° C., and the heating process was continuously performed to obtain the heat-treated PPS film of Example 1. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes.

  A 3 cm × 30 cm strip is cut out from the heat-treated PPS film in the vertical and horizontal directions, and the long dimension (dimension on the long side of the strip) is measured, then left in an oven maintained at 160 ° C. for 24 hours, and cooled at room temperature. After that, the dimensions were measured. The ratio of the dimensional change after the heat treatment with respect to the original dimension was determined and used as the dimensional change rate. Negative numbers mean contraction and positive values mean expansion.

(Example 2)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 220 ° C. to perform the heating step, and the heat-treated PPS film of Example 2 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Example 3)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 235 ° C. to perform the heating step, and the heat-treated PPS film of Example 3 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

Example 4
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 240 ° C. to perform the heating step, and the heat-treated PPS film of Example 4 was obtained. The heating time was 30 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 3 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Example 5)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 260 ° C. to perform the heating step, and the heat-treated PPS film of Example 5 was obtained. The heating time was 30 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 3 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Example 6)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 200 ° C. to perform the heating step, and the heat-treated PPS film of Example 6 was obtained. The heating time was 17 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Example 7)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 200 ° C. to perform the heating step, and the heat-treated PPS film of Example 7 was obtained. The heating time was 33 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 1)
A strip of 3 cm × 30 cm was cut out in the longitudinal direction and the transverse direction from the biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 to obtain a PPS film of Comparative Example 1. The rate of dimensional change after holding this film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 2)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 160 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 2 was obtained. The heating time was 30 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 0.1 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 3)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 290 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 3 was obtained. The heating time was 30 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 3 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 4)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 160 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 4 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 10 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 5)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 200 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 5 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 10 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 6)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 220 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 6 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 10 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

(Comparative Example 7)
The biaxially stretched PPS film before the heating step obtained by the method shown in Example 1 was passed through a drying furnace heated to 235 ° C. to perform the heating step, and a heat-treated PPS film of Comparative Example 7 was obtained. The heating time was 60 seconds. When heating, the tensile stress that the biaxially stretched PPS film receives in the winding direction by winding with a winder was 10 kgf corresponding to a film having a cross-sectional area of 1 m width and 40 μm thickness. Also, heating was performed without applying any force in the lateral direction. The heat-treated PPS film obtained was good with no noticeable color or flatness changes. The rate of dimensional change after holding this heat treated PPS film at 160 ° C. for 24 hours was calculated by the same method as in Example 1.

  The results are summarized in Table 2. The shrinkage stress in Table 2 is a measured value of the shrinkage stress per 1 m width of a 40 μm-thick biaxially stretched PPS film at each temperature.

Claims (4)

A heat setting treatment step of heat setting the biaxially stretched poly-p-phenylene sulfide film at a relaxation rate of 0.1 to 10%;
A method for producing a heat-treated poly-p-phenylene sulfide film, comprising a heating step of heating the poly-p-phenylene sulfide film after the heat setting treatment,
In the heating step, the heating is performed at a heating temperature selected from the range of more than 160 ° C. and less than 290 ° C., and the tensile stress smaller than the shrinkage stress at the heating temperature of the biaxially stretched poly-p-phenylene sulfide film Is added to the biaxially stretched poly-p-phenylene sulfide film in one direction. In the heating step, the winding is continuously performed while winding the biaxially stretched poly-p-phenylene sulfide film,
The manufacturing method according to claim 1, wherein a tensile stress smaller than the shrinkage stress is applied to the biaxially stretched poly-p-phenylene sulfide film in a winding direction.   The manufacturing method according to claim 1, wherein the tensile stress is equivalent to a film having a cross-sectional area of 1 m width and 40 μm thickness and is more than 0 kgf and less than 20 kgf.   A heat-treated poly-p-phenylene sulfide film obtainable by the production method according to claim 1.