JP2015067683A - Plastic film, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic film and a manufacturing method of the film which are sufficiently excellent in thermal dimensional stability in a high-temperature range of 200°C or more.SOLUTION: A biaxially oriented plastic film contains particular polyaryl ether ketone-based resin, such as polyether ketone ketone, in which thermal expansion coefficient when temperature rises from 200°C to 250°C is 50 ppm/°C or less under the condition of tensile load at 2.5 gf/2 mm width and temperature rising speed at 10°C/min., and which is used at the temperature of 200°C or more and 300°C or less. In a manufacturing method of the plastic film, after a precursor film containing particular polyaryl ether ketone-based resin, such as polyether ketone ketone, is manufactured, a simultaneous biaxial stretching process including at least heating treatment is implemented to the precursor film.

Description

  The present invention relates to a plastic film, particularly a heat-resistant plastic film, and a method for producing the same.

  In recent years, in the fields of electronic equipment, semiconductors, solar cells, etc., lamination technology of plastic film and metal foil, deposition technology and sputtering technology on plastic film, lamination technology of plastic film and ceramic, and various resins on plastic film Complex technologies such as coating technology and lamination technology are prosperous and tend to be complicated. The obtained composite such as a laminate may be used as a product as it is, or a product obtained by peeling and removing a plastic film from the composite as a so-called process film (release film). Sometimes used. As described above, the plastic film is used for various purposes.

  At the time of compounding, heat is generally applied to the plastic film in many cases, and the case where a higher temperature is applied is increasing. Furthermore, with the recent demand for higher performance, the heat resistance required for plastic films has become severe. Specifically, when the plastic film undergoes dimensional fluctuations due to heat when the metal foils are laminated, the laminated body is warped as a whole, and thus the plastic film is required to have good thermal dimensional stability.

  On the other hand, for the purpose of improving the stability at the time of melt extrusion molding, a technique for stretching a film containing polyether ether ketone at a specific blending amount has been reported (Patent Document 1). However, sufficient thermal dimensional stability was still not obtained by simply stretching the film.

JP 7-178804 A

  An object of the present invention is to provide a plastic film having a sufficiently high thermal dimensional stability at a high temperature and a method for producing the same.

（式（Ｉ）中、Ａｒ^１およびＡｒ^２はそれぞれ独立して置換基を有しても良いアリーレン基である；ｊは１〜３の整数である；ｋは２〜４の整数である）。 The present invention contains a polyaryl ether ketone resin having a repeating unit represented by the following general formula (I),
The coefficient of thermal expansion when heated from 200 ° C. to 250 ° C. under a tensile load of 2.5 gf / 2 mm width and a temperature increase rate of 10 ° C./min is 50 ppm / ° C. or less,
A biaxially oriented plastic film characterized by being used at a temperature of 200 ° C. or higher and 300 ° C. or lower:

(In formula (I), Ar ¹ and Ar ² are each independently an arylene group which may have a substituent; j is an integer of 1 to 3; k is an integer of 2 to 4) .

  The present invention also relates to a method for producing a plastic film, in which a precursor film containing the polyaryletherketone resin is produced, and then a simultaneous biaxial stretching process including at least a heat treatment process is performed on the precursor film.

  The plastic film of the present invention is sufficiently excellent in thermal dimensional stability.

  The plastic film according to the present invention is a biaxially oriented film containing a polyaryletherketone resin. Biaxial orientation means that the polymer molecules constituting the film are oriented mainly in two directions different from each other in the in-plane direction of the film, preferably in two directions substantially perpendicular to each other. For example, it can be achieved by simultaneous biaxial stretching described later. In the present invention, a film containing a polyaryletherketone-based resin is converted into a biaxially oriented film by simultaneous biaxial stretching, thereby comparing with a film that is not biaxially oriented and a biaxially oriented film by sequential biaxial stretching. A sufficiently excellent thermal dimensional stability is exhibited.

  In the present specification, the thermal dimensional stability means a film characteristic in which expansion and contraction of the film, particularly expansion, is sufficiently prevented even when the film is heated.

で表される繰り返し単位（以下、単に「繰り返し単位Ｉ」ということがある）を有する熱可塑性ポリマーである。すなわちポリアリールエーテルケトン系樹脂は、１以上のアリールエーテル単位と２以上のアリールケトン単位とからなる繰り返し単位Ｉからなる熱可塑性ポリマーである。繰り返し単位Ｉの代わりに、アリールケトン単位を１つしか有さない繰り返し単位を有するポリマー、例えば、いわゆるポリエーテルエーテルケトン、を使用すると、本発明ほど十分な熱寸法安定性は得られない。 <Polyaryl ether ketone-based resin>
The polyaryletherketone resin contained in the plastic film of the present invention has the formula (I);

Is a thermoplastic polymer having a repeating unit represented by the following (hereinafter sometimes simply referred to as “repeating unit I”). That is, the polyaryletherketone resin is a thermoplastic polymer composed of repeating units I composed of one or more arylether units and two or more arylketone units. If a polymer having a repeating unit having only one aryl ketone unit, for example, a so-called polyether ether ketone, is used in place of the repeating unit I, sufficient thermal dimensional stability as in the present invention cannot be obtained.

In formula (I), Ar ¹ is an arylene group which may have a substituent. Examples of the arylene group for Ar ¹ include a 1,4-phenylene group, a 1,3-phenylene group, and a 2,6-naphthylene group. Examples of the substituent for Ar ¹ include an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Preferred Ar ¹ is a 1,4-phenylene group.
j is the number of aryl ether units, preferably an integer of 1 to 3, more preferably an integer of 1 to 2.

Ar ² is an arylene group which may have a substituent. Examples of the arylene group for Ar ² include the same arylene groups as the arylene group for Ar ¹ . Examples of the substituent for Ar ² include the same substituents as the substituent for Ar ¹ . Preferred Ar ² is a 1,4-phenylene group.
k is the number of aryl ketone units, preferably an integer of 2 to 4, more preferably an integer of 2 to 3.

  The total number of the number j of aryl ether units and the number k of aryl ketone units is usually 3-6, preferably 3-5.

When the repeating unit I has two or more aryl ether units, the two or more aryl ether units may be the same, or the arylene group, the substituent, or the number thereof may be different.
In the repeating unit I, two or more aryl ketone units may be the same, or an arylene group, a substituent, or the number thereof may be different.

In the repeating unit I, the direction of the aryl ether unit and the aryl ketone unit may be any direction in which groups such as an ether bond group and a ketone group and an arylene group are alternately arranged.
In the repeating unit I, the arrangement order of the aryl ether unit and the aryl ketone unit may be arbitrary, but preferred repeating unit I is a repeating unit having an aryl ether unit at one end and an aryl ketone unit at the other end.

  Specific examples of preferable repeating unit I constituting the polyaryl ether ketone-based resin include repeating units represented by structural formulas (a1) to (a3) shown below.

In formula (a1), three n are each independently an integer of 0 to 4, and preferably all n are 0. Three Rs are each independently selected from the same groups as the substituents of Ar ¹ described in the above formula (I).
In formula (a2), four n are each independently an integer of 0 to 4, and preferably all n are 0. The four R's are each independently selected from the same groups as the substituents for Ar ¹ described in the above formula (I).
In formula (a3), five n are each independently an integer of 0 to 4, preferably all n are 0. The five R's are each independently selected from the same groups as the substituents for Ar ¹ described in the above formula (I).

  The polyaryl ether ketone-based resin may be a polymer composed of a single repeating unit I, or may be a polymer composed of two or more kinds of repeating units I, and preferably has the structural formulas (a1) to ( It is a polymer comprising one or more types of repeating units selected from the repeating units of a3), more preferably a polymer comprising one type of repeating units selected from the repeating units of structural formulas (a1) to (a3). .

  The present invention does not prevent the polyaryl ether ketone-based resin from containing other repeating units other than the repeating unit I, but from the viewpoint of further improving the thermal dimensional stability, the polyaryl ether ketone-based resin should not contain the other repeating units. Is preferred.

The polyaryl ether ketone-based resin preferably has a glass transition temperature of 80 to 230 ° C, particularly 100 to 200 ° C.
The glass transition temperature can be measured based on JIS K7121.

The polyaryl ether ketone resin preferably has a melting point of 250 to 420 ° C, particularly 280 to 400 ° C.
The melting point can be measured based on JIS K7121.

  The polyaryl ether ketone resin composed only of the repeating unit of the structural formula (a1) is so-called polyether ketone ketone (PEKK).

  The polyaryl ether ketone resin consisting only of the repeating unit of the structural formula (a2) is so-called polyether ether ketone ketone (PEEKK).

  The polyaryl ether ketone resin composed only of the repeating unit of the structural formula (a3) is so-called polyether ketone ether ketone ketone (PEKEKK).

  The polyaryl ether ketone resin may be produced by any method. For example, JP-A-50-27897, JP-A-51-119797, JP-A-52-28000. , Japanese Patent Publication No. 54-90296, Japanese Patent Publication No. 55-23574, Japanese Patent Publication No. 56-2091, and the like. An example of a preferable production method is a method in which a benzene ring having a ketone group in which chlorine is bonded to both ends as an electrophile is bonded to benzophenone by a Friedel-Crafts reaction using aluminum chloride or the like as a catalyst. It is not limited.

  In the plastic film, the polyaryletherketone resin may contain two or more polyaryletherketone resins having different compositions, glass transition temperatures and / or melting points within the above-mentioned range.

  The plastic film of the present invention may contain other polymers in addition to the polyaryletherketone resin as long as it does not adversely affect the thermal dimensional stability and film forming property.

  As the other polymer, a polymer having a glass transition temperature of 230 ° C. or lower, particularly 50 to 200 ° C. is used, and from the viewpoint of film forming property, the glass transition temperature is preferably a polyaryletherketone resin contained in a plastic film Use lower polymer. Specific examples of other polymers include, for example, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate; polyphenylene sulfite; polyarylate; Hong; polyphenylene ether; polyether ketone (PEK); polyether ether ketone (PEEK) and the like.

  The content ratio of the polyaryletherketone resin to the polymer component in the plastic film is preferably 60% by weight or more, more preferably 80% by weight or more, and most preferably 90% from the viewpoint of further improving the thermal dimensional stability. % By weight or more. When two or more kinds of polyaryletherketone resins are contained, the total ratio thereof may be within the above range. The polymer component is a mixture of a polyaryletherketone resin and the other polymer contained as required.

<Additives>
In addition to the polymers described above, the plastic film may contain additives such as a colorant, an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, a crystal nucleating agent, and a flame retardant.

  As the colorant, any pigments and dyes used in the field of plastic films can be used. The content ratio of the colorant is not particularly limited as long as the object of the present invention is achieved. For example, 1 to 30% by weight is preferable with respect to the polymer component.

<Plastic film manufacturing method>
The plastic film of the present invention can be produced by the following method.
For example, the polyaryletherketone resin and other polymers and additives that are optionally contained are mixed in a predetermined ratio, melted and kneaded to produce a precursor film, and then the obtained precursor film Then, a biaxial stretching process including at least a heat treatment process is performed.

  A well-known method can be employ | adopted for the manufacturing method of a precursor film. For example, a mixture composed of desired components may be melted and kneaded with an extruder, the kneaded material is extruded from a T die, and then cooled.

  The thickness of the precursor film is not particularly limited, and is, for example, 20 to 2000 μm, and preferably 30 to 1000 μm.

  The biaxial stretching step is a step of performing heat treatment after performing biaxial stretching. By such a biaxial stretching process, the glass transition temperature of the film can be increased, the thermal expansion coefficient can be decreased, or the absolute value of the thermal shrinkage ratio can be decreased.

  Biaxial stretching is performed for MD and TD. The stretching method includes a sequential biaxial stretching method and a simultaneous biaxial stretching method, and a simultaneous biaxial stretching method is preferred. Instead of simultaneous biaxial stretching, after performing stretching in one direction of MD or TD and then performing sequential biaxial stretching in which stretching is performed in the other direction, the coefficient of thermal expansion in the direction in which stretching was performed first The reduction width is reduced and the thermal dimensional stability is reduced. If uniaxial stretching is performed instead of biaxial stretching, the coefficient of thermal expansion in the non-stretched direction does not decrease, and the thermal dimensional stability decreases. In the present specification, MD means a so-called flow direction, and means a direction (longitudinal direction) in which the precursor film is taken from the extruder. TD is a so-called width direction and means a direction orthogonal to the MD.

  When biaxial stretching is performed, the stretching ratio, stretching temperature, and stretching speed are not particularly limited as long as the object of the present invention is achieved. This is because the thermal dimensional stability is further improved.

The stretching ratio is within a range in which breakage of 2.0 times or more does not occur in both MD and TD, and is particularly preferably 2.0 to 5.0, and more preferably 2.2 to 3.5 times. It is preferable that the draw ratios of MD and TD are approximate. Specifically, when the MD draw ratio is P _MD and the TD draw ratio is P _TD , “P _TD −P _MD ” is preferably −0.6 to +0.6, more preferably −0.3. ~ + 0.3. The MD draw ratio is a ratio based on the MD length immediately before the drawing. The stretching ratio of TD is a ratio based on the TD length immediately before stretching.

  By adjusting the draw ratio within the above range, the reduction width of the thermal expansion coefficient can be controlled. For example, when the draw ratio in a predetermined direction is increased, the range of decrease in the coefficient of thermal expansion in that direction is increased.

The stretching temperature is Tg _P or more and Tg _P + 30 ° C. or less when the glass transition temperature of the polymer component constituting the film is Tg _P (° C.), and preferably Tg from the viewpoint of further improving the thermal dimensional stability. _{It is P} ° C. or more and Tg _P + 25 ° C. or less. The stretching temperature is the atmospheric temperature at which stretching is performed. When the polymer component is composed of two or more kinds of polymers, the Tg _P of the polymer component is the sum of values obtained by multiplying the glass transition temperature of each polymer by the content ratio of the polymer.

  By adjusting the stretching temperature within the above range, it is possible to control the reduction range of the thermal expansion coefficient. For example, when the stretching temperature is lowered, the range of decrease in the thermal expansion coefficient is increased.

The stretching speed is 50 to 10,000% / min in both the MD direction and the TD direction, preferably 100 to 5000% / min, more preferably 100 to 3000% / min.
The stretching speed is a value calculated by {(dimension after stretching / dimension before stretching) -1} × 100 (%) / stretching time.

  By adjusting the stretching speed within the above range, the range of decrease in the coefficient of thermal expansion can be controlled. For example, when the stretching speed is increased, the reduction width of the thermal expansion coefficient is increased.

The heat treatment is a process for fixing the orientation of the polymer molecules by holding the stretched film at a temperature equal to or higher than the stretching temperature. The heat treatment temperature is Tg _P + 40 ° C. or higher and Mp _P or lower when the glass transition temperature of the polymer component constituting the film is Tg _P (° C.) and the melting point is Mp _P (° C.). From the viewpoint of further improvement, it is preferably Tg _P + 50 ° C. or higher and Mp _P −20 ° C. or lower. The heat treatment temperature is an ambient temperature for holding the film. When the polymer component is composed of two or more types of polymers, the Mp _P of the polymer component is the sum of values obtained by multiplying the melting point of each polymer by the content ratio of the polymer.

  The heat shrinkage absolute value can be controlled by adjusting the heat treatment temperature within the above range. For example, when the heat treatment temperature is increased, the absolute value of the heat shrinkage rate is decreased.

  The heat treatment may be a tension-type heat treatment in which the heat treatment is performed while maintaining the tension during the biaxial stretching treatment, or a relaxation-type heat treatment in which the tension is relaxed simultaneously with the start of the heat treatment. Alternatively, after performing the heat treatment (first heat treatment) while maintaining the tension, a combined heat treatment may be performed in which the tension is relaxed and the heat treatment (second heat treatment) is performed. Preferably, relaxation heat treatment is performed. When the heat treatment is performed by any of the above methods, the heat treatment temperature is set within the above range.

When the heat treatment is performed in the above-described relaxation type or composite type, the relaxation factor is 0.8 to 1 for both MD and TD from the viewpoint of reducing the absolute value of the heat shrinkage rate, further improving the thermal dimensional stability, and flatness of the film. It is preferably 0.000 times, more preferably 0.85 to 1.00 times, and most preferably 0.85 to 0.98 times. It is preferable that the relaxation ratios of MD and TD are approximate. Specifically, when the MD relaxation rate is Q _MD and the TD relaxation rate is Q _TD , “Q _TD -Q _MD ” is preferably −0.1 to +0.1, more preferably −0.05. ~ + 0.05, most preferably -0.02 to +0.02. The MD relaxation ratio is a magnification based on the MD length immediately after stretching. The relaxation factor of TD is a magnification based on the TD length immediately after stretching.

  By adjusting the relaxation magnification within the above range, the absolute value of the heat shrinkage rate can be controlled. For example, if the relaxation magnification in a predetermined direction is reduced, the amount of decrease in the absolute value of the heat shrinkage rate in that direction increases.

<Plastic film>
The thickness in particular of the plastic film of this invention is not restrict | limited, For example, it is 10-150 micrometers, Preferably it is 12-125 micrometers, More preferably, it is 15-50 micrometers.

  The plastic film of the present invention exhibits extremely excellent thermal dimensional stability. As a result, even when the plastic film of the present invention is used as a heat-resistant film and laminated on the film under high temperature conditions, for example, warping can be sufficiently prevented.

  For details on the thermal dimensional stability, the plastic film of the present invention has, for example, a thermal expansion coefficient within a specific range, and preferably a thermal expansion coefficient and a thermal contraction coefficient within a specific range, respectively.

  Specifically, the coefficient of thermal expansion when the temperature is increased from 200 ° C. to 250 ° C. under a tensile load of 2.5 gf / 2 mm width and a temperature increase rate of 10 ° C./min is 50 ppm / ° C. or less, preferably 40 ppm. / ° C. or less, more preferably 30 ppm / ° C. or less. The coefficient of thermal expansion is within the above range for both the MD and TD directions. If the thermal expansion coefficient is too large, the thermal dimensional stability is lowered and warping cannot be prevented sufficiently. The thermal expansion coefficient of the plastic film of the present invention is usually 1 to 50 ppm / ° C., preferably 3 to 40 ppm / ° C., more preferably 5 to 30 ppm / ° C.

  Regarding the thermal expansion coefficient, from the viewpoint of more sufficiently preventing warpage, the absolute value of the difference between the thermal expansion coefficient MD and TD is preferably 30 ppm / ° C. or less, more preferably 20 ppm / ° C. or less, and still more preferably. 10 ppm / ° C. or less.

  In the present specification, the coefficient of thermal expansion is defined by hanging a test piece (2 mm × 25 mm) so that the longitudinal direction is in the vertical direction, and applying a tensile load of 2.5 gf / 2 mm width to the lower end of the test piece. It is a coefficient of thermal expansion when the ambient temperature is raised from 200 ° C. to 250 ° C. at a rate of temperature increase of 10 ° C./min. The coefficient of thermal expansion is measured when the tensile direction is MD and when it is TD, and is specifically measured by the method described later. As for the value of the coefficient of thermal expansion, a positive value means expansion, and a negative value means contraction.

  The absolute value of the heat shrinkage at 200 ° C. is 2.5% or less, preferably 2.0% or less, more preferably 1.5% or less. The absolute value of the heat shrinkage rate is within the above range in both the MD and TD directions. If the absolute value of the heat shrinkage rate is too large, the thermal dimensional stability is lowered and warping cannot be sufficiently prevented.

  With respect to the heat shrinkage rate, the absolute value of the difference between the MD and TD of the heat shrinkage rate is preferably 2.0% or less, more preferably 1.5% or less, more preferably from the viewpoint of more sufficiently preventing warpage. Preferably it is 1.0% or less, Most preferably, it is 0.5% or less.

  In the present specification, the heat shrinkage rate is the heat shrinkage rate in each direction of MD and TD when a test piece (15 mm × 120 mm) is left for 30 minutes at an atmospheric temperature of 200 ° C., and specifically by the method described later. Measured. As for the value of the heat shrinkage rate, a positive value means shrinkage, and a negative value means expansion.

  The plastic film of the present invention is useful as a heat-resistant film. For example, it is useful as a film used in a high temperature environment of 200 ° C. or more and 300 ° C. or less, preferably more than 200 ° C. and 300 ° C. or less.

  In the present invention, the heat resistant film is a film that requires heat resistance such as thermal dimensional stability even in the high temperature environment because it is used in the high temperature environment. Examples of the heat-resistant film include a heat-resistant film for lamination, a heat-resistant film for release, a heat-resistant film for sticking, and the like.

The heat-resistant film for lamination is a film used for laminating other layers on its own surface, and is a film that requires heat resistance because it is exposed to the high temperature environment at the time of lamination. Examples of other layers include a metal layer, a ceramic layer, and a resin layer.
The heat-resistant film for lamination produces, for example, a base film used when manufacturing a flexible printed circuit board such as an electronic device, a base film used when manufacturing a flexible solar cell, and a back sheet for solar cell. It is useful as a base film used at the time.

  Specifically, for example, when the plastic film of the present invention is used as a substrate film for a printed circuit board, on the film, for example, for wiring in the above high temperature environment by a dry laminating method, a vapor deposition method or a sputtering method. A metal layer is formed. Even in such applications, the plastic film of the present invention is sufficiently prevented from dimensional variation and deformation, so that the laminate can be sufficiently prevented from warping and the film can be sufficiently prevented from peeling off from the metal layer. When a plastic film having a thermal expansion coefficient larger than the range specified in the present invention when heated from 200 ° C. to 250 ° C. is used as a substrate film for a printed circuit board in a high temperature environment exceeding 200 ° C., the substrate followability It is conceivable to cause problems such as warpage and significant deformation.

  The heat-release film for mold release is a so-called process film. The heat-release film for release is a film that is used as a support layer or protective layer for the other layer by forming another layer on the film, but is finally peeled and removed. is there. The heat release film for mold release is subjected to heat in another layer forming step and subsequent steps, and is exposed to the high temperature environment. Therefore, heat resistance is required to prevent dimensional variation. The heat release film for release is useful as, for example, a process film for forming a resin film, a process film for forming a ceramic thin film, a process film for forming a metal thin film, and the like.

  Specifically, when the plastic film of the present invention is used as a heat-resistant film for release, the metal layer is formed on the film, for example, in the above high temperature environment, as in the case of using it as a base film for a printed circuit board. Is formed. Even in such applications, the plastic film of the present invention is sufficiently prevented from dimensional variation and deformation, and can sufficiently prevent warping of the laminate, so that a metal layer having a sufficiently uniform thickness can be formed at the time of forming the metal layer. Can be formed. When a plastic film having a coefficient of thermal expansion larger than the range specified in the present invention when heated from 200 ° C. to 250 ° C. is used as a heat-resistant film for release in a high temperature environment exceeding 200 ° C., it follows the substrate. Due to its low nature, warping occurs.

The heat-resistant film for sticking is useful, for example, as a base film of an adhesive tape used in the above high temperature environment.
Specifically, for example, when the plastic film of the present invention is used as a base film of a heat-resistant adhesive tape, the plastic film of the present invention is sufficiently prevented from dimensional variation, strength reduction and deformation. Warp and peeling of the adhesive tape can be sufficiently prevented. When a plastic film having a thermal expansion coefficient larger than the range specified in the present invention when heated from 200 ° C. to 250 ° C. is used as a base film of a heat-resistant adhesive tape in a high temperature environment exceeding 200 ° C., it is attached. However, it may be peeled off immediately.

Examples 1-2 / Comparative Examples 1-3
First, the components listed in the table were melted and kneaded with an extruder, degassed and filtered to obtain pellets. This is because if the polymer contains a volatile component, gel eyes adhere to the lip portion of the T-die of the extruder and affect the film surface.
Next, the resin was melt extruded from a T die at a resin temperature of 390 ° C. by an extruder, and then cooled to obtain a precursor film. The precursor film was stretched and heat-treated under the conditions described in the table.
The heat treatment was a relaxation heat treatment at a predetermined temperature and a relaxation magnification.
Simultaneous biaxial stretching was performed simultaneously for MD and TD.
In Examples 1 and 2, the PEKK film was stretched and heat-treated.
In Comparative Example 1, neither stretching nor heat treatment was performed on the PEKK film.
In Comparative Example 2, the PEEK film was stretched and heat-treated.
In Comparative Example 3, neither stretching nor heat treatment was performed on the PEEK film.

For PEKK, a polymer (Tg = 166 ° C., Tm = 356 ° C.) consisting of only the repeating unit of the structural formula (a1) (all n is 0) was used.
For PEEK, a polymer (Tg = 143 ° C., melting point 343 ° C.) consisting only of repeating units of the following structural formula (a4) was used.

  The film obtained in each example / comparative example was cut into test piece dimensions in the following evaluation methods, and each item was evaluated.

Thermal expansion coefficient (200 ℃ to 250 ℃)
Using a thermomechanical measuring device (TMA-50, manufactured by Shimadzu Corporation), a test piece (film; 2 mm × 25 mm) is suspended so that the longitudinal direction of the test piece is in the vertical direction, and is attached to the lower end of the test piece. A tensile load of 2.5 gf / 2 mm width was applied. Thereafter, the ambient temperature was raised at a rate of temperature rise of 10 ° C./min, the dimensional change from 200 ° C. to 250 ° C. was converted to the amount of change per 1 ° C., and the thermal expansion coefficient R ₁ was measured. The coefficient of thermal expansion was measured when the tensile direction was MD and TD. For R _1, a positive value means that the inflated.
A: R ₁ ≦ 30 ppm / ° C. (best);
○: 30 ppm / ° C. <R ₁ ≦ 40 ppm / ° C. (good);
Δ: 40 ppm / ° C. <R ₁ ≦ 50 ppm / ° C. (no problem in practical use);
×: 50 ppm / ° C. <R ₁ (practical problem).

Thermal expansion coefficient (other temperature range)
The coefficient of thermal expansion was measured by the same method as the method for measuring the coefficient of thermal expansion, except that the temperature range for measuring the dimensional change was a predetermined range.

Thermal contraction rate A straight line having a length of 100 mm was drawn on a test piece (film; 15 mm × 120 mm) in parallel to the MD direction and the TD direction, respectively. The test piece was left in a standard state (temperature 23 ° C. × humidity 50%) for 2 hours, and then the length of the straight line before the test was measured. Subsequently, the sample was left standing for 30 minutes in a hot air circulation oven set to an atmosphere of 150 ° C., 180 ° C., or 200 ° C. for 30 minutes, and then taken out and cooled to a standard state for 2 hours. Then measuring the length of each direction of the straight line to obtain the amount of change from the length before the test, to determine the heat shrinkage R ₂ as a percentage of variation relative to the length before the test. A positive value for R ₂ means contraction.
A: Absolute value of R ₂ ≦ 1.5% (best);
○: 1.5% <R ₂ absolute value ≦ 2.0% (good);
Δ: 2.0% <absolute value of R ₂ ≦ 2.5% (no problem in practical use);
X: Absolute value of 2.5% <R ₂ (practical problem).

Claims (5)

Containing a polyaryletherketone resin having a repeating unit represented by the following general formula (I),
The coefficient of thermal expansion when heated from 200 ° C. to 250 ° C. under a tensile load of 2.5 gf / 2 mm width and a temperature increase rate of 10 ° C./min is 50 ppm / ° C. or less,
Biaxially oriented plastic film characterized by being used at a temperature of 200 ° C. or higher and 300 ° C. or lower:

(In formula (I), Ar ¹ and Ar ² are each independently an arylene group which may have a substituent; j is an integer of 1 to 3; k is an integer of 2 to 4) .   The plastic film according to claim 1, wherein the absolute value of the heat shrinkage rate at 200 ° C is 2.5% or less.   The plastic film according to claim 1 or 2, wherein the polyaryl ether ketone resin is selected from the group consisting of polyether ketone ketone, polyether ether ketone ketone, and polyether ketone ether ketone ketone.   The plastic film according to any one of claims 1 to 3, wherein the biaxially oriented plastic film is obtained by subjecting a film containing the polyaryletherketone resin to at least simultaneous biaxial stretching. It is a manufacturing method of the plastic film in any one of Claims 1-4,
A method for producing a plastic film, comprising producing a precursor film containing a polyaryletherketone-based resin and then performing a simultaneous biaxial stretching step including at least a heat treatment step on the precursor film.