JP2020075481A - Thermoplastic resin film and manufacturing method therefor - Google Patents

Abstract

To provide a thermoplastic resin film excellent in heat resistance, electric property and processability.SOLUTION: There is provided a thermoplastic resin film consisting of a thermoplastic resin having melting point or softening point of 270°C or higher, having a laminate structure with 2 or more layers, in which at least one layer of the constituted layer is a layer (I) having porosity of 20% or more, and the number of pore with a diameter R of a maximum circumcircle of 2 μm or less in pores contained in 2500 μmof a cross section perpendicular to a surface of the thermoplastic resin film in the layer (I) is 20 or less.SELECTED DRAWING: None

Description

  The present invention relates to a thermoplastic resin film having excellent heat resistance, electrical characteristics, and processability.

Films and non-woven fabrics made of thermoplastic resins such as polyarylene sulfide, polyether imide, polyethylene naphthalate, polyamide, polyether ether ketone, liquid crystal polymer, and fluororesin have heat resistance, electrical characteristics, low hygroscopicity, and high temperature. Since it has excellent dimensional stability and chemical resistance at room temperature, it is preferably used as an insulating material or heat insulating material for electric / electronic parts, battery members, machine parts and automobile parts.
The members to which these thermoplastic resin films are applied have been miniaturized in recent years, and the thermoplastic resin films used in accordance with them are required to retain the same characteristics as the conventional thickness and be thin. There is.
When the thermoplastic resin film is thinned with the same composition, there is a problem that mechanical properties and electrical properties are deteriorated as the thickness is reduced (for example, Patent Documents 1 and 2).
Therefore, a method of making the thermoplastic resin film porous has been proposed in order to maintain both the characteristics of the thermoplastic resin film, particularly the electrical characteristics, and to make the film thinner (for example, Patent Documents 4 and 5). However, since the film to which the above method is applied includes a portion having a low resin density, there is a problem that mechanical properties are significantly reduced and processability is reduced.

JP, 2008-266593, A JP, 2011-127244, A JP, 2013-206818, A JP, 2014-102946, A

  An object of the present invention is to solve the above problems. That is, it is to provide a thermoplastic resin film having excellent heat resistance, electrical characteristics, and processability.

The thermoplastic resin film of the present invention has the following constitution in order to solve the above problems. That is,
A thermoplastic resin film made of a thermoplastic resin having a melting point or a softening point of 270 ° C. or higher, having a laminated structure of two or more layers, and at least one of the constituent layers has a porosity of 20% or more (I). In the layer (I), a heat having 20 or less number of holes having a minimum circumscribed circle diameter R of 2 μm or less among the holes included in a cross section 2500 μm ² perpendicular to the surface of the thermoplastic resin film. Plastic resin film.

INDUSTRIAL APPLICABILITY The thermoplastic resin film of the present invention has excellent heat resistance / electrical properties and processability, and is used for electric / electronic devices, battery members, mechanical parts and automobile parts and insulating materials, printing device members, heat-resistant tapes, circuit boards, mold release. It can be suitably used as a film.

The thermoplastic resin film of the present invention is mainly composed of a thermoplastic resin having a melting point or a softening point of 270 ° C. or higher. Here, the melting point refers to the solid-liquid transition temperature of the resin, and the softening point refers to the temperature at which the thermoplastic resin begins to substantially deform due to heating. In addition, the main component refers to a component that accounts for 60% by mass or more of the resin composition forming the film. By having the above-mentioned thermal characteristics, excellent heat resistance can be exhibited. When the melting point or softening point is lower than 270 ° C., the film tends to deteriorate when used in a high temperature environment of 180 ° C. or higher, and mechanical properties and electrical properties may deteriorate. The higher the melting point or softening point, the higher the heat resistance, but from the viewpoint of productivity, it is preferably 350 ° C or lower. The melting point or softening point of the thermoplastic resin film is more preferably 280 ° C or higher, still more preferably 300 ° C or higher. The melting point of the resin can be evaluated by a differential scanning calorimeter, and the softening point of the resin can be evaluated by a method described later using a thermomechanical analyzer.

  The above-mentioned thermoplastic resin may be either crystalline or amorphous, and examples of the crystalline resin include thermoplastic polyimide resin, polyamide resin, polyether ether ketone, polyarylene sulfide resin (polysulfone, polyether sulfone). , Polyphenylene sulfide, etc.) and the amorphous resin is preferably at least one selected from polyetherimide (PEI), thermoplastic polyamideimide resin, liquid crystal polymer (LCP), and the like. Among them, at least one selected from the group consisting of polyarylene sulfide resin, polyamide resin, thermoplastic polyimide resin, polyetherimide, and polyetheretherketone is preferable from the viewpoint of heat resistance and insulating property, and polyetherimide resin From the viewpoint of processability and productivity, polyarylene sulfide resin and polyether ether ketone are particularly preferable.

  The resin composition constituting the thermoplastic resin film of the present invention can be used by adding an additive within a range that does not impair the effects of the present invention. Specific examples of such additives include organic compounds, thermal decomposition inhibitors, thermal stabilizers, light stabilizers and antioxidants.

  It is also possible to mix and use a resin other than the above-mentioned thermoplastic resins in the resin composition constituting the thermoplastic resin film of the present invention within a range not impairing the effects of the present invention. Specific examples of such resins include polyolefin resins such as polyethylene and polypropylene, polystyrene, polycarbonate, acrylic resins, urethane resins, fluororesins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyketones, and epoxy resins. It is not limited to this.

  The polyarylene sulfide resin preferably used for the thermoplastic resin film of the present invention refers to a copolymer having a repeating unit of-(Ar-S)-. Examples of Ar include units represented by the following formulas (A) to (K).

(R1 and R2 are substituents selected from hydrogen, an alkyl group, an alkoxy group and a halogen group, and R1 and R2 may be the same or different)
The repeating unit is preferably a p-arylene sulfide unit represented by the above formula (1), and typical examples thereof include polyphenylene sulfide, polysulfone, polyether sulfone, polyphenylene sulfide sulfone and polyphenylene sulfide ketone. As a particularly preferable p-arylene sulfide unit, a p-phenylene sulfide unit is preferably exemplified from the viewpoint of film physical properties and economy.

  The polyarylene sulfide resin used in the present invention preferably comprises, as a main constituent unit, a p-phenylene sulfide unit represented by the following structural formula in an amount of 80 mol% or more and 99.9 mol% or less of all repeating units. With the above composition, excellent heat resistance and chemical resistance can be exhibited.

  It is also possible to copolymerize with the copolymerized unit in the range of 0.01 mol% to 20 mol% of the repeating unit.

  Preferred copolymerized units are

(Here, X represents an alkylene, CO or SO ₂ unit.)

(Wherein R represents an alkyl, nitro, phenylene or alkoxy group), and a particularly preferred copolymerized unit is an m-phenylene sulfide unit.

  The copolymerization mode of the main constituent unit with the copolymerization component is not particularly limited, but a random copolymer is preferable.

  In the thermoplastic resin film of the present invention, at least one layer of the layers constituting the film contains inorganic particles and has a porosity of 20% or more (I). By having the above-mentioned composition, the electric characteristic as a thermoplastic resin film can be improved. The porosity is preferably 20 to 70%, more preferably 25 to 70%, further preferably 25 to 60%. Here, the porosity refers to the ratio of the area of the voids included in the image when the cross-sectional area of any size of the layer (I) is 100, and the cross section of any size of the layer (I). When no holes are observed in the image, the porosity is 0%. When the porosity is less than 20%, the number of pores contained in the thermoplastic resin film decreases, and the proportion of air having a low dielectric constant in the film decreases, so that the electrical characteristics may deteriorate. Further, the higher the porosity, the more preferable, but 70% or less is preferable from the viewpoint of maintaining productivity. The porosity can be set within the above range by applying the particle concentration and film forming conditions described later. The porosity can be confirmed by evaluating the cross section of the thermoplastic resin film by the method described below.

  As a method for forming pores in the layer (I) constituting the thermoplastic resin film of the present invention, a dry method (melting the resin and extruding it into a sheet shape is preferable because it is easy to process and excellent in productivity. It is preferable to use a method in which the material is made porous by stretching. Further, among dry methods, in consideration of retention stability and productivity, a method of forming pores around particles by adding inorganic particles to a layer for forming pores and stretching is preferably used. ..

  The preferred concentration of particles contained in the layer (I) constituting the thermoplastic resin film of the present invention is when the raw material composition of the layer comprising the resin constituting the thermoplastic resin film and other additives is 100% by mass. Further, it is preferably 10% by mass or more, more preferably 10 to 60% by mass, and particularly preferably 20 to 40% by mass. Voids can be formed efficiently by setting the particle concentration within the above range. When the particle concentration is less than 10% by mass, pores are less likely to be formed because the particle concentration is low at the time of producing the film described later, and the electrical characteristics are deteriorated when the thermoplastic resin film is used as a constituent member of the thermoplastic resin film. There are cases. On the other hand, if the particle concentration exceeds 60% by mass, it may be difficult to stretch during production of the thermoplastic resin film, and productivity may decrease.

Regarding the layer (I) that constitutes the thermoplastic resin film of the present invention, of the pores included in about 2500 μm ^{2 in the} cross section perpendicular to the surface of the thermoplastic resin film, the diameter R of the smallest circumscribed circle is 2 μm or less. The number is 20 or less. By having the above-mentioned characteristics, it is possible to improve the average value of the end tear resistance of the thermoplastic resin film in an arbitrary direction and a direction orthogonal thereto. A thermoplastic resin film having a porous structure like the thermoplastic resin film of the present invention tends to have lower mechanical properties than a thermoplastic resin film having no pores of the same thickness. It is considered that one of the causes of this decrease is that the amount of resin per thickness is reduced by having a porous structure. However, since the formation of pores is indispensable for improving the electrical characteristics, as a result of diligent studies on compatibility of the electrical characteristics and the end-cleave resistance, the pore diameter of the layer having a porous structure is controlled within the above range, It has been found that the edge tear resistance can be improved by reducing the minute pores of 2 μm or less, which are the starting points of film breakage. If the number of holes having a minimum circumscribed circle diameter R of 2 μm or less exceeds 20, the number of minute holes that are the starting points of film breakage increases, and the edge tear resistance may decrease. The upper limit of the number of holes having a diameter R of the minimum circumscribed circle of 2 μm or less is more preferably 15 or less, and further preferably 10 or less. The lower the lower limit of the number of holes, the better. The above characteristics can be achieved by controlling the particle size contained in the layer (I) within the range described below. The diameter and number of pores can be evaluated by the method described later.

  As the particles preferably used in the layer (I) and the layer (II) described below that form the thermoplastic resin film of the present invention, alumina, silica, titania, zirconia, magnesia, ceria, yttria, zinc oxide, iron oxide, etc. Ceramics and nitride ceramics such as silicon nitride, titanium nitride, and boron nitride, silicon carbide, calcium carbonate, aluminum sulfate, barium sulfate, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite , Ceramics such as sericite, mica, amesite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth and silica sand, and inorganic compounds such as glass fiber. The particles to be used may be one kind or a mixture of plural kinds. Among the above, calcium carbonate, barium sulfate, zinc oxide and silica are preferable from the viewpoint of dispersibility, and calcium carbonate and silica are particularly preferable from the viewpoint of low cost.

  The particles preferably used in the layer (I) constituting the thermoplastic resin film of the present invention can be surface-treated within a range that does not impair the physical properties of the thermoplastic resin film.

  The particles preferably used in the layer (I) constituting the thermoplastic resin film of the present invention are a laser diffraction method (a method of obtaining the particle size by analyzing the intensity distribution of the diffracted light obtained by irradiating the particles with a laser beam. The particle diameter of 50% numerical value (D50: median diameter) corresponding to the median value of the particle size distribution (cumulative distribution) obtained by 1) is preferably 1 to 10 μm, more preferably 1 to 8 μm, and 1 to More preferably, it is 3 μm. By using the above D50 particles, the aggregation of the particles, which tends to occur when the particles are blended at a high concentration, is suppressed, and the stress concentrates around the particles when stretched, so that in the layer (I) It is possible to efficiently form pores. When the D50 of the particles is less than 1 μm, the surface area of the particles increases, aggregation easily occurs, and the productivity decreases, or voids are less likely to be formed during stretching, and the porosity may decrease. Further, when D50 is larger than 10 μm, film breakage easily occurs during stretching due to particle penetration, and the productivity of the thermoplastic resin film may decrease.

The particles used in the layer (I) constituting the thermoplastic resin film of the present invention preferably have a particle diameter (D5) of 5% of the cumulative distribution obtained by particle size distribution measurement of 0.5 μm or more, It is more preferably 8 μm or more. By setting D5 in the above range, the number of holes having a minimum circumscribing circle diameter R of 2 μm or less among the holes included in a cross section 2500 μm ² can be set in the range described below, and the end tear resistance can be reduced. Can be improved. When D5 is 0.5 μm or less, the fine particles contained in the layer (I) increase, and the increase in the fine particles serves as a starting point of the destruction when the film is physically subjected to a force. There is a case where easy-to-use minute voids increase and mechanical properties, particularly edge crack resistance, decrease. The upper limit of D5 is preferably as close to D50 as possible from the viewpoint of making the particle diameter uniform.

  The particles used for the layer (I) constituting the thermoplastic resin film of the present invention have a particle size (D90) of 90% of the cumulative distribution obtained by particle size distribution measurement, which is preferably 20 μm or less, and 16 μm or less. Is more preferable. When D90 satisfies the above range, the width of the particle size distribution can be narrowed and the stress distribution during stretching can be made uniform, so that the generation of minute pores can be suppressed. When D90 is larger than 20 μm, the content ratio of large-diameter particles in which stress is likely to be concentrated at the time of stretching increases, so that non-uniform stretching occurs, and minute pores are formed in the vicinity of small-diameter particles in which stretching stress is difficult to be transmitted. May increase and mechanical properties may deteriorate. The lower limit of D90 is preferably as close as possible to D50 from the viewpoint of making the particle diameter uniform.

  The particles used in the layer (I) constituting the thermoplastic resin film of the present invention preferably have a ratio of D90 and D50 (D90 / D50) obtained by particle size distribution measurement of 3.0 or less, and D2.0. The following is more preferable. By setting D90 / D50 within the above range, the width of the particle size distribution can be narrowed and the stress distribution during stretching can be made uniform, so that the generation of minute voids can be suppressed. When D90 / D50 is larger than 3.0, stress at the time of stretching is concentrated around the contained particles of D90 or more, and it becomes difficult to uniformly propagate the stress to the particles on the smaller diameter side than D50, resulting in minute pores. May increase. The lower limit of D90 / D50 is preferably as close to 1 as possible from the viewpoint of making the particle diameter uniform. The particle size distribution of the particles contained in the thermoplastic resin film can be confirmed by the method described later.

  The particle diameter and particle concentration of 5, 50 and 90% of the cumulative distribution obtained by the particle size distribution measurement of the particles preferably used in the layer (I) constituting the thermoplastic resin film of the present invention are determined by the method described below. You can check.

When the layer (II) is a layer other than the layer (I) constituting the thermoplastic resin film of the present invention, this layer may or may not contain inorganic particles.
When the layer (II) constituting the thermoplastic resin film of the present invention contains particles, the concentration of the particles is preferably 0.01 to 10 mass% with respect to the layer (II), and 0.01 to 5 mass% is more preferable. With the above concentration, the function of the layer (II) as a support can be exhibited when the film is stretched. When the concentration of the particles contained in the layer (II) exceeds 10% by mass, the film cannot withstand the stress applied to the film during stretching and is easily broken, which may impair the film-forming stability.

  When particles are contained in the layer (II) constituting the thermoplastic resin film of the present invention, the volume average particle diameter of the particles is preferably 0.5 to 20 μm, and preferably 0.5 to 18 μm. It is more preferable from the viewpoint of membrane stability.

  The thermoplastic resin film of the present invention is either an unstretched film, a uniaxially stretched film (fill stretched in any unidirectional direction), or a biaxially stretched film (film stretched biaxially in any direction and its orthogonal direction). However, a biaxially stretched film is preferable from the viewpoint of characteristics and productivity. As a method for obtaining a biaxially stretched film, a sequential biaxial stretching method (a stretching method in which stretching is performed in each direction such as a method of stretching in the longitudinal direction and then in the width direction) is combined, and a simultaneous biaxial stretching method (longitudinal stretching) Direction) and a width direction), or a combination thereof. Among them, the sequential biaxial stretching method is particularly preferable from the viewpoint of productivity. The presence or absence of stretching and the axial direction can be confirmed by measuring the shrinkage rate of the film at 250 ° C. by the method described below.

  The thermoplastic resin film of the present invention has a laminated structure of two or more layers. By having a layer structure of two or more layers, the stretchability of the thermoplastic resin film itself is improved, breakage is suppressed, and productivity can be improved. The laminated structure includes two layers of (I) / (II) composed of layer (I) and layer (II), (I) / (II) / (I), (II) / (I) / ( II), (II) / (I) / (II) / (I), (II) / (I) / (II) / (I) / (II) and the like, but are not limited thereto. Not done. It is also possible to have a layer structure in which a layer having a composition different from (I) to (II) is further added.

  From the viewpoint of productivity, the thickness of the thermoplastic resin film of the present invention is preferably 10 to 350 μm, more preferably 25 to 300 μm. The film thickness and layer thickness can be controlled by adjusting the supply amount of the raw material when obtaining the unstretched sheet. The film thickness and layer thickness can be evaluated by the method described below.

In the thermoplastic resin film of the present invention, it is preferable that the average value of the end tear resistance in terms of 200 μm in an arbitrary direction of the thermoplastic resin film and a direction orthogonal thereto is 100 N / 20 mm or more. By having the above-mentioned characteristics, when the thermoplastic resin film is put into practical use, it is possible to exhibit durability against the stress applied in the thickness direction of the thermoplastic resin film. If the edge tear resistance is less than 100 N / 20 mm, it may easily break when stress is applied in the thickness direction, and it may not be practical. The higher the upper limit of the edge tear resistance, the more preferable. However, the feasible range is 1500 N / 20 mm or less. The average value of edge crack resistance in terms of 200 μm in an arbitrary direction and a direction orthogonal thereto is more preferably 100 N / 20 mm or more, further preferably 180 N / 20 mm or more. The edge tear resistance can be set within the above range by setting the diameter of the pores contained in a cross section of 2500 μm ² perpendicular to the film surface of the layer (I) within the above range. The edge tear resistance can be evaluated by the method described below.

  The thermoplastic resin film of the present invention preferably has an average elongation retention rate of 50 to 100% after treatment at 200 ° C./1000 hours in an arbitrary direction and a direction orthogonal thereto, and is 80 to 100%. More preferably. By setting the elongation retention rate within the above range, it is possible to maintain the mechanical properties and electrical properties of the thermoplastic resin film when used at high temperature for a long time. If the elongation retention rate is less than 50%, long-term heat resistance is poor, and cracks may occur due to deterioration when used at high temperatures for a long time, or electrical characteristics may deteriorate. It is possible to achieve the elongation retention within the above range by using the above-mentioned thermoplastic resin film. The elongation retention rate can be evaluated by the method described below.

The thermoplastic resin film of the present invention preferably has a dielectric constant of 2.8 or less at a frequency of 10 GHz under a temperature of 23 ° C. and 65% RH, and more preferably 2.5 or less. By having the above characteristics, when used as a circuit board material in a high frequency region, it is possible to reduce the odd capacity of the insulating material, so that transmission loss can be effectively suppressed. When the dielectric constant is larger than 2.8, the transmission loss may increase when used as a substrate material. The lower the dielectric constant, the more preferable, but the feasible range is 1.8 or more. The dielectric constant within the above range can be achieved by setting the composition and characteristics of the laminated film to the above-mentioned constitution. The dielectric constant can be evaluated by the method described below.
The absolute value of the transmission loss of the laminated film of the present invention at 23 ° C. and 65% RH at 10 to 40 GHz is preferably less than 25 dB / 100 mm, more preferably less than 15 dB / 100 mm. The transmission loss represents the degree of deterioration of the signal flowing on the communication line. If the transmission loss is larger than 25 dB / 100 mm, the input signal on the circuit line is greatly deteriorated, and it becomes difficult to apply it as a component of equipment during large capacity communication. The lower the absolute value of the transmission loss, the more preferable. The transmission loss within the above range can be achieved by making the laminated film have the above-mentioned dielectric constant. The transmission loss can be evaluated by the method described below.

  The method for producing the thermoplastic resin film of the present invention will be described by taking the case of using a polyarylene sulfide resin as an example.

  The method for producing the polyarylene sulfide resin preferably used for the thermoplastic resin film of the present invention will be described. Sodium sulfide and p-dichlorobenzene are mixed and reacted in an amide polar solvent such as N-methyl-2-pyrrolidone (NMP) at high temperature and high pressure. If necessary, a copolymerization component such as m-dichlorobenzene or trihalobenzene can be included. A caustic potash, an alkali metal salt of a carboxylic acid, or the like is added as a polymerization degree adjusting agent, and a polymerization reaction is performed at 230 to 290 ° C. After the polymerization, the polymer is cooled, and the polymer is made into a water slurry and filtered with a filter to obtain a wet granular polymer. An amide-based polar solvent is added to this granular polymer, and the mixture is washed by stirring at a temperature of 30 to 100 ° C, washed several times with ion-exchanged water at 30 to 80 ° C, and washed several times with an aqueous metal salt solution such as calcium acetate. After washing, it is dried to obtain a granular polymer of polyarylene sulfide resin. The granular polymer and the inorganic particles are mixed at an arbitrary ratio, charged into an extruder with a vent set to 300 to 350 ° C., melt-extruded in a strand shape, cooled with water at a temperature of 25 ° C., and then cut to produce a chip. And used as a raw material for the layer (I). At this time, the addition concentration of the inorganic particles is preferably 1 to 65 parts by mass, and more preferably 5 to 65 parts by mass with respect to 100 parts by mass of the granular polymer.

  In addition, the above-mentioned granular polymer alone, or the granular polymer and inorganic particles and additives are mixed at an arbitrary ratio and charged into an extruder with a vent set to 300 to 350 ° C. to melt-extrude in a strand shape at a temperature of 25 ° C. After cooling with water, a chip is produced by cutting and used as a raw material for another layer (II) having a composition different from that of the layer (I). These two types of chips were separately dried under reduced pressure at 180 ° C. for 3 hours, then supplied to two full flight single-screw extruders each having a melting part set to 300 to 350 ° C., and passed through a filter. Then, in a molten state, three layers were formed in the laminating device on the upper part of the die (the laminating constitution was (I) / (II) / (I), and the laminating ratio was (I) :( II) :( I) = 1: 1: 1). 1 to 1: 10: 1), and then ejected from the T-die type die, and adhered to the cooling drum having a surface temperature of 20 to 70 ° C. while applying an electrostatic charge to rapidly cool and solidify. A non-oriented film in a non-oriented state is obtained.

  Then, in the case of biaxial stretching, the unstretched film obtained above is successively biaxially stretched or simultaneously with the glass transition point (Tg) or higher of the polyarylene sulfide resin in the range of cold crystallization temperature (Tcc) or lower. After being biaxially stretched by a biaxial stretching machine, a single-stage or multi-stage heat treatment is performed at a temperature in the range of 150 to 280 ° C. to obtain a biaxially oriented film. As a stretching method, a sequential biaxial stretching method (a stretching method in which stretching is performed in each direction such as a method of stretching in the longitudinal direction and then in the width direction) is combined, and a simultaneous biaxial stretching method (the longitudinal direction and the width direction are A method of simultaneously stretching) or a method of combining them can be used. Here, a sequential biaxial stretching method in which stretching is first performed in the longitudinal direction and then in the width direction is illustrated.

  The unstretched film is heated by a heating roll group and stretched in the longitudinal direction (MD direction) by 2.8 to 4.5 times, more preferably 2.8 to 4.0 times in a single stage or in multiple stages of two or more stages. (MD stretching). The stretching temperature is in the range of Tg to Tcc, preferably (Tg + 5) to (Tcc-10) ° C. Then, it cools with a 20-50 degreeC cooling roll group.

  As a stretching method in the width direction (TD direction) following MD stretching, for example, a method using a tenter is generally used. Both ends of this film are gripped by clips, guided to a tenter, and stretched in the width direction (TD stretching). The stretching temperature is preferably Tg to Tcc, more preferably (Tg + 5) to (Tcc-10) ° C. The stretching ratio is preferably 3.0 to 5.0 times, and more preferably 3.0 to 4.5 times from the viewpoint of the flatness of the film.

  At this time, with respect to the stretching ratio of the film, the ratio of the MD ratio to the TD ratio (stretching ratio = MD ratio / TD ratio) is preferably 1.05 or less, more preferably 1.00 or less, and 0.95 or less. More preferable. When the pores contained in the layer (I) are stretched in the MD direction, which is the initial stretching direction, stress concentrates on the interface between the resin and the particles, and peeling occurs. After that, holes that extend in the MD direction starting from this peeling point are formed. At this time, heat is generated due to stress concentration at the particle / resin interface, and when a crystalline thermoplastic resin is used as the resin composition of the film, local crystallization progresses and the plasticity of the resin part due to heating during stretching is increased. It is considered that it interferes with the deformation and forms micropores that form pores, causing embrittlement. Further, it is considered that the amorphous resin causes excessive softening of the resin and causes defective formation of voids. For this reason, if the film is excessively stretched in the MD direction, the crystalline thermoplastic resin is likely to be stretch-ruptured due to the subsequent stretching in the TD direction, or the mechanical strength of the film may be deteriorated. .. Further, the amorphous resin may have a low porosity even though it is biaxially stretched. Therefore, it is preferable that the stretching ratio in the MD direction is as low as possible without impairing the flatness, and the stretching ratio in the TD direction as high as possible in the range not causing film breakage is that the mechanical properties after biaxial stretching, especially edge tear resistance, It is important to maintain the balance of electrical characteristics.

  Next, an operation (heat setting treatment) of heat setting the stretched film under tension is performed. The heat setting temperature is the same throughout the heat treatment zone, either at the same temperature, or in one stage heat setting or in multi-stage heat setting at different temperatures in the first half and the second half of the heat treatment zone. .. The heat setting temperature is preferably 160 ° C. to the melting point (Tm), and is preferably 180 to (Tm-10) ° C. from the viewpoint of suppressing heat shrinkage of the film. After the heat setting treatment, the film is cooled to room temperature and, if necessary, subjected to a relaxation treatment of 1 to 20% in the longitudinal and width directions, the film is cooled and wound to obtain a biaxially stretched thermoplastic resin film.

  Since the thermoplastic resin film of the present invention is excellent in electrical properties and mechanical properties, it is used for various parts of automobiles and electric / electronic materials, particularly insulating papers and heat insulating materials for various motors, circuit board substrates, heat-resistant tape substrates. , A toner stirrer film for printing, and a release film.

[Characteristics measurement method]
(1) Melting point or softening point of thermoplastic resin film a. Melting point (℃)
When a crystalline resin is used as the main component of the thermoplastic resin film, according to JIS K7121-1987, Seiko Instruments' DSC (RDC220) as a differential scanning calorimeter and its disk station (SSC / 5200) as a data analyzer. ) Is used to heat a weighed 3 mg sample from room temperature to 340 ° C. at a heating rate of 20 ° C./min on an aluminum pan, and at that time, the peak temperature of the endothermic peak of melting observed is measured. The measurement was carried out three times for one sample, and the average value of the obtained values was taken as the melting point (° C) of the sample.

b. Softening point (℃)
When an amorphous resin is used as the main component of the thermoplastic resin film, it is cut into a circle having a diameter of 5 mm to obtain a sample. This sample was heated in a thermomechanical analyzer (Hitachi High-Tech Science Co., Ltd., SS6100) using a cone-shaped needle probe with a tip diameter of 0.5 mm under a temperature rising condition of 10 ° C./min under a load of 49 mN, The softening point is measured from the plot of the probe penetration and the heating temperature. The measurement was performed three times for one sample, and the average value of the obtained values was used as the softening point (° C) of the sample.

(2) Layer Thickness and Layer Structure of Each Layer Constituting Thermoplastic Resin Film A thermoplastic resin film fixed on a sample stage of a scanning electron microscope was used for a decompression degree of 10 ⁻³ Torr, voltage 0.25 KV, current using a sputtering device. After ion etching treatment was performed for 10 minutes under the condition of 12.5 mA to cut a cross section, gold sputtering was performed on the surface with the same device, and the surface was observed with a scanning electron microscope at a magnification of 1000 times, and heat was applied. An image is taken so that the entire thickness direction of the plastic resin film can be observed. The thickness of the thermoplastic resin film was measured from the image obtained by observation.
When the entire thickness direction of the thermoplastic resin film cannot be confirmed at the above magnification, several images are taken in the thickness direction, and the images are stitched together to confirm the whole image. Samples used for measuring the thickness were selected at a total of 10 places, and the average of the measured values of the 10 samples was used as the film thickness of the sample and the thickness of the layers constituting the film.

(3) Particle diameter of 5, 50, 90% of particle concentration and cumulative distribution of layer (I) a. After confirming the thickness of each layer of the thermoplastic resin film using the method of particle concentration (2), a desired layer in the thermoplastic resin film is scraped off using a microplane within a range not exceeding the thickness. The scraped sample is put into a weighed crucible and then weighed again to weigh the sample before heating. Next, the crucible containing the sample is heated at 500 ° C./6 h in a muffle furnace (manufactured by Yamato Scientific Co., Ltd.) to incinerate the sample. After the crucible was cooled, it was weighed, the weight after heating was measured, and the weight before and after heating was inserted into the following formula to calculate the concentration of particles contained in the film. The measurement was performed at n = 3, and the average value was used as the particle concentration of the sample. Further, the sample amount was adjusted so that the mass of the residual material was in the range of 100 to 200 mg.
Particle concentration (mass%) = weight after heating (mg) / weight before heating (mg) × 100.

b. Particle size of 5, 50, 90% of cumulative distribution a. The residue obtained in step 1 was mixed with purified water, and the transmittance was adjusted to about 90%. This dispersion was subjected to ultrasonic treatment for 4 minutes before measurement under the conditions of a laser light wavelength of 780 nm and a measurement temperature of 25 ° C. using a laser light diffraction / scattering particle size distribution analyzer (Microtrac MT3000, manufactured by Nikkiso Co., Ltd.). The particle diameter (D5, D50, D90) of 5%, 50%, and 90% of the cumulative distribution was determined from the particle size distribution of the sample, which was measured according to JIS Z8825-1: 2001.

(4) Porosity (%) of layer (I)
A sample fixed on a sample stage of a scanning electron microscope was used under the conditions of a decompression degree of 10 ⁻³ Torr, a voltage of 0.25 KV, and a current of 12.5 mA by using a sputtering device so that a cross section perpendicular to the surface of the film can be seen. After 10 minutes of ion etching treatment to cut the cross section, gold sputtering was applied to the surface with the same apparatus, and the surface was observed at a magnification of 2000 using a scanning electron microscope. The obtained observation image was binarized by using image analysis software (MacView ver4.0, manufactured by Mountech Co., Ltd.) so that the resin portion was white and the void portions were black. On the other hand, the intensity is taken and the distribution is graphed. Regarding this density distribution, the point where the intensity of the density turned to increase was discriminated as the interface, and the layer (I) having pores and the other layer (II) were distinguished. The area A (μm ² ) of the hole portion and the total area B (μm ² ) of the layer in the observation image of the layer (I) having holes in the observation image were calculated using an image analyzer. Then, the porosity C (%) of the layer (I) was determined by applying the following formula. The evaluation was carried out at 5 points in each of two directions, that is, the arbitrary direction of the film and the direction perpendicular thereto, and a total of 10 observation images were taken and the porosity was calculated, and the average of 10 points was taken as the layer (I). Porosity (%).
Porosity C (%) of layer X = area A (μm ² ) of the void portion in the layer / total area B (μm ² ) of the layer × 100.

(5) Number of holes having a minimum circumscribed circle diameter (R) of 2 μm or less contained in a cross section 2500 μm ² perpendicular to the surface of the layer (I) The sample was fixed on a sample stage of a scanning electron microscope. The sample was subjected to ion etching treatment for 10 minutes under the conditions of a pressure reduction degree of 10 ⁻³ Torr, a voltage of 0.25 KV, and a current of 12.5 mA using a sputtering device so that a cross section with the thickness direction as a normal direction can be seen. After cutting the cross section, the surface is subjected to gold sputtering with the same apparatus, and a cross-sectional photograph of 2,000 times the cross section of the above sample is taken using a scanning electron microscope SEM. Trimming is performed from the above photograph so that it becomes an image containing only layer (I), and the cavities contained in the image are cross-sectional projection images using image analysis software (MacView ver4.0 manufactured by Mountech Co., Ltd.) It was created. The diameter (R) of the minimum circumscribed circle was calculated for all the holes included in the projected image of the cross section, and the number of holes having a diameter of 2 μm or less was extracted and the number was calculated. The evaluation was carried out at 5 points in each of two directions, that is, the arbitrary direction of the film and the direction orthogonal thereto, and the average value of the number of holes obtained from the evaluation of a total of 10 points was taken as the number of the above-mentioned holes of the sample. did.

(6) 200 μm equivalent edge tear resistance (N / 20 mm)
Evaluation is performed according to JIS C2151 (1990). The sample is sampled in a width of 20 mm and a length of 300 mm, and then, in an atmosphere of 23 ° C. and 65% RH, an electronic micrometer (manufactured by Anritsu Co., Ltd., K-312A type, needle pressure 30 g) is used to sample three arbitrary positions. The thickness was measured, and the average value was used as the thickness (μm) of the sample. Next, using the test fitting B (V-shaped notch type), the measurement was performed under the conditions of a pulling rate of 200 mm / min and 23 ° C. Since the edge tear resistance is proportional to the thickness, the measured value and the thickness were inserted into the following formula to obtain the edge tear resistance in terms of 100 μm.
Edge tear resistance in terms of 100 μm (N / 20 mm) = measured value of each sample (N / 20 mm) / thickness (μm) × 200 (μm)
The measurement was carried out on 10 sheets each in an arbitrary direction of the film and a direction orthogonal thereto, and the numerical value obtained by the arithmetic mean was taken as a 200 μm-converted end tear resistance (N / 20 mm) of the sample.

(7) A heat-resistant thermoplastic resin film was cut into a test piece having a width of 10 mm and a length of 250 mm in each direction of the film and in a direction perpendicular to the film, to obtain a test piece, and the test piece was heated in a hot air oven set to a temperature of 200 ° C. for 1000 hours. A heat treatment was performed, the elongation at break before and after the heat treatment was measured, the elongation retention rate was calculated from the following formula, and evaluated according to the following criteria. The breaking elongation is set in accordance with the method specified in JIS-C2151 using a Tensilon tensile tester so that a sample piece having a width of 10 mm is set to have a chuck length of 100 mm, and a tensile test is performed at a tensile speed of 300 mm / min. .. The evaluation was performed 10 times in each direction, the average value was obtained, and the evaluation was performed according to the following criteria.

Elongation retention rate (%) = Y / Y0 × 100
Y0: Elongation at break before heat treatment (%)
Y: Elongation at break after heat treatment (%)
A: Elongation retention rate is 80% or more B: Elongation retention rate is 50% or more and less than 80% C: Elongation retention rate is less than 50%.

(8) Dielectric constant The dielectric constant is measured by a cavity resonator perturbation method at a frequency of 10 GHz using a dielectric material measuring device (manufactured by Kanto Electronics Application Development Co., Ltd.). A sample cut out in the lateral direction of the film of 2.7 mm × the longitudinal direction of the film of 45 mm was inserted into the cavity resonator, and the measurement was performed under the environment of the temperature of 23 ° C. and the humidity of 65% RH. The measurement was performed at n = 3, the average value of the obtained values was calculated, and evaluated according to the following criteria.
A: Dielectric constant is 2.5 or less B: Dielectric constant is greater than 2.5 and 2.8 or less C: Dielectric constant is greater than 2.8.

(9) Electrical characteristics (transmission loss)
A circuit board adhesive AW-32 (manufactured by Kyodo Chemical Co., Ltd.) was applied to both surfaces of the thermoplastic resin film in a solidified thickness of 2 μm, and then 12 μm copper foil (3EC-HTE, manufactured by Mitsui Metal Industry Co., Ltd.) Was laminated on both surfaces by pressing at a pressure of 4 MPa for 10 minutes with a vacuum hot press machine heated to 170 ° C. to produce a laminate having a structure of copper foil / thermoplastic resin film / copper foil. A microstrip line having a wiring width of 140 μm and a length of 100 mm was formed as a circuit pattern on the copper foil surface of the obtained laminate by a chemical etching method to obtain a sample for evaluation. Immediately after leaving the above sample at a temperature of 23 ° C. and a humidity of 65% RH for 24 hours, immediately after using a network analyzer (Agilent Technology “8722ES”) and Cascade Microtech probe (ACP40-250), a 10-40 GHz The transmission loss (dB / 100 mm) was measured, and its absolute value (dB / 100 mm) was evaluated according to the following criteria.
A: Absolute value of transmission loss is less than 15 dB / 100 mm B: Absolute value of transmission loss is 15 dB / 100 mm or more and less than 25 dB / 100 mm C: Absolute value of transmission loss is 25 dB / 100 mm or more.
(10) Workability Using a motor slot processing machine (Odawara Engineering Co., Ltd.), the sample was processed into a slot shape with a width of 20 mm and a length of 40 mm at a processing speed of 2 pieces / second, and the processed sample was visually confirmed. The sample with deformation and tear was regarded as a defective product, and the defective product occurrence rate was evaluated according to the following criteria. The number of processed samples is 100 for each sample.
AA: Occurrence of defective rate is less than 15% A: Occurrence of defective rate is 15% or more and less than 25% B: Occurrence of defective rate is 25% or more and less than 40% C: Occurrence of defective rate is 40% or more.

(11) Productivity The film formation described in Examples and Comparative Examples was continuously performed for 10 hours, and the number of occurrences of film breakage (including breakage during longitudinal stretching and transverse stretching, heat setting treatment) was as follows. The productivity was confirmed by judging according to the standard.
A: No tear
B: Breakage frequency is 1 to 5 times C: Breakage frequency is 6 times or more
(12) Presence or absence of stretching (contractibility)
A 10 cm × 10 cm sample is cut out from an arbitrary portion of the thermoplastic resin film in an arbitrary direction, and the lengths of four sides are measured with a caliper. After that, it is sandwiched between polyimide films (manufactured by Toray DuPont Co., Ltd., 25 μm), heated in an oven at 250 ° C./1 h, taken out and cooled, and then the lengths of the four sides of the sample are measured again with a caliper, and the shrinkage rate of each of the four sides is measured. Was applied to the following formula.
Shrinkage (%) = (length of side before heating−length of side after heating) / length of side before heating × 100
The measurement was performed at n = 5, and the average of the shrinkage rates in the longitudinal and lateral directions of the cut out sample was obtained and evaluated according to the following criteria.
Unstretched: Shrinkage is less than 1% in both longitudinal and transverse directions Uniaxial stretching: Shrinkage is 1% or more in either longitudinal or transverse direction Biaxial stretching: Shrinkage is 1% or more in both longitudinal and transverse directions

(Reference Example 1) Method for producing polyphenylene sulfide resin (granule) 100 mol of sodium sulfide nonahydrate, 45 mol of sodium acetate and 25 liter of N-methyl-2-pyrrolidone were added to an autoclave (maximum working pressure: 14 MPa). (Hereinafter, abbreviated as NMP.) Was charged, the temperature was gradually raised to 220 ° C. with stirring, and the contained water was removed by distillation. 100 mol of p-dichlorobenzene was added as a main component monomer together with 5 liters of NMP into the system after the dehydration, and nitrogen was pressurized at 3 kg / cm ² at a temperature of 170 ° C. and then heated to 270. Polymerization was carried out at a temperature of ° C for 4 hours. After the completion of the polymerization, the mixture was cooled, the polymer was precipitated in distilled water, and a small block polymer was collected by a wire net having a 150 mesh opening. The small block polymer thus obtained was washed twice with distilled water at 90 ° C., then washed three times with an aqueous solution of sodium acetate, then once with distilled water, and dried at a temperature of 120 ° C. under reduced pressure. Thus, polyphenylene sulfide (PPS) resin granules having a melting point of 280 ° C. were obtained.

(Reference Example 2) Method for producing raw material for film (PPS1) The granules of the PPS resin produced in Reference Example 1 were mixed with a vented co-rotating twin-screw kneading extruder (manufactured by Japan Steel Works, screw). Diameter 30 mm, screw length / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged into strands, and cooled with water at a temperature of 25 ° C., Immediately cutting was carried out to produce a chip, which was used as a film raw material (PPS1).

(Reference Example 3) Method for producing film raw material (PPS2) As silica particles, FE9 (D50 = 6.1 μm, D5 = 0.7 μm, D90 = 11.0 μm) manufactured by Admatechs Co., Ltd. and SOC2 (D50 = D50 = manufactured by Admatechs Co., Ltd.) 0.5 μm, D5 = 0.1 μm, D90 = 1.1 μm) and FED (D50 = 22 μm, D5 = 8.3 μm, D90 = 80.2 μm) manufactured by Admatechs Co., Ltd., D50 = 6.1 μm, D5 = 0 It was blended so that Dμ was 0.6 μm and D90 was 23.0 μm. Next, 85% by mass of PPS resin granules and 15% by mass of a blend sample of the above silica particles as inorganic particles were used in a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter). 30 mm, screw length / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged into strands, cooled with water at a temperature of 25 ° C., and immediately thereafter. A chip was produced by cutting and used as a film raw material (PPS2).

(Reference Example 4) Method for producing raw material for film (PPS3) A film was prepared in the same manner as in Reference Example 3 except that 70% by mass of PPS resin granules and 30% by mass of a blend sample of silica particles prepared in Reference Example 3 were blended. A raw material (PPS3) was obtained.

(Reference Example 5) Method for producing raw material for film (PPS4) A film was prepared in the same manner as in Reference Example 3 except that 55% by mass of PPS resin granules and 45% by mass of a blend sample of silica particles prepared in Reference Example 3 were blended. A raw material (PPS4) was obtained.

(Reference Example 6) Method for producing raw material for film (PPS5) FE9 (D50 = 6.1 μm, D5 = 0.7 μm, D90 = 11.0 μm) manufactured by Admatechs Co., Ltd. as silica particles and SOC2 (D50 = D50 = manufactured by Admatechs Co., Ltd.) 0.5 μm, D5 = 0.1 μm, D90 = 1.1 μm) and FED (D50 = 22 μm, D5 = 8.3 μm, D90 = 80.2 μm) manufactured by Admatechs Co., Ltd., D50 = 6.1 μm, D5 = 0 It was blended so that D6 = 0.6 μm and D90 = 23 μm. Next, the above blended sample and water were mixed at a ratio of 1: 7, and stirred for 10 minutes using a magnetic stirrer. Then, the stirring is stopped and the mixture is allowed to stand for 30 minutes, and then 10 wt% of the initial weight of the supernatant containing fine particles is removed. Then, the particle size distribution of the stirred dispersion is measured again using a stirrer. After repeating this operation until D5 = 0.8 μm, the solution was left standing for 24 hours to completely settle the particles, and the supernatant water was removed as much as possible. After drying at 24 ° C. for 24 hours, water was removed to obtain silica particles having a controlled particle size distribution. The particle size of the obtained particles was D50 = 6.2 μm, D5 = 0.8 μm, and D90 = 22.9 μm.
Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared as a raw material for film (PPS5).

(Reference Example 7) Method for producing raw material for film (PPS6) As silica particles, FE9 (D50 = 6.1 μm, D5 = 0.7 μm, D90 = 11.0 μm) manufactured by Admatechs Co., Ltd. and SOC2 (D50 = D50 = manufactured by Admatechs Co., Ltd.) 0.5 μm, D5 = 0.1 μm, D90 = 1.1 μm) and FEB manufactured by Admatechs (D50 = 12.3 μm, D5 = 2.5 μm, D90 = 20.1 μm) were D50 = 6.0 μm, D5. = 0.6 μm and D90 = 14.0 μm. Next, the above blended sample and water were mixed at a ratio of 1: 7, and stirred for 10 minutes using a magnetic stirrer. Then, the stirring is stopped and the mixture is allowed to stand for 30 minutes, and then 10 wt% of the initial weight of the supernatant containing fine particles is removed. Then, the particle size distribution of the stirred dispersion is measured again using a stirrer. After repeating this operation until D5 = 0.8 μm, the solution was left standing for 24 hours to completely settle the particles, and the supernatant water was removed as much as possible. After drying at 24 ° C. for 24 hours, water was removed to obtain silica particles having a controlled particle size distribution. The particle size of the obtained particles was D50 = 6.1 μm, D5 = 0.8 μm, and D90 = 14.2 μm.

  Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared as a raw material for film (PPS6).

(Reference Example 8) Production method of raw material for film (PPS7) FE9 (D50 = 6.1 μm, D5 = 0.7 μm, D90 = 11.0 μm) manufactured by Admatechs Co., Ltd. as silica particles and water in a ratio of 1: 7. It mixed and stirred for 10 minutes using the magnetic stirrer. Then, the stirring is stopped and the mixture is allowed to stand for 30 minutes, and then 10 wt% of the initial weight of the supernatant containing fine particles is removed. Then, the particle size distribution of the stirred dispersion is measured again using a stirrer. After repeating this operation until D5 = 0.8 μm, the solution was left standing for 24 hours to completely settle the particles, and the supernatant water was removed as much as possible. After drying at 24 ° C. for 24 hours, water was removed to obtain silica particles having a controlled particle size distribution. The particle size of the obtained particles was D50 = 6.1 μm, D5 = 0.8 μm, and D90 = 11.3 μm.

  Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared as a raw material for film (PPS7).

(Reference Example 9) Method for producing raw material for film (PPS8) As silica particles, SOC2 (D50 = 0.5 μm, D5 = 0.1 μm, D90 = 1.1 μm) manufactured by Admatechs and FED (D50 = D50 = manufactured by Admatechs) 22 μm, D5 = 8.3 μm, D90 = 80.2 μm) were blended so that D50 = 13.0 μm, D5 = 0.6 μm, D90 = 31.0 μm. Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared as a raw material for film (PPS8).

(Reference Example 10) Production method of raw material for film (PPS9) SC5500 (D50 = 1.5 μm, D5 = 0.3 μm, D90 = 3.0 μm) manufactured by Admatechs Co., Ltd. as silica particles and water at a ratio of 1: 7. It mixed and stirred for 10 minutes using the magnetic stirrer. Then, the stirring is stopped and the mixture is allowed to stand for 30 minutes, and then 10 wt% of the initial weight of the supernatant containing fine particles is removed. Then, the particle size distribution of the stirred dispersion is measured again using a stirrer. After repeating this operation until D5 = 0.6 μm, the solution was left standing for 24 hours to completely settle the particles, and then the supernatant water was removed as much as possible, and the remaining slurry-like particles were spread on a vat. After drying at 24 ° C. for 24 hours, water was removed to obtain silica particles having a controlled particle size distribution. The particle size of the obtained particles was D50 = 1.6 μm, D5 = 0.6 μm, and D90 = 3.1 μm.

  Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared as a raw material for film (PPS9).

(Reference Example 11) Production method of raw material for film (PPS10) P-10 (D50 = 3.4 μm, D5 = 0.5 μm, D90 = 12.0 μm) manufactured by Shiraishi Industry Co., Ltd. as calcium carbonate and water 1: 7. The mixture was mixed at a ratio and stirred for 10 minutes using a magnetic stirrer. Then, the stirring is stopped and the mixture is allowed to stand for 30 minutes, and then 10 wt% of the initial weight of the supernatant containing fine particles is removed. Then, the particle size distribution of the stirred dispersion is measured again using a stirrer. After repeating this operation until D5 = 0.8 μm, the solution was left standing for 24 hours to completely settle the particles, and the supernatant water was removed as much as possible. Water was removed by drying at 24 ° C. for 24 hours to obtain calcium carbonate particles having a controlled particle size distribution. The particle size of the obtained particles was D50 = 3.5 μm, D5 = 0.8 μm, and D90 = 12.5.1 μm.

  Next, 70% by mass of PPS resin granules and 30% by mass of the above calcium carbonate particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw) (Length / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut. Chips were produced and used as a film raw material (PPS10).

(Reference Example 12) Manufacturing method of raw material for film (PEEK1) FE9 manufactured by Admatechs Co., Ltd. as silica particles was analyzed in the same manner as in Reference Example 8 to obtain a particle size distribution of D50 = 6.1 μm, D5 = 0.8 μm, D90 = 11.3 μm. I adjusted it to be. Next, a PEEK resin having a melting point of 340 ° C. (90 G, manufactured by Victorex Co.) and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 360 ° C. (manufactured by Japan Steel Works) , Screw diameter 30 mm, screw length / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged into strands, and cooled with water at a temperature of 25 ° C. After that, cutting was immediately performed to produce a chip, which was used as a film raw material (PEEK1).

(Reference Example 13) Production method of raw material for film (PEI1) FE9 manufactured by Admatechs Co., Ltd. was used as silica particles in the same manner as in Reference Example 8 to obtain a particle size distribution of D50 = 6.1 μm, D5 = 0.8 μm, D90 = 11.3 μm. I adjusted it to be. Next, a PEI resin having a softening point of 340 ° C. (ULTEM1010, manufactured by SAVIC Innovative Plastics Co., Ltd.) and 30% by mass of the above silica particles were blended, and the twin-screw kneading extruder of the same direction with a vent heated to 350 ° C. (Japan Steel mill, screw diameter 30 mm, screw length / screw diameter = 45.5), and melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute and discharged in strands, and water at a temperature of 25 ° C. After cooling with, the chip was immediately cut to prepare a chip, which was used as a film raw material (PEI1).

(Reference Example 14) Production method of raw material for film (PPS11) A film was prepared in the same manner as in Reference Example 3 except that 95% by mass of PPS resin granules and 5% by mass of a blend sample of silica particles prepared in Reference Example 3 were blended. A raw material (PPS11) was obtained.
Reference Example 15 Production Method of Raw Material for Film (PPS12) As a silica particle, SS03 manufactured by Osaka Kasei Co., Ltd. was used, and the particle size distribution was D50 = 0.3 μm, D5 = 0.1 μm, D90 = 1. It was adjusted to be 0 μm. Next, 70% by mass of PPS resin granules and 30% by mass of the above silica particles were blended, and a co-rotating twin-screw kneading extruder with a vent heated to 320 ° C. (manufactured by Japan Steel Works, screw diameter 30 mm, screw length) S / screw diameter = 45.5), melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips. Was prepared to obtain a film raw material (PPS12).

Reference Example 16 Production Method of Raw Material for Film (PEN1) FE9 manufactured by Admatechs Co., Ltd. was used as silica particles in the same manner as in Reference Example 8 to obtain a particle size distribution of D50 = 6.1 μm, D5 = 0.8 μm, D90 = 11.3 μm. I adjusted it to be. To a mixture of 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate and 60 parts by weight of ethylene glycol, 0.03 parts by weight of manganese acetate tetrahydrate salt was added, and the temperature was gradually increased from 150 ° C to 240 ° C. The transesterification reaction was performed while raising the temperature. On the way, when the reaction temperature reached 170 ° C., 0.024 part by weight of antimony trioxide was added. Further, when the reaction temperature reached 220 ° C., 0.042 parts by weight of tetrabutylphosphonium 3,5-dicarboxybenzenesulfonate (corresponding to 2 mmol%) was added. Then, a transesterification reaction was subsequently carried out, and after completion of the transesterification reaction, 0.023 part by weight of trimethyl phosphate was added. Then, the reaction product is transferred to a polymerization reactor, heated to a temperature of 290 ° C., and subjected to a polycondensation reaction under a high reduced pressure of 0.2 mmHg or less, a polyethylene having an intrinsic viscosity of 0.65 dl / g and a melting point of 265 ° C. A 2,6-naphthalate (PEN) chip was obtained. Further, FE9 manufactured by Admatechs Co., Ltd. as silica particles was adjusted in the same manner as in Reference Example 8 so that the particle size distribution was D50 = 6.1 μm, D5 = 0.8 μm, and D90 = 11.3 μm. 70% by mass of the above PEN chips and 30% by mass of the above silica particles were heated at 290 ° C. in a co-rotating twin-screw kneading extruder with a vent (manufactured by Japan Steel Works, screw diameter 30 mm, screw length / screw diameter = 45.5), and melt-extruded at a residence time of 90 seconds and a screw rotation speed of 150 rotations / minute, discharged in strands, cooled with water at a temperature of 25 ° C., and immediately cut into chips to form a film. It was used as a raw material (PEN1).

(Reference Example 17)
PPS1 shown in Reference Example 2 was prepared as the resin constituting the layers (I) and (II), and the respective raw materials were separately vacuum dried at 180 ° C. for 3 hours, and then two units heated to 320 ° C. Separately supplied to the extruder of the above, and in a molten state, three layers are formed by the laminating device on the upper part of the die (the laminating constitution is (I) / (II) / (I), the laminating ratio is (I) :( II) :( I) = 1: 8: 1), then ejected from a T-die type die, and then rapidly cooled and solidified while applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C. to obtain a 100 μm unstretched film. Got (Examples 1 to 9, Comparative Examples 1 and 2)
Raw materials having the formulations shown in Table 2 were prepared as the resins constituting the layers (I) and (II), and each of the raw materials was vacuum dried at 180 ° C. for 3 hours, and then two units heated to 320 ° C. were used. Separately supplied to the extruder and in a molten state, three layers were formed by a laminating device on the upper part of the die (the laminating constitution is (I) / (II) / (I), the laminating ratio is (I) :( II) :( I ) = 1: 8: 1), and then ejected from a T-die type die, and subjected to rapid cooling and solidification while applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C. to form an unstretched laminate of 550 μm. Got the sheet. Next, the obtained unstretched laminated sheet is preheated with a plurality of heating rolls heated to a surface temperature of 90 ° C., and then a heating roll heated to a surface temperature of 100 ° C. and a circumference provided next to the heating roll. The film was stretched 3.2 times in the longitudinal direction (MD direction) with a cooling roll of 30 ° C. having a different speed. The uniaxially stretched sheet thus obtained was stretched 3.0 times at a temperature of 95 ° C. in a longitudinal direction and a vertical direction (TD direction) using a tenter, followed by heat treatment at 255 ° C. and subsequently at 255 ° C. In the relaxation treatment zone, a 7% relaxation treatment was performed in the TD direction and then cooled to room temperature to obtain a PPS film having a thickness of 100 μm.

(Example 10)
A PEEK resin chip (90 G, manufactured by Victrex) having a melting point of 340 ° C. is used as a layer (II), and a PEEK1 chip obtained in Reference Example 12 is used as a layer (I) at 180 ° C. for 3 hours under vacuum drying. After that, they were separately supplied to two extruders heated to 360 ° C., and in a molten state, three layers were formed by a laminating device on the upper part of the die (the laminating constitution was (I) / (II) / (I), laminating The ratio is (I) :( II) :( I) = 1: 8: 1), and then discharged from the T-die type die, while applying an electrostatic charge to the cast drum with a surface temperature of 25 ° C. Adhesion was rapidly cooled and solidified to obtain an unstretched laminated sheet of 550 μm. Then, the obtained unstretched sheet was cut into a size of 100 mm × 100 mm, and a film stretcher (manufactured by Bruckner, KARO-IV) was used to preheat and stretch at 160 ° C. for a preheating time of 1 minute. At a stretching rate of 5% / sec, the sheet was sequentially stretched at a draw ratio of 3.0 times in the longitudinal (MD) direction and then 3.0 times in the transverse (TD) direction of the sheet, and then cooled to room temperature to have a thickness of 100 μm. Of PEEK film was obtained. (Example 11)
Chips of PEI resin (ULTEM1010, SAVIC Innovative Plastics Co., Ltd.) having a softening point of 340 ° C. are used for the layer (II), and chips of PEI1 obtained in Reference Example 13 are used for the layer (I) at 180 ° C. for 3 hours. After vacuum drying, they were separately fed to two extruders heated to 350 ° C., and in a molten state, three layers were formed by a laminating device on the upper part of the die (the laminating constitution is (I) / (II) / (I ), The stacking ratio is (I) :( II) :( I) = 1: 8: 1), then discharge from the T-die type die, and electrostatic charge is applied to the cast drum with a surface temperature of 25 ° C. While applying, it was contacted and rapidly solidified to obtain a 550 μm unstretched laminated sheet.
Then, the obtained unstretched sheet was cut into a size of 100 mm × 100 mm, and using a film stretcher (manufactured by Bruckner, KARO-IV), both preheating and stretching temperatures were 230 ° C. and a preheating time was 1 minute, Sequential stretching was performed at a stretching rate of 5% / sec in the longitudinal direction (MD) of the sheet at a stretching ratio of 3.0 times, and then in the transverse direction (TD) of the sheet at a sequential stretching ratio of 3.0 times, followed by heat treatment at 280 ° C. After that, it was cooled to room temperature to obtain a PEI film having a thickness of 1000 μm.

(Comparative example 3)
The PEN chip obtained in Reference Example 16 was used for the layer (II), and the PEN1 chip obtained in Reference Example 16 was used for the layer (I). After vacuum drying at 160 ° C. for 3 hours, each was heated to 290 ° C. Separately supplied to two extruders, and in a molten state, three layers were formed by the laminating device on the upper part of the die (the laminating constitution is (I) / (II) / (I), the laminating ratio is (I) :( II ) :( I) = 1: 8: 1), and then ejected from the T-die type die, and rapidly solidified by applying electrostatic charge to a cast drum having a surface temperature of 25 ° C. to rapidly solidify it at 550 μm. An unstretched laminated sheet was obtained. Then, the obtained unstretched laminated sheet is preheated by a plurality of heating rolls heated to a surface temperature of 130 ° C., and then a heating roll heated to a surface temperature of 100 ° C. and a circumference provided next to the heating roll. The film was stretched 3.0 times in the longitudinal direction (MD direction) with a cooling roll of 30 ° C. having a different speed. The uniaxially stretched sheet thus obtained was stretched 3.0 times at a temperature of 130 ° C. in a longitudinal direction and a vertical direction (TD direction) using a tenter, followed by heat treatment at 230 ° C. and then at 230 ° C. In the relaxation treatment zone, a relaxation treatment of 7% was performed in the TD direction, followed by cooling to room temperature to obtain a PEN film having a thickness of 100 μm.

Claims (8)

A thermoplastic resin film made of a thermoplastic resin having a melting point or a softening point of 270 ° C. or higher, having a laminated structure of two or more layers, and at least one of the constituent layers has a porosity of 20% or more (I). In the layer (I), the number of holes having a minimum circumscribed circle diameter R of 2 μm or less is 20 or less among the holes included in a cross section 2500 μm ² perpendicular to the surface of the thermoplastic resin film. A thermoplastic film. The thermoplastic resin film according to claim 1, wherein an average value of edge resistance in terms of 200 μm in an arbitrary direction of the film and a direction orthogonal thereto is 100 N / 20 mm or more. The thermoplastic resin film according to claim 1, which has a dielectric constant of 2.8 or less at a frequency of 10 GHz. The thermoplastic resin film according to claim 1, wherein the thickness of the thermoplastic resin film is 10 to 350 μm. The particles used in the layer (I) constituting the thermoplastic resin film have a ratio (D90 / D90) of 90% numerical value particle diameter (D90) and 50% numerical value particle diameter (D50) of the cumulative distribution obtained by particle size distribution measurement. The thermoplastic resin film according to claim 1, wherein D50) is 3.0 or less. The method for producing a thermoplastic resin film according to claim 1, wherein the respective layers forming the film are laminated by coextrusion. A circuit member using the thermoplastic resin film according to claim 1. The thermoplastic resin film according to claim 1, wherein the film is biaxially stretched.