resin film

Abstract

To provide a resin film which achieves high heat resistance, low dielectric constant and low thermal expansion, and contains a polynorbornene resin as a main material.SOLUTION: A resin film 1 contains a polynorbornene resin as a main material, wherein the polynorbornene resin has a glass transition point of 200°C or higher, and the resin film 1 satisfies a coefficient of linear thermal expansion at a temperature lower than the glass transition point of 40 ppm / K or less. The resin film 1 preferably has a relative dielectric constant at a frequency of 10 GHz of 1.5 or more and 3.5 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a resin film. [Background technology]

[0002] In recent years, electronic devices have become more sophisticated and are increasingly used in mobile applications, leading to a particular trend towards faster communication speeds.

[0003] Consequently, the constituent materials of various components that make up electronic devices are required to satisfy various properties such as high heat resistance, low dielectric constant (Dk(-)), low dielectric loss tangent (Df(-)), and low thermal expansion coefficient.

[0004] Under these circumstances, it has been proposed to use a resin film made primarily of polynorbornene-based resin as a component of electronic devices (see, for example, Patent Document 1).

[0005] Polynorbornene-based resin The resin film, which is the main material, has attracted attention because it exhibits excellent properties in terms of high heat resistance and low dielectric constant. However, it has had a problem in that it tends to have a relatively high coefficient of thermal expansion. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2001-226494 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a resin film composed mainly of a polynorbornene-based resin that exhibits high heat resistance, low dielectric constant, and low thermal expansion coefficient. [Means for solving the problem]

[0008] Such an object is achieved by the present invention described in the following (1) to ( 4 ). (1) A resin film composed mainly of a polynorbornene-based resin, where the glass transition temperature of the polynorbornene-based resin is 200 °C or higher, and the linear thermal expansion coefficient of the resin film at a temperature below the glass transition temperature is 40 ppm / K or less the law of nature, The resin film is stretched in at least one of the MD and TD directions. The polynorbornene-based resin is oriented along the aforementioned one direction, The aforementioned polynorbornene-based resin is a copolymer represented by the following general formula (5Y). A resin film characterized by the above. [Chemical formula] [In the general formula (5Y) above, n and m are each independently an integer of 1 or more, and group X is one of the following: a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, or a glycidyl ether group.]

[0009] (2) The resin film according to (1) above, wherein the relative permittivity of the resin film at a frequency of 10 GHz is 1.5 or more and 3.5 or less.

[0010] (3) The resin film according to (1) above, wherein the dielectric loss tangent of the resin film at a frequency of 10 GHz is 1.0×10 -4 or more and 2.0×10 -3 or less.

[0011] (4) The resin film according to (1) above, wherein the average thickness of the resin film is 20 μm or more and 500 μm or less. [Advantages of the Invention]

[0015] According to the present invention, it can be said that not only high heat resistance and low dielectric constant are achieved by the excellent properties of the resin film composed mainly of a polynorbornene-based resin, but also low thermal expansion coefficient is achieved. [Brief Description of the Drawings]

[0016] [Figure 1]This is a longitudinal cross-sectional view showing an embodiment of the resin film of the present invention. [Figure 2] Figure 1 is a side view of a resin film manufacturing apparatus capable of producing the resin film shown. [Modes for carrying out the invention]

[0017] The resin film of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0018] <Resin film 1> Figure 1 is a longitudinal cross-sectional view showing an embodiment of the resin film of the present invention. In the following description, the upper side of Figure 1 will be referred to as "top" and the lower side as "bottom".

[0019] As shown in Figure 1, the resin film 1 (the resin film of the present invention) is in the form of a film (sheet) and is mainly composed of a polynorbornene-based resin. The polynorbornene-based resin has a glass transition temperature of 200°C or higher, and the resin film 1 satisfies the requirement that its linear thermal expansion coefficient below the glass transition temperature is 40 ppm / K or less.

[0020] Resin film 1, which is mainly composed of polynorbornene-based resin, is generally known to exhibit excellent heat resistance and to have a low dielectric constant. In particular, in the present invention, since the glass transition temperature of the polynorbornene-based resin contained therein is 200°C or higher, resin film 1 exhibits particularly excellent heat resistance, and furthermore, by applying the resin film 1 manufacturing method described later, the linear thermal expansion coefficient below the glass transition temperature of resin film 1 is 40 ppm / K or less, thus achieving a low thermal expansion coefficient.

[0021] The following describes this resin film 1. The resin film 1 is composed primarily of a polynorbornene-based resin.

[0022] Polynorbornene-based resins are a type of so-called high-Tg resin that exhibits a high Tg (high glass transition temperature). While not particularly limited, examples include those containing the structural unit shown in the following general formula (1Y), and among these, those with a glass transition temperature of 200°C or higher are selected. This ensures that a resin film 1 with particularly excellent heat resistance and low dielectric constant can be reliably obtained.

[0023] [ka]

[0024] In the general formula (1Y), R 1 ~R 4 Each of these is either hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, a glycidyl ether group, or one of the substituents (2Y) listed below. Also, m is an integer from 0 to 4.

[0025] [ka]

[0026] In the general formula (2Y), R 5 These are hydrogen, a methyl group, or an ethyl group, respectively, and R 6 , R 7 and R 8 n is one of the following: a linear or branched C1-C20 alkyl group, a linear or branched C1-C20 alkoxy group, a linear or branched C1-C20 alkylcarbonyloxy group, a linear or branched C1-C20 alkylperoxy group, or a substituted or unsubstituted C6-C20 aryloxy group. Also, n is an integer from 0 to 5.

[0027] The linear or branched alkyl group having 1 to 20 carbon atoms is not particularly limited, but examples include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, etc.

[0028] The aromatic group is not particularly limited, and examples thereof include a phenyl group, a phenethyl group, a naphthyl group, and the like.

[0029] The alicyclic group is not particularly limited, and examples thereof include an alicyclic group such as a cyclohexyl group, a norbornenyl group, a dihydrodicyclopentadienyl group, a tetracyclododecyl group, a methyltetracyclododecyl group, a tetracyclododecadienyl group, a dimethyltetracyclododecyl group, an ethyltetracyclododecyl group, an ethylidenyltetracyclododecyl group, a phenyltetracyclododecyl group, and a trimer of a cyclopentadienyl group.

[0030] R in the substituent (2Y) 5 is not particularly limited, and examples thereof include hydrogen, a methyl group, an ethyl group, and the like.

[0031] R in the substituent (2Y) 6 , R 7 and R 8 are each not particularly limited, and examples thereof include a linear or branched alkyl group having 1 to 20 carbon atoms, a linear or branched alkoxy group having 1 to 20 carbon atoms, a linear or branched alkylcarbonyloxy group having 1 to 20 carbon atoms, a linear or branched alkylperoxy group having 1 to 20 carbon atoms, and a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms.

[0032] Specific examples of such substituents include, for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, an acetoxy group, a propionyloxy group, a butyryloxy group, a methylperoxy group, an isopropylperoxy group, a t-butylperoxy group, a phenoxy group, a hydroxyphenoxy group, a naphthyloxy group, and the like.

[0033] In addition, m in the general formula (1Y) is an integer of 0 to 4, and is not particularly limited, but 0 or 1 is preferable. When m is 0 or 1, the structural unit represented by the general formula (1Y) is represented by the following general formula (3Y) or (4Y).

[0034] [ka]

[0035] [ka]

[0036] From the above, the structural unit represented by the general formula (1Y) can be specifically obtained by polymerizing norbornene monomers such as norbornene, 5-methylnorbornene, 5-ethylnorbornene, 5-propylnorbornene, 5-butylnorbornene, 5-pentylnorbornene, 5-hexylnorbornene, 5-heptylnorbornene, 5-octylnorbornene, 5-nonylnorbornene, 5-decylnorbornene, 5-ethylidene-2-norbornene, cyclohexanenorbornene, 5-phenethylnorbornene, 5-triethoxysilylnorbornene, 5-trimethylsilylnorbornene, 5-trimethoxysilylnorbornene, 5-methyldimethoxysilylnorbornene, 5-dimethylmethoxynorbornene, and 5-glycidyloxymethylnorbornene. Furthermore, when polymerizing the norbornene monomer, polymerization may be carried out using a single norbornene monomer, or copolymerization may be carried out using multiple norbornene monomers.

[0037] Such polynorbornene-based resins may be monopolymers formed from a single structural unit represented by the general formula (1Y), or copolymers formed from multiple structural units. Of these, in the present invention, those with a glass transition temperature (Tg) of 200°C or higher are selected, and specifically, copolymers represented by the following general formula (5Y) are preferred. This ensures that polynorbornene-based resins exhibiting a glass transition temperature of 200°C or higher are reliably selected.

[0038] [ka]

[0039] In the general formula (5Y) above, n and m are each independently an integer of 1 or more, and group X is one of the following: a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, or a glycidyl ether group.

[0040] Polynorbornene-based resins (PNB resins) having the structural unit represented by the general formula (5Y) include, as specific examples, copolymers such as norbornene-hexylnorbornene copolymer, norbornene-ethylidenenorbornene copolymer, norbornene-cyclohexanenorbornene copolymer, norbornene-triethoxysilylnorbornene copolymer, norbornene-glycidyloxymethylnorbornene copolymer, butylnorbornene-triethoxysilylnorbornene copolymer, decylnorbornene-triethoxysilylnorbornene copolymer, butylnorbornene-glycidyloxymethylnorbornene copolymer, and decylnorbornene-glycidyloxymethylnorbornene copolymer.

[0041] Furthermore, the polynorbornene-based resin having the structural unit represented by the general formula (5Y) preferably has a weight-average molecular weight (Mw) of 50,000 g / mol or more and 1,000,000 g / mol or less, and more preferably 100,000 g / mol or more and 500,000 g / mol or less. By applying the method for manufacturing the resin film 1 described later, the polynorbornene-based resin can be oriented in the resin film 1, and its linear thermal expansion coefficient below the glass transition temperature can be reliably set to 40 ppm / K or less. The weight-average molecular weight (Mw) can be obtained by creating a calibration curve for a polystyrene standard substance using gel permeation chromatography (GPC) and calculating the weight-average molecular weight (Mw) using this calibration curve.

[0042] Such polynorbornene-based resins are acceptable as long as their glass transition temperature is 200°C or higher, but preferably 280°C or higher, and more preferably 300°C to 340°C. This allows the resin film 1 to exhibit superior heat resistance, i.e., to have higher heat resistance. Furthermore, even when using a resin film 1 containing such a high Tg polynorbornene-based resin, by applying the resin film 1 manufacturing method described later, the resulting resin film 1 can be made in which the occurrence of yellowing and curling associated with the low molecular weight of the polynorbornene-based resin can be effectively suppressed or prevented. In other words, the resin film 1 can be reliably made to have excellent transparency and excellent flatness.

[0043] Furthermore, the resin film 1 containing polynorbornene-based resin as the main material only needs to have a linear thermal expansion coefficient (CTE) of 40 ppm / K or less below the glass transition temperature (Tg) of the polynorbornene-based resin, but it is preferable that it be set to 15 ppm / K or more and 30 ppm / K or less. This can be said to have achieved a low thermal expansion coefficient for the formed resin film 1. In addition, by manufacturing the resin film 1 using the manufacturing method for the resin film 1 described later, the polynorbornene-based resin can be oriented in the resin film 1, and its linear thermal expansion coefficient below the glass transition temperature can be reliably set to the upper limit value or less. Here, the linear thermal expansion coefficient (CTE) of polynorbornene-based resin below the Tg can be calculated, for example, by preparing a test piece (width 10 mm × length 10 mm) made of the resin film 1, extracting the normal strain in the stretching direction of the test piece during the heating process from 50 to 150°C using the digital image correlation method, and calculating it from the slope of the straight line obtained by linearly approximating the normal strain as a function of temperature.

[0044] Furthermore, by incorporating a polynorbornene-based resin as the main material, the dielectric constant of the resin film 1 can be reduced. Specifically, the relative permittivity (Dk(-)) of the resin film 1 at a frequency of 10 GHz can be set to a range of preferably 1.5 to 3.5, more preferably 2.0 to 3.0. Also, the dielectric loss tangent (Df(-)) at a frequency of 10 GHz can be set to a range of preferably 0.00010 to 0.00200, more preferably 0.00020 to 0.00100.

[0045] Furthermore, the relative permittivity (Dk(-)) and dielectric loss tangent (Df(-)) of the resin film 1 can be measured using a dielectric constant measuring device based on the cavity resonator method in accordance with JIS C 2526.

[0046] The resin film 1 only needs to contain polynorbornene-based resin as its main material; that is, it only needs to contain 50% by weight or more of polynorbornene-based resin, and may also contain additives as other constituent materials. Examples of such additives include antioxidants, lubricants, ultraviolet absorbers, flame retardants, and stabilizers.

[0047] Furthermore, if the polynorbornene resin has a structural unit represented by the general formula (1Y), its synthesis can be carried out, for example, by ring-opening metathesis polymerization (hereinafter also referred to as ROMP), a combination of ROMP and hydrogenation reaction, or polymerization by radicals or cationic agents.

[0048] More specifically, polynorbornene resins having the structural unit represented by the general formula (1Y) can be synthesized, for example, by using a catalyst containing a palladium ion source, a catalyst containing nickel and platinum, a radical initiator, and the like.

[0049] <Method for manufacturing resin film 1> The resin film 1 (the resin film of the present invention) having the above configuration is manufactured (molded) by applying the resin film manufacturing method shown below.

[0050] Before describing the resin film manufacturing method, the following section will first describe the resin film manufacturing apparatus to which this method is applied.

[0051] (Resin film manufacturing equipment) Figure 2 is a side view of a resin film manufacturing apparatus capable of producing the resin film shown in Figure 1. In the following explanation, the upper part of Figure 2 will be referred to as "top" and the lower part as "bottom".

[0052] The resin film manufacturing apparatus 500 shown in Figure 2 includes a film supply unit 700, a film molding unit 800, a film drying unit 600, and a film transport unit 400.

[0053] The film supply unit 700 comprises an extruder 210, a T-die 240, and a single-screw or twin-screw multi-screw kneader 230. The kneader 230 is connected to a pipe 212 connected to the extruder 210, and the T-die 240 is further connected to the kneader 230 via the pipe 212.

[0054] In the film supply unit 700 with this configuration, a resin composition mainly composed of a polynorbornene-based resin for forming the resin film 1 is stored in the extruder 210. When the resin composition stored in the extruder 210, which is in a molten or softened state, is supplied to the kneader 230, the kneader 230 operates and kneads it in a molten or softened state. Subsequently, the molten or softened resin composition is supplied to the film molding unit 800 as a molten film 150, which is in the form of a film, via the kneader 230, piping 212, and the T-die 240 (and its opening 241).

[0055] The film forming section 800 has three touch rolls 110, 120, and 130. Each of these rolls is configured to rotate independently by a motor (driving means) (not shown) and is made of a metal material such as stainless steel. Furthermore, the rotation axes (central axes) of these rolls are aligned in the same direction and are spaced apart from each other. In addition, each roll is rotatably supported by a frame (not shown) that supports the entire resin film manufacturing apparatus 500.

[0056] Furthermore, at least one of these touch rolls 110 to 130 is equipped with a heating means, thereby enabling the heating of a film-like molten film 150, i.e., a resin composition in a molten or softened state.

[0057] The rotation of these touch rolls 110, 120, and 130 causes the molten film 150 supplied from the film supply unit 700 to be continuously fed out. By continuously feeding the molten or softened molten film 150 into this film forming unit 800, the first surface 15 and the second surface 13 of the molten film 150 are flattened, and the thickness of the molten film 150 is set to a desired size.

[0058] Touch roll 110 and touch roll 120 are rolls with smooth outer surfaces and are arranged facing each other. By supplying molten film 150 between touch roll 110 and touch roll 120, the first surface 15 and the second surface 13 of the molten film 150 are flattened.

[0059] Furthermore, the touch roll 130 is a roll with a smooth outer surface and is positioned downstream of the touch rolls 110 and 120. By supplying the molten film 150 to such a touch roll 130, the second surface 13 of the molten film 150 is further flattened.

[0060] Furthermore, by appropriately setting the separation distance between touch roll 110 and touch roll 120, and the separation distance between touch roll 120 and touch roll 130, a molten film 150 of a desired thickness can be obtained.

[0061] Then, the first surface 15 and the second surface 13 are flattened by the touch rolls 110-130 equipped with heating means, and the molten film 150, whose thickness is set to a predetermined size, is heated, thereby removing a portion of the solvent contained in the molten film 150.

[0062] The film transport unit 400 has a plurality of transport rollers 41 that transport (supply) the molten film 150 sent from the film molding unit 800 to the film drying unit 600 and discharge the resin film 1 from the film drying unit 600, and a winding roller 46 that winds (winds) the resin film 1 discharged from the film drying unit 600.

[0063] Each roller is configured to rotate independently by a motor (driving means) (not shown), and is made of a metal material such as stainless steel. Furthermore, the rotation axes (central axes) of these rollers are aligned in the same direction and are spaced apart from each other. Each roller is also rotatably supported by a frame (not shown) that supports the entire resin film manufacturing apparatus 500.

[0064] Each of the conveying rollers 41 has a cylindrical outer shape. These conveying rollers 41 rotate while the middle of the molten film 150 (resin film 1) in the longitudinal direction is in contact with the second surface 13 (bottom surface). This allows the molten film 150 fed from the film molding section 800 (touch roll 130) to be transported (supplied) to the film drying section 600, and the resin film 1 dried in the film drying section 600 to be discharged from the film drying section 600.

[0065] Furthermore, the winding roller 46 has a cylindrical shape and is located at the downstream end in the conveying direction of the resin film 1. It is a roller that winds up the resin film 1 that has been fed out from the film drying section 600, i.e., the upstream side in the conveying direction. The rotation of this winding roller 46 causes the resin film 1 to be wound onto the winding roller 46.

[0066] Furthermore, the conveying speed of the molten film 150 by the conveying roller 41 and the winding speed of the resin film 1 by the winding roller 46 are set faster than the conveying speed of the molten film 150 by the touch rolls 110-130. As a result, when the molten film 150 (resin film 1) is conveyed between the touch roll 130 and the winding roller 46, a tension acts on the molten film 150 that stretches it in the MD (flow direction). Therefore, the molten film 150 is stretched along the MD (flow direction). Consequently, the resin film 1, which has been stretched along the MD, is wound onto the winding roller 46.

[0067] The film drying section 600 has a pair of hot air supply units 61. These hot air supply units 61 are located between the two transport rollers 41, downstream of the film forming section 800 (touch roll 130) in the transport direction of the molten film 150, with one above and one below the molten film 150, and are supported and fixed to the frame that supports the entire resin film manufacturing apparatus 500. Each hot air supply unit 61 has a built-in heating unit (heating fan) (not shown), and the hot air heated by this heating unit is blown onto the molten film 150 transported from the film forming section 800. As a result, the molten film 150 is heated, the solvent remaining on the molten film 150 is removed, the molten film 150 dries, and as a result, a resin film 1 is formed. This resin film 1 is transported downstream of the film drying section 600 by the operation (rotation) of the transport rollers 41 and wound onto the winding roller 46 located downstream.

[0068] The resin film 1 is manufactured by the method for manufacturing the resin film 1 using the resin film manufacturing apparatus 500 as described above.

[0069] A method for manufacturing the resin film 1 (the resin film of the present invention) includes an extrusion step of extruding a molten or softened resin composition as a molten film 150 in the shape of a strip; a molding step of flattening the first surface 15 and the second surface 13 of the molten film 150 and setting its thickness to a predetermined thickness to form the molten film 150; a stretching step of stretching the molten film 150 formed from the molten or softened resin composition in the extrusion direction; and a drying step of drying the molten film 150 stretched in the extrusion direction by heating.

[0070] The following details each step in the manufacturing process of resin film 1. [A] First, the molten or softened resin composition is extruded as a molten film 150 in the form of a strip (extrusion process).

[0071] In this extrusion process, a resin composition mainly composed of a polynorbornene-based resin for forming the resin film 1 is stored in the extruder 210 of the film supply unit 700. The resin composition stored in the extruder 210, in a molten or softened state, is then supplied to the kneader 230, where it is kneaded in its molten or softened state. Subsequently, the molten or softened resin composition is extruded as a molten film 150 through the kneader 230 and piping 212 to the film molding unit 800 through the opening 241 of the T-die 240. As a result, the molten or softened resin composition is continuously fed to the film molding unit 800 as a strip-shaped film, the molten film 150. Therefore, the extrusion direction in which the molten film 150 (resin composition) is extruded becomes the MD (flow direction) in which the molten film 150 flows (is transported).

[0072] In the method for producing the resin film 1, the resin composition used includes, in addition to the polynorbornene-based resin which is the main material of the resin film 1 to be formed, a solvent that has the ability to dissolve the polynorbornene-based resin.

[0073] Therefore, in order to melt or soften the resin composition, it is possible to set the heating temperature used to heat the resin composition to a temperature lower than the softening temperature of the polynorbornene-based resin. In this way, the heating temperature used to melt or soften the resin composition can be set to a lower temperature compared to when the resin composition does not contain a solvent. As a result, the production of the resin film 1, which is mainly composed of polynorbornene-based resin, can be carried out at a lower cost.

[0074] Furthermore, if the resin composition does not contain a solvent, when the resin composition is brought to a melted or softened state, the polynorbornene-based resin, which has a glass transition temperature of 200°C or higher, is heated to a high temperature, which can cause the polynorbornene-based resin to degrade in molecular weight, resulting in yellowing and a decrease in molecular weight of the resin composition. In the next step [B], when the molten film 150 is formed, the molten film 150 shrinks, which can cause curling of the molten film 150. In contrast, by including a solvent in the resin composition, the heating temperature for heating the resin composition can be set to a temperature lower than the softening temperature of the polynorbornene-based resin. Therefore, the occurrence of yellowing in the resin composition and the decrease in molecular weight and curling in the molten film 150 can be effectively suppressed or prevented. Thus, a resin film 1 with excellent transparency and excellent flatness can be manufactured.

[0075] Examples of solvents included in the resin composition include hydrocarbons such as water, decane, mesitylene, toluene, and xylenes; alcohols / ethers such as anisole, propylene glycol monomethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether, and diglyme; esters / lactones such as ethylene carbonate, ethyl acetate, N-butyl acetate, ethyl lactate, ethyl 3-ethoxypropionate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene carbonate, and γ-butyrolactone; ketones such as cyclopentanone, cyclohexanone, methyl isobutyl ketone, and 2-heptanone; and amides / lactams such as N-methyl-2-pyrrolidone. A single solvent containing one of these, or a mixed solvent containing two or more of these, is used as a solvent that exhibits solubility to dissolve polynorbornene-based resins.

[0076] In order to ensure that the heating temperature for heating the resin composition is set to a temperature lower than the softening temperature of the polynorbornene-based resin, a so-called good solvent with high solubility for dissolving the polynorbornene-based resin is preferably selected. Specifically, a Hansen solubility parameter (HSP) distance (Ra) for the polynorbornene-based resin of 7.00 (J / cm²) is preferred. 3 ) 0.5 Preferably, it is 3.00 (J / cm²). 3 ) 0.5 The following is more preferable: 2.00 (J / cm²) 3 ) 0.5 The following are more preferably selected. Such a solvent can be said to be a good solvent that can dissolve polynorbornene-based resins with high solubility. Therefore, the heating temperature used to heat the resin composition in order to bring it to a molten or softened state can be set to a temperature that is reliably lower than the softening temperature of the polynorbornene-based resin.

[0077] In this specification, the Hansen solubility parameter is a representation of the solubility parameter introduced by Hildebrand, divided into three components: the dispersion term δD, the polarity term δP, and the hydrogen bonding term δH, and expressed in three-dimensional space.

[0078] The dispersion term δD represents the effect due to dispersion forces, the polarity term δP represents the effect due to inter-dipole forces, and the hydrogen bonding term δH represents the effect due to hydrogen bonding forces. δD: Energy derived from intermolecular dispersion forces δP: Energy derived from intermolecular polar forces δH: Energy derived from intermolecular hydrogen bonding forces. It can be expressed as (Note that the respective units are (J / cm) 3 ) 0.5 (That is the case.)

[0079] The following relationship can be observed between Hildebrand's SP value and Hansen's HSP value. Hildebrand SP 2 =δD 2 +δP 2 +δH 2

[0080] Furthermore, the definition and calculation of HSP are described in Charles M. Hansen's "Hansen Solubility Parameters: A Users Handbook" (CRC Press, 2007).

[0081] Here, the dispersion term reflects van der Waals forces, the polar term reflects dipole moments, and the hydrogen bonding term reflects the effects of water, alcohol, etc. Furthermore, substances with similar vectors due to HSP can be judged to have high solubility.

[0082] The HSP distance (Ra) can be calculated, for example, by the following formula, where the HSP of the solute (polynorbornene-based resin) is (δD1, δP1, δH1) and the HSP of the solvent is (δD2, δP2, δH2).

[0083] HSP distance (Ra)= {4×(δD1-δD2) 2 +(δP1-δP2) 2 +(δH1-δH2) 2} 0.5

[0084] Furthermore, the Hansen HSP of the solvent can be calculated using the following formula, with volume as the mixing ratio.

[0085] [δDm, δPm, δHm] = [(a×(δD1+b×δD2),(a×(δP1+b×δP2),(a×(δH1+b×δH2)] / (a+b)

[0086] Examples of good solvents, i.e., solvents with high solubility for dissolving polynorbornene-based resins, include at least one of decane (boiling point 174.1°C), mesitylene (boiling point 164.1°C), and toluene (boiling point 110.7°C). In other words, a combination of polynorbornene-based resin and solvent included in the resin composition is a combination of polynorbornene-based resin and at least one of decane, mesitylene, and toluene.

[0087] Furthermore, the solvent content in the resin composition is preferably set to 5.0% by weight or more and 50.0% by weight or less, more preferably to 15.0% by weight or more and 30.0% by weight or less. By setting the solvent content in the resin composition within this range, the heating temperature used to heat the resin composition to bring it into a molten or softened state can be reliably set to a temperature lower than the softening temperature of the polynorbornene-based resin. Also, by setting the solvent content in the resin composition within this range, the drying of the molten film 150 by heating the molten film 150 in the next step [B] and the subsequent step [D] can be carried out quickly. Moreover, even if the solvent content in the resin composition is within this range, the storage modulus G' at 100°C of the resin composition exhibiting a molten or softened state can be reliably set to a size within the following range.

[0088] As mentioned above, the presence of a solvent in the resin composition allows the heating temperature for the resin composition to be set to a temperature reliably lower than the softening temperature of the polynorbornene-based resin. However, the heating temperature for the resin composition varies depending on the type of polynorbornene-based resin selected, but is generally preferably set within a temperature range of 70°C to 150°C, and more preferably 80°C to 120°C. By setting the heating temperature for the resin composition within this range to bring it to a molten or softened state, a low-cost resin film 1 can be obtained. Furthermore, since the polynorbornene-based resin can be reduced in molecular weight and yellowing of the resin composition can be effectively suppressed or prevented when bringing the resin composition to a molten or softened state, a resin film 1 with excellent transparency can be obtained.

[0089] Furthermore, even if the heating temperature for the resin composition is set to a temperature lower than the softening temperature of the polynorbornene-based resin by adding a solvent, the resin composition will exhibit a molten or softened state. Specifically, the resin composition exhibiting a molten or softened state will have a storage modulus G' of 1 × 10 at 100°C. 4 Pa or more 1×107 It is preferable that it be set within the range of Pa or less, 1 × 10 4 Pa or more 1×10 6 It is more preferable that the storage modulus G' is set within the range of Pa or less. By setting the storage modulus G' within the above range, the molten or softened resin composition can be reliably fed from the opening 241 of the T-die 240 to the film molding section 800 as a strip-shaped molten film 150.

[0090] Furthermore, the resin composition containing the polynorbornene resin and solvent becomes molten or softened when kneaded while heated. When the resin composition is kneaded in the kneader 230, the shear stress applied to the resin composition is preferably set to 3 kPa or more and 1800 kPa or less, more preferably to 6 kPa or more and 1400 kPa or less. This ensures that the resin composition is reliably molten or softened, and can be reliably fed from the opening 241 of the T-die 240 as a strip-shaped molten film 150 to the film molding section 800.

[0091] Furthermore, in addition to the polynorbornene-based resin and solvent, the resin composition includes the aforementioned additives if the resin film 1 contains additives other than the polynorbornene-based resin.

[0092] [B] Next, the first surface 15 and the second surface 13 of the molten film 150, which is a film in which the resin composition exhibiting a molten or softened state is formed into a strip, are flattened, and the average thickness is set to a predetermined thickness, thereby molding the molten film 150 (resin composition) (molding process).

[0093] This molding process is carried out by supplying molten film 150 between touch roll 110 and touch roll 120, and then supplying molten film 150 again between touch roll 120 and touch roll 130.

[0094] In this process, the outer surfaces of the touch roll 110, the touch roll 120, and the touch roll 130 are each smooth and roll-shaped. Therefore, the first surface 15 and the second surface 13 of the molten film 150 are flattened by being pressed against the smooth outer surfaces of each roll.

[0095] Furthermore, the distance between the outer surface of the touch roll 110 and the outer surface of the touch roll 120, and the distance between the outer surface of the touch roll 120 and the outer surface of the touch roll 130 are set to the thickness of the resin film 1 to be formed, and by appropriately setting these distances to a predetermined size, a molten film 150 of the desired thickness, and thus the resin film 1, can be obtained.

[0096] Thus, in this process [B], the touch roll 110, touch roll 120, and touch roll 130 are used to flatten the first surface 15 and the second surface 13, and to set the thickness of the molten film 150, respectively.

[0097] In the flattening of the first surface 15 and the second surface 13 of the molten film 150 using such touch rolls 110, 120, and 130, the resin composition used in the manufacturing method of the resin film 1 contains a polynorbornene-based resin and a solvent as the resin composition exhibiting a molten or softened state. As a result, as explained in the previous step [A], this resin composition effectively suppresses or prevents curling in the molten film 150, which is formed into a strip-shaped film, and allows the molten film 150 to be supplied from the film supply unit 700 to the film molding unit 800 (touch rolls 110, 120, and 130). Therefore, the flattening of the first surface 15 and the second surface 13 of the molten film 150, as well as the setting of the thickness of the molten film 150, can be performed with excellent precision using the touch rolls 110, 120, and 130.

[0098] Furthermore, curling in the molten film 150 occurs frequently, especially when using a polynorbornene-based resin with a glass transition temperature of 200°C or higher, as in the present invention, and when forming a thick molten film 150, if the resin composition does not contain a solvent. In such cases, using a resin composition containing both a polynorbornene-based resin and a solvent can more effectively suppress or prevent the occurrence of curling. Therefore, even a thick resin film 1 with an average thickness of 20 μm to 500 μm can be formed with excellent precision in the subsequent process [C].

[0099] In this method for manufacturing the resin film 1, it is preferable to heat the molten film 150 (resin composition) during the molding of the molten film 150 (resin composition) in step [B]. This makes it possible to remove a portion of the solvent contained in the molten film 150 from the molten film 150.

[0100] The heating of the molten film 150 (resin composition) is carried out by heating the roll equipped with a heating means, which is at least one of the touch rolls 110 to 130.

[0101] In step [B], the heating temperature for heating the molten film 150 (resin composition) is preferably set to approximately 80°C to 160°C, more preferably to approximately 100°C to 140°C. This ensures that a portion of the solvent contained in the molten film 150 is reliably removed from the molten film 150.

[0102] Furthermore, by removing this solvent, the solvent content in the molten film 150, i.e., the amount of solvent remaining in the resin composition, is preferably set to approximately 5.0% by weight or more and 15.0% by weight or less, and more preferably to approximately 7.0% by weight or more and 13.0% by weight or less. This ensures that, in the next step [C], when the molten film 150 (resin composition) is stretched along the MD (flow direction), the polynorbornene-based resin contained in the molten film 150 is reliably oriented along the TD (direction perpendicular to the flow).

[0103] Furthermore, when the toluene content of the molten film 150 as a solvent is 10% by weight, it is preferable that the storage modulus G' at 30°C and 60°C is set to within the range of 0.50 GPa to 2.50 GPa, and more preferably within the range of 1.00 GPa to 1.70 GPa, respectively. By setting the storage modulus G' at 30°C and 60°C to within the aforementioned ranges, when the molten film 150 is stretched along the MD on which it is transported in the next step [C], the polynorbornene-based resin contained in the molten film 150 can be reliably oriented along the TD perpendicular to the MD of the molten film 150.

[0104] [C] Next, the molten or softened resin composition, with the first surface 15 and the second surface 13 flattened and set to a predetermined thickness, is stretched along the extrusion direction from which the molten film 150 (resin composition) was extruded, i.e., the MD (flow direction) in which the molten film 150 (resin composition) was conveyed (stretching step).

[0105] By stretching the molten film 150 along the extrusion direction, the polynorbornene-based resin contained in the molten film 150 (resin composition) can be oriented along the TD (direction perpendicular to the flow) which is perpendicular to the extrusion direction of the molten film 150 (resin composition), i.e., the MD (flow direction) of the molten film 150. Therefore, the resin film 1 obtained in the next step [D] can be made to have a low coefficient of thermal expansion.

[0106] This stretching process is carried out when the molten film 150 (resin composition) is transported between the touch roll 130 and the winding roller 46, and is performed in the film drying section 600 located between the touch roll 130 and the winding roller 46 until the solvent contained in the molten film 150 is removed by heating and the resin film 1 is formed.

[0107] In this stretching process, the stretching of the molten film 150 (resin composition) along the MD (flow direction) is carried out based on the fact that the conveying speed of the molten film 150 by the conveyor roller 41 is set faster than the winding speed of the resin film 1 by the winding roller 46, and the conveying speed of the molten film 150 by the touch rolls 110-130. This difference in speed causes tension to act on the molten film 150 (resin composition) in the MD (flow direction).

[0108] Furthermore, in step [C], the stretching ratio for stretching the molten film 150 (resin composition) is preferably set to approximately 1.2 times or more and 9.0 times or less, more preferably to approximately 1.5 times or more and 7.0 times or less. This ensures that when the molten film 150 (resin composition) is stretched along the MD (flow direction) of the molten film 150, the polynorbornene-based resin contained in the molten film 150 (resin composition) is reliably oriented along the TD (direction perpendicular to the flow) which is perpendicular to the stretching direction.

[0109] Furthermore, in step [C], the temperature of the molten film 150 (resin composition) when stretching the molten film 150 (resin composition), that is, the temperature of the atmosphere when transporting it between the touch roll 130 and the film drying section 600, is preferably set to about 40°C to 80°C, more preferably to about 50°C to 70°C. This ensures that when the molten film 150 (resin composition) is stretched along the MD (flow direction) of the molten film 150, the polynorbornene-based resin contained in the molten film 150 (resin composition) is reliably oriented along the TD (direction perpendicular to the flow) which is perpendicular to the stretching direction.

[0110] [D] Next, the molten film 150 (resin composition), which is stretched along the MD (flow direction) in which the molten or softened resin composition is transported, is dried by heating (drying step).

[0111] This makes it possible to obtain a resin film 1, which is a film formed from a resin composition in the shape of a strip, in a state where it is stretched along the MD (flow direction) in which the resin film 1 is transported.

[0112] This drying process is carried out by transporting the molten film 150, which has been stretched along the MD (flow direction), to the film drying section 600. Upon transport of the molten film 150 to the film drying section 600, hot air is blown from each hot air supply section 61 onto the molten film 150, whose first surface 15 and second surface 13 have been flattened. As a result, the solvent contained in the resin composition volatilizes, and the molten film 150 is heated and dried, forming a resin film 1 with its first surface 15 and second surface 13 flattened.

[0113] At this time, in step [C], the stretching of the molten film 150 along the extrusion direction causes the polynorbornene-based resin contained in the molten film 150 (resin composition) to be oriented along the TD (direction perpendicular to the flow) of the molten film 150. In step [D], this state is maintained as the molten film 150 is heated and dried to form the resin film 1. Therefore, the formed resin film 1 can be made to have a low coefficient of thermal expansion, that is, satisfying the requirement that the linear thermal expansion coefficient below the glass transition temperature is 40 ppm / K or less.

[0114] Furthermore, in step [D], the heating temperature for heating the molten film 150 (resin composition) is preferably set to approximately 100°C to 180°C, more preferably to approximately 120°C to 160°C. This ensures that any solvent remaining in the molten film 150 is reliably removed from the molten film 150, thereby obtaining the resin film 1.

[0115] Through the above process, a resin film 1 is produced, which is mainly composed of a polynorbornene-based resin having a glass transition temperature of 200°C or higher, and in which this polynorbornene-based resin is oriented along the TD (direction perpendicular to the flow). In other words, a resin film 1 is produced that satisfies the requirement that the linear thermal expansion coefficient of the polynorbornene-based resin below the glass transition temperature is 40 ppm / K or less.

[0116] The resin film of the present invention has been described above, but the present invention is not limited thereto.

[0117] For example, in the resin film of the present invention, each component can be replaced with any component that can perform a similar function, or any component can be added. Furthermore, although the above embodiment described the resin film of the present invention as a single layer body mainly composed of a polynorbornene-based resin in the form of a film, it is not limited to this, and may be composed of a laminate in which other layers are laminated onto this single layer body.

[0118] Furthermore, in the method for manufacturing the resin film of the present invention, one or more steps can be added for any purpose.

[0119] Furthermore, although the above embodiment described a case in which the molten film 150 (resin composition) is stretched along the conveying MD, the invention is not limited to this case. The molten film 150 (resin composition) may also be stretched along the TD (direction perpendicular to the flow), or stretched along both the MD and the TD. When the molten film 150 is stretched along the TD, this can be done by arranging a tensioning device between the touch roll 130 and the winding roller 46 that can stretch the conveyed molten film 150 along the TD. In other words, the resin film 1 may be stretched along the MD, stretched along the TD, or stretched along both the MD and the TD. [Examples]

[0120] The present invention will be described in more detail below based on the examples. However, the present invention is not limited in any way by these examples.

[0121] 1. Preparation of raw materials First, the raw materials used in the production of resin film 1 for each example and comparative example are shown below.

[0122] (PNB resin 1) PNB-based resin 1 is norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 80:20, glass transition temperature: 295°C, weight-average molecular weight (Mw): 2.0 × 10⁻⁶). 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0123] (PNB resin 2) As PNB-based resin 2, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 95:5, glass transition temperature: 310°C, weight-average molecular weight (Mw): 1.5 × 10⁻⁶) 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0124] (PNB resin 3) As PNB-based resin 3, norbornene (NB)-ethylidene norbornene (EthylideneNB) copolymer (manufactured by Promerus, NB:EthylideneNB = 80:20, glass transition temperature: 310°C, weight-average molecular weight (Mw): 1.9 × 10⁻⁶) 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0125] (PNB resin 4) As PNB-based resin 4, norbornene (NB)-ethylidene norbornene (EthylideneNB) copolymer (manufactured by Promerus, NB:EthylideneNB = 95:5, glass transition temperature: 312°C, weight-average molecular weight (Mw): 1.9 × 10⁻⁶) 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0126] (PNB resin 5) As PNB-based resin 5, norbornene (NB)-cyclohexanenorbornene (CyclohexaneNB) copolymer (manufactured by Promerus, NB:CyclohexaneNB = 80:20, glass transition temperature: 300°C, weight-average molecular weight (Mw): 1.5 × 10⁻⁶) 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0127] (PNB resin 6) As PNB-based resin 6, norbornene (NB)-cyclohexanenorbornene (CyclohexaneNB) copolymer (manufactured by Promerus, NB:CyclohexaneNB = 95:5, glass transition temperature: 305°C, weight-average molecular weight (Mw): 1.8 × 10⁻⁶) 5 A sample was prepared with a concentration of g / mol, a yellowing onset temperature of 190°C, and a molecular weight decrease onset temperature of 240°C.

[0128] (PNB resin 7) As the PNB-based resin 7, polycycloolefin norbornene (COP) (manufactured by Zeon Corporation, glass transition temperature: 155°C, yellowing onset temperature: 350°C) was prepared.

[0129] (Solvent 1) Toluene (manufactured by Kanto Chemical Co., Ltd., "40180-01", boiling point: 110.7°C) was prepared as solvent 1.

[0130] 1. Formation of resin film [Example 1] [1] First, a resin composition was prepared by stirring and mixing PNB resin 1 (NB:HexylNB=80:20) and solvent 1 (toluene) so that their respective contents were 50% by weight and 50% by weight.

[0131] Furthermore, the Hansen solubility parameter (HSP) distance (Ra) of solvent 1 (toluene) to PNB resin 1 (NB:HexylNB=80:20) was calculated using the calculation software HSPiP 5th edition (available from http: / / pirika.com / JP / HSP / index-j.html) and was found to be 2.60 (J / cm²). 3 ) 0.5 That was the case.

[0132] [2] Next, the prepared resin composition was placed in the extruder 210 of the resin film manufacturing apparatus 500 shown in Figure 2, and then supplied from the extruder 210 to the kneader 230. The kneader 230, a twin-screw kneader, was set to rotate at 70 rpm, a heating temperature of 100°C, and a kneading time of 1 minute, and the PNB-based resin 1 (NB:HexylNB=80:20) and solvent 1 (toluene) were kneaded in the resin composition. After this kneaded resin composition was supplied to the T-die 240, and then extruded from the opening 241 of the T-die 240 as a softened molten film 150 to the film molding section 800.

[0133] [3] Next, the molten film 150, which is in the form of a film extruded from the opening 241, is sandwiched between the touch roll 110 and the touch roll 120, and between the touch roll 120 and the touch roll 130 to flatten the first surface 15 and the second surface 13 of the molten film 150, and the solvent is removed from the molten film 150 by heating of the molten film 150 by the touch rolls 110 to 130 until the solvent remaining in the molten film 150 is 10% by weight. The storage modulus G' of the molten film 150 at 30°C and 60°C was measured using a dynamic viscoelasticity analyzer (DMA, TA Instruments, "Q800") under the conditions of a heating rate of 5°C / min, a temperature range of 30°C to 320°C, and an angular frequency of 1 Hz, and was found to be 1.47 GPa and 1.43 GPa, respectively.

[0134] [4] Next, the molten film 150 was stretched along the MD by setting the transport speed of the molten film 150 by the transport roller 41 and the winding speed of the resin film 1 by the winding roller 46 to be faster than the transport speed of the molten film 150 by the touch rolls 110-130 until the molten film 150 was supplied to the film drying section 600. The ambient temperature until the molten film 150 was supplied to the film drying section 600 was set to 60°C. The stretching ratio of the molten film 150 at this time was 1.39 times.

[0135] [5] Next, the molten film 150 stretched along the MD was supplied to the film drying section 600, and hot air at 150°C was blown onto the molten film 150 from the hot air supply section 61 of the film drying section 600 for 60 minutes to heat and dry the molten film 150 and obtain the resin film 1 of Example 1 with an average thickness of 88 μm.

[0136] [Examples 2-6] Except for changing the type of PNB resin used as the thermoplastic resin in the resin composition in the above step [1] as shown in Table 1, resin films 1 of Examples 2 to 6 were obtained in the same manner as in Example 1.

[0137] [Comparative Examples 1-6] In step [4], the resin films 1 of Comparative Examples 1 to 6 were obtained in the same manner as in Examples 1 to 6 and Comparative Example A1, except that the stretching of the molten film 150 along the MD was omitted by setting the transport speed of the molten film 150 by the transport roller 41 and the winding speed of the resin film 1 by the winding roller 46 to the same speed as the transport speed of the molten film 150 by the touch rolls 110 to 130.

[0138] [Comparative Example A1] In step [1], the type of thermoplastic resin contained in the resin composition was changed to a PNB-based resin 7, and in step [4], the transport speed of the molten film 150 by the transport roller 41 and the winding speed of the resin film 1 by the winding roller 46 were set to the same speed as the transport speed of the molten film 150 by the touch rolls 110 to 130, thereby omitting the stretching of the molten film 150 along the MD, in which case the resin film 1 of Comparative Example A1 was obtained in the same manner as in Example 1.

[0139] 2. Evaluation The resin film 1 of each example and each comparative example was evaluated by the following method.

[0140] <Measuring linear thermal expansion coefficient> For each example and comparative example, a random pattern was created on the resin film 1 by spraying ink onto the film surface and then drying it on a hot plate at 100°C for 5 minutes, in order to apply the digital image correlation method. From this film, pieces measuring 10 mm in width and 10 mm in length were cut out to serve as test specimens.

[0141] Next, the specimen was placed on a large sample cooling and heating stage for microscopes (Linkam Corporation, "T95-HS"), and the surface image of the specimen was captured using a scanning confocal laser microscope (Olympus Corporation, "LEXT OLS4000") immediately after heating at a rate of 10°C / min within the range of 50-150°C, holding for 1 minute for every 5°C increase. By analyzing the digital images obtained by proceeding with heating, temperature holding, and imaging in stages, the normal strain in the stretching direction of the specimen during the heating process of 50-150°C could be extracted, and the linear thermal expansion coefficient could be calculated from the slope of the straight line obtained by linearly approximating the normal strain as a function of temperature. This was calculated as the linear thermal expansion coefficient (ppm / K) below the glass transition temperature (Tg) for each example and each comparative example of resin film 1.

[0142] <Orientation degree measurement test> For each example and comparative example of resin film 1, X-ray diffraction images were obtained from the cross-sectional direction of resin film 1 at a synchrotron radiation facility beamline (e.g., SPring-8 BL03XU beamline second hutch). The measurement conditions were a wavelength of 0.1 nm and a camera length of 40 cm. A Pilatus 1M two-dimensional detector was used. From the obtained X-ray diffraction images, a one-dimensional graph was obtained in the circumferential direction representing the X-ray diffraction intensity derived from the interchain distance of the polynorbornene-based resin in resin film 1. Subsequently, the degree of orientation of the polynorbornene-based resin in resin film 1 was calculated by substituting the half-width H of the diffraction intensity peaks in the one-dimensional graph into the following equation 1. Orientation degree=(180-H) / 180… (Formula 1)

[0143] <Dielectric Constant Measurement Test> For each example and comparative example of resin film 1, a specimen measuring 3.5 mm in width and 80 mm in length was cut out and used as a test piece. Then, the relative permittivity (Dk(-)) and dielectric loss tangent (Df(-)) of resin film 1 were measured using a dielectric constant measuring device (AET Corporation, "ADMS010c") that conforms to JIS C 2526 and uses a cavity resonator method.

[0144] <Yellowing test> For each example and comparative example, a sample (50 mm wide, 50 mm long, 200 μm to 500 μm thick) of the resin composition for obtaining the resin film was heated in a hot air circulating oven set to 180°C under an oxygen atmosphere for 60 minutes to obtain a molded body.

[0145] Next, the degree of yellowing (ΔYI) of the molded articles obtained from the resin films of each example and each comparative example was measured using a Konica Minolta CR-200 color difference meter and evaluated as follows.

[0146] ◎: ΔYI is 8.0 or less, so there is no change in appearance. ○: When ΔYI is between 8.0 and 20.0, slight changes in appearance can be observed. ×: When ΔYI exceeds 20.0, a clear change in appearance is observed.

[0147] <Molecular weight reduction test> The weight-average molecular weight (Mw) of the thermoplastic resin contained in resin film 1 of each example and comparative example was obtained by creating a calibration curve for a polystyrene standard substance using gel permeation chromatography (GPC) and calculating the molecular weight using this calibration curve.

[0148] Then, based on the weight-average molecular weight (Mw) of the raw materials of the thermoplastic resin contained in the resin films of each example and comparative example, the Mw reduction rate of the thermoplastic resin contained in the resin films of each example and comparative example was measured and evaluated as follows.

[0149] ◎: A decrease in Mw of less than 5.0% does not necessarily mean that a decrease in molecular weight has been confirmed. ○: A slight decrease in molecular weight is observed when the Mw decrease rate is less than 10.0%. ×: A decrease in Mw (molecular weight) of over 20.0% clearly indicates a decrease in molecular weight.

[0150] <Curl test> For each example and comparative example, the presence or absence of curling in the resin film 1 was visually observed.

[0151] Then, based on the observed curl state, the resin film 1 of each example and comparative example was evaluated as follows.

[0152] ◎: No curling was observed. ○: Although some curling is observed, It is of a quality suitable for use as a resin film 1. ×: Clear curling is observed.

[0153] The evaluation results for the resin films obtained in each example and comparative example are shown in Tables 1 and 2 below, respectively.

[0154] [Table 1]

[0155] [Table 2]

[0156] As shown in Tables 1 and 2, in each example, the resin film containing a polynorbornene-based resin exhibiting a glass transition temperature of 200°C or higher satisfies the requirement that the linear thermal expansion coefficient of the resin film below the glass transition temperature be 40 ppm / K or less, due to the orientation of the polynorbornene-based resin along the TD (direction perpendicular to the flow), demonstrating that a low thermal expansion coefficient was achieved.

[0157] In contrast, in the resin films containing polynorbornene-based resins in each comparative example, the polynorbornene-based resin was not oriented, and as a result, the linear thermal expansion coefficient below the glass transition temperature of the resin film could not be satisfied with 40 ppm / K or less, indicating that a low thermal expansion coefficient was not achieved. [Explanation of symbols]

[0158] 1. Resin film 13 Side 2 15 Page 1 41 Conveyor rollers 46 Winding roller 61 Hot air supply section 110 Touch Roll 120 Touch Roll 130 Touch Roll 150 Melting Film 210 Extruder 212 Piping 230 Mixing machine 240 T-die 241 Opening 400 Film transport section 500 Resin film manufacturing equipment 600 Film drying section 700 Film supply unit 800 Film molding section

Claims

1. A resin film composed primarily of polynorbornene-based resin, The aforementioned polynorbornene-based resin has a glass transition temperature of 200°C or higher. The resin film has a linear thermal expansion coefficient of 40 ppm / K or less below the glass transition temperature. The resin film is stretched in at least one of the MD and TD directions. The polynorbornene-based resin is oriented along the aforementioned one direction, The resin film is characterized in that the polynorbornene-based resin is a copolymer represented by the following general formula (5Y). 【Chemistry 1】 [In the general formula (5Y) above, n and m are each independently an integer of 1 or more, and group X is one of the following: a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, or a glycidyl ether group.]

2. The resin film according to claim 1, wherein the relative permittivity at a frequency of 10 GHz is 1.5 or more and 3.5 or less.

3. The resin film has a dielectric loss tangent of 1.0 × 10 at a frequency of 10 GHz. －４ The above 2.0 x 10 －３ The resin film according to claim 1, which is as follows:

4. The resin film according to claim 1, wherein the average thickness of the resin film is 20 μm or more and 500 μm or less.

Images