resin film

Abstract

To provide a resin film that is primarily composed of polynorbornene-based resin and exhibits a white color. [Solution] The resin film 1 of the present invention contains a polynorbornene-based resin as its main material and satisfies the requirement that its whiteness be between 70 and 130 according to ASTM E313. Furthermore, when the average thickness of the resin film 1 is 0.2 mm, it is preferable that the total light transmittance of visible light with wavelengths between 400 nm and 780 nm is 10.0% or less.

Description

[Technical Field]

[0001] The present invention relates to a resin film. [Background Art]

[0002] In recent years, resin films having a white color tone (white films) have been widely used in various fields, such as back light-reflecting films for surface light source devices of organic EL displays and liquid crystal displays, back light-reflecting films for illuminated signs, back light-reflecting films for solar cells, and labels with a printed surface applied to bottles used for containing beverages, seasonings and the like (see, for example, Patent Document 1).

[0003] Depending on the field of application, that is, depending on the intended use of such a resin film composed of a porous material, there is sometimes a demand for a resin film that achieves high heat resistance and low dielectric properties such as low specific dielectric constant (Dk) and low dielectric loss tangent (Df).

[0004] Under such circumstances, resin films mainly composed of polynorbornene-based resins are generally known to have excellent heat resistance and low dielectric constant (see, for example, Patent Document 2).

[0005] For this reason, in reality, there has been a demand for providing a white-colored resin film that is mainly composed of a polynorbornene-based resin. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Unexamined Patent Publication No. 2005-011923 [Patent Document 2] Japanese Unexamined Patent Publication No. 2001-226494 [Brief Summary of the Invention] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a resin film that is composed mainly of a polynorbornene-based resin and exhibits a white color. [Means for solving the problem]

[0008] These objectives are achieved by the present invention as described in (1) to (11) below. (1) A resin film mainly composed of polynorbornene resin, A resin film characterized by having a whiteness of 70 to 130 according to the ASTM E313 standard.

[0009] (2) The resin film described in (1) above, wherein the average thickness of the resin film is 0.2 mm, and the total light transmittance of visible light with wavelengths of 400 nm to 780 nm is 10.0% or less.

[0010] (3) The resin film described in (2) above, wherein the average thickness of the resin film is 0.2 mm, and the total reflectance of visible light with wavelengths of 400 nm to 780 nm is 50.0% or more.

[0011] (4) The resin film is the resin film described in (1) above, which does not contain a white coloring agent.

[0012] (5) The resin film is the resin film described in (1) above, which is composed of a porous material.

[0013] (6) The resin film, in a cross-section formed by cutting it in the thickness direction, contains pores with a diameter of 5 μm or less, and in the scattering image obtained by small-angle X-ray scattering measurement (SAXS), when the magnitude of the scattering vector is q, the magnitude of the scattering vector q is 0.05 nm. -1 More than 0.5nm -1 Within the following range, the small-angle X-ray scattering intensity I(q) is q -4A resin film as described in (5) above, proportional to the above.

[0014] (7) The resin film is the resin film described in (1) above, wherein the relative permittivity at a frequency of 10 GHz is less than 2.0.

[0015] (8) The resin film has a dielectric loss tangent of 5.0 × 10 at a frequency of 10 GHz. -4 The resin film described in (1) above, which is less than [a certain value].

[0016] (9) The resin film is the resin film described in (1) above, wherein its average thickness is 20 μm or more and 500 μm or less.

[0017] (10) The resin film according to (1) above, wherein the polynorbornene-based resin has a glass transition temperature of 200°C or higher.

[0018] (11) The resin film described in (10) above, wherein the polynorbornene-based resin is represented by the following general formula (1). [ka] [In the general formula (1) 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.] [Effects of the Invention]

[0019] According to the present invention, a resin film containing polynorbornene-based resin as the main material satisfies the requirement that the whiteness of ASTM E313 be between 70 and 130. Therefore, this resin film can be said to be composed of polynorbornene-based resin as the main material, exhibiting a white color and being visible as white. [Brief explanation of the drawing]

[0020] [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. [Figure 3] This is an electron microscope image of a cross-section of the resin film of Example 1. [Figure 4] This graph shows the relationship between the magnitude q of the scattering vector and the small-angle X-ray scattering intensity I(q) in the scattering image of the resin film of Example 1. [Modes for carrying out the invention]

[0021] The resin film of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings. <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".

[0022] As shown in Figure 1, the resin film 1 (the resin film of the present invention) is in the form of a film (sheet), contains polynorbornene-based resin as its main material, and satisfies the requirement that its whiteness is 70 or more and 130 or less according to the ASTM E313.

[0023] The resin film 1, which is mainly composed of polynorbornene resin, is generally known to exhibit excellent heat resistance and to have a low dielectric constant. However, in this invention, the requirement of a whiteness of 70 to 130 according to ASTM E313 is satisfied by manufacturing the resin film 1 as a porous material using the resin film 1 manufacturing method described later. Thus, the resin film 1 exhibits a white color and can be visually perceived as white.

[0024] The following describes this resin film 1. The resin film 1 is composed primarily of a polynorbornene-based resin.

[0025] The polynorbornene-based resin is a type of so-called high Tg resin that exhibits a high Tg (high glass transition temperature), and is not particularly limited. Examples thereof include those containing a structural unit represented by the following general formula (1Y). This makes it possible to reliably obtain the resin film 1 having excellent heat resistance and a low dielectric constant.

[0026] [Chemical formula]

[0027] In general formula (1Y), R 1 to R 4 each are any one of hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, a glycidyl ether group, and the following substituent (2Y). Further, m is an integer of 0 to 4.

[0028] [Chemical formula]

[0029] In general formula (2Y), R 5 each is hydrogen, a methyl group or an ethyl group, and R 6 , R 7 and R 8 are each any one of 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. Further, n is an integer of 0 to 5.

[0030] The linear or branched alkyl group having 1 to 20 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.

[0031] The aforementioned aromatic group is not particularly limited, but examples include a phenyl group, a phenethyl group, a naphthyl group, and the like.

[0032] The aforementioned alicyclic group is not particularly limited, but examples include cyclohexyl group, norborneyl group, dihydrodicyclopentadiethyl group, tetracyclododecyl group, methyltetracyclododecyl group, tetracyclododecadiethyl group, dimethyltetracyclododecyl group, ethyltetracyclododecyl group, ethylidenyltetracyclododecyl group, phenyltetracyclododecyl group, trimers of cyclopentadiethyl group, and other alicyclic groups.

[0033] R in the substituent (2Y) 5 Examples of these are, but are not limited to, hydrogen, methyl groups, or ethyl groups.

[0034] R in the substituent (2Y) 6 , R 7 and R 8 Each of these can be, but is not limited to, 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.

[0035] Examples of such substituents include, specifically, methoxy, ethoxy, propoxy, butoxy, pentyloxy, acetoxy, propiooxy, butyloxy, methylperoxy, isopropylperoxy, t-butylperoxy, phenoxy, hydroxyphenoxy, and naphthyloxy groups.

[0036] Furthermore, in the general formula (1Y), m is an integer from 0 to 4 and is not particularly limited, but 0 or 1 is preferred. 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).

[0037] [ka]

[0038] [ka]

[0039] 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.

[0040] Furthermore, the polynorbornene resin is not particularly limited and may be a monopolymer formed from a single structural unit represented by the general formula (1Y), or a copolymer formed from multiple structural units. However, it is particularly preferable that it be a copolymer having a structural unit represented by the general formula (3Y), and more specifically, a copolymer represented by the general formula (5Y) below. This makes it possible to more reliably produce a polynorbornene resin that exhibits a particularly high Tg, such as a glass transition temperature of 200°C or higher.

[0041] [ka]

[0042] 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.

[0043] 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.

[0044] 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 resin film 1 manufacturing method described later, the resin film 1 can be made to satisfy the requirement of a whiteness of 70 or more and 130 or less according to ASTM E313. The weight-average molecular weight (Mw) can be obtained by creating a calibration curve for polystyrene standard substances using gel permeation chromatography (GPC) measurement and calculating the weight-average molecular weight (Mw) using this calibration curve.

[0045] The polynorbornene-based resin preferably has a glass transition temperature of 200°C or higher, more preferably 280°C or higher, and even more preferably 300°C to 340°C. This allows the resin film 1 to exhibit superior heat resistance, i.e., higher heat resistance. Furthermore, even when the resin film 1 contains 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 made to have excellent flatness and excellent whiteness.

[0046] Furthermore, by incorporating a polynorbornene-based resin as the main material, the dielectric constant of the resin film 1 is reduced. Specifically, the relative dielectric constant (Dk(-)) of the resin film 1 at a frequency of 10 GHz can be set to preferably less than 2.0, and more preferably within the range of 1.0 to 1.8. Also, the dielectric loss tangent (Df(-)) at a frequency of 10 GHz is preferably 5.0 × 10⁻⁶. -4 Less than 5.0 × 10 -5 The above 4.5 × 10 -4 Set it within the following range.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] <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.

[0052] Before describing the resin film manufacturing method, the following section will first describe the resin film manufacturing apparatus to which this method is applied.

[0053] (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".

[0054] The resin film manufacturing apparatus 500 shown in Figure 2 includes a film supply unit 700, a film adjustment unit 800, a film immersion unit 900, a film drying unit 600, and a film transport unit 400.

[0055] 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.

[0056] In the film supply unit 700 with this configuration, a resin composition containing a polynorbornene-based resin, which is the main resin material for forming the resin film 1, and a good solvent that exhibits solubility for this polynorbornene-based resin, 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 the resin composition in its molten or softened state. Subsequently, the molten or softened resin composition forms a film-like molten film 150, which is supplied to the film adjustment unit 800 via the kneader 230, piping 212, and the T-die 240 (with its opening 241).

[0057] In this embodiment, the film adjustment unit 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 oriented 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.

[0058] 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.

[0059] 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 into the film immersion unit 900. By continuously feeding the molten or softened molten film 150 from the film supply unit 700 into this film adjustment 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 (adjusted) to the desired size.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] In this embodiment, the film supply unit 700 and the film adjustment unit 800 constitute a film molding unit that forms a resin composition containing a polynorbornene-based resin and a good solvent into a film.

[0065] The film transport unit 400 sequentially transports (supplies) the molten film 150 sent from the film adjustment unit 800 to the film immersion unit 900 and the film drying unit 600, and also includes a transport roller 41 that discharges 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.

[0066] 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.

[0067] 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 adjustment 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.

[0068] 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.

[0069] The film immersion section 900 includes an immersion tank 92 and an immersion roll 91. This film immersion section 900 is located between two transport rollers 41 located upstream in the transport direction of the molten film 150, downstream of the film adjustment section 800 (touch roll 130), and is supported and fixed to the frame that supports the entire resin film manufacturing apparatus 500.

[0070] The immersion tank 92 is a storage tank for storing a poor solvent. Multiple immersion rolls 91 (five in Figure 2) are provided within the immersion tank 92, and each immersion roll 91 is positioned (height) so that it is immersed in the poor solvent when it is stored in the immersion tank 92. These rolls are made of a metal material such as stainless steel. The pivot axes (central axes) of these rolls are all facing the same direction, and in this embodiment, those positioned at a high position (upper side) and those positioned at a low position (lower side) are arranged alternately along the transport direction of the molten film 150 from upstream to downstream. Furthermore, each roll is rotatably supported relative to the immersion tank 92.

[0071] The molten film 150 is wrapped around these immersion rolls 91 in an up-and-down manner so as to be folded. As the immersion rolls 91 rotate, the molten film 150 supplied from the film adjustment unit 800 passes through the immersion tank 92 and is then continuously fed to the film drying unit 600. By continuously feeding the molten film 150, which has been set (adjusted) to a predetermined thickness, into this film immersion unit 900, the molten film 150 is immersed in the poor solvent in the immersion tank 92. As a result, the interaction between the good solvent contained in the molten film 150 and the poor solvent causes a change in the structure of the molten film 150, thus forming a porous structure in the molten film 150. In other words, a molten film 150 composed of a porous material is formed.

[0072] Furthermore, by appropriately changing the type of combination of good solvent and poor solvent, the immersion time in the poor solvent, the content of good solvent in the molten film 150, etc., the porosity of the porous body constituting the molten film 150 and, consequently, the resin film 1, as well as the particle size and shape of the pores (holes) in the porous body, can be appropriately set.

[0073] The film drying section 600 has a pair of hot air supply sections 61. These hot air supply sections 61 are located between two transport rollers 41 located downstream in the transport direction of the molten film 150, downstream of the film immersion section 900 in the transport direction of the molten film 150, and are positioned above and below the molten film 150, facing it. They are supported and fixed to the frame that supports the entire resin film manufacturing apparatus 500. Each hot air supply section 61 has a built-in heating section (heating fan) (not shown), and the hot air heated by this heating section is blown onto the molten film 150 transported from the film immersion section 900. As a result, the molten film 150 is heated, removing any remaining solvent (a mixed solvent of good and poor solvents) from the molten film 150, drying the molten film 150, and as a result, a porous resin film 1 is formed. That is, based on its porous composition, a resin film 1 is formed that exhibits a white color and is visible as white. This resin film 1 is transported downstream of the film drying section 600 by the operation (rotation) of the transport roller 41, and is wound onto the winding roller 46 located downstream.

[0074] By the resin film manufacturing method using the resin film manufacturing apparatus 500 described above, a resin film 1 is produced that appears white due to its white color.

[0075] In this embodiment, the 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 strip-shaped molten film 150; an adjustment step of flattening the first surface 15 and the second surface 13 of the molten film 150 and adjusting the thickness of the molten film 150 to a predetermined thickness to form the molten film 150 into a film; an immersion step of immersing the molten film 150, which has been formed from a molten or softened resin composition into a film, in a poor solvent to make the molten film 150 a porous body; and a drying step of heating the molten film 150 to dry it.

[0076] 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).

[0077] In this extrusion process, a resin composition mainly composed of 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 adjustment 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 adjustment unit 800 as a strip-shaped film 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 conveyed).

[0078] In this embodiment, the resin composition used includes not only a polynorbornene-based resin, which is the main material of the resin film 1 to be formed, but also a good solvent that has the ability to dissolve the polynorbornene-based resin.

[0079] 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 good solvent. As a result, the production of a resin film 1, which uses a polynorbornene-based resin as the main material and exhibits a white color, can be carried out at a lower cost.

[0080] Furthermore, if the resin composition does not contain a good solvent, when the resin composition is brought to a melted or softened state, the polynorbornene-based resin, which is a high-Tg resin, is heated to a high temperature, causing the polynorbornene-based resin (high-Tg resin) to degrade in molecular weight, resulting in yellowing and a decrease in molecular weight of the resin composition. Also, in the next step [B], when the molten film 150 is formed by adjusting its thickness while flattening the molten film 150, the molten film 150 shrinks, which can cause curling. In contrast, as in this embodiment, by including a good 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 (high-Tg 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 flatness and excellent whiteness can be produced.

[0081] The good solvents included in the resin composition are not particularly limited, but examples 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. Those that exhibit excellent solubility in polynorbornene-based resins are used.

[0082] 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 good solvent with high solubility for dissolving the polynorbornene-based resin is preferably selected. Specifically, the Hansen solubility parameter (HSP) distance (Ra) for the polynorbornene-based resin should be 7.00 (J / cm²). 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 good solvent can be said to be capable of dissolving 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.

[0083] In this specification, a good solvent is one that can dissolve polynorbornene-based resins with superior solubility than the poor solvents described later; that is, a solvent whose Hansen solubility parameter (HSP) distance (Ra) to the polynorbornene-based resin is shorter than the HSP distance (Ra) to the poor solvent. Furthermore, the Hansen solubility parameters of solvents (good solvents and poor solvents) in this specification are derived by dividing the solubility parameters introduced by Hildebrand into three components: the dispersion term δD, the polarity term δP, and the hydrogen bonding term δH, and representing them in three-dimensional space.

[0084] 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.)

[0085] 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

[0086] Furthermore, the definition and calculation of HSP are described in Charles M. Hansen's "Hansen Solubility Parameters: A Users Handbook" (CRC Press, 2007).

[0087] 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.

[0088] 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 (good solvent and poor solvent) is (δD2, δP2, δH2).

[0089] HSP distance (Ra)= {4×(δD1-δD2) 2 +(δP1-δP2) 2 +(δH1-δH2) 2} 0.5

[0090] Furthermore, Hansen's HSP values ​​for solvents (good solvents and poor solvents) can be calculated using the following formula, with volume as the mixing ratio.

[0091] [δDm, δPm, δHm] = [(a×(δD1+b×δD2),(a×(δP1+b×δP2),(a×(δH1+b×δH2)] / (a+b)

[0092] Examples of good solvents, that is, 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 a good solvent included in the resin composition is a combination of polynorbornene-based resin and at least one of decane, mesitylene, and toluene.

[0093] Furthermore, the content of the good solvent in the resin composition is preferably set to 5.0% by weight or more and 50.0% by weight or less, more preferably 15.0% by weight or more and 30.0% by weight or less. By setting the content of the good solvent 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 content of the good solvent 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 content of the good solvent in the resin composition is within this range, the storage modulus G' of the resin composition exhibiting a molten or softened state can be reliably set to a value within the following range. Furthermore, during the immersion of the molten film 150 in the poor solvent in the subsequent step [C], a reliable interaction can be created between the good solvent contained in the molten film 150 and the poor solvent. Therefore, since a change is reliably made in the structure of the molten film 150, a molten film 150 composed of a porous material can be reliably formed.

[0094] As mentioned above, because the resin composition contains a good solvent, the heating temperature for heating the resin composition can be set to a temperature that is reliably lower than the softening temperature of the polynorbornene-based resin. However, the heating temperature for heating the resin composition varies depending on the type of polynorbornene-based resin selected, but is generally preferably set in a temperature range of 70°C to 150°C, and more preferably 80°C to 120°C. By setting the heating temperature for heating the resin composition to a molten or softened state within this range, 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 the resin composition is brought to a molten or softened state, a resin film 1 exhibiting excellent whiteness can be obtained.

[0095] 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 good 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 1×10 7 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 range, the molten or softened resin composition can be reliably fed from the opening 241 of the T-die 240 to the film adjustment unit 800 as a molten film 150 in the form of a strip.

[0096] Furthermore, the resin composition containing the polynorbornene resin and a good solvent will exhibit a molten or softened state 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 exhibits a molten or softened state, and can be reliably fed from the opening 241 of the T-die 240 as a strip-shaped molten film 150 to the film adjustment unit 800.

[0097] 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.

[0098] [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 its average thickness is set (adjusted) to a predetermined thickness (adjustment step).

[0099] This results in the formation of a molten film 150 in which a resin composition containing a polynorbornene-based resin and a good solvent is molded into a film.

[0100] 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.

[0101] 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.

[0102] 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 adjusted to the thickness of the resin film 1 to be formed. By appropriately setting these distances to a predetermined size, a molten film 150 of the desired thickness, and consequently the resin film 1, can be obtained.

[0103] Thus, in this process [B], the touch rolls 110, 120, and 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.

[0104] In the planarization of the first surface 15 and the second surface 13 of the molten film 150 using the touch rolls 110, 120, and 130, in this embodiment, a resin composition containing a polynorbornene-based resin and a good solvent is used 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 adjustment unit 800 (touch rolls 110, 120, and 130). Therefore, the planarization 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.

[0105] Furthermore, curling in the molten film 150 occurs frequently when a polynorbornene-based resin, particularly one exhibiting a high Tg with a glass transition temperature of 200°C or higher, is selected, and when a thick molten film 150 is formed, if a good solvent is not included in the resin composition. In such cases, as in this embodiment, by using a resin composition containing a polynorbornene-based resin and a good solvent, the occurrence of curling can be accurately suppressed or prevented. 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].

[0106] Furthermore, in step [B], when molding the molten film 150 (resin composition), it is preferable to remove a portion of the good solvent contained in the molten film 150 by heating the molten film 150 (resin composition).

[0107] 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.

[0108] In step [B], the heating temperature for heating the molten film 150 (resin composition) is preferably set to about 80°C to 160°C, more preferably to about 100°C to 140°C. This ensures that a portion of the good solvent contained in the molten film 150 is reliably removed from the molten film 150.

[0109] Furthermore, by removing this good solvent, the content of the good solvent in the molten film 150, that is, the amount of good solvent remaining in the resin composition, is preferably set to about 0.5% by weight or more and 3.0% by weight or less, and more preferably to about 1.0% by weight or more and 2.0% by weight or less. This ensures that when the molten film 150 (resin composition) is immersed in the poor solvent in the next step [C], a structural change in the molten film 150 can be reliably caused by the interaction between the poor solvent and the good solvent contained in the molten film 150, thereby reliably forming a porous structure in the molten film 150.

[0110] In this embodiment, the molding process is configured in which a resin composition containing a polynorbornene-based resin and a good solvent is formed into a molten film 150 in the form of a film, by the process [A] (extrusion process) and the process [B] (adjustment process). However, this molding process is not limited to the process consisting of these extrusion process (extrusion step) and adjustment process (adjustment step). That is, any process that can form a molten film 150 in the form of a film using a resin composition containing a polynorbornene-based resin and a good solvent may be a process to which various methods such as the inflation method, calendering method, or casting method are applied. However, by configuring the molding process to form the molten film 150 in the process consisting of these extrusion process and adjustment process, as described above, the effect of being able to manufacture a resin film 1 that is mainly made of a polynorbornene-based resin and has a white color at a low cost, and furthermore, the effect of being able to manufacture a resin film 1 that has excellent flatness and exhibits excellent whiteness is obtained.

[0111] [C] Next, the molten film 150, which is a resin composition in a molten or softened state and whose first surface 15 and second surface 13 have been flattened and adjusted to a predetermined thickness, is immersed in a poor solvent in which the solubility of the polynorbornene-based resin is lower than that of a good solvent (immersion step).

[0112] As a result, an interaction occurs between the good solvent and the poor solvent contained in the molten film 150, causing a change in the structure of the molten film 150, thus forming a porous structure in the molten film 150. In other words, a molten film 150 composed of a porous material is formed. Therefore, the resin film 1 obtained in the next step [D] is composed of a porous material having multiple fine pores, and based on this porous material composition, it can exhibit a white color.

[0113] This immersion process is carried out by transporting the molten film 150 (resin composition) between the touch roll 130 and the winding roller 46 to the film immersion section 900 located upstream of the film drying section 600. This transport of the molten film 150 to the film immersion section 900 causes the molten film 150, which is folded and wrapped around the immersion roll 91, to pass through the immersion tank 92, thereby immersing the molten film 150 in the poor solvent. As a result, the interaction between the good solvent contained in the molten film 150 and the poor solvent causes a change in the structure of the molten film 150, forming a porous structure. That is, a molten film 150 exhibiting a white color is formed based on its porous composition.

[0114] As a poor solvent in which the molten film 150 is immersed, for example, one similar to the good solvent described above can be used, in which the solubility of polynorbornene-based resin is lower than that of the good solvent.

[0115] This poor solvent has a Hansen solubility parameter (HSP) distance (Ra) of 10.00 (J / cm) for polynorbornene-based resins. 3 ) 0.5 Preferably, it is 12.00 (J / cm²). 3 ) 0.5 It is more preferable that the value is greater than or equal to 13.00 (J / cm²). 3 ) 0.5More preferably, the above conditions are met, and among these, a good solvent and a poor solvent are selected in which they do not separate when mixed in any ratio. Such a poor solvent can be said to be one in which the solubility of polynorbornene-based resin is lower than that of the good solvent. By selecting such a poor solvent in which they do not separate when mixed with the good solvent in any ratio, a more reliable interaction can be established between the good solvent and the poor solvent, thereby more reliably forming the molten film 150 composed of a porous material.

[0116] Examples of such poor solvents include, for instance, when a polynorbornene-based resin is selected as the thermoplastic resin, at least one of acetone (boiling point 56.0°C), methanol (boiling point 64.7°C), and cyclohexanone (boiling point 155.6°C). In other words, when a polynorbornene-based resin is selected as the thermoplastic resin, a combination of a good solvent and a poor solvent would be at least one of decane, mesitylene, cyclohexane, and toluene, and at least one of acetone, methanol, and cyclohexanone.

[0117] Furthermore, it is preferable that the poor solvent has a boiling point lower than that of the good solvent, and more preferably within a range of 50°C to 150°C lower than that of the good solvent. This allows the heating temperature to be set lower when drying the molten film 150 (resin composition) by heating in the next step [D], thereby more efficiently removing the mixed solvent of the good solvent and the poor solvent remaining on the molten film 150. In other words, the drying of the molten film 150 by heating can be carried out at a lower temperature. As a result, the removeability of the mixed solvent from the molten film 150, in other words, the drying performance, is improved.

[0118] Furthermore, in step [C], the immersion time for immersing the molten film 150 (resin composition) in the poor solvent is preferably set to about 3 seconds to 30 seconds, more preferably to about 5 seconds to 10 seconds. This makes it possible to more reliably form a porous molten film 150 by immersing the molten film 150 (resin composition) in the poor solvent.

[0119] Furthermore, in step [C], the temperature of the molten film 150 (resin composition) when it is immersed in the poor solvent, i.e., the temperature of the poor solvent, is preferably set to about 10°C to 50°C, more preferably to about 20°C to 40°C. This makes it possible to more reliably form a molten film 150 composed of a porous material by immersing the molten film 150 (resin composition) in the poor solvent.

[0120] [D] Next, the molten or softened resin composition is heated to dry the molten film 150, which has been made into a porous body (drying step).

[0121] As a result, the resin film 1, in which the resin composition is formed into a strip-shaped film, is composed of a porous material having multiple fine pores, and based on this, it can be obtained to exhibit a white color.

[0122] This drying process is carried out by transporting the molten film 150, which has been made porous from the resin composition, between the touch roll 130 and the winding roller 46, to the film drying section 600 located upstream of the film immersion section 900. 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 mixed solvent of good solvent and poor 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.

[0123] At this time, the molten film 150 is composed of a porous body due to immersion in a poor solvent in step [C], and in step [D], the molten film 150 is heated and dried while maintaining this state to form the resin film 1. Therefore, the resin film 1 formed by heating and drying is composed of a porous body containing polynorbornene-based resin as the main material and having multiple fine pores, and furthermore, based on being composed of this porous body, it can be obtained to exhibit a white color.

[0124] Furthermore, this resin film 1 is formed through the processes [A] to [D] described above, satisfying the requirement of a whiteness of 70 to 130 according to ASTM E313. As a result, the resin film 1, which is composed of a porous material, has multiple fine pores (perforations), and consequently exhibits an excellent white color.

[0125] In this way, by constructing the resin film 1 as a porous material, it is possible to make it appear white in color. Therefore, the resin film 1 can appear white in color without containing a white coloring agent.

[0126] Here, the whiteness (WI) defined in ASTM E313 is an index that indicates the degree of whiteness when ideal white (perfect diffuse reflectance surface) is set to 100%. The smaller the whiteness, the darker the color, and the larger the whiteness, the brighter the color. In other words, as the color moves away from ideal white, the whiteness value becomes smaller or larger than 100. Therefore, it can be said that the resin film 1 exhibits excellent whiteness as a color tone by satisfying the requirement that the whiteness is between 70 and 130, preferably between 80 and 120, and more preferably between 90 and 110.

[0127] Furthermore, when the average thickness of the resin film 1 is 0.2 mm, it is preferable that the total light transmittance of visible light with wavelengths of 400 nm to 780 nm is 10.0% or less, and more preferably 0.0% to 5.0%.

[0128] Furthermore, when the resin film 1 has an average thickness of 0.2 mm, it is preferable that the total light reflectance of visible light with wavelengths of 400 nm to 780 nm is 50.0% or more, and more preferably 80.0% to 100.0%.

[0129] By setting the total light transmittance to be below the upper limit and the total light reflectance to be above the lower limit, the light incident on the resin film 1 is reflected more efficiently, and the resin film 1 can be said to exhibit a superior white color. Therefore, this resin film 1 can be suitably used as a light-reflecting film such as a back-light reflective film in a surface light source device of an organic EL display or liquid crystal display, a back-light reflective film in an illuminated sign, or a back-light reflective film in a solar cell.

[0130] Furthermore, as described above, the resin film 1 is composed of a porous material and therefore exhibits a white color. This porous resin film 1 contains pores with a diameter of preferably 5 μm or less, more preferably 3 μm or less, in a cross-section formed by cutting it in the thickness direction, and in addition, in the scattering image obtained by small-angle X-ray scattering measurement (SAXS), when the magnitude of the scattering vector is denoted as q, the magnitude of the scattering vector q is 0.05 nm. -1 More than 0.5nm -1 Within the following range, the small-angle X-ray scattering intensity I(q) is q -4It is preferable that the property of being proportional to the given value is satisfied. This means that the resin film 1, which is composed of a porous material, can be said to be a porous material in which a plurality of fine pores (perforations) are formed, and furthermore, these pores are uniformly dispersed. As a result, the resin film 1 can be made to exhibit a whiter color. Here, the scattering image of the resin film 1 obtained by small-angle X-ray scattering measurement (SAXS) can be obtained, for example, by preparing a test piece (width 10 mm × length 10 mm) made of the resin film 1, and measuring this test piece using a Pilatus 1M detector at a synchrotron radiation facility beamline (for example, SPring-8 BL03XU beamline second hutch) under conditions such as an X-ray wavelength of 0.1 nm and camera distances of 4 m and 1 m. The magnitude q of the scattering vector can be expressed as q = (4π / λ)sin(2θ / 2), where the X-ray wavelength is λ and the X-ray scattering angle is 2θ.

[0131] 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 the mixed solvent of good solvent and poor solvent remaining in the molten film 150 is reliably removed from the molten film 150, thereby obtaining the resin film 1.

[0132] By following the above process, a resin film 1 composed of a porous body mainly containing polynorbornene resin can be manufactured that satisfies the requirement of having a whiteness of 70 to 130 according to ASTM E313.

[0133] The resin film of the present invention has been described above, but the present invention is not limited thereto.

[0134] 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 made of polynorbornene-based resin and exhibiting a white color, it is not limited to this, and may be composed of a laminate in which other layers are laminated onto this single layer body.

[0135] Furthermore, in the method for manufacturing the resin film of the present invention, one or more steps can be added for any purpose. [Examples]

[0136] 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.

[0137] 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.

[0138] (PNB resin 1) As PNB-based resin 1, hexylnorbornene (HexylNB) homopolymer (manufactured by Promerus, glass transition temperature: 221°C, weight-average molecular weight (Mw): 2.7 × 10⁻⁶) is used. 5 A solution was prepared (g / mol, with a yellowing onset temperature of 195°C and a molecular weight decrease onset temperature of 240°C).

[0139] (PNB resin 2) As PNB-based resin 2, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 50:50, glass transition temperature: 259°C, weight-average molecular weight (Mw): 1.3 × 10⁻⁶) 5 A solution was prepared (g / mol, with a yellowing onset temperature of 195°C and a molecular weight decrease onset temperature of 240°C).

[0140] (PNB resin 3) As PNB-based resin 3, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 80:20, glass transition temperature: 270°C, weight-average molecular weight (Mw): 1.6 × 10⁻⁶) 5 A solution was prepared (g / mol, with a yellowing onset temperature of 195°C and a molecular weight decrease onset temperature of 240°C).

[0141] (PNB resin 4) As PNB-based resin 4, hexylnorbornene (HexylNB) homopolymer (manufactured by Promerus, glass transition temperature: 240°C, weight-average molecular weight (Mw): 1.7 × 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.

[0142] (PNB resin 5) As PNB-based resin 5, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 50:50, glass transition temperature: 263°C, weight-average molecular weight (Mw): 2.1 × 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.

[0143] (PNB resin 6) As PNB-based resin 6, 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.

[0144] (PNB resin 7) As PNB-based resin 7, 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.

[0145] (PNB resin 8) As PNB-based resin 8, norbornene (NB)-ethylidene norbornene (EthylidenelNB) copolymer (manufactured by Promerus, NB:EthylidenelNB = 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.

[0146] (PNB resin 9) As PNB-based resin 9, 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.

[0147] (PNB resin 10) As PNB-based resin 10, ethylidene norbornene homopolymer (manufactured by Promerus, glass transition temperature: 352°C, weight-average molecular weight (Mw): 2.0 × 10) is used. 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.

[0148] (PNB resin 11) As PNB-based resin 11, norbornene (NB)-ethylidene norbornene (EthylidenelNB) copolymer (manufactured by Promerus, NB:EthylidenelNB = 50:50, glass transition temperature: 337°C, weight-average molecular weight (Mw): 1.3 × 10⁻⁶) is used. 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.

[0149] (PNB resin 12) As PNB-based resin 12, norbornene (NB)-ethylidene norbornene (EthylidenelNB) copolymer (manufactured by Promerus, NB:EthylidenelNB = 95:5, glass transition temperature: 312°C, weight-average molecular weight (Mw): 1.5 × 10⁻⁶) is used. 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.

[0150] (PNB resin 13) As PNB-based resin 13, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 80:20, glass transition temperature: 294°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.

[0151] (PNB resin 14) As PNB-based resin 14, norbornene (NB)-hexylnorbornene (HexylNB) copolymer (manufactured by Promerus, NB:HexylNB = 95:5, glass transition temperature: 310°C, weight-average molecular weight (Mw): 1.6 × 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.

[0152] (Good solvent 1) Toluene (manufactured by Kanto Chemical Co., Ltd., "40180-01", boiling point: 110.7°C) was prepared as a good solvent 1.

[0153] (Poor solvent 1) As the poor solvent 1, acetone (manufactured by Kanto Chemical Co., Ltd., boiling point: 56.1°C) was prepared.

[0154] 1. Formation of resin film [Example 1] [1] First, a resin composition was prepared by stirring and mixing PNB resin 1 (HexylNB homopolymer) and good solvent 1 (toluene) so that their respective contents were 70% by weight and 30% by weight.

[0155] Furthermore, the Hansen solubility parameter (HSP) distance (Ra) of good solvent 1 (toluene) to PNB resin 1 (HexylNB homopolymer) was calculated using the calculation software HSPiP 5th edition (available from http: / / pirika.com / JP / HSP / index-j.html) and was found to be 2.0 (J / cm²). 3 ) 0.5 That was the case.

[0156] Furthermore, the storage modulus G' of the resin composition at 100°C was measured using a dynamic viscoelasticity analyzer (DMA, Anton Paar, "MCR302") under the conditions of a heating rate of 5°C / min, a temperature range of 25°C to 150°C, and an angular frequency of 1 Hz, and was found to be 1.0 × 10⁻⁶. 4 It was Pa.

[0157] [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. Then, under conditions of a rotation speed of 70 rpm, a heating temperature of 100°C, and a kneading time of 1 minute, the PNB-based resin 1 (HexylNB homopolymer) and a good solvent 1 (toluene) were kneaded in the resin composition by the kneader 230. 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 adjustment section 800.

[0158] [3] Next, the molten film 150, which is in the form of a film and was extruded from the opening 241, was sandwiched between the touch roll 110 and the touch roll 120, and between the touch roll 120 and the touch roll 130, thereby flattening the first surface 15 and the second surface 13 of the molten film 150, and the solvent was removed from the molten film 150 by heating the molten film 150 with the touch rolls 110 to 130 until the solvent remaining in the molten film 150 was 10%.

[0159] [4] Next, the molten film 150 was supplied to the film immersion section 900 and immersed in the poor solvent 1 (acetone) stored in the immersion tank 92, thereby making the molten film 150 a porous material. The immersion time of the molten film 150 in the poor solvent 1 (acetone) stored in the immersion tank 92 was set to 10 seconds, and the temperature of the poor solvent 1 (acetone) stored in the immersion tank 92 was set to 25°C. Furthermore, the distance (Ra) of the Hansen solubility parameter (HSP) of the poor solvent 1 (acetone) to the PNB resin 1 (HexylNB homopolymer) was calculated using the calculation software HSPiP 5th edition (obtained from http: / / pirika.com / JP / HSP / index-j.html) and was found to be 13.2 (J / cm). 3 ) 0.5 That was the case.

[0160] [5] Next, the molten film 150 composed of this porous material 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 200 μm.

[0161] [Examples 2-3] Except for changing the type of polynorbornene-based resin contained in the resin composition in the above step [1] as shown in Table 1, resin films 1 of Examples 2 to 3 were obtained in the same manner as in Example 1.

[0162] [Examples 4-14] In step [1] described above, the type of polynorbornene-based resin contained in the resin composition was changed as shown in Table 1, and the respective contents of the resin and the good solvent were changed to 50% by weight and 50% by weight, respectively. Otherwise, resin films 1 of Examples 4 to 14 were obtained in the same manner as in Examples 1 to 3.

[0163] [Comparative Examples 1-14] In the above step [4], the supply of the molten film 150 to the film immersion section 900 was discontinued, thereby omitting the immersion of the molten film 150 in the poor solvent 1 (acetone). Except for this, the resin films 1 of Comparative Examples 1 to 14 were obtained in the same manner as in Examples 1 to 14.

[0164] 2. Evaluation The resin film 1 of each example and each comparative example was evaluated by the following method.

[0165] <Measurement test of whiteness (WI)> For each example and comparative example, the whiteness (WI) of resin film 1 was measured in accordance with ASTM E313 using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation, "V-670"), with the measurement conditions being: measurement light source: D65, observation conditions: 10° field of view.

[0166] <Measurement test of total light transmittance and total light reflectance> For each example and comparative example, a resin film 1 with an average thickness of 0.2 mm was prepared, and then the total light transmittance and total light reflectance of visible light with wavelengths between 400 nm and 780 nm were measured in the thickness direction using a UV-Vis spectrophotometer (Shimadzu Corporation, "UV-2600i").

[0167] <Observation test of voids in the cross-section> For each example and comparative example, a cross-section of resin film 1 was formed by cutting it in the thickness direction. This cross-section was then photographed using an electron microscope (JEOL Ltd., "JSM-7401F FE-SEM") to observe the structure of the pores present in the cross-section of resin film 1. For reference, Figure 3 shows an electron microscope image of a magnified view of the cross-section of resin film 1 from Example 1. Based on the electron microscope images of the cross-sections of resin film 1 from each example and comparative example, the diameter (μm) of the pores present in the cross-section was measured and evaluated as follows.

[0168] ◎: Vacuums with a diameter of 3 μm or less are observed in the cross-section. ○: Vacuums with a diameter of 5 μm or less are observed in the cross-section. ×: No voids with a diameter of 5 μm or less were observed in the cross-section.

[0169] <Small-angle X-ray scattering measurement test> For each example and comparative example of resin film 1, a test specimen (10 mm wide x 10 mm long) made of resin film 1 was prepared, and the scattering image of resin film 1 was obtained by measuring this test specimen using a Pilatus 1M detector at a synchrotron radiation facility beamline (e.g., SPring-8 BL03XU beamline second hutch) under conditions such as an X-ray wavelength of 0.1 nm and camera distances of 4 m and 1 m.

[0170] Then, in the scattering image, the relationship between the magnitude of the scattering vector q and the small-angle X-ray scattering intensity I(q) was determined and evaluated as follows. The magnitude of the scattering vector q can be expressed as q = (4π / λ)sin(2θ / 2)[1 / nm], where the X-ray wavelength is λ and the X-ray scattering angle is 2θ. For reference, Figure 4 shows graphs representing the relationship between the magnitude of the scattering vector q and the small-angle X-ray scattering intensity I(q) in the scattering images of resin film 1 of Example 1 and Comparative Example 1.

[0171] The magnitude q of the scattering vector is 0.05 nm. -1 More than 0.5nm -1 Within the following size range, ○: Small-angle X-ray scattering intensity I(q) is q -4 It is proportional to. ×: Small-angle X-ray scattering intensity I(q) is q -4 It is not proportional.

[0172] <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.

[0173] <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.

[0174] 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.

[0175] ◎: 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.

[0176] <Molecular weight reduction test> The weight-average molecular weight (Mw) of the polynorbornene-based resin contained in resin film 1 of each example and comparative example was obtained by creating a calibration curve for polystyrene standard substances using gel permeation chromatography (GPC) and calculating the weight-average molecular weight (Mw) using this calibration curve.

[0177] 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 evaluated as follows.

[0178] ◎: 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 molecular weight is clearly observed when the Mw decrease rate is 10.0% or higher.

[0179] <Curl Test> For each example and comparative example, the presence or absence of curling in the resin film 1 was visually observed.

[0180] Then, based on the observed curl state, the resin film 1 of each example and comparative example was evaluated as follows.

[0181] ◎: 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.

[0182] The evaluation results for the resin films obtained in each example and comparative example as described above are shown in Tables 1 and 2 below.

[0183] [Table 1]

[0184] [Table 2]

[0185] In each embodiment, as shown in Table 1, it was found that by immersing the molten film 150 in a poor solvent in step [4], the molded resin film 1 can be formed as a porous body exhibiting whiteness that satisfies the requirement of a whiteness of 70 or more and 130 or less according to ASTM E313.

[0186] In contrast, in each comparative example, as shown in Table 2, the immersion of the molten film 150 in the poor solvent 1 in step [4] was omitted, and as a result, the molded resin film 1 could not be made of a porous body exhibiting white color. [Explanation of Symbols]

[0187] 1. Resin film 13 Side 2 15 Page 1 41 Conveyor rollers 46 Winding roller 61 Hot air supply section 91 Immersion Roll 92 Soaking tank 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 adjustment section 900 Film immersion section

Claims

1. A resin film composed primarily of polynorbornene-based resin, A resin film characterized by having a whiteness of 70 or more and 130 or less according to the provisions of ASTM E313.

2. The resin film according to claim 1, wherein, when the average thickness of the resin film is 0.2 mm, the total light transmittance of visible light with wavelengths of 400 nm to 780 nm is 10.0% or less.

3. The resin film according to claim 2, wherein, when the average thickness of the resin film is 0.2 mm, the total light reflectance of visible light with wavelengths of 400 nm to 780 nm is 50.0% or more.

4. The resin film is the resin film according to claim 1, wherein the resin film does not contain a white coloring agent.

5. The resin film is a porous resin film as described in claim 1.

6. The resin film, in a cross-section formed by cutting it in the thickness direction, contains pores with a diameter of 5 μm or less, and in the scattering image obtained by small-angle X-ray scattering measurement (SAXS), when the magnitude of the scattering vector is q, the magnitude of the scattering vector q is 0.05 nm. －１ 0.5nm or more －１ Within the following range, the small-angle X-ray scattering intensity I(q) is q －４ A resin film according to claim 5, proportional to [a certain value].

7. The resin film according to claim 1, wherein the relative permittivity at a frequency of 10 GHz is less than 2.

0.

8. The resin film has a dielectric loss tangent of 5.0 × 10 at a frequency of 10 GHz. －４ The resin film according to claim 1, which is less than [amount missing].

9. 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.

10. The resin film according to claim 1, wherein the polynorbornene-based resin has a glass transition temperature of 200°C or higher.

11. Claim 10, wherein the polynorbornene-based resin is represented by the following general formula (1). The resin film described above. 【Chemistry 1】 [In the general formula (1) 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.]

Images