Semi-aromatic polyamide film and method for producing the same

Abstract

This invention provides a semi-aromatic polyamide film with sufficiently small relaxation amount. The semi-aromatic polyamide film of this invention is a rectangular semi-aromatic polyamide film having an edge along the MD direction and an edge along the TD direction, the refractive index difference n calculated by the following formula (1) D The range is -0.0010 to 0.0045. The refractive index difference n D ={(n C -n L ) - (n C -n R )} / 2 (1) (where n C n is the refractive index along the MD direction at the central part of the film. L n is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film. R (Refractive index in the MD direction at a position 10% inside the film width from the right end of the film).

Description

Technical Field

[0001] This invention relates to a semi-aromatic polyamide film with suppressed relaxation (Japanese: たるみ), a method for manufacturing the same, and electronic materials and optical components having the above-mentioned semi-aromatic polyamide film. Background Technology

[0002] Semi-aromatic polyamide films stretched along both the MD (length) and TD (width) directions exhibit excellent heat resistance and mechanical properties, making them suitable for various applications. Among the semi-aromatic polyamides constituting these films, polyamide 9T, composed of an aliphatic diamine with 9 carbon atoms and terephthalic acid, and polyamide 10T, composed of an aliphatic diamine with 10 carbon atoms and terephthalic acid, particularly demonstrate superior heat resistance and mechanical properties.

[0003] Patent Document 1 discloses a biaxially stretched film, which is a film containing a semi-aromatic polyamide resin, obtained by biaxially stretching an unstretched film with specific crystallization heat. However, the film disclosed in Patent Document 1 has a large slack, which can cause wrinkles during winding or serpentine movement during travel.

[0004] On the other hand, Patent Document 2 discloses a film comprising an aliphatic polyamide resin, wherein the relaxation amount can be controlled by the cooling rate of the film after biaxial stretching and heat-fixing; if the cooling rate is reduced, the relaxation amount decreases. However, the film disclosed in Patent Document 2 is prone to deformation when exposed to high temperatures.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2020 / 230806

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-297415 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Furthermore, in order to control the relaxation amount of the semi-aromatic polyamide film disclosed in Patent Document 1, the inventors applied the method described in Patent Document 2, but were unable to sufficiently reduce the relaxation amount.

[0011] In addition, in recent years, optical films for display components and the like have been required to have dimensional stability that does not deform even when exposed to high temperatures during transportation or heat treatment.

[0012] The purpose of this invention is to provide a semi-aromatic polyamide film with sufficiently small relaxation amount.

[0013] Another object of the present invention is to provide a semi-aromatic polyamide film with sufficiently small relaxation and excellent dimensional stability under high temperature conditions.

[0014] Another object of the present invention is to provide a method for manufacturing a semi-aromatic polyamide film with sufficiently small relaxation amount.

[0015] Another object of the present invention is to provide electronic materials and optical components having the above-mentioned semi-aromatic polyamide film.

[0016] Methods for solving problems

[0017] To address the aforementioned issues, the inventors conducted in-depth research and discovered that by preheating an unstretched film or a uniaxially stretched film in the MD direction at a specific temperature followed by stretching, and then cooling it at a specific temperature after stretching, the refractive index in the MD direction of the central, left, and right portions of the resulting film in the TD direction can be adjusted to a specific range, thus significantly reducing the relaxation amount. Furthermore, it was found that by preheating an unstretched film or a uniaxially stretched film in the MD direction at a specific temperature followed by stretching, then heat-fixing it at a specific temperature after stretching, and finally cooling it at a specific temperature, the relaxation amount of the resulting film can be significantly reduced, and the dimensional stability under high-temperature conditions can be improved.

[0018] This invention is based on the above insights.

[0019] That is, the present invention provides a semi-aromatic polyamide film, which is a rectangular semi-aromatic polyamide film having an edge along the MD direction and an edge along the TD direction.

[0020] The refractive index difference n calculated from the following formula (1) D It ranges from -0.0010 to 0.0045.

[0021] Refractive index difference n D ={(n C -n L ) - (n C -n R )} / twenty one)

[0022] (where n) C n is the refractive index along the MD direction at the central part of the film. L n is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film. R The refractive index is given in the MD direction at a position 10% inside the film width from the right end of the film. It should be noted that the central, left, and right ends are located on a line parallel to the TD direction of the film.

[0023] The present invention also provides the above-mentioned semi-aromatic polyamide film, wherein the average refractive index n is calculated by the following formula (2). Av The range is 1.5985 to 1.6045.

[0024] Average refractive index n Av = (n C +n L +n R ) / 3 (2)

[0025] (where n) C n L and n R Same as above.

[0026] The present invention also provides the above-mentioned semi-aromatic polyamide film, wherein the relaxation amount, as determined by the following measurement method, is less than 3.0‰.

[0027] <Methods for determining relaxation amount>

[0028] From one end of the TD direction to the other end, measure the length in the MD direction at 50mm scale, and calculate the relaxation amount based on the maximum and minimum values ​​of the above length and the following formula (3).

[0029] Relaxation amount (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3)

[0030] The present invention also provides the above-mentioned semi-aromatic polyamide film, wherein the thermal shrinkage rate S in the MD direction is determined by measuring its dimensions after being placed in an atmosphere at 250°C for 5 minutes and then placed in an atmosphere at 23°C and 50%RH for 2 hours. MD and thermal shrinkage rate S in the TD direction TD The percentages are -1.0% to 1.5%.

[0031] The present invention also provides a method for manufacturing a semi-aromatic polyamide film, which obtains the above-mentioned semi-aromatic polyamide film by means of the following steps [1] or [2].

[0032] [1] The process of preheating the unstretched semi-aromatic polyamide film at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the glass transition temperature Tg of the semi-aromatic polyamide, the process of simultaneously stretching it in the MD and TD directions, and the process of cooling it at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide.

[0033] [2] The process of preheating the uniaxially stretched film of semi-aromatic polyamide in the MD direction at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the Tg of the semi-aromatic polyamide, the process of stretching in the TD direction, and the process of cooling at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide.

[0034] The present invention also provides electronic materials having the above-described semi-aromatic polyamide film.

[0035] The present invention also provides an optical component having the above-described semi-aromatic polyamide film.

[0036] Invention Effects

[0037] According to the present invention, a semi-aromatic polyamide film with sufficiently small relaxation (or with sufficiently small relaxation and excellent dimensional stability even at high temperature of 250°C) can be provided.

[0038] The semi-aromatic polyamide film of the present invention can be suitably used as a base film, cover film and other electronic materials for flexible printed circuit boards; optical materials such as substrates for displays; heat-resistant tapes, etc. Attached Figure Description

[0039] Figure 1 This diagram illustrates the method for measuring the amount of relaxation by taking the case of end relaxation as an example. Detailed Implementation

[0040] [Semi-aromatic polyamide film]

[0041] The semi-aromatic polyamide film of the present invention is a rectangular semi-aromatic polyamide film having an edge along the MD direction and an edge along the TD direction, and is a film containing at least semi-aromatic polyamide as a resin component.

[0042] Semi-aromatic polyamides

[0043] In semi-aromatic polyamides, the monomer components (in other words, the constituent components derived from monomers) include dicarboxylic acid components (in other words, the constituent components derived from dicarboxylic acid) and diamine components (in other words, the constituent components derived from diamine). Furthermore, the dicarboxylic acid component contains at least an aromatic dicarboxylic acid component, and the diamine component contains at least an aliphatic diamine component.

[0044] In addition to dicarboxylic acid and diamine, semi-aromatic polyamides may also contain other components. In order to obtain a film with excellent heat resistance and low water absorption, the total content of dicarboxylic acid and diamine is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0045] In addition to aromatic dicarboxylic acid components and aliphatic diamine components, semi-aromatic polyamides may also contain other components. In order to obtain a film with excellent heat resistance and low water absorption, the total content of aromatic dicarboxylic acid components and aliphatic diamine components is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0046] The dicarboxylic acid that forms the above-mentioned dicarboxylic acid component contains at least an aromatic dicarboxylic acid, and the diamine that forms the above-mentioned diamine component contains at least an aliphatic diamine.

[0047] Regarding the aforementioned aromatic dicarboxylic acids, those with excellent heat resistance and low water absorption are preferably those containing 60 mol% or more of terephthalic acid, more preferably 70 mol% or more, and even more preferably 85 mol% or more.

[0048] Examples of aromatic dicarboxylic acids other than terephthalic acid include isophthalic acid and naphthalic acid. Furthermore, naphthalic acid includes 1,2-form, 1,3-form, 1,4-form, 1,5-form, 1,6-form, 1,7-form, 1,8-form, 2,3-form, 2,6-form, and 2,7-form.

[0049] In addition to aromatic dicarboxylic acids, other dicarboxylic acids may be included without impairing the effects of the present invention. Examples of other dicarboxylic acids include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanoic acid, tetradecanoic acid, and octadecanoic acid.

[0050] The aforementioned aliphatic diamine preferably comprises an aliphatic diamine having 6 to 12 carbon atoms as its main component. The content of aliphatic diamines having 6 to 12 carbon atoms in the total aliphatic diamine content is preferably 60 mol% or more, more preferably 75 mol% or more, and even more preferably 90 mol% or more. When the content of aliphatic diamines having 6 to 12 carbon atoms is 60 mol% or more, the resulting membrane can balance heat resistance and productivity. Aliphatic diamines having 6 to 12 carbon atoms can be used alone or in combination with two or more. It should be noted that when two or more are used in combination, the above content refers to their total content.

[0051] Examples of aliphatic diamines with 6 to 12 carbon atoms include straight-chain aliphatic diamines such as 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine; and branched-chain aliphatic diamines such as 2-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, 2,2,4- / 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 2-methyl-1,6-hexanediamine, and 2-methyl-1,7-heptanediamine.

[0052] Regarding the aforementioned aliphatic diamines, among aliphatic diamines with 6 to 12 carbon atoms, it is more preferable to have an aliphatic diamine with 9 to 12 carbon atoms as the main component, and even more preferably polyamide 9T with an aliphatic diamine with 9 carbon atoms as the main component or polyamide 10T with an aliphatic diamine with 10 carbon atoms as the main component.

[0053] In addition to aliphatic diamines with 6 to 12 carbon atoms, the aforementioned aliphatic diamines may also contain (linear) aliphatic diamines with 6 or fewer carbon atoms, such as 1,4-butanediamine and 1,5-pentanediamine.

[0054] In addition to aliphatic diamines, the diamines forming the diamine component may also contain other diamines without impairing the effects of the present invention. Examples of other diamines include alicyclic diamines such as isophorone diamine, norbornene dimethylamine, and tricyclodecane dimethylamine; and aromatic diamines such as m-phenylenediamine, p-phenylenediamine, m-phenylenediamine, and p-phenylenediamine.

[0055] Without impairing the effects of the present invention, semi-aromatic polyamides may contain lactam units such as ε-caprolactam, ζ-heptanolactam, η-octanolactam, and ω-laurolactam (in other words, constituent units derived from lactams) as monomer units.

[0056] The types and copolymerization ratios of the monomer components constituting the semi-aromatic polyamide are preferably selected such that the melting point (Tm) of the resulting semi-aromatic polyamide is in the range of 270–350°C. With a Tm below 350°C, the semi-aromatic polyamide can effectively suppress thermal decomposition during film formation. Furthermore, with a Tm above 270°C, films with excellent heat resistance can be formed.

[0057] The limiting viscosity of the semi-aromatic polyamide is preferably 0.8 to 2.0 dL / g, more preferably 0.9 to 1.8 dL / g. When the limiting viscosity of the semi-aromatic polyamide is 0.8 dL / g or higher, the membrane productivity is excellent, and membranes with excellent mechanical strength can be manufactured.

[0058] <Other Ingredients>

[0059] The semi-aromatic polyamide film of the present invention contains at least a semi-aromatic polyamide as a resin component. The semi-aromatic polyamide film of the present invention may also contain resins other than semi-aromatic polyamide as a resin component. From the viewpoint of improving heat resistance and transparency, the proportion of semi-aromatic polyamide in the total resin component is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0060] In addition to the resin component, the semi-aromatic polyamide film of the present invention may contain other components as needed. Examples of other components include polymerization catalysts (phosphoric acid, phosphorous acid, hypophosphoric acid and their salts), capping agents (acetic acid, lauric acid, benzoic acid, octylamine, cyclohexylamine, aniline, etc.), and additives described later.

[0061] Semi-aromatic polyamide membrane

[0062] The refractive index difference n of the semi-aromatic polyamide film of the present invention, calculated by the following formula (1), is... D The range is -0.0010 to 0.0045. From the perspective of suppressing relaxation, the above refractive index difference n D Preferably, it is -0.0005 to 0.0040, more preferably 0.0000 to 0.0035, and most preferably 0.0010 to 0.0029.

[0063] Refractive index difference n D ={(n C -n L ) - (n C -n R )} / twenty one)

[0064] (where n) Cn is the refractive index along the MD direction at the central part of the film. L n is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film. R The refractive index is given in the MD direction at a position 10% inside the film width from the right end of the film. It should be noted that the central, left, and right ends are located on a line parallel to the TD direction of the film.

[0065] Furthermore, from the viewpoint of suppressing relaxation, the average refractive index n of the semi-aromatic polyamide film of the present invention, calculated by the following formula (2), is... Av Preferably, the value is 1.5985 to 1.6045, more preferably 1.5989 to 1.6040, and particularly preferably 1.5993 to 1.6036.

[0066] Average refractive index n Av = (n C +n L +n R ) / 3 (2)

[0067] (where n) C n L and n R Same as above.

[0068] The semi-aromatic polyamide film of the present invention has a refractive index difference n D For the above range (preferably refractive index difference n) D and the average refractive index n Av Within the aforementioned range, the occurrence of relaxation can be suppressed, and the relaxation amount of the film can be reduced to 3.0‰ or less. This prevents wrinkles from forming during winding onto the winding roller, or from causing defects due to wrinkles during secondary processing after the film is pulled out from the roller. The relaxation amount of the semi-aromatic polyamide film of the present invention is, for example, 3.0‰ or less, preferably 2.5‰ or less, more preferably 2.0‰ or less, further preferably 1.5‰ or less, and most preferably 1.0‰ or less.

[0069] The aforementioned relaxation amount is determined by the following measurement method. It should be noted that, in this invention, when the relaxation location (i.e., the location where the length in the MD direction is the largest) is located within 80% of the center in the TD direction of the membrane, it is called "mid-range relaxation," and when it is located within 10% of both ends in the TD direction of the membrane, it is called "end relaxation."

[0070] <Methods for determining relaxation amount>

[0071] In the case where the semi-aromatic polyamide membrane is in the form of a membrane roll formed by winding the membrane, one circumference of the surface layer is cut from the membrane roll with an outer diameter of 300 mm or more and used as a sample. From one end of the obtained sample along the TD direction to the other end, the length in the MD direction is measured at 50 mm scale, and the relaxation amount is calculated based on the maximum and minimum values ​​of the above length and by the following formula (3).

[0072] It should be noted that when the semi-aromatic polyamide film is in the form of a single sheet, the length in the MD direction is measured from one end to the other along the TD direction with a 50mm scale. The relaxation amount is calculated based on the maximum and minimum values ​​of the above length and by the following formula (3).

[0073] Relaxation amount (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3)

[0074] Furthermore, the semi-aromatic polyamide film of the present invention exhibits excellent dimensional stability under high-temperature conditions. The thermal shrinkage rate S in the MD direction was determined by measuring the dimensions of the semi-aromatic polyamide film of the present invention after placing it in an atmosphere at 250°C for 5 minutes and then at 23°C and 50%RH for 2 hours. MD Thermal shrinkage rate S in the TD direction TD The values ​​are preferably -1.0% to 1.5%, more preferably -0.8% to 1.3%, and even more preferably -0.6% to 1.0%. When the thermal shrinkage rate of the semi-aromatic polyamide film in the MD and TD directions is less than 1.5%, it can suppress processing failures caused by dimensional changes under high-temperature processing conditions.

[0075] Furthermore, from the viewpoint of excellent visibility, the haze of the semi-aromatic polyamide film of the present invention, as measured according to JIS K7105, is preferably 14% or less, more preferably 12% or less, and even more preferably 10% or less. Additionally, for a semi-aromatic polyamide film with a thickness of 25 μm or less, the haze is preferably 7% or less, more preferably 6% or less, and even more preferably 5% or less.

[0076] [Manufacturing method of semi-aromatic polyamide film]

[0077] The semi-aromatic polyamide film of the present invention can be produced by simultaneously biaxially stretching an unstretched film, or by successively biaxially stretching an unstretched film in the MD direction and then stretching the resulting uniaxially stretched film in the MD direction in the TD direction.

[0078] The semi-aromatic polyamide film of the present invention is preferably manufactured by the following process [1] or [2].

[0079] [1] The process of preheating the unstretched semi-aromatic polyamide film, the process of stretching it simultaneously in the MD and TD directions, and the process of cooling it.

[0080] [2] The process of preheating the MD-direction uniaxially stretched film of semi-aromatic polyamide, the process of stretching it in the TD direction, and the process of cooling it.

[0081] In addition, a heat-fixing process and a relaxation process can be set between the stretching process and the cooling process.

[0082] Regarding the present invention, the fabrication of the membrane based on a successive biaxial stretching method is preferred. Compared with simultaneous biaxial stretching, the apparatus configuration of the successive biaxial stretching method is simpler, and equipment investment costs can be reduced. Furthermore, the stretching conditions in the MD and TD directions can be adjusted independently, allowing relaxation treatment to be performed separately in both directions. Therefore, the directionality of mechanical strength, etc., can be appropriately set according to the application.

[0083] The semi-aromatic polyamide used in this invention has very high crystallinity. Therefore, when using the successive biaxial stretching method, the following situation exists: firstly, orientation crystallization easily occurs during stretching in the MD direction, and then stretching along the TD direction becomes difficult.

[0084] On the other hand, when the thickness of the semi-aromatic polyamide film is greater than 50 μm, the force required to stretch the film in the simultaneous biaxial stretching method is too large, and sometimes stretching becomes difficult. In this case, the successive biaxial stretching method is preferred.

[0085] (Unstretched film of semi-aromatic polyamide)

[0086] Unstretched films of semi-aromatic polyamides can be manufactured by melt-blending and forming a film from a film raw material containing at least semi-aromatic polyamide using an extruder.

[0087] Commercially available products can be used as semi-aromatic polyamides. Examples of such commercially available products include "Genestar (registered trademark)" manufactured by Kuraray Co., Ltd., "XecoT (registered trademark)" manufactured by Uniqlo Co., Ltd., "Reny (registered trademark)" manufactured by Mitsubishi Engineering Plastics Co., Ltd., "Arlen (registered trademark)" manufactured by Mitsui Chemicals Co., Ltd., and "Ultramid (registered trademark)" manufactured by BASF.

[0088] Furthermore, semi-aromatic polyamides can be manufactured using methods known as methods for manufacturing crystalline polyamides. Examples include: solution polymerization or interfacial polymerization using acyl chlorides and diamines as raw materials (Method A); methods for producing oligomers from dicarboxylic acids and diamines, and then increasing the molecular weight of the oligomers by melt polymerization or solid-state polymerization (Method B); methods for producing a pulverized mixture of salt and oligomers from dicarboxylic acids and diamines as raw materials, and then performing solid-state polymerization on this mixture (Method C); and methods for producing a salt from dicarboxylic acids and diamines as raw materials, and then performing solid-state polymerization on this mixture (Method D), etc.

[0089] In method B, for example, nylon salt prepared by mixing diamine, dicarboxylic acid, and polymerization catalyst is heated and polymerized at a temperature of 200–250°C to obtain oligomers. The limiting viscosity of the oligomer is preferably 0.1–0.6 dL / g. By setting the limiting viscosity of the oligomer to a range of 0.1 dL / g or higher, it is advantageous to maintain the molar balance between the carboxyl groups of the dicarboxylic acid and the amino groups of the diamine while increasing the polymerization rate in subsequent solid-state polymerization and melt polymerization. Furthermore, by setting the limiting viscosity of the oligomer to a range of 0.6 dL / g or lower, coloration of the resulting semi-aromatic polyamide can be prevented.

[0090] Solid-state polymerization of oligomers is preferably carried out under reduced pressure or with a flow of inactive gas. Furthermore, the solid-state polymerization temperature is preferably 200–280°C. By setting the solid-state polymerization temperature within this range, the polymerization rate can be increased, and semi-aromatic polyamides can be rapidly generated. Additionally, coloring and gelation of the resulting semi-aromatic polyamides can be suppressed.

[0091] From the perspective of suppressing the decomposition and thermal degradation of semi-aromatic polyamides to obtain semi-aromatic polyamides with high strength and excellent appearance, the melt polymerization of oligomers is preferably carried out at a temperature below 350°C. It should be noted that the above-mentioned melt polymerization also includes melt polymerization using a melt extruder.

[0092] In method C, for example, a suspension containing a molten aliphatic diamine and a solid aromatic dicarboxylic acid is stirred and mixed to obtain a mixture. Then, in this mixture, a reaction based on the reaction of the aromatic dicarboxylic acid with the aliphatic diamine to form a salt, and a reaction based on the polymerization of the formed salt to form an oligomer, are carried out at a temperature lower than the melting point of the final semi-aromatic polyamide, to obtain a mixture of salt and oligomer. In this case, pulverization can be performed while reacting, or the mixture can be removed after the reaction and then pulverized. Subsequently, the resulting reactants are subjected to solid-state polymerization at a temperature lower than the melting point of the final semi-aromatic polyamide to increase its molecular weight to a specified molecular weight, thereby obtaining a semi-aromatic polyamide. Solid-state polymerization is preferably carried out at a polymerization temperature of 180–270°C, a reaction time of 0.5–10 hours, and in a stream of inert gas such as nitrogen.

[0093] In method D, for example, aromatic dicarboxylic acid powder is preheated to a temperature above the melting point of an aliphatic diamine but below the melting point of the aromatic dicarboxylic acid. To maintain the powder state of the aromatic dicarboxylic acid, an aliphatic diamine is added to the powder in a substantially anhydrous state to form a salt. Subsequently, the resulting salt is subjected to solid-state polymerization at a temperature lower than the melting point of the ultimately formed semi-aromatic polyamide to increase its molecular weight to a specified molecular weight, thereby obtaining a semi-aromatic polyamide. Solid-state polymerization is preferably carried out at a polymerization temperature of 180–270°C, a reaction time of 0.5–10 hours, and in a stream of inert gas such as nitrogen.

[0094] Regarding the present invention, methods C and D are preferred, with method D being more preferred. Compared to method B, methods C and D can generate a pulverized mixture of salt and oligomers, and the salt itself, at low temperatures. Furthermore, the generation of the pulverized mixture of salt and oligomers, and the salt, does not require a large amount of water. Therefore, the formation of gel-like substances can be reduced, and fisheye defects can be minimized.

[0095] As a semi-aromatic polyamide, it can be made from virgin raw materials, or it can be made from defective films and scrap materials generated during film manufacturing, which can be recycled and mixed with virgin raw materials. Common methods for mixing raw materials include dry mixing and melt mixing using a single-screw extruder or a twin-screw extruder to obtain the composite material.

[0096] In addition to semi-aromatic polyamides, the above-mentioned membrane raw materials may contain one or more additives as needed to further enhance their various properties. Examples of additives include lubricants, pigments (e.g., titanium), dyes and other colorants, anti-coloring agents, heat stabilizers, antioxidants (e.g., hindered phenols, phosphate esters, phosphites), weather resistance modifiers (e.g., benzotriazole compounds), flame retardants (e.g., brominated flame retardants, phosphorus flame retardants), plasticizers, release agents, reinforcing agents (e.g., talc), modifiers, antistatic agents, ultraviolet absorbers, antifogging agents, and various polymer resins.

[0097] Examples of lubricants include inorganic particles such as silica, alumina, titanium dioxide, calcium carbonate, kaolin, and barium sulfate; and organic particles such as acrylic resin particles, melamine resin particles, silicone resin particles, and cross-linked polystyrene particles. The average particle size of the lubricant is, for example, 0.05–5.0 μm. The lubricant content can be selected based on frictional characteristics, optical properties, and other required membrane properties, for example, 0.5% by mass or less, preferably 0.4% by mass or less, particularly preferably 0.3% by mass or less, and most preferably 0.2% by mass or less. Alternatively, the lubricant content is, for example, 0.05% by mass or more, preferably 0.1% by mass or more. Furthermore, by adding a lubricant to the membrane raw material, the haze of the resulting membrane can be suppressed.

[0098] Unstretched films containing semi-aromatic polyamides and the above-mentioned additives can be manufactured, for example, by the following methods.

[0099] (A) A method of adding additives during the polymerization of semi-aromatic polyamides to generate semi-aromatic polyamides containing additives, and then melting and forming the polyamides into films.

[0100] (B) A method of preparing granules by pre-melting high-concentration additives with semi-aromatic polyamides, and then melt-melting the masterbatch and natural granules (i.e., unadulterated semi-aromatic polyamide granules) with an extruder to form a film (masterbatch method).

[0101] (C) A method of feeding a dry mixture of semi-aromatic polyamide and additives into an extruder, and then using the extruder for melt mixing and film formation.

[0102] (D) A method of separately feeding semi-aromatic polyamide and additives into an extruder, and then using the extruder for melt mixing and film formation.

[0103] The heat of crystallization of the unstretched semi-aromatic polyamide film is preferably 20 J / g or more, more preferably 25 J / g or more. Furthermore, the aforementioned heat of crystallization is preferably 35 J / g or less, more preferably 30 J / g or less. When the heat of crystallization of the unstretched film is 20 J / g or more, stable stretching can be achieved using a small stretching force, thereby obtaining a stretched film with uniform thickness. Furthermore, the resulting film has a high elongation at break, and even when stress is applied externally in the TD direction, it can elongate following the stress, thereby suppressing breakage.

[0104] Unstretched films of semi-aromatic polyamide with a crystallization heat of 20 J / g or higher can be manufactured by melting and mixing semi-aromatic polyamide in an extruder at a temperature of 280–340°C for 3–15 minutes, then extruding it into sheets through a T-die, and then cooling the extruded sheets by pressing them together on a cooling roller with the temperature adjusted to 30–40°C.

[0105] In the method for manufacturing a semi-aromatic polyamide film according to the present invention, an unstretched semi-aromatic polyamide film is biaxially stretched. As a result, the semi-aromatic polyamide undergoes oriented crystallization.

[0106] (Uniaxial stretching process in the MD direction)

[0107] In the process of successively biaxially stretching an unstretched film, the unstretched film is stretched in the MD direction to obtain a uniaxially stretched film in the MD direction.

[0108] The stretch ratio in the MD direction is preferably 2.0 to 4.5 times. The lower limit of the above stretch ratio is preferably 2.3 times, more preferably 2.4 times. The upper limit of the above stretch ratio is preferably 3.5 times, more preferably 3.0 times, further preferably 2.8 times, particularly preferably 2.7 times, and most preferably 2.6 times.

[0109] When stretched at a stretching ratio of 4.5 times or less in the MD direction, crystallization occurs moderately, resulting in a uniaxially stretched film with excellent stretchability in the TD direction. Then, by stretching the obtained uniaxially stretched film in the MD direction along the TD direction, uneven stretching can be suppressed, yielding a biaxially stretched film with excellent thickness accuracy and transparency, and high elongation at break in the MD direction.

[0110] In addition, when the stretching ratio in the MD direction is 2.0 times or more, the generation of uneven stretching can be suppressed, and a stretch film with uniform thickness and high planarity can be obtained.

[0111] Regarding the stretching speed, the stretching deformation speed in the MD direction is preferably greater than 400% / min, more preferably 800 to 12000% / min, and even more preferably 1200 to 6000% / min. When stretching is performed at a stretching deformation speed greater than 400% / min, it is possible to prevent the film from breaking during stretching due to crystal growth. In addition, when stretching is performed at a stretching deformation speed of 12000% / min or less, the film can deform in accordance with the applied stress, which can prevent the film from breaking.

[0112] From the viewpoint of suppressing film breakage and producing biaxially stretched films with good yield, the stretching temperature, based on the glass transition temperature (Tg) of the semi-aromatic polyamide, is preferably (Tg-5) °C or higher, more preferably (Tg) °C or higher. Furthermore, from the viewpoint of suppressing uneven stretching, the stretching temperature is preferably (Tg+50) °C or lower, more preferably (Tg+45) °C or lower, and even more preferably (Tg+35) °C or lower.

[0113] For example, in the case of polyamide 9T film (Tg = 125°C for polyamide 9T), the stretching temperature is preferably 120–175°C, more preferably 120–170°C, and even more preferably 125–160°C.

[0114] (Preheating process)

[0115] The preheating process is a process of preheating the film (unstretched film in the case of simultaneous biaxial stretching, and uniaxially stretched film in the MD direction in the case of successive biaxial stretching) before the stretching process. From the viewpoint of suppressing relaxation, the preheating temperature T1 of the film is preferably in the range of (Tg-9)℃ to (Tg+5)℃ based on the glass transition temperature (Tg) of the semi-aromatic polyamide. The lower limit of the above preheating temperature T1 is preferably (Tg-6)℃, more preferably (Tg-5)℃. The upper limit of the above preheating temperature T1 is preferably (Tg+4)℃, more preferably (Tg+1)℃, further preferably (Tg)℃, and particularly preferably (Tg-1)℃.

[0116] When the preheating temperature of the membrane is less than (Tg-9)℃, the resulting membrane tends to have large relaxation at the ends. Conversely, when the preheating temperature of the membrane is greater than (Tg+5)℃, the resulting membrane tends to have large relaxation in the middle.

[0117] In the case where the preheating process involves changing the temperature in stages while preheating the film, the preheating temperature before the stretching process is preferably within the range described above.

[0118] For example, in the case of a polyamide 9T film (where Tg = 125°C), the preheating temperature T1 of the polyamide 9T film is preferably in the range of 116 to 130°C. The lower limit of the above preheating temperature T1 is preferably 119°C, more preferably 120°C. Furthermore, the upper limit of the above preheating temperature T1 is preferably 129°C, more preferably 126°C, even more preferably 125°C, and particularly preferably 124°C.

[0119] In this invention, relaxation can be suppressed by preheating the membrane within the aforementioned specific temperature range. While the principle behind suppressing relaxation by adjusting the membrane's preheating temperature is not yet fully understood, it is believed to be achieved by controlling warping phenomena.

[0120] When manufacturing films using a tenter frame stretching method, warping occurs due to stress generated on the film at the boundary between the stretching section and the heat-setting section. Specifically, when manufacturing stretched films using a tenter frame stretching method, the film passes through a preheating section, stretching section, heat-setting section, relaxation section, and cooling section. Near the end of the stretching section, i.e., at the position where the set stretch ratio is reached, the tensile stress reaches its maximum. At this time, inside the tenter frame, because the two ends of the film are held by clamps, the central portion of the film is pulled towards the end of the stretching section. Furthermore, the central portion of the film is pulled from the heat-setting section after the stretching section towards the stretching section. Therefore, the following warping phenomenon occurs: when the film exits the tenter frame in a straight line drawn perpendicular to its travel direction before entering the stretching machine, an arc is drawn in the direction opposite to the travel direction of the film's central portion. It is believed that this phenomenon causes a substantial difference in the stretch ratio of the film's travel direction between the central portion and the two ends, affecting the film's relaxation. Furthermore, it is speculated that by controlling the temperatures of the preheating and cooling sections within a specific range, the occurrence of warping can be suppressed, thereby suppressing relaxation.

[0121] (Stretching process)

[0122] The stretching process is a process of stretching a film to obtain a biaxially stretched film. Furthermore, when the film supplied to this process is an unstretched film, the process involves simultaneously biaxially stretching the unstretched film in both the MD and TD directions. When the film supplied to this process is a uniaxially stretched film in the MD direction, the process involves stretching the uniaxially stretched film in the MD direction in the TD direction.

[0123] When a uniaxially stretched film in the MD direction is stretched in the TD direction (in the case of successive biaxial stretching), the stretching ratio in the TD direction is preferably 2.0 to 5.0 times, more preferably 2.0 to 4.0 times, even more preferably 3.0 to 4.0 times, and particularly preferably 3.3 to 3.8 times.

[0124] When the stretching ratio in the TD direction is within the above range, it can suppress the generation of uneven stretching and obtain a biaxially stretched film with excellent thickness accuracy and transparency, and high tensile elongation at break in the TD direction.

[0125] When the unstretched film is simultaneously biaxially stretched, the stretch ratio in the MD direction is preferably 2.0 to 4.5 times, more preferably 2.0 to 3.5 times, even more preferably 2.5 to 3.5 times, and particularly preferably 2.5 to 3.3 times. Furthermore, the stretch ratio in the TD direction is preferably 2.0 to 5.0 times, more preferably 2.0 to 4.0 times, even more preferably 3.0 to 4.0 times, and particularly preferably 3.3 to 3.8 times.

[0126] When stretched in the MD direction at a stretch ratio of 4.5 or less, a stretched film with low heat shrinkage and excellent dimensional stability can be obtained. Furthermore, when stretched in the TD direction at a stretch ratio of 5.0 or less, a stretched film with low heat shrinkage, excellent dimensional stability, and consequently high elongation at break can be obtained.

[0127] In addition, when the stretching ratio in both the MD and TD directions is greater than 2.0, the generation of uneven stretching can be suppressed, and a stretch film with uniform thickness and high planarity can be obtained.

[0128] In the simultaneous biaxial stretching method, when obtaining a biaxially stretched film with a thickness of 1–25 μm, regarding the stretching ratio, a stretching ratio of 2.5–3.0 times in the MD direction is preferred, and a stretching ratio of 2.5–3.3 times in the TD direction is preferred. Furthermore, when obtaining a biaxially stretched film with a thickness of 26–50 μm, a stretching ratio of 2.8–3.3 times in the MD direction is preferred, and a stretching ratio of 3.0–3.5 times in the TD direction is preferred.

[0129] Regarding the stretching speed, it is preferable that the stretching deformation speed in both the MD and TD directions is greater than 400% / min, more preferably 800 to 12000% / min, and even more preferably 1200 to 6000% / min. When stretching is performed at a stretching deformation speed greater than 400% / min, it is possible to prevent the film from breaking during stretching due to crystal growth. In addition, when stretching is performed at a stretching deformation speed of 12000% / min or less, the film can deform in accordance with the applied stress, which can prevent the film from breaking.

[0130] From the viewpoint of suppressing film breakage and producing biaxially stretched films with good yield, the stretching temperature, based on the glass transition temperature (Tg) of the semi-aromatic polyamide, is preferably (Tg-5) °C or higher, more preferably (Tg) °C or higher. Furthermore, from the viewpoint of suppressing uneven stretching, the stretching temperature is preferably (Tg+50) °C or lower, more preferably (Tg+35) °C or lower, and even more preferably (Tg+30) °C or lower.

[0131] For example, in the case of polyamide 9T film (Tg = 125°C for polyamide 9T), the stretching temperature is preferably 120–160°C, more preferably 125–155°C. Furthermore, when the heating temperature of the stretching process is divided into two zones, the stretching temperature for the first half is preferably 120–140°C, more preferably 125–135°C. Additionally, the stretching temperature for the second half is preferably greater than 135°C and less than 160°C, more preferably 140–160°C, and particularly preferably 145–155°C.

[0132] (Heat setting process)

[0133] After the semi-aromatic polyamide film is stretched as described above, it is preferably subjected to a heat-setting treatment while the film is held in place by the clamps used during stretching. By performing a heat-setting treatment, the resulting film can reduce its thermal shrinkage rate without uneven heating. The heat-setting treatment temperature is preferably in the range of (Tm-30)℃ to (Tm)℃ based on the melting point (Tm) of the semi-aromatic polyamide, more preferably in the range of (Tm-27)℃ to (Tm-3)℃, and even more preferably in the range of (Tm-24)℃ to (Tm-6)℃. When the heat-setting treatment temperature is above (Tm-30)℃, a film with a low thermal shrinkage rate can be obtained. Furthermore, when the heat-setting treatment temperature is below (Tm)℃, defects such as heat-induced wrinkles and breakage during heat-setting can be suppressed, resulting in a biaxially stretched film with high elongation at break.

[0134] For example, in the case of polyamide 9T film (Tm of polyamide 9T = 290°C), the heat setting temperature is preferably 260-290°C, more preferably 263-287°C, and even more preferably 266-284°C.

[0135] Examples of heat-fixing methods include known methods such as blowing hot air, irradiating with infrared light, and irradiating with microwaves. Among these, the method of blowing hot air is preferred from the perspective of being able to perform uniform and high-precision heating.

[0136] (Relaxation process)

[0137] For the film after heat-fixing, it is preferable to perform relaxation treatment in the MD and TD directions at the same temperature as the heat-fixing treatment while holding it in a clamp.

[0138] The relaxation rate in the MD direction is, for example, 1.0% to 10.0%. The relaxation rate in the TD direction is, for example, 1.0% to 12.0%. When relaxation treatment is performed in the MD and TD directions with the above relaxation rates, it is possible to suppress relaxation and reduce thermal shrinkage, thereby obtaining a film with improved dimensional stability.

[0139] In the successive biaxial stretching method, when obtaining a biaxially stretched film with a thickness of 1 to 50 μm, the relaxation rate is preferably 1.0% to 6.0% in the MD direction and 1.0% to 12.0% in the TD direction. When obtaining a biaxially stretched film with a thickness of 51 to 150 μm, the relaxation rate is preferably 1.0% to 3.0% in the MD direction and 1.0% to 10.0% in the TD direction.

[0140] In the simultaneous biaxial stretching method, the relaxation rate is preferably 1.0% to 6.0% in the MD direction and 1.0% to 12.0% in the TD direction.

[0141] In the simultaneous biaxial stretching method, the relaxation process described above can be performed online simultaneously or separately in the MD and TD directions. When performed separately, this can be achieved by relaxing in the MD direction first, followed by relaxation in the TD direction, or by relaxing in the TD direction first, followed by relaxation in the MD direction.

[0142] On the other hand, in the successive biaxial stretching method, the relaxation treatment described above can be performed in the following ways: (i) after stretching in the MD direction and the TD direction, followed by thermosetting, the relaxation treatment can be performed simultaneously in the MD and TD directions online; or (ii) after stretching in the MD direction, the relaxation treatment can be performed in the MD direction, followed by stretching in the TD direction, followed by thermosetting, and then relaxation treatment in the TD direction. It should be noted that in (ii), if thermosetting is performed after stretching in the MD direction and relaxation in the MD direction, the resulting film becomes difficult to stretch in the TD direction. Therefore, performing thermosetting before stretching in the TD direction is not preferred. Furthermore, in the successive biaxial stretching methods described in (i) and (ii), stretching in the MD direction is performed first, followed by stretching in the TD direction. However, the successive biaxial stretching method can also be performed first in the TD direction, followed by stretching in the MD direction.

[0143] Alternatively, the relaxation process described above can be performed as follows: after biaxial stretching, relax the material online along the TD direction and temporarily wind it, then pass it offline under low tension in a drying oven set to a specified temperature, thereby performing relaxation in the MD direction.

[0144] (Cooling process)

[0145] The cooling process is the process of cooling the stretched film. The cooling temperature T2, based on the melting point (Tm) of the semi-aromatic polyamide, is preferably in the range of (Tm-260)℃ to (Tm-170)℃. From the viewpoint of suppressing relaxation, the lower limit of the cooling temperature T2 is preferably (Tm-245)℃, more preferably (Tm-240)℃, even more preferably (Tm-235)℃, further preferably (Tm-230)℃, particularly preferably (Tm-225)℃, and most preferably (Tm-220)℃. The upper limit of the cooling temperature T2 is preferably (Tm-180)℃, more preferably (Tm-185)℃, further preferably (Tm-190)℃, particularly preferably (Tm-195)℃, and most preferably (Tm-200)℃.

[0146] For example, in the case of a polyamide 9T film (Tm of polyamide 9T = 290°C), the cooling temperature T2 is, for example, 30–120°C. From the viewpoint of suppressing relaxation, the lower limit of the cooling temperature T2 is preferably 45°C, more preferably 50°C, even more preferably 55°C, further preferably 60°C, particularly preferably 65°C, and most preferably 70°C. The upper limit of the cooling temperature T2 is preferably 110°C, more preferably 105°C, further preferably 100°C, particularly preferably 95°C, and most preferably 90°C.

[0147] When manufacturing the semi-aromatic polyamide film of the present invention using the successive biaxial stretching method, from the viewpoint of adjusting the refractive index of the central part, left end and right end of the TD direction and the MD direction of the obtained film to a specific range, the preheating temperature T1 (°C) and the cooling temperature T2 (°C) preferably satisfy the following formula (4), more preferably satisfy the following formula (4-1), and even more preferably satisfy the following formula (4-2).

[0148] 1073≤10×T1-T2≤1211 (4)

[0149] 1085≤10×T1-T2≤1200 (4-1)

[0150] 1096≤10×T1-T2≤1188 (4-2)

[0151] The thickness of the semi-aromatic polyamide film of the present invention may be appropriately varied according to the application and purpose, preferably 1 to 150 μm, more preferably 10 to 100 μm, and even more preferably 20 to 80 μm.

[0152] The semi-aromatic polyamide film of the present invention can be manufactured using a flat film successive biaxial stretching method, a flat film simultaneous biaxial stretching method, a tubular method, etc. Examples of stretching devices for performing the flat film simultaneous biaxial stretching method include screw-type tenter frames, telescoping tenter frames, and linear motor-driven clamp tenter frames.

[0153] It should be noted that, regarding the apparatus for manufacturing the semi-aromatic polyamide film of the present invention, in order to prevent resin retention, it is preferable to perform a surface roughness reduction treatment on the surfaces of the cylinder, the melting section of the barrel, the metering section, the single tube, the filter, the T-die, etc. Examples of methods for reducing surface roughness include modifying the surface with a low-polarity substance, and depositing silicon nitride or diamond-like carbon onto the surface.

[0154] The resulting semi-aromatic polyamide film can be in the form of a single sheet or in the form of a film roll wound on a winding roller. In addition, the form of the film roll includes a raw material roll formed by winding a film obtained through preheating, stretching and cooling processes onto a winding roller, and a slit roll formed by cutting the raw material roll into the desired width.

[0155] Semi-aromatic polyamide films can be single-layer films or multi-layer structures composed of two or more layers.

[0156] In the case of a multilayer semi-aromatic polyamide film, a lubricant can be contained in at least one layer. For example, in a two-layer film, it is preferable that one layer contains a lubricant, and in a three-layer film, it is preferable that each of the layers located on both surfaces contains a lubricant. This makes it easy to control the surface roughness of the semi-aromatic polyamide film. It should be noted that the type and content of the lubricant can be appropriately adjusted according to the application.

[0157] To improve adhesion to other raw materials, the surface of the semi-aromatic polyamide film can be subjected to corona treatment, plasma treatment, acid treatment, flame treatment, etc.

[0158] Layers comprising metals, their oxides and other inorganic substances, other types of polymers, paper, woven fabrics, nonwoven fabrics, wood and the like may also be laminated onto the semi-aromatic polyamide film of the present invention.

[0159] <Uses>

[0160] The semi-aromatic polyamide film of this invention exhibits heat resistance and excellent dimensional stability under high-temperature conditions. Therefore, it can be used in various electronic materials, optical components, and other applications.

[0161] Specifically, the semi-aromatic polyamide film of the present invention can be used as packaging material for pharmaceuticals; packaging material for food such as cooked foods; packaging material for electronic components such as semiconductor packages; electrical insulation material for motors, transformers, cables, etc.; dielectric material for capacitors, etc.; magnetic tape material such as cassette tapes, digital data storage magnetic tapes, and videotapes; protective plates for solar cell substrates, liquid crystal panels, conductive films, display devices, etc.; electronic substrate material such as LED mounting substrates, flexible printed wiring substrates, and flexible flat cables; heat-resistant tapes such as cover films for flexible printed wiring, heat-resistant mask tapes, and industrial engineering tapes; heat-resistant barcode labels; heat-resistant reflective sheets; insulating tapes; various release films; heat-resistant base films; photographic films; molding materials; agricultural materials; medical materials; civil engineering and construction materials; and membranes for household and industrial use such as filter membranes.

[0162] Furthermore, the semi-aromatic polyamide film of the present invention exhibits excellent heat resistance, dimensional stability, and transparency, and therefore can be used in display materials and display devices in mobile devices, etc. Specifically, it can be used as a substrate film for various functional materials such as optical substrates, polarizers, and phase retardation plates in various displays such as liquid crystals and organic ELs, as well as a protective film and sealing film for light-emitting elements and display devices.

[0163] [Electronic Materials]

[0164] The electronic material of the present invention comprises at least the above-mentioned semi-aromatic polyamide film.

[0165] The aforementioned electronic materials include, for example, packaging materials for electronic components such as semiconductor packages; electrical insulation materials for motors, transformers, cables, etc.; dielectric materials for capacitor applications, etc.; magnetic tape materials such as cassette tapes, magnetic tapes for digital data storage, and videotapes; heat-resistant mask tapes, heat-resistant reflective sheets, insulating tapes, release films, etc.

[0166] [Optical Components]

[0167] The optical component of the present invention comprises at least the above-mentioned semi-aromatic polyamide film.

[0168] The aforementioned optical components include, for example, protective plates and protective films used in solar cell substrates, liquid crystal panels, conductive films, display devices, etc.; electronic substrate materials such as LED displays, OLED displays, LED mounting substrates, substrates for flexible printed wiring, and flexible flat cables; and protective films and sealing films for flexible printed wiring, such as cover films, insulating tapes, release films, polarizing plates, substrate films, light-emitting elements, and display devices.

[0169] The above description of the various components and combinations thereof of the present invention is just one example, and appropriate additions, omissions, substitutions, and modifications to the components can be made without departing from the spirit of the present invention. Furthermore, the present invention is not limited to specific embodiments.

[0170] Example

[0171] The present invention will now be described in detail through specific examples.

[0172] 1. Evaluation Methods

[0173] (1) Limiting viscosity of semi-aromatic polyamide

[0174] In concentrated sulfuric acid at 30°C, the intrinsic viscosity (η) of the resin at concentrations of 0.05, 0.1, 0.2, and 0.4 g / dL is calculated using the following formula. inh The value obtained by interpolating it to concentration 0 is used as the limiting viscosity [η].

[0175] ηinh = [ln(t1 / t0)] / c

[0176] (where η) inh t0 represents the intrinsic viscosity (dL / g), t1 represents the solvent flow time (seconds), t2 represents the resin solution flow time (seconds), and c represents the resin concentration in the solution (g / dL).

[0177] (2) Melting point Tm and glass transition temperature Tg of semi-aromatic polyamides

[0178] Using a differential scanning calorimeter (PerkinElmer DSC-7), the semi-aromatic polyamide was heated from 20°C to 350°C at a rate of 10°C / min under a nitrogen atmosphere and held for 5 minutes (first scan). It was then cooled from 350°C to 20°C at a rate of 100°C / min and held for 5 minutes. Subsequently, the temperature was raised again from 20°C to 350°C at a rate of 10°C / min. The glass transition temperature of this process (second scan) was set as the Tg of the semi-aromatic polyamide. Similarly, the peak temperature of the crystallization melting peak observed in the second scan was set as Tm.

[0179] (3) Heat of crystallization of unstretched film

[0180] Using a differential scanning calorimeter (PerkinElmer DSC-7), 10 mg of unstretched semi-aromatic polyamide sheet was heated from 40 °C to 350 °C at a rate of 20 °C / min under a nitrogen atmosphere (first scan), and the heat of the resulting calorific peak was determined.

[0181] (4) Thermal shrinkage rate of semi-aromatic polyamide film

[0182] Test pieces in the MD direction (100mm length in the MD direction × 10mm width in the TD direction) and TD direction (100mm length in the TD direction × 10mm width in the MD direction) were cut from a semi-aromatic polyamide film. The resulting test pieces were placed in an atmosphere of 250°C for 5 minutes, followed by a treatment at 23°C and 50%RH for 2 hours. The length direction dimensions were measured after the treatment, and the thermal shrinkage rate S of the test piece in the MD direction was calculated using the following formula. MD and the thermal shrinkage rate S of the test piece in the TD direction TD .

[0183] Heat shrinkage rate (%) = [{length before treatment - length after treatment} / length before treatment] × 100

[0184] (5) Refractive index of semi-aromatic polyamide film

[0185] One circumference of the surface layer was cut from the 400 mm diameter film roll obtained in the examples and comparative examples and used as a sample.

[0186] Using the method according to JIS K7142, the refractive index n in the MD direction of the obtained sample was determined at three locations along a line parallel to the TD direction using an Abbe refractometer DR-M2 (manufactured by Aitek Co., Ltd.). It should be noted that a sodium D-line was used as the light source, a test piece with a refractive index of 1.74 was used, and diiodomethane was used as the intermediate solution.

[0187] More specifically, the refractive index n in the MD direction of the central part of the sample C The refractive index n in the MD direction at a position 10% inside the sample width from the left end. L The refractive index n in the MD direction at a position 10% inside the sample width from the right end. R The measurements were taken.

[0188] Then, the refractive index difference n is calculated according to the following equation (1). D .

[0189] Refractive index difference n D ={(n C -n L ) - (n C -n R )} / twenty one)

[0190] In addition, the average refractive index n is obtained according to the following equation (2). Av .

[0191] Average refractive index n Av = (n C +n L +n R ) / 3 (2)

[0192] (6) Relaxation amount

[0193] Cut a circumference of the surface layer from a 400mm diameter membrane roll and use it as a sample. Release the tension from the roll and lay the sample flat on a plane. Measure the length in the MD direction from one end to the other along the TD direction, using a 50mm scale. The maximum length L is then used as the reference. max and minimum value L min The relaxation amount is obtained by the following formula (3) (see Figure 1 ).

[0194] Relaxation amount (‰) = (L) max -L min )÷L max ×1000 (3)

[0195] 2. Raw materials

[0196] (1) Semi-aromatic polyamide

[0197] The semi-aromatic polyamide A obtained in the manufacturing example 1 below is used.

[0198] Manufacturing Example 1 (Manufacturing of Semi-Aromatic Polyamide A)

[0199] 3289 parts by weight of terephthalic acid (TPA), 2533 parts by weight of 1,9-nonanediamine (NDA), 633 parts by weight of 2-methyl-1,8-octanediamine (MODA), 48.9 parts by weight of benzoic acid (BA), 6.5 parts by weight of sodium hypophosphite monohydrate (representing 0.1% by weight relative to the total of the four polyamide raw materials mentioned above), and 2200 parts by weight of distilled water were added to a reaction vessel for nitrogen replacement. The molar ratio of these raw materials (TPA / BA / NDA / MODA) was 99 / 2 / 80 / 20.

[0200] After stirring the contents of the reactor at 100°C for 30 minutes, the internal temperature was raised to 210°C over 2 hours. At this point, the internal pressure of the reactor was increased to 2.12 MPa. The reaction continued under this condition for 1 hour, then the temperature was raised to 230°C. For the next 2 hours, the temperature was maintained at 230°C while slowly discharging water vapor and maintaining the pressure at 2.12 MPa. Next, the pressure was reduced to 0.98 MPa over 30 minutes, and the reaction continued for another hour to obtain the prepolymer. After drying at 100°C under reduced pressure for 12 hours, it was pulverized to a size of less than 2 mm.

[0201] Next, the pulverized prepolymer was subjected to solid-state polymerization at 230°C and 13.3 Pa for 10 hours to obtain the polymer. The resulting polymer was fed into a twin-screw extruder, melt-mixed and extruded at a barrel temperature of 320°C, cooled, and cut to produce granular semi-aromatic polyamide A. The obtained semi-aromatic polyamide A had an limiting viscosity of 1.17 dL / g, a melting point (Tm) of 290°C, and a glass transition temperature (Tg) of 125°C.

[0202] (2) Silica masterbatch flakes of semi-aromatic polyamide A (MI)

[0203] The masterbatch (MI) obtained in Manufacturing Example 2 below was used.

[0204] Manufacturing Example 2 (Manufacturing of Masterbatch Chip (MI))

[0205] 98 parts by mass of the semi-aromatic polyamide A obtained in Manufacturing Example 1 and 2 parts by mass of silica (Sylysia 310P manufactured by FUJI SILYSIACHEMICAL Co., Ltd., with an average particle size of 2.7 μm) were melt-blended to produce a masterbatch chip (M1) containing 2% by mass of silica.

[0206] Example 1

[0207] A mixture is obtained by mixing semi-aromatic polyamide A, heat stabilizer, and masterbatch flakes (M1) in such a manner that, relative to 100 parts by weight of semi-aromatic polyamide A, heat stabilizer (Sumilizer GA-80 manufactured by Sumitomo Chemical Co., Ltd.) is 0.2 parts by weight and silica is 0.1 parts by weight.

[0208] The resulting mixture was fed into a 65mm single-screw extruder with the barrel temperature set to 295℃ (front section), 320℃ (middle section), and 320℃ (rear section) for melting. It was then extruded into a sheet using a T-die set to 320℃ and electrostatically bonded to a cooling roller set to a surface temperature of 40℃ for cooling, resulting in a substantially non-oriented unstretched sheet with a thickness of 230μm (heat of crystallization 27J / g).

[0209] Next, the resulting unstretched sheet is biaxially stretched using a flat film successive stretching machine.

[0210] First, using a heating roller and an infrared heater, the heating roller is set to 110°C. Then, while heating the space to 150°C using the infrared heater, the unstretched film is stretched in the MD direction at a stretch ratio of 2.5 times to obtain a uniaxially stretched film in the MD direction.

[0211] Subsequently, while holding both ends of the MD-direction uniaxially stretched film with clamps, it is continuously fed into the TD-direction stretching machine. Furthermore, the MD-direction uniaxially stretched film is preheated in the preheating section inside the TD-direction stretching machine at a preheating temperature (T1) of 123°C, and then stretched in the stretching section at a stretching temperature of 130°C and a stretching ratio of 3.4 times along the TD direction.

[0212] After stretching, the heat-fixing part is heat-fixed at 279°C.

[0213] Then, in the relaxation section, relaxation treatment is performed at the same temperature as the heat-fixed section, with a relaxation rate of 3% in the MD direction and a relaxation rate of 2.7% in the TD direction.

[0214] Then, the cooling section is cooled at a cooling temperature (T2) of 80°C.

[0215] Thus, a semi-aromatic polyamide membrane with a thickness of 27 μm was obtained. Furthermore, the obtained membrane was wound to obtain a membrane roll with a width of 1200 mm and a diameter of 400 mm.

[0216] Examples 2-8, Comparative Examples 1-5

[0217] Except for changes to the preheating temperature, stretching method, stretching ratio, relaxation rate, and cooling temperature as described in Table 1, the same procedure as in Example 1 was followed to obtain a semi-aromatic polyamide film and film roll.

[0218] [Table 1]

[0219]

[0220] As can be seen from Examples 1 to 7, when a process of preheating at a specified temperature before stretching and cooling at a specified temperature after stretching is performed, the refractive index difference n of the resulting semi-aromatic polyamide film can be reduced. D By adjusting the temperature to a specified range, a semi-aromatic polyamide film with excellent dimensional stability under high-temperature conditions and sufficiently small relaxation can be obtained. Furthermore, it is known that by controlling the cooling temperature after stretching to a more preferred range, a refractive index difference n can be obtained. D The semi-aromatic polyamide film, which is the most preferred range, can further reduce relaxation.

[0221] Furthermore, a comparison between Examples 1-7 and Example 8 shows that by adjusting the heat-fixing temperature, a semi-aromatic polyamide film with small relaxation amount and excellent dimensional stability under high temperature conditions can be obtained.

[0222] On the other hand, the semi-aromatic polyamide films obtained in Comparative Examples 1 to 5 have a refractive index difference n D The relaxation amount is large because it does not meet the range specified in this invention.

Claims

1. A semi-aromatic polyamide film, which is a rectangular semi-aromatic polyamide film having an edge along the MD direction and an edge along the TD direction. The refractive index difference n of the semi-aromatic polyamide film is calculated by the following formula (1). D The range is -0.0010 to 0.0045. Refractive index difference n D ={(n C -n L ) - (n C -n R )} / twenty one) In the formula, n C n is the refractive index along the MD direction at the central part of the film. L n is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film. R Let be the refractive index in the MD direction at a position 10% inside the film width from the right end of the film, where The central portion, left end portion, and right end portion are located on a line parallel to the TD direction of the membrane.

2. The semi-aromatic polyamide film according to claim 1, wherein, The average refractive index n of the semi-aromatic polyamide film is calculated by the following formula (2). Av The range is 1.5985 to 1.6045. Average refractive index n Av = (n C +n L +n R ) / 3 (2) In the formula, n C n L and n R Same as above.

3. The semi-aromatic polyamide film according to claim 1, wherein, The relaxation amount of the semi-aromatic polyamide film, as determined by the following method, is less than 3.0‰. <Methods for determining relaxation amount> From one end of the TD direction to the other, measure the length in the MD direction at 50mm intervals. Calculate the relaxation amount based on the maximum and minimum values ​​of this length using the following formula (3). Relaxation amount (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3).

4. The thermal shrinkage rate S in the MD direction of the semi-aromatic polyamide film according to claim 1, determined by measuring its dimensions after being placed at 250°C for 5 minutes and then at 23°C and 50%RH for 2 hours. MD and thermal shrinkage rate S in the TD direction TD The percentages are -1.0% to 1.5%.

5. A method for manufacturing a semi-aromatic polyamide film, wherein the semi-aromatic polyamide film according to any one of claims 1 to 4 is obtained by the following steps [1] or [2]: [1] The process of preheating the unstretched semi-aromatic polyamide film at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the glass transition temperature Tg of the semi-aromatic polyamide, the process of stretching it simultaneously in the MD direction and the TD direction, and the process of cooling it at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide; [2] The process of preheating the semi-aromatic polyamide uniaxially stretched film in the MD direction at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the Tg of the semi-aromatic polyamide, the process of stretching it in the TD direction, and the process of cooling it at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide.

6. An electronic material comprising the semi-aromatic polyamide film according to any one of claims 1 to 4.

7. An optical component comprising a semi-aromatic polyamide film according to any one of claims 1 to 4.

Images