Semiaromatic polyamide film and method for producing same

Abstract

Provided is a semi-aromatic polyamide film having a sufficiently small slack amount. The semi-aromatic polyamide film according to the present invention is a rectangular semi-aromatic polyamide film having sides in the MD direction and sides in the TD direction, wherein the refractive index difference nD, as calculated by formula (1), is-0.0010 to 0.0045. Refractive index difference nD = {(nC-nL)-(nC-nR)} / 2 (1) (In the formula, nC is the refractive index in the MD direction in the center portion of the film, nL is the refractive index in the MD direction at a position inside 10% of the film width from the left end portion of the film, and nR is the refractive index in the MD direction at a position inside 10% of the film width from the right end portion of the film).

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202580004549.4 (22) Application Date 2025.09.26 (30) Priority Data 2024-169734 2024.09.30 JP (85) PCT International Application Entering National Phase Date 2026.03.12 (86) PCT International Application Application Data PCT / JP2025 / 034012 2025.09.26 (87) PCT International Application Publication Data WO2026 / 071040 JA 2026.04.02 (71) Applicant Uniqlo Co., Ltd. Address Japan (72) Inventors Kato Makoto, Nakahara Junichi, Okabe Takashi (74) Patent Agency Zhongke Patent & Trademark Agency Co., Ltd. 11021 Patent Attorney Zhu Dan (51) Int.Cl. B29C 55 / 12 (2006.01) C08J 5 / 18 (2006.01) G02B 5 / 30 (2006.01) H10K 50 / 842 (2006.01) H10K 50 / 844 (2006.01) H10K 59 / 10 (2006.01) H10K 77 / 10 (2006.01) B29K 77 / 00 (2006.01) B29L 7 / 00 (2006.01) (54) Invention Title Semi-aromatic Polyamide Film and Method for Manufacturing Thereof (57) Abstract This invention provides a semi-aromatic polyamide film with sufficiently small relaxation amount. 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 the refractive index difference nD calculated by the following formula (1) is -0.0010 to 0.0045. Refractive index difference nD = {(nC - nL) - (nC - nR)} / 2 (1) (where nC is the refractive index in the MD direction of the central part of the film, nL is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film, and nR is the refractive index in the MD direction at a position 10% inside the film width from the right end of the film).Claims 1 page Description 17 pages Drawings 1 page CN 122138903 A 2026.06.02 CN 1 22 13 89 03 A 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, wherein the refractive index difference nD of the semi-aromatic polyamide film calculated by the following formula (1) is -0.0010 to 0.0045, Refractive index difference nD = {(nC - nL) - (nC - nR)} / 2 (1) Wherein, nC is the refractive index in the MD direction of the central part of the film, nL is the refractive index in the MD direction at a position 10% inside the width of the film from the left end of the film, and nR is the refractive index in the MD direction at a position 10% inside the width of the film from the right end of the film, wherein the central part, the left end and the right end are located on a line parallel to the TD direction of the film. 2. The semi-aromatic polyamide film according to claim 1, wherein the average refractive index nAv of the semi-aromatic polyamide film calculated by the following formula (2) is 1.5985 to 1.6045, the average refractive index nAv = (nC + nL + nR) / 3 (2) where nC, nL, and nR are the same as above. 3. The semi-aromatic polyamide film according to claim 1, wherein the relaxation amount of the semi-aromatic polyamide film measured by the following method is 3.0‰ or less, <Method for measuring relaxation amount> From one end of one side along the TD direction to the other end, the length in the MD direction is measured in 50mm increments, and the relaxation amount is calculated based on the maximum and minimum values ​​of the length by the following formula (3), relaxation amount (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3). 4. The semi-aromatic polyamide film according to claim 1, wherein the heat shrinkage rate SMD in the MD direction and the heat shrinkage rate STD in the TD direction are -1.0% to 1.5% after being placed in an atmosphere of 250°C for 5 minutes and then placed in an atmosphere of 23°C and 50%RH for 2 hours, are measured.5. A method for manufacturing a semi-aromatic polyamide film, wherein the semi-aromatic polyamide film of any one of claims 1 to 4 is obtained by the following steps [1] or [2]: [1] a step of preheating an 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, a step of simultaneously stretching in the MD direction and the TD direction, and a step of cooling at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide; [2] a step of preheating a uniaxially stretched semi-aromatic polyamide film in the MD direction at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the Tg of the semi-aromatic polyamide, a step of stretching in the TD direction, and a step of cooling 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 the semi-aromatic polyamide film according to any one of claims 1 to 4. Claims 1 / 1 page 2 CN 122138903 A Semi-aromatic Polyamide Film and Manufacturing Method Thereof Technical Field

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

[0002] Semi-aromatic polyamide films stretched in the MD direction (length direction) and TD direction (width direction) have excellent heat resistance and mechanical properties, and are therefore used in various fields. Among the semi-aromatic polyamides constituting the semi-aromatic polyamide film, polyamide 9T, which is composed of an aliphatic diamine with 9 carbon atoms and terephthalic acid, and polyamide 10T, which is composed of an aliphatic diamine with 10 carbon atoms and terephthalic acid, have excellent heat resistance and mechanical properties.

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

[0004] On the other hand, Patent Document 2 discloses a film containing 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 becomes smaller. However, the film disclosed in Patent Document 2 deforms when exposed to high temperatures.

[0005] Prior Art 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] Problems to be Solved by the Invention

[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 could not sufficiently reduce the relaxation amount.

[0011] In addition, in recent years, for optical films such as display components, there has been a requirement for dimensional stability that does not deform even when exposed to high temperatures during transportation, heat processing, etc.

[0012] The object of the present 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 amount 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-described semi-aromatic polyamide film.

[0016] Means for solving the problem

[0017] The inventors conducted in-depth research in order to solve the above-described problem and found that if an unstretched film or a uniaxially stretched film in the MD direction is preheated at a specific temperature and then stretched, and then cooled at a specific temperature after stretching, the refractive index in the MD direction of each portion of the central, left, and right ends of the TD direction of the obtained film can be adjusted to a specific range, and the relaxation amount can be sufficiently reduced. In addition, it was found that if an unstretched film or a uniaxially stretched film in the MD direction is preheated at a specific temperature as specified in the specification 1 / 17 page 3 CN 122138903 A, then stretched, then heat-fixed at a specific temperature after stretching, and then cooled at a specific temperature, the relaxation amount of the obtained film can be sufficiently reduced, and the dimensional stability under high temperature conditions can be improved.

[0018] The present invention is made 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 nD calculated by the following formula (1) is -0.0010 to 0.0045.

[0021] Refractive index difference nD = {(nC - nL) - (nC - nR)} / 2 (1)

[0022] (where nC is the refractive index in the MD direction of the central part of the film, nL is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film, and nR is the refractive index 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 above-mentioned central part, left end and right end 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, whose average refractive index nAv calculated by the following formula (2) is 1.5985 to 1.6045.

[0024] Average refractive index nAv = (nC + nL + nR) / 3 (2)

[0025] (wherein, nC, nL and nR are the same as above.)

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

[0027] <Method for measuring relaxation amount>

[0028] From one end to the other end along the TD direction, the length in the MD direction is measured in 50mm increments, and the relaxation amount is calculated by the following formula (3) based on the maximum and minimum values ​​of the above-mentioned length.

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

[0030] The present invention also provides the above-mentioned semi-aromatic polyamide film, the heat shrinkage rate SMD in the MD direction and the heat shrinkage rate STD in the TD direction are -1.0% to 1.5% respectively after the film is placed in an atmosphere of 250°C for 5 minutes and then placed in an atmosphere of 23°C and 50%RH for 2 hours.

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

[0032] [1] A process of preheating an 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, a process of simultaneously stretching the film in the MD direction and the TD direction, and a process of cooling the film at a temperature of (Tm-260)℃ to (Tm-170)℃ based on the melting point Tm of the semi-aromatic polyamide

[0033] [2] A process of preheating a uniaxially stretched semi-aromatic polyamide film in the MD direction at a temperature of (Tg-9)℃ to (Tg+5)℃ based on the Tg of the semi-aromatic polyamide, a process of stretching the film in the TD direction, and a process of cooling the film 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 an electronic material 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] Effects of the Invention

[0037] According to the present invention, it is possible to provide a semi-aromatic polyamide film with sufficiently small relaxation (or, with sufficiently small relaxation and excellent dimensional stability even at high temperatures of 250°C).

[0038] The semi-aromatic polyamide film of the present invention can be suitably used as a base film, cover film and other electronic manual material for flexible printed circuit boards, such as a substrate for display boards, and as a heat-resistant tape. Brief Description of the Drawings

[0039] FIG1 is a diagram illustrating the method for measuring the amount of relaxation by taking the case of end relaxation as an example. Detailed Description of the Embodiments

[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 that contains at least a semi-aromatic polyamide as a resin component.

[0042] <Semi-aromatic Polyamide>

[0043] The semi-aromatic polyamide contains a dicarboxylic acid component (in other words, a component derived from a monomer) and a diamine component (in other words, a component derived from a diamine) as monomer components (in other words, a component derived from a monomer). In addition, the dicarboxylic acid component includes at least an aromatic dicarboxylic acid component, and the diamine component includes at least an aliphatic diamine component.

[0044] The semi-aromatic polyamide may contain other components besides the dicarboxylic acid component and the diamine component. In order to obtain a membrane with excellent heat resistance and low water absorption, the total content of the dicarboxylic acid component and the diamine 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.

[0045] In addition, the semi-aromatic polyamide may contain other components besides the aromatic dicarboxylic acid component and the aliphatic diamine component. In order to obtain a film with excellent heat resistance and low water absorption, the total content of the aromatic dicarboxylic acid component and the aliphatic diamine 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.

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

[0047] Regarding the above-mentioned aromatic dicarboxylic acid, in order to have excellent heat resistance and low water absorption, it is preferable to contain 60 mol% or more of terephthalic acid, more preferably 70 mol% or more, and further preferably 85 mol% or more.

[0048] Examples of aromatic dicarboxylic acids other than terephthalic acid include isophthalic acid and naphthalic acid. In addition, naphthalenecarboxylic 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 aliphatic diamines described above preferably contain aliphatic diamines with 6 to 12 carbon atoms as the main component. The content of aliphatic diamines with 6 to 12 carbon atoms in the total aliphatic diamines 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 with 6 to 12 carbon atoms is 60 mol% or more, the resulting membrane can balance heat resistance and productivity. Aliphatic diamines with 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 is 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; 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 above-mentioned aliphatic diamines, among aliphatic diamines with 6 to 12 carbon atoms, it is more preferable to include 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 above-mentioned aliphatic diamines may also contain, for example, 1,4-butanediamine, 1,5-pentanediamine, and other (linear) aliphatic diamines with 6 or fewer carbon atoms.

[0054] Among the above-mentioned diamines that form diamine components, in addition to aliphatic diamines, other diamines may be contained within a range that does not impair the effects of the present invention. Other diamines include, for example, 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-heptylactam, n-octylactam, 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 to 350°C. When the Tm of the semi-aromatic polyamide is below 350°C, thermal decomposition during film formation can be effectively suppressed. Furthermore, when the Tm is above 270°C, a film 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 film production rate is excellent, and a film with excellent mechanical strength can be manufactured.

[0058] <Other Components>

[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 polyamides as resin components. From the viewpoint of improving heat resistance and transparency, the proportion of semi-aromatic polyamides in the total amount of resin 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.

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

[0061] <Semi-aromatic polyamide film>

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

[0063] Refractive index difference nD = {(nC - nL) - (nC - nR)} / 2 (1)

[0064] (where nC is the refractive index in the MD direction of the central part of the film, nL is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film, and nR is the refractive index 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 part, the left end and the right end are located on a line parallel to the TD direction of the film.) Instruction manual 4 / 17 pages 6 CN 122138903 A

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

[0066] Average refractive index nAv = (nC + nL + nR) / 3 (2)

[0067] (wherein, nC, nL, and nR are the same as above.)

[0068] Since the refractive index difference nD of the semi-aromatic polyamide film of the present invention is in the above range (preferably the refractive index difference nD and the average refractive index nAv are in the above range), relaxation can be suppressed, and the relaxation amount of the film can be 3.0‰ or less. Therefore, it is possible to suppress wrinkles that occur when the film is wound onto the winding roller, or to prevent defects caused by wrinkles when the film wound onto the roller is pulled out for secondary processing. 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 relaxation amount described above is measured by the following measurement method. It should be noted that in the present invention, when the position where relaxation occurs (i.e., the position where the length in the MD direction is the largest) is located within 80% from the center in the TD direction of the film, it is called "middle relaxation", and when it is located within 10% from both ends in the TD direction of the film, it is called "end relaxation".

[0070] <Method for measuring relaxation amount>

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

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

[0074] In addition, the semi-aromatic polyamide film of the present invention exhibits excellent dimensional stability under high temperature conditions.The thermal shrinkage rates SMD and STD in the MD direction, determined by measuring the dimensions of the semi-aromatic polyamide film of the present invention after placing it at 250°C for 5 minutes and then at 23°C and 50%RH for 2 hours, 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 rates in the MD and TD directions of the semi-aromatic polyamide film are 1.5% or less, processing failures due to dimensional changes during high-temperature processing can be suppressed.

[0075] Furthermore, from the viewpoint of excellent visibility, the haze of the semi-aromatic polyamide film of the present invention, measured according to JIS K7105, is preferably 14% or less, more preferably 12% or less, and even more preferably 10% or less. In addition, 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 manufactured 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 steps [1] or [2].

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

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

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

[0082] Regarding the present invention, it is preferable to manufacture a film based on a successive biaxial stretching method. Compared with the simultaneous biaxial stretching method, the apparatus of the successive biaxial stretching method is simple to construct and can suppress the cost of equipment investment. In addition, the stretching conditions in the MD and TD directions can be adjusted independently, and relaxation treatment can be performed separately in the MD and TD 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] The unstretched film of semi-aromatic polyamide can be manufactured by melt-blending a film raw material containing at least semi-aromatic polyamide using an extruder and then forming a film.

[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); a method for producing oligomers using dicarboxylic acids and diamines as raw materials, and then increasing the molecular weight of the oligomers by melt polymerization or solid-state polymerization (Method B); a method for solid-state polymerization of a pulverized mixture of salt and oligomers produced using dicarboxylic acids and diamines as raw materials (Method C); and a method for solid-state polymerization of a salt produced using dicarboxylic acids and diamines as raw materials (Method D), etc.

[0089] In Method B, for example, a nylon salt prepared by mixing diamines, dicarboxylic acids, and a 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 group of the dicarboxylic acid and the amino group 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, it is also possible to prevent coloring of the resulting semi-aromatic polyamide.

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

[0091] From the perspective of suppressing the decomposition and thermal degradation of the semi-aromatic polyamide and obtaining a semi-aromatic polyamide with high strength and excellent appearance, melt polymerization of the oligomer is preferably carried out at a temperature of 350°C or lower. 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, at a temperature lower than the melting point of the final semi-aromatic polyamide, a reaction based on the reaction of the aromatic dicarboxylic acid and 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 to obtain a mixture of salt and oligomer. In this case, the powder can be pulverized while reacting, or it can be removed and pulverized after the reaction. Subsequently, the obtained 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 to 270°C, a reaction time of 0.5 to 10 hours, and in an inert gas stream 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 and below the melting point of the aromatic dicarboxylic acid. At this temperature, in order to maintain the powder state of the aromatic dicarboxylic acid, an aliphatic diamine is added in a substantially anhydrous state to generate a salt. Subsequently, the resulting salt is subjected to solid-state polymerization at a temperature lower than the melting point of the ultimately generated semi-aromatic polyamide to increase its molecular weight to a predetermined 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 inactive 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 at low temperatures, and the salt itself does not require a large amount of water during the generation of the pulverized mixture of salt and oligomers. Therefore, the formation of gel-like substances can be reduced, and fish-eye defects can be reduced.

[0095] As a semi-aromatic polyamide, only virgin raw materials can be used, or defective films and cut scraps (edges) generated during film manufacturing can be recycled and mixed with virgin raw materials. Examples of mixing methods for the raw materials include known methods such as dry mixing and melt mixing using a single-screw extruder or a twin-screw extruder to obtain the composite material.

[0096] In addition to the semi-aromatic polyamide, the above-mentioned film raw materials may contain one or more additives as needed to further improve 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 to 5.0 μm. The content of the lubricant can be selected according to the frictional characteristics, optical characteristics, and other required characteristics of the film, for example, it is 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. In addition, the content of the lubricant is, for example, 0.05% by mass or more, preferably 0.1% by mass or more. Furthermore, by adding lubricant to the film raw material, the effect of suppressing the haze of the resulting film can be obtained.

[0098] The unstretched film containing semi-aromatic polyamide and the above-mentioned additives can be manufactured, for example, by the following method.

[0099] (A) Adding additives during the polymerization of semi-aromatic polyamide to generate semi-aromatic polyamide containing additives, and then melting and forming a film

[0100] (B) Preparing granules by melt mixing high concentrations of additives with semi-aromatic polyamide, and then melting and forming a film by extrudering masterbatch and natural granules (i.e., semi-aromatic polyamide granules without additives)

[0101] (C) Feeding a dry mixture of semi-aromatic polyamide and additives into an extruder, and then melting and forming a film by extrudering

[0102] (D) Feeding semi-aromatic polyamide and additives into an extruder respectively, and then melting and forming a film by extrudering

[0103] The heat of crystallization of the unstretched film of semi-aromatic polyamide is preferably 20 J / g or more, more preferably 25 J / g as stated on page 7 / 17 of the specification, 9 CN 122138903 A. 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 performed using a small stretching force, thereby obtaining a stretched film with uniform thickness. Moreover, 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] An unstretched film of semi-aromatic polyamide with a crystallization heat of 20 J / g or more can be manufactured by melting and mixing the semi-aromatic polyamide in an extruder at a temperature of 280-340°C for 3-15 minutes, then extruding it into a sheet through a T-die, and cooling the extruded sheet by pressing it against a cooling roller with the temperature adjusted to 30-40°C.

[0105] In the manufacturing method of the semi-aromatic polyamide film of the present invention, the unstretched film of the semi-aromatic polyamide is biaxially stretched. As a result, the semi-aromatic polyamide undergoes orientation crystallization.

[0106] (MD direction uniaxial stretching process)

[0107] In the process of performing successive biaxial stretching of the unstretched film, the unstretched film is stretched in the MD direction to obtain a MD direction uniaxially stretched film.

[0108] The stretching ratio in the MD direction is preferably 2.0 to 4.5 times. The lower limit of the above stretching ratio is preferably 2.3 times, and more preferably 2.4 times. The upper limit of the above stretching 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 stretching is performed in the MD direction at a stretching ratio of 4.5 times or less, crystallization is moderate, and a uniaxially stretched film in the MD direction with excellent stretchability in the TD direction can be obtained. Then, by stretching the obtained uniaxially stretched film in the MD direction along the TD direction, the generation of stretching unevenness can be suppressed, and a biaxially stretched film with excellent thickness accuracy and transparency and high elongation at break in the MD direction can be obtained.

[0110] In addition, when the stretching ratio in the MD direction is 2.0 times or more, the generation of stretching unevenness can be suppressed, and a stretched 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 further preferably 1200 to 6000% / min. When stretching is performed at a stretching deformation rate greater than 400% / min, film breakage during stretching due to crystal growth can be prevented. Furthermore, when stretching is performed at a stretching deformation rate of 12000% / min or less, the film can deform in accordance with the applied stress, preventing film breakage.

[0112] From the viewpoint of suppressing film breakage and producing biaxially stretched films with good yield, the stretching temperature is preferably (Tg-5)°C or higher, more preferably (Tg)°C or higher, based on the glass transition temperature (Tg) of the semi-aromatic polyamide. 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 a 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)°C to (Tg+5)°C, 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)°C, more preferably (Tg-5)°C. The upper limit of the 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 film is less than (Tg-9)℃, there is a tendency for the obtained film to have end relaxation with a large relaxation amount. In addition, when the preheating temperature of the film is greater than (Tg+5)℃, there is a tendency for the obtained film to have middle relaxation with a large relaxation amount.

[0117] In the case where the preheating process is a process of preheating the film while changing the temperature in stages, it is preferable that the preheating temperature before the stretching process is in the above range.

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

[0119] In this invention, by preheating the film within the above-mentioned specific temperature range, relaxation can be suppressed. Although the principle of suppressing relaxation by adjusting the preheating temperature of the film is not yet clear, it is believed to be suppressed by controlling the warping phenomenon.

[0120] When manufacturing a film using a tenter frame stretching method, warping occurs due to the stress generated in the film at the boundary between the stretching section and the heat-fixing section. That is, when manufacturing a stretched film using a tenter frame stretching method, the film passes through the preheating section, stretching section, heat-fixing section, relaxation section, and cooling section, and the tensile stress reaches its maximum near the end of the stretching section, i.e., at the position where the set stretching ratio is reached. At this time, inside the tenter frame, because the two ends of the film are held by clamps, the central part of the film is pulled towards the end of the stretching section.Furthermore, the central portion of the film is pulled from the heat-fixing section after the stretching section to the stretching section. Therefore, the following warping phenomenon occurs: when the straight line drawn perpendicular to the film's travel direction before entering the stretching machine exits the stretching machine, an arc protruding from the central portion of the film in the opposite direction to the film's travel direction is drawn. It is believed that due to this phenomenon, the actual stretch ratio of the film's travel direction becomes different at the central portion and both ends of the film, which affects the relaxation of the film. Furthermore, it is speculated that by controlling the temperature of the preheating section and the cooling section within a specific range, the occurrence of warping phenomenon 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 provided to this process is an unstretched film, it is a process of simultaneously biaxially stretching the unstretched film in the MD direction and the TD direction; when the film provided to this process is a uniaxially stretched film in the MD direction, it is a process of stretching the uniaxially stretched film in the MD direction in the TD direction.

[0123] When the 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, the generation of uneven stretching can be suppressed, and a biaxially stretched film with excellent thickness accuracy and transparency and high tensile elongation at break in the TD direction can be obtained.

[0125] When the unstretched film is simultaneously biaxially stretched, the stretching 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 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.

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

[0127] In addition, when the stretching ratio in both the MD and TD directions is 2.0 times or more, uneven stretching can be suppressed, and a stretched 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 to 25 μm, regarding the stretching ratio, the stretching ratio in the MD direction is preferably 2.5 to 3.0 times, and the stretching ratio in the TD direction is preferably 2.5 to 3.3 times. Furthermore, when obtaining a biaxially stretched film with a thickness of 26 to 50 μm, the stretching ratio in the MD direction is preferably 2.8 to 3.3 times, and the stretching ratio in the TD direction is preferably 3.0 to 3.5 times.

[0129] Regarding the stretching speed, the stretching deformation speed in both the MD and TD directions 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. Furthermore, when stretching is performed at a stretching deformation rate of 12000% / min or less, the film can deform in accordance with the applied stress, thus preventing the film from breaking.

[0130] From the viewpoint of suppressing film breakage and producing biaxially stretched films with good yield, the stretching temperature is preferably (Tg-5) °C or higher, more preferably (Tg) °C or higher, based on the glass transition temperature (Tg) of the semi-aromatic polyamide. In addition, from the viewpoint of suppressing the generation of 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 of polyamide 9T = 125 °C), the stretching temperature is preferably 120 to 160 °C, more preferably 125 to 155 °C. In addition, when the heating temperature of the stretching process is divided into two regions, the stretching temperature of the first half is preferably 120 to 140 °C, more preferably 125 to 135 °C. Furthermore, the stretching temperature of the latter 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 preferable to perform a heat-setting treatment while holding the film with the clamp used during stretching. By performing a heat-setting treatment, the obtained film can reduce the heat shrinkage rate without uneven heating. The heat-setting treatment temperature is preferably in the range of (Tm-30)°C to (Tm)°C based on the melting point (Tm) of the semi-aromatic polyamide, more preferably in the range of (Tm-27)°C to (Tm-3)°C, and even more preferably in the range of (Tm-24)°C to (Tm-6)°C. When the heat-setting treatment temperature is above (Tm-30)°C, a film with a low heat shrinkage rate can be obtained. In addition, when the heat-fixing temperature is below (Tm)℃, it can suppress appearance defects such as heat-induced wrinkles and breakage during heat-fixing, and can obtain biaxial stretch film with high tensile elongation at break.

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

[0135] As a heat-setting method, known methods such as blowing hot air, irradiating with infrared light, and irradiating with microwaves can be cited. Among these, the blowing hot air method is preferred from the perspective of being able to perform heating uniformly and with high precision.

[0136] (Relaxation process)

[0137] For the film after heat-setting, it is preferable to perform relaxation treatment in the MD direction and TD direction at the same temperature as the heat-setting temperature 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-mentioned relaxation rates, it is possible to suppress relaxation and reduce thermal shrinkage while 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. Specification 10 / 17 pages 12 CN 122138903 A

[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 above-mentioned relaxation treatment can be performed online in the MD and TD directions simultaneously or separately. When performed separately, the relaxation process can be carried out by relaxing in the MD direction followed by relaxing in the TD direction, or relaxing in the TD direction followed by relaxing in the MD direction.

[0142] On the other hand, in the successive biaxial stretching method, the above-mentioned relaxation process can be performed in the following ways: (i) stretching in the MD direction and stretching in the TD direction, performing thermosetting treatment, and then simultaneously performing the relaxation process in the MD direction online; or (ii) stretching in the MD direction followed by relaxation in the MD direction, then stretching in the TD direction, performing thermosetting treatment, and then relaxing in the TD direction. It should be noted that in (ii), if thermosetting treatment is performed after stretching in the MD direction and relaxing in the MD direction, the resulting film becomes difficult to stretch in the TD direction. Therefore, performing thermosetting treatment in the stage before stretching in the TD direction is not preferred.In addition, in the successive biaxial stretching methods described in (i) and (ii) above, stretching is performed first in the MD direction, 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 treatment described above can also be performed as follows: after biaxial stretching, relaxation treatment is performed online along the TD direction and the film is temporarily wound, and then the film is passed through a drying oven set to a specified temperature under low tension in an offline state, thereby performing relaxation treatment in the MD direction.

[0144] (Cooling process)

[0145] The cooling process is a process of cooling the stretched film. The cooling temperature T2 is preferably in the range of (Tm-260)℃ to (Tm-170)℃, based on the melting point (Tm) of the semi-aromatic polyamide. 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 polyamide 9T film (Tm of polyamide 9T = 290℃), the cooling temperature T2 is, for example, 30 to 120℃. From the viewpoint of suppressing relaxation, the lower limit of the cooling temperature T2 is preferably 45°C, more preferably 50°C, 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 portion, 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 is appropriately varied according to the use and purpose, preferably 1~150μm, more preferably 10~100μm, and even more preferably 20~80μm.

[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 apparatuses 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 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 obtained 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. Furthermore, 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 a desired width.

[0155] The semi-aromatic polyamide film can be a single-layer film or a multilayer structure consisting of two or more layers.

[0156] In the case of a multilayer semi-aromatic polyamide film, at least one layer may contain a lubricant. For example, in a two-layer film, it is preferable that one layer contains a lubricant; in a three-layer film, it is preferable that each layer 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 containing inorganic materials such as metals and their oxides, other types of polymers, paper, woven fabrics, non-woven fabrics, wood, etc., can also be laminated on the semi-aromatic polyamide film of the present invention.

[0159] <Applications>

[0160] The semi-aromatic polyamide film of the present invention has 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 food; 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, videotapes, etc.; protective plates for solar cell substrates, liquid crystal panels, conductive films, display devices, etc.; electronic substrate materials such as LED mounting substrates, flexible printed wiring substrates, flexible flat cables, etc.; 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 has excellent heat resistance, dimensional stability, and transparency, and therefore can be used in display materials, display devices, etc., 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 materials of the present invention at least include the above-mentioned semi-aromatic polyamide film.

[0165] The above-mentioned 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, data storage 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 components of the present invention at least include the above-mentioned semi-aromatic polyamide film.

[0168] The aforementioned optical components include, for example, protective plates and protective films for 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, insulating tapes, release films, polarizing plates, substrate films, light-emitting elements, and display devices.

[0169] The above descriptions of the various configurations and combinations thereof are examples, and appropriate additions, omissions, substitutions, and modifications to the configurations can be made without departing from the spirit of the invention. Furthermore, the invention is not limited to the embodiments.

[0170] Examples

[0171] Hereinafter, the invention will be specifically described by way of examples.

[0172] 1. Evaluation method

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

[0174] In concentrated sulfuric acid, at a temperature of 30°C, the intrinsic viscosity (ηinh) of the resin at each concentration of 0.05, 0.1, 0.2 and 0.4 g / dL is calculated according to the following formula, and the value obtained by interpolation to concentration 0 is taken as the limiting viscosity [η].

[0175] ηinh=[ln(t1 / t0)] / c

[0176] (where ηinh represents the intrinsic viscosity (dL / g), t0 represents the solvent flow time (seconds), t1 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 polyamide

[0178] Using a differential scanning calorimeter (PerkinElmer DSC-7), the semi-aromatic polyamide was heated from 20°C to 350°C at 10°C / min under a nitrogen atmosphere and held for 5 minutes (first scan). Then, it was cooled from 350°C to 20°C at 100°C / min and held for 5 minutes. Then, it was heated from 20°C to 350°C again at 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 20 °C / min under a nitrogen atmosphere (first scan), and the heat of the resulting heating peak was calculated.

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

[0182] Test pieces in the MD direction (100 mm in length in the MD direction × 10 mm in width in the TD direction) and test pieces in the TD direction (100 mm in length in the TD direction × 10 mm in width in the MD direction) were cut from the semi-aromatic polyamide film. For the obtained test pieces, after being placed in an atmosphere of 250°C for 5 minutes, they were treated by placing them at a temperature of 23°C and a humidity of 50%RH for 2 hours. The length direction dimension after treatment was measured, and the heat shrinkage rate SMD of the test piece in the MD direction and the heat shrinkage rate STD of the test piece in the TD direction were calculated according to the following formula.

[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 film roll with a diameter of 400 mm 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 at three positions on a line parallel to the TD direction of the obtained sample was determined using an Abbe refractometer DR-M2 (manufactured by Aite Corporation). 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 nC in the MD direction of the central part of the sample, the refractive index nL in the MD direction of the sample at a position 10% inside the sample width from the left end, and the refractive index nR in the MD direction of the sample at a position 10% inside the sample width from the right end were measured.

[0188] Then, the refractive index difference nD was calculated according to the following formula (1). Instruction manual 13 / 17 pages 15 CN 122138903 A

[0189] Refractive index difference nD={(nC-nL)-(nC-nR)} / 2 (1)

[0190] In addition, the average refractive index nAv is calculated according to the following formula (2).

[0191] Average refractive index nAv=(nC+nL+nR) / 3 (2)

[0192] (6) Relaxation amount

[0193] One circumference of the surface layer is cut from a film roll with a diameter of 400mm and used as a sample. The tension of the obtained sample during winding is released and it is laid flat on a plane. 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 according to the maximum value Lmax and the minimum value Lmin of the above length by the following formula (3) (see Figure 1).

[0194] Relaxation amount (‰) = (Lmax - Lmin) ÷ Lmax × 1000 (3)

[0195] 2. Raw materials

[0196] (1) Semi-aromatic polyamide

[0197] Semi-aromatic polyamide A obtained in Manufacturing Example 1 below was 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 (the total of the above four polyamide raw materials is 0.1% by weight), and 2200 parts by weight of distilled water were added to the reactor for nitrogen replacement. The molar ratio of these raw materials (TPA / BA / NDA / MODA) is 99 / 2 / 80 / 20.

[0200] After stirring the contents of the reactor at 100°C for 30 minutes, the internal temperature is raised to 210°C over 2 hours. At this time, the internal pressure of the reactor is increased to 2.12 MPa.The reaction continued for 1 hour under this condition, then the temperature was raised to 230°C, and for the next 2 hours, the temperature was maintained at 230°C while slowly releasing water vapor and maintaining a pressure of 2.12 MPa. Next, the pressure was reduced to 0.98 MPa over 30 minutes, and the reaction continued for another hour to obtain a 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 a temperature of 230°C and a pressure of 13.3 Pa for 10 hours to obtain a polymer. The obtained polymer was fed to a twin-screw extruder, melt-blended 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 sheet (MI) of semi-aromatic polyamide A

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

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

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

[0206] Example 1

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

[0208] The obtained mixture was fed into a 65mm single-screw extruder with the barrel temperature set to 295°C (front section), 320°C (middle section), and 320°C (rear section) for melting. The mixture was extruded into a sheet using a T-die set to 320°C and electrostatically bonded to a cooling roller set to a surface temperature of 40°C for cooling, resulting in a substantially non-oriented unstretched sheet with a thickness of 230μm (heat of crystallization 27J / g). Instruction manual, pages 14 / 17, 16 CN 122138903 A

[0209] Next, the obtained 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 an 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 was continuously fed into the TD-direction stretching machine. The MD-direction uniaxially stretched film was preheated in the preheating section inside the TD-direction stretching machine at a preheating temperature (T1) of 123°C, and 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, it was heat-fixed in the heat-fixing section at 279°C.

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

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

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

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

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

[0218] [Table 1] Specification 15 / 17 pages 17 CN 122138903 A

[0219]

[0220] As can be seen from Examples 1-7, when the process of preheating at a specified temperature before stretching and cooling at a specified temperature after stretching is performed, the refractive index difference nD of the obtained semi-aromatic polyamide film can be adjusted to a specified range, and a semi-aromatic polyamide film with excellent dimensional stability under high temperature conditions and sufficiently small relaxation amount can be obtained. Furthermore, as can be seen from page 16 / 17 of the specification, CN 122138903 A, by controlling the cooling temperature after stretching to a more preferred range, a semi-aromatic polyamide film with a refractive index difference nD within the most preferred range can be obtained, which can further reduce the relaxation amount.

[0221] In addition, according to the comparison between Examples 1 to 7 and Example 8, by adjusting the heat-fixing treatment 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 large relaxation amount because the refractive index difference nD does not meet the range specified in the present invention. Page 17 / 17 of the specification, CN 122138903 A, Figure 1, Figure 1 / 1 of the specification, CN 122138903 A.

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.

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