Semiaromatic polyamide film and method for producing same

Abstract

Provided is a semiaromatic polyamide film having a sufficiently small amount of slack.　This semiaromatic polyamide film is a rectangular semiaromatic polyamide film having sides along the MD direction and sides along the TD direction, and the refractive index difference nD calculated from formula (1) is -0.0010 to 0.0045.　Formula (1): Refractive index difference nD = {(nC - nL) - (nC - nR)} / 2 (In formula (1), nC is the refractive index in the MD direction in 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 edge of the film, and nR is the refractive index in the MD direction at a position 10% inside the film width from the right edge of the film.)

Description

Semi-aromatic polyamide film and method for producing the same

[0001] The present invention relates to a semi-aromatic polyamide film with suppressed sag, a method for producing the same, and electronic materials and optical components including the semi-aromatic polyamide film.

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

[0003] Patent Document 1 discloses a biaxially stretched film obtained by biaxially stretching an unstretched film made of a semi-aromatic polyamide resin and having a specific heat of crystallization. However, the film disclosed in Patent Document 1 has a large amount of sag, and wrinkles may occur during winding or meandering may occur during running.

[0004] On the other hand, Patent Document 2 discloses that the amount of sag can be controlled by the cooling rate of a film made of an aliphatic polyamide resin and heat-fixed after biaxial stretching, and the amount of sag decreases when the cooling rate is decreased. However, the film disclosed in Patent Document 2 may generate distortion under conditions exposed to high temperatures.

[0005] International Publication No. 2020 / 230806, Japanese Patent Application Laid-Open No. 2008-297415

[0006] [[ID=I8]] Then, when the present inventor applied the method described in Patent Document 2 in order to control the amount of sag of the semi-aromatic polyamide film disclosed in Patent Document 1, the amount of sag could not be made sufficiently small.

[0007] Furthermore, in recent years, optical films used in display components and other applications are required to possess dimensional stability that prevents distortion even under conditions of exposure to high temperatures, such as during transportation or heat processing.

[0008] The object of the present invention is to provide a semi-aromatic polyamide film with a sufficiently small amount of sagging.

[0009] Another object of the present invention is to provide a semi-aromatic polyamide film that exhibits sufficiently small sag and excellent dimensional stability under high-temperature conditions.

[0010] Another object of the present invention is to provide a method for producing a semi-aromatic polyamide film with a sufficiently small amount of sagging.

[0011] Another object of the present invention is to provide electronic materials and optical components comprising the semi-aromatic polyamide film.

[0012] The inventors, through diligent research to solve the above problems, have found that by preheating an unstretched film or a uniaxially oriented film in the MD direction at a specific temperature, then stretching it, and cooling it at a specific temperature after stretching, the refractive index in the MD direction at the central, left, and right ends of the resulting film in the TD direction can be adjusted to a specific range, and the amount of sag can be sufficiently reduced. Furthermore, the inventors have found that by preheating an unstretched film or a uniaxially oriented film in the MD direction at a specific temperature, then stretching it, heat-setting it at a specific temperature after stretching, and then cooling it at a specific temperature, the amount of sag in the resulting film can be sufficiently reduced, and the dimensional stability under high-temperature conditions can be improved.

[0013] This invention was completed based on the aforementioned findings.

[0014] In other words, the present invention relates to a rectangular semi-aromatic polyamide film having sides aligned along the MD direction and sides aligned along the TD direction, wherein the refractive index difference n is calculated from the following formula (1). Ｄ The present invention provides a semi-aromatic polyamide film having a coefficient of -0.0010 to 0.0045.

[0015] Refractive index difference n Ｄ = {(n Ｃ -nＬ ) - (n Ｃ - n Ｒ}) / 2 (1) (where n Ｃ is the refractive index in the MD direction at the central part of the film, n Ｌ is the refractive index in the MD direction at a position 10% inside the film width from the left end of the film, n Ｒ is the refractive index in the MD direction at a position 10% inside the film width from the right end of the film. Incidentally, the central part, the left end part, and the right end part are located on the same straight line parallel to the TD direction of the film) The present invention also provides the semi-aromatic polyamide film having a refractive index average value n Ａｖ calculated from the following formula (2) of 1.5985 to 1.6045.

[0016] Refractive index average value n Ａｖ = (n Ｃ + n Ｌ + n Ｒ ) / 3 (2) (where n Ｃ , n Ｌ , and n Ｒ are the same as those above) The present invention also provides the semi-aromatic polyamide film having a sag amount measured by the following measurement method of 3.0‰ or less. <Measurement method of sag amount> Measure the length in the MD direction at 50 mm intervals from one end to the other end of one side along the TD direction, and obtain the sag amount from the maximum value and the minimum value of the length by the following formula (3).

[0017] Sag amount (‰) = (Maximum value - Minimum value) ÷ Maximum value × 1000 (3) The present invention also provides the semi-aromatic polyamide film in which the heat shrinkage rate S ＭＤ in the MD direction and the heat shrinkage rate S ＴＤ in the TD direction, which are obtained by measuring the dimensions after leaving it in an atmosphere of 250°C for 5 minutes and then leaving it in an atmosphere of a temperature of 23°C and a humidity of 50% RH for 2 hours, are -1.0 to 1.5%, respectively.

[0018] The present invention also provides a method for producing a semi-aromatic polyamide film, comprising the steps of [1] or [2] below: [1] Preheating an unstretched semi-aromatic polyamide film at a temperature of (Tg-9)°C to (Tg+5)°C based on the glass transition temperature Tg of the semi-aromatic polyamide; stretching it simultaneously in the MD and TD directions; and cooling it at a temperature of (Tm-260)°C to (Tm-170)°C based on the melting point Tm of the semi-aromatic polyamide. [2] Preheating a uniaxially stretched semi-aromatic polyamide film in the MD direction at a temperature of (Tg-9)°C to (Tg+5)°C based on the Tg of the semi-aromatic polyamide; stretching it in the TD direction; and cooling it at a temperature of (Tm-260)°C to (Tm-170)°C based on the melting point Tm of the semi-aromatic polyamide. The present invention also provides an electronic material comprising the semi-aromatic polyamide film.

[0019] The present invention also provides an optical component comprising the semi-aromatic polyamide film.

[0020] According to the present invention, it is possible to provide a semi-aromatic polyamide film that has a sufficiently small amount of sag (or has a sufficiently small amount of sag and exhibits excellent dimensional stability even under high temperature conditions of 250°C).

[0021] The semi-aromatic polyamide film of the present invention can be suitably used as an electronic material such as a base film or coverlay film for flexible printed circuit boards; an optical material such as a substrate for displays; and a heat-resistant tape.

[0022] Figure 1 illustrates a method for measuring the amount of sag, using the case of edge sag as an example.

[0023] [Semi-aromatic polyamide film] The semi-aromatic polyamide film of the present invention is a rectangular semi-aromatic polyamide film having sides aligned with the MD direction and sides aligned with the TD direction, and is a film containing at least a semi-aromatic polyamide as a resin component. <Semi-aromatic polyamide> 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, monomer-derived components). Furthermore, the dicarboxylic acid component contains at least an aromatic dicarboxylic acid component, and the diamine component contains at least an aliphatic diamine component.

[0024] Semi-aromatic polyamides may contain other components besides dicarboxylic acid and diamine components, but in order to obtain films with excellent heat resistance and low water absorption, the total content of dicarboxylic acid and diamine components is preferably, for example, 50% by mass or more of all components constituting the semi-aromatic polyamide, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0025] Furthermore, while 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, for example, 50% by mass or more of the total components constituting the semi-aromatic polyamide, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0026] The dicarboxylic acid forming the dicarboxylic acid component includes at least an aromatic dicarboxylic acid, and the diamine forming the diamine component includes at least an aliphatic diamine.

[0027] The aromatic dicarboxylic acid preferably contains 60 mol% or more of terephthalic acid, more preferably 70 mol% or more, and even more preferably 85 mol% or more, in terms of excellent heat resistance and low water absorption.

[0028] Examples of aromatic dicarboxylic acids other than terephthalic acid include isophthalic acid and naphthalenedicarboxylic acid. Furthermore, naphthalenedicarboxylic acid includes the 1,2-isomer, 1,3-isomer, 1,4-isomer, 1,5-isomer, 1,6-isomer, 1,7-isomer, 1,8-isomer, 2,3-isomer, 2,6-isomer, and 2,7-isomer.

[0029] In addition to aromatic dicarboxylic acids, other dicarboxylic acids may be included in the present invention, as long as they do not impair 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, dodecanediic acid, tetradecanediic acid, and octadecanediic acid.

[0030] The aliphatic diamine preferably contains aliphatic diamines having 6 to 12 carbon atoms as its main component. The content of aliphatic diamines having 6 to 12 carbon atoms in the total amount of 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 having 6 to 12 carbon atoms is 60 mol% or more, the resulting film can achieve both heat resistance and productivity. One type of aliphatic diamine having 6 to 12 carbon atoms may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the above content refers to their total content.

[0031] Examples of aliphatic diamines having 6 to 12 carbon atoms include linear 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 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.

[0032] The aliphatic diamine is more preferably composed mainly of aliphatic diamines having 9 to 12 carbon atoms, and even more preferably of polyamide 9T containing aliphatic diamine with 9 carbon atoms as the main component, or polyamide 10T containing aliphatic diamine with 10 carbon atoms as the main component.

[0033] The aliphatic diamine may include not only aliphatic diamines having 6 to 12 carbon atoms, but also (linear) aliphatic diamines having 6 or fewer carbon atoms, such as 1,4-butanediamine and 1,5-pentanediamine.

[0034] The diamine forming the diamine component may contain other diamines besides aliphatic diamines, as long as the effects of the present invention are not impaired. Examples of other diamines include alicyclic diamines such as isophorone diamine, norbornane dimethylamine, and tricyclodecane dimethylamine; and aromatic diamines such as metaxylylenediamine, paraxylylenediamine, metaphenylenediamine, and paraphenylenediamine.

[0035] The semi-aromatic polyamide may contain lactam components (in other words, lactam-derived components) such as ε-caprolactam, ζ-enanthractam, η-capryllactam, and ω-laurolactam as monomer components, to the extent that it does not impair the effects of the present invention.

[0036] The types of monomer components and copolymerization ratios constituting the semi-aromatic polyamide are preferably selected so that the melting point (Tm) of the resulting semi-aromatic polyamide is in the range of 270 to 350°C. A Tm of 350°C or lower allows for efficient suppression of thermal decomposition during film processing. Furthermore, a Tm of 270°C or higher enables the formation of a film with excellent heat resistance.

[0037] The intrinsic viscosity of the semi-aromatic polyamide is preferably 0.8 to 2.0 dL / g, and more preferably 0.9 to 1.8 dL / g. When the intrinsic viscosity of the semi-aromatic polyamide is 0.8 dL / g or higher, it is possible to produce a film with excellent film productivity and mechanical strength.

[0038] <Other Components> 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 contain resins other than semi-aromatic polyamide as a resin component, but from the viewpoint of improving heat resistance and transparency, the proportion of semi-aromatic polyamide 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, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more.

[0039] Furthermore, the semi-aromatic polyamide film of the present invention may contain other components as needed, in addition to the resin component. Examples of other components include polymerization catalysts (such as phosphoric acid, phosphorous acid, hypophosphorous acid, or salts thereof), end encapsulants (such as acetic acid, lauric acid, benzoic acid, octylamine, cyclohexylamine, aniline, etc.), and additives described later. <Semi-aromatic polyamide film> The semi-aromatic polyamide film of the present invention has a refractive index difference n calculated from the following formula (1). Ｄ The refractive index difference n is -0.0010 to 0.0045. Ｄ From the viewpoint of suppressing the occurrence of sagging, a value of -0.0005 to 0.0040 is preferred, 0.0000 to 0.0035 is more preferred, and 0.0010 to 0.0029 is most preferred.

[0040] Refractive index difference n Ｄ = {(n Ｃ -n Ｌ ) - (n Ｃ -n Ｒ )} / 2 (1) (where n Ｃ is the refractive index in the MD direction at the center of the film, n Ｌ n is the refractive index in the MD direction at a position 10% inward from the left edge of the film, n Ｒ n is the refractive index in the MD direction at a position 10% inward from the right edge of the film. (Note that the central part, left edge, and right edge are located on a line parallel to the TD direction of the film.) Furthermore, the semi-aromatic polyamide film of the present invention has an average refractive index n calculated from the following formula (2) from the viewpoint of suppressing the occurrence of sagging. Ａｖ The ratio is preferably 1.5985 to 1.6045, more preferably 1.5989 to 1.6040, and particularly preferably 1.5993 to 1.6036.

[0041] Average refractive index n Ａｖ = (n Ｃ +n Ｌ +n Ｒ ) / 3 (2) (where n Ｃ , n Ｌ , and n Ｒ (The same applies as above) The semi-aromatic polyamide film of the present invention has a refractive index difference n Ｄ Since the above range (preferably, refractive index difference n) Ｄ and average refractive index n Ａｖ Because the above range is used, the occurrence of sagging can be suppressed, and the amount of sagging in the film can be reduced to 3.0‰ or less. This makes it possible to suppress wrinkles when winding the film onto a winding roll, and to prevent problems caused by wrinkles when pulling out the film wound onto the roll for secondary processing. The amount of sagging in 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, even more preferably 1.5‰ or less, and most preferably 1.0‰ or less.

[0042] The amount of slack is measured by the following measurement method. In this invention, if the position where slack occurs (i.e., the position where the length in the MD direction is maximum) is within 80% of the center in the TD direction of the film, it is called "center slack," and if it is within 10% of both ends in the TD direction of the film, it is called "end slack." <Method for measuring the amount of slack> If the semi-aromatic polyamide film is in the form of a film roll formed by winding the film, cut out one circumference of the surface layer from a film roll with an outer diameter of 300 mm or more and use this as a sample. Measure the length in the MD direction at 50 mm intervals from one end to the other along one side of the obtained sample in the TD direction, and calculate the amount of slack from the maximum and minimum values ​​of the length using the following formula (3).

[0043] Furthermore, if the semi-aromatic polyamide film is in the form of a single sheet, the length in the MD direction is measured at 50 mm intervals from one end to the other of one side along the TD direction, and the amount of slack is calculated from the maximum and minimum values ​​of the said length using the following formula (3).

[0044] Slack amount (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3) 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 is determined by measuring the dimensions of the semi-aromatic polyamide film of the present invention after leaving it in a 250°C atmosphere for 5 minutes, and then leaving it at a temperature of 23°C and a humidity of 50% RH for 2 hours. ＭＤ and the thermal shrinkage coefficient S in the TD direction ＴＤ The thermal shrinkage rates of each 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 of the semi-aromatic polyamide film in the MD and TD directions are 1.5% or less, it is possible to suppress processing problems caused by dimensional changes when subjected to high-temperature processing.

[0045] Furthermore, from the viewpoint of excellent visibility, the semi-aromatic polyamide film of the present invention preferably has a haze of 14% or less, more preferably 12% or less, and even more preferably 10% or less, as measured in accordance with JIS K7105. Moreover, for semi-aromatic polyamide films 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.

[0046] [Method for producing semi-aromatic polyamide film] The semi-aromatic polyamide film of the present invention can be produced by a method of simultaneously biaxial stretching an unstretched film, or by a method of sequential biaxial stretching in which an unstretched film is first stretched in the MD direction, and the resulting uniaxially stretched film in the MD direction is stretched in the TD direction.

[0047] The semi-aromatic polyamide film of the present invention is preferably manufactured by following the steps of [1] or [2] below: [1] Preheating an unstretched semi-aromatic polyamide film, stretching it simultaneously in the MD and TD directions, and cooling it. [2] Preheating a uniaxially stretched semi-aromatic polyamide film in the MD direction, stretching it in the TD direction, and cooling it. Alternatively, a heat-setting step or a relaxation step may be provided between the stretching step and the cooling step.

[0048] In this invention, the manufacturing of film by a sequential biaxial stretching method is preferred. Compared to a simultaneous biaxial stretching method, the sequential biaxial stretching method has a simpler equipment configuration and can reduce the cost of capital investment. Furthermore, the stretching conditions in the MD and TD directions can be adjusted independently, and relaxation treatment can be applied in both the MD and TD directions. Therefore, directional properties such as mechanical strength can be appropriately set for each application.

[0049] The semi-aromatic polyamide used in this invention is highly crystalline. Therefore, when employing a sequential biaxial stretching method, orientation crystallization is likely to occur during the initial stretching in the MD direction, which can make subsequent stretching in the TD direction difficult.

[0050] On the other hand, when the thickness of the semi-aromatic polyamide film exceeds 50 μm, the force required to stretch the film becomes too strong in the simultaneous biaxial stretching method, making stretching difficult. In such cases, it is preferable to employ the sequential biaxial stretching method.

[0051] (Undrawn film of semi-aromatic polyamide) An undrawn film of semi-aromatic polyamide can be produced by melt-kneading a film raw material containing at least semi-aromatic polyamide in an extruder to form a film.

[0052] Commercially available products can be used as semi-aromatic polyamides. Examples of such commercially available products include "Genesta®" manufactured by Kuraray Co., Ltd., "Zecotto®" manufactured by Unitika Ltd., "Lenny®" manufactured by Mitsubishi Engineering Plastics Corporation, "Arlen®" manufactured by Mitsui Chemicals, Inc., and "Ultramid®" manufactured by BASF.

[0053] Furthermore, semi-aromatic polyamides can be produced using methods known for producing crystalline polyamides. Examples include solution polymerization or interfacial polymerization using acid chloride and diamine as raw materials (Method A), a method of producing a low polymer using dicarboxylic acid and diamine as raw materials and increasing the molecular weight of the low polymer by melt polymerization or solid-phase polymerization (Method B), a method of producing a salt and a crushed mixture of the low polymer using dicarboxylic acid and diamine as raw materials and solid-phase polymerization of this mixture (Method C), and a method of producing a salt using dicarboxylic acid and diamine as raw materials and solid-phase polymerization of this mixture (Method D).

[0054] In method B, for example, a nylon salt prepared by mixing a diamine, a dicarboxylic acid, and a polymerization catalyst can be heated and polymerized at a temperature of 200 to 250°C to obtain a low polymer. The intrinsic viscosity of the low polymer is preferably 0.1 to 0.6 dL / g. Setting the intrinsic viscosity of the low polymer to a range of 0.1 dL / g or higher has the advantage of accelerating the polymerization rate while maintaining the molar balance between the carboxyl groups of the dicarboxylic acid and the amino groups of the diamine during subsequent solid-phase polymerization or melt polymerization. Furthermore, setting the intrinsic viscosity of the low polymer to a range of 0.6 dL / g or lower can prevent the resulting semi-aromatic polyamide from becoming discolored.

[0055] Solid-phase polymerization of low polymers is preferably carried out under reduced pressure or under inert gas flow. The solid-phase polymerization temperature is preferably 200 to 280°C. By setting the solid-phase polymerization temperature within this range, the polymerization reaction rate can be increased, allowing for the rapid production of semi-aromatic polyamides. Furthermore, discoloration and gelation of the resulting semi-aromatic polyamides can be suppressed.

[0056] The melt polymerization of low polymers is preferably carried out at a temperature of 350°C or lower, as this suppresses the decomposition and thermal degradation of the semi-aromatic polyamide, resulting in a semi-aromatic polyamide with high strength and excellent appearance. The above-mentioned melt polymerization also includes melt polymerization using a melt extruder.

[0057] In method C, for example, a suspension consisting of 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 below the melting point of the final semi-aromatic polyamide, a reaction to produce a salt by the reaction of the aromatic dicarboxylic acid and aliphatic diamine, and a reaction to produce a low polymer by polymerization of the produced salt are carried out to obtain a mixture of salt and low polymer. In this case, crushing may be carried out while the reaction is in progress, or crushing may be carried out after the reaction has been completed and the mixture has been removed. The resulting reaction product is then subjected to solid-phase polymerization at a temperature below the melting point of the final semi-aromatic polyamide to increase its molecular weight to a predetermined molecular weight and obtain a semi-aromatic polyamide. Solid-phase polymerization is preferably carried out in an inert gas stream such as nitrogen at a polymerization temperature of 180 to 270°C and a reaction time of 0.5 to 10 hours.

[0058] In method D, for example, aromatic dicarboxylic acid powder is heated to a temperature above the melting point of the aliphatic diamine and below the melting point of the aromatic dicarboxylic acid. An aliphatic diamine is then added to the aromatic dicarboxylic acid powder at this temperature, without substantially containing water, in order to maintain the powder state of the aromatic dicarboxylic acid, to produce a salt. The resulting salt is then solid-phase polymerized at a temperature below the melting point of the final semi-aromatic polyamide to increase its molecular weight to a predetermined level, thereby obtaining a semi-aromatic polyamide. Solid-phase polymerization is preferably carried out in an inert gas stream such as nitrogen at a polymerization temperature of 180 to 270°C for a reaction time of 0.5 to 10 hours.

[0059] In this invention, methods C and D are preferred, with method D being more preferred. Compared to method B, methods C and D can produce the crushed mixture of salt and low polymer, and the salt, at low temperatures, and do not require a large amount of water during the production of the crushed mixture of salt and low polymer, or the salt. Therefore, the generation of gel-like material can be reduced, and fish eyes can be reduced.

[0060] As the semi-aromatic polyamide, only virgin raw materials may be used, or off-spec film and cut-off trim (edge ​​trim) produced as by-products during film manufacturing may be recovered and mixed with the virgin raw materials. Examples of methods for mixing the raw materials include known methods such as the dry blending method and the melt mixing method, which uses a single-screw or twin-screw extruder to obtain the compound.

[0061] In addition to the semi-aromatic polyamide, the aforementioned film raw material may contain one or more additives as needed to further improve its properties. Examples of additives include lubricants, colorants such as pigments (e.g., titanium) and dyes, color inhibitors, heat stabilizers, antioxidants (e.g., hindered phenols, phosphate esters, phosphite esters), weather resistance modifiers (e.g., benzotriazole compounds), flame retardants (e.g., brominated flame retardants, phosphorus-based flame retardants), plasticizers, mold release agents, reinforcing agents (e.g., talc), modifiers, antistatic agents, ultraviolet absorbers, antifogging agents, and various polymer resins.

[0062] Examples of lubricants include inorganic particles such as silica, alumina, titanium dioxide, calcium carbonate, kaolin, and barium sulfate; and organic fine 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 lubricant content can be selected according to the required properties of the film, such as friction characteristics, optical characteristics, and other properties, and is, 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 can be, for example, 0.05% by mass or more, preferably 0.1% by mass or more. Furthermore, adding a lubricant to the film raw material can suppress haze in the resulting film.

[0063] An unstretched film containing a semi-aromatic polyamide and the above-mentioned additive can be produced by, for example, the following methods: (A) Adding the additive during polymerization of the semi-aromatic polyamide to produce a semi-aromatic polyamide containing the additive, melting it, and forming a film; (B) Preparing pellets by melt-kneading a high concentration of the additive and the semi-aromatic polyamide, and then melt-kneading the masterbatch and natural pellets (i.e., additive-free semi-aromatic polyamide pellets) in an extruder to form a film (masterbatch method); (C) Feeding a dry blend of the semi-aromatic polyamide and the additive into an extruder, melt-kneading it in the extruder, and forming a film; (D) Feeding the semi-aromatic polyamide and the additive separately into an extruder, melt-kneading them in the extruder, and forming a film. The unstretched film of the semi-aromatic polyamide preferably has a crystallization heat of 20 J / g or more, and more preferably 25 J / g or more. Furthermore, the crystallization heat is preferably 35 J / g or less, and more preferably 30 J / g or less. If the crystallization heat of the unstretched film is 20 J / g or more, it can be stably stretched with a small stretching force, thus obtaining a stretched film with uniform thickness. Furthermore, the resulting film has a high tensile elongation at break, and even when stress is applied from the outside in the TD direction, it stretches in response to the stress, thus suppressing breakage.

[0064] An unstretched film of semi-aromatic polyamide having 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 to 340°C for 3 to 15 minutes, extruding it into a sheet through a T-die, and then cooling the extruded sheet by bringing it into close contact with a cooling roll whose temperature is controlled to 30 to 40°C.

[0065] In the method for producing a semi-aromatic polyamide film of the present invention, the unstretched semi-aromatic polyamide film is biaxially stretched. This causes the semi-aromatic polyamide to undergo oriented crystallization. (Uniaxial stretching in the MD direction) In the process of sequentially biaxially stretching the unstretched film, this is a step in which the unstretched film is stretched in the MD direction to obtain a uniaxially stretched film in the MD direction.

[0066] The stretching ratio in the MD direction is preferably 2.0 to 4.5 times. The lower limit of the stretching ratio is preferably 2.3 times, more preferably 2.4 times. The upper limit of the stretching ratio is preferably 3.5 times, more preferably 3.0 times, even more preferably 2.8 times, particularly preferably 2.7 times, and most preferably 2.6 times.

[0067] When stretched in the MD direction at a stretching ratio of 4.5 times or less, a uniaxially oriented MD film is obtained in which crystallization progresses appropriately and the stretchability in the TD direction is excellent. Then, by stretching the obtained uniaxially oriented MD film in the TD direction, stretching unevenness is suppressed, and a biaxially oriented film is obtained in which the thickness accuracy and transparency are excellent, and the tensile elongation at break in the MD direction is high.

[0068] Furthermore, if the stretching ratio in the MD direction is 2.0 times or higher, the occurrence of stretching unevenness can be suppressed, and a stretched film with uniform thickness and high flatness can be obtained.

[0069] The stretching speed is preferably such that the stretching strain rate in the MD direction exceeds 400% / min, more preferably 800 to 12000% / min, and even more preferably 1200 to 6000% / min. Stretching at a stretching strain rate exceeding 400% / min prevents the film from breaking during stretching due to crystal growth. Furthermore, stretching at a stretching strain rate of 12000% / min or less allows the film to deform in response to the applied stress, thus preventing the film from breaking.

[0070] From the viewpoint of suppressing film breakage and producing biaxially oriented films with good yield, the stretching temperature is preferably (Tg-5)°C or higher, and more preferably (Tg)°C or higher, based on the glass transition temperature (Tg) of the semi-aromatic polyamide. Furthermore, from the viewpoint of suppressing the occurrence of stretching irregularities, 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.

[0071] For example, in the case of polyamide 9T film (Tg of polyamide 9T = 125°C), the stretching temperature is preferably 120 to 175°C, more preferably 120 to 170°C, and even more preferably 125 to 160°C. (Preheating process) The preheating process is a process of preheating the film before the stretching process (unstretched film in the case of simultaneous biaxial stretching, and uniaxially stretched film in the MD direction in the case of sequential biaxial stretching). Film preheating temperature T １ From the viewpoint of suppressing sagging, the preheating temperature 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. １ The lower limit of the preheating temperature is preferably (Tg-6)°C, more preferably (Tg-5°C). １ The upper limit is preferably (Tg+4)°C, more preferably (Tg+1)°C, even more preferably (Tg)°C, and particularly preferably (Tg-1)°C.

[0072] If the preheating temperature of the film is below (Tg-9)°C, the resulting film tends to have a large amount of sag at the edges. Conversely, if the preheating temperature of the film exceeds (Tg+5)°C, the resulting film tends to have a large amount of sag in the middle.

[0073] If the preheating process involves preheating the film while gradually changing the temperature, it is preferable that the preheating temperature immediately before the stretching process is within the aforementioned range.

[0074] For example, in the case of polyamide 9T film (Tg of polyamide 9T = 125°C), the preheating temperature of the polyamide 9T film is T １ The preheating temperature T is preferably in the range of 116 to 130°C. １ The lower limit of the preheating temperature T is preferably 119°C, more preferably 120°C. １ The upper limit is preferably 129°C, more preferably 126°C, even more preferably 125°C, and particularly preferably 124°C.

[0075] In this invention, sagging can be suppressed by preheating the film within the specified temperature range. The principle by which sagging is suppressed by adjusting the preheating temperature of the film is not clear, but it is thought that sagging is suppressed by controlling the bowing phenomenon.

[0076] When manufacturing film using the tenter stretching method, a bowing phenomenon occurs due to the stress generated in the film at the boundary between the stretching section and the heat-setting section. Specifically, when manufacturing stretched film using the tenter stretching method, the film passes through the preheating section, stretching section, heat-setting section, relaxation section, and cooling section, but the stretching stress is maximum near the end of the stretching section, that is, at the point where the set stretching ratio is reached. At this time, since both ends of the film are held by clips inside the tenter, a phenomenon occurs in which the central part of the film is pulled towards the end of the stretching section. Then, the central part of the film is pulled from the heat-setting section following the stretching section towards the stretching section, so when a straight line drawn perpendicular to the direction of film travel before entering the stretching machine comes out of the stretching machine, a bowing phenomenon occurs in which the central part of the film draws an arc in the opposite direction to the direction of film travel. Due to this phenomenon, the effective stretching ratio in the direction of film travel differs between the central part of the film and both ends, and this is thought to affect the slack of the film. Furthermore, it is presumed that controlling the temperature of the preheating and cooling sections within a specific range will suppress the occurrence of the bowing phenomenon, thereby suppressing sagging. (Stretching process) The stretching process is a process of stretching a film to obtain a biaxially oriented film. If the film used in this process is an unstretched film, the process involves simultaneously biaxially stretching the unstretched film in the MD and TD directions. If the film used in this process is a uniaxially oriented film in the MD direction, the process involves stretching the uniaxially oriented film in the MD direction in the TD direction.

[0077] When a uniaxially oriented film in the MD direction is stretched in the TD direction (sequentially biaxially oriented), 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.

[0078] When the stretching ratio in the TD direction is within the aforementioned range, it is possible to suppress the occurrence of stretching unevenness, obtain a biaxially oriented film that has excellent thickness accuracy and transparency, and high tensile elongation at break in the TD direction.

[0079] When an 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.

[0080] Stretching in the MD direction at a stretching ratio of 4.5 times or less yields a stretched film with low thermal shrinkage and excellent dimensional stability. Furthermore, stretching in the TD direction at a stretching ratio of 5.0 times or less yields a stretched film with low thermal shrinkage, excellent dimensional stability, and even higher tensile elongation at break.

[0081] Furthermore, if the stretching ratio in the MD and TD directions is 2.0 times or more, the occurrence of stretching unevenness can be suppressed, and a stretched film with uniform thickness and high flatness can be obtained.

[0082] In the simultaneous biaxial stretching method, when obtaining a biaxially oriented film with a thickness of 1 to 25 μm, 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 oriented 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.

[0083] The stretching speed is preferably such that the stretching strain rate in both the MD and TD directions exceeds 400% / min, more preferably between 800 and 12000% / min, and even more preferably between 1200 and 6000% / min. Stretching at a stretching strain rate exceeding 400% / min prevents the film from breaking during stretching due to crystal growth. Furthermore, stretching at a stretching strain rate of 12000% / min or less allows the film to deform in response to the applied stress, thus preventing the film from breaking.

[0084] From the viewpoint of suppressing film breakage and producing biaxially oriented films with good yield, the stretching temperature is preferably (Tg-5)°C or higher, and more preferably (Tg)°C or higher, based on the glass transition temperature (Tg) of the semi-aromatic polyamide. Furthermore, from the viewpoint of suppressing the occurrence of stretching irregularities, 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.

[0085] For example, in the case of polyamide 9T film (Tg of polyamide 9T = 125°C), the stretching temperature is preferably 120 to 160°C, and more preferably 125 to 155°C. Also, when the heating temperature of the stretching process is divided into two zones, the stretching temperature for the first half is preferably 120 to 140°C, and more preferably 125 to 135°C. The stretching temperature for the second half is preferably above 135°C and below 160°C, more preferably 140 to 160°C, and particularly preferably 145 to 155°C. (Heat setting process) After the stretching described above, it is preferable to perform a heat setting treatment on the semi-aromatic polyamide film while holding the film with the clips used during stretching. By performing a heat setting treatment, the resulting film can have its thermal shrinkage rate reduced without the occurrence of heat-induced unevenness. The heat-setting temperature is preferably in the range of (Tm-30)°C to (Tm)°C, 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, based on the melting point (Tm) of the semi-aromatic polyamide. If the heat-setting temperature is (Tm-30)°C or higher, a film with low thermal shrinkage can be obtained. If the heat-setting temperature is (Tm)°C or lower, it is possible to suppress appearance defects such as heat-induced wrinkles and breakage during the heat-setting process, and a biaxially oriented film with high tensile elongation at break can be obtained.

[0086] For example, in the case of polyamide 9T film (Tm of polyamide 9T = 290°C), the heat-fixing treatment temperature is preferably 260 to 290°C, more preferably 263 to 287°C, and even more preferably 266 to 284°C.

[0087] Known methods for heat setting include, for example, blowing hot air, irradiating with infrared rays, and irradiating with microwaves. Among these, blowing hot air is preferred because it can heat uniformly and accurately. (Relaxation process) After the heat setting process, it is preferable to relax the film in the MD and TD directions at the same temperature as the heat setting process while it is still held in place by the clip.

[0088] 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%. By performing relaxation treatment in the MD and TD directions at the aforementioned relaxation rates, it is possible to obtain a film with reduced thermal shrinkage and improved dimensional stability while suppressing sagging.

[0089] In the sequential biaxial stretching method, when obtaining a biaxially oriented film with a thickness of 1 to 50 μm, the relaxation ratio 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 oriented film with a thickness of 51 to 150 μm, the relaxation ratio is preferably 1.0 to 3.0% in the MD direction and 1.0 to 10.0% in the TD direction.

[0090] 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.

[0091] In the simultaneous biaxial stretching method, the relaxation process can be performed inline for the MD and TD directions simultaneously or separately. When performed separately, it can be done by relaxing the MD direction first, followed by the TD direction, or by relaxing the TD direction first, followed by the MD direction.

[0092] On the other hand, in the sequential biaxial stretching method, the relaxation treatment can be performed simultaneously in line in the MD and TD directions after (i) stretching in the MD direction and then stretching in the TD direction, followed by a heat-setting treatment, or (ii) stretching in the MD direction, followed by a relaxation treatment in the MD direction, then stretching in the TD direction, followed by a heat-setting treatment, and then a relaxation treatment in the TD direction. However, in (ii), if the heat-setting treatment is performed after stretching in the MD direction and the relaxation treatment in the MD direction, the resulting film will be difficult to stretch in the TD direction, so it is not preferable to perform the heat-setting treatment before stretching in the TD direction. Furthermore, in the sequential biaxial stretching methods described in (i) and (ii) above, stretching in the MD direction is performed first, followed by stretching in the TD direction, but in the sequential biaxial stretching method, stretching in the TD direction is also acceptable, followed by stretching in the MD direction.

[0093] Alternatively, the above relaxation process can also be performed by relaxing the film in the TD direction in-line after biaxial stretching, winding it up, and then passing it through a drying oven set to a predetermined temperature under low tension offline to perform relaxation in the MD direction. (Cooling process) The cooling process is a process of cooling the stretched film. Cooling temperature T ２ The cooling temperature is preferably in the range of (Tm-260)°C to (Tm-170)°C, based on the melting point (Tm) of the semi-aromatic polyamide. From the viewpoint of suppressing sagging, the cooling temperature T ２ The lower limit of cooling temperature T is preferably (Tm-245)°C, more preferably (Tm-240)°C, more preferably (Tm-235)°C, even more preferably (Tm-230)°C, particularly preferably (Tm-225)°C, and most preferably (Tm-220)°C. ２ The upper limit is preferably (Tm-180)°C, more preferably (Tm-185)°C, even more preferably (Tm-190)°C, particularly preferably (Tm-195)°C, and most preferably (Tm-200)°C.

[0094] For example, in the case of polyamide 9T film (Tm of polyamide 9T = 290°C), the cooling temperature T ２ For example, the temperature is 30 to 120°C. From the viewpoint of suppressing sagging, the cooling temperature T ２The lower limit of the cooling temperature T is preferably 45°C, more preferably 50°C, more preferably 55°C, even more preferably 60°C, particularly preferably 65°C, and most preferably 70°C. ２ The upper limit is preferably 110°C, more preferably 105°C, even more preferably 100°C, particularly preferably 95°C, and most preferably 90°C.

[0095] In manufacturing the semi-aromatic polyamide film of the present invention by sequential biaxial stretching, the preheating temperature T is chosen to adjust the refractive index in the MD direction to a specific range at the central, left, and right ends of the resulting film in the TD direction. １ (℃) and cooling temperature T ２ The temperature (°C) preferably satisfies formula (4) below, more preferably satisfies formula (4-1) below, and even more preferably satisfies formula (4-2) below.

[0096] 1073 ≤ 10 × T １ -T ２ ≤1211 (4) 1085 ≤10 × T １ -T ２ ≤1200 (4-1) 1096 ≤10 × T １ -T ２ ≤1188 (4-2) The thickness of the semi-aromatic polyamide film of the present invention can be appropriately changed depending on the application and purpose, but is preferably 1 to 150 μm, more preferably 10 to 100 μm, and even more preferably 20 to 80 μm.

[0097] The semi-aromatic polyamide film of the present invention can be manufactured using methods such as flat sequential biaxial stretching, flat simultaneous biaxial stretching, and tubular stretching. Examples of stretching equipment for implementing flat simultaneous biaxial stretching include screw type tenters, pantograph type tenters, and linear motor driven clip type tenters.

[0098] Furthermore, in the apparatus for manufacturing the semi-aromatic polyamide film of the present invention, it is preferable that the surfaces of the cylinder, barrel melting section, metering section, single pipe, filter, T-die, etc., are treated to reduce surface roughness in order to prevent resin accumulation. Methods for reducing surface roughness include, for example, modifying the surface with a low-polarity substance or depositing silicon nitride or diamond-like carbon onto the surface.

[0099] The resulting semi-aromatic polyamide film may be in the form of a single sheet or in the form of a film roll wound onto a winding roll. The film roll form may also include a raw material roll obtained by winding a film obtained through preheating, stretching, and cooling processes onto a winding roll, and a slit roll obtained by slitting a raw material roll to a desired width.

[0100] The semi-aromatic polyamide film may be a single-layer film or a multilayer structure consisting of two or more layers laminated together.

[0101] When a semi-aromatic polyamide film has a multilayer structure, a lubricant can be included in at least one layer. However, in the case of a two-layer film, it is preferable to include a lubricant in one of the layers, and in the case of a three-layer film, it is preferable to include a lubricant in each of the layers located on both surfaces. This makes it easier to control the surface roughness of the semi-aromatic polyamide film. The type of lubricant and the amount of lubricant can be adjusted as appropriate depending on the application.

[0102] The surface of the semi-aromatic polyamide film may be subjected to corona treatment, plasma treatment, acid treatment, flame treatment, or the like to improve adhesion with other materials.

[0103] The semi-aromatic polyamide film of the present invention may have layers laminated on it made of inorganic materials such as metals and their oxides, other polymers, paper, woven fabrics, nonwoven fabrics, wood, etc. <Applications> 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 applications such as various electronic materials and optical components.

[0104] The semi-aromatic polyamide film of the present invention can be used specifically as a packaging material for pharmaceuticals; a packaging material for food products such as retort foods; a packaging material for electronic components such as semiconductor packages; an electrical insulating material for motors, transformers, cables, etc.; a dielectric material for capacitor applications, etc.; a material for magnetic tapes such as cassette tapes, magnetic tapes for digital data storage, and video tapes; a protective board for solar cell substrates, liquid crystal panels, conductive films, and display devices; an electronic circuit board material such as LED mounting substrates, substrates for flexible printed wiring, and flexible flat cables; a heat-resistant tape such as coverlay film for flexible printed wiring, heat-resistant masking tape, and industrial process tape; a heat-resistant barcode label; a heat-resistant reflector; an insulating tape; various release films; a heat-resistant base film; a photographic film; a molding material; an agricultural material; a medical material; a civil engineering and construction material; a filtration membrane, and other films for household and industrial use.

[0105] Furthermore, because the semi-aromatic polyamide film of the present invention has excellent heat resistance, dimensional stability, and transparency, it can be used in applications such as display materials and display devices in mobile devices. Specifically, it can be used as a base film for various functional materials such as optical substrates, polarizing plates, and phase difference plates in various displays such as liquid crystal displays and organic EL displays, as well as a protective film and sealing film for light-emitting elements and display devices.

[0106] [Electronic Material] The electronic material of the present invention comprises at least the above-mentioned semi-aromatic polyamide film.

[0107] The aforementioned electronic materials include, for example, packaging materials for electronic components such as semiconductor packages; electrical insulating materials for motors, transformers, cables, etc.; dielectric materials for capacitor applications, etc.; materials for magnetic tapes such as cassette tapes, magnetic tapes for digital data storage, and video tapes; and heat-resistant masking tapes, heat-resistant reflectors, insulating tapes, release films, etc.

[0108] [Optical component] The optical component of the present invention comprises at least the above-mentioned semi-aromatic polyamide film.

[0109] The optical components include, for example, solar cell substrates, liquid crystal panels, conductive films, protective plates and protective films for display devices, etc.; electronic circuit board materials such as LED displays, OLED displays, LED mounting boards, boards for flexible printed wiring, and flexible flat cables; coverlay films for flexible printed wiring, insulating tapes, release films, polarizing plates, base films, protective films for light-emitting elements and display devices, sealing films, etc.

[0110] The configurations and combinations thereof described above are merely examples, and additions, omissions, substitutions, and modifications to the configurations are permitted as appropriate, without departing from the spirit of the present invention. Furthermore, the present invention is not limited by its embodiments.

[0111] The present invention will be specifically described below with reference to examples. 1. Evaluation Method (1) Intrinsic viscosity of semi-aromatic polyamide Intrinsic viscosity (η) of the resin at concentrations of 0.05, 0.1, 0.2, and 0.4 g / dL in concentrated sulfuric acid at 30°C ｉｎｈ The intrinsic viscosity [η] was obtained by calculating the following formula and extrapolating it to a concentration of 0.

[0112] η ｉｎｈ = [ln(t １ / t ０ )] / c (where η ｉｎｈ is the intrinsic viscosity (dL / g), t ０ t is the time the solvent flows down (in seconds). １(1) The time it takes for the resin solution to flow (seconds), and c represents the concentration of the resin in the solution (g / dL). (2) Melting point Tm and glass transition temperature Tg of semi-aromatic polyamide Using a differential scanning calorimeter (PerkinElmer DSC-7), 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 (1st Scan), then cooled from 350°C to 20°C at a rate of 100°C / min and held for 5 minutes. The glass transition temperature during the process of further heating from 20°C to 350°C at a rate of 10°C / min (2nd Scan) was defined as the Tg of the semi-aromatic polyamide. Similarly, the peak top temperature of the crystal melting peak observed in the 2nd Scan was defined as Tm. (3) Crystallization heat of unstretched film A 10 mg unstretched sheet of semi-aromatic polyamide was heated from 40°C to 350°C at a rate of 20°C / min using a differential scanning calorimeter (PerkinElmer DSC-7) in a nitrogen atmosphere (1st Scan), and the heat of the resulting exothermic peak was determined. (4) Heat shrinkage rate of semi-aromatic polyamide film MD direction test specimens (MD direction length 100 mm × TD direction width 10 mm) and TD direction test specimens (TD direction length 100 mm × MD direction width 10 mm) were cut from the semi-aromatic polyamide film. Each of the obtained test specimens was left in a 250°C atmosphere for 5 minutes, then subjected to a treatment at a temperature of 23°C and humidity of 50% RH for 2 hours, and the length dimension after treatment was measured. The heat shrinkage rate S of the MD direction test specimen was calculated using the following formula. ＭＤ and the thermal shrinkage rate S of the test specimen in the TD direction ＴＤ They sought it.

[0113] Heat shrinkage rate (%) = [{length before treatment - length after treatment} / length before treatment] × 100 (5) A sample was taken from one circumference of the surface layer of a 400 mm diameter film roll obtained in the examples and comparative examples of refractive index of semi-aromatic polyamide film.

[0114] The refractive index n in the MD direction at three points located on a line parallel to the TD direction of the obtained sample was determined using an Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in accordance with JIS K7142. A sodium D-line was used as the light source, a test piece with a refractive index of 1.74 was used, and methylene iodide was used as the intermediate solution.

[0115] More specifically, the refractive index n in the MD direction at the center of the sample Ｃ , the refractive index n in the MD direction at a position 10% inside the sample width from the left end of the sample Ｌ , and the refractive index n in the MD direction at a position 10% inside the sample width from the right end of the sample Ｒ were measured.

[0116] Then, the refractive index difference n Ｄ was obtained from the following formula (1).

[0117] Refractive index difference n Ｄ = { (n Ｃ - n Ｌ [[ID=2-1]] ) - (n Ｃ - n Ｒ )} / 2 (1) Also, the average refractive index n Ａｖ was obtained from the following formula (2).

[0118] Average refractive index n <00000-2> = (n Ｃ + n Ｌ + n Ｒ ) / 3 (2) (6) One round of the surface layer was cut out from a film roll with a sag diameter of 400 mm and used as a sample. The obtained sample was released from the tension during winding and spread on a plane, and the length in the MD direction was measured at 50 mm intervals from one end to the other end along one side in the TD direction. From the maximum value L ｍａｘ and the minimum value L ｍｉｎ of the length, the sag amount was obtained by the following formula (3) (see Figure 1). <!-

[0119] Sag amount (‰) = (L ｍａｘ - L ｍｉｎ ) ÷ L ｍａｘ × 1000 (3) 2. Raw materials (1) Semi-aromatic polyamide The semi-aromatic polyamide A obtained in the following Production Example 1 was used.

[0120] Note: There seems to be an error in the original text where 'n Ａｖ ' is written as 'n<00000-2>' in the translation of line 31. It should be corrected to 'n Ａｖ '. Also, '<!-

[0119] ' in the original text might be an incorrect tag and should be checked for accuracy. The translation is done as accurately as possible based on the provided rules.Production Example 1 (Production of Semi-Aromatic Polyamide A) 3289 parts by mass of terephthalic acid (TPA), 2533 parts by mass of 1,9-nonanediamine (NDA), 633 parts by mass of 2-methyl-1,8-octanediamine (MODA), 48.9 parts by mass of benzoic acid (BA), 6.5 parts by mass of sodium hypophosphate monohydrate (0.1% by mass relative to the total of the four polyamide raw materials), and 2200 parts by mass of distilled water were placed in a reaction vessel and purged with nitrogen. The molar ratio of these raw materials (TPA / BA / NDA / MODA) was 99 / 2 / 80 / 20.

[0121] The contents of the reaction vessel were stirred at 100°C for 30 minutes, and then the internal temperature was raised to 210°C over 2 hours. At this time, the internal pressure of the reaction vessel was raised to 2.12 MPa. The reaction continued for 1 hour, then the temperature was raised to 230°C, and the temperature was maintained at 230°C for the next 2 hours, during which the reaction was carried out while gradually releasing the 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 was continued for another hour to obtain a prepolymer. This was dried at 100°C under reduced pressure for 12 hours, and then pulverized to a size of 2 mm or less.

[0122] Next, the pulverized prepolymer was solid-state polymerized for 10 hours under conditions of a temperature of 230°C and a pressure of 13.3 Pa to obtain a polymer. The obtained polymer was supplied to a twin-screw extruder, melt-kneaded and extruded under conditions of a cylinder temperature of 320°C, cooled and cut to produce pelletized semi-aromatic polyamide A. The obtained semi-aromatic polyamide A had an intrinsic viscosity of 1.17 dL / g, a melting point (Tm) of 290°C, and a glass transition temperature (Tg) of 125°C. (2) Silica master tip (MI) of semi-aromatic polyamide A The master tip (MI) obtained in the following production example 2 was used.

[0123] Manufacturing Example 2 (Manufacturing of Master Tip (M1)) 98 parts by mass of semi-aromatic polyamide A obtained in Manufacturing Example 1 and 2 parts by mass of silica (Silysia 310P manufactured by Fuji Silysia Chemical Co., Ltd., average particle size 2.7 μm) were melt-kneaded to produce a master tip (M1) containing 2% by mass of silica.

[0124] Example 1 A mixture was obtained by mixing 100 parts by mass of semi-aromatic polyamide A with 0.2 parts by mass of a heat-resistant stabilizer (Sumirizer GA-80 manufactured by Sumitomo Chemical Co., Ltd.) and 0.1 parts by mass of silica.

[0125] The resulting mixture was melted in a 65 mm single-screw extruder with the cylinder temperature set to 295°C (first stage), 320°C (middle stage), and 320°C (last stage). It was then extruded into a sheet through a T-die set to 320°C, and cooled by electrostatic contact on a cooling roll set to a surface temperature of 40°C to obtain a substantially unoriented, unstretched sheet with a thickness of 230 μm (crystallization heat of 27 J / g).

[0126] Next, the obtained unstretched sheet was biaxially stretched using a flat-type sequential stretcher.

[0127] First, using a heating roll and an infrared heater, the heating roll was heated to 110°C, and then, while heating the space to 150°C with the infrared heater, the unstretched film was stretched in the MD direction at a stretching ratio of 2.5 times to obtain a uniaxially oriented film in the MD direction.

[0128] Next, the uniaxially stretched film in the MD direction was guided to the TD direction stretching machine while both ends were held with clips. Then, the uniaxially stretched film in the MD direction was heated to a preheating temperature (T) in the preheating section inside the TD direction stretching machine. １ The material was preheated to 123°C, and the stretched section was stretched in the TD direction at a stretching temperature of 130°C and a stretching ratio of 3.4 times.

[0129] After stretching, the heat-fixed portion was heat-set at 279°C.

[0130] Subsequently, in the relaxed section, a relaxation treatment was 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.

[0131] Subsequently, the cooling temperature (T) in the cooling section ２ It was cooled to 80°C.

[0132] This resulted in a semi-aromatic polyamide film with a thickness of 27 μm. The obtained film was then wound up to obtain a film roll with a width of 1200 mm and a diameter of 400 mm.

[0133] Examples 2-8 and Comparative Examples 1-5 were obtained in the same manner as in Example 1, except that the preheating temperature, stretching method, stretching ratio, relaxation rate, and cooling temperature were changed as shown in Table 1.

[0134] Examples 1 to 7 show that when the film is preheated to a predetermined temperature before stretching and cooled to a predetermined temperature after stretching, the refractive index difference n of the resulting semi-aromatic polyamide film is Ｄ It is possible to adjust the coefficient to a predetermined range, and it is found that a semi-aromatic polyamide film with excellent dimensional stability under high-temperature conditions and sufficiently small sag can be obtained. Furthermore, by controlling the cooling temperature after stretching to a more favorable range, the refractive index difference n can be increased. Ｄ This yields a semi-aromatic polyamide film within the most desirable range, and it can be found that the amount of sagging can be further reduced.

[0135] Furthermore, a comparison of Examples 1-7 and Example 8 shows that by adjusting the heat-setting treatment temperature, a semi-aromatic polyamide film with less sagging and excellent dimensional stability under high-temperature conditions can be obtained.

[0136] On the other hand, the semi-aromatic polyamide films obtained in Comparative Examples 1 to 5 have a refractive index difference n Ｄ Because it did not meet the range defined in this invention, the amount of sagging was large.

Claims

1. A semi-aromatic polyamide film having sides along the MD direction and sides along the TD direction, wherein the refractive index difference n calculated from the following formula (1) Ｄ is -0.0010 to 0.0045. The refractive index difference n Ｄ = { (n Ｃ - n Ｌ ) - (n Ｃ - n Ｒ )} / 2 (1) (In the formula, n Ｃ is the refractive index in the MD direction at the central part of the film, n Ｌ is the refractive index in the MD direction at a position within the film width of 10% from the left end of the film, and n Ｒ is the refractive index in the MD direction at a position within the film width of 10% from the right end of the film. Incidentally, the central part, the left end part, and the right end part are located on the same line parallel to the TD direction of the film) 2. The average refractive index n calculated from the following formula (2) Ａｖ A semi-aromatic polyamide film according to claim 1, wherein the refractive index average n is 1.5985 to 1.6045. Ａｖ = (n Ｃ +n Ｌ +n Ｒ ) / 3 (2) (where n Ｃ , n Ｌ , and n Ｒ (This is the same as above.) 3. The semi-aromatic polyamide film according to claim 1, wherein the amount of sag measured by the following measurement method is 3.0‰ or less. <Method for measuring the amount of sag> Measure the length in the MD direction in 50 mm increments from one end to the other of one side along the TD direction, and calculate the amount of sag from the maximum and minimum values ​​of the length using the following formula (3). Amount of sag (‰) = (maximum value - minimum value) ÷ maximum value × 1000 (3) 4. The thermal shrinkage rate S in the MD direction is determined by measuring the dimensions after leaving the material in a 250°C atmosphere for 5 minutes, followed by leaving it in a 23°C and 50% RH atmosphere for 2 hours. ＭＤ and the thermal shrinkage coefficient S in the TD direction ＴＤ The semi-aromatic polyamide film according to claim 1, wherein each of these is -1.0 to 1.5%.

5. A method for producing a semi-aromatic polyamide film, comprising the steps of [1] or [2] below to obtain the semi-aromatic polyamide film described in any one of claims 1 to 4. [1] A step of preheating an unstretched semi-aromatic polyamide film at a temperature of (Tg-9)°C to (Tg+5)°C based on the glass transition temperature Tg of the semi-aromatic polyamide; a step of simultaneously stretching the film in the MD direction and the TD direction; and a step of cooling the film at a temperature of (Tm-260)°C to (Tm-170)°C 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)°C to (Tg+5)°C based on the Tg of the semi-aromatic polyamide; a step of stretching the film in the TD direction; and a step of cooling the film at a temperature of (Tm-260)°C to (Tm-170)°C based on the melting point Tm of the semi-aromatic polyamide.

6. An electronic material comprising a 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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