JP2005162805A - Aromatic polyamide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aromatic polyamide film which seldom causes uneven release from the support and has high heat resistance and transparency. <P>SOLUTION: The aromatic polyamide film contains 0.01-5 pts.wt. releasing agent to 100 pts.wt. polymer and light transmittance of ≥80% to the light with a wavelength of 450 nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aromatic polyamide film which is less likely to cause unevenness when peeled from a support and has high heat resistance and transparency.

  Colorless and transparent materials have been studied in various ways depending on their various uses such as optical lenses, functional optical films, and disk substrates. However, as the information equipment is rapidly becoming smaller and lighter and display elements are becoming more precise, the materials themselves The functions and performance required for the products are becoming increasingly precise and sophisticated.

  Especially for films, it is used for materials that use image display elements such as polarizing plates, retardation plates, and substrates for transparent electrodes. However, optical unevenness in the film leads to uneven color on the screen, so advanced control is required. It is.

  In recent years, the demand for high heat resistance of optical films has been increasing. For example, in-vehicle films require thermal stability at about 120 ° C. Moreover, when performing processes, such as vapor deposition and sputtering, on the film surface, it may be desirable to maintain film temperature at 300 degreeC or more.

  An aromatic polyamide film is mentioned as a film with high heat resistance. Aromatic polyamide film has high heat resistance and mechanical strength, and sufficiently satisfies the heat resistance and mechanical strength required for optical films, but para-oriented aromatic polyamide such as PPTA is colored yellow and optical Deployment to applications has been difficult. For example, although disclosed in Patent Document 1 as a heat-resistant transparent conductive film, the film of the invention also has practically low transmittance at a wavelength of 600 nm of 71% and lower transmittance on the lower wavelength side in Examples. It was not right.

  The aromatic polyamide film is formed into a film by a so-called solution casting method. However, depending on the polymer to be cast, the adhesive strength with the support is strong, and unevenness at the time of peeling may occur. In some cases, unevenness occurred.

Regarding improvement of peelability in solution casting, Patent Document 2 discloses an example in which a phosphoric acid ester compound is added to a polymer solution and a film is formed by a dry casting method. The aromatic polyamide film is formed by a so-called dry / wet film forming method in which a polymer sheet after drying / peeling is introduced into water to remove a solvent or a salt generated by neutralization in the polymer sheet. When a release agent is used, there is a problem that the film surface is roughened in this wet process and the transmittance is lowered.
Japanese Patent Publication No. 7-89452 Japanese Patent No. 2670916

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue. That is, an object of the present invention is to provide an aromatic polyamide film which is less likely to cause unevenness when peeled from a support and has high heat resistance and transparency.

  The present invention for achieving the above-described object includes an aromatic polyamide and a release agent, wherein the content of the release agent is 0.01 to 5 parts by weight with respect to 100 parts by weight of the aromatic polyamide and has a wavelength of 450 nm. An aromatic polyamide film having a light transmittance of 80% to 100% is characterized.

  The aromatic polyamide film of the present invention is less likely to cause unevenness when peeled from the support and has high heat resistance and transparency, and thus can be applied to optical members such as image display elements and optical disk substrates.

  The aromatic polyamide film of the present invention has a light transmittance of 80% to 100% for light having a wavelength of 450 nm. If the light transmittance with respect to light having a wavelength of 450 nm is less than 80%, the film is colored yellow and may not be used as an optical member such as an image display element or an optical disk substrate. Since the transparency is further improved, the light transmittance is more preferably 85% or more and 100% or less, and still more preferably 90% or more and 100% or less.

  In addition, the aromatic polyamide film of the present invention preferably has a light transmittance of 400 nm light of 60% or more. More preferably, the light transmittance of 400 nm light is 65% or more, more preferably 75% or more, and most preferably 90% or more. When the light transmittance at 400 nm in the near ultraviolet region is 60% or more, the transparency of the film is remarkably improved.

  The aromatic polyamide film of the present invention contains an aromatic polyamide and a release agent, but contains 0.01 to 5 parts by weight of the release agent with respect to 100 parts by weight of the aromatic polyamide. When the content of the release agent is less than 0.01 parts by weight, the adhesion between the polymer sheet and the support is strong, and there may be a stepped unevenness at the time of peeling or an optical unevenness in the film. . When the content of the release agent is 5 parts by weight or more, the light transmittance may decrease or the release agent may bleed out. The content of the release agent is more preferably 0.02 to 3 parts by weight, still more preferably 0.03 to 1 part by weight. Here, the polymer sheet refers to a self-supporting film or sheet containing a solvent, a dissolution aid, and the like in addition to the polymer.

  The release agent in the present invention will be described below, but the type, addition amount, and addition method of the release agent should be appropriately selected depending on the polymer (aromatic polyamide), the solvent, the support material, etc., and are not particularly limited. Examples of the polymer include an aromatic polyamide having a sulfonic group in the molecule, an aromatic polyamide having a fluorene group in the molecule, and an aromatic polyamide having a trifluoromethyl group in the molecule. Examples of the support include a stainless steel endless belt having a mirror-finished surface. The release agent in the present invention is not particularly limited as long as it does not adversely affect the optical properties such as transparency and reduces the adhesion between the support and the polymer sheet, but a commercially available surfactant is preferably used. . Many types of surfactants are known for anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc., but high releasability is obtained. Fluorine surfactants do not adversely affect the optical properties, and phosphate ester surfactants are preferably used. A fluorosurfactant means a surfactant containing a fluorocarbon group. Specifically, for example, BM-1000, BM-1100 (manufactured by BM Chemie), Recommont FN901 (manufactured by Clariant Japan), Zeffle GH700 (manufactured by Daikin Corporation), F-top EF301, EF303, EF352 (new) Akita Kasei Co., Ltd.), Dry Film RA, Zonyl UR (DuPont Co., Ltd.), MegaFuck F142D, F171, F173, F183 (Dainippon Ink Co., Ltd.), Florard FC135, FC170C, FC403, FC430 FC431 (manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon KH20, KH40, S113, S131, S141, S382, S393, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), etc. It can be used a fluorine-based surface active agent commercially available under the name. Phosphate ester surfactants include triphenyl phosphate, tributyl phosphate, reticin, sodium dioleyl phosphate, diphenyl cresyl phosphate, phenyl dicresyl phosphate, resorcinol-bis (diphenyl phosphate), bisphenol A-bis (diphenyl phosphate) or the like can be used. The release agent may be used alone or in combination of two or more release agents.

  Since the aromatic polyamide film of the present invention has the structural units shown below, it can achieve both high mechanical properties such as high Young's modulus, surface hardness and glass transition temperature, and high transparency of the aromatic polyamide film. preferable. That is, the structural unit represented by the chemical formula (I), (II), (III) or (IV) is included (all of these structural units may be included, or only a part thereof may be included), And when the molar fractions of the structural units represented by the chemical formulas (I), (II), (III) and (IV) are l, m, n and o, respectively, the following formulas (1) to (3) It is preferable to be satisfied.

50 <l + m + n ≦ 100 (1)
0 ≦ l, m, n, o ≦ 100 (2)
0 ≦ o ≦ 50 (3)

R ¹ : a group having at least one 5-membered ring, 6-membered ring or 7-membered ring R ² : any aromatic group X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ³ : —CF ₃ , —CCl ₃ , —CBr ₃ , —OH, —F, —Cl, —OCH ₃ (however, structural units having these groups may be mixed in the molecule)
R ⁴ : any aromatic group

_{^{R 5: -SO 2 -, -}} O -, - CH 2 -, - C (CF 3) 2 - group selected from or _{-SO 2, -, - O -} , - CH 2 -, - C (CF 3 ₂ ) An aromatic group containing one or more groups selected from-.

R ^6: any aromatic group X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ⁷ : Arbitrary aromatic group R ⁸ : Arbitrary aromatic group X: Hydrogen, halogen, or a hydrocarbon group having 1 to 3 carbon atoms Chemical formulas (I), (II), (III) and (IV) are present respectively. Or not, but when the molar fractions of the structural units represented by the chemical formulas (I), (II) and (III) are 1, m and n, respectively, l + m + n is 50. It is a preferable aspect to exceed. More preferably, l + m + n is 80 or more, and most preferably l + m + n is 100. When l + m + n is 50 or less, the contribution of the structural unit contributing to coloring becomes larger than these effects, and a colorless transparent film may not be obtained (inferior in light transmittance).

  The coloration of aramid is believed to be due to intramolecular and intermolecular charge transfer complexes, but chemical formulas (I), (II) and (III) all inhibit the formation of intramolecular and intermolecular charge transfer complexes. The aramid film is considered to be colorless and transparent (to improve light transmittance).

In Chemical Formula (I), R ¹ is preferably a group having at least one 5-membered ring, 6-membered ring or 7-membered ring, and more preferably a cyclic group represented by Chemical Formula (XI). Most preferred is a fluorene group.

In the chemical formula (II), R ³ is —CF ₃ , —CCl ₃ , —CBr ₃ , —OH, —F, —Cl, —OCH ₃ (however, structural units having these groups are mixed in the molecule. Or the like may be suitably used. Most preferably -CF _3.

R ⁵ is, -SO ₂ in Formula (III) -, - O - , - CH 2 -, - C (CF 3) 2 - group selected from or _{-SO 2, -, - O -} , - CH 2 - An aromatic group containing one or more groups selected from —C (CF ₃ ) ₂ — is preferably used, and —SO ₂ — is most preferred.

  The plastic substrate of the present invention includes a structural unit represented by chemical formula (V), (VI), (VII) or (VIII), and has chemical formulas (V), (VI), (VII) and (VIII). It is preferable that the following formulas (5) to (7) are satisfied, where p, q, r, and s are the molar fractions of the structural unit represented by:

50 <p + q + r ≦ 100 (5)
0 ≦ p, q, r, s ≦ 100 (6)
0 ≦ s ≦ 50 (7)

  X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ⁹ : Arbitrary aromatic group R ¹⁰ : Arbitrary aromatic group The aromatic polyamide film of the present invention preferably has a variation in retardation value within 10 nm within the film plane. If the variation of the retardation value is within 10 nm, it is preferable because excellent display quality without color unevenness can be obtained when used as a birefringent film such as a liquid crystal display. The fluctuation of the phase difference value is more preferably within 6 nm.

  The aromatic polyamide film of the present invention preferably has a glass transition temperature (Tg) of 120 ° C. or higher. More preferably, it is 140 degreeC or more, More preferably, it is 180 degreeC or more. When the temperature is 120 ° C. or lower, the projector may not be used in a high-temperature environment such as a projector or a display device used in a car. In addition, when the film surface of the present invention is subjected to, for example, vapor deposition or sputtering, the substrate temperature may need to be used under high temperature conditions due to process restrictions. In this case, Tg is preferably 250 ° C. or higher. More preferably, it is 300 degreeC or more, More preferably, it is 350 degreeC or more, Most preferably, it is 400 degreeC or more. A higher Tg is preferable, but the upper limit is practically about 600 ° C.

  The aromatic polyamide film of the present invention preferably has a Young's modulus in at least one direction of 4 GPa or more and less than 20 GPa. More preferably, it is 8 GPa or more and less than 20 GPa. If the Young's modulus in all directions is less than 4 GPa, deformation may occur during processing, and the optical properties of the film may change. When the Young's modulus exceeds 20 GPa, the toughness of the film decreases, and film formation and processing may be difficult. When the Young's modulus in at least one direction is 4 GPa or more and less than 20 GPa, even if the thickness of the plastic substrate is reduced, it can resist the force applied during processing and use, and the planarity is further improved.

  The thickness of the aromatic polyamide film of the present invention is preferably 1 μm to 100 μm. More preferably, it is 2 μm to 50 μm. When the thickness of the film exceeds 100 μm, the light transmittance is lowered. Moreover, if the thickness of the film is less than 1 μm, the workability is lowered. By using aromatic polyamide as the substrate, it is possible to achieve high rigidity of the film, and excellent physical properties can be exhibited even with extremely thin films as compared with other materials. Needless to say, the thickness of the film should be appropriately selected depending on the application.

  Next, although the example of the manufacturing method of the aromatic polyamide of this invention and its composition, and the manufacturing method of an aromatic polyamide film is demonstrated below, this invention is not limited to this.

  Various methods can be used as a method for obtaining an aromatic polyamide solution, that is, a film-forming stock solution. For example, a low temperature solution polymerization method, an interfacial polymerization method, a melt polymerization method, a solid phase polymerization method and the like can be used. When it is obtained from a low temperature solution polymerization method, that is, from carboxylic acid dichloride and diamine, it is synthesized in an aprotic organic polar solvent.

  Examples of the carboxylic acid dichloride include terephthalic acid dichloride, 2chloro-terephthalic acid dichloride, isophthalic acid dichloride, naphthalene dicarbonyl chloride, biphenyl dicarbonyl chloride, and terphenyl dicarbonyl chloride. Most preferably, terephthalic acid dichloride is used. .

  In the aromatic polyamide solution, when acid dichloride and diamine are used as monomers, hydrogen chloride is by-produced. When neutralizing this, an inorganic neutralizing agent such as calcium hydroxide, calcium carbonate, lithium carbonate, Organic neutralizers such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine, and diethanolamine are used. The reaction between isocyanate and carboxylic acid is carried out in an aprotic organic polar solvent in the presence of a catalyst.

  When performing polymerization using two or more kinds of diamines, diamines are added one by one, 10 to 99 mol% of acid dichloride is added to the diamine and reacted, and then another diamine is added, Further, a stepwise reaction method in which acid dichloride is added and reacted, a method in which all diamines are mixed and added, and then acid dichloride is added and reacted can be used.

  Similarly, when two or more kinds of acid dichlorides are used, a stepwise method, a method of simultaneously adding them, and the like can be used. In any case, the molar ratio of the total diamine to the total acid dichloride is preferably 95 to 105: 105 to 95, and if this value is exceeded, the molecular weight of the resulting polymer will be low, and the elongation and toughness of the film will decrease. Sometimes.

  Examples of the aprotic polar solvent used in the production of the aromatic polyamide of the present invention include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide. Solvents, acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- or Phenolic solvents such as p-cresol, xylenol, halogenated phenol, and catechol, or hexamethylphosphoramide, γ-butyrolactone, and the like can be used. These are preferably used alone or as a mixture, but more preferably xylene, Toluene Using UNA aromatic hydrocarbons are also possible. Further, for the purpose of promoting the dissolution of the polymer, 50 wt% or less of an alkali metal or alkaline earth metal salt can be added to the solvent.

  The aromatic polyamide of the present invention contains 0.01 to 5 parts by weight of a release agent with respect to 100 parts by weight of the polymer (aromatic polyamide). As a method for adding the release agent, it is preferable to add a dispersion in which the release agent is dispersed in a solvent to the polymer solution after polymerization, and to stir and dissolve. If a release agent is added to the tank before polymerization, the polymerization reaction may be inhibited. Moreover, when a release agent is added directly to the polymer solution after polymerization, the release agent may not be sufficiently dissolved, leading to deterioration in peeling unevenness and light transmittance.

The aromatic polyamide of the present invention may contain 10% by weight or less of an inorganic or organic additive for the purpose of surface formation and processability improvement. The additive may be colorless or colored, but is preferably colorless and transparent so as not to impair the characteristics of the aromatic polyamide film of the present invention. Examples of additives for surface formation include inorganic particles such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaSO ₄ , BaSO ₄ , CaCO ₃ , carbon black, carbon nanotubes, fullerene, zeolite, and other metal fine powders. Etc. Preferred organic particles include, for example, particles made of an organic polymer such as crosslinked polyvinylbenzene, crosslinked acrylic, crosslinked polystyrene, polyester particles, polyimide particles, polyamide particles, and fluororesin particles, or the above organic polymer on the surface. Inorganic particles that have been subjected to treatment such as coating may be mentioned.

  Next, film formation will be described. The film-forming stock solution prepared as described above is formed into a film by a so-called solution casting method. The solution casting method includes a dry-wet method, a dry method, a wet method, etc., and any method may be used, but here, the dry-wet method will be described as an example.

  In the case of forming a film by a dry-wet method, the stock solution is extruded from a die onto a support such as a drum or an endless belt to form a thin film, and then the solvent is scattered from the thin film layer to form a polymer sheet having self-holding properties. Dry and peel until Drying conditions can be performed in the range of room temperature to 220 ° C. and within 60 minutes, for example. Moreover, it is preferable that the solvent content in the polymer sheet at the time of peeling is 30 to 75% by weight. When the solvent content is less than 30% by weight, the adhesion between the polymer sheet and the support becomes strong, and peeling may be difficult. Considering productivity, the solvent content at the time of peeling is preferably high, but if it exceeds 75% by weight, the self-supporting property of the polymer sheet is weak, and peeling unevenness and optical unevenness may occur. The solvent content in the polymer sheet at the time of peeling is more preferably 20 to 70% by weight, and further preferably 40 to 65% by weight.

  The polymer sheet peeled from the support is introduced into a wet process, and desalting, desolvation and the like are performed. In this wet process, the release agent in the vicinity of the film surface may be deposited to form a thin film on the film surface, thereby deteriorating the surface properties, and the transparency of the film may be impaired due to the inhibition of solvent and salt removal. is there. In this case, the formation of a thin film can be suppressed by using a mixed solution of alcohol and water as the extract in the wet bath, and deterioration of transparency can be prevented. The concentration of alcohol is preferably 0.5% by weight or more. Moreover, a bathtub may be divided | segmented with respect to the conveyance direction of a film, and the alcohol concentration in an extract may be reduced gradually.

  Further, stretching, drying, and heat treatment are performed to form a film. Stretching is in the range of 0.8 to 8 (drawing ratio is defined by dividing the film area after stretching by the area of the film before stretching. 1 or less means relaxation) as the stretching ratio. It is preferable that it is in 0.8, More preferably, it is 0.8-4. Moreover, as heat processing, the heat processing for several seconds to several minutes at 200 to 500 degreeC is implemented preferably. Below 200 ° C., heat treatment is not sufficient, and the surface hardness and Young's modulus of the film may decrease. Above 500 ° C, the film may be colored. The heat treatment temperature is more preferably 250 ° C to 400 ° C. Furthermore, it is effective to gradually cool the film after stretching or heat treatment, and it is effective to cool at a rate of 50 ° C./second or less. The film obtained from the aromatic polyamide of the present invention is not limited to a single layer film, and may be a laminated film. For example, high peelability and transparency can be obtained by laminating and casting using a solution containing a release agent only in the layer in contact with the support. Also, good releasability can be obtained by casting the polymer solution after applying the release agent to the support surface.

  Moreover, the composite film which gave various undercoat and surface treatment for the objectives, such as provision of gas barrier property, improvement of solvent resistance, and improvement of surface hardness, may be sufficient.

  Since the aromatic polyamide film of the present invention has little unevenness at the time of peeling and high heat resistance and transparency, it can be applied to optical members such as image display elements and optical disk substrates.

  The present invention will be described more specifically with reference to the following examples.

  The physical properties were measured and the effects were evaluated according to the following methods.

(1) Light transmittance The transmittance | permeability corresponding to the light of each wavelength was measured using UV measuring device U-3410 (made by Hitachi Measurement Co., Ltd.). Table 1 shows the light transmittance at a wavelength of 450 nm.

Transmittance (%) = (T1 / T0) × 100
However, T1 is the intensity | strength of the light which passed the sample, and T0 is the intensity | strength of the light which passed the air of the same distance except not passing a sample.

Wavelength range: 300 nm to 800 nm
Measurement speed: 120 nm / min Measurement mode: Transmission (2) Phase difference It measured using the following measuring device.

Apparatus: Cell gap inspection apparatus RETS-1100 (manufactured by Otsuka Electronics Co., Ltd.)
Measurement diameter: φ5mm
Measurement wavelength: 400 to 800 nm
The obtained 30 cm square samples were cut at 5 cm vertical and horizontal intervals to obtain 36 5 cm square measurement samples. The phase difference at the center of each measurement sample was measured, and the difference between the maximum value Rmax and the minimum value Rmin of the phase difference at the wavelength of 550 nm was defined as the fluctuation of the phase difference value.

(3) Film thickness It measured using the micro thickness meter (made by Anritsu).

  The thickness of the measurement sample used in the phase difference measurement was measured, and the average (n = 36) was obtained.

(4) Glass transition temperature (Tg)
The dynamic storage elastic modulus E ′ of the film was measured according to JIS K-7244-4 (1999/10/20) using DMS6100 (manufactured by Seiko Electronics Co., Ltd.), and from the inflection point of E ′ Tg was determined.

(5) Peelability evaluation The test for peeling the polymer sheet from the support was performed 10 times, and the number of times n1 when tearing or step-like unevenness occurred during peeling was evaluated according to the following criteria. However, a stainless steel plate having a mirror-finished surface was used as the support (surface roughness Ra: 0.5 nm), and the support was peeled off in the normal direction of the support at a peeling speed of 10 cm / second.

○: n1 = 0, 1
Δ: n1 = 2, 3
X: n1 = 4-10
(6) Transparency Evaluation The obtained film was compared with the film without the release agent added in Comparative Example 1 to evaluate the transparency by visual observation. A case where there was no difference in transparency was indicated as ◯, a case where there was transparency but a little inferior to the film of Comparative Example 1 was indicated as Δ, and a case where the film was whitened and clearly reduced in transparency was indicated as ×.

(7) Color unevenness evaluation Ten polymer sheets peeled in the peelability evaluation were subjected to extraction treatment and heat treatment to obtain a sample. This sample was sandwiched between polarizing plates and visually checked for color unevenness under crossed Nicols. did. The number of sheets where color unevenness was confirmed was n2, and evaluation was performed according to the following criteria.

○: n2 = 0, 1
Δ: n2 = 2, 3
X: n2 = 4-10
(Example 1)
In dehydrated N-methyl-2-pyrrolidone, 4,4′-diaminodiphenyl sulfone corresponding to 50 mol% and 3,3′-diaminodiphenyl sulfone corresponding to 50 mol% were dissolved, and 100 mol% was dissolved in this. The terephthalic acid dichloride corresponding to was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to obtain a polymer solution. In a separate container, dissolve the fluorosurfactant (Recommon FN901 (Clariant Japan)) in NMP and add 2 parts by weight of the surfactant to 100 parts by weight of the polymer. Added and stirred at 60 ° C. for 10 hours until completely dissolved. Thus, an aromatic polyamide solution A having a polymer concentration of 10% by weight was obtained.

  A part of the obtained polymer solution was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 7 minutes to obtain a self-holding film. The obtained film was peeled off from the stainless steel plate, fixed to a metal frame, washed in running water for 10 minutes, and further heat treated at 280 ° C. for 1 minute to obtain an aromatic polyamide film having a size of 30 cm square. The glass transition temperature of the film was 302 ° C. The physical properties of the obtained film were measured and are shown in Table 1.

(Example 2)
In dehydrated N-methyl-2-pyrrolidone, 4,4′-diaminodiphenyl sulfone corresponding to 50 mol% and 3,3′-diaminodiphenyl sulfone corresponding to 50 mol% were dissolved, and 100 mol% was dissolved in this. The terephthalic acid dichloride corresponding to was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to obtain a polymer solution. Dissolve triphenyl phosphate in NMP in a separate container and add to the polymer solution so that the amount of triphenyl phosphate added is 2 parts by weight with respect to 100 parts by weight of the polymer. Stir. Thus, an aromatic polyamide solution B having a polymer concentration of 10% by weight was obtained.

  A part of the obtained polymer solution was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 7 minutes to obtain a self-holding film. The obtained film is peeled off from the stainless steel plate and fixed to a metal frame, immersed in a water bath containing 5% ethanol for 10 minutes, then washed in running water for 10 minutes, and further subjected to heat treatment at 280 ° C. for 1 minute. A 30 cm square aromatic polyamide film was obtained. The physical properties of the obtained film were measured and are shown in Table 1.

(Example 3)
A part of the polymer solution B obtained in Example 2 was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 4 minutes to obtain a self-holding film. The obtained film is peeled off from the stainless steel plate and fixed to a metal frame, immersed in a water bath containing 5% ethanol for 10 minutes, then washed in running water for 10 minutes, and further subjected to heat treatment at 280 ° C. for 1 minute. A 30 cm square aromatic polyamide film was obtained. Since the drying time was short, the self-holding property of the polymer sheet was weak, and since the film was stretched at the time of peeling, the fluctuation of the retardation value became large. The physical properties of the obtained film were measured and are shown in Table 1.

Example 4
In Example 2, the amount of triphenyl phosphate added was 0.02 parts by weight with respect to 100 parts by weight of the polymer, and polymerization and film formation were performed in the same manner as in Example 2 except that. The physical properties of the obtained film were measured and are shown in Table 1.

(Example 5)
In Example 2, the amount of triphenyl phosphate added was 4 parts by weight with respect to 100 parts by weight of the polymer, and polymerization and film formation were performed in the same manner as in Example 2 except that. The physical properties of the obtained film were measured and are shown in Table 1.

(Example 6)
In Example 2, instead of triphenyl phosphate, a silicone surfactant (SH710 (manufactured by Toray Dow Corning)) was used, and other than that, polymerization and film formation were performed in the same manner as in Example 2. Peelability and transparency were slightly reduced. The physical properties of the obtained film were measured and are shown in Table 1.

(Example 7)
A part of the polymer solution B obtained in Example 2 was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 7 minutes to obtain a self-holding film. The obtained film was peeled off from the stainless steel plate, fixed to a metal frame, washed in running water for 10 minutes, and further heat treated at 280 ° C. for 1 minute to obtain an aromatic polyamide film having a size of 30 cm square. The release agent adhered to the film surface during washing with water, and the transparency of the film was slightly deteriorated by the subsequent heat treatment. The physical properties of the obtained film were measured and are shown in Table 1.

(Comparative Example 1)
In dehydrated N-methyl-2-pyrrolidone, 4,4′-diaminodiphenyl sulfone corresponding to 50 mol% and 3,3′-diaminodiphenyl sulfone corresponding to 50 mol% were dissolved, and 100 mol% was dissolved in this. The terephthalic acid dichloride corresponding to was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight.

  A part of the obtained polymer solution was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 7 minutes to obtain a self-holding film. The obtained film is peeled off from the stainless steel plate and fixed to a metal frame, immersed in a water bath containing 5% ethanol for 10 minutes, then washed in running water for 10 minutes, and further subjected to heat treatment at 280 ° C. for 1 minute. A 30 cm square aromatic polyamide film was obtained. The transparency was good, but the peelability was poor, and stepped unevenness and film tearing occurred. The physical properties of the obtained film were measured and are shown in Table 1.

(Comparative Example 2)
In dehydrated N-methyl-2-pyrrolidone, 4,4′-diaminodiphenyl sulfone corresponding to 50 mol% and 3,3′-diaminodiphenyl sulfone corresponding to 50 mol% were dissolved, and 100 mol% was dissolved in this. The terephthalic acid dichloride corresponding to is added, polymerized by stirring for 2 hours, neutralized with lithium carbonate, and then added with a fluorosurfactant (Recommon FN901 (manufactured by Clariant Japan)) in an amount of 100 parts by weight of polymer Was added to the polymer solution so as to be 2 parts by weight, and stirred at 60 ° C. for 10 hours. Thus, an aromatic polyamide solution having a polymer concentration of 10% by weight was obtained.

  A part of the obtained polymer solution was placed on a stainless steel plate having a mirror-like surface, and a uniform film was formed using a bar coater. This was dried at 120 ° C. for 7 minutes to obtain a self-holding film. The obtained film was peeled off from the stainless steel plate, fixed to a metal frame, washed in running water for 10 minutes, and further heat treated at 280 ° C. for 1 minute to obtain an aromatic polyamide film having a size of 30 cm square. Since the release agent was partially gel-like and remained undissolved in the polymer solution, when it was used as a film, the part was whitened and transparency was lowered. The physical properties of the obtained film were measured and are shown in Table 1.

(Comparative Example 3)
In Example 2, the amount of triphenyl phosphate added was 10 parts by weight with respect to 100 parts by weight of the polymer, and other than that, polymerization and film formation were performed in the same manner as in Example 2. Although the peelability was good, the film was whitened. The physical properties of the obtained film were measured and are shown in Table 1.

Claims (8)

It contains an aromatic polyamide and a release agent, the content of the release agent with respect to 100 parts by weight of the aromatic polyamide is 0.01 to 5 parts by weight, and the light transmittance for light having a wavelength of 450 nm is 80% or more and 100% or less. Is an aromatic polyamide film. The aromatic polyamide film according to claim 1, wherein the fluctuation of the retardation value in the film plane is within 10 nm. A structure in which the aromatic polyamide film includes a structural unit represented by chemical formula (I), (II), (III) or (IV), and is represented by chemical formula (I), (II), (III) and (IV) The aromatic polyamide film according to claim 1 or 2, wherein the following formulas (1) to (3) are satisfied when the molar fractions of the units are l, m, n, and o, respectively.
50 <l + m + n ≦ 100 (1)
0 ≦ l, m, n, o ≦ 100 (2)
0 ≦ o ≦ 50 (3)

R ¹ : a group having at least one 5-membered ring, 6-membered ring or 7-membered ring R ² : any aromatic group X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ³ : —CF ₃ , —CCl ₃ , —CBr ₃ , —OH, —F, —Cl, —OCH ₃ (however, structural units having these groups may be mixed in the molecule)
R ⁴ : any aromatic group

_{^{R 5: -SO 2 -, -}} O -, - CH 2 -, - C (CF 3) 2 - group selected from or _{-SO 2, -, - O -} , - CH 2 -, - C (CF 3 ₂ ) An aromatic group containing one or more groups selected from-.
R ^6: any aromatic group X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ^7: any aromatic radical R ^8: any aromatic group X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms The aromatic polyamide film includes a structural unit represented by chemical formula (V), (VI), (VII) or (VIII) and is represented by chemical formula (V), (VI), (VII) and (VIII) The aromatic polyamide film according to any one of claims 1 to 3, wherein the following formulas (4) to (6) are satisfied when the molar fraction of the structural unit is p, q, r, and s, respectively.
50 <p + q + r ≦ 100 (4)
0 ≦ p, q, r, s ≦ 100 (5)
0 ≦ s ≦ 50 (6)

X: hydrogen, halogen or a hydrocarbon group having 1 to 3 carbon atoms

R ⁹ : Arbitrary aromatic group R ¹⁰ : Arbitrary aromatic group The aromatic polyamide film according to any one of claims 1 to 4, wherein the release agent is a compound containing a fluorocarbon group in the molecule. The aromatic polyamide film according to any one of claims 1 to 5, wherein the release agent is a compound containing a phosphate group in the molecule. The image display element formed using the aromatic polyamide film in any one of Claims 1-6. A phase difference plate using the aromatic polyamide film according to claim 1.