JP2005146133A - Aromatic polyamide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aromatic polyamide film having excellent strength, elongation and clarity after long-term passage. <P>SOLUTION: This aromatic polyamide film comprises an aromatic polyamide and a light stabilizer, in which the content of the light stabilizer is 0.02-15 pts.wt. based on the aromatic polyamide resin of 100 pts. wt. The film shows a change in transmission b value of ≤4 before and after an exposure test according to JIS K 7350-2 under a condition of illumination of 100 mW/cm<SP>2</SP>, a temperature of 60°C, relative humidity of 50% RH and an irradiation time of 24 h. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aromatic polyamide film having light resistance. Specifically, it is an aromatic polyamide film that has excellent strength, elongation, and transparency, without deterioration of properties after a long period of time due to light from sunlight or fluorescent light, ultraviolet rays generated by other light emission, etc. Electrical applications such as electronic parts, adhesive tapes such as electrical insulating tapes and packing tapes, packaging applications such as confectionery bags, agricultural applications such as houses, cover display applications such as window glass and show windows, liquid crystal displays, plasma displays, etc. It can be suitably used as a display application.

  Usually, when used outdoors, polymer films will deteriorate over time when exposed to ultraviolet rays contained in sunlight for a long time, resulting in not only a decrease in strength and elongation, but also a significant increase in transparency and color tone. May decrease. Similarly, when used indoors, deterioration may occur over time when exposed to ultraviolet rays through windows or ultraviolet rays contained in fluorescent lamps. The decrease in strength and elongation makes it difficult to use for a long period of time in various applications, and the decrease in transparency and color tone is fatal because it leads to uneven color of the screen and the device in a transparent member such as a display device. Conventionally, polyester films have been used in the field of transparent materials such as display devices, but due to lack of heat resistance, they are not suitable for processing at high temperatures, and there are problems that they cannot be thinned due to insufficient rigidity. It has been considered effective to use a film. The aromatic polyamide film has excellent properties such as mechanical properties, electrical properties, dimensional stability, heat resistance, chemical resistance, and surface hardness. In particular, para-oriented aromatic polyamide films are more versatile because they have better heat resistance and rigidity than films obtained from other polymers.

For example, Patent Document 1 proposes a polyester film containing an ultraviolet absorber as a countermeasure against the degradation problem due to light of a polymer film. However, a polyester film is formed by a melt film forming method, whereas an aromatic polyamide film, particularly a para-oriented film, does not have a melting point, and therefore needs to be formed by a solution film forming method. It was generally difficult to adopt the method. In other words, since aromatic polyamide contains solvents and salts in addition to the polymer in the system, the use of the same method as the polyester film formed by the melt film-forming method causes the deterioration of dispersibility, etc. There was a problem that deterioration could not be suppressed.
JP 2003-1703 (2 pages, 2-6 paragraphs)

  The present invention is to solve the above problems and provide an aromatic polyamide film excellent in light resistance. That is, electrical applications such as electronic parts, adhesive tapes such as electrical insulation tape and packing tape, packaging applications such as confectionery bags, agricultural applications such as houses, cover applications such as window glass and show windows, liquid crystal displays, plasma displays, etc. In use as a display application, etc., it is to suppress discoloration or strength reduction of the film itself from ultraviolet rays emitted from sunlight or fluorescent lamps or other emitted light.

In order to achieve the above object, the present invention comprises an aromatic polyamide and a light stabilizer, the content of the light stabilizer is 0.02 to 15 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin, and In accordance with JIS K 7350-2 (Method B: Artificial light source undergrass exposure test), ultraviolet rays were subjected to an exposure test under the conditions of an illuminance of 100 mW / cm ² , a temperature of 60 ° C., a relative humidity of 50% RH, and an irradiation time of 24 hours. It is characterized by an aromatic polyamide film having a change in transmission b value before and after (Δb) of 4 or less.

  According to the present invention, an aromatic polyamide film excellent in light resistance can be obtained as described below.

  Hereinafter, examples of embodiments of the present invention will be described.

  In the present invention, the light stabilizer has an effect of suppressing deterioration of an aromatic polyamide film due to ultraviolet irradiation, and examples thereof include an ultraviolet absorber, a quencher, and HALS (Hindered Amine Light Stabilizer).

  An ultraviolet absorber is a substance that absorbs ultraviolet rays, etc., and releases the energy absorbed in the molecule by reducing the energy to heat, fluorescence, phosphorescence, etc., and is benzophenone, benzotriazole, cyanoacrylate, benzoate And the like.

  A quencher is a substance that returns a chromophore in the ground state (mainly unsaturated hydrocarbons and compounds thereof) to an original ground state after absorbing ultraviolet light and returning to the original ground state. Illustrated. Specifically, [2,2′-thiobis (4-t-octylphenolate)]-2-ethylhexylamine-nickel- (II), [2,2′-thiobis (4-t-octylphenolate) ] -N-butylamine-nickel- (II), nickel monoethyl 3,5-di-t-butyl-4-hydroxybenzyl phosphonate and the like.

  HALS is a light stabilizer that suppresses a photo-oxidation reaction by trapping alkyl radicals, peroxy radicals, and the like generated by ultraviolet irradiation, and examples thereof include compounds having a hindered piperidine skeleton. Specifically, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2, 4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}].

  The amount of the light stabilizer in the aromatic polyamide film of the present invention is preferably 0.02 to 15 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. When the amount is less than 0.02 parts by weight, the light resistance of the film is not sufficient, and physical properties may be deteriorated by receiving ultraviolet rays for a long time. On the other hand, if the amount is more than 15 parts by weight, the light resistance is not improved as compared with the added amount, which is not economical, and a phenomenon (bleed out) occurs in which the film is sprayed with other additives when the film is used. There is. From the standpoints of providing sufficient light resistance and economy, preventing light stabilizer bleed-out, and the like, it is more preferably 0.1 to 10 parts by weight, and 0.5 to 5 parts by weight. Further preferred. The content of the light stabilizer in the film can confirm the weight ratio with the polymer by confirming the weight loss due to heat of the light stabilizer in the film using TGA. At this time, there may be a difference between the amount of the light stabilizer added to the aromatic polyamide solution and the amount of the light stabilizer contained in the aromatic polyamide film. It is thought that it was because. Even if you don't know the type of added light stabilizer, you can identify the light stabilizer and film by selecting qualitative analysis methods such as NMR, IR, ICP, GC-MS, and quantitative analysis methods such as TGA. The content of the light stabilizer inside can be confirmed.

Furthermore, the aromatic polyamide film of the present invention has an illuminance of 100 mW / cm ² , a temperature of 60 ° C., a relative humidity of 50% RH, and an irradiation time of 24 hours in accordance with JIS K 7350-2 (Method B: artificial light source undergrass exposure test). The change in the transmission b value before and after the exposure test was performed under the conditions of 4 or less (hereinafter, this exposure test is referred to as a light resistance test). Here, the change in the transmission b value before and after the light resistance test = the transmission b value after the light resistance test−the transmission b value before the light resistance test, which is expressed as Δb. When the Δb value exceeds 4, deterioration of the film such as strength and elongation may increase, and when used as a transparent member, discoloration may be conspicuous and give a low-quality impression.

  In addition, b value here is a value defined by Hunter Lab color system, for example, can be measured using a spectroscopic color difference meter SE-2000 type (manufactured by Nippon Denshoku Industries Co., Ltd.). .

In addition, the above light resistance test uses, for example, an ultraviolet degradation acceleration tester iSuper UV Tester XER-W75 (manufactured by Iwasaki Electric Co., Ltd.), an illuminance of 100 mW / cm ² , a temperature of 60 ° C., and a relative humidity of 50%. It can be carried out by irradiation for 24 hours under the condition of RH.

  Of the above-described light stabilizers, UV absorbers are particularly preferable. This is because when used as a transparent member for display applications such as window glass and show windows, display applications such as liquid crystal displays and plasma displays, from ultraviolet rays emitted from sunlight or fluorescent lamps or other emitted light, This is because there is an effect of suppressing the characteristic change of the film itself, that is, yellowing and strength reduction, and the effect of maintaining the function of protecting the contents for a long time. For example, a liquid crystal display member that is excellent in the ability to absorb ultraviolet light having a wavelength of 380 nm or less from the viewpoint of preventing deterioration of the liquid crystal and that has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of good liquid crystal display properties is preferably used. . In particular, the transmittance at a wavelength of 380 nm is preferably 60% or less, more preferably 40% or less, and still more preferably 20% or less. In order to keep the transmittance of the transparent film at 380 nm at 60% or less, it is effective to use an aromatic polyamide containing an ultraviolet absorber.

  Examples of the ultraviolet absorber include benzotriazole compounds, benzophenone compounds, benzoate compounds, cyanoacrylate compounds, salicylic acid ester compounds, oxybenzophenone compounds, triazine compounds, and inorganic compounds. Is not limited to these.

  Here, as the benzotriazole compounds, 2- (2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-) Methylphenyl) -5-carboxylic acid butyl ester benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -5,6-dichlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -5-ethylsulfonebenzotriazole, 2- (2'-hydroxy-5'-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-aminophenyl) benzotriazole, 2- (2'-hydroxy) -3 ', 5'-dimethylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-dimethylphenyl) -5-methoxybenzotriazole, 2- (2'-methyl-4'-hydroxyphenyl) ) Benzotriazole, 2- (2'-stearyloxy-3 ', 5'-dimethylphenyl) -5-methylbenzotriazole, 2- (2'-hydroxy-5-carboxylic acid phenyl) benzotriazole ethyl ester, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-methyl-5'-t-butylphenyl) -5 Chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, -(2'-hydroxy-5'-methoxyphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'- Hydroxy-5'-cyclohexylphenyl) benzotriazole, 2- (2'-hydroxy-4 ', 5'-dimethylphenyl) -5-carboxylic acid benzotriazole, 2- (2'-hydroxy-5-methylphenyl)- 5-carboxylic acid butyl ester benzotriazole, 2- (2'-hydroxy-4 ', 5'-dichlorophenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-dimethylphenyl) -5 Ethylsulfobenzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- (2'- Droxy-5'-methoxyphenyl) -5-methylbenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -5-carboxylic acid ester benzotriazole, 2- (2'-acetoxy-methylphenyl) benzo A triazole etc. can be illustrated.

  Examples of the benzophenone compounds include 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2, 2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-benzoyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonebenzophenone, 2, 2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, bis- (2-methoxy-4-hydroxy-5-benzoyl) Phenyl) meta It can be exemplified, and the like.

  Examples of benzoate compounds include phenyl salicylate, 4-t-butylphenyl salicylate, 2,5-t-butyl-4-hydroxybenzoic acid n-hexadecyl ester, 2,4-di-t-butylphenyl -3 ′, 5′-di-t-butyl-4′-hydroxybenzoate and the like can be exemplified.

  An example of the cyanoacrylate compound is ethyl-2-cyano-3,3-diphenylacrylate. Examples of salicylic acid ester compounds include phenyl salicylate and 4-t-butylphenyl salicylate. Examples of oxybenzophenone compounds include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone. Examples of triazine compounds include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol.

  Examples of inorganic compounds include titanium oxide, zinc oxide, cerium oxide, iron oxide, and barium sulfate.

  In the present invention, it is preferable to use either benzotriazole type or benzophenone type among the above specific examples, and specifically, 2- (2H-benzotriazol-2-yl) -4,6-bis. It is preferable to use (1-methyl-1-phenylethyl) phenol and bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane.

  The aromatic polyamide film in the present invention preferably has a light transmittance at a light wavelength of 450 nm to 700 nm before the light resistance test of 80% or more and 100% or less. More preferably, the light transmittance is 85% or more and 100% or less, and further preferably 90% or more and 100% or less. If the light transmittance at a light wavelength of 450 nm to 700 nm is less than 80%, it becomes difficult to use the aromatic polyamide film as various transparent members.

  Moreover, the aromatic polyamide film in the present invention can achieve both excellent mechanical properties such as high Young's modulus, surface hardness, glass transition temperature, and high transparency when an aromatic polyamide film having the structural units shown below is used. Therefore, it is 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 (V). 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.

  In the aromatic polyamide film in the present invention, it is important that the change in the transmission b value before and after the light resistance test is 4 or less, and when it is 3 or less, there is little decrease in strength of the film after the light resistance test. Preferably, when it exceeds 4, yellowing of the film and strength reduction are large, and long-term use becomes difficult. In order to keep the change in the transmission b value before and after the light resistance test at 4 or less, to prevent the deterioration of the film and to suppress the strength reduction, uniformly disperse the light stabilizer, particularly the ultraviolet absorber, in the aromatic polyamide. It becomes important. By uniformly dispersing, it is possible to suppress the deterioration of the polymer due to light and to suppress the change in the transmission b value before and after the light resistance test to 4 or less. As a result, it is possible to suppress the deterioration of various physical properties such as film strength and elongation. be able to. Methods for adding a light stabilizer include a method of adding a diamine and acid dichloride to a reaction vessel before aromatic polyamide polymerization, a method of adding to a solution after polymerization, and a method of providing a coating layer containing a light stabilizer. Can be mentioned. However, when a light stabilizer is added to the aromatic polyamide solution after polymerization, the viscosity of the solution is high, so that it is difficult to disperse uniformly. Therefore, a method of adding before polymerization or a method of providing a coating layer is preferable.

  In order to improve the dispersibility of the light stabilizer, it is preferable to adjust the pH of the aromatic polyamide solution to 6 to 9 because the dispersibility of the light stabilizer in the solution is improved. In an acidic region of less than 6 or a basic region of more than 9, the light stabilizer may be decomposed when heat is applied during film formation.

  The method for adding the light stabilizer in the present invention includes sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, N-dimethylacetamide, N, Acetamide solvents such as N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- or p-cresol, halogenated phenol, catechol, etc. It is preferable to dissolve the light stabilizer in a phenolic solvent or an organic solvent such as hexamethylphosphoramide or γ-butyrolactone and then add it to the reaction vessel before polymerization. In forming the coating layer, it is preferable to mix a resin component such as an acrylic resin as a binder with the ultraviolet absorber. That is, the resin component and the UV absorber are dissolved in an organic solvent capable of dissolving the resin component and the light stabilizer, water, a mixture of two or more organic solvents, or an organic solvent / water mixture to form a coating solution. Are preferably used. Of course, the resin component and the ultraviolet absorber separately dissolved or dispersed in an organic solvent, water, an organic solvent mixed solution, or an organic solvent / water mixed solution may be arbitrarily mixed and used.

  Although the example of the manufacturing method of the aromatic polyamide film used preferably in this invention 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, terphenyl dicarbonyl chloride, and the like. Most preferably, terephthalic acid dichloride, 2chloro. 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. However, when an inorganic neutralizer is used, there is a problem that it is difficult to react 100% with hydrogen chloride. When an organic neutralizer is used, the hydrochloride is decomposed by heat and returns to the neutralizer and hydrogen chloride. There is a problem. Therefore, the neutralization method neutralizes 90 to 98% of hydrogen chloride using an inorganic neutralizer, and then neutralizes the remaining hydrogen chloride using an organic neutralizer, Finally, it is preferable to adjust the pH to 6-9.

  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 film of the present invention include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide such as N, N-dimethylformamide and N, N-diethylformamide. Solvents, N, N-dimethylacetamide, N, N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and other pyrrolidone solvents, phenol, o-, m- Alternatively, phenolic solvents such as p-cresol, xylenol, halogenated phenol, catechol, hexamethylphosphoramide, γ-butyrolactone, etc. can be mentioned, and these are preferably used alone or as a mixture, but more preferably xylene The The use of aromatic hydrocarbons such as ene are also possible. Furthermore, for the purpose of accelerating the dissolution of the polymer, 50 parts by weight or less of alkali metal or alkaline earth metal salt can be added to the solvent with respect to 100 parts by weight of the polymer.

The aromatic polyamide film of the present invention may contain 10 parts by weight or less of an inorganic or organic additive with respect to 100 parts by weight of the polymer for the purpose of surface formation and processability improvement. 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.

  As the film-forming stock solution, the neutralized polymer solution may be used as it is, or a polymer once isolated and then redissolved in a solvent may be used. As the solvent, organic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide are preferable because of easy handling, but strongly acidic such as concentrated sulfuric acid, concentrated nitric acid, polyphosphoric acid and the like. A solvent may be used. The polymer concentration in the film-forming stock solution is preferably about 2 to 50% by weight.

  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 and dried until the thin film has self-holding property. The film after the dry process is peeled off from the support and introduced into the wet process, desalted, desolvated, etc., and further stretched, dried and heat treated 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. In addition, at 500 ° C. or higher, the film may be colored. The aromatic polyamide film of the present invention is not limited to a single-layer film, and may be a laminated film, or various undercoats for the purpose of imparting gas barrier properties, improving solvent resistance, improving surface hardness, etc. It may be a composite film subjected to surface treatment.

  Hereinafter, the present invention will be described by way of examples. The characteristics were measured and evaluated by the following methods.

(1) Light resistance test Using an ultraviolet degradation acceleration tester, iSuperxenon Tester XER-W75 (Iwasaki Electric Co., Ltd.), according to JIS K 7350-2 (Method B: Artificial light source undergrass exposure test) The forced ultraviolet irradiation test was conducted under the conditions.

"UV irradiation conditions"
Light source: Xenon lamp Illuminance: 100 mW / cm ²
Temperature: 60 ° C
Relative humidity: 50% RH
Irradiation time: 24 hours (2) Transmission b value Using a spectroscopic color difference meter SE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), the transmission method according to JIS-K-7105 (established March 1, 1981) The film before and after the light resistance test was measured.

Δb (change in transmission b value before and after light resistance test) = transmission b value after light resistance test−transmission b value before light resistance test (3) Light transmittance UV measuring instrument U-3410 (manufactured by Hitachi Keiki Co., Ltd.) The transmittance corresponding to the light of each wavelength was measured and evaluated by the following method.

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: Permeation (4) Breaking strength and breaking strength reduction rate Using Robot Tensilon RTA100 (Orientec), measured at a temperature of 23 ° C. and a relative humidity of 65%, and evaluated by the following method. did. However, the test piece was a sample having a width of 10 mm and a length of 50 mm. The tensile speed is 300 mm / min. However, the point where the load passed 1 N after the start of the test was taken as the origin of elongation. The breaking strength reduction rate was obtained from the following formula and evaluated.

Breaking strength reduction rate (%) = ((breaking strength before light resistance test−breaking strength after light resistance test) / breaking strength before light resistance test) × 100
(Evaluation criteria)
○: Breaking strength reduction rate ≦ 30%
Δ: 30% <break strength reduction rate ≦ 50%
×: 50% <break strength reduction rate (5) Long-term cut property of 380 nm light Using the above UV measuring device U-3410 (manufactured by Hitachi Keiki Co., Ltd.), the transmittance was measured under the same conditions. evaluated.

○: Satisfies criteria (a) and (b) Δ: Satisfies only criterion (b) ×: Does not satisfy both criteria (a) and (b) Criterion (a) = 380 nm transmittance before light resistance test ≦ 60%
Criteria (b) = 380 nm transmittance before light resistance test−380 nm transmittance after light resistance test ≦ 20%
(6) Visual color The color of the film after the light resistance test was visually confirmed.

(Circle): Colorless (triangle | delta): Yellow x: Dark yellow or cloudiness (7) Measuring method of pH It measured by attaching a polymer solution to pH test paper UNIV test paper (made by Toyo Filter Paper Co., Ltd.).

(Example 1)
Dehydrated N-methyl-2-pyrrolidone and benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.), 2,2′-bis (trifluoromethyl)-equivalent to 100 mol% 4,4′-Diaminobiphenyl was dissolved, and 2-chloroterephthalic acid chloride corresponding to 100 mol% was added thereto, and polymerization was carried out by stirring for 2 hours. Thereafter, neutralization was performed using 96.5 mol% lithium carbonate and 5.5 mol% diethanolamine, and the pH was adjusted to 8 using 13 mol% triethanolamine. The resulting solution was an aromatic polyamide solution having a polymer concentration of 10% by weight and containing 2 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the aromatic polyamide.

  The obtained UV polyamide-containing aromatic polyamide solution having a polymer concentration of 10% by weight was cast on a support with a bar coater, dried in an oven at 120 ° C. for 7 minutes to evaporate the solvent, and self-supporting properties were exhibited. The polymer sheet was peeled from the support. Subsequently, the peeled film was passed into the water tank for 5 minutes, and the remaining solvent and the inorganic salt produced by neutralization were extracted with water. Thereafter, heat treatment was performed for 1 minute while keeping the width constant in an oven at a temperature of 280 ° C. to obtain an aromatic polyamide film having a thickness of 10 μm, which is Example 1 of the present invention.

  From the TGA of the obtained film, the content of the light stabilizer was 1.98 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The transmittance before the light resistance test is shown in FIG. The transmittance before the light resistance test was 80% or more at 450 to 700 nm. Further, the film after the light resistance test was less deteriorated and excellent in light resistance. Also, it has high transparency, and when used as a transparent member, it has a function of protecting contents from ultraviolet rays. The results are shown in Table 1.

(Example 2)
Dehydrated N-methyl-2-pyrrolidone and HALS (“TINUVIN 144” manufactured by Ciba Specialty Chemicals Co., Ltd.), 2,2′-bis (trifluoromethyl) -4,4′- equivalent to 100 mol% Diaminobiphenyl was dissolved, 2-chloroterephthalic acid chloride corresponding to 100 mol% was added thereto, and polymerization was carried out by stirring for 2 hours. Thereafter, neutralization was performed using 96.5 mol% lithium carbonate and 5.5 mol% diethanolamine, and the pH was adjusted to 8 using 13 mol% triethanolamine. The obtained solution was an aromatic polyamide solution having a polymer concentration of 10% by weight and containing 2 parts by weight of a light stabilizer with respect to 100 parts by weight of the aromatic polyamide resin.

  This polymer solution was made into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 12 μm. The obtained film was excellent in transparency.

  From the TGA of the obtained film, the content of the light stabilizer was 1.93 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The film after the light resistance test was less deteriorated and excellent in light resistance. However, since it does not contain an ultraviolet absorber, it has inferior long-term ultraviolet cut ability. The results are shown in Table 1.

(Example 3)
Except for changing the amount of the UV absorber, the polymer concentration was 10% by weight, and the benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.) was used in the same manner as in Example 1. An aromatic polyamide solution containing 11 parts by weight with respect to parts was obtained.

  This polymer solution was made into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 13 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 10.97 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The obtained film contained a large amount of the ultraviolet absorber, and thus the light resistance was slightly deteriorated compared to Example 1, but was within the practical range. The results are shown in Table 1.

Example 4
Except for changing the amount of the UV absorber, the polymer concentration was 10% by weight and the benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.) was used in the same manner as in Example 1. An aromatic polyamide solution containing 0.07 parts by weight with respect to parts was obtained.

  This polymer solution was made into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 11 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 0.05 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. Since the obtained film had a small content of the ultraviolet absorber, its light resistance was slightly deteriorated compared to Example 1, but it was within the practical range. The results are shown in Table 1.

(Example 5)
Dehydrated N-methyl-2-pyrrolidone, benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.), 2-chloroparaphenylenediamine equivalent to 85 mol%, equivalent to 15 mol% 4,4′-diaminodiphenyl ether was dissolved, 2-chloroterephthalic acid dichloride corresponding to 100 mol% was added thereto, and polymerization was carried out by stirring for 2 hours. Thereafter, neutralization was performed using 96.5 mol% lithium carbonate and 5.5 m% diethanolamine, and the pH was adjusted to 8 using 13 mol% triethanolamine. The resulting solution was an aromatic polyamide solution having a polymer concentration of 10% by weight and containing 2 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the aromatic polyamide.

  This polymer solution was formed into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 15 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 1.98 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The resulting film was transparent but slightly colored yellow. The film after the light resistance test was less deteriorated and excellent in light resistance. The results are shown in Table 1.

(Comparative Example 1)
2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl corresponding to 100 mol% is dissolved in dehydrated N-methyl-2-pyrrolidone, and 2-mol corresponding to 100 mol% is dissolved therein. Chlorterephthalic acid chloride was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to polymerize the polymer. A benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to this polymer solution and stirred for 1 hour. The polymer concentration was 10% by weight and the UV absorber was 100% by weight of aromatic polyamide. An aromatic polyamide solution containing 0.07 parts by weight with respect to parts was obtained.

  This polymer solution was formed into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 11 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 0.05 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The obtained film is inferior in light resistance because an ultraviolet absorber is added after polymerization of the polymer and the pH is not in the range of 6 to 9, so that the ultraviolet absorber cannot exhibit its original physical properties. It was. The results are shown in Table 1.

(Comparative Example 2)
Except for changing the amount of the UV absorber, the polymer concentration was 10% by weight, and the benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.) was used in the same manner as in Example 1. An aromatic polyamide solution containing 17 parts by weight with respect to parts was obtained.

  This polymer solution was formed into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 11 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 16.97 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. Since the obtained film contained too much ultraviolet absorber, the ultraviolet absorber slightly bleeded out after the light resistance test, and the film became cloudy. The results are shown in Table 1.

(Comparative Example 3)
Except for changing the amount of the UV absorber, the polymer concentration was 10% by weight and the benzotriazole UV absorber (“TINUVIN234” manufactured by Ciba Specialty Chemicals Co., Ltd.) was used in the same manner as in Example 1. An aromatic polyamide solution containing 0.01 parts by weight with respect to parts was obtained.

  This polymer solution was formed into a film in the same manner as in Example 1 to obtain an aromatic polyamide film having a thickness of 11 μm.

  From the TGA of the obtained film, the content of the light stabilizer was 0.009 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin. The obtained film was inferior in light resistance since the content of the ultraviolet absorber was small. The results are shown in Table 1.

  The present invention relates to an aromatic polyamide film having excellent strength, elongation, transparency, and color tone even after long-term aging, and includes packaging materials, adhesive tapes, magnetic tapes, display devices such as liquid crystal displays and plasma displays, and decorations. Although it can be suitably used as a transparent member such as a display material such as a printed material or a window material, its application range is not limited thereto.

2 is a schematic graph showing the transmittance of a film before a light resistance test in Example 1. FIG.

Claims (4)

An aromatic polyamide and a light stabilizer, the light stabilizer content is 0.02 to 15 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin, and JIS K 7350-2 (Method B: artificial light source) According to the undergrass exposure test), the fragrance has a change in transmission b value of 4 or less before and after the exposure test was performed under the conditions of an illuminance of 100 mW / cm ² , a temperature of 60 ° C., a relative humidity of 50% RH, and an irradiation time of 24 hours. Group polyamide film. The aromatic polyamide film according to claim 1, wherein the light stabilizer is an ultraviolet absorber. The aromatic polyamide film according to claim 1 or 2, wherein the light transmittance for all light having a wavelength of 450 to 700 nm before irradiation with ultraviolet rays is from 80% to 100%. Mole fraction of structural units containing structural units represented by chemical formula (I), (II), (III) or (IV) and represented by chemical formulas (I), (II), (III) and (IV) The aromatic polyamide film according to any one of claims 1 to 3, wherein the following formulas (1) to (3) are satisfied when the rates 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

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