JP2005313342A - Conductive film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive film having excellent transparency and conductivity and excellent in solvent resistance. <P>SOLUTION: The conductive film is constituted by laminating a base material film, a transparent conductive coating film layer and a protective layer with a thickness of 3-50 nm comprising a reaction product of a metal alkoxide in this order. The total light transmissivity thereof is 60% or above and the surface resistance on the protective layer side of the conductive film is 10-1×10<SP>5</SP>Ω/square. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive film, and more particularly to a transparent conductive film suitably used as a transparent electrode such as a liquid crystal display (LCD) transparent touch panel, an organic electroluminescence element, an inorganic electroluminescence lamp, or an electromagnetic shielding material. .

Conventionally, a transparent conductive film is suitably used as a transparent electrode such as a liquid crystal display or a transparent touch panel, or as an electromagnetic shielding material. These transparent conductive films include indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), and In ₂ O on at least one surface of a transparent film surface such as polyethylene terephthalate (PET) or triacetyl cellulose (TAC). It is well known that a mixed sintered body (ITO) of ₃ and SnO ₂ is provided by a dry process such as vacuum deposition, sputtering, or ion plating.

  These transparent conductive films have web-like continuous processing and punching processes, and are used and stored in a bent state during surface processing. During this time, cracks may occur and the surface resistance may increase.

  On the other hand, the transparent conductive coating layer formed by wet-coating a conductive polymer on a transparent substrate film has flexibility in the film itself and does not cause problems such as cracks. In addition, the method of obtaining a transparent conductive film by wet application of a conductive polymer has advantages that the manufacturing cost is relatively low because the dry process is not used, the coating speed is generally high, and the productivity is excellent. The transparent conductive films obtained by wet coating of such conductive polymers are polythiophene, polyaniline, polypyrrole, etc. that have been generally used so far because high conductivity cannot be obtained in the initial stage of development. Use has been limited to antistatic applications or the like, and the hue of the conductive coating layer itself has been a problem. However, these problems have recently been improved by improving the production method. For example, a conductive polymer (Patent Document 1) comprising a poly (3,4-dialkoxythiophene) obtained by oxidative polymerization of 3,4-dialkoxythiophene in the presence of a polyanion and a polyanion is a recent production method. (Patent Document 2 and Patent Document 3) improve the surface resistance while maintaining a high light transmittance.

  However, in the case of a transparent conductive film using these conductive polymers as a transparent conductive coating layer, solvent resistance and water resistance on the film surface in subsequent processing steps have been problems. In order to solve this problem, a method of forming a coating film by adding a polymer material as a binder component to such a conductive polymer, coating film strength (Patent Document 4) and water resistance using a silane coupling agent Although a method for improving (Patent Document 5) has been proposed, improvement in solvent resistance, particularly solvent resistance to alcohols, esters and the like has not been sufficient.

Japanese Patent Laid-Open No. 1-313521 JP 2002-193972 A JP 2003-286336 A JP-A-10-88030 JP 2002-60763 A

  An object of the present invention is to solve the above-described problems of the prior art, that is, to provide a transparent conductive film having excellent transparency and conductivity and excellent solvent resistance.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that when a protective layer made of a specific material is formed with a specific thickness on a transparent conductive coating layer using a conductive polymer, The present inventors have found that the solvent resistance can be improved without significantly affecting the resistance value, and have reached the present invention.

Thus, according to the present invention, an object of the present invention is a conductive film in which a protective film having a thickness of 3 to 50 nm comprising a base film, a transparent conductive coating layer and a reaction product of a metal alkoxide is laminated in this order. And it is achieved by a conductive film having a total light transmittance of 60% or more and a surface resistance on the protective layer side of the conductive film in the range of 10 to 1 × 10 ⁵ Ω / □.

（ここで、式中、Ｒ^１およびＲ^２は相互に独立して水素またはＣ１−４のアルキル基を表すか、あるいは一緒になって任意に置換されてもよいＣ１−４のアルキレン基を表す）で表される繰り返し単位からなるポリカチオン状のポリチオフェンと、ポリアニオンとの導電性高分子からなること、該透明導電塗膜層が、該導電性高分子とテトラアルコキシシランおよびアルコキシ基以外の反応性の官能基を有するトリアルコキシシランからなる群より選ばれた少なくとも一種の反応生成物とからなること、該透明導電塗膜層が、該導電性高分子とグリシドキシ基を有したトリアルコキシシランの反応生成物とからなること、該保護層がアルコキシシランの反応生成物からなること、該透明導電塗膜層の表面抵抗が１０〜１×１０^５Ω／□の範囲にあることの少なくともいずれか一つを具備する導電性フィルムも提供される。 Further, according to the present invention, as a preferred embodiment of the conductive film of the present invention, the transparent conductive coating layer has the following general formula:

(Wherein, R ¹ and R ² each independently represent hydrogen or a C 1-4 alkyl group, or a C 1-4 alkylene group which may be optionally substituted together) ) A polycationic polythiophene composed of a repeating unit represented by formula (II) and a polyanion and a conductive polymer, and the transparent conductive coating layer reacts with the conductive polymer other than tetraalkoxysilane and alkoxy groups. Comprising at least one reaction product selected from the group consisting of trialkoxysilane having a functional functional group, and the transparent conductive coating layer of trialkoxysilane having a glycidoxy group with the conductive polymer. be made of the reaction product, that the protective layer comprises a reaction product of the alkoxysilane, the surface resistance of the transparent conductive coating layer is 10~1 × 10 ⁵ Ω / □ range of Conductive films comprising at least one of the in also provided.

  Furthermore, according to the present invention, a transparent conductive coating layer is formed on one side of the base film, and a protective layer having a thickness of 3 to 50 nm made of a reaction product of a metal alkoxide is further formed thereon. Also provided is a method for producing a featured conductive film.

  The transparent conductive film of the present invention requires that a protective film composed of a base film, a transparent conductive coating layer and a reaction product of a metal alkoxide is laminated in this order. When the transparent conductive coating layer is located on the surface of the conductive film, the effect of improving the solvent resistance by the protective layer cannot be exhibited.

  The transparent conductive film of the present invention needs to have a total light transmittance of 60% or more. When the total light transmittance is less than the lower limit, it is difficult to obtain sufficient transparency when used as a transparent electrode such as a liquid crystal display or a transparent touch panel or an electromagnetic shielding material. A preferable total light transmittance is 65% or more, and further 70% or more. Such a total light transmittance can be suitably adjusted by selection of the below-mentioned base film, transparent conductive coating layer, and protective layer.

Furthermore, the surface resistance on the protective layer side of the conductive film needs to be in the range of 10 to 1 × 10 ⁵ Ω / □. If the surface resistance on the protective layer side of the conductive film exceeds the upper limit, it may not function as an electrode when used as a transparent electrode or electromagnetic shielding material for liquid crystal displays, transparent touch panels, etc., or sufficient electromagnetic shielding characteristics will be obtained. I can't. On the other hand, making it below the lower limit tends to destabilize the manufacturing process. A preferable surface resistance is 10 to 1 × 10 ⁴ Ω / □, and further 10 to 5 × 10 ³ Ω / □. From this viewpoint, the surface resistance of the transparent conductive coating layer on which the protective layer is formed is also 10 to 1 × 10 ⁵ Ω / □, more preferably 10 to 1 × 10 ⁴ Ω / □, particularly 10 to 5 × 10 ³ Ω / □. It is preferable that it is in the range of □.

  According to the present invention, a protective layer made of a specific material is formed with a specific thickness on a transparent conductive coating layer using a conductive polymer, and as a result, the surface resistance value is significantly affected. Therefore, the solvent resistance can be improved, and a transparent conductive film having excellent transparency, conductivity and solvent resistance can be provided with high productivity. Moreover, the transparent conductive film produced by this method can be suitably used as a transparent electrode such as a liquid crystal display (LCD) transparent touch panel, an organic electroluminescence element, an inorganic electroluminescence lamp, or an electromagnetic shielding material.

  First, the conductive film of the present invention will be described with reference to FIG. FIG. 1 shows a cross-sectional view of the conductive film of the present invention, that is, an example of a layer structure. In FIG. 1, reference numeral 1 denotes a base film, reference numeral 2 denotes a transparent conductive coating layer, and reference numeral 3 denotes a protective layer. As can be seen from FIG. 1, the conductive film of the present invention is one in which a transparent conductive coating layer is first laminated on one side of a base film, and a protective layer is further laminated on the transparent conductive coating layer. If it has such a configuration, it is easily understood that other functional layers such as an antireflection layer may be further formed as long as the object of the present invention is not impaired. I will.

で表される繰り返し単位からなるからなるカチオン状のポリチオフェン（以下、“ポリ（３，４−ジ置換チオフェン）”と称することがある）と、ポリアニオンとを含んでなる導電性高分子（ａ）からなることが好ましい。すなわち、この導電性高分子（ａ）はポリ（３，４−ジ置換チオフェン）とポリアニオンとの複合化合物である。 Hereinafter, each layer forming the conductive film of the present invention will be described in more detail.
The transparent conductive coating layer in the present invention is not particularly limited as long as the surface resistance can be lowered and also has transparency. For example, the following general formula as described in JP-A-2002-60763 is used.

A conductive polymer (a) comprising a cationic polythiophene comprising a repeating unit represented by the formula (hereinafter sometimes referred to as “poly (3,4-disubstituted thiophene)”) and a polyanion. Preferably it consists of. That is, the conductive polymer (a) is a composite compound of poly (3,4-disubstituted thiophene) and a polyanion.

R ¹ and R ² of the poly (3,4-disubstituted thiophene) constituting the conductive polymer (a) each independently represent hydrogen or a C 1-4 alkyl group, or together It is an optionally substituted C1-12 alkylene group. Representative examples of the optionally substituted C1-12 alkylene group formed by combining R ¹ and R ² are 1,2-alkylene groups (for example, 1,2-cyclohexylene and 2 , 3-butylene, etc.). Suitable examples of the C1-12 alkylene group formed by combining R ¹ and R ² are methylene, 1,2-ethylene and 1,3-propylene groups, Is preferred. Specific examples include a methylene group which may be alkyl-substituted, a 1,2-ethylene group which may be substituted with a C1-12 alkyl group or a phenyl group, and a 1,3-propylene group.

  Examples of the polyanion constituting the conductive polymer (a) include polymeric carboxylic acids (for example, polyacrylic acid, polymethacrylic acid, polymaleic acid), and polymeric sulfonic acids (for example, polyethylene sulfonic acid, polyvinyl sulfonic acid). Etc. These polymeric carboxylic acids and sulfonic acids may be copolymers of vinyl carboxylic acids and vinyl sulfonic acids with other polymerizable low molecular compounds such as acrylates and styrene. Among these polyanions, those having polystyrene sulfonic acid and all or part of which are metal salts are preferably used.

  The coating composition for forming the transparent conductive coating layer in the present invention uses as a main component a liquid in which the above-described conductive polymer is dispersed in water, but if necessary, polyester, polyacryl, polyurethane, polyvinyl acetate, A suitable organic polymer material such as polyvinyl butyral can be added as a binder.

  In addition, the coating composition for forming such a transparent conductive coating layer is water for the purpose of dissolving the binder, improving the wettability to the transparent substrate film, or adjusting the solid content concentration, if necessary. A suitable solvent that is compatible with can be added. Examples of the solvent to be added include alcohols (methanol, ethanol, propanol, isopropanol, etc.), amides (formamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methyl Propionamide) and the like are preferably used.

  Moreover, you may add an alkoxysilane further to the coating composition which forms this transparent conductive coating layer for the purpose of improving the coating-film intensity | strength obtained as needed. This alkoxysilane is present in the transparent conductive coating layer in the form of a reaction product obtained by hydrolysis and subsequent condensation reaction. Examples of alkoxysilanes include methyltriacetoxysilane, dimethyldiacetoxysilane, trimethylacetoxysilane, tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetraisobutoxysilane, methyltriethoxysilane, dimethyldi Examples include ethoxysilane, trimethylethoxysilane, and phenyltriethoxysilane. A catalyst is required to efficiently proceed the hydrolysis / condensation of the alkoxysilane. An acidic catalyst or a basic catalyst can be used as the catalyst. As the acidic catalyst, inorganic acids such as acetic acid, hydrochloric acid and nitric acid, and organic acids such as acetic acid, citric acid, propionic acid, oxalic acid and p-toluenesulfonic acid are suitable. As the basic catalyst, organic amine compounds such as ammonia, triethylamine and tripropylamine, and alkali metal compounds such as sodium methoxide, potassium methoxide, potassium ethoxide, sodium hydroxide and potassium hydroxide are suitable.

  In addition, a small amount of a surfactant may be added to the coating composition for forming a transparent conductive coating layer in the present invention for the purpose of improving the wettability with respect to the substrate. Preferred surfactants include nonionic surfactants (eg, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, sorbitan fatty acid ester, etc.), and fluorosurfactants (eg, fluoroalkylcarboxylates, Fluoroalkylbenzene sulfonate, perfluoroalkyl quaternary ammonium, perfluoroalkyl polyoxyethylene ethanol, etc.).

  The protective layer in the present invention is formed from a condensation reaction product after hydrolysis of the metal alkoxide. The metal alkoxide preferably used is a compound represented by the following general formula.

ここで、上記一般式中の、Ｒ^３およびＲ^４は、それぞれメチル基、エチル基、ノルマルプロピル基、イソプロピル基、ノルマルブチル基、イソブチル基、アセトキシ基などが例示でき、Ｍは金属元素を表し、好ましくはＡｌ、Ｓｉ、Ｔｉ、Ｚｒであり、中でも特にＳｉが好ましい。また、上記式におけるｍは金属元素Ｍの価数を示し、ｎは金属元素Ｍに付加するアルコキシ基の数を示し、ｎはｍと同じかそれよりも小さい数である。これら化合物の中でも加水分解可能な物質が好ましく、好ましい金属アルコキシドとしては、メチルトリアセトキシシラン、ジメチルジアセトキシシラン、トリメチルアセトキシシラン、テトラアセトキシシラン、テトラメトキシシラン、テトラエトキシシラン、テトライソプロポキシシラン、テトライソブトキシシラン、メチルトリエトキシシラン、ジメチルジエトキシシラン、トリメチルエトキシシラン、フェニルトリエトキシシラン、γ―グリシドキシトリメトキシシランなどがあげられる。上記アルコキシシランの加水分解／縮合を効率よく進行させるためには触媒が必要となる。好適に用いられる触媒としては、上述の透明導電塗膜層で説明したものと同様なものが挙げられる。

Here, R ³ and R ⁴ in the above general formula can be exemplified by a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, an acetoxy group, etc., and M represents a metal element. Of these, Al, Si, Ti, and Zr are preferable, and Si is particularly preferable. In the above formula, m represents the valence of the metal element M, n represents the number of alkoxy groups added to the metal element M, and n is the same as or smaller than m. Of these compounds, hydrolyzable substances are preferred, and preferred metal alkoxides include methyltriacetoxysilane, dimethyldiacetoxysilane, trimethylacetoxysilane, tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra Examples include isobutoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, phenyltriethoxysilane, and γ-glycidoxytrimethoxysilane. A catalyst is required to efficiently proceed the hydrolysis / condensation of the alkoxysilane. As a catalyst used suitably, the thing similar to what was demonstrated by the above-mentioned transparent conductive coating layer is mentioned.

  Solvents used in the coating composition for forming such a protective layer include aromatic hydrocarbons such as benzene, toluene, and xylene, esters such as ethyl acetate, butyl acetate, and isobutyl acetate, methyl ethyl ketone, and ketones such as methyl isobutyl ketone, Examples include ethers such as tetrahydrofuran, alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol, and propylene glycol. Of these, alcohols, ketones, ethers, and esters are preferable.

  Although the reason why the surface resistance value is not greatly affected even if such a protective layer is formed on the transparent conductive coating layer is not clear, a part of the transparent conductive coating layer is formed when the protective layer is formed. It is conceivable that a part of the coating composition is dissolved in the coating composition and the formed coating film is a mixture of the materials of both layers. From these viewpoints, the thickness of the protective layer needs to be in the range of 3 to 50 nm. When the thickness of the protective layer is less than the lower limit, sufficient solvent resistance cannot be obtained, and when the thickness exceeds the upper limit, the surface resistance is significantly reduced. A preferable thickness of the protective layer is in the range of 5 to 40 nm.

  The base film in the present invention is not particularly limited, but (meth) acrylic resin, polystyrene, polyvinyl acetate, polyolefin such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, polyimide, polyamide, polysulfone, Polyesters such as polycarbonate, polyethylene terephthalate (hereinafter sometimes referred to as PET), polyethylene naphthalate (hereinafter sometimes referred to as PEN), copolymers thereof, amino group epoxy groups, hydroxyl groups, carbonyls A film made of a resin partially modified with a functional group such as a group or a triacetyl cellulose (TAC) is preferable. Of these substrate films, polyester (PET, PEN and their copolymers) films are particularly preferred from the viewpoints of mechanical properties, transparency, and production costs. The thickness of the base film is not particularly limited, but is preferably 500 μm or less. When it is thicker than 500 μm, the rigidity is too strong and it is difficult to handle the obtained antireflection film when it is attached to a display.

  As a coating method for forming the protective layer and the transparent conductive coating layer, known methods can be used, for example, lip direct method, comma coater method, slit reverse method, die coater method, gravure roll coater method, blade Preferred examples include the coater method, spray coater method, air knife coat method, dip coat method, and bar coater method. When a thermosetting resin is used as a binder, the coating of the low refractive compound is performed by applying a coating liquid containing components for forming each of the low refractive compounds to a substrate and drying by heating to form a coating film. The heating conditions are preferably 80 to 160 ° C. for 10 to 120 seconds, particularly preferably 100 to 150 ° C. for 20 to 60 seconds. In the case where a UV curable resin or an EB curable resin is used as a binder, generally, after preliminary drying, ultraviolet irradiation or electron beam irradiation is performed.

  In addition, when applying to the base film, if necessary, physical surface treatment such as corona discharge treatment or plasma discharge treatment is applied to the film surface as a pretreatment for improving adhesion and coating properties. Alternatively, it is preferable to apply a chemical surface treatment for forming a coating film adhesion layer by applying an organic resin-based or inorganic resin-based paint during or after film formation.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, evaluation in an Example was performed as follows.
(1) Film thickness The film thickness of the protective layer is measured by a reflectance spectral film thickness meter (trade name “FE-3000” manufactured by Otsuka Electronics Co., Ltd.), and the wavelength of a typical refractive index is measured. The dispersion formula of nk Cauchy was cited as an approximate expression of dispersion, and the film thickness and refractive index were obtained by fitting with the measured values of the spectrum.
The thickness of the transparent conductive coating layer was measured at 10 arbitrary positions with a dot type thickness meter, and the average value thereof was taken as the thickness.
(2) Total light transmittance and haze Measured with a haze meter HCM-2B manufactured by Suga Test Instruments Co., Ltd. according to JIS K7150.
(3) Solvent resistance Gauze soaked with ethanol and ethyl acetate was rubbed 10 times on the protective layer side surface of the sample with a constant load of 150 g / cm ² , and the state of the coating film was visually evaluated. did. Judgment was made according to the following criteria: ○: No peeling of coating film ×: Peeling of coating film (4) Surface resistance Using Lorester MCP-T600 manufactured by Mitsubishi Chemical Corporation, in accordance with JIS K7194 Measured.
The measurement was performed five times at an arbitrary location, and the average value thereof was taken.

[Example 1]
<Formation of transparent conductive coating layer>
Conductive paint comprising poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid as main components and containing a silane coupling agent (manufactured by Nippon Agfa Gevaert Co., Ltd., trade name: Orgacon S-300) ) On a base film (PET film, manufactured by Teijin DuPont Films, trade name: O3PF8W-100) using a Mayer bar, and dried at 120 ° C. for 1 minute to obtain a transparent conductive coating layer. It was. The thickness of the transparent conductive coating layer was 1.0 μm.

<Formation of protective layer>
In a solution in which 22.5 g of tetraethoxysilane, 2.5 g of methyltriethoxysilane, 0.25 g of silicone oil, 18.8 g of ethanol, and 18.8 g of n-propanol were mixed and stirred, 17.5 g and 0 of ion-exchanged water were previously added. A solution prepared by mixing 6.0 g of 0.001N hydrochloric acid was added, the whole amount was added, stirred for 10 minutes, and then allowed to stand for 20 hours to proceed the hydrolysis reaction. A solution obtained by diluting this solution with ethanol three times was coated on the above-mentioned transparent conductive coating layer using a Mayer bar to form a protective layer to obtain a transparent conductive film. The thickness of the protective layer was 10 nm.
Table 1 shows the properties of the obtained conductive film.

[Example 2]
The same operation as in Example 1 was repeated except that the film thickness of the transparent conductive coating layer was 1.5 μm. Table 1 shows the properties of the obtained conductive film.

[Example 3]
The same operation as in Example 1 was repeated except that the film thickness of the transparent conductive coating layer was 2 μm. Table 1 shows the properties of the obtained conductive film.

[Example 4]
The same operation as in Example 1 was repeated except that the thickness of the protective layer was 25 nm. Table 1 shows the properties of the obtained conductive film.

[Example 5]
The same operation as in Example 1 was repeated except that the thickness of the protective layer was changed to 5 nm. Table 1 shows the properties of the obtained conductive film.

[Comparative Example 1]
The same operation as in Example 1 was repeated except that the protective layer was not formed. Table 1 shows the properties of the obtained conductive film.

[Comparative Example 2]
The same operation as in Example 1 was repeated except that the thickness of the protective layer was changed to 70 nm. Table 1 shows the properties of the obtained conductive film.

[Comparative Example 3]
The same operation as in Example 1 was repeated except that the thickness of the protective layer was 2 nm. Table 1 shows the properties of the obtained conductive film.

  As can be seen from Table 1, by forming a protective layer with a specific thickness on the transparent conductive coating layer, the solvent resistance can be greatly improved without greatly affecting the surface resistance value.

An example of sectional drawing of the antireflection film of the present invention is shown.

Explanation of symbols

1 base film 2 transparent conductive coating layer 3 protective layer

Claims (7)

A protective film having a thickness of 3 to 50 nm comprising a base film, a transparent conductive coating layer and a reaction product of a metal alkoxide is laminated in this order,
A conductive film having a total light transmittance of 60% or more and a surface resistance on the protective layer side of the conductive film in the range of 10 to 1 × 10 ⁵ Ω / □. The transparent conductive coating layer has the following general formula

(Wherein, R ¹ and R ² each independently represent hydrogen or a C 1-4 alkyl group, or a C 1-12 alkylene group which may be optionally substituted together) The conductive film according to claim 1, comprising a conductive polymer of a polycationic polythiophene comprising a repeating unit represented by formula (II) and a polyanion.   The transparent conductive coating layer comprises at least one reaction product selected from the group consisting of the conductive polymer and a tetraalkoxysilane and a trialkoxysilane having a reactive functional group other than an alkoxy group. 2. The conductive film according to 2.   The conductive film according to claim 3, wherein the transparent conductive coating layer comprises the conductive polymer and a reaction product of trialkoxysilane having a glycidoxy group.   The conductive film according to claim 1, wherein the protective layer comprises a reaction product of alkoxysilane. The conductive film according to claim 1, wherein the transparent conductive coating layer has a surface resistance in the range of 10 to 1 × 10 ⁵ Ω / □.   A method for producing a conductive film, comprising: forming a transparent conductive coating layer on one side of a substrate film; and further forming a protective layer having a thickness of 3 to 50 nm comprising a reaction product of a metal alkoxide on the transparent conductive coating layer .

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