KR20190107751A - Optical film and method for manufacturing optical film - Google Patents

Abstract

An object of the present invention is to provide an optical film capable of suppressing light escape from the end face EF in the flexible device, and a device using the same.
The optical film of this invention is a transparent optical film containing a polyimide type polymer, and the edge part EP of an optical film is colored. The end EP may have a color of 2YR to 3Y in a Munsell color system, or may be achromatic. It is preferable that coloring of the said end has a color of 2YR-3Y or is achromatic on a white background in a Munsell color system.

Description

Optical film and manufacturing method of optical film {OPTICAL FILM AND METHOD FOR MANUFACTURING OPTICAL FILM}

The present invention relates to an optical film and a method for producing the optical film.

In devices having displays such as smartphones and tablet PCs, narrow bezels of displays are being demanded, and the design of optical paths around the film edges has become important. By using a white member at the end, it is possible to use reflected light or to absorb unnecessary light by using a black member. Luminance increase and luminance nonuniformity reduction by design are proposed (refer patent document 1).

In a flexible device, the transparent resin film is examined as a front plate. For example, use of the film containing a polyimide polymer as a front plate is examined (refer patent document 2).

Japanese Unexamined Patent Application Publication No. 09-5740 Japanese Unexamined Patent Application Publication No. 2016-93992

Also in a flexible device, it is necessary to design so that the luminance nonuniformity of a display edge part, the efficiency deterioration by which light escapes from the edge part vicinity, the case where unnecessary light leaks out and a design property will fall may not arise.

This invention is made | formed in view of the said subject, and an object of this invention is to provide the optical film which can suppress the light escape from the cross section in a flexible device, and a flexible device using the same.

The optical film which concerns on this invention is a transparent optical film containing a polyimide polymer, The edge part of the said optical film is colored.

According to the present invention, the light escape from the light from the inside to the outside through the cross section is suppressed by the coloring of the end portion. Therefore, the light which escapes from the end to the outside can be suppressed regardless of the member of the frame.

Here, coloring of the said end part may have a color of 2YR-3Y on a white background in a Munsell color system, or may be achromatic.

Moreover, the coloring of the said edge part may have a color of 3YR-10YR on a white background in a Munsell color system.

In addition, the thickness may be 20 to 100 µm.

This invention also relates to the manufacturing method of an optical film which colored an edge part by laser irradiation. In this manufacturing method, the optical film may be a transparent optical film containing a polyimide polymer.

The front plate for flexible devices which concerns on this invention has any one of said optical films.

The flexible device which concerns on this invention has a flexible functional layer and any of said optical films.

According to this invention, the optical film which can suppress the light escape from the cross section in a flexible device, and the flexible device using the same are provided.

1 is a perspective view illustrating an example of an optical film according to an embodiment of the present invention.
2 is a perspective view showing an example of a flexible display according to an embodiment of the present invention.

The optical film 10 which concerns on this embodiment is a transparent optical film containing a polyimide type polymer, As shown in FIG. 1, the edge part EP of this optical film 10 is colored.

The end EP is a portion along the end face EF of the optical film 10. As seen from the direction perpendicular to the surface of the optical film 10, the width W of the edge part EP can be 10-500 micrometers. The whole of the annular end EP along all the end surfaces EF may be colored, but only a part of the annular end EP (for example, the part along one end surface EF) may be colored. .

Coloring is expressed in the Munsell color system. Coloring means that even if the film is placed on the background color of white (N9 in the Munsell color system), even if the film is placed on the background color of light green (10GY8 / 6 in the Munchen color system), the end EP is substantially in the Munsell color system. What is determined to be the same color. The fact that it is determined to be substantially the same color means that the difference in color is within 5 (for example, the background color is 2YR-10YR or 1Y-2Y in light green for the end portion where the color is 7YR when the background color is white). In addition, it means that the difference in saturation and lightness is both 2 or less.

More preferably, it is most preferable if the difference in color is within 3, the difference in saturation and lightness is each within 1, and all are determined to be the same value.

On the other hand, since the edge part EP of the conventional transparent polyimide-type film which is not colored has a transmittance | permeability more than a fixed level, it determines with different colors depending on background color. Specifically, in the Munsell evaluation value in the case of a white background and the Munsell evaluation value in the case of a light green background, (a) the color is 6 or more, (b) the saturation is 3 or more, and (c) the brightness is 3 or more. When at least one is satisfied, no coloration occurs.

Coloration may be a chromatic color (saturation exceeds 0), and achromatic color N (saturation 0) may be sufficient as it.

Preferred colors are 2YR to 3Y or achromatic (N) on a white background in the Munsell color system. More preferable colors are 3YR-10YR. Such coloring of the end is preferable because it is easily obtained by laser cutting.

From the viewpoint of not making the color of the end EP stand out, the color, the saturation and the brightness can be appropriately adjusted within these ranges, so that the color similar to the member arranged around the optical film 10 can be obtained.

The evaluation in the Munsell color system of the color of the end EP can be performed by comparing the color sample of the Munsell color system with the color of the end EP. Observation of the color of the end EP of the optical film 10 is performed by observing the end EP from the direction perpendicular to the surface of the optical film 10. When observing the end EP, observe with a microscope. The film is placed on the background color of the bag (N9 in the Munsell color system) and compared to the color swatch to determine the hue, saturation and lightness in the Munsell color system, and then to the background color of pale green (10GY8 / 6 in the Munsell color system). The color, saturation, and lightness in the Munsell color system are determined, and the color at which the end EP is substantially the same in any background color, i.e., the difference in color is within 5 and the difference in saturation and light is determined within 2 It is judged that the film is colored when having.

The said optical film 10 has a refractive index of 1.45-1.7 normally, Preferably it is 1.5-1.66.

Although the thickness of the optical film 10 is suitably adjusted according to the kind etc. of a flexible device, it is 10-500 micrometers normally, It is preferable that it is 15-200 micrometers, It is more preferable that it is 20-100 micrometers.

As for the optical film 10, the total light transmittance based on JISK7105: 1981 is 85% or more normally, Preferably it is 90% or more.

Haze based on JISK7105: 1981 may be 1 or less, and the optical film 10 may be 0.9 or less.

In addition, refractive index, total light transmittance, and Haze are the values measured in the thickness direction of an optical film.

The size of the optical film 10 can be suitably adjusted according to the size of the flexible device used. Moreover, the shape of the optical film 10 is not limited to a rectangle, but can be adjusted suitably according to flexible devices, such as an ellipse, a trapezoid, and a circle.

(Material of the film)

(Transparent resin)

The optical film contains a transparent resin such as a polyimide polymer.

(Polyimide Polymer)

In this specification, a polyimide is a polymer containing the repeating structural unit containing an imide group, and a polyamide is a polymer containing the repeating structural unit containing an amide group. The polyimide polymer refers to a polymer containing a repeating structural unit containing both a polyimide and an imide group and an amide group.

The polyimide polymer which concerns on this embodiment can manufacture the tetracarboxylic acid compound and diamine compound mentioned later as a main raw material, and has a repeating structural unit represented by Formula (10). Here, G is a tetravalent organic group and A is a divalent organic group. G and / or A may include the structure represented by two or more types of formulas (10).

Moreover, the polyimide polymer which concerns on this embodiment may contain the structure represented by either of formula (11)-formula (13) in the range which does not impair the various physical properties of the obtained polyimide polymer film.

The polyimide polymer is preferable from the viewpoint of the strength and transparency of the film as long as the repeating structural unit represented by the formula (10) is a main structural unit of the polyimide polymer. The repeating structural unit represented by the formula (10) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% with respect to all the repeating structural units of the polyimide polymer. It is above, Especially preferably, it is 90 mol% or more, More preferably, it is 98 mol% or more. 100 mol% may be sufficient as the repeating structural unit represented by Formula (10).

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

G and G ¹ is a tetravalent organic group, preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, formula 20, formula 21, formula 22, formula (23) The group represented by Formula (24), Formula (25), Formula (26), Formula (27), Formula (28) or Formula (29) and a tetravalent C6 or less chain hydrocarbon group are illustrated. In the formula, * represents a bond, Z represents a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -Ar-, -SO _2- , -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C ( CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents the C6-C20 arylene group which may be substituted by the fluorine atom, and a phenylene group is mentioned as a specific example. G and G ¹ are, because it is easy to suppress the yellowness of the resultant film, it is preferable that expression (20) - any group selected from groups represented by the formula (27).

[Formula 5]

G ² is a trivalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and is formula (20), formula (21), formula (22), formula (23), formula A group in which any one of the bonds of the group represented by (24), (25), (26), (27), (28) or (29) is substituted with a hydrogen atom and a trivalent carbon number of 6 or less The chain hydrocarbon group of is illustrated.

G ³ is a divalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and is formula (20), formula (21), formula (22), formula (23), and formula Of the bonds of the group represented by (24), (25), (26), (27), (28) or (29), two non-adjacent groups substituted with hydrogen atoms and carbon number 6 The following chain hydrocarbon groups are illustrated.

A, A ¹ , A ² , and A ³ are all divalent organic groups, preferably organic groups which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and are formulas (30), (31), and formula ( A group represented by 32), (33), (34), (35), (36), (37) or (38); Groups in which they are substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group and a chain hydrocarbon group having 6 or less carbon atoms are exemplified.

In the formula, * represents a bond, and Z ¹ , Z ² and Z ³ each independently represent a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or -CO-. One example is that Z ¹ and Z ³ are -O-, and Z ² is -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -or -SO _2- . It is preferable that Z <^1> , Z <^2> , Z <^2> and Z <^3> are a meta position or a para position with respect to each ring, respectively.

[Formula 6]

The polyamide which concerns on this embodiment is a polymer which mainly uses the repeating structural unit represented by Formula (13). Preferred examples and specific examples are the same as those of G ³ and A ³ in the polyimide polymer. G ³ and / or A ³ may include a structure represented by two or more kinds of formulas (13).

The polyimide polymer is obtained by, for example, polycondensation of a diamine and a tetracarboxylic acid compound (tetracarboxylic dianhydride, etc.), for example, JP-A-2006-199945 or JP-A It can synthesize | combine according to the method described in Unexamined-Japanese-Patent No. 2008-163107. As a commercial item of a polyimide, Mitsubishi Gas Chemical Co., Ltd. neoprelime etc. are mentioned.

As tetracarboxylic acid compound used for the synthesis | combination of a polyimide, aliphatic tetracarboxylic acid compounds, such as aromatic tetracarboxylic dianhydride, and aliphatic tetracarboxylic acid compounds, such as aliphatic tetracarboxylic dianhydride, are mentioned. The tetracarboxylic acid compound may be used independently or may use 2 or more types together. A tetracarboxylic-acid compound flexible body, such as an acid chloride compound, may be sufficient as a tetracarboxylic-acid compound.

Specific examples of the aromatic tetracarboxylic dianhydride include 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzo Phenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4, 4'-diphenylsulfontetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2, 2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl) Ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4- Dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 '-(p-phenylene Oxy) diphthalic dianhydride, 4,4 '-(m-phenylenedioxy) diphthalic dianhydride, and 2,3,6,7-naphthalenetetracarboxylic dianhydride, and preferably 4,4' Oxydiphthalic acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic acid dianhydride, 3,3 ', 4, 4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfontetracarboxylic dianhydride, 2, 2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) Propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3- Dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4 -Dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 '-(p-phenylenedioxy) diphthalic acid dianhydride and 4,4'-(m-phenylenedi Oxy) diphthalic acid dianhydride is mentioned. These can be used individually or in combination of 2 or more types.

As aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride is mentioned. Cyclic aliphatic tetracarboxylic dianhydride is tetracarboxylic dianhydride which has alicyclic hydrocarbon structure, As a specific example, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclo Cycloalkanetetracarboxylic dianhydride, such as butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5 And 6-tetracarboxylic dianhydride, dicyclohexyl 3,3 ', 4,4'-tetracarboxylic dianhydride and regioisomers thereof. These can be used individually or in combination of 2 or more types. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like, and these alone or It can be used in combination of 2 or more type.

Among the tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3, from the viewpoint of high transparency and low colorability Preference is given to 5,6-tetracarboxylic acid dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride.

Moreover, the polyimide polymer which concerns on this embodiment adds tetracarboxylic acid, in addition to the anhydride of tetracarboxylic acid used for the said polyimide synthesis, in the range which does not impair the various physical properties of the obtained polyimide polymer film. Tricarboxylic acid and dicarboxylic acid, and their anhydrides and derivatives may be further reacted.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and flexible acid chloride compounds and acid anhydrides, and two or more kinds may be used in combination. Specific examples include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3- anhydride; And phthalic anhydride and benzoic acid are linked by a single bond, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or a phenylene group.

As a dicarboxylic acid compound, aromatic dicarboxylic acid, aliphatic dicarboxylic acid, those flexible acid chloride compounds, an acid anhydride, etc. are mentioned, You may use 2 or more types together. Specific examples include terephthalic acid; Isophthalic acid; Naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; Dicarboxylic acid compounds of a chain hydrocarbon having 8 or less carbon atoms, and two benzoic acids are bonded to a single bond, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or phenylene group. The compound connected by is mentioned.

As a diamine used for the synthesis | combination of a polyimide, aliphatic diamine, aromatic diamine, or a mixture thereof may be sufficient. In addition, in this embodiment, "aromatic diamine" represents the diamine which the amino group couple | bonded with the aromatic ring directly, and may contain the aliphatic group or other substituent in a part of the structure. The aromatic ring may be monocyclic or a condensed ring, and a benzene ring, naphthalene ring, anthracene ring, fluorene ring and the like are exemplified, but are not limited thereto. Among these, Preferably they are a benzene ring. Moreover, "aliphatic diamine" shows the diamine which the amino group couple | bonded with the aliphatic group directly, and may contain the aromatic ring and other substituent in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4 '. Cyclic aliphatic diamine, such as diamino dicyclohexyl methane, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2, Aromatic diamines having one aromatic ring, such as 6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylether, 3,3'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-dia Minodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, bis [4- (4-amino phenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane , 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) Influenza Orene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (4-amino-3-chlorophenyl) fluorene, 9,9-bis (4-amino-3-fluor Aromatic diamine which has two or more aromatic rings, such as rophenyl) fluorene, is mentioned, These can be used individually or in combination of 2 or more types.

Among the diamines, from the viewpoint of high transparency and low colorability, it is preferable to use one or more selected from the group consisting of aromatic diamines having a biphenyl structure. Consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenylether It is more preferable to use one or more selected from the group, and more preferably 2,2'-bis (trifluoromethyl) benzidine is included.

The polyimide polymer and the polyamide, which are polymers containing at least one repeating structural unit represented by any one of formulas (10) to (13), include a diamine and a tetracarboxylic acid compound (acid chloride compound, tetracarboxylic acid 2). Tetracarboxylic acid compound flexible body such as anhydride), Tricarboxylic acid compound (Tricarboxylic acid compound flexible body such as acid chloride compound and tricarboxylic acid anhydride), and Dicarboxylic acid compound (Dicarboxylic acid compound flexible body such as acid chloride compound) It is a condensation type polymer which is a polycondensation product with at least 1 type of compound contained in the group which consists of In addition to these, a dicarboxylic acid compound (including flexible bodies, such as an acid chloride compound) may be used as a starting raw material. The repeating structural unit represented by Formula (11) is usually derived from diamines and tetracarboxylic acid compounds. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by formula (13) is usually derived from a diamine and a dicarboxylic acid compound. Specific examples of the diamine and tetracarboxylic acid compounds are as described above.

The standard polystyrene reduced weight average molecular weight of the polyimide polymer and the polyamide according to the present embodiment is usually 10,000 to 500,000, preferably 50,000 to 500,000, and more preferably 100,000 to 400,000. The larger the weight average molecular weight of the polyimide polymer and the polyamide, the more likely it is to express high flex resistance when filmed. However, if the weight average molecular weight of the polyimide polymer and the polyamide is too large, the viscosity of the varnish becomes high and the processability is increased. This tends to be lowered.

By including a fluorine-containing substituent, the polyimide polymer and the polyamide tend to reduce the YI value while improving the elastic modulus when forming a film. If the elastic modulus of the film is high, the occurrence of scratches and wrinkles tends to be suppressed. In view of transparency of the film, the polyimide polymer and the polyamide preferably have a fluorine-containing substituent. As a specific example of a fluorine-containing substituent, a fluoro group and a trifluoromethyl group are mentioned.

The content of the fluorine atom in the polyimide polymer and the polyamide is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass, based on the mass of the polyimide polymer or the polyamide. It is more than 40 mass%.

In the optical film according to the present embodiment, the content of the polyimide polymer is 40% by mass or more, preferably 50% by mass or more, and more preferably 60% by mass or more.

(Inorganic particles)

The optical film which concerns on this embodiment may further contain inorganic materials, such as an inorganic particle, in addition to said polyimide polymer and / or polyamide.

As an inorganic material, Preferably silicon particle, such as a quaternary alkoxysilane, such as a silica particle and ortho silicate tetraethyl (TEOS), A silica particle is preferable from a varnish stability viewpoint.

The average primary particle diameter of the silica particles is preferably 10 to 100 nm, more preferably 20 to 80 nm. If the average primary particle diameter of a silica particle is 100 nm or less, there exists a tendency for transparency to improve. When the average primary particle diameter of the silica particles is 10 nm or more, the cohesive force of the silica particles is weakened, so that it tends to be easy to handle.

Although the silica fine particle which disperse | distributed silica particle to the organic solvent etc. may be used, the silica fine particle which concerns on this embodiment may use the silica fine particle powder manufactured by the vapor phase method, but since it is easy to handle, it is preferable that it is a silica sol.

The (average) primary particle diameter of the silica particle in an optical film can be calculated | required by observation with a transmission electron microscope (TEM). The particle size distribution of silica particles before forming an optical film can be calculated | required with a commercially available laser diffraction type particle size distribution system.

In the optical film according to the present embodiment, the inorganic material is 0% by mass or more and 90% by mass or less. Preferably they are 10 mass% or more and 60 mass% or less, More preferably, they are 20 mass% or more and 50 mass% or less. If the compounding ratio of the polyimide polymer, the polyamide, and the inorganic material (silicon material) is within the above range, there is a tendency to make the transparency and mechanical strength of the optical film compatible.

(UV absorber)

The optical film may contain 1 type, or 2 or more types of ultraviolet absorbers. A ultraviolet absorber can be suitably selected from what is normally used as a ultraviolet absorber in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400 nm or less. As a ultraviolet absorber, the at least 1 sort (s) of compound chosen from the group which consists of a benzophenone type compound, a salicylate type compound, a benzotriazole type compound, and a triazine type compound is mentioned, for example.

In addition, in this specification, a "system compound" refers to the derivative of the compound to which the said "system compound" is affixed. For example, a "benzophenone type compound" refers to the compound which has a benzophenone as a mother skeleton and a substituent couple | bonded with benzophenone.

(Other additives)

The optical film may further contain other additives in a range that does not impair transparency and flexibility. As other components, coloring agents, such as antioxidant, a mold release agent, a stabilizer, a bluing agent, a flame retardant, a lubricating agent, a thickener, a leveling agent, etc. are mentioned, for example.

It is preferable that components other than a resin component and an inorganic material are 0% or more and 20 mass% or less with respect to the mass of an optical film. More preferably, it is more than 0% and 10 mass% or less.

(Production method)

Next, an example of the manufacturing method of the optical film of this embodiment is demonstrated.

The varnish used for preparation of the optical film which concerns on this embodiment is the reaction of the polyimide type polymer and / or polyamide obtained, for example by selecting and reacting from the said tetracarboxylic-acid compound, the said diamine, and the said other raw materials. It can prepare by mixing and stirring a liquid, the said solvent, and the said ultraviolet absorber and the other additive used as needed. Instead of a reaction solution such as a polyimide polymer, a solution such as a purchased polyimide polymer or a solution such as a purchased polyimide polymer may be used.

Next, polyimide is formed by applying the above liquid onto a resin substrate, a stainless steel belt, or a glass substrate by a known roll-to-roll or batch method to form a coating film, drying the coating film, and peeling from the substrate. A film containing a system polymer is obtained. You may further dry a film after peeling.

Drying of a coating film is performed by evaporating a solvent at the temperature of 50-350 degreeC. Drying may be performed under air, under an inert atmosphere, or under reduced pressure.

PET, PEN, polyimide, polyamideimide, etc. are mentioned as an example of a resin base material.

Resin excellent in heat resistance is preferable. In particular, a PET substrate is preferred from the viewpoint of adhesion to the film and cost.

Then, the edge part EP of a film is colored. Coloring can be performed by dyeing the edge part EP with dye, for example.

For example, application of a dye solution to the end EP enables dyeing of the end. There is no restriction | limiting in particular in dye. The aspect of coloring can be controlled easily by mix | blending of dye in a dye solution, adjustment of a density | concentration, etc.

Moreover, coloring of the edge part EP can also be performed by irradiating a laser. Suitable lasers are CO ₂ lasers. Specifically, by cutting the film disc with a CO ₂ laser to a desired size, colored ends EP are formed along the cross section EF. Although the principle of coloring of the edge part EP by laser irradiation is unclear, it is thought that the denaturation of the component in a film, for example, a polyimide type compound contributes.

When using a laser, since a laser irradiation part can also be cut | disconnected, coloring of an edge part can be performed simultaneously with the cutting process of a film, and a process can be simplified.

As a method of controlling the coloring by a laser, the method of changing the structure of a polyimide, the method of controlling the output of a laser, etc. are mentioned. For example, if it is a polyimide which contains an aliphatic structure in a part of main chain, there exists a tendency for the brightness of coloring to increase easily. In the case of a wholly aromatic polyimide, there exists a tendency for the brightness of the coloring of an edge part to fall easily. When the laser output is lowered, the brightness of coloring tends to be higher. Therefore, when the laser output is higher, the brightness of coloring can be made lower.

In addition, an all aromatic polyimide means the polyimide which has an aromatic group in both G and A in each structural formula of said (10)-(13) formula.

(Usage)

Such an optical film can be used suitably as a front plate of a flexible device. The flexible device which concerns on this embodiment has the flexible functional layer and said optical film which overlaps with a flexible functional layer, and functions as a front plate. That is, the front plate of the flexible device is arranged on the viewing side on the flexible functional layer. This front plate has a function of protecting the flexible functional layer.

As an example of a flexible device, an image display apparatus (flexible display, electronic paper, etc.), a solar cell, etc. are mentioned. For example, a display functional layer and a solar cell functional layer become a flexible functional layer.

An example of a flexible display is shown in FIG. This flexible display 100 is a front plate 110 / polarizing plate protective film 120B / polarizer 120A / polarizing plate protective film 120B / touch sensor film 130 / organic in order from the surface side (viewing side) It has the structure called EL element layer 140 / TFT substrate 150. Layers other than the front plate 110 in the flexible display 100 are the flexible functional layer 190. The polarizing plate protective film 120B / polarizer 120A / polarizing plate protective film 120B comprises the polarizing plate 120. A hard coating layer, an adhesion layer, an adhesion layer, a retardation layer, etc. may be included between the surface of each layer and between each layer. The optical film 10 described above can be used as the front plate 110. Such a flexible display can be used as an image display unit of a tablet PC, a smartphone, a portable game machine, and the like.

According to the flexible device which concerns on this embodiment, the said optical film 10 is used as the front plate 110. FIG. The edge part EP of the optical film 10 is colored, and can prevent the light exiting to the exterior from the end surface EF.

By coloring of the edge part EP, it becomes possible to suppress the phenomenon which the light which passes through a film center in thickness direction scatters and escapes from an end surface. It is thought that the light toward the end surface EF is attenuated by reflection, absorption, etc. of the light in a coloring part, and, as a result, light exit from an edge part is suppressed.

Moreover, it can also be set as the laminated body which added various functional layers, such as an ultraviolet absorbing layer, a hard coating layer, an adhesion layer, a color adjustment layer, and a refractive index adjustment layer, to the surface of this optical film.

EXAMPLE

Although an Example and a comparative example demonstrate this invention further more concretely below, this invention is not limited to a following example.

(Example 1)

A commercially available polyimide polymer solution ("Neoprim C6A20" manufactured by Mitsubishi Gas Chemical Co., Ltd.) (varnish 1) is cast on a substrate to form a film, and a polyimide polymer film disc (polyimide A) having a thickness of 50 μm may be called. Yes). The refractive index of the film disc was 1.56. Thereafter, the film disk cut out an area of a rectangle (100 ㎜ × 100 ㎜) a CO ₂ laser to obtain an optical film.

CO ₂ laser irradiation was under the following conditions.

Device: ML-Z9510T made by Keyence

Wavelength: 9.3 μm

Output: 80%

Machining speed: 150 mm / sec

The end EP of the film was colored. The hue in the Munsell color system of the end (EP) of the film on the white background and the light green background was 5 YR, the brightness was 9, and the saturation was 2.

(The preparation of varnish 2)

Polyimide polymer solution "Neoprim C6A20" made by Mitsubishi Gas Chemical Co., Ltd. ((gamma) -butyrolactone solvent, 22 mass%), the solution which disperse | distributed the silica particle of solid content concentration 30 mass% in (gamma) -butyrolactone, and an amino group The dimethylacetamide solution of the alkoxysilane having and water was mixed and stirred for 30 minutes to obtain a polymer solution (varnish 2). Here, the mass ratio of silica and a polyimide polymer is 30:70, and the quantity of the alkoxysilane which has an amino group is 1.67 parts with respect to a total of 100 mass parts of a silica and a polyimide polymer, and water is 100 mass parts in total of a silica and a polyimide. It was 10 mass parts with respect to.

(Example 2)

It carried out similarly to Example 1 except having obtained the raw film film (sometimes called polyimide B) from varnish 2. The end EP of the film was colored. The hue in the Munsell color system of the end (EP) of the film on the white background and the light green background was 5 YR, the brightness was 9, and the saturation was 2. The refractive index of the film disc was 1.57.

(The preparation of varnish 3)

A polyimide polymer (KPI-MX300F manufactured by Kawamura Industries Co., Ltd.) was dissolved in γ-butyrolactone to obtain a polymer solution (varnish 3) having a polymer concentration of 18% by mass.

(Example 3)

Using a varnish 3, that the thickness of the film disk (called polyimide C) to 80 ㎛, except that CO ₂ was subjected to laser irradiation under the following conditions were the same as in Example 1. The refractive index of the film disc was 1.56.

Device: E400iCL made by COHERENT

Optical system: Digital scanner fθ lens 70 mm x 70 mm

Wavelength: 9.4 μm

Output: 17 W

Machining speed: 400 mm / sec

Frequency: 60 Hz

The end EP of the film was colored. The hue in the Munsell color system of the end (EP) of the film on the white background and the light green background was 7.5 YR, the brightness was 2, and the saturation was 4.

(Comparative Example 1)

It carried out similarly to Example 2 except having cut out the rectangular area | region from the film disk with a blade (share blade). The end EP of the film was not colored. Munsell evaluation values on a white background and a light green background are shown in Table 1.

(Comparative Example 2)

It carried out similarly to Example 3 except having cut out the rectangular area | region from the film disk with a blade (share blade). The end EP of the film was not colored. Munsell evaluation values on a white background and a light green background are shown in Table 1.

(evaluation)

Light escape from the end surface EF was evaluated as follows. A 10 cm wide film was sandwiched between two frames of stainless steel 10 cm wide, 1 cm wide, and 1.5 mm thick, and the frame was fixed with a clip. Using LA-HDF15T (LED light source) manufactured by Hayashi Clock Co., Ltd., which removed the lens, the output of the device was maximized, and light irradiation was performed on the center portion of the frame of the frame in the dark room. The frame was observed from the side to observe the light escape from the end face EF of the film sandwiched in the frame. The thing that light exit was observed x and that light exit were suppressed were evaluated as (circle). The results are shown in Table 1. In the Example with coloring in the edge part EP, the light escape from the end surface EF was suppressed compared with the comparative example.

10: optical film, 100: flexible display.

Claims (10)

The transparent optical film containing a polyimide-type polymer, The edge part of the said optical film is colored, The optical film whose refractive index is 1.45-1.7. The method of claim 1,
The coloring of the said edge part has a color of 2YR-3Y on a white background in a Munsell color system, or is an achromatic color. The method of claim 1,
The coloring of the said edge part has the color of 3YR-10YR on a white background in a Munsell color system. The method according to any one of claims 1 to 3,
The optical film whose thickness is 20-100 micrometers. The manufacturing method of the optical film whose refractive index is 1.45-1.7 which colorizes an edge part by laser irradiation. The method of claim 5,
The manufacturing method of the optical film whose optical film is a transparent optical film containing a polyimide type polymer. The front plate for flexible devices provided with the optical film as described in any one of Claims 1-3. The front plate for flexible devices provided with the optical film of Claim 4. The flexible device which has a flexible functional layer and the optical film of any one of Claims 1-3. The flexible device which has a flexible functional layer and the optical film of Claim 4.

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