TW202122471A - Optical film and flexible display device containing a polyamide-based resin and having excellent bending resistance and a high elastic modulus - Google Patents

Abstract

The present invention provides an optical film containing a polyamide-based resin and having excellent bending resistance and a high elastic modulus. An optical film contains a polyamide-based resin. When the thickness of the optical film is set as A [mu]m, an arbitrary position on one surface of the optical film is taken as D0, a position which is A*1/4 [mu]m away from D0 in the thickness direction is taken as D1, a position which is A*1/2 [mu]m away from D0 in the thickness direction is taken as D2, a position which is A*3/4 [mu]m away from D0 in the thickness direction is taken as D3, and the intensity of the largest peak in the range of 1,550~1,650 cm -1 measured by Raman spectroscopy at each position of D1 to D3 is set as I1 to I3 respectively, the optical film satisfies at least one of formula (1) and formula (2): I1/I2 ≤ 0.97 (1), I3/I2 ≤ 0.97 (2).

Description

Optical film and flexible display device

The present invention relates to an optical film containing polyamide resin and a flexible display device provided with the optical film.

Image display devices such as liquid crystal display devices and organic EL (Electroluminescence) display devices are widely used in various applications such as mobile phones and smart watches. Glass has been used as the front panel of this type of image display device. However, the glass is very rigid and easy to break, so it is difficult to use it as a front panel material such as a flexible display. As an optical film instead of glass, for example, a plastic film containing a polyimide resin has been studied (for example, Patent Document 1). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-119132

[The problem to be solved by the invention]

Various optical films using polyamide resins are known, but there is still a need to further improve the bending resistance. In addition, from the viewpoint of preventing damage to the optical film, it is still necessary to increase the modulus of elasticity. Therefore, the subject of the present invention is to provide an optical film containing a polyamide resin and having excellent bending resistance. [Technical means to solve the problem]

。 [2]如上述[1]所記載之光學膜，其中滿足上述式(1)之I₁ /I₂ 或滿足上述式(2)之I₃ /I₂ 為0.3以上。 [3]如上述[1]或[2]所記載之光學膜，其中光學膜之彈性模數為5.5 GPa以上。 [4]如上述[1]至[3]中任一項所記載之光學膜，其中光學膜之全光線透過率為80%以上。 [5]如上述[1]至[4]中任一項所記載之光學膜，其中聚醯胺系樹脂之重量平均分子量為250,000以上。 [6]如上述[1]至[5]中任一項所記載之光學膜，其中聚醯胺系樹脂係聚醯胺醯亞胺樹脂。 [7]如上述[1]至[6]中任一項所記載之光學膜，其係可撓性顯示裝置之前面板用膜。 [8]一種可撓性顯示裝置，其具備如上述[1]至[7]中任一項所記載之光學膜。 [9]如上述[8]所記載之可撓性顯示裝置，其進而具備觸控感測器。 [10]如上述[8]或[9]所記載之可撓性顯示裝置，其進而具備偏光板。 [發明之效果]In order to solve the above-mentioned problems, the inventor of the present invention made painstaking research and found that the manufacturing conditions of the optical film may affect the bending resistance and elastic modulus of the optical film, and further research was conducted. As a result, it was found that when the peak intensity measured by Raman spectroscopy in the optical film satisfies a specific formula, the bending resistance and elastic modulus of the optical film can be further improved, thereby completing the present invention. That is, the present invention includes the following aspects. [1] An optical film containing polyamide resin, the thickness of the optical film is set to A μm, an arbitrary position on one surface of the optical film is set to D ₀ , and the thickness direction is equal to D _{Set the position between 0} and D ₀ by A×1/4 μm as D ₁ , and set the position from D 0 by A×1/2 μm in the _{thickness direction as D 2} , and set the _{distance from D 0 in the} thickness direction by A×3/4 μm the D position is set to _3, the respective positions D ₁ ~ D ₃ obtained by the measurement of the Raman spectroscopy 1,550 ~ intensity within the range of the maximum peak of 1,650 cm ^-1, respectively, of I ₁ ~ I to _3, the The optical film satisfies at least one of formula (1) and formula (2): [Number 1]

. [2] The optical film as described in [1] above, wherein I ₁ /I ₂ satisfying the above formula (1) or I ₃ /I ₂ satisfying the above formula (2) is 0.3 or more. [3] The optical film as described in [1] or [2] above, wherein the elastic modulus of the optical film is 5.5 GPa or more. [4] The optical film as described in any one of [1] to [3] above, wherein the total light transmittance of the optical film is 80% or more. [5] The optical film as described in any one of [1] to [4] above, wherein the weight average molecular weight of the polyamide-based resin is 250,000 or more. [6] The optical film according to any one of [1] to [5] above, wherein the polyamide resin is a polyamide resin. [7] The optical film as described in any one of [1] to [6] above, which is a film for a front panel of a flexible display device. [8] A flexible display device including the optical film described in any one of [1] to [7] above. [9] The flexible display device described in [8] above, which further includes a touch sensor. [10] The flexible display device as described in [8] or [9] above, which further includes a polarizing plate. [Effects of Invention]

According to the present invention, it is possible to provide an optical film having excellent bending resistance and a high elastic modulus.

Hereinafter, embodiments of the present invention will be described in detail. Furthermore, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without departing from the spirit of the present invention.

換言之，可使I₁ /I₂ 及I₃ /I₂ 中任一者為0.97以下，另一者超過0.97，亦可使I₁ /I₂ 及I₃ /I₂ 兩者為0.97以下。<Optical film> If the optical film of the present invention contains a polyamide resin, the thickness of the optical film is A μm, and any position on one surface of the optical film is D ₀ , and the thickness direction is equal to The position of D ₀ away from D 0 by A×1/4 μm is set to D ₁ , _{the position away from D 0} by A×1/2 μm in the thickness direction is _{set to D 2 , and the distance from D 0 in the} thickness direction is A×3/4 When the position of μm is set to D ₃ , and the intensity of the largest peak in the range ^{of 1,550 to 1,650 cm -1} measured by Raman spectroscopy at each position of _{D 1} to D _{3 is set to I 1} to I ₃ respectively, The optical film satisfies at least one of formula (1) and formula (2). [Number 2]

In other words, one of I ₁ /I ₂ and I ₃ /I ₂ may be 0.97 or less, and the other may exceed 0.97, and both I ₁ /I ₂ and I ₃ /I ₂ may be 0.97 or less.

It is considered that ^{the largest peak in the range of 1,550-1,650 cm -1} measured by Raman spectroscopy is attributed to the peak of the amide bond contained in the polyamide-based resin contained in the optical film. And that the respective positions of the D ₁ ~ D ₃ as measured by the Raman spectroscopy of the maximum peak intensity of 1,550 ~ within the range of 1,650 cm ^-1 of the opposite showing each position of the optical film of the D ₁ ~ D ₃ The amount of polyamide resin. Thus, for example, in the above formula _{(1) I 1 / I 2} ≦ 0.97 I represents the intensity of _an intensity I less than a specific ratio of _2, which means, showing the position of the intensity I D of _a polyamide based on the ₁ The amount of the resin is less than the amount of the polyamide-based resin at the position D _{2 that exhibits the strength I 2 by a specific ratio. Similarly, I 3} /I ₂ ≦0.97 in the above formula (2) means that the amount of polyamide resin at the position D ₃ exhibiting the strength I ₃ is less than the position _{exhibiting the strength I 2 by a specific ratio} The amount of polyamide resin on D _2. Here, regarding the positions of the positions D ₀ to D ₃ , as described above, when an arbitrary position on one surface of the optical film is D ₀ , and the thickness of the optical film is A μm, the distance from _{D 0 in the thickness direction} A × 1/4 μm of the position D _1, the thickness direction D ₀ distance A × 1/2 μm of the position D _2, the thickness direction D ₀ distance A × 3/4 μm of position D _3. Therefore, the optical film satisfies at least one of the above-mentioned formulas (1) and (2), and the thickness direction is _{separated from the position D 0} on the surface by A×1/4 μm and/or A×3/4 μm ( the amount of the polyamide resin is present on the _{D. 1} and / or _{D. 3)} at a specific ratio of the thickness direction than the position of the upper surface distance D ₀ A × 1/2 μm of the position D of the polyamide resin ₂ The amount of part.

When an optical film containing a polyamide-based resin satisfies at least one of the above formula (1) and formula (2), the reason for the improvement of the bending resistance and elastic modulus of the optical film is not clear, but it is considered that the position D ₁ and when the case of small amount of polyamide resin is present on the portion of the / or D _3, the presence of other components other than the polyamide-based resin part, such as solvents and the like. Therefore, it is considered that the position D ₁ and/or D ₃ has a smaller amount of resin than, for example, the position D ₂ , and further includes components other than the resin such as a solvent, resulting in more flexibility. It is considered that the optical film includes a layer having flexibility in a part of the thickness region, and as a result, the physical strength of the optical film can be maintained and the bending resistance can be improved. In addition, it is considered that the layer having flexibility exists only in a part of the region, thereby enabling the entire optical film to have both high bending resistance and high elastic modulus.

As a method for measuring the intensity of the largest peak in the range of ^{1,550-1,650 cm -1} measured by Raman spectroscopy at each position of _{D 1} to D _{3, a method using a confocal Raman microscope can be cited.} Specifically, after focusing the confocal Raman microscope on the surface of the optical film of the present invention, measurement is performed at regular intervals in the thickness direction until it reaches the other surface. Then, the thickness of the optical film (A μm) is obtained from the obtained results, and based on the measurement results at the positions corresponding to the thickness of A×1/4 μm, A×2/4 μm, and A×3/4 μm, 1,550 The intensity of the largest peak in the range of ~1,650 cm ^-1. As the measurement conditions of Raman spectroscopy, for example, the conditions described in the examples can be used.

_{At least one of I 1} /I ₂ and I ₃ /I ₂ measured in the above manner is 0.97 or less. When both I ₁ /I ₂ and I ₃ /I ₂ exceed 0.97, sufficient bending resistance and elastic modulus cannot be obtained. Furthermore, I ₁ /I ₂ and I ₃ /I ₂ may both be 0.97 or less, but from the viewpoint that it is easy to further increase the strength of the optical film, it is preferably any of I ₁ /I ₂ and I ₃ /I ₂ One is 0.97 or less. At least one of I ₁ /I ₂ and I ₃ /I ₂ is preferably 0.95 or less, more preferably 0.93 or less, still more preferably 0.92 or less, still more preferably 0.8 or less, particularly preferably 0.6 or less, especially more preferably It is 0.5 or less. _{In addition, the lower limits of I 1} /I ₂ and I ₃ /I ₂ measured in the above-mentioned manner are not particularly limited. From the viewpoint that it is easy to sufficiently increase the strength of the optical film, it satisfies the I ₁ /I of the above formula (1) _{2 and/or I 3} /I _{2 that} satisfies the above formula (2) is preferably 0.3 or more, more preferably 0.35 or more, still more preferably 0.40 or more, and still more preferably 0.45 or more.

In the optical film, as long as a film with the above-mentioned characteristics can be obtained, _{the method of adjusting I 1} /I ₂ or I ₃ /I ₂ to the above-mentioned range is not particularly limited. Examples include: varnishes used in the production of optical films The type and amount of solvents used in the optical film, the drying conditions when manufacturing the optical film, the tentering conditions and other optical film manufacturing conditions are adjusted. Specifically, when manufacturing an optical film, the following steps are performed: the polyamide resin is dissolved in a solvent, and the resin solution (varnish) thus obtained is coated on the substrate and dried. The film peels off, but when the resin solution is applied to the substrate and allowed to dry, the solvent contained in the varnish will volatilize from the surface of the coating film on the opposite side of the substrate side that is in contact with the air . Therefore, the surface side of the coating film can be said to be in an environment where the solvent is volatile. On the other hand, the solvent is not easy to volatilize from the substrate side surface of the coating film. If the substrate is then peeled off, the solvent will also volatilize from the surface of the substrate. Moreover, it is considered that depending on the manufacturing conditions of the optical film, when the thickness of the optical film is set to 1, the position 1/4 in the thickness direction from the surface of the obtained optical film that is in contact with the substrate is the least likely to be dried. The remaining part of the solvent is not volatilized. By the method as described above, a portion where the solvent does not volatilize but remains at a position 1/4 in the thickness direction from the surface of the optical film that is in contact with the substrate is obtained, thereby satisfying the above equations (1) and (2). ) At least one of the optical film. _{The I 1} /I ₂ and/or I ₃ /I _{2 can be} adjusted to the above range by adjusting the manufacturing conditions of the optical film, especially the drying conditions, so as to form the layer as described above.

The substrate used to manufacture the optical film is usually peeled from the optical film. Therefore, sometimes it is not clear which surface of the optical film is the surface that is in contact with the substrate, but considering the above mechanism, the position of the D _0- based optical film on the surface that is in contact with the substrate is preferred, and the optical film Satisfy formula (1). As a method of judging which surface of the optical film is in contact with the substrate, for example, the surface roughness can be cited. For example, the surface roughness of both sides of the optical film can be measured by an interference microscope, and the surface with the lower value is set to The surface where the substrate meets. In addition, regarding an optical film satisfying either formula (1) and formula (2), when formula (1) is satisfied, it is determined that _{the surface close to D 1} (the surface having D ₀ ) is in contact with the substrate When the surface of D3 satisfies the formula (2), it is judged that _{the surface close to D 3} (the surface opposite to the surface with D ₀ ) is the surface that is in contact with the substrate.

In one embodiment of the present invention, the total light transmittance of the optical film is preferably 80% or more, more preferably 83% or more, still more preferably 85% or more, still more preferably 88% or more, and particularly preferably 89 % Or more, more preferably 90% or more. If the total light transmittance is equal to or greater than the above lower limit, the visibility of the optical film can be easily improved, especially when the optical film is assembled as a front panel in an image display device. The optical film of the present invention generally exhibits a higher total light transmittance, and therefore, compared with the case of using a film with a lower transmittance, it is possible to suppress the luminous intensity of display elements and the like required to obtain a certain brightness. Therefore, power consumption can be reduced. For example, when the optical film of the present invention is assembled in an image display device, even if the amount of light of the backlight device is reduced, a bright display tends to be obtained, which can help to save energy. The upper limit of total light transmittance is usually below 100%. Furthermore, the total light transmittance can be measured using a haze computer in accordance with JIS K 7105:1981 or JIS K 7361-1:1997, for example. In addition, the total light transmittance may be the total light transmittance within the thickness range of the following optical film.

In one embodiment of the present invention, the haze of the optical film is preferably 3% or less, more preferably 2.5% or less, still more preferably 1.5% or less, still more preferably 1.0% or less, particularly preferably 0.5% or less , Especially more preferably 0.2% or less. If the haze of the optical film is less than or equal to the above upper limit, it is easy to improve the visibility when the optical film is assembled in an image display device especially as a front panel. In addition, the lower limit of the haze is usually 0.01% or more. Furthermore, the haze can be measured using a haze computer in accordance with JIS K 7105:1981 or JIS K 7136:2000.

In one embodiment of the present invention, the yellowness (YI value) of the optical film is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.2 or less. If the yellowness of the optical film is less than the above upper limit, the transparency is good, and when used in the case of a front panel of an image display device, it can contribute to obtaining higher visibility. In addition, the yellowness is preferably -5 or more, more preferably -2 or more. Furthermore, regarding the yellowness (YI value), the transmittance of light from 300 to 800 nm can be measured using an ultraviolet-visible-near-infrared spectrophotometer to obtain the tristimulus value (X, Y, Z), and based on YI=100 ×(1.2769X-1.0592Z)/Y is calculated.

In one embodiment of the present invention, the elastic modulus of the optical film is preferably 5.3 GPa or more, more preferably 5.5 GPa or more, still more preferably 5.7 GPa or more, still more preferably 5.9 GPa or more, particularly preferably 6.0 GPa Above, it is usually 100 GPa or less. The modulus of elasticity can be measured using a tensile testing machine (for example, the distance between the chucks is 50 mm, and the tensile speed is 10 mm/min). For example, it can be measured by the method described in the examples.

From the viewpoint of easily improving the transparency and visibility of the optical film, the brightness L ^* value of the optical film of the present invention is preferably 90 or more, more preferably 93 or more, more preferably 95 or more, and usually 100 or less . The above-mentioned brightness L ^* value can be measured using a spectrophotometer. Specifically, a spectrophotometer can be used to measure the background without a sample, then set the optical film in the sample holder, and measure the transmittance of light with a wavelength of 300 to 800 nm.

The thickness of the optical film of the present invention is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 25 μm or more, still more preferably 30 μm or more, and preferably 100 μm or less, more preferably 80 μm Hereinafter, it is more preferably 60 μm or less, and it may be a combination of the upper and lower limits. If the thickness of the optical film is within the above range, it is easy to further improve the impact resistance of the optical film. In addition, the thickness of the optical film can be measured using a micrometer, for example, it can be measured by the method described in an Example.

The number of bending (bending radius R=1 mm) of the optical film of the present invention in the bending resistance test is preferably 20,000 or more, more preferably 22,000 or more, and still more preferably 24,000 or more. If the number of bending is more than the above lower limit, it has sufficient bending resistance as a front panel material such as a flexible display device. Furthermore, the number of bending in the bending resistance test of the present invention means that when the optical film is repeatedly bent (in both front and back directions) using a bending test machine under the condition of a bending radius (radius of curvature) R of 1 mm, to The number of reciprocating bending times up to the point when the film ruptures (set 1 reciprocating as 1 time) can be measured by the method described in the examples, for example.

＜Polyamide resin＞ The optical film of the present invention contains a polyamide resin. The polyamide resin contained in the optical film is not particularly limited as long as it contains at least a repeating structural unit containing an amide group. For example, it may be at least one polymer selected from the group consisting of the following polymers: Polymers containing repeating structural units of amide groups (hereinafter, also referred to as polyamide resins); and polymers containing both repeating structural units including amide groups and repeating structural units including amide groups (hereinafter , Also known as polyimide resin). The optical film may contain one type of polyamide resin, or two or more types of polyamide resin. From the viewpoint of film-forming properties, the polyamide resin contained in the base layer is preferably a polyamide resin.

[式(2)中，Z及X相互獨立地表示二價有機基，*表示鍵結鍵] [化2]

[式(1)中，Y表示四價有機基，X表示二價有機基，*表示鍵結鍵] 就成膜性、透明性及耐彎曲性之觀點而言，聚醯胺系樹脂較佳為具有式(1)所表示之結構單元及式(2)所表示之結構單元之聚醯胺醯亞胺樹脂。以下，對式(1)及式(2)進行說明，式(2)之相關說明係關於聚醯胺樹脂及聚醯胺醯亞胺樹脂兩者(聚醯胺系樹脂)，式(1)之相關說明係關於聚醯胺醯亞胺樹脂。In one embodiment of the present invention, the polyamide resin is a polyamide resin having a structural unit represented by the formula (2), or a structural unit represented by the formula (1) and represented by the above formula (2) The structural unit of polyamide imine resin. [化1]

[In formula (2), Z and X independently represent a divalent organic group, and * represents a bonding bond] [化2]

[In formula (1), Y represents a tetravalent organic group, X represents a divalent organic group, and * represents a bonding bond] From the viewpoints of film formation, transparency and bending resistance, polyamide resins are preferred It is a polyamide resin having a structural unit represented by formula (1) and a structural unit represented by formula (2). Hereinafter, the formula (1) and formula (2) will be described. The related description of formula (2) is about both polyamide resin and polyimide resin (polyamide resin), formula (1) The relevant description is about polyamide imide resin.

The structural unit represented by formula (2) is a structural unit formed by the reaction between a dicarboxylic acid compound and a diamine compound, and the structural unit represented by formula (1) is a structure formed by the reaction between a tetracarboxylic acid compound and a diamine compound unit.

[式(20)～式(29)中，W¹ 表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-Ar-、-SO₂ -、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂ -Ar-、-Ar-C(CH₃ )₂ -Ar-或-Ar-SO₂ -Ar-，其中，Ar相互獨立地表示氫原子可被取代為氟原子之碳數6～20之伸芳基(例如伸苯基)，*表示鍵結鍵] 作為Z之雜環結構，可列舉具有噻吩環骨架之基。就容易抑制光學積層體之黃度(降低YI值)之觀點而言，較佳為式(20)～式(29)所表示之基、及具有噻吩環骨架之基，更佳為式(26)、式(28)及式(29)所表示之基。In formula (2), Z represents a divalent organic group, and preferably represents an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons (such The hydrogen atom in the group may be substituted with a halogen atom (preferably a fluorine atom). A divalent organic group with 4 to 40 carbon atoms, more preferably an alkyl group with 1 to 6 carbon atoms, and a carbon number of 1 ～6 alkoxy group, or aryl group with 6-12 carbons (the hydrogen atoms in these groups may be substituted with halogen atoms (preferably fluorine atoms)) substituted with cyclic structure and carbon number 4-40 The bivalent organic base. Furthermore, as examples of alkyl groups having 1 to 6 carbons, alkoxy groups having 1 to 6 carbons, or aryl groups having 6 to 12 carbons, the relationship between R ^3a and R ^{3b in} the following formula (3) The exemplification also applies. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. As the organic group of Z, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) A group in which two non-adjacent bonding bonds of the group represented by the formula (29) are substituted with hydrogen atoms, and a divalent chain hydrocarbon group with 6 or less carbon atoms. [化3]

[In formulas (20) to (29), W ¹ 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-, where Ar independently represents an aryl group with 6 to 20 carbon atoms (such as benzene Group), * represents a bonding bond] Examples of the heterocyclic structure of Z include groups having a thiophene ring skeleton. From the viewpoint of easily suppressing the yellowness of the optical laminate (reducing the YI value), the group represented by the formulas (20) to (29) and the group having a thiophene ring skeleton are more preferred, and the formula (26) ), formula (28) and formula (29).

[式(20')～式(29')中，W¹ 及*如式(20)～式(29)中所定義] 再者，式(20)～式(29)及式(20')～式(29')中之環上之氫原子可被取代為碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基(該等基中之氫原子可被取代為鹵素原子(較佳為氟原子)取代)。As the organic group of Z, it is more preferably formula (20'), formula (21'), formula (22'), formula (23'), formula (24'), formula (25'), formula (26') , Formula (27'), formula (28') and formula (29') represented by the divalent organic group. [化4]

[In formulas (20') to (29'), W ¹ and * are as defined in formulas (20) to (29)] Furthermore, formulas (20) to (29) and (20') ~The hydrogen atom on the ring in formula (29') may be substituted with an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons (in these groups The hydrogen atom can be substituted with a halogen atom (preferably a fluorine atom)).

[式(d1)中，R²⁴ 係針對下述式(3)中之R^3a 所定義之基或氫原子，R²⁵ 表示R²⁴ 或-C(=O)-*，*表示鍵結鍵] 作為結構單元(d1)，具體而言，可列舉：R²⁴ 及R²⁵ 均為氫原子之結構單元(源自二羧酸化合物之結構單元)；R²⁴ 均為氫原子且R²⁵ 表示-C(=O)-*之結構單元(源自三羧酸化合物之結構單元)等。When the polyamide resin has a structural unit represented by any of the above formulas (20') to (29') in the formula (2), Z in the formula (2) is in particular In the case of the structural unit represented by the following formula (3'), from the viewpoint that it is easy to improve the film-forming properties of the varnish and the uniformity of the optical film, it is preferable that in addition to the structural unit, a polyamide-based The resin further has a carboxylic acid-derived structural unit represented by the following formula (d1). [化5]

[In formula (d1), R ²⁴ is the group or hydrogen atom defined ^{by R 3a} in the following formula (3) ^{, R 25} represents R ²⁴ or -C(=O)-*, * represents a bonding bond] As the structural unit (d1), specifically, a structural unit in which R ²⁴ and R ²⁵ are both hydrogen atoms (a structural unit derived from a dicarboxylic acid compound); R ²⁴ is a hydrogen atom and R ²⁵ represents -C (=O)-*The structural unit (the structural unit derived from the tricarboxylic acid compound) and so on.

[式(3)中，R^3a 及R^3b 相互獨立地表示碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，R^3a 及R^3b 中所包含之氫原子可相互獨立地被取代為鹵素原子，W相互獨立地表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-SO₂ -、-S-、-CO-或-N(R⁹ )-，R⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之一價烴基，s係0～4之整數，t係0～4之整數，u係0～4之整數，*表示鍵結鍵] [化7]

[式(3')中，R^3a 、R^3b 、s、t、u、W及*如式(3)中所定義] 再者，於本說明書中，聚醯胺系樹脂具有式(2)中之Z由式(3)所表示之結構單元、及聚醯胺系樹脂具有式(3)所表示之結構作為式(2)中之Z含義相同，意指聚醯胺系樹脂中所包含之複數個式(2)所表示之結構單元中之至少一部分結構單元中之Z由式(3)所表示。該記載亦適用於其他相同之記載。The polyamide-based resin may include a plurality of types of Z as Z in the formula (2), and the plurality of types of Z may be the same or different from each other. Especially from the viewpoint of easily improving the bending resistance and impact resistance of the optical film of the present invention, and easily improving the optical properties, the polyamide resin preferably has at least the following structural units, namely Z in formula (2) It is preferably a structural unit represented by formula (3), more preferably a formula (3'). [化6]

[In formula (3), R ^3a and R ^3b independently represent an alkyl group having 1 to 6 carbons, an alkoxy group having 1 to 6 carbons, or an aryl group having 6 to 12 carbons, R ^3a and R ^3b The hydrogen atoms contained in can be independently substituted with halogen atoms, and W independently represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-,- C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ⁹ )-, R ⁹ represents a hydrogen atom, which can be substituted by a halogen atom A monovalent hydrocarbon group with 1 to 12 carbon atoms, s is an integer from 0 to 4, t is an integer from 0 to 4, u is an integer from 0 to 4, * represents a bonding bond] [化7]

[In the formula (3'), R ^3a , R ^3b , s, t, u, W, and * are as defined in the formula (3)] Furthermore, in this specification, the polyamide resin has the formula (2) The Z in the formula (3) is a structural unit represented by the formula (3), and the polyamide resin has the structure represented by the formula (3). As Z in the formula (2) has the same meaning, it means that the polyamide resin contains Z in at least a part of the structural units represented by formula (2) is represented by formula (3). This record also applies to other similar records.

In formula (3) and formula (3'), W independently represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ⁹ )-, from the viewpoint of the bending resistance of the optical laminate, preferably It represents -O- or -S-, and more preferably represents -O-. R ^3a and R ^3b independently represent an alkyl group having 1 to 6 carbons, an alkoxy group having 1 to 6 carbons, or an aryl group having 6 to 12 carbons. Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, and 2-methyl. -Butyl, 3-methylbutyl, 2-ethyl-propyl, n-hexyl, etc. Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tertiary butoxy, and pentoxy. , Hexyloxy, cyclohexyloxy, etc. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. From the viewpoint of surface hardness and flexibility of the optical laminate, R ^3a and R ^3b preferably independently represent an alkyl group having 1 to 6 carbon atoms, and more preferably represent an alkyl group having 1 to 3 carbon atoms. Here, ^{the hydrogen atoms contained in R 3a} and R ^3b may be substituted with halogen atoms independently of each other. R ⁹ represents a hydrogen atom, a monovalent hydrocarbon group of 1 to 12 carbons which may be substituted with a halogen atom. Examples of monovalent hydrocarbon groups with 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2-methyl Base-butyl, 3-methylbutyl, 2-ethyl-propyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl, n-decyl, etc., which can be halogenated Atom substitution. As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.

In formula (3) and formula (3′), t and u are independently an integer of 0-4, preferably an integer of 0-2, more preferably 0 or 1, and still more preferably 0.

In formula (3) and formula (3'), s is an integer in the range of 0-4. If s is in this range, it is easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film. From the viewpoint that it is easy to further improve the impact resistance, elastic modulus and bending resistance of the optical film, s in formula (3) and formula (3') is preferably an integer in the range of 0 to 3, more preferably It is an integer in the range of 0-2, more preferably 0 or 1, and still more preferably 0. The structure represented by formula (3) or formula (3') in which s is 0 as the structural unit of Z in formula (2) is, for example, a structural unit derived from terephthalic acid or isophthalic acid, and the structural unit Particularly preferred is a structural unit comprising a structure in which s is 0 and u is 0 in formula (3) or formula (3′). From the viewpoint of easily improving the impact resistance, elastic modulus, and bending resistance of the optical film, the polyamide-based resin preferably contains a structural unit derived from terephthalic acid. The polyamide-based resin may include one or two or more types of Z structural units represented by formula (3) or formula (3'). From the viewpoint of improving the impact resistance, elastic modulus and bending resistance of the optical film, and reducing the yellowness (YI value), the polyamide resin preferably contains the formula (3) or the formula (3') Two or more structures with different values of s preferably include two or three structures with different values of s in formula (3) or formula (3') as Z in formula (2). In this case, from the viewpoints of easily improving the impact resistance, elastic modulus, and bending resistance of the optical film, and the viewpoint of easily reducing the yellowness (YI value) of the optical film, polyamide resins are more preferable It contains the structure represented by formula (3) where s is 0 as Z in the structural unit represented by formula (2), in addition to the structural unit containing the structure, it further contains the structure represented by formula (3) containing s as 1 The structural unit of the structure. Furthermore, it is also preferable to have a structural unit represented by the above-mentioned formula (d1) in addition to the structural unit represented by the formula (2) having Z represented by the formula (3) where s is 0.

於此情形時，容易提高光學膜之耐衝擊性、彈性模數及耐彎曲性，並且容易降低黃度。In a preferred embodiment of the present invention, the polyamide resin has a structure with s=0 and u=0 as the structure (divalent group) represented by formula (3) or formula (3'). In a more preferable embodiment of the present invention, the polyamide resin has a structure with s=0 and u=0, and the structure represented by formula (3") is represented by formula (3) or formula (3')的结构。 [化8]

In this case, it is easy to improve the impact resistance, elastic modulus and bending resistance of the optical film, and it is easy to reduce the yellowness.

When the polyamide resin has the structural unit represented by formula (3) or formula (3') in the formula (2), the structural unit represented by formula (1) of the polyamide resin When the total of the structural units represented by formula (2) is set to 100 mol%, the ratio is preferably 20 mol% or more, more preferably 30 mol% or more, and still more preferably 40 mol% or more, More preferably, it is 50 mol% or more, particularly preferably 60 mol% or more, more preferably 90 mol% or less, more preferably 85 mol% or less, and still more preferably 80 mol% or less. If Z in formula (2) is represented by formula (3) or formula (3'), the ratio of the structural unit is more than the above lower limit, it is easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film. If Z in formula (2) is represented by formula (3) or formula (3'), the ratio of structural units represented by formula (3) or formula (3') is less than the above upper limit, it is easy to suppress the hydrogen bond between amide bonds derived from formula (3) The viscosity of the resin-containing varnish increases, thereby improving the processability of the film.

In addition, when the polyamide resin has a structure represented by formula (3) or formula (3') with s=1 to 4 as Z in formula (2), the formula ( 1) When the total of the structural unit represented by the formula (2) and the structural unit represented by the formula (2) is set to 100 mol%, the formula having the formula (3) represented by the formula (3) or the formula (3') where s is 1 to 4 (2) The ratio of the structural unit represented is preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 7 mol% or more, still more preferably 9 mol% or more, more preferably It is 90 mol% or less, more preferably 70 mol% or less, still more preferably 50 mol% or less, and still more preferably 30 mol% or less. If the ratio of the structural unit represented by the formula (2) having the formula (3) represented by the formula (3) or the formula (3') where s is 1 to 4 is more than the above lower limit, the chemical stability and resistance of the optical film will be easily improved. Impact, elastic modulus and bending resistance. If the ratio of the structural unit represented by the formula (2) having Z represented by the formula (3) in which s is 1 to 4 is below the above upper limit, it is easy to suppress the expression derived from the formula (3) or the formula (3') The viscosity of the resin-containing varnish increases due to the hydrogen bonds between the amide bonds of the structure, thereby improving the processability of the film. Furthermore, the ratio of Z in formula (1), formula (2), and formula (2) in the structural unit represented by formula (3) or formula (3') can be, for example, ¹ H-NMR (nuclear magnetic resonance, Nuclear magnetic resonance) for measurement, or it can be calculated based on the addition ratio of raw materials.

In a preferred embodiment of the present invention, Z represented by formula (3) or formula (3') in which s in the polyamide-based resin is 0-4 is preferably 30 mol% or more, more preferably 40 mol% or more, more preferably 45 mol% or more, and still more preferably 50 mol% or more. If Z represented by formula (3) or formula (3') in which s is 0 to 4 is more than the above lower limit, it is easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film. In addition, as long as s in the polyamide-based resin is 0 to 4, Z represented by formula (3) or formula (3') is 100 mol% or less. Furthermore, the ratio of the structural unit represented by formula (2) having s of 0-4 or Z represented by formula (3') in the resin can ^{be measured by 1} H-NMR, or It can also be calculated based on the addition ratio of the raw materials.

In a preferred embodiment of the present invention, Z represented by formula (3) or formula (3') in which s in the polyamide resin is 1 to 4 is preferably 5 mol% or more, more preferably 8 mol% or more, more preferably 10 mol% or more, and still more preferably 12 mol% or more. When the formula (3) or formula (3') represented by the formula (3) or formula (3') where the polyamide resin s is 1 to 4 is above the above lower limit, it is easy to improve the impact resistance, elastic modulus and bending resistance of the optical film Sex. In addition, Z represented by formula (3) or formula (3') in which s is 1 to 4 is preferably 90 mol% or less, more preferably 70 mol% or less, and still more preferably 50 mol% or less, More preferably, it is 30 mol% or less. When Z represented by formula (3) or formula (3') where s is 1 to 4 is below the above upper limit, it is easy to suppress the expression derived from formula (3) or formula (3') where s is 1 to 4 The viscosity of the resin-containing varnish increases due to the hydrogen bonding between the amide bonds of the structure shown, thereby improving the processability of the film. Furthermore, the ratio of the structural unit represented by formula (2) having s of 1 to 4 in formula (3) or Z represented by formula (3') can ^{be measured by, for example, 1} H-NMR, or It can also be calculated based on the addition ratio of the raw materials.

In formula (1) and formula (2), X independently represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbons, and more preferably two having a cyclic structure having 4 to 40 carbons Valence organic base. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. Regarding the above-mentioned organic group, the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. In this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1-8. In one embodiment of the present invention, the polyamide resin of the present invention may include a plurality of types of X, and the plurality of types of X may be the same or different from each other. Examples of X include: formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17), and formula (18) The group represented by the formula (10) to the formula (18) wherein the hydrogen atom in the group represented by the formula (10) to the formula (18) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a carbon number of 6 or less The chain hydrocarbon group.

[化9]

In formulas (10) to (18), * represents a bonding bond, V ¹ , V ² and V ³ independently represent a single bond, -O-, -S-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -CO- or -N(Q)-. Wherein, Q represents a monovalent hydrocarbon group with 1 to 12 carbons which may be substituted by a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include the groups described ^{above for R 9.} In one example, V ¹ and V ³ are single bonds, -O- or -S-, and V ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -or -SO ₂ -. The bonding positions of V ¹ and V ² and each ring, and the bonding positions of V ² and V ³ and each ring are independently of each other, preferably meta-position or para-position, and more preferably para-position.

Among the bases represented by formulas (10) to (18), from the viewpoint of easily improving the chemical stability, impact resistance, elastic modulus, and bending resistance of the optical film, formulas (13), The groups represented by formula (14), formula (15), formula (16) and formula (17) are more preferably groups represented by formula (14), formula (15) and formula (16). In addition, from the viewpoint of easily improving the impact resistance, elastic modulus, and flexibility of the optical film, V ¹ , V ² and V ³ are preferably single bonds, -O- or -S- independently of each other, and more preferably It is a single bond or -O-.

[式(4)中，R¹⁰ ～R¹⁷ 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，R¹⁰ ～R¹⁷ 中所包含之氫原子可相互獨立地被取代為鹵素原子，*表示鍵結鍵] 若式(1)及式(2)所表示之複數個結構單元中之X之至少一部分係式(4)所表示之結構，則容易提高光學膜之化學穩定性、耐衝擊性、彈性模數及透明性。In a preferred embodiment of the present invention, the polyamide resin contains the structure represented by formula (4) as X in formula (1) or X in formula (2). [化10]

[In formula (4), R ¹⁰ to R ¹⁷ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, R ¹⁰ The hydrogen atoms contained in ~R ¹⁷ can be substituted with halogen atoms independently of each other, * represents a bonding bond] If at least a part of X in the plural structural units represented by formula (1) and formula (2) is represented by formula The structure shown in (4) can easily improve the chemical stability, impact resistance, elastic modulus and transparency of the optical film.

In formula (4), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons, and a carbon number of 1 to 6 The alkoxy group, or the aryl group with 6-12 carbons. Examples of alkyl groups having 1 to 6 carbons, alkoxy groups having 1 to 6 carbons, or aryl groups having 6 to 12 carbons include alkyl groups having 1 to 6 carbons in formula (3), and carbon number 1. The group exemplified by the alkoxy group of ~6 or the aryl group of 6-12 carbon atoms. Preferably, R ¹⁰ to R ¹⁷ independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹⁰ to R ¹⁷ include The hydrogen atoms can be substituted with halogen atoms independently of each other. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example. From the viewpoints of impact resistance, elastic modulus, transparency, and bending resistance of the optical film, R ¹⁰ to R ¹⁷ further preferably independently represent a hydrogen atom, a methyl group, a fluoro group, a chloro group, or Trifluoromethyl, more preferably R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ represent a hydrogen atom, and R ¹¹ and R ¹⁷ represent a hydrogen atom, a methyl group, a fluoro group, a chloro group or Trifluoromethyl, particularly preferably, R ¹¹ and R ¹⁷ represent methyl or trifluoromethyl.

於此情形時，藉由含有氟元素之骨架而提高聚醯胺系樹脂於溶劑中之溶解性，容易提高含有該樹脂之清漆之保管穩定性，並且容易降低該清漆之黏度，容易提高光學膜之加工性。又，藉由含有氟元素之骨架，容易提高光學膜之光學特性。In a preferred embodiment of the present invention, the structural unit represented by formula (4) is the structural unit represented by formula (4'), that is, multiple structural units represented by formula (1) and formula (2) At least a part of X in it is a structural unit represented by formula (4'). [化11]

In this case, the solubility of the polyamide resin in the solvent is improved by the skeleton containing the fluorine element, and the storage stability of the varnish containing the resin is easily improved, and the viscosity of the varnish is easily reduced, and the optical film is easily improved. The processability. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film.

In a preferred embodiment of the present invention, X in the polyamide resin is preferably 30 mol% or more, more preferably 50 mol% or more, and more preferably 70 mol% or more. (4) Especially expressed by formula (4'). When X in the above-mentioned range in the polyamide-based resin is represented by formula (4), especially formula (4'), the obtained optical film contains a fluorine element skeleton, which is easy to improve the resin's solvent The solubility of the resin is easy to improve the storage stability of the varnish containing the resin, and it is easy to reduce the viscosity of the varnish, and it is easy to improve the processability of the optical film. In addition, it is easy to improve the optical properties of the optical film by the skeleton containing the fluorine element. Furthermore, it is preferable that 100 mol% or less of X in the polyamide resin is represented by formula (4), especially formula (4′). X in the above resin may be formula (4), especially formula (4'). The ratio of the structural unit represented by the formula (4) of X in the above resin can ^{be measured, for example, by 1} H-NMR, or can also be calculated based on the addition ratio of the raw materials.

In the formula (1), Y represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbons, and more preferably a tetravalent organic group having 4 to 40 carbons having a cyclic structure. Examples of the cyclic structure include an alicyclic ring, an aromatic ring, and a heterocyclic structure. From the viewpoint of easy improvement in impact resistance and elastic modulus, an aromatic ring is preferably used. The above-mentioned organic group is an organic group in which the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. In this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1-8. In one embodiment of the present invention, the polyamide-based resin is a polyamide-imide resin, and the polyamide-imide resin may include a plurality of types of Y, and the plurality of types of Y may be the same or different from each other. As Y, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) and the group represented by the formula (29); the hydrogen atom in the group represented by the formula (20) ~ formula (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group The group; and a tetravalent chain hydrocarbon group with a carbon number of 6 or less.

[化12]

In formulas (20) to (29), * represents a bonding bond, W ¹ 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 an arylene group having 6 to 20 carbon atoms in which a hydrogen atom can be substituted with a fluorine atom, and a specific example includes a phenylene group.

Among the bases represented by formulas (20) to (29), from the viewpoint of easily improving the chemical stability, impact resistance, elastic modulus, and bending resistance of the optical film, formulas (26), The group represented by formula (28) or formula (29) is more preferably the group represented by formula (26). In addition, from the viewpoint of easily improving the chemical stability, impact resistance, elastic modulus, and bending resistance of the optical film, and easily reducing the yellowness of the optical film, W ¹ is preferably a single bond, -O independently of each other. -, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -O- , -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -C(CH ₃ ) ₂ -or -C (CF ₃ ) ₂ -, more preferably a single bond or -C(CF ₃ ) ₂ -.

In a preferred embodiment of the present invention, Y in the polyimide imide resin is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more. Formula (26) expressed. If Y in the above-mentioned range in the polyamide imide resin is represented by formula (26), preferably W ¹ is a single bond, -C(CH ₃ ) ₂ -or -C(CF ₃ ) _2- 26). More preferably, W ¹ is a single bond or -C(CF ₃ ) ₂ -represented by formula (26), which is easy to improve the chemical stability, impact resistance, elastic modulus and bending resistance of the optical film. And it is easy to reduce the yellowness of the optical film. The ratio of the structural unit represented by formula (26) of Y in the polyamide imide resin can ^{be measured, for example, by 1} H-NMR, or can also be calculated based on the addition ratio of the raw materials.

[式(5)中，R¹⁸ ～R²⁵ 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，R¹⁸ ～R²⁵ 中所包含之氫原子可相互獨立地被取代為鹵素原子，*表示鍵結鍵] [化14]

[式(9)中，R³⁵ ～R⁴⁰ 相互獨立地表示氫原子、碳數1～6之烷基、或碳數6～12之芳基，R³⁵ ～R⁴⁰ 中所包含之氫原子可相互獨立地被取代為鹵素原子，*表示鍵結鍵] 若複數個式(1)中之Y之至少一部分由式(5)所表示及/或由式(9)所表示，則容易提高光學膜之化學穩定性、耐衝擊性、彈性模數及光學特性。In a preferred embodiment of the present invention, at least a part of Y in a plurality of formulas (1) is represented by formulas (5) and/or formulas (9). [化13]

[In formula (5), R ¹⁸ to R ²⁵ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, R ¹⁸ ~ ^{The hydrogen atoms contained in R 25} can be independently substituted with halogen atoms, and * represents a bonding bond] [Chemical 14]

[In formula (9), R ³⁵ to R ⁴⁰ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons, or an aryl group having 6 to 12 carbons, and the hydrogen atoms contained in ^{R 35} to R ^{40 may be} They are substituted with halogen atoms independently of each other, * represents a bonding bond] If at least a part of Y in the formula (1) is represented by the formula (5) and/or is represented by the formula (9), it is easy to improve the optical The chemical stability, impact resistance, elastic modulus and optical properties of the film.

In formula (5), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons, and a carbon number of 1 to 6 The alkoxy group, or the aryl group with 6-12 carbons. Examples of alkyl groups having 1 to 6 carbons, alkoxy groups having 1 to 6 carbons, or aryl groups having 6 to 12 carbons include the alkyl groups having 1 to 6 carbons in the above formula (3), carbon An alkoxy group having 1 to 6 or an aryl group having 6 to 12 carbons is exemplified. R ¹⁸ to R ²⁵ preferably independently represent a hydrogen atom or an alkyl group having 1 to 6 carbons, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbons, wherein R ¹⁸ to R ²⁵ includes The hydrogen atoms can be substituted with halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoint of easy improvement of the impact resistance, elastic modulus, and bending resistance of the optical film, and the viewpoint of easy improvement of transparency and easy maintenance of the transparency, R ¹⁸ to R ²⁵ preferably represent hydrogen independently of each other. Atom, methyl group, fluoro group, chloro group or trifluoromethyl group, more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ represent hydrogen atom, and R ²¹ and R ²² represent hydrogen Atom, methyl group, fluoro group, chloro group or trifluoromethyl group, particularly preferably R ²¹ and R ²² represent a methyl group or a trifluoromethyl group.

In formula (9), from the viewpoints of easy improvement of the chemical stability, impact resistance, elastic modulus, and bending resistance of the optical film, and the viewpoints of easy improvement of transparency and easy maintenance of the transparency, R ³⁵ to R ⁴⁰ preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably represents a hydrogen atom. Among them, ^{the hydrogen atoms contained in R 35} to R ⁴⁰ may be independently substituted with halogen atoms. Examples of the halogen atom include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. As the alkyl group having 1 to 6 carbons and the aryl group having 6 to 12 carbons in ^{R 35} to R ^{40, those exemplified above can be cited, respectively.}

即，複數個Y之至少一部分由式(5')及/或式(9')所表示。於此情形時，容易提高光學膜之耐衝擊性、彈性模數及耐彎曲性。進而，於式(5)由式(5')所表示之情形時，藉由含有氟元素之骨架，容易提高聚醯胺醯亞胺樹脂於溶劑中之溶解性，容易提高含有該樹脂之清漆之保管穩定性，並且容易降低該清漆之黏度，容易提高光學膜之加工性。又，藉由含有氟元素之骨架，容易提高光學膜之光學特性。In a preferred embodiment of the present invention, formula (5) is represented by formula (5'), and formula (9) is represented by formula (9'). [化15]

That is, at least a part of a plurality of Y is represented by formula (5') and/or formula (9'). In this case, it is easy to improve the impact resistance, elastic modulus and bending resistance of the optical film. Furthermore, in the case where the formula (5) is represented by the formula (5'), by containing the fluorine element skeleton, the solubility of the polyimide resin in the solvent is easily improved, and the varnish containing the resin is easily improved The storage stability, and easy to reduce the viscosity of the varnish, easy to improve the processability of the optical film. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film.

In a preferred embodiment of the present invention, Y in the polyimide imide resin is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more. Formula (5), in particular, it is represented by Formula (5'). If Y in the above range in the polyimide resin is represented by formula (5), especially formula (5'), it is easy to improve the polyimide imide resin by the skeleton containing fluorine element Solubility in solvents can easily reduce the viscosity of varnishes containing the resin and improve the processability of optical films. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film. Furthermore, it is preferable that 100 mol% or less of Y in the polyimide resin is represented by formula (5), especially formula (5'). Y in the polyimide resin may be formula (5), especially formula (5'). The ratio of the structural unit represented by formula (5) of Y in the polyamide imide resin can ^{be measured by, for example, 1} H-NMR, or can be calculated based on the addition ratio of the raw materials.

In a preferred embodiment of the present invention, the plural structural units represented by formula (1) preferably include Y represented by formula (9) in addition to the structural unit represented by formula (5) Structural units. When the structural unit represented by formula (9) is further included in Y, it is easy to further improve the impact resistance and elastic modulus of the optical film.

The polyimide imine resin may include the structural unit represented by formula (30) and/or the structural unit represented by formula (31), in addition to formula (1) and optionally formula (2) In addition to the structural unit, the structural unit represented by the formula (30) and/or the structural unit represented by the formula (31) is also included. [化16]

In formula (30), Y ¹ represents a tetravalent organic group, preferably an organic group in which the hydrogen atom in the organic group can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Examples of Y ¹ include: formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) ) And the group represented by the formula (29); the hydrogen atom in the group represented by the formula (20) ~ formula (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group Group; and a tetravalent chain hydrocarbon group with a carbon number of 6 or less. In one embodiment of the present invention, the polyimide resin may include a plurality of Y ¹ , and the plurality of Y ¹ may be the same or different from each other.

In formula (31), Y ² represents a trivalent organic group, preferably an organic group in which the hydrogen atom in the organic group can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , the above formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) A group in which any one of the bonding bonds of the group represented by the formula (29) is substituted with a hydrogen atom; and a trivalent chain hydrocarbon group with 6 or less carbon atoms. In one embodiment of the present invention, the polyimide resin may include multiple types of Y ² , and the multiple types of Y ² may be the same or different from each other.

In formula (30) and formula (31), X ¹ and X ² independently represent a divalent organic group, and preferably represent an organic group in which a hydrogen atom in the organic group can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Examples of X ¹ and X ² include the above-mentioned formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), and formula (17) And the group represented by the formula (18); the hydrogen atom in the group represented by the formula (10) to the formula (18) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group ; And a chain hydrocarbon group with a carbon number of 6 or less.

In one embodiment of the present invention, the polyamide-based resin includes a structural unit represented by formula (1) and/or formula (2), and optionally a structure represented by formula (30) and/or formula (31) unit. In addition, from the viewpoint of easily improving the optical properties, impact resistance, elastic modulus, and bending resistance of the optical film, among the above-mentioned polyamide-based resins, formulas (1) and (2), and as appropriate All the structural units represented by (30) and formula (31) are based, and the ratio of structural units represented by formula (1) and formula (2) is preferably 80 mol% or more, more preferably 90 mol% or more , And more preferably 95 mol% or more. Furthermore, in the polyamide resin, based on all the structural units represented by formula (1) and formula (2), and as the case may be, formula (30) and/or formula (31), formula (1) and formula (2) The ratio of structural units indicated is usually 100% or less. In addition, the above-mentioned ratio can ^{be measured by 1} H-NMR, for example, or it can also be calculated based on the addition ratio of raw materials.

In one embodiment of the present invention, the content of the polyamide resin in the optical film relative to 100 parts by mass of the optical film is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass Parts or more, preferably 99.5 parts by mass or less, more preferably 95 parts by mass or less. If the content of the polyamide resin is within the above range, it is easy to improve the chemical stability, optical properties, impact resistance and elastic modulus of the optical film.

From the viewpoint of easily improving the chemical stability, impact resistance, elastic modulus, and bending resistance of the optical film, the weight average molecular weight of the polyamide resin is preferably 200,000 or more in terms of standard polystyrene, and more preferably 230,000 or more, more preferably 250,000 or more, still more preferably 270,000 or more, and particularly preferably 280,000 or more. In addition, from the viewpoint of easily improving the solubility of the resin in a solvent, and easily improving the extensibility and processability of the optical film, the weight average molecular weight of the polyamide-based resin is preferably 1,000,000 or less, more preferably 800,000 or less , More preferably 700,000 or less, and still more preferably 500,000 or less. The weight average molecular weight can be measured by, for example, GPC, and can be calculated by standard polystyrene conversion, and can be calculated, for example, by the method described in the examples. Furthermore, it is also possible to improve the bending resistance of the optical film by increasing the weight average molecular weight of the polyamide resin contained in the optical film. However, if the weight average molecular weight of the polyamide resin is too high, the optics will be impaired. For the processability of the film, for example, the physical properties and optical properties of the optical film are prone to deviations. The optical film of the present invention having the above-mentioned characteristics is easy to improve the bending resistance even when the weight average molecular weight of the polyamide resin contained in the optical film is relatively low, and therefore it is easy to further improve the physical properties of the optical film And the homogeneity of optical properties.

In a preferred embodiment of the present invention, when the polyamide resin is a polyamide resin, the content of the structural unit represented by formula (2) in the polyamide resin Relative to 1 mol of the structural unit represented by formula (1), it is preferably 0.1 mol or more, more preferably 0.5 mol or more, still more preferably 1.0 mol or more, and even more preferably 1.5 mol or more. It is preferably 6.0 mol or less, more preferably 5.0 mol or less, and still more preferably 4.5 mol or less. If the content of the structural unit represented by formula (2) is more than the above lower limit, it is easy to improve the impact resistance and elastic modulus of the optical film. Moreover, if the content of the structural unit represented by the formula (2) is below the above upper limit, it is easy to suppress the viscosity increase caused by the hydrogen bond between the amide bonds in the formula (2), thereby improving the processability of the optical film.

In a preferred embodiment of the present invention, the polyamide resin contained in the optical film may include, for example, halogen atoms such as fluorine atoms that can be introduced by the above-mentioned fluorine-containing substituents. When the polyamide resin contains halogen atoms, it is easy to increase the elastic modulus of the optical film and reduce the yellowness (YI value). If the elastic modulus of the optical film is high, it is easy to suppress the occurrence of damage and wrinkles. In addition, if the yellowness of the optical film is low, it is easy to improve the transparency and visibility of the film. The halogen atom is preferably a fluorine atom. As a preferable fluorine-containing substituent for making the polyimide resin contain a fluorine atom, a fluorine group and a trifluoromethyl group are mentioned, for example.

Based on the mass of the polyamide resin, the content of the halogen atom in the polyamide resin is preferably 1-40% by mass, more preferably 5-40% by mass, and still more preferably 5-30% by mass . If the content of halogen atoms is more than the above lower limit, it is easy to further increase the elastic modulus of the optical film, reduce the water absorption rate, further reduce the yellowness, and further improve the transparency and visibility. If the content of halogen atoms is less than the above upper limit, synthesis is easy.

The imidization rate of the polyimide resin is preferably 90% or more, more preferably 93% or more, and still more preferably 96% or more. From the viewpoint of easy improvement of the optical properties of the optical film, the imidization rate is preferably at least the above lower limit. In addition, the upper limit of the imidization rate is 100% or less. The imidization rate represents the ratio of the molar amount of the amide bond in the polyimide resin to the value of twice the molar amount of the structural unit derived from the tetracarboxylic acid compound. Furthermore, when the polyimide imide resin contains a tricarboxylic acid compound, the imidization rate means the molar amount of the imine bond in the polyimide imide resin relative to the polyimide imide resin. The ratio of the value of twice the molar amount of the structural unit derived from the tetracarboxylic acid compound to the total molar amount of the structural unit derived from the tricarboxylic acid compound in the amine resin. In addition, the imidization rate can be determined by IR (infrared spectroscopy) method, NMR method, or the like.

[式(3")中，R¹ ～R⁸ 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，R¹ ～R⁸ 中所包含之氫原子可相互獨立地被取代為鹵素原子， A表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-SO₂ -、-S-、-CO-或-N(R⁹ )-， R⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之一價烴基， m係0～4之整數， R³¹ 及R³² 相互獨立地表示羥基、甲氧基、乙氧基、正丙氧基、異丙氧基、正丁氧基、第二丁氧基、第三丁氧基或氯原子](Method for producing resin) Polyamide resin can be produced using, for example, a diamine compound and a dicarboxylic acid compound as main raw materials. Polyamide imide resins and polyamide imide precursor resins can be produced, for example, using tetracarboxylic acid compounds, dicarboxylic acid compounds, and diamine compounds as main raw materials. Among them, the dicarboxylic acid compound preferably contains at least The compound represented by formula (3"). [化17]

[In formula (3"), R ¹ to R ⁸ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, R ^{The hydrogen atoms contained in 1} to R ⁸ can be independently substituted with halogen atoms. A represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ⁹ )-, R ⁹ represents a hydrogen atom, which can be substituted by a halogen atom The monovalent hydrocarbon group with 1-12 carbon atoms, m is an integer of 0-4, R ³¹ and R ³² independently represent hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy, n-butyl Oxy group, second butoxy group, third butoxy group or chlorine atom]

In a preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by the formula (3") in which m is 0. As the dicarboxylic acid compound, it is more preferable to be a compound represented by the formula (3") in which m is 0 In addition to the compounds shown, a compound represented by formula (3") in which A is an oxygen atom is also used. In another preferred embodiment, the dicarboxylic acid compound is in formula (3" in which R ³¹ and R ³² are chlorine atoms ") represented by the compound. In addition, a diisocyanate compound may be used instead of the diamine compound.

Examples of the diamine compound used to produce the resin include aliphatic diamine, aromatic diamine, and mixtures thereof. Furthermore, in this embodiment, "aromatic diamine" means a diamine in which an amine group is directly bonded to an aromatic ring, and a part of its structure may include an aliphatic group or other substituents. The aromatic ring may be a monocyclic ring or a condensed ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a sulphur ring, but are not limited to them. Among them, a benzene ring is preferred. In addition, "aliphatic diamine" means a diamine in which an amine group and an aliphatic group are directly bonded, and a part of its structure may include an aromatic ring or other substituents.

As aliphatic diamines, for example, acyclic aliphatic diamines such as hexamethylene diamine; and 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl) Base) cyclohexane, noralkylene diamine and 4,4'-diamine dicyclohexylmethane and other cyclic aliphatic diamines. These etc. can be used individually or in combination of 2 or more types.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2 ,6-Diaminonaphthalene and other aromatic diamines with one aromatic ring; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diamine Diphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether Diphenyl ingot, 3,3'-diaminodiphenyl ingot, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, Bis[4-(4-aminophenoxy)phenyl]sulfur, bis[4-(3-aminophenoxy)phenyl]sulfur, 2,2-bis[4-(4-aminobenzene Oxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoro Methyl)-4,4'-diaminobiphenyl (sometimes referred to as TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-amino) Phenyl) sulphur, 9,9-bis(4-amino-3-methylphenyl) sulphur, 9,9-bis(4-amino-3-chlorophenyl) sulphur, 9,9-bis( Aromatic diamines having two or more aromatic rings, such as 4-amino-3-fluorophenyl) pyridine. These etc. can be used individually or in combination of 2 or more types.

Examples of aromatic diamines include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3, 3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy) Benzene, bis[4-(4-aminophenoxy)phenyl] ash, bis[4-(3-aminophenoxy)phenyl] ash, 2,2-bis[4-(4-amine Phenyloxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis( Trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, more preferably: 4,4'-bis Diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 1,4-bis(4 -Aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl] chrysene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2 ,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4,4'-bis(4-aminophenoxy) Base) Biphenyl. These etc. can be used individually or in combination of 2 or more types.

Among the above-mentioned diamine compounds, from the viewpoints of high elastic modulus, high transparency, high flexibility, high bending resistance and low colorability of the optical film, it is preferable to use aromatic diamine compounds selected from the group having a biphenyl structure. One or more of the group consisting of amines. More preferably, use selected from 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and At least one of the group consisting of 4,4'-diaminodiphenyl ether, and more preferably 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ( TFMB).

Examples of the tetracarboxylic acid compound used to produce the resin include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of two or more kinds. In addition to the dianhydride, the tetracarboxylic acid compound may also be a tetracarboxylic acid compound related product such as a chlorine compound.

Specific examples of aromatic tetracarboxylic dianhydrides include: non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides Acid dianhydride. Examples of non-condensed polycyclic aromatic tetracarboxylic dianhydrides include: 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid Dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3' -Biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl tetracarboxylic 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 Yl)diphthalic dianhydride (sometimes referred to as 6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxybenzene) Base) 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'-(terephthalic acid) dianhydride, 4,4 '-(Isophthalic dioxy)diphthalic dianhydride. In addition, examples of monocyclic aromatic tetracarboxylic dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of condensed polycyclic aromatic tetracarboxylic dianhydrides include 2,3,6,7-Naphthalenetetracarboxylic dianhydride.

Among them, can be preferably cited: 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3 '-Benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3, 3',4,4'-Diphenyl tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxybenzene) Base) propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA ), 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'-(terephthalic acid) dianhydride and 4,4'-(isophthalic acid) Anhydrides, more preferably: 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'- Biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), bis(3,4-dicarboxyphenyl)methane dianhydride and 4,4 '-(Terephthalenedioxy)diphthalic dianhydride. These etc. can be used individually or in combination of 2 or more types.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride. Cycloaliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure. Specific examples include: 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1 , 2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride and other cycloalkane tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7 -En-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and their positional isomers. These etc. can be used individually or in combination of 2 or more types. Specific examples of acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butane tetracarboxylic dianhydride and 1,2,3,4-pentane tetracarboxylic dianhydride These can be used alone or in combination of two or more kinds. In addition, cycloaliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride can be used in combination.

Among the above-mentioned tetracarboxylic dianhydrides, from the viewpoints of high impact resistance, high modulus of elasticity, high surface hardness, high transparency, high flexibility, high bending resistance, and low coloring properties of the optical film, it is preferable 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid Dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl tetracarboxylic dianhydride, 2,2-bis(3,4 -Dicarboxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof, more preferably 3,3',4,4'- Biphenyltetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof, and more preferably 4,4'-(hexafluoroisopropylidene Base) diphthalic dianhydride (6FDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA).

As the dicarboxylic acid compound used to produce the resin, terephthalic acid, isophthalic acid, 4,4'-oxybisbenzoic acid, or chloro compounds such as terephthalic acid, isophthalic acid, or the like can be preferably used. In addition to terephthalic acid, isophthalic acid, 4,4'-oxybisbenzoic acid or its chlorinated compounds, other dicarboxylic acid compounds can also be used. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and similar chlorinated compounds, acid anhydrides, and the like, and two or more of them can be used in combination. Specific examples include: isophthalic acid; naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; chain hydrocarbon dicarboxylic acid with carbon number 8 or less The compound and two benzoic acids are _{connected by a single bond, -CH 2} -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or phenylene compound, and the like Chlorine compounds. As a specific example, 4,4'-oxybis(benzoic acid chloride), terephthalic acid chloride or m-phthalic acid chloride is preferred, and 4,4'-oxybis( Benzoyl chloride) is used in combination with terephthaloyl chloride.

Furthermore, the above-mentioned polyamidoimide resin may also react with tetracarboxylic acid, tricarboxylic acid and their anhydrides and derivatives in addition to the above-mentioned tetracarboxylic acid compound within the range of not damaging the various physical properties of the optical film. Become.

Examples of the tetracarboxylic acid include water adducts of the anhydrides of the above-mentioned tetracarboxylic acid compounds.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related chlorinated compounds, acid anhydrides, and the like, and two or more of them may be used in combination. Specific examples include: 1,2,4-benzenetricarboxylic acid anhydride; 1,3,5-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; A compound in which phthalic anhydride and benzoic acid are linked by a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO _{2-or phenylene} .

When producing the resin, the usage amount of the diamine compound, the tetracarboxylic acid compound, and/or the dicarboxylic acid compound can be appropriately selected according to the desired ratio of each structural unit of the polyamide-based resin.

When the resin is produced, the reaction temperature of the diamine compound, the tetracarboxylic acid compound, and the dicarboxylic acid compound is not particularly limited, and is, for example, 5 to 350°C, preferably 20 to 200°C, and more preferably 25 to 100°C. The reaction time is also not particularly limited, and is, for example, about 30 minutes to 10 hours. The reaction can be carried out in an inert gas atmosphere or under reduced pressure as needed. In a preferred aspect, the reaction is carried out while stirring under normal pressure and/or an inert gas atmosphere. In addition, the reaction is preferably carried out in a solvent inert to the reaction. The solvent is not particularly limited as long as it does not affect the reaction. Examples include water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methyl Alcohol solvents such as oxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-pentane Lactone, propylene glycol methyl ether acetate, ethyl lactate and other ester solvents; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, methyl isobutyl ketone and other ketone solvents; Aliphatic hydrocarbon solvents such as pentane, hexane and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxyethane Ether solvents; chlorine-containing solvents such as chloroform and chlorobenzene; amine solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; Sulfur-containing solvents such as turpentine and cyclobutyl; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations thereof (mixed solvents), etc. Among them, from the viewpoint of solubility, an amide-based solvent can be preferably used.

In the imidation step during the production of the polyimidimide resin, the imidization can be carried out in the presence of an imidation catalyst. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, and N-butyl Alicyclic amines such as pyrrolidine, N-butylpiperidine, and N-propyl hexahydroazepine (monocyclic); azabicyclo[2.2.1]heptane, azabicyclo[3.2.1] Alicyclic amines (polycyclic) such as octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane; and pyridine, 2-picoline (2-picoline), 3-picoline, 4-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-lutidine, 2 ,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline and other aromatic amines. In addition, from the viewpoint of facilitating the promotion of the imidization reaction, it is preferable to use an acid anhydride together with the imidization catalyst. The acid anhydrides include conventional acid anhydrides used in the imidization reaction, and specific examples thereof include aliphatic anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic acid.

Polyamide resins can be isolated (separation and purification) by conventional methods, such as separation methods such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination of these methods. In a preferred aspect, isolation can be performed by adding a large amount of alcohol such as methanol to the reaction solution containing the transparent polyamide resin to precipitate the resin, and then performing concentration, filtration, drying, etc. for isolation.

In one embodiment of the present invention, in addition to the polyamide-based resin, the optical film may include at least one type of filler. Examples of the filler include organic particles and inorganic particles, and preferably inorganic particles. Examples of inorganic particles include metal oxide particles such as silicon oxide, zirconium oxide, aluminum oxide, titanium oxide, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide, Metal fluoride particles such as magnesium fluoride and sodium fluoride. Among them, from the viewpoint of easily improving the elastic modulus and/or tearing strength of the optical film and improving the impact resistance, preferably silicon oxide particles, Zirconia particles and alumina particles, more preferably silica particles. These fillers can be used alone or in combination of two or more kinds.

The average primary particle size of the filler, preferably silica particles, is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, particularly preferably 20 nm or more, more preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less, still more preferably 70 nm or less, particularly preferably 60 nm or less, especially more preferably 50 nm or less, and particularly preferably 40 nm the following. If the average primary particle size of the silicon oxide particles is within the above range, it is easy to inhibit the aggregation of the silicon oxide particles and improve the optical properties of the optical film. The average primary particle size of the filler can be measured by the BET (Brunauer-Emmett-Teller, Buert) method. Furthermore, the average primary particle size can be measured by image analysis of a transmission electron microscope or a scanning electron microscope.

In one embodiment of the present invention, when the optical film contains a filler, preferably silica particles, the content of the filler relative to 100 parts by mass of the optical film is usually 0.1 part by mass or more, preferably 1 part by mass or more, It is more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 60 parts by mass or less. If the content of the filler is more than the above lower limit, it is easy to increase the elastic modulus of the optical film. Moreover, if the content of the filler is below the above upper limit, it is easy to improve the optical properties of the optical film. In addition, when the optical film contains fillers such as silica particles, it is easy to increase the elastic modulus, but there is a possibility that the flexibility may decrease due to the increase in the mechanical strength. The optical film of the present invention has a layer with excellent flexibility inside, so even when the optical film contains a filler, it can have high flexibility.

In one embodiment of the present invention, the optical film may further contain an ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those generally used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may include a compound that absorbs light with a wavelength of less than 400 nm. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone compounds, salicylate compounds, benzotriazole compounds, and triazole compounds. The ultraviolet absorber can be used alone or in combination of two or more kinds. By containing the ultraviolet absorber in the optical film, the deterioration of the resin is suppressed, and therefore the visibility can be improved when the optical film is applied to an image display device or the like. In this specification, "system compound" refers to a derivative of a compound with the expression "system compound" attached. For example, "benzophenone-based compound" refers to a compound having benzophenone as a parent skeleton and a substituent bonded to benzophenone.

When the optical film contains an ultraviolet absorber, the content of the ultraviolet absorber relative to 100 parts by mass of the optical film is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more, more preferably It is 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 6 parts by mass or less. The preferred content varies according to the UV absorber used, but if the content of the UV absorber is adjusted in such a way that the light transmittance of 400 nm is about 20-60%, the light resistance of the optical film can be improved and it is easy to Improve transparency.

In one embodiment of the present invention, the optical film may further contain other additives in addition to fillers and ultraviolet absorbers. Examples of other additives include antioxidants, mold release agents, stabilizers, bluing agents, flame retardants, pH adjusters, silica dispersants, slip agents, thickeners, and leveling agents. When other additives are contained, the content thereof may be preferably 0.001 to 20 parts by mass relative to 100 parts by mass of the optical film, more preferably 0.01 to 15 parts by mass, and still more preferably 0.1 to 10 parts by mass.

(Method of manufacturing optical film) The manufacturing method of the optical film of the present invention is not particularly limited, and the manufacturing method may at least include, for example, the following steps: (a) A step of preparing a resin composition (hereinafter, also referred to as "varnish") containing at least a polyamide-based resin and a solvent (varnish preparation step); (b) The step of applying varnish to the support material to form a coating film (coating step); and (c) The step of drying the above-mentioned coating film to form an optical film (optical film forming step).

In the varnish preparation step, the varnish is prepared by dissolving the polyamide resin in a solvent, adding additives such as the filler and ultraviolet absorber as necessary, and stirring and mixing the varnish. Furthermore, when silica particles are used as a filler, the dispersion of silica sol containing silica particles can be replaced with a solvent that can dissolve the above-mentioned resin, such as the following solvents used to prepare varnishes, to obtain silicon The sol is added to the resin.

The solvent used to prepare the varnish is not particularly limited as long as it can dissolve the above-mentioned resin. From the viewpoint of easy production of the optical film of the present invention having the above-mentioned characteristics, as the solvent, for example, N,N-dimethyl is preferably used. Amine-based solvents such as acetamide (DMAc) and N,N-dimethylformamide (DMF); lactone-based solvents such as γ-butyrolactone (GBL) and γ-valerolactone; dimethyl sulfide Sulfur-containing solvents such as dimethyl sulfide and cyclobutane; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations thereof, preferably selected from amide-based solvents and lactones A solvent in the group of solvents. These solvents can be used alone or in combination of two or more. In addition, the varnish may contain water, alcohol-based solvents, ketone-based solvents, acyclic ester-based solvents, ether-based solvents, and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass, and still more preferably 5 to 15% by mass.

In the coating step, a varnish is applied to the support by a known coating method to form a coating film. As well-known coating methods, for example, roll coating methods such as wire bar coating, reverse coating, and gravure coating, die nozzle coating method, carma coating method, and die lip coating method can be cited. Method, spin coating method, screen coating method, spray coating method, dipping method, spray method, casting method, etc.

In the film formation step, an optical film can be formed by drying the coating film and peeling it from the support material. A step of drying the optical film after peeling can also be provided. The drying of the coating film can usually be carried out at a temperature of 50 to 350°C. The coating film can be dried in an inert gas atmosphere or under reduced pressure as needed.

Examples of supporting materials include SUS (Steel Use Stainless) plates for metal systems, PET films, PEN (polyethylene naphthalate, polyethylene naphthalate) films, other polyamide resin films, and resin systems. Polyimide-based resin films, cycloolefin-based polymer (COP) films, acrylic films, etc., or these resin films with hard coat layers, glass substrates, etc. Among them, from the viewpoint that it is easy to _{adjust the I 1} /I ₂ and/or I ₃ /I ₂ of the optical film to the above-mentioned range, and the viewpoint that the smoothness and heat resistance of the optical film are excellent, the support material is preferably PET film, COP film, resin film with hard coat layer, SUS plate, glass substrate, etc., furthermore, it is easy to _{adjust I 1} /I ₂ and/or I ₃ /I ₂ to the above-mentioned range of viewpoint, cost, and production From the viewpoint of performance, the support material is more preferably a SUS plate or a resin film with a hard coat layer, and more preferably a SUS plate or a PET film with a hard coat layer.

From the viewpoint of ease of _{adjusting the above-mentioned I 1} /I ₂ and/or I ₃ /I ₂ to the above-mentioned range, it is preferable to perform the drying of the coating film in the above-mentioned film formation step by the following manufacturing method: It includes the following steps: after the coating film is dried to a specific solvent amount, the support material (base material) is peeled off to obtain a raw film; and the raw film is heated in a tenter furnace divided into a plurality of spaces. step. Furthermore, in the tenter furnace, it is preferable to perform the heating step by hot air treatment in at least one space, and to perform the heating step by radiation treatment in at least one space. Furthermore, the tenter furnace refers to a furnace that fixes both ends in the width direction of the film and heats it. Furthermore, in this specification, the heating device for heating the raw film including the tenter oven is also called an oven.

With reference to the drawings, the manufacturing method of the optical film of this embodiment will be described. FIG. 1 is a schematic cross-sectional view of a preferred embodiment of a method of manufacturing an optical film in an embodiment of the present invention. In FIG. 1, a raw film 20 containing at least a polyamide-based resin is carried into the tenter furnace 100, is heated in a heating zone in the tenter furnace 100, and then is carried out from the tenter furnace 100. In this specification, the film that has undergone the heating step and the amount of solvent changes over time but is in the heating step or transported in the oven is called the raw film, and the film that has undergone the heating step and carried out from the oven is called the optical film .

The raw film 20 may be unrolled from the roll on which the raw film is wound and carried into the tenter furnace 100, or it may be continuously carried into the tenter furnace from the immediately preceding step. 2 is a step cross-sectional view schematically showing a preferred embodiment of the heating step in the method of manufacturing the optical film of the present invention. As shown in Figure 2, the raw film 20 is preferably in a direction perpendicular to the transport direction of the film (also referred to as MD direction (Machine direction) and length direction) (also referred to as TD direction (Transverse Direction) ), the film on the width direction) is transported in the tenter furnace while the two ends of the film are fixed. The fixing is performed, for example, with the holding device 18.

Needle plates, clamps, film chucks and other holding devices commonly used in film manufacturing devices can be used to fix both ends. Both ends of the fixation can be adjusted appropriately according to the holding device used, preferably at a distance of less than 50 cm from the end of the film. As shown in FIG. 2, the raw film can be transported while being held at both ends by a plurality of holding devices 18. Regarding the plurality of holding devices 18 arranged at one end of the film, the distance between the adjacent holding devices is preferably such that it can suppress defects such as cracking caused by the shaking of the film or the dimensional change caused by heating. The distance between adjacent holding devices 18 is preferably 1-50 mm, more preferably 3-25 mm, and still more preferably 5-10 mm. In addition, the holding device is preferably arranged in the following manner: when the straight line orthogonal to the film conveying axis is aligned with the center of the holding portion of any holding device at one end of the film, the intersection of the straight line and the other end of the film is closest to the intersection The distance between the center of the holding part of the holding device is preferably 3 mm or less, more preferably 2 mm or less, and still more preferably 1 mm or less. Thereby, the difference in the stress between the opposite ends of the film can be reduced, and therefore, the deviation of the optical properties in the obtained optical film can be suppressed. In addition, by drying the film while fixing the film with a holding device under such conditions, shaking during film drying is suppressed, and it is easy to manufacture the optical film of the present invention that satisfies the above-mentioned formula.

As an example of the operation of fixing both ends of the film with the holding device, the following method can be cited: before loading into the tenter furnace or after loading into the tenter furnace, at an appropriate time, use a plurality of films opposed to each other in the width direction of the film The chuck fixes the two ends of the film in the width direction. By these operations, the shaking of the film is suppressed, and it is possible to obtain an optical film in which defects such as thickness unevenness and damage are sufficiently suppressed. In addition, it is easy to manufacture the optical film of the present invention that satisfies the above formula. The fixing of both ends of the film only needs to be released in a timely manner after the heating step. It can be carried out in the tenter furnace or after being removed from the tenter furnace.

The overall length of the film conveying direction of the tenter furnace used in the heating step is usually 10-100 m, preferably 15-80 m, more preferably 15-60 m. The inside of the stenter furnace may be one space or divided into a plurality of spaces. However, in the embodiment of the present invention, the stenter furnace that performs the heating step adopts the one in which the inside is divided into a plurality of spaces. The above-mentioned space may be a controllable space such as temperature conditions or wind speed conditions, or may not have physical boundaries such as partition plates. When the inside of the tenter furnace is divided into a plurality of spaces, it can be divided into a plurality of spaces perpendicular or parallel to the transport direction of the film. The number of spaces is usually 2-20, preferably 3-18, more preferably 4-15, and still more preferably 5-10. Regardless of the internal structure of the stenter furnace, the entire stenter furnace can be used as a heating zone, or a part of the interior can be used as a heating zone. Referring to FIG. 1, all three areas of areas 10, 12, and 14 may be heating areas, or one of the areas, for example, area 14 may be a heating area.

Multiple stenter furnaces can also be used. The number of tenter furnaces in this case is not particularly limited, and it can be set to 2-12, for example. The inside of each stenter furnace can be the structure described above. A plurality of tenter furnaces can be continuously installed so as to transport the film without contacting the outside atmosphere. In the case of using a plurality of tenter furnaces, all tenter furnaces can be used as heating zones, or part of the tenter furnaces can be used as heating zones. In addition to the tenter oven, an oven can also be used as other equipment. In this specification, the oven means a machine that can heat the film, including a heating furnace and a drying furnace. The heating furnace can adopt either hot air treatment or radiation treatment, or a heating furnace that uses them in combination. When an oven is used in combination, the internal structure of the oven, the quantity used, and the heating conditions can be adjusted appropriately within the range that the optical film of the present invention can be obtained, and it is preferably the same as the tenter oven described in this specification. the same.

In the case where the inside of the tenter furnace is divided into a plurality of spaces, the circulation and exhaust of the air inside the tenter furnace are preferably performed in each space. When there are multiple tenter furnaces, it is preferable to perform the air circulation and exhaust in each space. Carried out in a stenter furnace. The temperature inside the tenter furnace is preferably adjustable for each tenter furnace. When the inside of the tenter furnace is divided into a plurality of spaces, it is preferable that the temperature can be adjusted independently in each space. The temperature setting of each space can be the same or different. However, the temperature of each tenter furnace or space preferably satisfies the following temperature range.

The tenter furnace 100 performing the heating step performs the heating step by hot air treatment in at least one space, and performs the heating step by radiation treatment in at least one space. The heating step is preferably performed in a hot air treatment mode in all the spaces where the step is performed. The heating step of the radiation treatment method can be performed in another space different from the hot air treatment method, but it is preferable to perform the heating step in combination with the hot air treatment method.

The heating step of the hot air treatment method can be performed by installing a nozzle for blowing hot air in the tenter furnace. The heating step of the radiation treatment method can be performed by installing an IR heater or the like in a tenter furnace and irradiating radiation onto the film.

Hereinafter, as an example of the embodiment of the present invention, the hot air treatment method using nozzles and the radiation treatment method using IR heaters will be sequentially described starting from the hot air treatment method using nozzles.

1, the tenter furnace 100 performing the heating step is provided with a plurality of upper nozzles 30 on its inner upper surface 100a, and a plurality of lower nozzles 32 on its inner lower surface 100b. The upper nozzle 30 and the lower nozzle 32 are opposed to each other in the vertical direction. For example, the nozzles can be provided with 4 pairs of nozzles (a total of 8) as in the area 14 of FIG. 1, or 10 pairs of nozzles (a total of 20) can be provided as in the area 12 of FIG. From the viewpoint of simplifying the structure of the tenter furnace and uniformly heating the raw film, and the viewpoint of easily _{adjusting the I 1} /I ₂ and/or I ₃ /I _{2 of the} optical film to the above range, the adjacent nozzles The interval is preferably 0.1 to 1 m, more preferably 0.1 to 0.5 m, and still more preferably 0.1 to 0.3 m.

When the inside of the tenter furnace is divided into a plurality of sections, the number of hot air blowing nozzles installed in each space can usually be set to 5-30. From the viewpoint of easy production of the optical film of the present invention that satisfies the above formula and easy improvement of the optical uniformity of the optical film, the number of nozzles is preferably 8-20. If the number of nozzles is within the above range, the curvature of the floating film is not likely to become too large, and the film tends to float between the nozzles, that is, it is easy to float.

The nozzle 30 provided on the upper side of the upper surface 100a of the tenter furnace 100 has a blowing port in the lower part, and can blow hot air in the downward direction (arrow B direction). On the other hand, the nozzles 32 respectively provided on the lower surface of the lower surface of the tenter furnace 100 have blowing outlets on the upper part, and can blow hot air in the upward direction (the arrow C direction). Furthermore, although not shown in FIG. 1, the upper nozzle 30 and the lower nozzle 32 have a depth of a specific size in a direction perpendicular to the paper surface of FIG. 1, so that the raw film can be uniformly heated in the width direction.

In the manufacturing method of the optical film of this embodiment, the blowing speed of the hot air from the blowing outlets of all the upper nozzles 30 and all the lower nozzles 32 provided in the heating zone is preferably 2-25 m/sec. From the viewpoint of easy production of the optical film of the present invention that satisfies the above formula and easy improvement of the optical uniformity of the optical film, the blowing wind speed is more preferably 2 to 23 m/sec, and more preferably 8 to 20 m/sec . Also, from the same point of view, the air volume blown from each nozzle 30 or 32 is preferably 0.1 to 3 m ³ /sec per 1 m of the length of the nozzle in the width direction of the raw material film, and more preferably 0.1 to 2.5 m ³ /sec, more preferably 0.2 to 2 m ³ /sec.

If the wind speed and air volume blown from the nozzle are within the above range, the heating of the raw film can be performed uniformly. Therefore, it is often easy to obtain a film with uniform optical and physical properties on the entire surface of the film, and it is easy to manufacture the present invention satisfying the above formula Optical film is therefore preferred. Specifically, if the heating step is performed under the above conditions, the deviation of the in-plane retardation value in the film width direction becomes smaller, and it is easy to obtain an optical film having a more uniform in-plane retardation value on the entire film surface. Therefore, when applied to a display device, the variation in contrast is suppressed, and it becomes a front panel with excellent visibility. In addition, if the heating step is performed under the above conditions, it is easy to manufacture the optical film of the present invention that satisfies the above formula and is heated uniformly. Therefore, the deviation of the amount of solvent remaining in the film becomes small, and it is easy to obtain elasticity on the entire surface of the film. Optical film with more uniform modulus. Therefore, the flexibility of the entire film surface is not easily deviated, and the occurrence of damage caused by the difference in the flexibility of the film surface can be suppressed.

In the tenter furnace, the raw film 20 is heated from room temperature to the temperature at which the solvent contained in the raw film evaporates, but the raw film 20 is held by the holding device 18 so that the length in the width direction of the raw film hardly changes. Therefore, it is easy to cause sagging due to thermal expansion. If the blowing air speed and the blowing air volume are within the above-mentioned ranges, the raw film 20 can be sufficiently heated, and the raw film 20 can be suppressed from sagging or shaking.

The blowing speed of the hot air can be measured at the hot air blowing outlets of the nozzles 30 and 32 using a commercially available thermal anemometer. In addition, the amount of air blown from the blow-out port can be obtained from the product of the blow-out wind speed and the area of the blow-out port. Furthermore, from the viewpoint of measurement accuracy, it is preferable that the blowing speed of the hot air be measured at about 10 locations at the blowing ports of each nozzle and set as the average value.

The blowing speed and the blowing air volume of the hot air can be appropriately adjusted according to the physical properties (optical properties, mechanical properties, etc.) of the optical film to be manufactured, but in any form, it is preferably within the above-mentioned range. Thereby, it is possible to obtain an optical film having a more sufficiently uniform phase difference and a sufficiently high axial accuracy. Regarding the heating zone, it is more preferable that the blowing air velocity in all heating zones is 25 m/sec or less and the blowing air volume is 2 m ³ /sec or less.

In this embodiment, when the raw material film 20 is not introduced into the tenter furnace 100, the wind speed of the hot air at the position of the raw material film 20 is preferably 5 m/sec or less, and more preferably at least less than heating This wind speed is in the area. By using such hot air to heat the raw film 20, it is easy to obtain the optical film of the present invention that satisfies the above formula, and an optical film with sufficiently excellent optical uniformity can be obtained.

In the heating zone, the difference between the maximum value and the minimum value in the width direction (the direction perpendicular to the paper surface of FIG. 1) of the hot air blowing from the blowing outlets of each nozzle 30 and 32 is preferably 4 m/sec or less. By using such hot air with less deviation in the wind speed in the width direction, it is easy to manufacture the optical film of the present invention that satisfies the above formula, and an optical film with higher optical uniformity in the width direction can be obtained. In addition, by using hot air with less deviation in wind speed like this, it is easy to manufacture the optical film of the present invention that satisfies the above formula, and an optical film with higher optical uniformity can be obtained.

In this embodiment, the wind speed of the hot air blowing on the film is preferably higher than the wind speed of other conveying paths in the oven just after being moved into the oven. In the case where the inside of the oven is not divided into multiple pieces, just after being moved into the oven (hereinafter referred to as conveying path 1) means that the distance from the inlet of the oven is less than the length of the oven (the length from the inlet of the oven to the outlet) 1/10 of the distance. When the inside of the oven is divided into a plurality of spaces, the conveying path 1 refers to the space through which the film first passes. In the case of using multiple ovens, you can set the same as described above according to the internal structure of the oven used first, or set the wind speed of the first oven to be greater than the wind speed in the second and subsequent ovens .

In the case where the inside of the oven is not divided into plural pieces, the other conveying path refers to the conveying path part that is more than 1/10 of the oven length from the oven inlet. When the inside of the oven is divided into multiple spaces, it refers to any space after the second space through which the film passes. In the case of using multiple ovens, you can set the same as described above according to the internal structure of the oven used first, or set the wind speed in any oven in the second and subsequent ovens to be less than the one that passed the first The wind speed of the oven.

The difference between the wind speed of the conveying path 1 and the wind speed of other conveying paths in the oven is preferably in the range of 0.1-15 m/sec. The above-mentioned difference in wind speed is more preferably 0.2 m/sec or more, still more preferably 12 m/sec or less, still more preferably 8 m/sec or less, still more preferably 5 m/sec or less, and particularly preferably 3 m/sec. Less than seconds. If the wind speed just after being moved into the oven is greater than the wind speed of other conveying paths in the oven in such a way that the difference in wind speed falls within the above range, the solvent in the film can often be removed more efficiently. If the difference in wind speed is too large, the film may shake due to the difference in wind speed, and it may not be easy to manufacture the optical film of the present invention that satisfies the above formula. In addition, it may cause deviations in optical properties such as surface shape defects or retardation of the obtained optical film.

Regarding the difference between the wind speed of the conveying path 1 and the wind speeds of other conveying paths in the oven, the difference between the hot air speed blowing from the nozzles installed on the conveying path 1 and the hot air blowing speeds from the nozzles installed on other conveying paths Find out. When there is a difference of 2 m/sec or more between the speed of the hot air blown to the film and the speed of the hot air blown from the nozzle, the difference between the speed of the hot air near the film on the conveying path 1 and the other conveying paths can also be calculated as the difference Out.

The other conveying path is preferably a conveying path located below the conveying path 1 (referred to as a conveying path 2). In the case where the inside of the oven is not divided into a plurality of pieces, the conveying path 2 refers to the conveying path at a position that is 2/10 of the oven length from the entrance of the oven. When the inside of the oven is divided into a plurality of spaces, the conveying path 2 refers to the second space through which the film passes. In the case of using multiple ovens, you can set the same as described above according to the internal structure of the oven used first, or set the wind speed of the second oven to be lower than the oven that passed the first.

When the difference between the wind speeds of the conveying path 1 and the conveying path 2 is set as described above, the wind speeds of the conveying paths after the conveying path 2 need only be within the range of the above-mentioned hot air blowing wind speed. The difference between the wind speed of the conveying path after conveying path 2 and the wind speed of conveying path 1 or conveying path 2 is preferably 0.1-12 m/sec, more preferably 0.2-8 m/sec. If the difference in wind speed is within this range, it is often possible to suppress the shaking of the film caused by the difference in wind speed, and it is easy to manufacture the optical film of the present invention that satisfies the above formula, and it is easy to adjust the weight loss rate of the obtained optical film to The desired range.

When the inside of the oven is not divided into multiple spaces, the above-mentioned difference in wind speed can be adjusted only by adjusting the nozzle setting position, the nozzle's hot air blowing speed and air volume, and the air flow direction in the oven. When the inside of the oven is divided into multiple spaces, just adjust the nozzle setting position, the nozzle hot air blowing speed and air volume, the air flow direction in the oven, etc. in the first space and subsequent spaces. . In the case of using multiple ovens, it can be done in the same way as described above according to the structure of the first oven, as long as the nozzle setting position and the nozzle are set in a way that the wind speed in the first oven and the second and subsequent ovens are different The hot air blowing speed and air volume, the airflow in the oven, etc. are sufficient.

In the heating zone in the tenter furnace 100, the distance L (the shortest distance) between the upper nozzle 30 and the lower nozzle 32 facing each other is preferably 150 mm or more, more preferably 150 to 600 mm, and still more preferably 150 ～400 mm. By arranging the upper nozzle and the lower nozzle at such an interval L, the shaking of the film in each step can be suppressed more reliably, and the optical film of the present invention that satisfies the above formula can be easily manufactured.

In addition, the difference between the highest temperature and the lowest temperature (ΔT) in the width direction (the direction perpendicular to the paper surface of Fig. 1) of the hot air in the blowing outlets of the respective nozzles 30 and 32 of the heating zone is preferably 2°C. Below, it is more preferable that all are 1°C or less. By using hot air with a sufficiently small temperature difference in the width direction to heat the film, the deviation of the orientation in the width direction can be further suppressed. Furthermore, the temperature of the hot air is preferably 150 to 400°C, more preferably 150 to 300°C, and still more preferably 150 to 250°C.

As the nozzle that can be used in the manufacturing method of the optical film, the nozzle generally used in the film manufacturing device can be used. As an example, a jet nozzle (also called a slit nozzle) can be used, which has an extension in the width direction of the raw film A nozzle with a slit-shaped blow-out port; and a perforated nozzle (also called a porous nozzle), which is a nozzle with a plurality of blow-out ports arranged in the raw film conveying direction and the raw film width direction, respectively.

The nozzle has a structure that is provided on the upper surface 100a of the tenter oven 100 and blows hot air downward to the film, and a structure that is provided on the lower surface 100b of the tenter furnace 100 and blows hot air upward to the film.

The jet nozzle has a slit extending in the width direction of the film as a blowing port for hot air. The slit width of the slit is preferably 5 mm or more, more preferably 5-20 mm. By setting the slit width to 5 mm or more, the optical uniformity of the obtained optical film can be further improved. Furthermore, the area of the blowing port of each jet nozzle can be obtained from the product of the length of the jet nozzle in the width direction of the nozzle and the slit width. The product of the area of the blowing outlet of each nozzle and the blowing wind speed is the amount of hot air blowing from each nozzle. By dividing the hot air blowing volume by the length of the slit along the film width direction, the hot air blowing air volume per 1 m of the length of the nozzle in the film width direction can be obtained.

Regarding the perforated nozzle, the cross section perpendicular to the longitudinal direction may have a rectangular shape, or may have a trapezoidal shape that gradually expands toward the surface facing the raw film 20. The perforated nozzle has a plurality of openings (for example, circular openings) on the surface opposite to the film, that is, the surface on the lower side. The blowing outlet of the hot air of the perforated nozzle includes a plurality of openings arranged on the blowing surface. The plurality of openings are outlets for hot air, and the hot air is blown out from the openings at a specific wind speed. A plurality of openings are arranged in the length direction of the film, and a plurality of openings are also arranged in the width direction. The openings may be arranged in a staggered manner, for example.

The area of the blow-out port of each perforated nozzle can be calculated based on the sum of the area of all the openings provided in a perforated nozzle. The product of the area of the blowing outlet of each nozzle and the blowing wind speed is the amount of hot air blowing from each nozzle. By dividing the hot air blowing volume by the length of the slit along the film width direction, the hot air blowing air volume per 1 m of the length of the nozzle in the film width direction can be obtained.

In the case of using a perforated nozzle, the difference between the maximum blowing speed and the minimum blowing speed in the width direction of the hot air in the nozzle outlet can be used as the maximum blowing speed and minimum blowing speed of the hot air blowing from multiple openings on the same nozzle Calculate the difference in blowing speed. The difference between the highest temperature and the lowest temperature in the width direction of the hot air in the nozzle outlet can also be obtained in the same way.

If all the nozzles installed in the tenter furnace 100 are perforated nozzles, the total area of the hot air outlets in the entire tenter furnace 100 can be increased. Therefore, the wind pressure of the hot air blowing on the film can be reduced, and the shaking of the film can be further reduced. Thereby, it is easy to manufacture the optical film of the present invention that satisfies the above formula, and the optical uniformity of the obtained optical film can be further improved. In the tenter furnace or in the heating zone, the raw film 20 is heated from room temperature to the temperature at which the solvent contained in the raw film evaporates, but the length of the raw film in the width direction is hardly changed by the holding device 18 The raw film 20 tends to sag due to thermal expansion. By using perforated nozzles in the heating zone, sagging or shaking of the raw film 20 can be further suppressed, and the optical film of the present invention satisfying the above formula can be easily manufactured.

The size and quantity of each opening on the surface of the perforated nozzle can be adjusted appropriately within the following range: the blowing speed of the hot air in each opening is 2-25 m/sec, and the length of the nozzle along the film width is 1 The air volume blowing from each nozzle in m is 0.1～3 m ³ /sec.

From the viewpoint of making the wind speed blown from each opening of the perforated nozzle more uniform, the shape of the opening is preferably circular. In this case, the diameter of the opening is preferably 2-10 mm, more preferably 3-8 mm.

When using perforated nozzles, the length of the film conveying direction on the surface of each nozzle is preferably 50-300 mm. Furthermore, the distance between the adjacent perforated nozzles is preferably 0.3 m or less. In addition, the ratio of the total area of the openings of the perforated nozzle (the area of the blowing outlet) to the length of the perforated nozzle in the film width direction (the total area of the perforated nozzle openings (m ² )/the film width of the perforated nozzle The length (m)) is preferably 0.008 m or more.

By using this perforated nozzle, the area of the hot air outlet can be enlarged. Thereby, the wind speed of the hot air can be sufficiently reduced, and the hot air can be blown out with a sufficient air volume, so that the film can be heated more uniformly. As a result, it is easy to manufacture the optical film of the present invention that satisfies the above formula, and it is easy to manufacture a film with more uniform retardation and higher axis accuracy.

Similar to the nozzles, the tenter furnace 100 that performs the heating step can be provided with IR heaters on its inner upper surface 100a or its inner lower surface 100b, which are arranged opposite to each other in the up and down direction. In addition, multiple IR heaters can be installed. As the IR heater, any IR heater generally used in film manufacturing equipment may be used.

The radiation irradiated to the film is preferably a heat ray with a wavelength of 3 to 7 μm. In addition, in the radiation treatment method, if the temperature of the space where the heating step is performed is within the above-mentioned temperature range, the raw film can also be irradiated with radiation whose temperature is higher than the space temperature by more than 30°C.

In the embodiment of the present invention, it is preferable to use the above-mentioned nozzle (hot air treatment method) and IR heater (radiation treatment method) in combination in the tenter furnace 100 where the heating step is performed. In this case, as long as the IR heater is installed between the adjacent nozzles or between the nozzles and the inner wall of the tenter furnace (including the wall of the partition space).

In this case, as long as the temperature of the space where the heating step is performed is within the above temperature range, in the radiation treatment method, radiation with a temperature higher than the temperature of the space can be irradiated onto the film. The temperature of the radiation can be, for example, a temperature higher than the temperature of the space by 30°C or more, or a temperature higher than the temperature of the space by 150°C or more. Here, the temperature of the radiant rays refers to the temperature set by a machine that emits radiant heat like the set temperature of an IR heater. The difference between the temperature of the radiation and the temperature of the radiation irradiated on the film is preferably 5°C or less, more preferably 3°C or less, and still more preferably 1°C or less.

If the nozzle (hot air treatment method) and IR heater (radiation treatment method) are used together in the tenter furnace 100, although the temperature of the heating zone or the temperature in the tenter furnace (temperature of the gas atmosphere) is irradiated to On the raw material film, the heating step can be performed while suppressing the temperature in the heating zone or the tenter furnace from being too high. Thereby, compared with the case where only any one of the treatment methods is used for the heating step, the yellowness (YI) of the obtained optical film can be kept at a small value, and the weight loss rate can be adjusted to a specific range more quickly. In addition, by irradiating the raw film with radiation at a temperature higher than the temperature in the heating zone or the stenter furnace, the resin in the raw film is easily aligned or re-aligned. Therefore, the in-plane retardation value of the obtained optical film is often The deviation will become smaller at the center and both ends of the membrane. Therefore, as described above, the obtained optical film has more excellent image visibility when applied to a display device.

The heating step using the hot air treatment method and the radiation treatment method together is preferably performed between the space where the raw material film first passes through the plurality of spaces in the stenter furnace where the heating step is performed to the space approximately in the middle of the full length of the stenter furnace. Thereby, not only the time required for the heating step can be shortened, but also an optical film with more excellent in-plane phase difference uniformity can be manufactured.

The heating step is preferably performed in the range of 150 to 350°C. In the embodiment of the present invention, if the heating step is within this temperature range, the raw film may be easily adjusted to the following weight loss rate M. In addition, it is often easy to _{adjust I 1} /I ₂ and/or I ₃ /I ₂ to the above-mentioned range. The temperature range is more preferably 170°C or higher, still more preferably 180°C or higher, more preferably 300°C or lower, still more preferably 250°C or lower, and particularly preferably 230°C or lower. If the temperature of the heating step is within the above-mentioned range, it is easy to adjust the yellowness of the obtained optical film into the above-mentioned preferred range. In addition, the temperature of the space in which the heating step is performed is more preferably 170°C or higher, and still more preferably 180°C or higher. Regarding the temperature in the tenter furnace for the heating step, as long as the heating zone is within the above range. When there are a plurality of tenter furnaces and the inside of the tenter furnace is divided into a plurality of spaces, adjustments can be made appropriately, but it is preferable that all the tenter furnaces or spaces are within the above-mentioned range.

The moving speed of the raw film 20 in the tenter furnace 100 can usually be adjusted appropriately within the range of 0.1-50 m/min. The upper limit of the above-mentioned moving speed is preferably 20 m/min, more preferably 15 m/min. The lower limit of the above-mentioned moving speed is preferably 0.2 m/min, more preferably 0.5 m/min, still more preferably 0.7 m/min, and particularly preferably 0.8 m/min. If the moving speed is fast, in order to ensure the desired drying time, the length of the tenter furnace will often be lengthened and the equipment will be larger. In the embodiment of the present invention, if the moving speed of the raw film 20 in the tenter furnace 100 is within the above-mentioned range, it is often easy to adjust the raw film to the following weight loss rate M. In addition, the shaking of the film is often suppressed, it is easy to _{adjust I 1} /I ₂ and/or I ₃ /I ₂ to the above-mentioned range, and it is possible to suppress the occurrence of damage on the film surface.

The treatment time of the heating step is usually 60 seconds to 2 hours, preferably 10 minutes to 1 hour. The processing time can be adjusted appropriately considering the temperature, moving speed, hot air speed and air volume of the above-mentioned tenter furnace.

In one embodiment of the present invention, the manufacturing method of the optical film can perform the operation of changing the film width or the operation of keeping the film width while conveying in the heating step. As an example of the operation of changing the film width, an operation of extending the film in the width direction can be cited. The stretching ratio is preferably 0.7 to 1.3 times, more preferably 0.8 to 1.2 times, and still more preferably 0.8 to 1.1 times. As an example of the operation of keeping the film wide and conveying, there is an operation of holding so that the length in the width direction of the film hardly changes. The optical film obtained by these operations can be set to a length of about 0.7 to 1.3 times the length of the raw film in the width direction, and can be formed by extending, equalizing or shrinking the length of the raw film in the width direction. length. The stretching ratio is calculated as the ratio of the film width after stretching (except for the fixed part) to the film width except for the fixed part. Furthermore, in FIG. 2, the solid line indicates the case where the stretching magnification exceeds 1 time in the operation of stretching in the film width direction, and the dotted line indicates the case where the stretching magnification is equal or less than 1 time.

After the optical film in the heating step is carried out from the tenter furnace, it can be continuously supplied to the next step, or it can be rolled up and supplied to the next step. When the optical film is wound on a roll, other films such as a surface protective film and other optical films can be laminated and wound up. As the surface protection film laminated on the optical film, the same thing as the surface protection film laminated on the following raw material film can be used. The thickness of the surface protection film laminated on the optical film is usually 10-100 μm, preferably 10-80 μm.

＜Raw film＞ The raw material film supplied to the heating step contains at least a polyamide-based resin. The raw material film preferably contains the same components as those contained in the varnish used to form the raw material film described below, but it may be different due to structural changes of the components or evaporation of a part of the solvent. The raw material film may be a self-supporting film, and it may be a gel film.

From _{the viewpoint of easy adjustment of I 1} /I ₂ and/or I ₃ /I ₂ to the above-mentioned range, it is preferable to measure by thermogravimetry-differential calorimetry regardless of whether the raw material film contains an inorganic material (hereinafter, sometimes It is called "TG-DTA measurement") The calculated weight loss rate M from 120°C to 250°C is preferably about 1 to 40%, more preferably 3 to 20%, and even more preferably 5 to 15%. It is 5-12% to remove a part of the solvent from the above varnish. The weight loss rate M of the raw film can be measured by the following method using a commercially available TG-DTA measuring device. As the TG-DTA measuring device, TG/DTA6300 manufactured by Hitachi High-Tech Science can be used.

First, take a sample of about 20 mg from the raw material film, heat the sample from room temperature to 120°C at a temperature rise rate of 10°C/min, hold it at 120°C for 5 minutes, and then heat it up to 400 at a temperature rise rate of 10°C/min ℃, while heating under this condition, the weight change of the sample is measured. Next, it is sufficient to calculate the weight loss rate M (%) from 120°C to 250°C from the following formula based on the result of the TG-DTA measurement. In the following formula, W ₀ represents the weight of the sample after being kept at 120°C for 5 minutes, and W ₁ represents the weight of the sample at 250°C. M(%)=100－(W ₁ /W ₀ )×100

If the weight loss rate M of the raw material film is relatively large, when the raw material film is wound into a laminate with a substrate or a surface protection film, the deformation of the laminate is often suppressed, and the rollability of the laminate improve. In addition, it is easy to _{adjust I 1} /I ₂ and/or I ₃ /I ₂ within the above-mentioned range.

If the weight loss rate M of the raw material film is small to a certain extent, when the raw material film is wound into a laminate with the substrate or the surface protection film, the raw material film is often difficult to adhere to the substrate or the surface protection film. Therefore, the laminate can be easily rolled out of the roll while maintaining the uniform transparency of the raw material film. In addition, it is easy to _{adjust I 1} /I ₂ and/or I ₃ /I ₂ within the above-mentioned range.

The raw material film can be formed by drying the above-mentioned coating film and peeling it from the base material. The drying of the coating film can usually be carried out at a temperature of 50 to 350°C. The coating film can be dried in an inert gas atmosphere or under reduced pressure as needed. The raw material film obtained in the above-mentioned manner can be supplied to the above-mentioned heating step, thereby manufacturing the optical film of the present invention. The raw material film may be continuously conveyed and supplied to the heating step, or may be temporarily wound up and then supplied.

＜Functional layer＞ One or more functional layers can be laminated on at least one surface of the optical film of the present invention. As the functional layer, for example, an ultraviolet absorbing layer, a hard coat layer, an undercoat layer, a gas barrier layer, an adhesion layer, a hue adjustment layer, a refractive index adjustment layer, etc. may be mentioned. The functional layer can be used alone or in combination of two or more.

A hard coat layer can be provided on at least one side of the optical film of the present invention. The thickness of the hard coat layer is not particularly limited, and may be, for example, 2 to 100 μm. If the thickness of the hard coat layer is within the above range, the impact resistance can be further improved, and the bending resistance is not easily reduced, and the problem of curling caused by hardening shrinkage is not likely to occur. The hard coat layer can be formed by curing a hard coat composition containing a reactive material capable of forming a cross-linked structure by irradiation with active energy rays or by imparting thermal energy, and is preferably obtained by irradiation with active energy rays. Active energy rays are defined as energy rays that can decompose compounds that produce active species to produce active species. Examples include visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays, electron beams, etc., preferably Ultraviolet rays. The above-mentioned hard coating composition contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

The above-mentioned radically polymerizable compound is a compound having a radically polymerizable group. The radical polymerizable group possessed by the above radical polymerizable compound may be a functional group capable of undergoing a radical polymerization reaction. Examples include groups containing a carbon-carbon unsaturated double bond. Specifically, examples include : Vinyl, (meth)acryloyl, etc. In addition, when the above-mentioned radically polymerizable compound has two or more radically polymerizable groups, the radically polymerizable groups may be the same or different. In terms of increasing the hardness of the hard coat layer, the number of the radical polymerizable groups that the radical polymerizable compound has in one molecule is preferably 2 or more. As the above-mentioned radically polymerizable compound, in terms of the level of reactivity, a compound having a (meth)acryloyl group can be preferably mentioned. Specifically, there can be mentioned: 2 to 6 ( (Meth)acrylic acid is a compound called multifunctional acrylate monomer, or called epoxy (meth)acrylate, (meth)acrylate urethane, polyester (meth)acrylic acid The ester has several (meth)acrylic acid groups in the molecule and the molecular weight is hundreds to thousands of oligomers, which can be preferably cited: selected from epoxy (meth)acrylates, (meth)acrylic amines One or more of carbamate and polyester (meth)acrylate.

The above-mentioned cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. In terms of increasing the hardness of the hard coat layer, the number of cationically polymerizable groups contained in the above-mentioned cationically polymerizable compound per molecule is preferably 2 or more, more preferably 3 or more. In addition, as the above-mentioned cationically polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferred. In terms of small shrinkage accompanying the polymerization reaction, cyclic ether groups such as epoxy groups and oxetanyl groups are preferred. In addition, the compound having the epoxy group in the cyclic ether group has the following advantages: it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained hard coat layer, and is easy to control and free radically polymerizable compounds. The compatibility. In addition, the oxetanyl group in the cyclic ether group has the following advantages: Compared with the epoxy group, the degree of polymerization is easier to increase, the toxicity is lower, and the obtained hard coat cation polymerizable compound is faster. The formation speed of the network structure, even in the region where the radical polymerizable compound is mixed, will not leave unreacted monomers in the film, thereby forming an independent network structure. Examples of the cationic polymerizable compound having an epoxy group include: polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or by using a compound containing a cyclohexene ring and a cyclopentene ring with hydrogen peroxide, Cycloaliphatic epoxy resin obtained by epoxidation of appropriate oxidizing agent such as peracid; aliphatic polyol, or polyglycidyl ether of its alkylene oxide adduct, polyglycidyl ester of aliphatic long-chain polybasic acid, ( Aliphatic epoxy resins such as homopolymers and copolymers of glycidyl methacrylate; by bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or their alkylene oxide adducts , Glycidyl ether produced by the reaction of derivatives such as caprolactone adducts and epichlorohydrin, and novolac epoxy resins, that is, glycidyl ether type epoxy resins derived from bisphenols.

The above-mentioned hard coat composition may further contain a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and the like, which can be appropriately selected and used. The polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate free radicals or cations to cause radical polymerization and cationic polymerization to proceed. The radical polymerization initiator may release a substance that initiates radical polymerization by at least any one of active energy ray irradiation and heating. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and perbenzoic acid, azo compounds, such as azobisbutyronitrile, etc. are mentioned. As active energy ray radical polymerization initiators, there are the following types: Type1 radical polymerization initiators that generate free radicals by the decomposition of molecules, and free radical polymerization initiators that coexist with tertiary amines by hydrogen abstraction reaction. The base Type2 radical polymerization initiator, which can be used alone or together. The cationic polymerization initiator may release a substance that initiates cationic polymerization by at least one of active energy ray irradiation and heating. As the cationic polymerization initiator, aromatic iodonium salts, aromatic sulfonium salts, cyclopentadienyl iron (II) complexes, and the like can be used. Depending on the structure, it is possible to start cationic polymerization by either active energy ray irradiation or heating, or both active energy ray irradiation or heating can start cationic polymerization.

The polymerization initiator may preferably be contained in an amount of 0.1 to 10% by mass relative to 100% by mass of the entire hard coating composition. If the content of the above-mentioned polymerization initiator is within the above-mentioned range, the curing can often be carried out sufficiently, the mechanical properties or adhesion of the finally obtained coating film can be in a good range, and the curing shrinkage is not easy to occur. Poor adhesion or cracking phenomenon and crimping phenomenon.

The above-mentioned hard coating composition may further include one or more selected from the group consisting of solvents and additives. The above-mentioned solvent can dissolve or disperse the above-mentioned polymerizable compound and polymerization initiator. As long as it is a solvent known in the technical field as a solvent for a hard coating composition, it can be used within a range that does not hinder the effects of the present invention. . The above-mentioned additives may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The ultraviolet absorbing layer is a layer with ultraviolet absorbing function, for example, it includes: a main material selected from ultraviolet curable transparent resin, electron beam curable transparent resin, and thermosetting transparent resin; and ultraviolet absorber dispersed in the main material In the material.

The adhesive layer is a layer with adhesive function, and has the function of adhering the optical film to other components. As the forming material of the adhesive layer, generally known ones can be used. For example, a thermosetting resin composition or a photocuring resin composition can be used. In this case, the resin composition can be polymerized and cured by supplying energy afterwards.

The adhesive layer may be a layer that is called a pressure sensitive adhesive (PSA) that is adhered to an object by pressing. Pressure-sensitive adhesives can be adhesives, that is, "substances that are adhesive at room temperature and adhere to the material to be bonded with a small pressure" (JIS K 6800), or they can be capsule adhesives, that is, "protective film" (Microcapsules) contain specific components and can maintain stability until the film is broken by an appropriate method (pressure, heat, etc.)" (JIS K 6800).

The hue adjustment layer is a layer with a hue adjustment function, and is a layer that can adjust the layered body including the optical film to the target hue. The hue adjusting layer is, for example, a layer containing resin and coloring agent. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, red lead, titanyl calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; azo compounds, quinacridone compounds, anthracene Organic pigments such as quinone-based compounds, perylene-based compounds, isoindolinone-based compounds, phthalocyanine-based compounds, quinophthalone-based compounds, anthracene (Threne)-based compounds, and diketopyrrolopyrrole-based compounds; barium sulfate, and The extender pigment of calcium carbonate; and dyes such as basic dyes, acid dyes, and mordant dyes.

The refractive index adjustment layer is a layer having a refractive index adjustment function, and has, for example, a refractive index different from that of an optical film, and can give a specific refractive index to the optical laminate. The refractive index adjustment layer may be, for example, a resin layer containing appropriately selected resins and pigments as appropriate, or may be a thin film of metal. Examples of pigments for adjusting refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average primary particle size of the pigment may be 0.1 μm or less. By setting the average primary particle diameter of the pigment to 0.1 μm or less, the diffuse reflection of the light passing through the refractive index adjustment layer can be prevented, thereby preventing the decrease in transparency. Examples of metals used for the refractive index adjustment layer include titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. Such as metal oxides or metal nitrides.

In a preferred embodiment of the present invention, the optical film of the present invention is used as the front panel of the image display device, the front panel of the flexible display device (window film), the front panel of the rollable display or the foldable display. it works. The flexible display device has, for example, a flexible functional layer and an optical film that overlaps the flexible functional layer and functions as a front panel. That is, the front panel of the flexible display device is arranged on the visible side above the flexible functional layer. The front panel has the function of protecting the flexible functional layer, such as the image display element in the flexible display.

Examples of image display devices include televisions, smart phones, mobile phones, car navigation, tablet PCs (pesonal computers, personal computers), portable game consoles, electronic paper, scales, indicator boards, clocks, and smarts. Wearable devices such as type watches, etc. As the flexible display device, all image display devices having flexibility can be cited.

[Flexible display device] The present invention also provides a flexible display device provided with the optical film of the present invention. The optical film of the present invention is preferably used as a front panel in a flexible display device, and the front panel is sometimes called a window film. The flexible display device includes a laminate for a flexible display device and an organic EL display panel, and the laminate for a flexible display device is arranged on the visible side relative to the organic EL display panel, and is configured to be bendable. The laminate for a flexible display device may contain the optical film (window film) of the present invention, a circular polarizing plate, and a touch sensor. The polarizing plate, touch sensor or window film, touch sensor, circular polarizing plate are laminated in the order. If there is a circular polarizer on the visual recognition side of the touch sensor, it is difficult to visually recognize the pattern of the touch sensor, and the visibility of the displayed image becomes better, which is better. Each member can be laminated using adhesives, adhesives, etc. In addition, it may have a light-shielding pattern formed on at least one surface of any layer of the window film, the circular polarizer, and the touch sensor.

[Polarizer] The flexible display device of the present invention may further include a polarizing plate, preferably a circular polarizing plate. The circularly polarizing plate is a functional layer having the function of laminating a λ/4 retardation plate on the linearly polarizing plate to transmit only the right-handed circularly polarized light component or the left-handed circularly polarized light component. For example, it is used for the following purposes: converting external light into right-handed circularly polarized light, blocking the outer boundary light of the left-handed circularly polarized light reflected by the organic EL panel, and transmitting only the light-emitting component of the organic EL, thereby suppressing reflection The effect of light makes it easy to observe the image. In order to achieve the circularly polarized light function, the absorption axis of the linear polarizer and the late axis of the λ/4 retardation plate need to be 45° in theory, but 45±10° in practice. The linear polarizing plate and the λ/4 retardation plate do not necessarily need to be laminated adjacently, and the relationship between the absorption axis and the slow phase axis only needs to satisfy the above range. It is preferable to realize complete circularly polarized light at all wavelengths, but it is not necessary for practical use. Therefore, the circular polarizing plate in the present invention also includes an elliptical circular polarizing plate. It is also preferable to laminate a λ/4 retardation film on the visibility side of the linear polarizing plate to make the emitted light circularly polarized light, thereby improving the visibility in the state of wearing polarized sunglasses.

The linear polarizer is a functional layer with the function of passing light that vibrates in the direction of the transmission axis, but blocking the polarization of the vibration component perpendicular to it. The above-mentioned linear polarizing plate may be a composition of a linear polarizing element alone, or a composition having a linear polarizing element and a protective film attached to at least one surface thereof. The thickness of the linear polarizer may be 200 μm or less, preferably 0.5-100 μm. If the thickness is within the above range, the flexibility may not easily decrease. The linear polarizing element may be a film-type polarizing element manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film. Dichroic dyes such as iodine can be adsorbed to the PVA-based film aligned by stretching, or the dichroic dyes such as iodine can be stretched while being adsorbed on PVA to align the dichroic dyes, thereby exhibiting polarization performance. When manufacturing the above-mentioned film-type polarizing element, it may additionally have steps such as swelling, cross-linking with boric acid, washing with aqueous solution, and drying. The stretching or dyeing step may be performed alone with a PVA-based film, or may be performed in a state where it is laminated with other films such as polyethylene terephthalate. The thickness of the PVA-based film used is preferably 10-100 μm, and the stretching ratio is preferably 2-10 times. Furthermore, as another example of the above-mentioned polarizing element, a liquid crystal coating type polarizing element formed by coating a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The above-mentioned liquid crystalline compound only needs to have the property of exhibiting a liquid crystal state, and it is particularly preferable if it has a high-order alignment state equal to the smectic order, since it can exhibit high polarization performance. Moreover, it is also preferable that the liquid crystal compound has a polymerizable functional group.

The dichroic dye is a dye that is aligned together with the liquid crystal compound to exhibit dichroism. The dichroic dye itself may have liquid crystallinity or may have a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group. The above-mentioned liquid crystal polarizing composition may further include a starter, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The above-mentioned liquid crystal polarizing layer is manufactured by coating a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer. The liquid crystal polarizing layer can be formed to be thinner than the film-type polarizing element. The thickness of the above-mentioned liquid crystal polarizing layer may preferably be 0.5-10 μm, more preferably 1-5 μm. The above-mentioned alignment film can be manufactured by, for example, coating an alignment film forming composition on a substrate, and performing rubbing, polarized light irradiation, etc. to impart alignment properties. In addition to the alignment agent, the aforementioned alignment film forming composition may also include a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the above-mentioned alignment agent, for example, polyvinyl alcohols, polyacrylates, polyamides, and polyimines can be used. In the case of applying optical alignment, it is preferable to use an alignment agent containing a cinnamate group. The weight average molecular weight of the polymer used as the above-mentioned alignment agent can be about 10,000-1,000,000. From the viewpoint of the alignment restriction force, the thickness of the alignment film is preferably 5 to 10,000 nm, and more preferably 10 to 500 nm. The liquid crystal polarizing layer may be peeled from the base material and transferred to be laminated, or the base material may be laminated directly. The above-mentioned base material also preferably functions as a transparent base material for a protective film, a phase difference plate, and a window film.

As the above-mentioned protective film, any transparent polymer film may be used. Specifically, the polymer film used includes polyethylene, polypropylene, polymethylpentene, and those containing norene or cycloolefin. Polyolefins such as cycloolefin derivatives of monomer units, (modified) celluloses such as diacetyl cellulose, triacetyl cellulose, propylene cellulose, and methyl methacrylate (co)polymers Acrylics, polystyrenes such as styrene (co)polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, ethylene-vinyl acetate copolymers, polychlorine Ethylene, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate and other polyesters, nylon, etc. Polyamides, polyimines, polyamides, polyetherimines, polyethers, polyvinyl alcohols, polyvinyl acetals, polyamines Films such as formates and epoxy resins, in terms of excellent transparency and heat resistance, preferably include polyamides, polyamides, polyimines, polyesters, olefins, Acrylic or cellulose film. These polymers can be used alone or in combination of two or more kinds. These films can be used in an unstretched state, or used in the form of uniaxially or biaxially stretched films. Preferred are cellulose-based films, olefin-based films, acrylic-based films, and polyester-based films. It may also be a coating type protective film obtained by applying and curing a cationic curing composition such as epoxy resin or a radical curing composition such as acrylate. It may optionally contain plasticizers, ultraviolet absorbers, infrared absorbers, coloring agents such as pigments or dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, and slip agents , Solvents, etc. The thickness of the protective film may be 200 μm or less, preferably 1-100 μm. If the thickness of the protective film is within the above range, the flexibility of the protective film will not easily decrease.

The above-mentioned λ/4 retardation plate is a film that provides a λ/4 retardation in a direction orthogonal to the traveling direction of incident light (in-plane direction of the film). The above-mentioned λ/4 retardation plate may be a stretched retardation plate obtained by stretching a polymer film such as a cellulose-based film, an olefin-based film, or a polycarbonate-based film. It may optionally contain phase difference adjusters, plasticizers, ultraviolet absorbers, infrared absorbers, pigments or dyes and other coloring agents, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, Antioxidants, lubricants, solvents, etc. The thickness of the above-mentioned extended phase difference plate may be 200 μm or less, preferably 1-100 μm. If the thickness is within the above range, the flexibility of the film may not easily decrease. Furthermore, as another example of the above-mentioned λ/4 retardation plate, a liquid crystal coating type retardation plate formed by coating a liquid crystal composition may be used. The above-mentioned liquid crystal composition contains a liquid crystal compound, and the liquid crystal compound has the property of showing a liquid crystal state such as nematic, cholesteric, and smectic. Any compound including the liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal coating type retardation plate may further include a starter, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be manufactured by applying a liquid crystal composition on an alignment film and curing it to form a liquid crystal retardation layer in the same manner as in the description of the liquid crystal polarizing layer. The liquid crystal coating type retardation plate can be formed to be thinner than the extension type retardation plate. The thickness of the above-mentioned liquid crystal polarizing layer can usually be 0.5-10 μm, preferably 1-5 μm. The liquid crystal coating type retardation plate may be peeled from the base material and transferred and laminated, or the base material may be laminated directly. The above-mentioned base material also preferably functions as a transparent base material for a protective film, a phase difference plate, and a window film.

Generally speaking, the shorter the wavelength, the greater the birefringence, and the longer the wavelength, the smaller the birefringence. In this case, the phase difference of λ/4 cannot be achieved in the full visible light region, so in most cases it is designed to have a phase difference of λ/4 relative to the vicinity of 560 nm where the visual sensitivity is higher, that is, 100-180 nm, Preferably it is 130-150 nm. It is preferable to use an inverse dispersion λ/4 retardation plate, that is, a material with a birefringence wavelength dispersion characteristic that is opposite to the usual one, which can improve the visibility. As such a material, it is also preferable to use the one described in Japanese Patent Laid-Open No. 2007-232873 etc. in the case of an extended retardation plate, and it is also preferable in the case of a liquid crystal coating type retardation plate. The ones described in Japanese Patent Laid-Open No. 2010-30979 are used. In addition, as another method, a technique of obtaining a wide-band λ/4 retardation plate by combining with a λ/2 retardation plate is also known (Japanese Patent Laid-Open No. 10-90521). The λ/2 retardation plate is also manufactured using the same materials and methods as the λ/4 retardation plate. The extension type retardation plate and the liquid crystal coating type retardation plate can be combined arbitrarily, and the liquid crystal coating type retardation plate can be used to reduce the thickness, so it is preferable. Regarding the above-mentioned circular polarizing plate, in order to improve the visibility in the oblique direction, a method of laminating positive C plates is also known (Japanese Patent Laid-Open No. 2014-224837). The same applies to the positive type C plate, and both the liquid crystal coating type retardation plate and the extended type retardation plate can be used. The phase difference in the thickness direction is usually -200 to -20 nm, preferably -140 to -40 nm.

[Touch Sensor] The flexible display device of the present invention may further include a touch sensor. The touch sensor is used as an input mechanism. As a touch sensor, various styles such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and an electrostatic capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacitance method is preferred. The capacitive touch sensor is divided into an active area and an inactive area located outside the active area. The active area is the area corresponding to the area on the display panel (display part) that senses the user's touch, and the inactive area is the area corresponding to the area (non-display part) where no picture is displayed in the display device . The touch sensor may include: a substrate, which has flexible characteristics; a sensing pattern, which is formed in the active area of the substrate; each sensing line, which is formed in the inactive area of the substrate, is used to pass through the sensing pattern and The pad part is connected with the external driving circuit. As a substrate having flexibility, the same material as the above-mentioned polymer film can be used. Regarding the substrate of the touch sensor, in terms of suppressing cracks of the touch sensor, it is preferably a substrate with a toughness of 2,000 MPa% or more. The toughness can also be more preferably 2,000 to 30,000 MPa%. Here, the toughness is defined as the area under the curve up to the breaking point in the stress-strain curve obtained by the tensile test of the polymer material.

The aforementioned sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in directions different from each other. The first pattern and the second pattern are formed on the same layer. In order to sense the location to be touched, each pattern must be electrically connected. The first pattern is a form in which the unit patterns are connected to each other via a joint, but the second pattern is a structure in which the unit patterns are separated from each other in the form of islands. Therefore, in order to electrically connect the second pattern, another bridge electrode is required. The sensing pattern can use well-known transparent electrode materials. Examples include: indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), cadmium tin oxide ( CTO), PEDOT (poly(3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, etc., which can be used alone or Mix two or more types. ITO can be preferably used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These etc. can be used individually or in mixture of 2 or more types.

The bridging electrode can be formed on the upper insulating layer through the insulating edge layer on the upper part of the sensing pattern, and the bridging electrode can be formed on the substrate, and the insulating layer and the sensing pattern can be formed on the bridging electrode. The above-mentioned bridge electrode can be formed with the same raw material as the sensing pattern, or can be formed with metals such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them. The first pattern and the second pattern must be electrically insulated, so an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer can also be formed only between the joints of the first pattern and the bridging electrodes, or can be formed in the structure of the layer covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern via a contact hole formed in the insulating layer. The above-mentioned touch sensor may further include an optical adjustment layer between the substrate and the electrode to appropriately compensate for the difference in transmittance between the patterned area with the pattern and the non-patterned area without the pattern. For the mechanism of the difference in light transmittance induced by the difference in refractive index in the same region, the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment layer can be formed by coating a photo-curing composition containing a photo-curing organic adhesive and a solvent on a substrate. The above-mentioned photocurable composition may further contain inorganic particles. The above-mentioned inorganic particles can increase the refractive index of the optical adjustment layer. The photocurable organic adhesive may include, for example, copolymers of monomers such as acrylate monomers, styrene monomers, and carboxylic acid monomers. The photocurable organic binder may be, for example, a copolymer containing repeating units that are different from each other, such as epoxy group-containing repeating units, acrylate repeating units, and carboxylic acid repeating units. The above-mentioned inorganic particles may include, for example, zirconium oxide particles, titanium oxide particles, aluminum oxide particles, and the like. The above-mentioned photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing auxiliary agent.

[Next layer] The layers (window film, polarizing plate, touch sensor) and the film members (linear polarizing plate, λ/4 phase difference plate, etc.) constituting each layer forming the above-mentioned laminated body for flexible display devices can be bonded with an adhesive. As the adhesive, water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curing adhesives, heat-curing adhesives, and anaerobic-curing adhesives can be used. Adhesives, water-based solvent volatile adhesives, active energy ray hardening adhesives, hardener mixed adhesives, hot melt adhesives, pressure sensitive adhesives (adhesives), rewetting adhesives, etc. Among them, water-based solvent volatile adhesives, active energy ray hardening adhesives, and adhesives are often used. The thickness of the adhering layer can be appropriately adjusted according to the obtained adhesive force, etc., and is, for example, 0.01 to 500 μm, preferably 0.1 to 300 μm. The adhesive layer may have a plurality of layers in the above-mentioned flexible image display device laminate, but the thickness of each and the type of adhesive used may be the same or different.

As the above-mentioned water-based solvent-volatile adhesive, water-dispersed polymers such as polyvinyl alcohol-based polymers, starches and other water-soluble polymers, ethylene-vinyl acetate emulsions, styrene-butadiene emulsions, and other water-dispersed polymers can be used as the main Agent polymer. In addition to water and the above-mentioned main agent polymer, crosslinking agents, silane-based compounds, ionic compounds, crosslinking catalysts, antioxidants, dyes, pigments, inorganic fillers, organic solvents, etc. can also be formulated. In the case of bonding using the water-based solvent-volatile adhesive, the water-based solvent-volatile adhesive may be injected between the layers to be bonded to bond the bonded layers, and then dried to impart adhesiveness. In the case of using the above-mentioned water-based solvent-volatile adhesive, the thickness of the adhesive layer may be 0.01-10 μm, preferably 0.1-1 μm. When the above-mentioned water-based solvent-volatile adhesive is used to form multiple layers, the thickness of each layer and the type of the above-mentioned adhesive may be the same or different.

The active energy ray curable adhesive can be formed by irradiating an active energy ray to harden an active energy ray curable composition, and the active energy ray curable composition includes a reactive material that forms an adhesive layer. The active energy ray hardening composition may contain at least one polymer of the same radical polymerizable compound and cation polymerizable compound as the hard coating composition. The above-mentioned radically polymerizable compound is the same as the hard-coat composition, and the same type as the hard-coat composition can be used. As the radically polymerizable compound used for the adhesive layer, a compound having an acrylic group is preferred. In order to reduce the viscosity of the adhesive composition, it is also preferable to include a monofunctional compound.

The above-mentioned cationically polymerizable compound is the same as the hard coat composition, and the same type as the hard coat composition can be used. The cationic polymerizable compound used in the active energy ray hardening composition is more preferably an epoxy compound. In order to reduce the viscosity of the adhesive composition, it is also preferable to include a monofunctional compound as a reactive diluent. The active energy ray composition may further include a polymerization initiator. As the polymerization initiator, there are radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc., which can be appropriately selected and used. The polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate free radicals or cations to cause radical polymerization and cationic polymerization to proceed. In the description of the hard coating composition, an initiator that can start at least one of radical polymerization and cationic polymerization by irradiation with active energy rays can be used.

The active energy ray hardening composition may further include an ion scavenger, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, a fluid viscosity adjuster, a plasticizer, a defoamer solvent, an additive, and a solvent. In the case of bonding by the above-mentioned active energy ray-curing adhesive, bonding can be performed by the following method: the above-mentioned active energy ray-curing composition is applied to any one or both of the layers to be bonded and then bonded, It is hardened by irradiating active energy rays through either the bonded layer or the two bonded layers. In the case of using the above-mentioned active energy ray-curable adhesive, the thickness of the adhesive layer can usually be 0.01-20 μm, preferably 0.1-10 μm. When the active energy ray-curable adhesive is used to form multiple layers, the thickness of each layer and the type of adhesive used may be the same or different.

The above-mentioned adhesives are classified into acrylic adhesives, urethane adhesives, rubber-based adhesives, silicone-based adhesives, etc. according to the main agent polymer, and any of them can be used. In addition to the main agent polymer, crosslinking agents, silane-based compounds, ionic compounds, crosslinking catalysts, antioxidants, adhesion imparting agents, plasticizers, dyes, pigments, inorganic fillers, etc. can also be formulated in the adhesive. Each component constituting the adhesive is dissolved and dispersed in a solvent to obtain an adhesive composition, and the adhesive composition is applied on a substrate and dried to form an adhesive layer (adhesive layer). The adhesive layer can be formed directly, or it can be transferred on the substrate. In order to cover the adhesive surface before bonding, it is also preferable to use a release film. In the case of using the above-mentioned adhesive, the thickness of the adhesive layer can usually be 1 to 500 μm, preferably 2 to 300 μm. When the above-mentioned adhesive is used to form multiple layers, the thickness of each layer and the type of adhesive used may be the same or different.

[Shading Pattern] The light-shielding pattern can be used as at least a part of the frame or housing of the flexible image display device. With the light-shielding pattern, the wiring arranged in the edge portion of the flexible image display device is hidden and is not easily recognized, thereby improving the visibility of the image. The above-mentioned light-shielding pattern may be in the form of a single layer or a multiple layer. The color of the shading pattern is not particularly limited, and can have various colors such as black, white, and metallic. The light-shielding pattern can be formed by pigments used to present colors, and polymers such as acrylic resins, ester resins, epoxy resins, polyurethanes, and silicones. These can be used alone or as a mixture of two or more kinds. The above-mentioned light-shielding pattern can be formed by various methods such as printing, offset printing, and inkjet. The thickness of the light-shielding pattern is usually 1-100 μm, preferably 2-50 μm. Moreover, it is also preferable to give a shape such as an inclination in the thickness direction of the light-shielding pattern. [Example]

Hereinafter, the present invention will be described in further detail with examples. As long as there is no special record, "%" and "parts" in the examples mean mass% and mass parts, respectively. First, the method of measuring physical property values will be described.

＜Weight average molecular weight＞ The weight average molecular weight of the resin is measured by gel permeation chromatography (GPC). The preparation method and measurement conditions of the measurement sample are as follows. (1) Sample preparation method Weigh 20 mg of resin and add 10 mL of DMF (10 mmol/L lithium bromide) to completely dissolve it. This solution was filtered with a chromatography disk (pore size 0.45 μm) to prepare a sample solution. (2) Measurement conditions Device: HLC-8020GPC Column: protection column+TSKgelα-M(300 mm×7.8 mm diameter)×2+α-2500(300 mm×7.8 mm diameter)×1 Eluent: DMF (add 10 mmol/L lithium bromide) Flow rate: 1.0 mL/min Detector: RI (Refractive Index, refractive index) detector Column temperature: 40℃ Injection volume: 100 μL Molecular weight standard: standard polystyrene

＜Thickness＞ For the optical films obtained in the Examples and Comparative Examples, an ABS digital scale ("ID-C112BS" manufactured by Mitutoyo Co., Ltd.) was used to measure the thickness of the optical film.

＜Elastic modulus＞ A dumbbell cutter was used to cut the optical films obtained in the Examples and Comparative Examples into short strips of 10 mm×100 mm to obtain test samples. For the elastic modulus of the test sample, the Autograph AG-IS manufactured by Shimadzu Corporation was used to measure the stress-strain curve (SS curve) at a distance between the chucks of 50 mm and a tensile speed of 10 mm/min. Calculate the elastic modulus (GPa) of the optical film based on the gradient of the stress under 5-20 MPa.

＜Bending test＞ A dumbbell cutter was used to cut the films obtained in the Examples and Comparative Examples into a size of 10 mm×100 mm. At this time, for Examples 1 and 2, the film was cut so that the TD direction was the long side. For the comparative example, the film was cut so that the longitudinal direction of the film was the long side. Set the cut film on the main body of the MIT flexural fatigue testing machine ("MIT-DA" manufactured by Toyo Seiki Co., Ltd., model: 0530), at a test speed of 175 cpm, a bending angle of 135°, and a load of 750 g. Under the condition that the R of the bending jig is 1.0 mm, carry out the bending test in both directions to measure the bending resistance of each film (the number of bending without breaking). Furthermore, in this example, the bending in the MD direction was evaluated.

<Raman spectrometry> (Production of measurement sample) The film obtained in the examples and comparative examples was cut into a size of 2 mm×5 mm using a cutter. At this time, for Examples 1 and 2, the film was cut so that the TD direction was the long side. For the comparative example, the film was cut so that the longitudinal direction of the film was the long side. The cut section is placed on the surface, and embedding is performed with epoxy resin type 53 (manufactured by Acura) at room temperature. The cross-section side of the optical laminate is processed by the ultra-thin microtome EM UC7 (manufactured by Leica) to make the cross-section. (Raman spectroscopy measurement) For the cut film, use NRS-5100 manufactured by JASCO Corporation. Under the conditions shown below, at the center, 1/4 point, 1/2 point, in the thickness direction of the film, Raman spectroscopy was performed at 3/4 locations. Furthermore, after focusing on the surface of the film, irradiate the laser for more than 2 minutes, and start the measurement when the reference line is stable. In addition, the point on the surface in contact with the PET substrate is set to D ₀ . According to the obtained results, read the intensity of the largest peak in the range of ^{1,550-1,650 cm -1.} (Measurement conditions) Exposure time: 10 seconds Cumulative times: 2 times Excitation wavelength: 532.23 nm Spectrometer: Single beam Slit width: 100×1000 μm Resolution: 13.80 cm ^-1 , 3.64 cm ^-1 / Pixel objective lens: MPLFLN 100 × Laser intensity: 2.6 mW Dimmer: 50% (OD0.3)

＜Preparation of silica sol＞ Add 442.6 g of methanol-dispersed silica sol (average primary particle size of 27 nm, solid content of silica particles 30.5%) and GBL 301.6 g to a 1,000 mL flask, and use a vacuum evaporator at 45°C in a hot water bath at 400 The methanol was evaporated for 1 hour at hPa and for 1 hour at 250 hPa. Furthermore, the temperature was raised to 70°C at 250 hPa and heated for 30 minutes to obtain GBL dispersed silica sol 1. The solid content concentration of the obtained GBL dispersed silica sol 1 was 29.1%.

<Synthesis Example 1: Preparation of polyamide imine resin (1)> Nitrogen is introduced into a fully dried reaction vessel equipped with a stirrer and a thermometer, and the inside of the vessel is replaced with nitrogen. Add 1907.2 parts by mass of dimethylacetamide (DMAc) to the reaction vessel, and add 111.94 parts by mass of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 4,4'-(hexafluoro 46.84 parts by mass of isopropylidene) diphthalic dianhydride (6FDA) were reacted. Then, 10.37 parts by mass of 4,4'-oxybis(benzyl chloride) (OBBC) and 42.79 parts by mass of terephthalate chloride (TPC) were added and reacted. Then, 37.66 parts by mass of anhydrous acetic acid was added, and after stirring for 15 minutes, 11.45 parts by mass of 4-picoline was added, and the reaction vessel was heated to 70° C. and stirred for 3 hours to obtain a reaction liquid. The reaction liquid was cooled, 3794.5 parts by mass of methanol was added, and then 1419.4 parts by mass of ion-exchanged water was added dropwise to precipitate a white solid. The precipitated white solid was captured by centrifugal filtration and washed with methanol to obtain a wet cake containing polyimide resin. The obtained wet cake was dried at 78° C. under reduced pressure to obtain polyimide resin powder. The weight average molecular weight of the obtained polyimide resin (1) was 466,000.

<Example 1> (Manufacturing of resin composition 1) Add GBL Dispersed Surface Modified Silica Sol 1 to GBL solvent at room temperature, stir and mix thoroughly, and add Sumisorb to it at 5.7 parts by mass and 35 ppm, respectively, relative to 100 parts by mass of the resin and silica particles. (Registered trademark) 340 [2-(2-hydroxy-5-third octylphenyl) benzotriazole, manufactured by Sumika Chemtex (stock)] and Sumiplast (registered trademark) Violet B (blueing agent, Sumika Chemtex ( Stock) manufacturing), and mixed. Thereafter, the polyamide imide resin (1) was added and mixed so that the composition ratio of the resin and the silica particles was 60:40, and the mixture was stirred until uniform, thereby obtaining a resin composition with a solid content of 10% by mass 1 (Hereinafter, it may be referred to as resin varnish 1).

(Manufacturing of Optical Film 1) On a PET (polyethylene terephthalate) film ("COSMOSHINE (registered trademark) A4100" manufactured by Toyobo Co., Ltd., thickness 188 μm, thickness distribution ±2 μm), it is obtained by casting The resin varnish 1 is formed into a coating film. At this time, the line speed is 0.3 m/min. In addition, after heating at 80°C for 10 minutes, heating at 100°C for 10 minutes, then heating at 90°C for 10 minutes, and finally heating at 80°C for 10 minutes, and drying the coating under these conditions. After that, the coating film was peeled from the PET film to obtain a raw film 1 having a thickness of 58 μm and a width of 700 mm. A tenter dryer (consisting of 1 to 6 chambers) equipped with a clip as a holder is used to heat the obtained raw film 1 to remove the solvent, and a resin film 1 with a thickness of 49.5 μm is obtained. At this time, the conditions in the drying furnace are adjusted as follows: the temperature in the drying furnace is 200℃, the holding width of the clamp is 25 mm, the film conveying speed is 0.9 m/min, and the film width at the exit of the drying furnace is relative to the film width at the entrance of the drying furnace. The ratio of (distance between clips) is 0.98. Adjust the wind speed in each chamber of the stenter dryer to: 13.5 m/s for 1 chamber, 13 m/s for 2 chambers, and 11 m/s for 3 to 6 chambers . Hot air is blown from above and below the film. The Raman spectroscopic measurement, elastic modulus, and bending resistance of the cross section of the obtained resin film 1 were evaluated.

<Example 2> (Manufacturing of resin composition 2) Add polyimide imine resin (1) to GBL solvent at room temperature, stir and mix well, and add Sumisorb 340 to it at 5.7 parts by mass and 35 ppm, respectively, with respect to 100 parts by mass of the resin. [2-(2-hydroxy-5-tertiary octylphenyl)benzotriazole, manufactured by Sumika Chemtex Co., Ltd.] and Sumiplast Violet B (bluing agent, manufactured by Sumika Chemtex Co., Ltd.), and mixed. The mixture was stirred until it was uniform to obtain a resin composition 2 (hereinafter, sometimes referred to as resin varnish 2) having a solid content of 15% by mass.

(Manufacturing of Optical Film 2) Use resin varnish 2 as the resin varnish, and use a polyethylene terephthalate (PET) film with a thickness of 198 μm on both sides of the substrate with a hard coat (HC) layer (PET + both sides with a thickness of 188 μm with easy-to-adhesive layers on both sides) On the hard coat layer with a thickness of 5 μm, the Martens hardness of the film forming surface side and the opposite side (ie, the hard coat surface side) is 410 N/mm). Other than that, the same method as in Example 1 was used. A resin film 2 with a thickness of 49.5 μm is obtained. The Raman spectroscopy, elastic modulus, and bending resistance of the cross section of the obtained resin film 2 were evaluated.

<Comparative example 1> (Manufacturing of resin composition 3) Add GBL dispersion surface-modified silica sol 1 to GBL solvent at room temperature and stir and mix thoroughly. After that, add polyimide imide resin (1) in such a way that the composition ratio of resin and silica particles is 60:40. ) And mix them. It stirred until it was uniform, and obtained the resin composition 3 (Hereinafter, it may be called resin varnish 3) with a solid content of 8.6% by mass.

(Manufacturing of Optical Film 3) On the smooth surface of a PET (polyethylene terephthalate) film ("COSMOSHINE A4100" manufactured by Toyobo Co., Ltd., thickness 188 μm, thickness distribution ±2 μm), the thickness of the self-supporting film is 55 μm Method Use an applicator to coat the obtained resin varnish 3, dry at 50°C for 30 minutes, and then at 140°C for 15 minutes, then peel the obtained coating film from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and a fully exhausted oven (manufactured by ESPEC Co., Ltd.) was used as a dryer, and then dried in the atmosphere at 200° C. for 40 minutes to obtain a resin film 3 with a thickness of 50 μm. At this time, regarding the conditions in the drying furnace, the temperature in the drying furnace is 200°C, and the side surface of the film is fixed with a metal frame so that the film does not shrink (stretching ratio is 1 times). The hot air is blown from the transverse direction of the film (the direction perpendicular to the cross section of the thickness direction). The Raman spectroscopy measurement, elastic modulus, and bending resistance of the cross section of the obtained resin film 3 were evaluated.

＜Comparative example 2＞ (Manufacturing of Resin Composition 4) Add polyamide imide resin (1) to GBL solvent at room temperature, stir and mix well, to obtain resin composition 4 (hereinafter, sometimes referred to as resin varnish 4) with a solid content of 9% by mass .

(Manufacturing of Optical Film 4) Except for using the resin varnish 4 as the resin varnish, the same method as in Comparative Example 1 was used to obtain a resin film 4 having a thickness of 50 μm. The Raman spectroscopic measurement, elastic modulus, and bending resistance of the cross section of the obtained resin film 4 were evaluated.

For the optical films obtained in Examples and Comparative Examples, the above-mentioned items were measured, and the results are shown in Table 1. Furthermore, although it is not described in Table 1, in the optical films of the Examples and Comparative Examples, I ₃ /I ₂ does not satisfy the formula (2).

[Table 1] Silica Stretching ratio Direction of hot air Center (I ₂ ) 1/4 (I ₁ ) I ₁ /I ₂ Bending times [times] Modulus of Elasticity [GPa] Example 1 Have 0.98 up and down 1770 1628 0.92 ≧25,000 7.2 2 no 0.98 up and down 2164 1061 0.49 ≧200,000 6.0 Comparative example 1 Have 1.00 horizontal 2590 2550 0.98 ＜20,000 6.5 2 no 1.00 horizontal 1723 1712 0.99 <200,000 5.2

It is confirmed that the optical film of the embodiment that satisfies at least one of the above formulas (1) and (2) has a higher bending number than the comparative examples 1 and 2 in which both formulas (1) and (2) exceed 0.97, and the elastic modulus The number is also higher. Among them, it is confirmed that it is generally difficult to increase the number of bending of optical films containing silicon oxide. However, according to the optical film of the present invention, even when silicon oxide is contained, high bending resistance can be obtained.

10: area 12: area 14: area 18: Holding device 20: Raw film 22: Resin film 30: Upper side nozzle (nozzle) 32: Lower side nozzle (nozzle) 35: Nozzle 37: IR heater 100: Tenter furnace 100a: upper surface 100b: bottom surface A: The transport direction of the film

FIG. 1 is a schematic cross-sectional view of the steps of a preferred embodiment of the manufacturing method of the optical film of the present invention. 2 is a step cross-sectional view schematically showing a preferred embodiment of the heating step in the method of manufacturing the optical film of the present invention. Fig. 3 is a schematic cross-sectional view showing a preferred embodiment in the tenter furnace in the method of manufacturing the optical film of the present invention.

Claims (10)

An optical film containing polyamide resin, the thickness of the optical film is set to A μm, the arbitrary position on one surface of the optical film is set to D ₀ , and the thickness direction is separated from _{D 0 by A} × 1/4 μm to the position D _1, and the distance in the thickness direction D ₀ A × 1/2 μm is set to the position D _2, the thickness direction of the distance D ₀ A × disposed position 3/4 μm of Is D ₃ , when the intensity of the largest peak in the range of ^{1,550-1,650 cm -1} measured by Raman spectroscopy at each position of _{D 1} ～D _{3 is set to I 1} ～I ₃ , the optical film satisfies At least one of formula (1) and formula (2): [number 3]

. The optical film of claim 1, wherein I ₁ /I ₂ satisfying the above formula (1) or I ₃ /I ₂ satisfying the above formula (2) is 0.3 or more. Such as the optical film of claim 1 or 2, wherein the elastic modulus of the optical film is 5.5 GPa or more. Such as the optical film of claim 1 or 2, wherein the total light transmittance of the optical film is more than 80%. The optical film of claim 1 or 2, wherein the weight average molecular weight of the polyamide resin is 250,000 or more. The optical film of claim 1 or 2, wherein the polyamide resin is a polyamide resin. For example, the optical film of claim 1 or 2, which is a film for the front panel of a flexible display device. A flexible display device provided with the optical film as claimed in any one of claims 1 to 7. Such as the flexible display device of claim 8, which further includes a touch sensor. For example, the flexible display device of claim 8 or 9, which is further provided with a polarizing plate.

Images