JPH09183201A - Optical film and method for producing the same - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To suppress the occurrence of visually noticeable scratches in a polyester film used for optical applications. A has a surfactant film surface, the film and its manufacturing polyester optical wherein the above length 20mm and maximum depth 0.5μm or more scratches is 10 / m ² or less Method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to various weather resistant layers, antifogging layers, hard coat layers,
The present invention relates to a base film suitable for optical use after coating or vapor deposition, sputtering or EB vapor deposition of an antireflection layer, a heat ray shielding or a reflection layer. The term "optical" as used in the present invention refers to a case of being used in a state in which light is transmitted and reflected, such as for building windows, cars, various devices, etc. for windowing, for preventing scattering on glass, etc., for covering various displays, etc. ,
The film itself, excluding the vapor deposition layer and the reflection layer, is used in a light transmitting state.

[0002]

2. Description of the Related Art Polyester films are conventionally used as various optical films because of their excellent weather resistance. Particularly, from the viewpoint of strength and the like, a biaxially stretched film, especially a relatively thick film is used.

A film used for such an optical application is required to have a particularly durable surface, and if the film surface is scratched, the commercial value and the function may be significantly impaired. The scratches on the surface of the film are not only conspicuous not only in the state of the film itself but also in small scratches when vapor deposition is performed.

[0004]

However, in the film manufacturing process, particularly when the film is traveling on various rolls, when the film is wound into a roll, or the like, between the film surface and the roll surface or the film surface. Sliding may occur between the films, and linear scratches may occur on the film surface due to the sliding.

If such scratches become noticeable visually, the film itself and the form of the final product may be impaired in commercial value or function, so that the occurrence of scratches must be suppressed as much as possible.

[0006] Therefore, an object of the present invention is to suppress the occurrence of visually noticeable scratches as much as possible in a polyester film used for a specific application, particularly an optical application.

[0007]

In order to achieve the above object, the optical film of the present invention has a surfactant on the surface of the film and has a length of 20 mm or more and a maximum depth of 0.5 μm.
It is characterized in that the number of scratches is 10 pieces / m ² or less. Where the size of the scratch is 20 mm
The above and / or the maximum depth of 0.5 μm or more are defined as visually noticeable or annoying sizes.

The method for producing an optical film according to the present invention is characterized by providing a surfactant-containing layer on at least one side of a polyester resin film.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. The optical film of the present invention is a film made of polyester resin. The polyester resin is, for example, ethylene glycol, diethylene glycol, polyethylene glycol, sebacic acid, an aliphatic glycol such as adipic acid, or an aromatic glycol such as cyclohexanedimethanol as an alcohol component, and terephthalic acid as an acid component, An aromatic dicarboxylic acid such as isophthalic acid, or a trifunctional carboxylic acid such as naphthalene dicarboxylic acid or trimellitic acid is used. These polyester resins may be used alone or may be copolymerized with other components.

A film is molded using such a polyester resin. The film may be an unstretched film or a uniaxially stretched film, but a biaxially stretched film is preferable in terms of strength and strength balance.

A surfactant-containing layer is provided on the surface of this film. The surfactant-containing layer may be in a state in which the surfactant is present on the film surface or the surfactant is deposited on the film surface, and the surfactant is contained throughout the thickness direction of the film. Any of the form and the form in which the surfactant-containing layer is present only on the film surface may be used.

By having a surfactant on the surface of the film, when the film is run on a roll or wound into a roll, a lubricating effect with the roll surface or between the film surfaces is obtained. And the film surface is less likely to be scratched.

In the present invention, the scratch on the film surface is set to a specific value or less. That is, the length is 20m
10 scratches / m or more with a maximum depth of 0.5 μm or more
Less than or equal to ² .

The size of the scratch is a size that is noticeable or annoying to the naked eye, and particularly in optical applications, the commercial value and the function are often judged by visual reference.

In order to achieve such a low value for the number of scratches, a surfactant is present on the film surface. The type of the surfactant is not particularly limited, but examples thereof include amine base type surfactants such as stearylamine hydrochloride, quaternary ammonium salt type surfactants such as stearyltrimethylammonium chloride, and anionic surfactants. As the agent, carboxylic acid type such as sodium laurate, sulfonic acid type such as sodium dodecylbenzene sulfonate, sulfate ester type such as sodium dodecyl sulfate, and phosphate ester type such as sodium dodecyl polyoxyethylene sulfate monolauryl phosphate As surfactants and nonionic surfactants, ester type such as glycerin monostearate ester, ether type such as polyoxyethylene onyl phenyl ether, ester ether type such as polyethylene glycol oleic acid ester, lauric acid diethyl ester Alkanolamide type surfactants such as amide, amphoteric surfactants such as carboxybetaine type such as lauryldimethyl acetic acid betaine, and glycine type such as 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine. Surfactants can be used.

The optical film is often formed into a product form by sputtering or vapor deposition. Even if the product has a light reflecting function, the film itself is used in an optically transparent state. Most are done. Therefore, it is preferable to keep the internal haze of the film as low as possible. For example, the internal haze (188 μ
It is preferably 1.5% or less. In order to keep the internal haze low, it is preferable that the film is substantially particle-free. However, a small amount of particles, for example, a small amount of inert fine particles may be contained in order to improve the slipperiness and the antistatic property.

In order to allow the surfactant to be present on the surface of the film, the surfactant is kneaded into the film, more precisely into the polyester resin for forming the film, and the film is formed into the film. There is a method of depositing a surfactant on the film surface by a coating method, or a method of forming a surfactant-containing layer on the film surface by coating. The latter coating method is preferable from the viewpoint of allowing a desired amount of surfactant to be efficiently present on the film surface. The surfactant-containing layer to be applied may be any of a molten resin containing a surfactant, a solution resin, and a layer composed of only a surfactant.

Further, particularly in the method of providing the surfactant-containing layer by coating, it is easy to control the thickness of the surfactant-containing layer. The thickness of the surfactant-containing layer is preferably 0.001 μm or more and 0.3 μm or less. If it is less than 0.001 μm, the lubricating effect due to the presence of a surfactant is poor, and if it exceeds 0.3 μm, the lubricating effect is saturated and a brittle surface layer is intentionally formed.

In any case of providing the surfactant-containing layer, the amount of the surfactant on the film surface is 1.5 g / in order to prevent the excessive deposition of the surfactant on the film surface. It is preferably m ² or less.

Next, a typical example of the method for producing an optical film according to the present invention will be described. If necessary, additives such as particles are added to a predetermined polyester resin to obtain a moisture content of 30.
After drying to 0 ppm or less, 200 ~ 3 using an extruder
Melt at 50 ° C and extrude. Drying may be omitted when a vented extruder is used. The molten resin is formed into a sheet on a cooling roll, biaxially stretched 2.5 to 8 times in the longitudinal direction and 2.5 to 8 times in the width direction, and then 150 to 300 ° C.
Heat treatment and relaxation treatment are performed. The method for providing the surfactant on the film surface is not particularly limited, but a method of kneading the polyester resin in advance, a method of applying the surfactant-containing layer, or a method of applying only the surfactant can be used. The method for applying the surfactant-containing layer or the surfactant is not particularly limited, and it may be applied in any state of unstretched, uniaxially stretched and biaxially stretched. However, since wide defects after width-stretching, conveyance at high speed, and occurrence of defects at the time of winding are significant, a method of applying after uniaxial stretching and then forming a biaxially stretched film is particularly preferable.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. First, the methods for measuring and evaluating the physical properties and characteristics of the present invention are shown below.

(1) Amount of surfactant on the film surface The film surface is washed with ethyl alcohol and quantified.

(2) Size and number of scratches The surface of the film is magnified 300 times with a microscope and visually observed. The length and number of scratches on the film surface are measured by the observation. Regarding the maximum depth of the scratch, a film cross-section photograph is taken, and the maximum depth is visually measured and determined from the photograph.

(3) Inner haze The surface of the film is covered with liquid paraffin, and JIS-K
6714, and converted into a film thickness of 188 μm.

(4) Appearance When a film and a glass plate were laminated and a landscape or a television screen was viewed, those with a noticeable scratch were judged as "x", and the others were judged as "○".

(5) 100 sheets of sheet-like samples of blocking film were superposed and
After leaving it for 3 days under conditions of 85 ° C and 85% RH, peel off one by one, and lightly peel off "○", otherwise "X"
It was determined.

Comparative Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was melt extruded at a moisture content of 30 ppm at 250 ° C. and a surface temperature of 4
1. After forming into a film on a chill roll at 0 ° C, 2.
It was stretched 8 times in the longitudinal direction and 3 times in the width direction at 115 ° C. to obtain a biaxially stretched film having a thickness of 188 μm. The film discharged from the widthwise stretching / heat treatment machine (stenter) is uniformly drawn on the stenter clips between the hard chrome plating rolls with a draw ratio of 1.015 and the tension cutting rolls consisting of nip rolls consisting of silicone rubber rolls.
After passing through the hard chrome-plated roll of the book, it was wound with a winder.

Examples 1 and 2 In Comparative Example 1, on the longitudinally uniaxially stretched film, the surfactant "Flasut" RY-2 manufactured by Goyo Chemical Co., Ltd. was added.
A water-soluble polyester resin added with 0.02% by weight (Example 1) and 0.1% by weight (Example 2) was applied, dried, and stretched in the width direction.

Example 3 and Comparative Example 2 A biaxially stretched film was coated with a predetermined amount of sodium dodecylbenzenesulfonate by a gravure coating method.
The other conditions are the same as in Comparative Example 1.

Example 4 A biaxially stretched film was formed under the same conditions as in Example 1 except that a resin having an intrinsic viscosity of 0.72 copolymerized with 3 mol% of cyclohexanedimethanol was used as a resin alcohol component.

Example 5 As the resin, a resin prepared by adding 0.5% of sodium dodecylbenzenesulfonate to polyethylene terephthalate copolymerized with 1% by weight of polyethylene glycol having a molecular weight of 2000 was used. The other conditions are the same as in Comparative Example 1.

Example 6 The same as Example 1 except that 0.03% by weight of aggregated silica having an average particle size of 1.5 μm was added to the resin.

Example 7 A composite layer having a thickness of 3 μm was provided on both surfaces of the film of Comparative Example 1. In the composite layer, 0.
A resin prepared by adding 0.5% by weight of sodium dodecylbenzenesulfonate to polyethylene terephthalate copolymerized with 03% by weight and 1% by weight of polyethylene glycol having a molecular weight of 2000 was used. Table 1 shows the results of Examples 1 to 7 and Comparative Examples 1 and 2.

[0034]

[Table 1]

As is clear from Table 1, the presence of a surfactant on the film surface significantly reduces the scratches of a size larger than a predetermined size. Further, by controlling the amount of the surfactant on the film surface to a predetermined amount, it is possible to suppress blocking and reduce the number of conspicuous scratches as described above.

[0036]

As described above, according to the optical film and the method for producing the same of the present invention, the presence of a surfactant on the surface of the film can significantly reduce the number of conspicuous scratches on the surface of the film. Therefore, the base film suitable for optical use can be obtained.

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Claims (14)

[Claims] 1. A polyester optical film having a surfactant on the surface of the film and having 10 or more scratches having a length of 20 mm or more and a maximum depth of 0.5 μm or more per m ² or less. 2. The optical film according to claim 1, wherein the film is a biaxially stretched film. 3. The optical film according to claim 1, wherein the film is substantially particle-free and has an internal haze (converted to 188 μm) of 1.5% or less. 4. A surfactant-containing layer having a thickness of 0.001 μm or more and 0.3 μm or less is provided on the film surface,
An optical film according to any one of claims 1 to 3. 5. The optical film according to claim 4, wherein the surfactant-containing layer is provided by coating. 6. The optical film according to claim 1, wherein the surfactant is deposited on the surface of the film by kneading into the film. 7. The optical film according to claim 1, wherein the amount of the surfactant on the surface of the film is 1.5 g / m ² or less. 8. The optical film according to claim 1, which is used in an optically transparent state. 9. A method for producing an optical film, which comprises providing a surfactant-containing layer on at least one surface of a film made of a polyester resin. 10. The method for producing an optical film according to claim 9, wherein the film is biaxially stretched. 11. The method for producing an optical film according to claim 9, wherein the surfactant-containing layer is provided by coating. 12. The method for producing an optical film according to claim 11, wherein after the polyester resin is uniaxially stretched, the surfactant-containing layer is applied onto the uniaxially stretched film, and then the uniaxially stretched film is used as the biaxially stretched film. . 13. The method for producing an optical film according to claim 12, wherein the applied surfactant-containing layer is composed of only a surfactant. 14. The method for producing an optical film according to claim 9, wherein the surfactant is kneaded in advance in the polyester resin, and the polyester resin is molded into a film.