JP2002003083A - Optical film web, its preserving method and its transporting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film web capable of reducing the transfer of a winding core, hardly causing a wrinkle at the start of winding, not producing a horse-back (U-shape deformation) failure even if it is preserved for a long time and allowing excellent productivity in manufacturing itself and to provide its preserving method and its transporting method. SOLUTION: This optical film web is characterized in that the height Rp of the center line of the surface of the winding core for winding the optical film web is 0.05-1.0 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film (hereinafter, also simply referred to as a film) used for optical applications, a method for storing and transporting the same, and particularly to a polarized light used for a liquid crystal display device and the like. Optical film base material that can be used for various functional films such as protective films for plates, retardation films, viewing angle widening films, antireflection films used for plasma displays, and various functional films used for organic EL displays, etc. The present invention relates to anti-reflection and storage and transportation methods.

[0002]

2. Description of the Related Art In recent years, the development of thin and lightweight notebook computers, large screens, and high definition has been advanced. Along with this, there is an increasing demand for thinner, wider, and higher quality protective films for liquid crystal polarizers. Generally, a cellulose ester film is widely used as a protective film for a polarizing plate. A cellulose ester film is usually wound around a core to become a film raw material, and is stored and transported.

[0003] A failure called core transfer occurs in the core of the film. In the core transfer, the film is deformed due to unevenness of the core or dust attached to the core, resulting in a failure. In a normal 80 μm cellulose ester film, the portion that could not be used for core transfer was about 10 to 20 m, so it did not pose a major problem.

However, it has been found that when the cellulose ester film is thinned, the core transfer may occur over several tens of meters, which is a serious problem.

In order to solve this problem, when the surface of the core is made smooth, it has been found that if the surface is too smooth, wrinkles are generated in the film when the film starts to be wound around the core.

Further, as the screen size increases, it is required that the width of the film raw material be wide and the winding length be long. For this reason, the film stock becomes wider and the film stock load tends to increase, and if these are stored for a long period of time, a failure called a horse back failure is likely to occur. A horse back failure is a failure in which the raw film of the film deforms into a U-shape like a horse's back, and a belt-shaped convex portion is formed near the center at a pitch of about 2 to 3 cm. Processing a polarizing plate is a problem because the surface looks distorted. Until now, horse back failures have been reduced by lowering the coefficient of kinetic friction between the bases and adjusting the height of the knurling (embossing) on both sides.

[0007]

However, the present inventor has
It has been found that the film load causes the core to bend, causing a horse back failure.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to reduce the transfer of the core, hardly cause wrinkles at the beginning of winding, and keep the horse back even after long-term storage. It is intended to provide an optical film raw material excellent in productivity that does not cause failure and its storage method, transportation method,
In particular, the effect is exhibited in a thin optical film.

[0009]

The above object of the present invention has been attained by the following constitutions.

[0010] 1. An optical film raw material characterized in that the center line peak height Rp of the surface of the core for winding the optical film raw material is 0.05 to 1.0 μm.

2. A method for preserving a raw optical film, comprising storing the raw optical film having a center line peak height Rp of 0.05 to 1.0 μm on the surface of a core for winding the raw optical film.

3. A method for transporting an optical film raw material, comprising transporting an optical film raw material having a center line peak height Rp of 0.05 to 1.0 μm on a surface of a core for winding the optical film raw material.

4. 2. The optical film raw material as described in 1 above, wherein the residual good solvent amount of the optical film raw material is 1% or less.

5. 3. The method for preserving a raw optical film according to the item 2, wherein the residual amount of the good solvent in the raw optical film is 1% or less.

6. 4. The method for transporting a raw optical film according to the item 3, wherein the residual amount of the good solvent in the raw optical film is 1% or less.

[7] 5. The raw optical film according to the item 4, wherein the residual good solvent is methylene chloride.

8. 6. The method for preserving a raw optical film according to the item 5, wherein the residual good solvent is methylene chloride.

9. 7. The method for transporting a raw optical film according to the item 6, wherein the residual good solvent is methylene chloride.

10. (1) The dynamic friction coefficient between the core surface and the raw optical film is 0.1 to 1.5.
The optical film raw material described in 1.

11. (2) the coefficient of dynamic friction between the core surface and the raw optical film is 0.1 to 1.5.
The method for preserving an optical film raw material according to item 1.

12. Wherein the dynamic friction coefficient between the core surface and the optical film raw material is 0.1 to 1.5.
3. The method for transporting a raw optical film described in 1. above.

13. A raw optical film, wherein a groove or a projection is formed inside a winding core for winding the raw optical film.

14. A method for preserving a raw optical film, comprising storing the raw optical film having a groove or a projection formed inside a core for winding the raw optical film.

15. A method for transporting a raw optical film, comprising transporting the raw optical film having a groove or a projection formed inside a core for winding the raw optical film.

16. An optical film raw material, wherein the surface resistivity of a core for winding the optical film raw material is 10 ¹² Ω / cm ² or less.

17. A method for preserving a raw optical film, comprising preserving the raw optical film having a surface resistivity of 10 ¹² Ω / cm ² or less on a core for winding the optical film raw material.

18. A method for transporting an optical film raw material, comprising transporting an optical film raw material having a surface resistivity of a winding core for winding the optical film raw material of 10 ¹² Ω / cm ² or less.

19. 1, 4, 7, 10 or 13, wherein the material of the surface of the core for winding the optical film raw material is a hard urethane resin and / or an epoxy resin.
The optical film raw material described in 1.

20. 2, 5, 8, 11, or 14, wherein the material of the surface of the core for winding the optical film raw material is a hard urethane resin and / or an epoxy resin.
The method for preserving an optical film raw material according to item 1.

21. 3, 6, 9, 12, or 15, wherein the material of the surface of the core for winding the optical film raw material is a hard urethane resin and / or an epoxy resin.
3. The method for transporting a raw optical film described in 1. above.

22. 20. The optical film raw material as described in 16 or 19 above, wherein the core for winding the optical film raw material contains at least one compound selected from graphite, carbon fiber and carbon black.

23. 21. The method for storing a raw optical film according to the above item 17 or 20, wherein the core for winding the raw optical film contains at least one compound selected from graphite, carbon fiber and carbon black.

24. 22. The method for transporting a raw optical film according to the above item 18 or 21, wherein the core for winding the raw optical film contains at least one compound selected from graphite, carbon fiber and carbon black.

25. The thickness of the raw optical film is 30 to 5
The above-mentioned 1, 4, 7, 10,
An optical film raw material according to 13, 16, 19 or 22.

26. The thickness of the raw optical film is 30 to 5
2, 5, 8, 11,
The method for preserving an optical film raw material according to 14, 17, 20 or 23.

27. The thickness of the raw optical film is 30 to 5
3, 6, 9, 12,
15. The method for transporting an optical film raw material according to 15, 18, 21 or 24.

28. The above-mentioned 1, 4, 7, wherein the optical film raw material is a cellulose ester film.
The optical film raw material according to 10, 13, 16, 19, 22 or 25.

29. 2, 5, 8, wherein the optical film raw material is a cellulose ester film
The method for preserving an optical film raw material according to 11, 14, 17, 20, 23 or 26.

30. The above 3, 6, 9, wherein the optical film raw material is a cellulose ester film.
The method for transporting a raw optical film according to 12, 15, 18, 21, 24 or 27.

31. 29. The optical film raw material as described in 28 above, wherein the cellulose ester is a lower fatty acid ester of cellulose.

32. 30. The method for preserving a raw optical film as described in 29 above, wherein the cellulose ester is a lower fatty acid ester of cellulose.

33. 31. The method for transporting a raw optical film according to the above item 30, wherein the cellulose ester is a lower fatty acid ester of cellulose.

Hereinafter, the present invention will be described in more detail. The center line peak height Rp of the present invention will be described.

The maximum peak height Rp is a kind of surface roughness parameter and can be obtained by a stylus type surface roughness meter. In the measurement of the stylus type surface roughness meter, the parameter value is slightly affected by the stylus diameter and the scanning speed used for the measurement. In the measurement of the surface shape of the present invention, a condition that the stylus diameter is about 1 μm and the scanning speed is 0.15 mm / sec is adopted.

The center line peak height Rp is obtained by extracting a portion of the reference length from the extracted curve, and determining the interval between the extracted curve center line and a straight line passing through the highest peak height in parallel with the extracted curve center line. , And the value is expressed in μm unit. In the present invention, the specification of the German standard DIN4762 is adopted.

In the present invention, the center line peak height Rp is 0.05 to 1.0 μm, preferably 0.1 to 0.8 μm, more preferably 0.3 to 0.6 μm. A smaller Rp is preferable because the core transfer is reduced, and a larger Rp is preferable because the coefficient of friction is reduced and wrinkles when starting to wind the film around the core are less likely to occur.

(Residual Good Solvent) The amount of the residual good solvent in the raw optical film is preferably 1% or less, more preferably 0.5% or less, and most preferably 0.2% or less. It is preferable that the amount of the residual good solvent is small because the core transfer can be reduced, and the center line peak height Rp is 0.05 to 1.0.
By combining with 0 μm, the core transfer can be further reduced. Since the amount of residual good solvent changes over time,
The amount of the residual good solvent specified in the present invention is defined as the amount of the residual good solvent in the film in the winder section where the film is wound around the core.

The amount of the residual good solvent can be measured by gas chromatography connected to a head space sampler. In the present invention, the measurement was performed under the following measurement conditions using a gas chromatography model 5890 SERISII manufactured by Hewlett-Packard Company and a headspace sampler HP7694 model.

Headspace sampler heating conditions: 120 ° C., 20 minutes GC introduction temperature: 150 ° C. Temperature rise: 40 ° C., 5 minutes hold → 100 ° C. (8 ° C./minute) Column: DB-WAX (J.W. 32mm,
(Length: 30 m) The good solvent and the poor solvent used in the present invention are defined as a good solvent that dissolves the cellulose ester used alone and a poor solvent that swells or does not dissolve alone. Therefore, a good solvent and a poor solvent change depending on the amount of bound acetic acid of the cellulose ester. For example, when acetone is used as a solvent, a good solvent is obtained when the amount of bound acetic acid of the cellulose ester is 55% and a poor solvent is obtained when the amount of bound acetic acid is 60%. turn into.

The good solvent used in the present invention includes organic halogen compounds such as methylene chloride and dioxolanes.

Depending on the amount of acetic acid bonded to the cellulose ester, examples of the solvent that can be a good solvent or a poor solvent include acetone, methyl acetate, and ethyl acetate.

As the poor solvent used in the present invention, for example, methanol, ethanol, n-butanol, cyclohexane and the like are preferably used.

Conventionally, the value was usually measured as a residual solvent amount by the following measuring method.

Residual solvent amount (%) = (mass before heat treatment−mass after heat treatment) / (mass after heat treatment) × 100 In the measurement of the amount of residual solvent, the heat treatment means that This means that heat treatment is performed at 1 ° C. for 1 hour.

The present inventor has found that the residual solvent amount obtained by this measuring method may not correlate well with the core transfer. However, the present inventor has found that the residual solvent amount obtained by this method includes moisture, and that there is a problem in obtaining the total amount of the solvent regardless of the type. That is, it is the amount of the good solvent contained in the film that significantly changes the physical properties of the film at the time of winding, and it has been found that controlling the amount improves the core transfer.

The amount of the residual solvent used in the present invention is a value measured by gas chromatography connected to a head space sampler.

(Coefficient of Dynamic Friction) In the present invention, the coefficient of dynamic friction between the core surface and the film is preferably 0.1 to 1.5, more preferably 0.3 to 1.0, and more preferably 0.5 to 1.0.
0.8 is more preferred. A lower dynamic friction coefficient is preferable because wrinkles are less likely to occur when the film is wound around the core, and a higher dynamic friction coefficient is preferable because the film is less likely to be displaced from the core during transport of the original film.

There are various methods for controlling the dynamic friction coefficient, and any method may be used. For example, there is a method of adding inorganic fine particles such as silica to the optical film, and a method of providing fine grooves on the circumference of the core surface.

The pitch of the fine grooves provided on the circumference of the core surface is preferably 0.1 to 3 mm, more preferably 0.3 to 1 mm. The width is preferably 0.1 to 1 mm, and 0.1 to 1 mm.
0.8 mm is more preferable, and 0.1 to 0.5 mm is most preferable.

The depth is preferably 1 to 20 μm, and 2 to 10 μm.
μm is more preferable, and 3 to 6 μm is most preferable. A longer pitch, a narrower width, and a shallower depth are preferred because of less transfer of the core, and a shorter pitch, a wider width, and a deeper depth are preferred because the effect of lowering the friction coefficient is greater. The groove may be concentric or spiral, but the spiral is preferable because it is excellent in workability when forming a core.

(Groove or convex portion of core) FIGS. 1 and 2 are schematic views showing an example of the shape of the core of the present invention.

1B, 2A, and 2B, a groove (3 spiral groove) as shown in FIG. 1B, FIG. 2A, and FIG. It is preferable that four convex portions (rounded) like the shape 4 are provided. It is preferable that a groove or a protrusion is provided inside the core, since the core is less likely to bend and a horse back failure is less likely to occur when the original film is stored.

FIG. 1A shows a winding core whose inside is not processed. (Shape 1) The width of the groove or the protrusion is preferably 5 to 30 mm, and 10 to 20 mm.
mm is more preferred. The depth and height are preferably 1 to 5 mm, more preferably 2 to 4 mm. This range has a great effect of making the core difficult to bend. Providing the groove is more preferable than providing the convex portion, because it can reduce the weight and can cope with the hollow core chucking method. The groove may be linear or spiral.

(Surface Resistivity) The surface resistivity of the core surface is 1
0 ¹² Ω / cm ² or less is preferable, 10 ¹⁰ Ω / cm ² is more preferable, and 10 ⁸ Ω / cm ² is most preferable. It is preferable that the lower the surface resistivity is, the less the dust is adsorbed and the less the core transfer due to the dust is. Surface resistivity of 10 ¹² Ω / cm ²
In order to achieve the following, antistatic treatment may be applied to the surface of the core. Specifically, it is performed by coating on the surface of an ion conductive substance or conductive fine particles, or by mixing it in a resin.

The ionic conductive substance shows electric conductivity,
It is a substance containing ions that are carriers that carry electricity, and examples thereof include ionic polymer compounds.

As the ionic polymer compound, Japanese Patent Publication No. Sho 4
9-23828, 49-23827, 47-2
Anionic polymer compounds as found in No. 8937;
JP-B-55-7334, JP-A-50-54672, JP-B-59-14735, JP-B-57-18175, and JP-A-57-18175.
Ionene-type polymers having a dissociating group in the main chain, such as those described in JP-A Nos. 7-18176 and 57-56059; Japanese Patent Publication Nos. 53-13223 and 57-15376.
No., JP-B No. 53-45231, and No. 55-145783
No. 55-65950, No. 55-67746, No. 57-11342, No. 57-19735, Japanese Patent Publication No. 5
8-56858, JP-A-61-27853, 62
And cationic pendant polymers having a cationic dissociating group in the side chain, such as those described in US Pat.

Examples of metal oxides include ZnO and TiO.
₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO,
BaO, MoO ₂ , V ₂ O _{5 and the} like, or a composite oxide thereof are preferable, and ZnO, TiO ₂ and SnO ₂ are particularly preferable. Examples of including heteroatoms include, for example, the addition of Al, In or the like to ZnO, and the addition of Nb or T to TiO ₂ .
The addition of a and the like, and the addition of Sb, Nb, a halogen element and the like are effective for SnO ₂ . The addition amount of these different atoms is preferably in the range of 0.01 mol% to 25 mol%, and particularly preferably in the range of 0.1 mol% to 15 mol%.

Examples of the conductive fine particles include conductive metal compounds and carbon black.

As carbon black, for example, Conductex 975 (specific surface area 250 m ² / g, particle size 24 mμ) manufactured by Columbia Carbon Co., Ltd., Conductex 9
00 (specific surface area 125 m ² / g, particle diameter 27 mμ), Conductex 40-220 (particle diameter 20 mμ), Conductex SC (particle diameter 20 mμ), Vulcan XC-72 manufactured by Cabot Corporation (specific surface area 254 m ² / g, Particle size 30m
μ), Vulcan P (particle diameter 20 mμ), Raven 104
0, 420, Black Pearls 2000 (particle size 15m)
μ) and conductive carbon black such as # 44 manufactured by Mitsubishi Kasei.

(Ultraviolet Absorber) An ideal ultraviolet absorber used for an optical film such as a cellulose ester film absorbs all the ultraviolet rays of less than 380 nm, and
Although there is no absorption of visible light having a wavelength of 370 nm or less, it is practically difficult. Therefore, in view of preventing the deterioration of the liquid crystal, it is excellent in absorbing the ultraviolet light having a wavelength of 370 nm or less and has a good liquid crystal display. From the viewpoint of properties, those having absorption of visible light having a wavelength of 400 nm or more as little as possible can be used. Practically, it is necessary to use an optical film having a transmittance at 380 nm of 8% or less from the viewpoint of good liquid crystal display properties.

Examples of commonly used ultraviolet absorbers include:
Examples include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylic acid ester-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel complex-based compounds, and the like.

As the benzotriazole-based ultraviolet absorber, a compound represented by the following formula (I) is preferably used.

[0073]

Embedded image

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and include a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group, and an alkoxy group. group, an acyloxy group, an aryloxy group, an alkylthio group, an arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- to 6-membered heterocyclic group, the carbon of R ₄ and R ₅ are 5- or 6-membered ring closure A ring may be formed.

Specific examples of the ultraviolet absorber preferably used in the present invention are shown below, but the present invention is not limited to these.

UV-1: 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-
ter-butylphenyl) benzotriazole UV-3: 2- (2'-hydroxy-3'-ter-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5 '-Ji-
ter-butylphenyl) -5-chlorobenzotriazole UV-5: 2- (2′-hydroxy-3 ′-(3 ″,
4 ", 5", 6 "-tetrahydrophthalimidomethyl)
-5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,
3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) A benzophenone-based ultraviolet absorber which is one of the ultraviolet absorbers used in the present invention is represented by the following general formula (I)
The compound represented by I) is preferably used.

[0077]

Embedded image

In the formula, Y represents a hydrogen atom, a halogen atom or an alkyl group, an alkenyl group, an alkoxy group and a phenyl group, and these alkyl group, alkenyl group and phenyl group may have a substituent. A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a -CO (NH) n-1-D group;
Represents an alkenyl group or a phenyl group which may have a substituent. m and n represent 1 or 2.

In the above, the alkyl group is, for example, a linear or branched aliphatic group having up to 24 carbon atoms, the alkoxy group is, for example, an alkoxy group having up to 18 carbon atoms, and the alkenyl group is, for example, carbon atom. Number 1
The alkenyl group up to 6 represents, for example, an allyl group, a 2-butenyl group and the like. Examples of the substituent to the alkyl group, alkenyl group and phenyl group include a halogen atom such as a chloro atom, a bromo atom and a fluorine atom, such as a hydroxy group, a phenyl group, and the like. May be used).

Specific examples of the benzophenone-based compound represented by the general formula (II) are shown below, but the present invention is not limited thereto.

UV-7: 2,4-dihydroxybenzophenone UV-8: 2,2′-dihydroxy-4-methoxybenzophenone UV-9: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-10: bis ( 2-methoxy-4-hydroxy-5
-Benzoylphenylmethane) The above-mentioned ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber having high transparency and an excellent effect of preventing deterioration of a polarizing plate or a liquid crystal element. A benzotriazole-based ultraviolet absorber which causes less unnecessary coloring is particularly preferable.

The amount of the ultraviolet absorber used in the present invention is not uniform depending on the kind of the compound and the conditions of use, but it is usually preferably from 0.2 g to 10.0 g per 1 m ² of the optical film, more preferably from 0.5 g to 5 g. 0.0 g is more preferable, and 0.8 g
g to 2.0 g are particularly preferred. Below this, the effect of absorbing ultraviolet light is small, and if it is too large, bleeding occurs and the film strength is also impaired.

In terms of the ratio to the resin, 0.5
% To 10%, more preferably 0.8% to 5%, particularly preferably 0.8% to 2.0%.

If the thickness of the cellulose ester film is too small, the strength of the polarizing plate as a protective film is insufficient.
The dimensional stability of the polarizing plate and the storage stability under wet heat deteriorate.
When the film thickness is large, the thickness of the polarizing plate becomes large, and it is difficult to reduce the thickness of the liquid crystal display. The film thickness of the cellulose ester film satisfying both requirements is 20 to 50 μm, preferably 30 to 50 μm.
５０50 μm, most preferably 40 μm.

As a method for adding the ultraviolet absorber, it may be added directly, but in-line addition, which is excellent in productivity, is preferred. In the in-line addition, a small amount of triacetyl cellulose is preferably added to and dissolved in an organic solvent (eg, methanol, methylene chloride, etc.) in advance, and then added to the dope composition using an in-line mixer.
The preferred amount of triacetyl cellulose is 1 to 10 parts by mass, more preferably 3 to 10 parts by mass, based on 100 parts by mass of the solvent.
5 parts by mass. When triacetyl cellulose is added, the viscosity of the ultraviolet absorbent-containing liquid increases, and it becomes easy to add a large amount in-line.

(Method of Manufacturing Polarizing Plate) The polarizing plate can be manufactured by a general method. For example, there is a method in which a cellulose ester film of the present invention is alkali-treated, and is immersed and stretched in an iodine solution, and bonded to both surfaces of a polarizing film using a completely saponified polyvinyl alcohol aqueous solution. The alkali saponification treatment refers to a treatment in which the cellulose ester film is immersed in a high-temperature strong alkaline solution in order to improve the wettability of the aqueous adhesive at this time and improve the adhesiveness.

(Method for Preserving Raw Material Film) It is preferable that the raw film material is stored in a state where the film is not in direct contact with the periphery while supporting a winding core as shown in FIG. If the raw film is placed directly, a portion of the film contacted by the load of the film will be damaged or deformed, which makes it difficult to use the film as an optical film.

It is preferable that the raw film is wrapped with a sheet of polyethylene or the like in order to prevent foreign matter from adhering.

The temperature environment for preserving the raw film is 5 to 4
0 ° C is preferable, and 15 to 25 ° C is more preferable. The humidity environment for storing the film is preferably 20 to 70% RH, more preferably 40 to 60% RH. When the temperature or humidity changes, the film shrinks or expands, so that the raw film wound around the core may be deformed. Therefore, it is preferable to store at a temperature and humidity close to the manufacturing conditions.

(Transportation Method of Film Source) The film source is transported by car or ship in a storage state as shown in FIG. The temperature and humidity at this time are preferably controlled in the same range as in the method for preserving the film raw material.

It is preferable that the film is transported while being stacked so that the width direction of the film material is perpendicular to the traveling direction of the transportation means. As a result, it is possible to prevent the film raw material from being displaced by the inertia force during transportation.

The cellulose ester film of the present invention will be described. As the cellulose ester, the cellulose ester is preferably a lower fatty acid ester.

The lower fatty acid in the lower fatty acid ester of cellulose ester means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate and the like are preferred examples of the lower fatty acid ester of cellulose. No.

In addition to the above, Japanese Patent Application Laid-Open No. H10-458
04, 08-231761, U.S. Pat. No. 2,31
Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in JP-A-9,052 and the like can be used.

Among the above descriptions, a particularly preferred lower fatty acid ester of cellulose is cellulose triacetate.

Further, from the viewpoint of base strength, it is particularly preferable to use a polymerization degree of 250 to 400 and an amount of bound acetic acid of 54 to 62.5%, and more preferably an amount of bound acetic acid of 58 to 62.5%.
62.5% cellulose triacetate.

As cellulose triacetate, either cellulose triacetate synthesized from cotton linter and cellulose triacetate synthesized from wood pulp can be used alone or in combination. If the releasability from the belt or drum becomes a problem, it is preferable to use a large amount of cellulose triacetate synthesized from cotton linter having good releasability from the belt or drum because the productivity is high. When a mixture of cellulose triacetate synthesized from wood pulp is used, the ratio of cellulose triacetate synthesized from cotton linter is 40% by mass or more,
It is preferable because the effect of releasability becomes remarkable, more preferably 60% by mass or more, and most preferably used alone.

The polarizing film, which is a main component of the polarizing plate used in the present invention, is an element that transmits only light of a plane of polarization in a certain direction, and a typical polarizing film currently known is a polyvinyl alcohol-based polarizing film. Polarizing films include polyvinyl alcohol-based films dyed with iodine and dichroic dyes. These are formed by forming a film of an aqueous polyvinyl alcohol solution and uniaxially stretching and dyeing the film, or dyeing the film and then uniaxially stretching the film, and then preferably performing a durability treatment with a boron compound.
A transparent plastic film, which is a protective film for a polarizing plate of the present invention, is laminated on the surface of the polarizing film to form a polarizing plate.

The method for producing the cellulose ester film of the present invention will be described. In the present invention, the dope solution in which the cellulose ester is dissolved refers to a state in which the cellulose ester is dissolved in a solvent (solvent), and a plasticizer is added to the dope solution. Additives can also be added. The concentration of the cellulose ester in the dope solution is preferably from 10 to 30% by mass, and more preferably from 18 to 20% by mass.

The solvents used in the present invention may be used alone or in combination. However, it is preferable to use a mixture of a good solvent and a poor solvent from the viewpoint of production efficiency. More preferably, a mixture of a good solvent and a poor solvent is used. The ratio is such that the good solvent is 70 to 95% by mass and the poor solvent is 5 to 30% by mass.

In preparing the above-mentioned dope solution, as a method for dissolving the cellulose ester, a general method can be used, but a preferable method is to mix the cellulose ester with a poor solvent and wet or swell. Let
Further, a method of mixing with a good solvent is preferably used. At this time, under pressure, the method of heating at a temperature not lower than the boiling point of the solvent at room temperature of the solvent and in a range where the solvent does not boil, and dissolving while stirring, in order to prevent the generation of massive undissolved substances called gels and mamako Is more preferable.

Pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

The heating temperature after the addition of the solvent is preferably set to a temperature not lower than the boiling point of the solvent used and not causing the solvent to boil, for example, preferably not lower than 60 ° C. and not lower than 70 to 110 ° C. . The pressure is adjusted at the set temperature so that the solvent does not boil.

After the dissolution, the resin is taken out of the container while cooling, or is taken out of the container by a pump or the like, cooled with a heat exchanger or the like, and supplied for film formation. The cooling temperature at this time may be cooled to room temperature, but it is more preferable to cool to a temperature 5 to 10 ° C. lower than the boiling point and perform casting at that temperature because the dope viscosity can be reduced.

In the casting step, a belt-shaped or drum-shaped stainless steel mirror-finished support is preferably used. The temperature of the support in the casting step can be cast in a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent, but casting on the support at 0 to 30 ° C. causes gelation of the dope. It is preferable because the separation time can be increased, and it is more preferable to cast on a support at 5 to 15 ° C. The peeling limit time is the limit of the casting speed at which a transparent and flat good film can be continuously obtained.
The time during which the cast dope remains on the support. It is preferable that the peeling limit time is short because the productivity is excellent.

The surface temperature of the support on the side to be cast (cast) is 10 to 55 ° C., the temperature of the solution is 25 to 60 ° C.
Further, the temperature of the solution is preferably higher than the temperature of the support by 0 ° C. or more, and more preferably 5 ° C. or more.

It is preferable that the temperature of the solution and the temperature of the support be as high as the drying speed of the solvent can be increased. However, if the temperature is too high, foaming or flatness may be deteriorated.

A more preferred range of the temperature of the support is 20
~ 40 ° C, a more preferred range of solution temperature is 35-45.
° C.

Further, the temperature of the support at the time of peeling is set to 10 to 4
The temperature is preferably set to 0 ° C, more preferably 15 to 30 ° C, because the adhesion between the film and the support can be reduced.

In order for the cellulose ester film at the time of production to exhibit good flatness, the amount of the residual good solvent when peeled from the support is preferably 5 to 60%, more preferably 10 to 40%. And particularly preferably 15 to 30
%.

In the drying step of the cellulose ester film, the film separated from the support is further dried, and the amount of the residual good solvent is preferably 1% or less.
The content is more preferably 0.5% or less, and most preferably 0.2% or less.

In the drying step of the cellulose ester film, the film peeled from the support is further dried so that the residual solvent content is preferably 3% by mass or less, more preferably 0.5% by mass or less. is there.

In the film drying step, a method of drying the film while transporting the film by a roll hanging method or a pin tenter method is generally employed. For liquid crystal display members, it is preferable to dry while maintaining the width by a pin tenter method in order to improve dimensional stability. In particular, it is particularly preferable to maintain the width at a place where the amount of the residual solvent is large immediately after peeling off from the support, since the effect of improving the dimensional stability is further exhibited. The means for drying the film is not particularly limited, and is generally performed using hot air, infrared rays, a heating roll, a microwave, or the like.
It is preferable to use hot air in terms of simplicity. Drying temperature is 40
It is preferable that the temperature is gradually increased in three to five steps in the range of 150 to 150 ° C., and it is more preferable to perform in the range of 80 to 140 ° C. in order to improve dimensional stability.

The cellulose ester film of the present invention preferably contains a plasticizer. There is no particular limitation on the plasticizer that can be used, but in the case of phosphate esters, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. In the phthalate ester system, diethyl phthalate,
In the glycolic acid ester system such as dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate,
It is preferable to use methylphthalylethyl glycolate, butylphthalylbutyl glycolate or the like alone or in combination.

The inclusion of these plasticizers is particularly preferable because a film having excellent dimensional stability and water resistance can be obtained.

In the present invention, the use of the above-mentioned ultraviolet absorber and a plasticizer having a melting point of 20 ° C. or less among these plasticizers is excellent in workability and is preferable in terms of foreign matter failure and surface quality. The plasticizer having a melting point of 20 ° C. or lower is not particularly limited as long as it has a melting point of 20 ° C. or lower, and can be selected from the above plasticizers.

For example, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, triacetin, ethyl phthalyl ethyl glycolate and the like can be mentioned. it can. It is also preferable to use these plasticizers alone or in combination.

The melting point in the present invention refers to the true melting point described in the Dictionary of Chemistry published by Kyoritsu Shuppan Co., Ltd.

The amount of these plasticizers to be used is 1 to 1 with respect to cellulose ester in terms of film performance, processability and the like.
15% by mass is preferred. For a liquid crystal display member, the content is more preferably 5 to 15% by mass, particularly preferably 7 to 12% by mass, from the viewpoint of dimensional stability.

The melting point of cellulose ester is 2
The content of the plasticizer at 0 ° C. or lower is preferably 1% by mass to 10% by mass, and more preferably 3% by mass to 7% by mass.

The workability refers to the ease with which a base film or a liquid crystal display member is processed by slitting or punching. If the workability is poor, the cut surface becomes saw-toothed and chips are generated. This is not preferable because it adheres to the surface and causes a foreign matter failure.

The cellulose ester film of the present invention comprises
It is preferably used for a liquid crystal display member because of its high dimensional stability and good ultraviolet ray cutting performance. The liquid crystal display member is a member used for a liquid crystal display device, and includes, for example, a polarizing plate, a protective film for a polarizing plate, a retardation plate, a reflector, a viewing angle improving film, an antiglare film, a non-reflective film, and charging. Prevention films and the like. Among the above descriptions, the cellulose ester film of the present invention is more preferably used in a polarizing plate and a protective film for a polarizing plate, which have strict requirements for dimensional stability.

If necessary, fine particles may be added to the optical film of the present invention as a matting agent. Examples of the fine particles used in the present invention include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, Mention may be made of aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferred in that turbidity is reduced, and silicon dioxide is particularly preferred.

The fine particles of silicon dioxide are, for example, Aerosil R972, R972V, R974, R8
12, 200, 200V, 300, R202, OX5
0 and TT600 (all manufactured by Nippon Aerosil Co., Ltd.), and these can be used.
The fine particles of zirconium oxide are, for example, commercially available under the trade names of Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.), and these can be used.

Examples of the polymer include a silicone resin, a fluorine resin and an acrylic resin. Among them, silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable.
03, 105, 108, 120, 145, 3
120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.), and these can be used.

Of these, Aerosil 200V and Aerosil R972V are particularly preferable because they have a large effect of lowering the coefficient of friction while keeping the turbidity of the optical film low.

[0127]

EXAMPLES The present invention will now be described specifically with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 <Samples 1 to 21> (Preparation of Core) A core A was prepared in the shape shown in FIG. 1 (b). As the core material of the core, the inner diameter is 152 mm and the outer diameter is 165.
A coating layer of hard urethane resin mixed with carbon black was applied to the outermost layer using an FRP core having a length of 1450 mm and a thickness of 3 mm. This coating layer has a polished surface and an Rp of 0.
It processed so that it might be set to 4 micrometers.

The cores B to G and K to K were the same as the core A except that the cores B to G and K to M were changed to the conditions described in Table 1.
M was produced. The core H has a pitch of 0.1 mm on the surface of the core.
It was produced in the same manner as the winding core A except that a fine groove of 5 mm, a width of 0.3 mm and a depth of 5 mm was spirally provided. Core I,
J was produced in the same manner as in the core A except that the amount of carbon black mixed in the outermost layer was reduced and the surface resistivity was controlled.

(Silicon Oxide Dispersion) Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) (Average primary particle diameter: 12 nm, apparent specific gravity: 100 g / l) 10 parts by mass Ethanol 90 parts by mass The above components were stirred and mixed with a dissolver for 30 minutes. Thereafter, dispersion was performed with Menton-Gaulin. The liquid turbidity after dispersion is 93 pp
m.

(Preparation of Additive Solution A) 2- (2-hydroxy-3-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole 10 parts by mass Triacetyl cellulose synthesized from linter cotton 4 parts by mass More than 100 parts by mass of methylene chloride was charged into a closed vessel, heated, stirred, completely dissolved, and filtered.

To the mixture, 10 parts by mass of a silicon oxide dispersion was added with stirring, and the mixture was further stirred for 30 minutes.

(Preparation of Dope A) 85 parts by weight of triacetyl cellulose synthesized from linter cotton 15 parts by weight of triacetyl cellulose synthesized from wood pulp 2 parts by weight of ethyl phthalyl ethyl glycolate 8.5 parts by weight of triphenyl phosphate Part: 475 parts by weight of methylene chloride 50 parts by weight of ethanol The above was put into a closed vessel, and completely dissolved and filtered while heating and stirring to prepare a dope solution A.

The additive solution was added to 100 parts by mass of the dope solution in an amount shown in Table 1, and the mixture was sufficiently mixed with an in-line mixer (Toray static in-tube mixer Hi-Mixer, SWJ) and filtered. Next, using a belt casting device, the mixture was uniformly cast on a stainless steel band support at a temperature of 33 ° C. and a width of 1700 mm. The solvent was evaporated on the stainless steel band support until the residual good solvent amount became 20%, and the peeling tension was 127.
Peeled from the stainless steel band support at N / m. 1500 mm of peeled cellulose triacetate film
After drying, the drying zone was conveyed by a number of rolls to finish the drying. The slit was slit to a width of 1330 mm and the initial winding tension was 220 N under the conditions shown in Table 2.
/ M and a taper of 40%, and the film was wound around a core to obtain a cellulose triacetate film sample 1. At this time, the residual good solvent amount of the cellulose triacetate film was 0.15.
%Met.

Samples 2 to 19 were prepared in the same manner except that the conditions of Sample 1 were changed as shown in Table 2. Sample 20 was prepared in the same manner except that the length of the drying zone of Sample 1 was reduced to half. At this time, the residual good solvent amount of the cellulose triacetate film was 0.42%. Sample 21 was prepared in the same manner except that the length of the drying zone of Sample 1 was reduced to 1/3.
Was prepared. At this time, the residual good solvent amount of the cellulose triacetate film was 0.81%.

The bonding method will be described with reference to FIG. FIG.
(A) is a film-sided double-sided tape (width 20 mm, glue thickness 4)
0 μm, length 20 cm) is adhered to the raw film at two places in the width of the winding core (two places at the end embossed part), and the raw film at the end of the winding core is R-shaped (the center of the raw film) (Adhesion method A) FIG. 3B shows a double-sided tape with a film surface (width 2).
(0 mm, glue thickness 40 μm) is placed 5 cm on the core. Adhere so as to cover the embossing on one side of the film. The raw film is cut diagonally. The oblique cut angle θ is 2
0 to 60 ° (adhesion method B).

FIG. 3C shows a double-sided tape having a film surface (width of 20 m).
m, glue thickness 40 μm) is applied to the entire surface in the width direction of the core and adheres to the original film (adhesion method C).

(Evaluation Method) (Rp) Measurement was performed with a surface roughness measuring machine SV-402 (manufactured by Mitutoyo Corporation) in accordance with German Standard DIN4762.

(Residual Good Solvent) The measurement was carried out under the following measurement conditions using a gas chromatography type 5890 SERISII and a head space sampler HP7694 type manufactured by Hewlett-Packard Company.

Headspace Sampler Heating Condition: 12
0 ° C, 20 minutes GC introduction temperature: 150 ° C Temperature rise: 40 ° C, hold for 5 minutes → 100 ° C (8 ° C / min) Column: DB-WAX manufactured by J & W (inner diameter 0.32 mm,
Length 30 m) The amount of the good solvent methylene chloride in this example was measured as the amount of the remaining good solvent.

(Coefficient of Dynamic Friction) The coefficient of dynamic friction between the film and the core was measured according to JIS-K-7125 (1987). Prepare a plate-shaped sample with the same material and the same surface processing as the core, place the cut film sample on it,
Place a further 200 g of weight, and the sample moving speed is 10
The weight was horizontally pulled under the conditions of 0 mm / min and a contact area of 80 mm × 200 mm, the average load (F) during the movement of the weight was measured, and the dynamic friction coefficient (μm) was obtained from the following equation.

Coefficient of kinetic friction = F (gf) / weight of weight (gf) (back failure of horse, transfer of winding core)
Wrap and store at 25 ° C, 50
% For 30 days. Thereafter, the sample was taken out of the box, the polyethylene sheet was opened, and a fluorescent lamp tube lit on the surface of the raw film sample was reflected and reflected. The distortion or fine disturbance was observed, and the horse's back failure was classified into the following levels.

A: Fluorescent lamp looks straight B: Fluorescent lamp looks partially bent C: Fluorescent lamp appears to be spotted The length at which the core transfer at the C level shown below occurred was measured. The shorter the length at which the core transfer occurs, the better.

C: Point-like deformation of 50 μm or more or band-like deformation in the width direction is clearly visible (wrinkles at the beginning of winding) The work of winding the raw film around the winding core is performed, and wrinkles occur at the beginning of winding. In the case of failure, the raw film was removed from the core and the work of rewinding was performed. The number of failures at this time was counted. This work 1
The measurement was performed 0 times, an average value was obtained, and the results were ranked according to the following levels.

A: 0 or more and less than 1 time B: 1 or more and less than 3 times C: 3 or more and less than 5 times D: 5 or more times

[0146]

[Table 1]

[0147]

[Table 2]

[0148]

As demonstrated in the examples, the optical film raw material according to the present invention and the method of storing and transporting the same can reduce the transfer of the core, hardly cause wrinkles at the beginning of winding, and retain the horse back even after long-term storage. It has an excellent productivity that does not cause failure.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a shape of a winding core of the present invention.

FIG. 2 is a schematic view showing an example of a shape of a winding core of the present invention.

FIG. 3 is a schematic view showing one example of a bonding method for bonding a core and a film raw material of the present invention.

FIG. 4 is a cross-sectional view showing one example of a method for storing a raw film film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Concave groove 3 Spiral groove 4 Convex part 5 Raw film 6 Double-sided tape on film surface 7 Support plate 8 Storage box

Claims (33)

[Claims] 1. An optical film raw material, wherein a center line peak height Rp of a surface of a core for winding the optical film raw material is 0.05 to 1.0 μm. 2. The preservation of an optical film raw material, wherein a center line peak height Rp of the surface of a core for winding the optical film raw material is 0.05 to 1.0 μm. Method. 3. The transport of the optical film raw material, wherein the optical film raw material having a center line peak height Rp of 0.05 to 1.0 μm on the surface of the core for winding the optical film raw material is transported. Method. 4. The optical film raw material according to claim 1, wherein the residual good solvent amount of the optical film raw material is 1% or less. 5. The method for preserving a raw optical film according to claim 2, wherein the amount of the residual good solvent in the raw optical film is 1% or less. 6. The method for transporting a raw optical film according to claim 3, wherein the residual good solvent amount of the raw optical film is 1% or less. 7. The optical film raw material according to claim 4, wherein the residual good solvent is methylene chloride. 8. The method according to claim 5, wherein the residual good solvent is methylene chloride. 9. The method for transporting a raw optical film according to claim 6, wherein the residual good solvent is methylene chloride. 10. A dynamic friction coefficient between a core surface and a raw optical film is 0.1 to 1.5.
The optical film raw material described in 1. 11. The dynamic friction coefficient between the surface of the core and the raw optical film is 0.1 to 1.5.
The method for preserving an optical film raw material according to item 1. 12. The optical film according to claim 3, wherein a dynamic friction coefficient between the core surface and the raw optical film is 0.1 to 1.5.
3. The method for transporting a raw optical film described in 1. above. 13. An optical film raw material, wherein a groove or a convex portion is formed inside a core for winding the optical film raw material. 14. A method for preserving a raw optical film, wherein the raw optical film having a groove or a projection formed inside a core for winding the raw optical film is stored. 15. A method for transporting an optical film raw material, comprising transporting an optical film raw material having a groove or a projection formed inside a core for winding the optical film raw material. 16. An optical film raw material, wherein the surface resistivity of a core for winding the optical film raw material is 10 ¹² Ω / cm ² or less. 17. A method for preserving a raw optical film, wherein the raw optical film having a surface resistivity of 10 ¹² Ω / cm ² or less of a core for winding the raw optical film is stored. 18. A method for transporting a raw optical film, comprising transporting the raw optical film having a surface resistivity of 10 ¹² Ω / cm ² or less of a core for winding the raw optical film. 19. The material of the surface of the core for winding the optical film raw material is a hard urethane resin and / or an epoxy resin.
The optical film raw material described in 1. 20. The material of the surface of the core for winding the optical film raw material is a hard urethane resin and / or an epoxy resin.
The method for preserving an optical film raw material according to item 1. 21. The material of the surface of the core for winding up the optical film raw material is a hard urethane resin and / or an epoxy resin.
3. The method for transporting a raw optical film described in 1. above. 22. The raw optical film according to claim 16, wherein the core for winding the raw optical film contains at least one compound selected from graphite, carbon fiber and carbon black. . 23. The optical film raw material according to claim 17, wherein the core for winding the optical film raw material contains at least one compound selected from graphite, carbon fiber and carbon black. How to save. 24. The raw optical film according to claim 18, wherein the core for winding the raw optical film contains at least one compound selected from graphite, carbon fiber and carbon black. Transportation method. 25. The film thickness of the raw optical film is 30 to 50.
Claim 1, 4, 7, 10,
An optical film raw material according to 13, 16, 19 or 22. 26. The film thickness of the raw optical film is 30 to 50.
μm.
The method for preserving an optical film raw material according to 14, 17, 20 or 23. 27. The film thickness of the raw optical film is 30 to 50.
3, 6, 9, 12,
15. The method for transporting an optical film raw material according to 15, 18, 21 or 24. 28. The method according to claim 1, wherein the raw optical film is a cellulose ester film.
The optical film raw material according to 10, 13, 16, 19, 22 or 25. 29. The method according to claim 2, wherein the raw optical film is a cellulose ester film.
The method for preserving an optical film raw material according to 11, 14, 17, 20, 23 or 26. 30. The optical film raw material is a cellulose ester film, wherein the original optical film is a cellulose ester film.
The method for transporting a raw optical film according to 12, 15, 18, 21, 24 or 27. 31. The raw optical film according to claim 28, wherein the cellulose ester is a lower fatty acid ester of cellulose. 32. The method according to claim 29, wherein the cellulose ester is a lower fatty acid ester of cellulose. 33. The method according to claim 30, wherein the cellulose ester is a lower fatty acid ester of cellulose.