JP2002194106A - Cellulose ester film, polarized light plate protecting film and method for preparing cellulose ester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose ester film having excellent handling properties in accordance with tendency of making a liquid crystal display device into a thin film, also in the case of making a polarized light plate protecting film into a thin film, also in the case of a process for making a thin film, and in the case of a process of making the polarized plate. SOLUTION: The cellulose ester film which is characterized by containing 0.04 to 0.3% by mass of microparticulates based on the cellulose ester film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cellulose ester film, and more particularly to a film suitable as a protective film for a polarizing plate of a liquid crystal display.

[0002]

2. Description of the Related Art In recent years, as a liquid crystal display (LCD) is used in various places, it is required to be thinner and lighter, and a polarizing plate used in the LCD is also required to be thinner and lighter. Have been.

At present, a cellulose triacetate (TAC) film is mainly used as a protective film for a polarizing plate used in LCDs, but its thickness is relatively thick, 80 μm or more. Since four protective films are usually used as LCD members, it is urgently desired to make them thinner.

However, TAC, which is the aforementioned protective film,
As the film is made thinner, wrinkles may occur during the production of the TAC film and during the subsequent polarizing plate production process, for example, during the transport process during film formation, and the flatness of the film in the wound state may deteriorate. However, it was not easy to make the film thinner.

[0005] In addition, when the liquid crystal display device is assembled with a reduction in thickness, display unevenness is likely to occur. As a result of intensive studies, the present inventors have found that the display unevenness is caused by blocking such as sticking of films, and have reached the present invention. As the film becomes thinner, blocking becomes more likely to occur, and the blocking causes uneven coating, wrinkles, and the like, resulting in non-uniformity on the surface. The surface uniformity is a characteristic that is particularly required in a film for a liquid crystal display device, which is particularly severe, more than a film for other uses. The present invention has been made in order to improve the present invention.

[0006]

[Problems to be Solved by the Invention] Even when a protective film for a polarizing plate is made thinner as a liquid crystal display element becomes thinner, cellulose having excellent handleability in a film forming process and a polarizing plate making process is obtained. The present invention relates to an ester film and a method for producing the same.

[0007]

[Means for Solving the Problems] 1. a cellulose ester film, wherein the film contains fine particles in an amount of 0.04 to 0.3% by mass based on the cellulose ester; 2. a cellulose ester film, which contains fine particles having an average particle size of 1.0 to 10.0 μm in the film; In a cellulose ester film containing fine particles in a film, in a region from the surface of the cellulose ester film to a depth of 10 μm, the fine particles have a cross section perpendicular to the film of 5 to 500 particles / 1000 μm.
^2. A cellulose ester film characterized by being present. 4. In a cellulose ester film containing fine particles in a film, in a region from the surface of the cellulose ester film to a depth of 10 μm, the fine particles have a cross section perpendicular to the film of 5 to 500 particles / 1000 μm.
^3. The cellulose ester film according to claim 1, wherein ^{2 is} present. 5. A cellulose ester film, wherein the haze of the film is 0 to 0.6%, and the coefficient of dynamic friction between the front and back of the film is 0.5 to 1.3. 6. In a cellulose ester film containing fine particles in a film, the number of fine particles in a section perpendicular to the cellulose ester film in a region from the surface of the cellulose ester film to 10% of the film thickness from the surface of the cellulose ester film to 100 μm ^2, and the remaining 80 % Of fine particles in a cross section perpendicular to the cellulose ester film in the region of
6. The cellulose ester film according to claim 3, wherein the ratio A / B of 100 μm ² is 1 or more. 7. The cellulose ester film has a thickness of 20 to 6
The cellulose ester film according to any one of claims 1 to 6, wherein the thickness is 5 µm. 8. The cellulose ester film according to any one of claims 1, 2, 3, 4, 6, and 7, wherein the true specific gravity of the fine particles is 0.8 to 4.0. 9. 9. The cellulose ester film according to claim 1, wherein the fine particles are made of a compound containing a silicon atom. 10. 10. The projections having a height of 0.1 μm or more from the surface of the cellulose ester film and having a height of 0.1 μm or more are 10 to 500 protrusions / 100 μm ² , according to any one of claims 1 to 9, wherein Cellulose ester film. 11. Knurling is applied to both ends in the width direction of the cellulose ester film, and the knurling height
Ratio X of (a: μm) to film thickness (d: μm)
The cellulose ester film according to any one of claims 1 to 10, wherein, when (%) = (a / d) x 100, X is in the range of 0 to 25%. 12. A protective film for a polarizing plate, comprising the cellulose ester film according to any one of claims 1 to 11. 13. Fine particles are dispersed in a high-pressure dispersing apparatus at 100 kgf / cm ²
After the dispersion treatment under the above pressure conditions, a cellulose ester is mixed with a dope dissolved in a solvent, the mixed solution is cast on a support, and the cellulose ester film is dried and formed into a film. Production method. 14． Fine particles, lower alcohols 25% by mass to 10%
A cellulose ester film characterized by being dispersed in a solvent containing 0% by mass, then mixing a cellulose ester with a dope dissolved in the solvent, casting the mixture on a support, drying and forming a film. Manufacturing method. 15. Fine particles are dispersed in a solvent at a concentration of 1% by mass to 30% by mass, and then mixed with a dope in which a cellulose ester is dissolved in a solvent. The mixed solution is cast on a support, dried, and formed into a film. A method for producing a cellulose ester film, comprising: 16. The thickness of the cellulose ester film is 20 to
The method for producing a cellulose ester film according to any one of claims 13 to 15, wherein the thickness is 65 µm.

Hereinafter, the present invention will be described specifically. Examples of the cellulose ester according to the present invention include cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, and cellulose acetate propionate. In the case of cellulose triacetate, cellulose triacetate having a degree of polymerization of 250 to 400 and an amount of bound acetic acid of 54 to 62.5% is particularly preferable, and a base strength of 58 to 62.5% of bound acetic acid is more preferable. As the cellulose triacetate, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination.

It is preferable to use a large amount of cellulose triacetate synthesized from a cotton linter having good releasability from a belt or a drum because the productivity efficiency is high. The ratio of cellulose triacetate synthesized from cotton linter is 60
When the amount is at least 70% by mass, the effect of the releasability becomes remarkable, so the amount is preferably at least 60% by mass, more preferably at least 85% by mass, and most preferably used alone.

The plasticizer which can be used in the present invention is not particularly limited, but in the case of a phosphate ester, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate Phthalic acid ester, such as tributyl phosphate, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc .; Rate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, etc. Preferably used in combination is.

If necessary, two or more plasticizers may be used in combination. In this case, the use ratio of the phosphate ester plasticizer of 50% or less causes hydrolysis of the cellulose ester film. It is preferable because it is difficult to obtain and has excellent durability.

It is more preferred that the ratio of the phosphate plasticizer is small, and it is particularly preferable to use only the phthalate or glycolate plasticizer.

In the present invention, in order to further control the water absorption and the water content within specific ranges, the amount of the plasticizer is preferably 3% by mass with respect to the cellulose ester.
% By mass to 30% by mass, more preferably 10% by mass.
To 25% by mass, more preferably 15% to 25% by mass
It is. If the content is more than 30% by mass, mechanical strength and dimensional stability deteriorate.

In the cellulose ester film of the present invention, it is preferable to use an ultraviolet absorber. The ultraviolet absorber is excellent in absorbing the ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal, 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 small as possible are preferably used.

In the present invention, in particular, the wavelength is 370 nm.
Should be 10% or less, preferably 5% or less, more preferably 2% or less.

Examples of commonly used compounds include, but are not limited to, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, and the like.

In the present invention, one of these ultraviolet absorbers
It is preferable to use at least two kinds of UV absorbers, and two or more different UV absorbers may be contained.

The ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber. An embodiment in which a benzotriazole-based ultraviolet absorber with less unnecessary coloring is added to the cellulose ester film is particularly preferable.

The method of adding the ultraviolet absorber may be such that the ultraviolet absorber is dissolved in an organic solvent such as alcohol, methylene chloride or dioxolane and then added to the dope, or added directly to the dope composition. Those that do not dissolve in an organic solvent, such as inorganic powder, are dispersed in an organic solvent and a cellulose ester using a dissolver or a sand mill, and then added to the dope.

The amount of the ultraviolet absorber used in the present invention is 0.1% by mass to 2.2% by mass based on the cellulose ester.
5% by mass, preferably 0.5% to 2.0% by mass,
More preferably, it is 0.8% by mass to 2.0% by mass. If the amount of the ultraviolet absorber is more than 2.5% by mass, the transparency tends to deteriorate, which is not preferable.

Examples of the solvent for the cellulose ester according to the present invention include lower alcohols such as methanol, ethanol, n-propyl alcohol, iso-propyl alcohol and n-butanol; lower aliphatic alcohols such as cyclohexanedioxane and methylene chloride. Hydrocarbon chlorides and the like can be used.

The solvent ratio is, for example, 70 to 95% by mass of methylene chloride, and the other solvent is 5 to 30% by mass.
Is preferred. The cellulose ester concentration is 10 to 50.
% By mass is preferred. The heating temperature after the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and not boiling the solvent, and is preferably set to, for example, 60 ° C. or higher and 80 to 110 ° C. The pressure is determined so that the solvent does not boil at the set temperature.

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 method for producing the cellulose ester film in the present invention is not particularly limited,
Methods generally used in the art may be used, for example, U.S. Pat. Nos. 2,492,978, 2,739,070, 2,739,069, 2,492,977, and 2,336. No. 3,310, No. 2,367,603, No. 2,607,704, British Patent Nos. 64,071, 7
35,892, JP-B-45-9074, 49-4
No. 554, No. 49-5614, No. 60-27562
Nos. 61-39890 and 62-4208 can be referred to.

In addition to the cellulose ester and the solvent, necessary additives such as a plasticizer and an ultraviolet absorber may be mixed with the solvent in advance, dissolved or dispersed, and then added to the solvent before dissolving the cellulose ester. It may be added to the dope after dissolution.

There is no particular limitation on the type of the pressurized container, and it is only necessary to be able to withstand a predetermined pressure and to perform heating and stirring under pressure. For the pressurized container, other instruments such as a pressure gauge and a thermometer are appropriately arranged.

The 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 carried out from the outside. For example, a jacket type is preferred because temperature control is easy.

The heating temperature after the addition of the solvent is preferably in the range of not less than the boiling point of the solvent used and not boiling the solvent, and is preferably set in the range of not less than 60 ° C. and 80 to 110 ° C., for example. . The pressure is determined so that the solvent does not boil at the set temperature.

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 and cooled with a heat exchanger or the like, and is provided for film formation. However, it is more preferable to cool to a temperature lower than the boiling point by 5 to 10 ° C. and perform casting at that temperature because the viscosity of the dope can be reduced.

In the present invention, a dope obtained by dissolving a cellulose ester is cast on a support (casting step), and then heated to remove a part of the solvent (drying step on the support). The film is peeled from the support, and the peeled film is dried (film drying step) to obtain a cellulose ester film.

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

In the drying step on the support, the dope is cast, gelled once, and the time from casting to peeling is 10 minutes.
Assuming 0%, dope temperature within 4% within 30% of casting.
By setting the temperature to 0 ° C. to 70 ° C., the evaporation of the solvent is promoted, the film can be peeled off from the support more quickly, and the peeling strength is further increased.
It is more preferable that the temperature be 5 ° C to 70 ° C. This temperature is 2
It is preferably maintained at 0% or more, more preferably at least 40%.

The drying on the support is carried out at a residual solvent content of 60% to 1%.
Peeling from the support at 50% is preferable because the peel strength from the support is reduced, and 80 to 120% is more preferable. The temperature of the dope when peeling is 0 ° C to 30 ° C
Can increase the base strength at the time of peeling,
It is preferable to prevent the base from breaking at the time of peeling.
20 ° C. is more preferred.

The amount of residual solvent in the film is represented by the following equation. Residual solvent amount = mass of residual volatiles / mass of film after heat treatment × 100% The residual mass of volatiles is obtained by subtracting the film mass after heat treatment from the film mass before heat treatment when the film is heat-treated at 115 ° C. for 1 hour. Value.

In the film drying step, the film peeled from the support is further dried to reduce the residual solvent amount to 3% by mass.
Or less, preferably 1% by mass or less, more preferably 0.5% by mass or less.
It is preferable that the content is not more than mass% in order to obtain a film having good dimensional stability. In the film drying step, a method of drying while transporting a film by a roll suspension method, a pin tenter method, or a clip tenter method is generally employed. For a liquid crystal display member, it is preferable to dry while maintaining the width by a tenter method in order to improve dimensional stability. In particular, when the width is kept in a large amount of the residual solvent immediately after being peeled off from the support, the effect of improving the dimensional stability is further exhibited.In particular, in the drying step after peeling from the support, the film is evaporated by the evaporation of the solvent. Tries to shrink in the width direction.

The higher the temperature, the greater the shrinkage.
Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the resulting film. From this point, for example, a method of drying all the steps or a part of the steps as described in JP-A-62-46625 while drying both ends of the web with a clip in the width direction / tenter method Is preferred.

The means for drying the film is not particularly limited, and is generally performed by hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to use hot air in terms of simplicity. The drying temperature is preferably divided into three to five stages in a temperature range of 40 ° C. to 150 ° C. and gradually increased.
It is more preferable to carry out in the range of ° C. in order to improve dimensional stability.

The steps from casting to post-drying may be performed in an air atmosphere or in an atmosphere of an inert gas such as nitrogen gas.

It goes without saying that the drying atmosphere is carried out in consideration of the explosive limit concentration of the solvent.

The winding machine relating to the production of the cellulose ester film of the present invention may be a generally used one, such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress. It can be wound by a winding method.

The thickness of the cellulose ester film according to the present invention is generally 20 to 200 μm. However, the thickness and the weight of the polarizing plate used in the LCD are required to be 20 to 200 μm. It is preferably 65 μm, more preferably 30 to 60 μm, and still more preferably 35 to 60 μm.
50 μm. If the thickness is more than this, the rigidity of the film is reduced, so that problems such as wrinkles are likely to occur in the polarizing plate making process. Few.

Further, fine particles are added as a matting agent to the cellulose ester film according to the present invention.

The type of the fine particles may be either an inorganic compound or an organic compound. Examples of the inorganic compound include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide and the like. Among these, a compound containing a silicon atom is preferable, and fine particles of silicon dioxide are particularly preferable. Examples of the silicon dioxide fine particles include AEROSIL manufactured by Aerosil Co., Ltd.
200, 200V, 300, R972, R972V, R
974, R202, R812, R805, OX50, T
T600 and the like.

Examples of the organic compound include acrylic resin,
Silicone resin, fluorine compound resin, urethane resin and the like can be mentioned.

In the present invention, the primary particle size of the fine particles is not particularly limited, but the average particle size in the final film must be 1.0 to 10.0 μm. Preferably,
1.0 to 8.0 μm, more preferably 2.0 to 5.0
μm.

The average particle size of the fine particles refers to the average value of the length in the major axis direction of the particles at the observation position of the film when the cellulose ester film is observed with an electron microscope or an optical microscope. As long as the particles are observed in the film, they may be primary particles or secondary particles in which the primary particles are aggregated, but most of the particles usually observed are secondary particles.

As an example of the measuring method, for example, a portion having an area of 9775 μm ² per one film is observed with a microscope, and the average value of the particle diameter of the fine particles at the observation place is obtained. In the same film, the same measurement is performed at random at 10 points, and an average value is obtained. further,
The value obtained by averaging the average values of the 10 locations was defined as the average particle size.

In the case of fine particles, the primary particle size, the particle size after being dispersed in a solvent, and the particle size added to the film often change, and it is important that the fine particles eventually become cellulose ester in the film. The purpose is to control the particle size formed by agglomeration and aggregation. When the particle size exceeds 10 μm, deterioration of haze or the like may be observed, or a failure as a foreign matter in a wound state may occur. Also, 1.0
When the thickness is less than μm, a sufficient effect of improving the winding property is not seen, and particularly, the cellulose ester film has a thickness of 20 to 65 mm.
This is remarkable in the case of μm.

In the present invention, the true specific gravity of the fine particles is 0.8
Must be ~ 4.0. Preferably 0.8 to 3.
0, more preferably 0.85 to 2.5. The true specific gravity as used herein means the ratio of mass to volume theoretically calculated from the elements constituting the substance. When the true specific gravity is 0.8 or less, in the state of the dispersion of the fine particles, the buoyancy of the fine particles is large, separation occurs, and the distribution of the fine particles in the film becomes uneven. When the true specific gravity is 4.0 or more, The fine particles settle out in the state of the fine particle dispersion, and a portion where the fine particles are not added is generated in the film, so that it is necessary to be within the range of the present invention.

In the present invention, in the region from the surface of the cellulose ester film to a depth of 10 μm, the fine particles having an average particle size of 1.0 to 10.0 μm have a cross section perpendicular to the cellulose ester film of 5 to 500 particles / particle. 100
0 μm ^{2 is} present. Preferably, 5-300 pieces / 1
Is 000μm ^2, more preferably from 10 to 250 pieces / 1000 .mu.m ^2. If the number is five or less, the film surface roughness becomes too smooth, and blocking occurs due to an increase in the coefficient of friction. In the case of 500 or more, the coefficient of friction of the film surface is too low, and a winding shift occurs during winding, or the film has low transparency and haze is high, so that the film has no value as a liquid crystal display device film. The scope of the present invention is essential.

The number of fine particles in the region from the surface of the cellulose ester film to a depth of 10 μm can be measured, for example, as follows. For each film, ten tomographic photographs were taken at random, and for each tomographic photograph, 1000 μm ² at a position from the surface up to 10 μm.
Measure the number inside. Then, an average value of ten points is calculated.

In the present invention, the fine particles are used in an amount of 0.04 to 0.3% by mass relative to the cellulose ester. Preferably, it is 0.05 to 0.2% by mass, more preferably 0.05 to 0.15% by mass. 0.04
In the following, blocking occurs due to an increase in the coefficient of friction because the film surface roughness is too smooth. If it is 0.3 or more, the coefficient of friction of the film surface is too low, and a winding deviation occurs at the time of winding, or the transparency of the film is low and the haze is high. Range is mandatory.

In the present invention, the cellulose ester fiber
In the area from the surface of the film to 10% of the film thickness
Number of fine particles in a section perpendicular to the film A / 100
μm ^TwoAnd perpendicular to the film in the remaining 80% area
Number of fine particles in a complex cross section / 100 μm^TwoNumber ratio A /
B is 1 or more, preferably 1 to 100, more preferably
Or 1.1 to 100.

A / 100 μm ² is 0.5 to 50 100 μm ² , preferably 0.5 to 40 100 μm ^2.
μm ² . In addition, the B number / 100 μm ² is 0 to 2
5/100 μm ² , more preferably 0 to 5/100 μm ² . It is preferable to reduce the number of fine particles inside the film that hardly contributes to the prevention of blocking, because haze of the entire film can be reduced while maintaining blocking properties.

[0055] The height projections or 0.1μm is from the film surface on the surface of the cellulose ester film is 10 to 500 pieces / 100 [mu] m ^2, preferably 10 to 400 pieces / 100 [mu] m ^2, more preferably Is 15-300 / 100 μm ² .

The term "fold wrinkle" in the present invention refers to a wrinkle generated when the film breaks from both ends during film transport during film production or winding.

In the present invention, the term "protruding press failure" refers to floating when air that has entered between the films at the time of winding during film production does not escape or foreign matter enters and occurs. .

The term “winding deviation” in the present invention refers to a phenomenon in which the film is wound right and left due to meandering of the film during winding during film production, or the film protrudes from the end surface during storage or transport after winding. It is preferable that the protrusion amount is within 5 mm.

In the present invention, a composition in which fine particles and a solvent are mixed is treated with a high-pressure dispersion device. The high-pressure dispersing apparatus used in the present invention is an apparatus that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed through a thin tube at a high speed. By treating with a high-pressure dispersion device, for example, it is preferable that the maximum pressure condition inside the device is 100 kgf / cm ² or more in a thin tube having a diameter of 1 to 2000 μm.

More preferably, it is at least 200 kgf / cm ² . At this time, the maximum arrival speed is 100 m / sec.
Those that reach the above, and those whose heat transfer speed reaches 100 kcal / hr or more are preferable.

The above high pressure disperser <
There is an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by offluidics Corporation or a nanomizer manufactured by Nanomizer. Other examples include a Manton-Gaulin type high-pressure dispersing apparatus such as a homogenizer manufactured by Izumi Food Machinery.

In the present invention, the fine particles are dispersed in a solvent containing 25% by mass to 100% by mass of a lower alcohol, and then mixed with a dope in which a cellulose ester is dissolved in the solvent. A cellulose ester film is cast, dried and formed into a film. As the content ratio of the lower alcohol, preferably,
50 mass% to 100 mass%, more preferably 75 to 1 mass%
00% by mass. The lower alcohols preferably include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like.

The solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used in forming a cellulose ester film.

In the present invention, the fine particles are dispersed in the solvent at a concentration of 1% by mass to 30% by mass. If the dispersion is performed at a concentration higher than this, the viscosity rapidly increases, which is not preferable. The concentration of the fine particles in the dispersion is preferably 5 to 25% by mass, and more preferably 10 to 20% by mass.

In the present invention, the haze of the film can be measured, for example, according to ASTM-D1003-52.

In the present invention, the haze is preferably 0 to 0.6%, more preferably 0 to 0.4%, and further preferably 0.1 to 0.2%.

In the present invention, the dynamic friction coefficient of the front and back of the film can be measured, for example, by a method specified in JIS-K-7125 (1987).

In the present invention, when a standard substance used for measuring the dynamic friction coefficient of a general film is used as a mating material (for example, a metal such as a hard sphere), fine particles are applied to the front and back of the film as in the present invention. The effect of the addition cannot be confirmed. It is necessary to measure the coefficient of dynamic friction between films. Therefore, in accordance with JIS-K-7125, a film is used for both the test piece and the mating material, and
It can be measured by arranging the film so that the front and back surfaces are in contact.

In the present invention, the dynamic friction coefficient is 0.5 to
1.3, more preferably 0.5 to
1.0, and more preferably 0.6 to 0.8.

In the present invention, a so-called knurling process is carried out to give irregularities to both ends in the width direction of the cellulose ester film to make the ends bulky.

When the ratio of the knurling height (a: μm) to the film thickness (d: μm) X (%) = (a / d) × 100, X = 0 to 25%. Features. Preferably 1 to 15%, more preferably 1 to 1
0%. If the knurling height ratio is larger than this range, the winding shape is likely to be deformed, and if the knurling ratio is small, the winding property is undesirably deteriorated.

In the present invention, it is preferable that the amount of foreign matter in the cellulose ester film is small. In particular, it is preferable that the number of foreign substances recognized in the polarization crossed Nicols state is small.

The foreign substance recognized in the polarization crossed Nicols state refers to a substance measured by placing two polarizing plates in a perpendicular (crossed Nicols) state and placing a cellulose ester film between them. In a polarization crossed Nicol state, such foreign matter is observed only in the place of the foreign matter in the dark field, so that its size and number can be easily identified.

Regarding the number of foreign substances, the size perceived in the polarization crossed Nicols state per area of 250 mm ² is 5 to 5.
It is preferable that the number of foreign substances having a size of 50 μm is 200 or less and the number of foreign substances having a size of 50 μm or more is substantially zero. More preferably, 5-
The number of foreign substances having a size of 50 μm is 100 or less, more preferably 50 or less.

The above-mentioned cellulose ester film with few foreign substances can be obtained by any method without particular limitation, but can be achieved by filtering a dope composition obtained by dissolving a cellulose ester in a solvent using the following filter paper. In this case, as the type of filter paper, it is preferable to use a filter paper having a drainage time of 20 sec or more and to filter at a filtration pressure of 16 kg / cm ² or less to form a film. More preferably, 30 sec
The filtration is performed using a filter paper of c or more and a filtration pressure of 12 kg / cm ² or less, more preferably a filter paper of 40 sec or more and a filtration pressure of 10 kg / cm ² or less. It is more preferable to use two or more of the filter papers. Further, the filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

The method for producing the polarizing plate according to the present invention is not particularly limited, and it can be produced by a general method. For example, there is a method in which a cellulose triester film 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. Instead of the alkali treatment, a method for increasing the adhesion as described in JP-A-6-94915 and JP-A-6-118232 may be used.

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, and a non-reflective film. Films, antistatic films and the like.

Among them, it is more preferable to apply the present invention to a polarizing plate, a protective film for a polarizing plate, a retardation plate, and a viewing angle improving film, which are strictly required for dimensional stability.

[0079]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 <Preparation of Sample 1> (Preparation of Dispersion A) Ethanol 27 parts by mass Fine particle I / silicon dioxide fine particles 3 parts by mass (trade name: Aerosil 200V, primary particle size: 12 nm; manufactured by Nippon Aerosil Co., Ltd.) After mixing the above and stirring at 500 rpm for 30 minutes,
250kgf / c with a Menton-Gaulin type high pressure disperser
Dispersion was performed at a pressure of m ² to form a dispersion. (Preparation of Additive Solution A) Dispersion A 22 parts by mass Cellulose triacetate synthesized from cotton linter 12 parts by mass 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole (ultraviolet ray) Absorbent I) 26 parts by mass Methylene chloride 290 parts by mass For the above-mentioned additive solution, a centrifugal particle size distribution analyzer (CAPA)
500, manufactured by Horiba Ltd.), the average particle size was 1.2 μm. (Dope composition A) Cellulose triacetate synthesized from cotton linter (degree of acetylation 61.0%) 85 parts by mass Cellulose triacetate synthesized from wood pulp (degree of acetylation 61.0%) 15 parts by mass ethylphthalylethyl Glycolate (plasticizer A) 2 parts by mass Triphenyl phosphate (plasticizer B) 8 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass Dope composition A is charged into a sealed container, heated to 70 ° C., and stirred. , Cellulose triacetate (TAC)
Was completely dissolved to obtain a dope. The time required for dissolution was 4 hours. After filtering the dope composition A, the addition ratio of fine particles to cellulose triacetate was 0.05
After mixing the dope composition A and the additive liquid A so as to obtain a mass%, the mixture is uniformly cast on a stainless steel band support at a dope temperature of 35 ° C. and 30 ° C. using a belt casting apparatus. Was. After drying to a range where the peeling was possible, the dope was peeled off from the stainless steel band support.
At this time, the residual solvent amount of the dope was 25%. The time required from dope casting to peeling was 3 minutes. After peeling from the stainless steel band support, drying is completed in a drying zone of 50 ° C., 90 ° C., 120 ° C., and 130 ° C. while being transported by a number of rolls, and a width of 10 m is applied to both ends of the film.
m, knurling with a height of 4 μm and a film thickness of 40 μm
m of cellulose triacetate film sample 1 was prepared. The film width is 1300mm and the winding length is 3000
m. The winding tension is 20 kg / 130 initial tension.
0 mm and a final winding tension of 10 kg / 1300 mm. (Preparation of Samples 2 to 10) Film Samples 2 to 10 were prepared in the same manner as in the preparation of Sample 1, except that the thickness of the cellulose triacetate film and the amount of added fine particles were changed as shown in Table 1.

[0080]

[Table 1]

Film sample 1 prepared as described above
The following performance evaluations were performed for the samples No. to No. 10. (Evaluation method) 1. Average particle size Observation of the particles with a scanning electron microscope (3000 times magnification)
The diameter of the circle circumscribing the particles was defined as the particle size. And change the place appropriately, measure 10 pieces at 10 places at random,
Give the average value for each. Further, the average value of the average values at the ten locations was defined as the average particle size. 2. Haze: Measured according to ASTM-D1003-52. 3. Dynamic friction coefficient: The dynamic friction coefficient between the film surface and the back surface is determined according to JIS-K-7125 (1987) so that the film is cut out so that the front and back surfaces of the film are in contact with each other, a 200 g weight is placed, the sample movement speed is 100 mm / min, and the contact area is 8
The weight was horizontally pulled under the condition of 0 mm × 200 mm, the average load (F) during which the weight was moving was measured, and the dynamic friction coefficient (μ) was obtained from the following equation.

Dynamic friction coefficient = F (gf) / weight of weight (gf) Protrusive push failure: A film wound 1500 m in the manufacturing process was removed at 23 ° C. and 55% RH in an atmosphere.
After being stored for a month, the film was cut out by 1 m in the length direction, and the number of occurrences of convex deformation was evaluated. If it is 3 pieces / m ² or less, there is no practical problem. 5. Winding deviation: The deviation width at the end of the wound sample was measured. It is preferably 10 mm or less. 6. Number of fine particles: 10 tomographic photographs were taken at random on the film, and each tomographic photograph was 10 μm from the surface.
The number in 1000 μm ² at the location within was counted, and the average value at 10 locations was calculated. 7. Fold wrinkles: The number of wrinkles generated in 100 m of the film was visually observed and counted. 8. Fine particle distribution A / B: A tomographic photograph of 10 places of the cellulose ester film was taken, and the number in 100 μm ² in the region from the surface to 10% of the film thickness was counted as A and the remaining 80% in the region. The number in 100 μm ² was counted as B, and the ratio A / B was calculated. 9. Number of protrusions on the film surface: The number of protrusions having a height of 0.1 μm or more from the film surface was counted on the surface of the cellulose ester film using an optical interference type surface roughness meter WYKO.

As can be seen from Table 1, according to the method of the present invention, the failure at the time of winding was improved by adding fine particles to the cellulose ester film. In particular, when the cellulose ester film is thinned, the effect is remarkably observed. (Example 2) In the same manner as in Sample 2, as shown in Table 2, except that the dispersion pressure of the Manton-Gaulin type high-pressure disperser and the fine particles were changed to the following types under the preparation conditions of Sample 2 of Example 1. 18 were prepared and evaluated. Fine particles II / fine particles of silicon dioxide (trade name: Aerosil R972V, primary particle size: 16 nm; manufactured by Nippon Aerosil Co., Ltd.) Fine particles III / fine particles of silicon dioxide (trade name: Aerosil TT600, primary particle size: 40 nm; Nippon Aerosil ( Fine Particles IV / Silicone Resin Fine Particles (trade name: Tospearl 105, Primary Particle Size: 0.5 μm; Toshiba Silicone Co., Ltd.) Fine Particles V / PMMA Fine Particles (trade name: MX-15
0, primary particle size: 1.5 μ; manufactured by Soken Chemical Co., Ltd.) Fine particles ■ / Silicone resin fine particles (trade name: KMP60
5, primary particle diameter: 2.0μ; manufactured by Koshi Chemical Industry Co., Ltd.)

[0084]

[Table 2]

As can be seen from Table 2, according to the method of the present invention, failure during winding was improved by adding fine particles to the cellulose ester film. (Example 3) Except for changing the height of the knurling as shown in Table 3 under the conditions for preparing Sample 2 of Example 1,
Similarly, as shown in Table 3, samples 19 to 23 were prepared and evaluated.

[0086]

[Table 3]

As can be seen from Table 3, in the present invention, the knurling height ratio is more preferably 0 to 25%. (Example 4) Under the conditions for preparing sample 2 of Example 1, in a solvent in which the mixing ratio (parts by mass /% by mass) of ethanol and methylene chloride was changed as shown in Table 4 when preparing the fine particle dispersion A. Table 4 was prepared in the same manner except that the fine particles were dispersed.
Samples 24 to 28 were prepared as shown in FIG.

In the preparation of the sample 2 of the first embodiment,
At the time of preparing the dispersion liquid A, as shown in Table 4, the dispersion was performed while changing the concentration of the fine particles. At this time, samples 29 to 32 were prepared as shown in Table 4 by changing the amount of the dispersion added to the additive so that the amount of the fine particles added to the cellulose triacetate was the same as that of the sample 2 of Example 1. did.

The same evaluation as in Example 1 was performed on Samples 24 to 32.

[0090]

[Table 4]

As can be seen from Table 4, when a dispersion liquid of fine particles is prepared, the failure at the time of winding is improved within the scope of the present invention.

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[Procedure amendment]

[Submission date] January 25, 2001 (2001.1.2)
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0083

[Correction method] Change

[Correction contents]

As can be seen from Table 1, according to the method of the present invention, the failure at the time of winding was improved by adding fine particles to the cellulose ester film. In particular, when the cellulose ester film is thinned, the effect is remarkable. (Example 2) In the same manner as in Sample 2, as shown in Table 2, except that the dispersion pressure of the Manton-Gaulin type high-pressure disperser and the fine particles were changed to the following types under the preparation conditions of Sample 2 of Example 1. To 18 were prepared and evaluated. Fine particles II / fine particles of silicon dioxide (trade name: Aerosil R972V, primary particle size: 16 nm; manufactured by Nippon Aerosil Co., Ltd.) Fine particles III / fine particles of silicon dioxide (trade name: Aerosil TT600, primary particle size: 40 nm; Nippon Aerosil ( Fine Particles IV / Silicone Resin Fine Particles (trade name: Tospearl 105, Primary Particle Size: 0.5 μm; Toshiba Silicone Co., Ltd.) Fine Particles V / PMMA Fine Particles (trade name: MX-15
0, primary particle size: 1.5 μ; manufactured by Soken Chemical Co., Ltd.) Fine particles VI / silicone resin fine particles (trade name: KMP6)
05,1 Tsugitsubukei: 2.0μ; manufactured by Shin-Etsu Chemical Industry Co., Ltd.)

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 008

[Correction method] Change

[Correction contents]

[0086]

[Table 3]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 1:00 B29K 1:00 B29L 7:00 B29L 7:00 (72) Inventor Koichi Saito Hino-shi, Tokyo In-house (72) Inventor Yuko Yokouchi, 1st Sakuramachi Konica Stock Association In-house (72) Inventor Noriaki Tachibana 1st Sakuracho, Hino-shi, Tokyo In-house Konica Stock Exchange F-term ( (Reference) 2H091 FA08X FA08Z FB02 FB13 LA02 LA11 LA30 4F071 AA09 AB18 AB26 AF30 AH19 BA02 BB02 BC01 BC10 BC12 BC14 BC16 4F205 AA01 AB11 AC05 AG01 AH42 GA07 GB02 GC07 GE21 GF02 GF24 GN22 4J002 DG002 PG 012 002

Claims (16)

[Claims] 1. A cellulose ester film characterized in that the film contains fine particles in an amount of 0.04 to 0.3% by mass based on the cellulose ester. 2. A film having an average particle size of 1.0 to 10.
A cellulose ester film containing fine particles of 0 μm. 3. In a cellulose ester film containing fine particles in a film, the fine particles have a cross section perpendicular to the film in a region from the surface of the cellulose ester film up to a depth of 10 μm in a range of 5 to 500 particles / 1.
A cellulose ester film characterized by being present at 000 μm ² . 4. In a cellulose ester film containing fine particles in a film, the fine particles have a cross section perpendicular to the film in a region from the surface of the cellulose ester film to a depth of 10 μm in a range of 5 to 500 particles / 1.
3. The cellulose ester film according to claim 1, wherein said cellulose ester film is present in an amount of 000 μm ² . 5. The film has a haze of 0 to 0.6% and a coefficient of dynamic friction on the front and back of the film of 0.5 to 1.
3. A cellulose ester film, 6. In a cellulose ester film containing fine particles in a film, the number A of fine particles / 100 μm in a cross section perpendicular to the cellulose ester film in a region from the surface of the cellulose ester film to 10% of the film thickness. 6. The cellulose according to claim 3 or 5, wherein the ratio A / B of the number of fine particles / 100 μm ^{2 in} the cross section perpendicular to the cellulose ester film in the region of ² and the remaining 80% is 1 or more. Ester film. 7. The cellulose ester film according to claim 1, wherein said cellulose ester film has a thickness of 20 to 65 μm. 8. The true specific gravity of the fine particles is 0.8 to 4.0.
The cellulose ester film according to any one of claims 1, 2, 3, 4, 6, and 7. 9. The method according to claim 1, wherein the fine particles are made of a compound containing a silicon atom.
The cellulose ester film according to any one of 6, 7, and 8. 10. The method according to claim 1, wherein the number of projections having a height of 0.1 μm or more from the surface of the cellulose ester film is 10 to 500/100 μm ² . The cellulose ester film according to any one of the above. 11. A knurling process is applied to both ends in the width direction of the cellulose ester film, and a ratio of knurling height (a: μm) to film thickness (d: μm) X (%) = (a / D) × 100, X = 0 to
11. The method according to claim 1, wherein the range is 25%.
The cellulose ester film according to any one of the above. 12. A protective film for a polarizing plate, comprising the cellulose ester film according to any one of claims 1 to 11. 13. A method for dispersing 100 kg of fine particles in a high-pressure dispersion device
After performing dispersion treatment under a pressure condition of f / cm ² or more, a cellulose ester is mixed with a dope dissolved in a solvent, the mixed solution is cast on a support, and dried to form a film. A method for producing a cellulose ester film. 14. The fine particles are dispersed in a solvent containing 25% by mass to 100% by mass of a lower alcohol, mixed with a dope in which a cellulose ester is dissolved in the solvent, and the mixture is cast on a support. And producing the cellulose ester film by drying. 15. The fine particles are dispersed in a solvent at a concentration of 1% by mass to 30% by mass, and then mixed with a dope in which a cellulose ester is dissolved in a solvent. The mixed solution is cast on a support and dried. And producing a cellulose ester film. 16. The cellulose ester film according to claim 13, wherein said cellulose ester film has a thickness of 20 to 65 μm.
16. The method for producing a cellulose ester film according to any one of items 15 to 15.