JP2000098133A - Optical retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit easy and large-scale production of a soft thin film having a large area by adding a specified amt. of a mixture of specified nonionic fluoroalkyl-alkoxylate surfactants to a polymerizable mesogen compsn. SOLUTION: Prior to the production process or during the production process, a mixture of nonionic fluoroalkyl-alkoxylate surfactants selected from formula I and formula II is added by 50 to 2500 ppm to a polymerizable mesogen compsn. In the formulae, n is an integer 4 to 12, x is an integer 5 to 15. As for the substrate, a PET or TAC film is used. In the production process, the polymerizable mesogen compsn. is applied on the substrate. Or, prior to the production process, the surface of the PET or TAC film in contact with the polymerizable mesogen compsn. is rubbed in one direction, or coated with a polyimide layer rubbed in one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical retardation film having an anisotropic polymer material layer having an optical axis substantially parallel to a layer plane, a method for producing the same, and a method for producing such an optical retardation film. It relates to the use in liquid crystal displays, and to liquid crystal cells and liquid crystal display devices provided with such an optical retardation film.

[0002]

2. Description of the Related Art Optical retardation films are used for light modulation in various optical applications. For example, a quarter wavelength retardation film (QWF) can transform circularly polarized light into linearly polarized light. Furthermore, the optical retardation film can be used as a compensation film,
The optical properties of a liquid crystal display, such as contrast ratio and halftone, can be improved over a wide viewing angle range. Certain applications require birefringent optical films that have an extraordinary optical axis that is parallel to the film plane, and such films are also known as A-plates. For use as A-plates, preformed isotropic or liquid crystal polymer uniaxially stretched films have been suggested in the prior art. WO97 / 03
676 describes an optical retardation film comprising an anisotropic polymer material layer having an optical axis with a small tilt angle with respect to the layer plane, which comprises applying a polymerizable mesogen mixture onto a substrate, And then curing the mixture.

However, when manufacturing such an optical retardation film, an anisotropic film having a small tilt angle between the film plane and the optical axis, for example, having a tilt angle close to zero or substantially zero, is used. Obtaining a planar orientation of a tropic polymer material is often difficult. Thus, it can be used to improve the optical properties of liquid crystal displays, can be easily produced on a large scale as a flexible thin film having a large area, and is also substantially parallel to the film plane. It remains desirable to be able to utilize an A-plate optical retardation film that has a certain optical axis with a substantially zero tilt angle.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical retardation film free from the above-mentioned disadvantages. Another object of the present invention is to provide a method for producing such an optical retardation film.

[0005]

SUMMARY OF THE INVENTION It has been found that these problems are overcome by providing an optical retardation film according to the present invention. Thus, one of the objects of the present invention is to have an optical axis substantially parallel to the layer plane,
A) a polymerizable mesogenic composition having an anisotropic polymer material layer and comprising the following components, which may be dissolved in an organic solvent at a concentration of up to 50% by weight: Or 10 to 50% by weight of two polymerizable mesogen compounds represented by the following formula Ia and one or two polymerizable mesogen compounds 5 to 35 represented by the following formula Ib:
weight%:

[0006]

Embedded image (In each formula, W is H or CH ₃ , and n is 3 to
And R is an alkyl or alkoxy group having 1 to 8 carbon atoms); b) a polymerizable mesogenic compound 15 of the formula II
~ 60% by weight:

[0007]

Embedded image (Wherein W is H or CH ₃ , and n is 3-6
And Z ¹ and Z ² are each independently —COO— or —OCO—, and X ¹
And X ² are each independently H or CH ₃ ) and c) 0.1-8% by weight of a photoinitiator;

B) aligning the polymerizable mesogen composition in a homogeneous orientation; c) polymerizing the polymerizable mesogen composition by exposure to ultraviolet light; and d) optionally, Removing from the polymerized material, wherein the optical retardation film is obtained by a method comprising: i) prior to or during step a), the following formulas III and IV:

Embedded image (In each formula, n is an integer of 4 to 12, and x is
A mixture of nonionic fluoroalkyl-alkoxylate surfactants selected from the group consisting of from 5 to 15) is added to the polymerizable mesogenic composition in an amount of 50 to 2500 ppm;

Ii) A PET or TAC film is used as a substrate, and the polymerizable mesogen composition is applied on the substrate in step a) of the above method, and iii) prior to step a) of the above method Rubbing the surface of the PET or TAC film adjacent to the polymerizable mesogen composition in a single direction, or covering the surface with a unidirectionally rubbed polyimide layer. An object of the present invention is to provide the obtained optical retardation film. Another object of the present invention is to provide a method for producing such an optical retardation film. Other objects of the present invention will be immediately apparent to those skilled in the art from the following detailed description. An optical retardation film comprising an anisotropic polymer material layer having an optical axis substantially parallel to the layer plane according to the present invention is obtained by a method comprising the above steps a) to d).

The present invention relates to the following preferred embodiments: * Plane and optical axis of the anisotropic polymer material layer
Optical retardation, wherein the tilt angle between
* Nonionic fluoroalkyl-alkoxylate
The mixture of surfactants comprises at least two compounds of formula III
50 to 2500 ppm of the compound represented, preferably
Is contained in an amount of 800 to 1200 ppm.
Optical retardation film obtained from the above-mentioned nonionic fluoroalkyl-alkoxylate
The mixture of surfactants is represented by at least two formulas IV.
50 to 2500 ppm, preferably
According to the above method, which is contained in an amount of 800 to 1800 ppm.
Optical retardation film obtained; * in a compound represented by formula II, X¹Is H
Yes, X²Is CH₃ And Z¹Is -COO-
And then Z²Is -OCO-, according to the above method.
The resulting optical retardation film;

* The polymerizable mesogenic composition is one or two of the following formula V:

Embedded image (W, n and R have the meanings given for formula I) in an amount of from 5 to 55% by weight, preferably from 15 to 45% by weight. * In the formulas Ia, Ib, II and V, W is H, and the optical retardation film obtained by the above method; * In step a) of the above method, PET is used as the substrate.
Using a film, and prior to step a), this PE
An optical retardation film obtained by the above method, wherein the surface of the T film adjacent to the polymerizable mesogen composition is rubbed in a single direction;

It is another object of the present invention to provide a method for producing an optical retardation film comprising an anisotropic polymer material layer having an optical axis substantially parallel to the layer plane, the method comprising: Includes the steps a) to d) described in the present specification. Yet another object of the present invention is to use the optical retardation film described herein for a liquid crystal display. Still another object of the present invention is a liquid crystal display device including the optical retardation film and the liquid crystal cell described in the present specification. The retardation of the optical retardation film according to the invention is preferably in the range from 20 to 600 nm. A film exhibiting a retardation of 25 to 170 nm, more preferably a film having a retardation of 300 to 600 nm is particularly preferred.

The optical retardation film according to the present invention comprises:
Electro-optical displays including active matrix type and passive matrix type, especially TN
Type (twisted nematic), STN type (super twisted nematic), ECB type (electrically controlled birefringence), OCB type (optically compensated birefringence), DAP type (deformation effect of alignment phase) ), CSH type (color super homeotropic VAN / VAC (vertically aligned nematic / cholesteric)), OMI type (optical mode interference), or SBE type (super birefringence effect)
And also guest-host, I
It is suitable for use as a phase retarder or as a compensation film for PS (in-plane switching), ferroelectric or antiferroelectric displays.

As an example, the optical retardation film according to the present invention can be used as a QWF together with a broadband reflection type polarizing plate. In this case, the retardation of the optical retardation film is substantially a reflection type polarizing plate. Is 1/4 times the center wavelength of the wavelength range reflected by. The optical retardation film according to the invention contains a layer of polymerized mesogenic material, characterized by having a considerably large birefringence. Furthermore, the optical properties of the optical retardation film, such as birefringence, can be controlled by changing the type and ratio of the polymerizable mesogen compound in the polymerizable material. The optical retardation film according to the present invention has an anisotropic polymer layer having a major optical axis substantially parallel to the plane of the layer. The tilt angle between the plane of the layer and the optical axis of the layer is preferably in the range of 0-1 °, especially 0-0.5 °, particularly preferably 0-0.3 °. A tilt angle of approximately 0 degrees is particularly preferred.

As described throughout this specification,
The tilt angle of the optical retardation film of the present invention should be understood to be a tilt angle over the entire film,
The values are the averages of the various regions of the film. The tilt angle thus defined is the tilt angle of the outer surface of the film, ie, the surface that is exposed to the atmosphere, and / or the inner surface of the film, ie, adjacent to the substrate on which the film is formed. It need not be the same as the other surface. The optical retardation film according to the present invention is obtained by applying a polymerizable mesogen composition in the form of a film on a substrate, orienting the material, and then polymerizing the oriented material. As the substrate, a PET (polyethylene terephthalate) or TAC (triacetylcellulose) film can be used. It is particularly preferable to use a PET film as the substrate. PET films are available, for example, from ICI Corp. Is marketed under the registered trade name of Melinex. TAC film is, for example, Lonz
a Commercially available from AG (Switzerland) or Fuji Photo (Japan).

In the method according to the present invention, the planar orientation of the coating layer of the polymerizable mesogenic composition having a small tilt angle with respect to the plane of the layer, that is, the mesogen molecules in the composition are substantially aligned with the plane of the layer. The orientation parallel to is, inter alia,-using a PET or TAC substrate,-adding a surfactant to the polymerizable mesogenic composition,-rubbing the surface of the substrate or, alternatively,
This is achieved by covering the substrate with a polyimide layer and rubbing the polyimide layer before applying the polymerizable composition on the substrate. The surfactant used in the process according to the invention is a mixture of nonionic fluoroalkylalkoxylate surfactants selected from formulas III and IV below:

[0017]

Embedded image In each formula, n is an integer from 4 to 12, and x is 5
It is an integer of １５15. By using these surfactants, polymerized thin films having very small tilt angles can be produced. The surfactant of formula III is commercially available under the registered trade name Fluorad 171 (from 3M Co.) and the surfactant of formula IV is the registered trade name of Zonyl FSN. (Du Pont).

The amount of surfactant is preferably between 500 and 2
It is 500 ppm, in particular 1000 to 2500 ppm, very preferably 1500 to 2500 ppm. In addition to the above means for achieving a small tilt angle, the nature of this orientation also depends on the rubbing angle, ie the angle between the main rubbing direction and the respective main optical axis of the substrate or polyimide layer. The rubbing is preferably performed in a single direction substantially parallel to the main optical axis of the substrate. As an example, rubbing may be performed using a rubbing cloth, or by a flat bar coated with a rubbing cloth, or by a rubbing roller, for example a rapid spinning roller brushing on a substrate, or one or both of the rollers may be a rubbing cloth. This can be achieved by placing the substrate between two rollers, which may be covered. Rubbing can also be accomplished by winding the substrate at least partially around a roller covered with a rubbing cloth at a fixed angle.

As rubbing cloth, all materials known to those skilled in the art for this purpose can be used. For example, a commercially available standard velvet can be used as the rubbing cloth. After rubbing, the ability of the substrate to induce the orientation of the polymerizable mesogen composition applied on the substrate also depends on the operating parameters of the rubbing operation, such as rubbing pressure and rubbing speed, and using rubbing rollers. In this case, it depends on the rotation speed of the roller, the shape of the rubbing roller and the tension on the substrate. In a preferred embodiment, the rubbing length involved in the rubbing operation according to the above method is preferably 0.
2-5 meters, especially 0.5-3 meters, most preferably 1.0-2.5 meters. The polymerizable mesogenic composition is performed by exposing the composition to ultraviolet light in the presence of an ultraviolet absorbing photoinitiator that decomposes under ultraviolet radiation to generate free radicals that initiate the polymerization reaction. It is cured by photopolymerization.

The polymerization can be carried out in air or in an inert gas atmosphere, for example in a nitrogen atmosphere. For curing in air, for example, the commercially available photoinitiator Irgacure 906 can be used, while for curing in a nitrogen atmosphere, for example, commercially available Irgacure 651 or 184 (all Ciba Geigy AG Which are commercially available from The amount of photoinitiator in the polymerizable mesogen composition is from 0,1 based on the weight of the total mixture.
It is between 1 and 8%, preferably between 0.5 and 6%, very preferably between 1 and 5%. The polymerizable mesogenic composition is preferably
Before coating on a substrate, it is dissolved in an organic solvent. Suitable solvents include organic solvents such as methyl ethyl ketone, toluene, cyclohexanone or cyclopentane, which are preferably used with an auxiliary solvent such as xylene or isopropyl alcohol, or two or more of these solvents. Mixtures can also be used.

In order to obtain a polymer film having good orientation, the polymerization must be performed in the liquid crystal phase of the polymerizable mesogen composition. Preferably, the curing temperature is at least 40 ° C. below the clearing temperature of the polymerizable mesogenic composition. A particularly preferred curing temperature is 30 to 60C. It is preferred to use high or medium pressure ultraviolet light, preferably 250 nm to 420 nm, especially 320 n.
An irradiation wavelength of m to 390 nm is used. As the actinic radiation source, for example, one ultraviolet lamp or a set of ultraviolet lamps can be used. The use of a high power lamp can reduce the curing time. The radiation generated by the lamp used in the present invention is preferably 0.01 to 100 mW.
/ Cm ² , particularly preferably 10 to 50 mW / cm ²
It is. The curing time according to the invention is preferably not longer than 1 minute, particularly preferably shorter than 30 seconds, very preferably shorter than 5 seconds.

The thickness of the optical retardation film according to the present invention obtained by the above method is preferably 0.5 to 0.5.
30 μm, especially 0.5-20 μm, most preferably 0.1 μm.
5 to 15 μm. The polymerizable mesogenic composition used in the production of the optical retardation film according to the invention comprises the following polymerizable mesogenic compounds: a) one or two polymerizable mesogenic compounds of the formula Ia 10 to 50% by weight and one or two of the polymerizable mesogen compounds of the formula Ib
35% by weight:

[0023]

Embedded image In each formula, W is H or CH ₃ , and n is 3-6
And R is alkyl or alkoxy having 1 to 8 carbon atoms; b) one of the polymerizable mesogenic compounds of formula II
5 to 60% by weight:

[0024]

Embedded image Wherein W is H or CH ₃ , n is an integer of 3-6, and Z ¹ and Z ² are each independently
—COO— or —OCO—, and X ¹ and X ² are each independently H or CH ₃ .

It is preferred to use a composition containing one compound of the formula Ia, one compound of the formula Ib and one compound of the formula II. R present in formula Ia is preferably straight-chain alkyl. W present in formulas Ia, Ib and II is preferably H. In formula II, X ¹ preferably represents H and X ² preferably represents CH ₃ . Bifunctional mesogenic compounds of the formula II and formula Ia
By varying the concentration of the monofunctional compound of formula Ib and formula Ib, the degree of crosslinking of the polymer film can be influenced. This makes it possible to control the properties of the films, such as optical parameters and their temperature dependence, glass transition temperature, thermal and mechanical stability and solvent resistance.

The amount of the compound of the formula Ia in the polymerizable mesogenic composition is preferably from 20 to 45%, in particular from 30 to 40%, based on the weight of the total mixture. The amount of the compound of the formula Ib is preferably from 10 to 30%, in particular from 15 to 25%, based on the weight of the total mixture. Formula II
The amount of the compound represented by is based on the weight of the total mixture,
Preferably it is 20-55%, especially 35-50%. The polymerizable mesogenic compounds of the formulas Ia, Ib and II are described in the publications cited above and, for example, in Houben
-Methoden der Organischen Chemie by Weyl, Thiem
It can be produced by a method known per se described in standard academic books on organic chemistry such as e-publisher and Stuttgart.

Compounds of formula II are, for example, DJ
Chemer, 190, 3201-3215 (1989) by Broer et al. Compounds of formula Ia are described in WO 9
7/00843. Without further elaboration, one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Accordingly, the following examples are merely illustrative and do not limit the remainder of the description in any way.

[0028]

DETAILED DESCRIPTION OF THE INVENTION In the above and following examples, unless otherwise stated, all temperatures are uncorrected and
It is given in degrees Celsius and parts and percentages are all by weight. Example 1 Comparative Example The following polymerizable mixture is prepared: Compound (1) 45% Compound (2) 35% Compound (3) 20%

[0029]

Embedded image

Compounds (1) to (3) are described in Makromol. Chem., 190, 3201 to 3215 (1989) by DJ Broer et al.
It can be produced according to the methods described in WO 97/00843 or by methods similar to these methods.
To this polymerizable composition is added 6% by weight of a radical photoinitiator, Irgacure 907, which is available from Ciba Geigy. The polymerizable composition containing the photoinitiator was then added to 2: 1: 1 toluene / xylene /
It is dissolved in a mixture of isopropyl alcohol in an organic solvent at a concentration of 20% by weight. The solution is filtered to remove contaminants and small particles. Two PET sheets (Melinex 401, available from ICI Corp.)
Rub in one direction with a flat aluminum bar covered with velvet. The length of this rubbing is approximately 1000 mm for the first sheet and 2000 mm for the second sheet.

The above solution is applied to each of the first and second PET sheets as a thin film having a thickness of about 12 μm, and then the solvent is evaporated at 55 ° C. The mixture is then heated at 30-40 ° C.
It is cured by irradiating it with ultraviolet light having a wavelength of 360 nm and an illuminance of 20 mW / cm ² for several seconds. In this way, two polymer thin films 1A and 2B are obtained which can be used as optical retardation films. A thin film A1 having a rubbing length of 1000 mm was obtained on a PET sheet, and a thin film A2 having a rubbing length of 2000 mm was obtained on a PET sheet.

Example 2 Prior to dissolving the polymerizable composition in the organic solvent mixture, a non-ionic fluorocarbon surfactant, Fluorad FC171 (from 3M Co.) was added to the polymerizable composition, respectively.
Are prepared in the same manner as in Example 1 except that the polymer thin film is added at a concentration of 1000 ppm to produce two polymer thin films B1 and B2. A thin film B1 having a rubbing length of 1000 mm was obtained on the PET sheet, and a thin film B2 having a rubbing length of 2000 mm was obtained on the PET sheet. Example 3: Use Examples 1 and 2 The retardation R of the thin films A1, A2, B1 and B2 was determined according to the rubbing direction and also in the rubbing direction with an Olympus polarizing microscope using a Berek compensation film. Was measured at various incident angles θ. In this measurement, each thin film was made of PET
Separated from the substrate and attached to a TAC substrate, then placed on a glass slide. The results are shown in Table 1 below.

Table 1: Retardation R (nm) at various incident angles θ

[Table 1]

The retardation R of the optical retardation film according to the present invention depends on the tilt angle φ between the optical axis of the thin film and the plane of the thin film and the incident angle θ of light, and according to the following equation (1): It can be expressed as the product of the birefringence △ n and the thickness d of the thin film: R (θ, φ) = △ n (θ, φ) d (1) where △ n (θ, φ) is Birefringence, which is defined by the following equation:

[0035]

(Equation 1) Wherein, n _e and n _o are respectively the extraordinary ray and the ordinary ray refractive index of the polymerized mesogenic material.

The numerical value _{n e} and _{n o} is, Abbe (Abb
e) It can be measured using a refractometer, while the retardation R (θ, φ) can be measured as described above at various angles of incidence θ. Therefore, the specified thickness d
The average tilt angle φ for the optical retardation films according to the invention described in Examples 1 and 2 has the measured retardation R, the angle of incidence θ of the light incident on the thin film and the equation (1 ) And n according to (2)
from the measured values of _e and n _o, can be calculated. In the case of the polymer thin films A1, A2, B1 and B2,
As measured by an Abbe's (Abbe) refractometer, _{n e} is 1.64
, And the and _{n o} is 1.50. The R values measured for various angles of incidence θ are shown in Table 1. The average tilt angles obtained are shown in Table 2 below.

Table 2: Tilt angle φ of optical retardation films of Examples 1 and 2

[Table 2] The above results show that, according to the method of the present invention involving the use of a surfactant, producing an optical film exhibiting high quality planar orientation of the polymerized mesogenic material and having a tilt angle that has been reduced to almost zero. It clearly demonstrates that you can do it.

Example 4 The following polymerizable composition is prepared: Compound (1) 35% Compound (2) 10% Compound (3) 15% Compound (4) 40%

[0039]

Embedded image

Compounds (1) to (4) are described in Makromol. Chem., 190, 3201 to 3215 (1989) by DJ Broer et al.
It can be produced according to the methods described in WO 97/00843 or by methods similar to these methods.
In this polymerizable composition, a surfactant, Fluorad FC1
71 (available from 3M Co.) 0.5% by weight
And 6% by weight of a radical photoinitiator, Irgacure 907 (available from Ciba Geigy).
The polymerizable composition containing the photoinitiator and the surfactant is then dissolved in a 3: 7 cyclohexanone / toluene organic solvent mixture at a concentration of 25% by weight. The solution is filtered through a 0.2 micron filter to remove contaminants and small particles. This solution is applied on a PET sheet rubbed as described in Example 1 and then cured to give a 1 μm thick polymer film with planar orientation. The nematic director of the film is essentially parallel to the plane of the film.

The above examples were prepared using the reagents and / or operating conditions generally or specifically described in the present invention instead of the reagents and / or operating conditions used in these examples. It can be repeated with similar results. From the above description, those skilled in the art can easily recognize the essential features of the present invention and adapt the present invention to various uses and conditions without departing from the spirit and scope of the invention. Various changes and modifications can be made.

 ──────────────────────────────────────────────────続 き Continuation of front page (71) Applicant 591032596 Frankfurter Str. 250, D-64293 Darmstadt, Federal Republic of Germany (71) Applicant 599032534 Rockwell International Corporation United States 91358, Thousand Oaks, No. 91, California, USA (72) Inventor Nicholas Sharples, Federal Republic of Germany −64293 Darmstadt Frankfurter Straße 250 (72) Inventor Gabriel Eagan Germany Day −64293 Darmstadt Frankfurter Straße 250 (72) Inventor David Coates Federal Republic of Germany Day −64293 Darmstadt Frankfurter Strasse 250 (72) Inventor Young Chan Germany Day 64293 Darmstadt Frankfurter Strasse 250 (72) Inventor Zimmer Tsang Doi Republic of the Netherlands Day-64293 Darmstadt Frankfurter Straße 250 (72) Inventor Giri Lie Germany Day-64293 Darmstadt Frankfurter Strasse 250 (72) Inventor Bruce K. Winker Germany Day-64293 Darmstadt Frankfurter Straße 250 (72) Inventor Jane H. Hanamoto Germany Day-64293 Darmstadt Frankfurter Strasse 250

Claims (11)

[Claims] 1. An anisotropic polymer material layer having an optical axis substantially parallel to the layer plane, comprising the following steps: a) dissolved in an organic solvent at a concentration of up to 50% by weight A) a polymerizable mesogenic composition consisting essentially of the following components: a) 10 to 50% by weight of one or two polymerizable mesogenic compounds of the formula Ia and one or two of the formulas Ib The polymerizable mesogenic compound represented by 5-35
% By weight: Wherein W is H or CH ₃ , n is an integer from 3 to 6, and R is carbon atom 1 to
An alkyl or alkoxy group having 8); b) a polymerizable mesogenic compound 15 represented by the following formula II:
６０60% by weight: Wherein W is H or CH ₃ , n is an integer from 3 to 6, Z ¹ and Z ² are each independently —COO— or —OCO—, and X ¹ and X ² is each independently H or CH
₃ ) and c) 0.1 to 8% by weight of a photoinitiator; applied in layers to a substrate; b) orienting the polymerizable mesogen composition to a homogeneous orientation; c) exposing to ultraviolet light. An optical retardation film obtained by a method comprising: i) polymerizing the polymerizable mesogen composition; and d) removing the substrate from the polymerized material, if necessary. Prior to or during step a), the following formulas III and IV: (In each formula, n is an integer of 4 to 12, and x is
A mixture of nonionic fluoroalkyl-alkoxylate surfactants selected from the group consisting of 5 to 15) is added to the polymerizable mesogenic composition in an amount of 50 to 2500 ppm; and ii) as a substrate: Using a PET or TAC film, in step a) of the above method, applying the polymerizable mesogen composition onto the substrate, and iii) prior to step a) of the above method, The optical retardation film obtained by a method characterized in that a surface adjacent to the polymerizable mesogen composition is rubbed in one direction or covered with a polyimide layer rubbed in one direction. . 2. The optical retardation film according to claim 1, wherein the tilt angle between the plane of the anisotropic polymer material layer and the optical axis is 0 to 1 degree. 3. The mixture of nonionic fluoroalkyl-alkoxylate surfactants comprises at least two compounds of the formula I
3. The optical retardation film according to claim 1, wherein the compound represented by II is contained in an amount of 100 to 1200 ppm. 4. The mixture of nonionic fluoroalkyl-alkoxylate surfactants comprises at least two compounds of the formula I
The optical retardation film according to any one of claims 1 to 3, wherein the compound represented by V is contained in an amount of 800 to 1800 ppm. 5. A compound of formula II wherein X
¹Is H and X ²Is CH₃And Z¹But-
COO- and Z²Is -OCO-
An optical laser according to any one of claims 1 to 4, characterized in that:
Retardation film. 6. The method according to claim 1, wherein the polymerizable mesogen composition is one or more.
At least one of the following formulas V: Wherein W, n and R have the meanings indicated for formula I, from 5 to 50% by weight
Characterized in that it is further contained in an amount of:
The optical retardation film according to any one of the above. 7. In the formulas Ia, Ib, II and V:
The optical retardation film according to claim 1, wherein W is H. 8. In step (a), PET is used as the substrate.
Using a film, and prior to step a), this PE
The optical retardation film according to any one of claims 1 to 7, wherein a surface of the T film adjacent to the polymerizable mesogen composition is rubbed in a single direction. 9. A method for producing an optical retardation film according to claim 1. 10. Use of the optical retardation film according to claim 1 in a liquid crystal display. 11. A liquid crystal display device comprising a liquid crystal cell and the optical retardation film according to claim 1.