JP2000098392A - Method for rubbing substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously rub a long flexible thin film substrate in a rolled shape in a desired inclining direction after drawing out by arranging two rubbing rollers to be in parallel with each other and to rotate in the directions opposite to each other together with a drawing out roller with respect to the substrate to be rubbed. SOLUTION: Usually two rubbing rollers 2, 4 comprise metal roll cores covered with rubbing cloths composed of flock cloths. In general, both two rubbing rollers 2, 4 are located on the same plane of a substrate 1 and rotate with almost the same rotational speed and with almost the same squeezing depth, however, directions of rotation are opposite to each other as shown by arrows. Thus, two rubbing rollers 2, 4 compensate positional deviations in lateral directions of the thin film substrate 1 to which rubbing is applied in an inclining direction by rotating in the directions opposite to each other. The reason is that the positional deviations in lateral directions of the thin substrate 1 with respect to the two rubbing rollers are in the directions opposite to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rubbing a thin film substrate for aligning a liquid crystal material. The invention also relates to an optical film obtained using the rubbed thin-film substrate in this way and to the use of this film as an optical compensation film or a phase-shift film in optical and electro-optical devices.

[0002]

2. Description of the Related Art Generally, a method of cutting a thin film substrate into a predetermined size and then rubbing the same, or a method of rubbing a glass substrate having a predetermined size, is such that liquid crystal molecules are uniformly aligned. It is employed in the manufacture of liquid crystal (LC) display devices. In the case of a liquid crystal display device using a normal glass substrate, a glass substrate having a predetermined size is rubbed while being held at a predetermined angle with respect to a rubbing table. On the other hand, when a flexible thin film substrate is used, the thin film substrate is wound up on a roll, and the other is unwound and rubbed continuously. The reason for this is that cutting the thin film substrate into pieces, each having a predetermined length, and then rubbing these pieces is problematic and sometimes inadequate.

FIG. 1 shows a conventional method of continuously rubbing a thin film substrate. In this conventional method, the rubbing direction is generally parallel to the transport direction of the thin film substrate to be rubbed. The illustrated alignment film processing system includes a thin film substrate 1, a rubbing table 5, and a rubbing roller 2. This rubbing roller 2
It consists of a metal roller core covered with a rubbing cloth made of flocked fabric. Although not shown,
The surface of the substrate 1 may be covered with an alignment film. As a material for the alignment film, for example, a polyimide resin or a polyvinyl alcohol resin can be used. This alignment film generally has a dry thickness of several tens of nm on the substrate. However, the coating of the substrate with such an alignment film is not always necessary and can be omitted. In many cases, when directly rubbing a thin film substrate that is not covered by such an alignment film, the rubbed substrate becomes
It has sufficient orientation-control power.

[0004] As shown in FIG.
Is moved forward by the roll 3 and then comes into contact with the rubbing roller 2 so that the thin film substrate is rubbed and then wrapped around the roll 4. In this step, the rubbing roller 2 rotates so that the moving substrate 1 is kept in contact. Thereby, this substrate 1
Rubbing is performed in a direction parallel to the substrate transport direction.
The latter is indicated by two straight arrows. As a result, the liquid crystal molecules applied on the substrate thus rubbed are oriented such that the principal axis of each molecule is parallel to the thin film transport direction. When a nematic liquid crystal is applied to such a rubbed thin film substrate, the optical axis of the birefringent thin film generated is parallel to the thin film transport direction.

In some cases, depending on the use of the thin film substrate, it is often preferable to rub the thin film substrate in a direction inclined with respect to the thin film transport direction. This makes post-processing of the rubbing step particularly simple. As an example, a quarter wave retardation film or a retardation film used in a twisted nematic liquid crystal display can be manufactured from a nematic liquid crystal material oriented on a rubbed thin film substrate, followed by its optical Lamination can be performed on the polarizing plate such that the axial direction is inclined at a predetermined angle with respect to the light absorption axis of the polarizing plate. Polarizers used for this purpose are usually produced by stretching a synthetic resin film, for example polyvinyl alcohol (PVA), and then adsorbing iodine or a dichroic dye on the resulting film. Thereby, the direction of the absorption axis of the polarizing film becomes parallel to the tensile direction.

After being formed on a continuously rubbed thin-film substrate, the retardation film is rolled into a linearly polarizing film.
In the case of directly laminating by a roll-to-roll method, the light absorption axis of the polarizing film is parallel to the transport direction of the rubbed thin film substrate and the retardation film. In this case, when the thin film substrates are rubbed in a direction parallel to the transport direction, the thin films are directly laminated together on a continuous roll-to-roll line as described above. In some cases, it is not possible to obtain a desired inclination of the optical axes of the polarizing film and the retardation film. As an alternative, it is necessary to cut both of these films into films of predetermined dimensions, and then attach the retardation film to a polarizing film at a predetermined tilt angle.

Therefore, as shown in FIG. 2, a continuous roll-to-roll line for directly attaching a retardation film to a polarizing film requires inclined rubbing,
For this purpose, it is necessary to arrange the rotation axis of the rubbing roller 2 not vertically but at an angle with respect to the thin film transport direction. A method of rubbing a substrate with an inclination angle is described in, for example, Japanese Patent Application, JP06-110059-A, JP07.
-191322-A and JP08-160429-A
It is described in. However, in this method, the thin film 1 to be rubbed receives a pressure in a direction transverse to the thin film transport direction, and in the worst case, wrinkles are generated. Therefore, uniform rubbing of the thin film is difficult.

[0008]

The object of the present invention is, therefore, to provide a roll form which does not have the above-mentioned disadvantages or which, if at all, has a small extent.
An object of the present invention is to provide a method of continuously rubbing a flexible thin film substrate having a long length in t) in any desired inclination direction after unwinding.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for unwinding a long flexible thin film substrate provided with a roll format and then continuously rubbing in any desired tilt direction. This method is applied to a continuous roll-to-roll line in which a birefringent thin film of liquid crystal material prepared on a thin film substrate so rubbed directly adheres to the unwound roll-shaped polarizing film. According to the present invention, a method of rubbing a roll-shaped thin film substrate to be unwound includes two rubbing rollers which are parallel to each other,
And arranging the substrate to be unwound and rubbed with a roller so as to rotate in the opposite direction.

Accordingly, the present invention relates to a method of rubbing a thin film substrate for orienting a liquid crystal material, the method comprising the steps of rubbing two substrates such that their axes of rotation are parallel to each other and rotate in opposite directions. The rubbing roller is disposed on the substrate. The present invention also provides
The present invention relates to an optical retardation film obtained by polymerizing an oriented polymerizable liquid crystal material coated on a substrate rubbed by the above method. The present invention also relates to the use of such an optical retardation film in an optical device or an electro-optical device.

FIG. 3 shows a preferred embodiment of the present invention. In FIG. 3, 1 is a rolled-out thin film substrate; 2 is a first roller (A) of two rubbing rollers; 3 is a shift of a conveyed thin film substrate in a lateral direction. 4 is a second roller (B); 6 is a means for detecting (this is, for example, an optical edge sensor provided on a rubbing table);
Is a thin film take-up roll; and 7 is a thin film take-up roll. The two rubbing rollers (A) and (B) usually consist of a metal roll core covered with a rubbing cloth made of flocked fabric. In general, the two rubbing rollers (A) and (B) are both located on the same surface of the substrate 1 and are rotating at almost the same speed and at almost the same indentation depth. The direction of rotation, as indicated by the arrow,
The opposite.

The means 3 for detecting the displacement of the transported thin film substrate in the horizontal direction is not essential to the present invention and can be omitted. By rotating in opposite directions, two rubbing rollers (A) and (B)
Compensates for the lateral displacement of the thin film substrate on which the rubbing is performed in the inclined direction. The reason for this is that the lateral displacement of the thin film substrate is in the opposite direction for the two rollers. Therefore, in this state, the displacement of the rubbed thin film substrate in the lateral direction is suppressed. According to the method of the present invention, the thin film substrate is set at 0 with respect to the substrate transport direction.
Rubbing can be performed at any desired angle of 90 °. Preferably, this rubbing angle is between 0 and 60 °, especially between 0 and 40 °. The rubbing angle is more preferably 30-60 °, and very preferably 40-50 °. Thereby, the liquid crystal material coated on the substrate thus rubbed can be oriented with an optical axis inclined at any angle of 0 to 90 ° with respect to the substrate transport direction.

[0013] Thus, the method of the present invention can, for example, form a rubbed thin film substrate for a retardation film, so that its optic axis is the light absorption of the polarizing film to which the retardation film is attached. A retardation film inclined at a desired angle with respect to the axis is formed. Therefore,
The method of the present invention can be applied to a continuous roll-to-roll line where the retardation film and the polarizing film can be directly integrated by lamination, which is a particular advantage in the art. A preferred embodiment of the present invention comprises one or two
One or more of the following parameters: a) the rotational speed of one of the two rubbing rollers, b) its pressure on the substrate, and c) its indentation depth on the substrate. It is characterized in that the rotation speed of the rubbing roll, its pressure on the substrate, and its indentation depth on the substrate can be kept constant.

Preferably, the data detected by the edge sensor 3 arbitrarily provided on the rubbing table 5 is returned to a rubbing controller, which is a parameter that can be changed by the two rollers. One or more of the parameters a) to c) of one of the rollers, preferably of the first roller (A), is controlled, whereby the lateral position of the entire substrate to be rubbed is determined. Small deviations can be corrected immediately and accurately. As an example, if the rubbed thin film substrate shifts to the right as shown in FIG. 3, the roll (A) is adjusted so that its indentation depth increases, while the rubbed thin film substrate is When the roll (A) shifts to the left, the roll (A) is adjusted so that the pressing depth decreases. In this way, the lateral displacement of the thin film substrate can be automatically corrected.

In single roller rubbing systems conventional in the prior art, changing the indentation depth and the rotation speed of the rubbing roller during a rubbing operation is undesirable because it causes non-uniform alignment of the liquid crystal molecules. Was. The method of the present invention can avoid this problem by using two rubbing rollers. As substrate, in principle, all flexible thin-film substrates known to the person skilled in the art for this purpose can be used. Preferably,
The substrate is made of a soft plastic thin film, for example, polyethylene terephthalate (PET), polyvinyl alcohol (P).
VA), a thin film of polycarbonate (PC) or triacetyl cellulose (TAC), particularly preferably
It is a PET thin film or a TAC thin film. The thin film substrate is preferably a long flexible thin film with a roll form.

The liquid crystal material used in the method according to the invention can in principle be selected from all types of liquid crystal materials known in the art. Particularly preferred materials are polymerizable liquid crystal compounds, side-chain or main-chain linear or cross-linked liquid crystal polymers, liquid crystal oligomers, or mixtures of these materials. The thin film substrate continuously rubbed by the method of the present invention is preferably used for forming a birefringent optical film for a liquid crystal display device. This involves applying a polymerizable liquid crystal material onto the rubbed substrate, thereby orienting the liquid crystal material itself in a uniform alignment, and then subjecting the aligned liquid crystal material to UV irradiation in the presence of a polymerization initiator. Exposure can be achieved by in-situ polymerization. For a detailed description of the in-situ polymerization of liquid crystal materials, see, for example, D.S. J. Makrom by Broer et al.
ol. Chem. , 190 , p. 2255 et seq. (198
Found in 9).

Preferably, rubbing of the substrate, formation of a birefringent film on the substrate and any application of this birefringent film to another film, such as a polarizing film, an adhesive film, a diffusion film, a release film or a protective film, etc. Lamination can be performed in one continuous process on the same production line. The polymerizable liquid crystal material preferably contains one or more polymerizable liquid crystal compounds having at least one polymerizable group capable of undergoing linear polymerization or cross-linking polymerization by ultraviolet irradiation. The polymerizable group is preferably a vinyl, vinyloxy, acrylate, methacrylate, chloroacrylate, styrene, epoxy or propenyl ether group. Further, a mixture containing a liquid crystal compound having one polymerizable group and a liquid crystal compound having two polymerizable groups is also preferable. In this case, the polymerizable group in the mixture and the polymerization in one compound are preferably used. The sex groups may be the same or different. Further suitable polymerizable liquid crystal materials are described, for example, in WO 98 / 04651-A, WO 98/00475 and WO 98 / 12584-A, which are hereby incorporated by reference in their entirety.
The birefringent film of liquid crystal material formed on the rubbed substrate can be used as an optical retardation film or compensation film, or a retardation film in a liquid crystal display or other optical or electro-optical devices.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS Without further elaboration, persons skilled in the art will, from the preceding description, appreciate the full scope of the present invention. Therefore, the following examples are merely illustrative and should not be construed as limiting the rest of the description in any way. Example 1 A 127 μm film of triacetyl cellulose, Fujitac (registered trade name of a product commercially available from Fuji Film, Japan) was used as a substrate. The substrate was placed under two rubbing rollers rotating in opposite directions as shown in FIG. 3 and rubbed by these rollers. The rotation axes of these two rubbing rollers are arranged at an angle of 45 ° in the direction perpendicular to the film transport direction. Each of these rubbing rollers has an outer diameter of 100 mm and a flocked fabric YA20R [this fabric is manufactured by Yoshikawa Che
available from Micro Industry (Japan)] was used. The transport speed of the thin film substrate is 3 m / min, and the rotation speed of the rubbing rollers A and B is:
It was 120 rpm. The indentation depth of these rollers with respect to the substrate was 0.4 mm.

After rubbing in this manner, a polymerization initiator Darocur 628 is applied to the rubbed surface of the substrate using a micro-gravure coater.
5 (available from Ciba Geigy AG) was added and polymerizable nematic liquid crystal material RMM14 diluted with toluene to a solids content of 20% by weight (Merck KGaA, D
armstadt, available from Germany) to form a uniform layer on this surface. This nematic liquid crystal material RMM14 has a birefringence Δn of 0.144 and exhibits the following phase behavior: K (crystal) 40 ° C. N
(Nematic) 138 ° C I (isotropic).
The substrate thus coated was passed through a drying oven at 45 ° C. for 6 minutes, thereby evaporating the solvent, and then the liquid crystal layer thereon was cured by irradiation with ultraviolet rays. The dried and cured liquid crystal layer thus had a thickness of 2 μm.

The phase difference of the light polarized in the direction perpendicular to the optical axis of the liquid crystal layer formed here was 280 nm. This is about の of the center wavelength of visible light. The optical axis of this liquid crystal layer substantially corresponds to the direction in which the thin film substrate was rubbed. That is, it is inclined at an angle of 45 ° with respect to the substrate transport direction. When a 1 / 2-wave retardation film is combined with a polarizing film to induce a 90 ° rotation of the polarization direction of the incident light polarized there, the retardation film is 45 ° relative to the transmission axis of the polarized light. Must be oriented at an angle of ゜. In the case of this combination, the retardation film produced in the present invention can be directly laminated with the intended polarizing film in a continuous roll-to-roll line. The method according to the invention has particular advantages for this application.

Example 2 An 80 μm film of triacetyl cellulose, Fujitac [Fuji Film (Japan)]
A registered product name of a product commercially available from is used as a substrate. The substrate was rubbed as illustrated in FIG. The rotation axes of the two rubbing rollers had an angle of 45 ° in the direction perpendicular to the film transport direction. Each of these rubbing rollers is 100m
m, and the rubbing roller is provided with a flocked fabric YA20R [this fabric is made of Yoshikawa
a Chemical Industry (Japan)] was used. The transport speed of the thin film substrate is 4
m / min, and the rotation speed of rubbing rollers A and B was 200 rpm. The indentation depth of these rollers with respect to the substrate was 0.5 mm.

After rubbing in this manner, the polymerization initiator Darocur 628 was applied to the rubbed surface of the substrate using a micro-gravure coater.
55% by weight and polymerized nematic liquid crystal material RMM14 diluted with toluene to a solids content of 16% by weight (Merck KGaA, Da
rmstadt, manufactured by Germany) to form a uniform layer on this surface. The coated substrate is passed through a drying oven at 65 ° C. for 2 minutes,
Thereby, the solvent was evaporated, and then the liquid crystal layer thereon was cured by irradiation with ultraviolet rays. After drying, this liquid crystal layer
It had a thickness of 1 μm. The phase difference of the light beam polarized in the direction perpendicular to the optical axis of the liquid crystal layer formed here is:
It was 144 nm. This is about 1 center wavelength of visible light.
/ 4. The optical axis of this liquid crystal layer was at an angle of 45 ° to the substrate transport direction. When combining a 1/4 wavelength film with a polarizing film to change linearly polarized light into circularly polarized light, the retardation film must be oriented at an angle of 45 ° to the transmission axis of the polarized light. No. In this combination, the film produced in the present invention can be directly laminated to the intended polarizing film in a continuous roll-to-roll line. The method according to the invention has particular advantages for this application.

Example 3 A stretched 75 μm film of polyester, Lumilar (registered trade name of a product commercially available from Toray, Japan) was used as the substrate.
The substrate was rubbed as illustrated in FIG. The rotation axes of the two rubbing rollers had an angle of 45 ° in the direction perpendicular to the film transport direction. Each of these rubbing rollers has an outer diameter of 100 mm, and these rubbing rollers have a flocked fabric YA20R [this fabric is made of Yoshikawa
Available from Chemical Industry (Japan). The transport speed of the thin film substrate is 4 m /
And the rotation speed of the rubbing rollers A and B was 200 rpm. The indentation depth of these rollers with respect to the substrate was 0.5 mm.

After rubbing in this manner, the polymerization initiator Darocur 628 was applied to the rubbed surface of the substrate using a micro-gravure coater.
55% by weight and polymerized nematic liquid crystal material RMM14 diluted with toluene to a solids content of 16% by weight (Merck KGaA, Da
rmstadt, manufactured by Germany) to form a uniform layer on this surface. The substrate coated in this way is passed through a drying oven at 85 ° C. for 7 minutes,
Thereby, the solvent was evaporated, and then the liquid crystal layer thereon was cured by irradiation with ultraviolet rays. After drying, this liquid crystal layer
It had a thickness of 1 μm. The phase difference of the light beam polarized in the direction perpendicular to the optical axis of the liquid crystal layer formed here is:
142 nm. This is about 1 center wavelength of visible light.
/ 4. The optical axis of this liquid crystal layer was at an angle of 45 ° to the substrate transport direction.

An acrylic adhesive diluted with a solvent was applied on the thin film. After drying, the film was rolled.
The polarizing film was laminated with a two-roll line. Just prior to the winding step of the resulting laminate, the polyester substrate was separated from the liquid crystal layer. When a 1/4 wavelength film is combined with a polarizing film to convert linearly polarized light into circularly polarized light, the retardation film must be oriented at an angle of 45 ° to the transmission axis of the polarized light. In this combination, the film produced in the present invention can be directly laminated to the intended polarizing film in a continuous roll-to-roll line. The method according to the invention has particular advantages for this application.

Example 4 A stretched 75 μm film of polyester, Lumilar (registered trade name of a product commercially available from Toray, Japan) was used as the substrate.
On this substrate, using a micro-gravure coater, γ-
Polyimide resin AL-10 diluted with butyrolactone
51 (this is Japan Synthetic Ru
bber) and then 12
After drying at 0 ° C. for 10 minutes, an alignment film was formed thereon.
The film was then rubbed as illustrated in FIG. The rotation axes of the two rubbing rollers had an angle of 45 ° in the direction perpendicular to the film transport direction. Each of these rubbing rollers is 100mm
And these rubbing rollers have
Flocked fabric YA20R [This fabric is made of Yoshika
wa Chemical Industry (Japan)] was used. The transport speed of the thin film substrate is 6
m / min, and the rotation speed of rubbing rollers A and B was 200 rpm. The indentation depth of these rollers with respect to the substrate was 0.5 mm.

After rubbing in this manner, a polymerization initiator Darocur 628 was applied to the rubbed surface of the substrate using a micro-gravure coater.
55% by weight and polymerized nematic liquid crystal material RMM14 diluted with toluene to a solids content of 16% by weight (Merck KGaA, Da
rmstadt, manufactured by Germany) to form a uniform layer on this surface. The coated substrate is passed through a drying oven at 65 ° C. for 2 minutes,
Thereby, the solvent was evaporated, and then the liquid crystal layer thereon was cured by irradiation with ultraviolet rays. After drying, this liquid crystal layer
It had a thickness of 1 μm. The retardation of a light beam polarized in a direction perpendicular to the optical axis of the liquid crystal layer formed here was 142 nm. This is about ４ of the central wavelength of visible light. The optical axis of this liquid crystal layer was at an angle of 45 ° to the substrate transport direction.

An acrylic adhesive diluted with a solvent was applied on the thin film. After drying, the film was rolled.
The polarizing film was laminated with a two-roll line. At this time, the polyester substrate was separated from the liquid crystal layer immediately before the winding step of the resulting laminate. When a 1/4 wavelength film is combined with a polarizing film to convert linearly polarized light into circularly polarized light, the retardation film must be oriented at an angle of 45 ° to the transmission axis of the polarized light. In this combination, the film produced in the present invention can be directly laminated to the intended polarizing film in a continuous roll-to-roll line. The method according to the invention has particular advantages for this application.

Example 5 An 80 μm film of triacetyl cellulose, Konicacac [Konica
(Japan) was used as the substrate. The substrate was rubbed as illustrated in FIG. The rotation axes of the two rubbing rollers had an angle of 20 ° in the direction perpendicular to the film transport direction. Each of these rubbing rollers is 100mm
And the rubbing roller is provided with a flocked fabric YA20R [this fabric is made of Yoshikawa
Manufactured by Chemical Industry (Japan)] was used. The transport speed of the thin film substrate was 12 m / min, and the rotation speed of the rubbing rollers A and B was 400 rpm. The indentation depth of these rollers with respect to the substrate was 0.4 mm.

During the rubbing process, the displacement of the position of the thin film substrate to be rubbed was detected by the sensor 3 and corrected by the signal of the sensor 3. Specifically, when the thin film substrate is shifted to the left, the pressing depth of the roller (A) in FIG. 3 is reduced by 0.1 to 0.3 mm, and when the thin film substrate is shifted to the right, the pressing depth is reduced. Was increased by 0.1 to 0.5 mm. This change caused a change in the thin film transport speed and the rotation speed of the roller (A), but this did not cause wrinkling of the rubbed thin film, and the film was uniformly oriented. After rubbing in this manner, a micro-gravure coater (manufactured by
Polymerizable liquid crystal material R diluted with toluene to a solids content of 25% by weight using YASUI Seiki)
M257, which is manufactured by Merck
Was applied to form a uniform layer on the surface. This RM
257 shows the phase behavior of K 71 ° C. N 126 ° C. I.

The substrate coated in this manner is kept at 60 ° C.
For 2 minutes in a drying oven, which evaporates the solvent,
Next, the liquid crystal layer thereon was cured by ultraviolet irradiation.
After drying, the liquid crystal layer had a thickness of 3.6 μm. The phase difference of the light beam polarized in the direction perpendicular to the optical axis of the liquid crystal layer formed here was 520 nm. It is approximately at the center wavelength of visible light. The optical axis of this liquid crystal layer was at an angle of 20 ° to the substrate transport direction. S
In the TN liquid crystal device, the polarizer must be arranged such that the optical axis of the retarder combined with the polarizer has a specific angle with respect to the transmission axis of the predetermined incident polarized light. In this combination, the film produced in the present invention can be directly laminated to the intended polarizing film in a continuous roll-to-roll line. The method according to the invention has particular advantages for this application.

The foregoing example was repeated, substituting the reactants and / or operating conditions of the present invention as generally and specifically described, for the reactants and / or operating conditions used in the above examples, Similar results can be obtained.
From the foregoing description, those skilled in the art can easily understand the basic characteristics of the present invention and can make various changes and modifications of the present invention without departing from the spirit or scope of the present invention. It can be adapted to various situations and applications.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a conventional continuous rubbing method of a thin film substrate using one rubbing roller.

FIG. 2 is an illustrative view showing a continuous roll-to-roll line rubbing method in which one rubbing roller is used and its rotation axis is arranged at a certain angle, not perpendicular to the thin film transport direction.

FIG. 3 shows that the axes of rotation are parallel to each other and rotate in opposite directions according to a preferred embodiment of the present invention;
FIG. 4 is an illustrative view showing a continuous roll-to-roll line rubbing method in which rubbing rollers are arranged at a certain angle, not perpendicular to a substrate;

[Explanation of symbols]

1: thin film substrate; 2: first roller (A); 3: means for detecting a lateral displacement of the thin film substrate to be conveyed; 4: second roller (B); 5: rubbing table; -Forward roll; 7: thin film-take-up roll.

Continuation of front page (71) Applicant 591032596 Frankfurter Str. 250, D-64293 Darmstadt, Federal Republic of Germany (72) Inventor Shun Nakano Wataru Germany Day-64293 Darmstadt Frankfurter Strasse 250

Claims (8)

[Claims] 1. A method for rubbing a thin film substrate for orienting a liquid crystal material, comprising: rubbing two rubbing rollers such that their rotation axes are parallel to each other and the rollers rotate in opposite directions. Rubbing method for rubbing a substrate, wherein the rubbing method is arranged on a thin film substrate. 2. The method according to claim 1, wherein the rotation axes of the two rubbing rollers are inclined at an angle with respect to the transport direction of the thin film substrate. 3. The method according to claim 1, wherein the substrate is a long flexible thin film substrate having a roll format. 4. One or more of the following parameters a) two rubbing rollers, while keeping the rotation speed of the other one rubbing roller, its pressure on the substrate and its pushing depth on the substrate constant. One of
4. The rotational speed of the individual, b) its pressure on the substrate, and c) its indentation depth on the substrate.
The method according to any one of the preceding claims. 5. The method according to claim 1, further comprising detecting a displacement of the position of the thin film substrate in a direction perpendicular to a direction in which the thin film substrate is transported, wherein one or two of the two rubbing rollers have the same parameters. The position shift of the thin film substrate is automatically corrected by changing one or more of a) to c) based on data detected by this means. 4. The method according to 4. 6. The liquid crystal material contains one or more polymerizable liquid crystal compounds, and the polymerizable liquid crystal compound comprises:
At least one polymerizable group capable of undergoing linear polymerization or cross-linking polymerization by ultraviolet irradiation, whereby the initial liquid crystal alignment of the liquid crystal material is fixed to the rubbed thin film substrate. Item 6. The method according to any one of Items 1 to 5. 7. A polymerizable liquid crystal material is applied on a substrate rubbed by the method according to claim 1, and then the oriented liquid crystal material is removed in the presence of a polymerization initiator. An optical retardation film obtained by in-situ polymerization by exposure to ultraviolet radiation. 8. Use of the optical retardation film according to claim 7 as an optical compensation film or a retardation film in an optical device and an electro-optical device.