JP4727581B2 - Polymer film with twist pattern - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a polymer film comprising a polymerized chiral liquid crystal material having a helically twisted structure with a pattern of regions having different twists. The invention further relates to a method for producing such a film and its use in liquid crystal displays or other optical elements, components or devices.

Background and prior art retardation films are commonly used in liquid crystal displays to switch between linear and circular polarization. In the literature, layers of polymerized liquid crystal (LC) compounds, also known as reactive mesogens (RM), can be produced to provide a retardation layer, for example RMS03001 (Merck KGaA, Darmstadt, Germany) Is a commercially available RM solution that can be spin-coated and photopolymerized to provide planar nematic films. By changing the spin coating speed, films of different thicknesses can be produced, and as a result, half-wave and quarter-wave retardation films can be produced.

  Non-patterned twist retardation films have been previously reported in WO 02/73301. For example, by adding a chiral dopant to a polymerizable nematic host such as the commercially available RMS03001 (Merck KGaA, Darmstadt, Germany), the oriented chiral films disclosed in eg GB 2330360 and WO 02/73301 are also good Can be manufactured. The produced chiral film has a helical arrangement of RM molecules throughout the thickness of the film. The direction of the helix introduced into the RM layer depends on the direction of chirality of the chiral dopant used (from left or right). In this way, films with either a left or right twist of the helix depending on the dopant used can be produced. The degree of chirality imparted to the RM film (ie, the number of helical turns present throughout the film) also depends on the concentration of dopant added and the HTP of the chiral dopant.

However, as the displays become more demanding, for example, switchable two-dimensional (2D) / 3-dimensional (3D) displays disclosed in US 6,437,915 and US 6,046,849, which can be used for mobile phones, for example It is rapidly desired to be able to pattern the retardation layer for the parallax barrier layer in
EP 1 295 929 discloses a patterned twisted film showing a pattern of areas with different twist directions used as decorative or security markings. These films are made from a layer of polymerizable chiral LC mixture containing two chiral dopants with opposing twist directions. The net twist of the mixture is given by the twisting power and concentration of the respective dopant. One of the dopants can be photoisomerized and changes the twisting force by light irradiation. Thus, to produce a patterned film, the reticulated twist can be changed in selected areas of the layer by light irradiation and the twisted structure is fixed by heat or photopolymerization.

In the cholesteric polymer film disclosed in EP 1 295 929, the helix has a relatively short pitch of the array of visible light wavelengths, and such different regions are either from the right or the left from the circularly polarized visible light. To selectively reflect.
However, in many applications, such as the 2D / 3D displays described above, visible light is delayed, thereby providing a retardation layer, ie, a twisted A-plate retarder, suitable for TN or STN type devices. Long pitch chiral helix is required.
WO 98/57223 discloses the use of chiral photoisomerizable compounds for the production of multi-domain liquid crystal displays having different regions with different twist directions (handling). However, no mention is made of a coated polymer film.
WO 02/07330 discloses the use and advantages of a twisted A-plate retarder. However, the twisted A-plate retarder film of WO 02/07330 cannot be easily patterned, for example, as required by the parallax barrier in 2D / 3D displays described in US 6,437,915 and US 6,046,849. It does not provide a simple method for producing a simple patterned retardation film.

As reported in US 6,437,914 in the article "3D Display Hardware Research at Sharp Labs: an update" published in Sharp Technical Journal Issue # 74 1999 A method for producing a patterned RM film used as a parallax barrier is described. However, this method is complex and involves many steps. For example:
1. 2. Cover and fire the polyimide 2. Polish the polyimide at 90 ° 3. Cover the polyimide with a photoresist. 4. Pre-fire the photoresist. 5. Use a photomask to selectively irradiate the photoresist. Create photoresist (wash photoresist from irradiated area)
7). 8. Bake the photoresist. Polish the exposed polyimide at 8.45 °. 9. Remove remaining photoresist 10. Cover RM layer on polyimide Polymerizing the RM layer Accordingly, there is a need for an improved patterned retardation film and an improved manufacturing method thereof that do not have the disadvantages of prior art films and methods.

An object of the present invention is to provide an improved patterned retardation film and a method for producing the same. Other objects of the invention will be immediately apparent to the expert from the following description.
The inventors of the present invention provide, in particular, a chiral polymerized liquid crystal material by providing the retardation film described in the present invention and a method for manufacturing the same, and the pattern or different of twisted and untwisted regions. It has been found that an anisotropic film showing a pattern of a region having a twist angle can achieve these objects and solve the above problems.

The present invention uses a polymerizable liquid crystal material containing a low concentration of a photoisomerizable chiral dopant to obtain a photopatternable retardation film. Such a film, for example, has the following steps:
1. 1. Coating and baking polyimide 2. Polishing the polyimide 3. coating the RM layer on the polyimide; 4. irradiating the RM layer through a photomask; The step of polymerizing the RM layer can be produced with much fewer steps than the prior art methods described above.
The use of low concentrations of chiral dopants also allows a wide range of existing polymerisables without the need to specifically scale up a series of new polymerizable liquid crystal materials (which need to be used at much higher concentrations). Such a liquid crystal host material is desirable because it can be easily applied to the film of the present invention.

  Another advantage of the present invention is that a patterned twist retardation layer can be produced, each region having a different twist. This makes it possible to build a retardation film that can only delay light from different regions and change from linear to annular polarized light or maintain it as delayed linearly polarized light, based solely on the degree of twist. it can.

SUMMARY OF THE INVENTION The present invention relates to a patterned polymer comprising a polymerized chiral liquid crystal (LC) material having a pattern of at least two regions and / or a pattern of at least one twist region and at least one non-twist region having different twist angles. Related to film.
The invention further provides a helical twist in a given twist direction in the chiral material and is convertible between at least two states with different twist forces, wherein the conversion of the chiral compound is effected by light irradiation. At least one first chiral compound, and-a helical twist in the chiral material in the opposite torsional direction to the first chiral compound, resulting in a different twist under the same conditions as the first chiral compound At least one second chiral compound that is not convertible between two or more states having force,
Providing a layer of polymerizable chiral LC material comprising: irradiating a selected region of the layer with light irradiation that alters the degree of chirality of the first chiral compound; and polymerizing the selected region To a method for producing a polymer film as described herein.

The invention further relates to a compensator, retarder, or retarder of a polymer film as described herein in a liquid crystal display or other optical element, component or device, in particular a switchable two-dimensional (2D) / 3-dimensional (3D) display. It relates to the use as a polarizer.
The invention further relates to a liquid crystal display, optical element, component or device, in particular a 2D / 3D display, comprising a polymer film as described herein.

Definition of Terms As used in this application, the term “film” refers to a self-supporting film having more or less significant mechanical stability and flexibility, ie, a free-standing film and a supporting substrate. (Substrate) includes a coating or layer on or between two substrates.
The term “liquid crystal or mesogenic material” or “liquid crystal or mesogenic compound” refers to a material or compound containing one or more rod-like, plate-like or disc-like mesogenic groups, ie groups capable of producing liquid crystal phase behavior. Should. A compound or material containing a mesogenic group does not necessarily have to exhibit a liquid crystal phase itself. It may also exhibit liquid crystal phase behavior only when polymerized with mixtures with other compounds or mesogenic compounds or materials or mixtures thereof.

The term “helical twisted structure” relates to a film comprising one or more liquid crystal material layers, in which the mesogens are oriented with the main molecular axis in the preferred direction within the molecular sublayer, with different sub-layers. Such preferred orientation direction in the layer is twisted about the helical axis, where the helical axis is substantially perpendicular to the film plane, ie substantially parallel to the film normal. This definition includes 75-90 °, preferably 80-90 °, particularly preferably 85-90 ° and most preferably 88-90 ° helical axis orientation relative to the film plane.
The term “quarter wave film” or “QWF” means an optical film that provides a phase difference of π / 2 between two orthogonal linear polarization states propagating in an anisotropic material.
The term “half-wave film” or “HWF” means an optical film that provides a phase difference of π between two orthogonal linear polarization states propagating in an anisotropic material.

式中、ｐは、第１の近似での分子らせんのピッチｐであり、多くの実用的用途では十分なものであって、ｃは、液晶ホストにおけるキラルドーパントの濃度である。 Detailed Description of the Invention The present invention takes advantage of the ability to control the helical twisting force (HTP) of a chiral dopant to obtain either a twisted or planar retardation film. The chiral dopant HTP exhibits the ability to twist the LC host material and is represented by formula (1). :

Where p is the pitch of the molecular helix p in the first approximation, which is sufficient for many practical applications, and c is the concentration of the chiral dopant in the liquid crystal host.

The polymer film of the present invention preferably coats a thin layer of polymerizable chiral LC material on a substrate and orients the material such that the axis of the molecular helix is oriented substantially perpendicular to the plane of the layer, It is produced by changing the chirality of selected portions of the layer by light irradiation and fixing the chiral structure by polymerization to obtain a patterned polymer film.
The polymerizable chiral LC material comprises at least two chiral compounds having different twist directions. The first chiral compound is, for example, a photoisomerizable chiral compound whose HTP is changed by isomerization by light irradiation at a predetermined wavelength or light irradiation at a predetermined wavelength and intensity. The second chiral compound does not change its HTP under the same conditions as the first compound. For example, the second chiral compound may be a non-isomerizable compound whose HTP does not change at all when irradiated with light. The second chiral compound may be a photoisomerizable chiral compound in which HTP changes upon irradiation with light having a wavelength and / or intensity different from that used for the first chiral compound.

  Here, the change in the total twist angle at selected portions of the polymerizable chiral LC material can be obtained by appropriate selection of the amount of first and second chiral compounds and HTP. For example, suitable chiral LC materials include photoisomerizable and non-isomerizable chiral compounds, one of which is levorotatory and the other is dextrorotatory. The isomerizable compound, for example, has a larger absolute HTP and / or is present in excess compared to the non-isomerizable compound, so that the reticulated twist direction of the chiral LC material is The twist direction of the first chiral compound is the same. A chiral compound that is photoisomerizable by photoirradiation of selected portions of the chiral LC material is converted to a form having a different HTP, for example, its torsional force partially or chirally converts the chiral material into a lower HTP chiral material It can be reduced by complete conversion, while the HTP of chiral compounds that are not isomerizable does not change. As a result, the network twist angle of selected portions of the chiral LC material is much smaller than the non-selected portion, or the network twist angle of selected regions of the chiral LC material is zero, i.e., these In this part, the material exhibits a non-twisted structure.

Patterned polymer films of the present invention having high twist angles that reflect visible wavelengths of light can also be produced. In the case of a film having a pattern of regions that are high but have different twist angles, these regions exhibit different reflection colors. Such a film can be used, for example, as a color filter.
However, films having a pitch larger than the visible wavelength range, particularly those having a pitch greater than 1 μm are more preferred.
After a change in chirality as described above at a selected portion of the polymerizable chiral LC material, the material is polymerized as such to permanently fix the chiral structure on the selected portion of the LC material or in its entirety. The polymerization is performed, for example, by photopolymerization or thermal polymerization. Photopolymerization is preferred. Particularly preferred polymerization of the LC material is initiated by the same light irradiation as that used to change the chirality of the first chiral compound.

A preferred method for producing the patterned retardation film of the present invention comprises the following steps:
1. providing a layer of alignment material by coating the substrate, preferably with polyimide and optionally firing or curing;
2. Optionally, polishing an orientation material such as polyimide in a certain direction to provide a preferred orientation direction;
3. coating the alignment layer with a layer of the photopolymerizable chiral LC material above or below,
4. Irradiate the LC material through the photomask to create a pattern of regions with different twists in the layer to provide photoisomerization of the isomerizable chiral dopants in the regions not covered by the photomask Step,
5, polymerizing the LC layer to permanently fix the twist pattern;
including.

Another preferred embodiment of the invention relates to an anisotropic polymer film made from a polymerizable chiral LC material that does not polymerize in the presence of oxygen or polymerizes only slowly. Suitable chiral LC materials in this embodiment can be prepared, for example, by selecting a suitable photoinitiator that does not react or does not react well in the presence of oxygen. The film irradiates selected regions of the polymerizable material with light irradiation that changes the HTP of the first chiral compound in the presence of oxygen such that polymerization is hindered or inhibited; It can be produced by polymerizing a selected region or the entire material in the absence of oxygen.
The preferred polymerization of the polymerizable chiral LC material in this embodiment is faster than the isomerization of the first chiral compound, and the chirality of the unpolymerized portion of the LC material does not change during photopolymerization, or at least Does not change substantially.

In chiral materials, for example, using low intensity irradiation to polymerize in selected regions and then using higher intensity to polymerize the entire material, or different to initiate isomerization and polymerization It is also possible to polymerize without any isomerization by using the wavelength.
An anisotropic film according to this preferred embodiment is produced by coating a substrate with a polymerizable chiral LC material in the presence of oxygen, for example, in an air atmosphere, and irradiating selected areas of the coating with light. be able to. This is achieved, for example, by irradiating through a photomask. Alternatively, the selected region can be irradiated by a finely focused irradiation source such as a laser. While light irradiation results in a change in chirality in selected areas of the LC material described above, the chirality in non-selected areas remains unchanged. Polymerization of the entire coating is hindered by the presence of oxygen. Thereafter, the entire coating is polymerized, for example, by thermal polymerization or photopolymerization, in the absence of oxygen, to immobilize the selected region and the chiral structure in the non-selected region. This is done, for example, by polymerization under an inert gas or by coating with a coating of an oxygen barrier layer such as a PET film. As a result, a patterned film having different chiralities and twist angles in the selected region and the non-selected region is obtained.

Instead, the anisotropic polymer film in this preferred embodiment can be obtained by a method comprising the following steps in the presence of oxygen.
(A) providing a layer of a photopolymerizable chiral LC material that does not polymerize in the presence of oxygen and comprises the first and second chiral compounds described above,
(B) 1 ) coating selected areas of the layer with a substrate , and irradiating the layer with light irradiation that alters the twisting power of the first chiral compound and initiates polymerization of the chiral polymerizable material; Here, the substrate has the properties of an oxygen barrier layer and is permeable to light irradiation,
2) Repeating the procedure of step B1 one or more times for at least one region of the layer not coated with the substrate in the previous step.

In step B1, the chiral LC material is polymerized only in the region of the layer coated with the substrate, excluding oxygen, which is transparent to light irradiation and can inhibit the polymerization. Since polymerization is faster than isomerization, the chiral structure of the coated region is permanently fixed before it substantially changes. In uncovered areas, polymerization is hindered by the presence of oxygen, and isomerization and thereby a change in chirality can occur. The altered chiral structure at the part not previously coated in step B2 is fixed by polymerizing under a permeable oxygen barrier substrate.
As a result, a patterned film having different chiralities and twist angles in the covered region and the uncoated region in Step B1 is obtained.

Preferably, the irradiation in step B1 is performed at a sufficiently high intensity and / or long enough that the first chiral compound is fully isomerized in the uncoated region, so that the change in chirality is complete. In step B2, all of the uncovered areas are polymerized, i.e. step B2 is performed only once.
However, it is also possible to perform the irradiation in step B1 so that the chirality in the uncovered region changes only to some extent by, for example, low irradiation intensity or short irradiation time. In the first step B2, irradiation is made through the oxygen barrier substrate only in some of the areas not previously coated in step B1 in order to fix the polymerized and changed structure, while in the areas not yet coated the second Or further isomerization can occur, which is fixed in further step B2. Accordingly, patterned films having different areas greater than 2 with different twist angles can be produced.

Instead of the above-described particularly preferred embodiment of the material that does not polymerize in the presence of oxygen, a polymerizable chiral LC material that polymerizes in air is used and low intensity irradiation and material are used to isomerize selected regions of the material. Higher intensity irradiation can also be performed to polymerize.
The polymerizable chiral LC material used in the production of the anisotropic polymer film of the present invention is preferably a chiral smectic or chiral nematic liquid crystal material. Chiral nematic liquid crystal materials are particularly preferred.
The polymerizable chiral LC material is preferably dissolved or dispersed in an organic solvent and polymerizes or crosslinks during or after evaporation of the solvent.

The amount of dopant and HTP is such that the starting mixture before isomerization has a non-twisted structure (ie racemic) and is twisted by photoisomerization, or the starting mixture has a twisted structure and photoisomerization Can be selected to be racemic and non-twisted.
Another preferred embodiment of the present invention relates to a patterned film having a pattern of at least two regions having different twist angles.
Another preferred embodiment of the present invention relates to a patterned film having a pattern of at least one twist region and at least one non-twist region.
Another preferred embodiment of the present invention relates to the initial racemic mixture that produces either a quarter wave or half wave retardation film during coating and polymerization. Such mixtures can be photoisomerized to produce twisted retardation films either from the left or from the right.

  Another aspect of the invention relates to a patterned film having a different twisted area pattern and / or a twisted and non-twisted area pattern, where the twist is in particular a twist so that the film does not reflect visible light. The spiral pitch in the region is selected to be greater than 1 μm. This layer is advantageous for use as, for example, a retardation film that does not reflect visible light, such as the cholesteric film described in the prior art, but for example visible light to compensate for phase shifts that occur in liquid crystal display devices. Causes a phase shift. Usually, the twist angle in such a retardation film is in the range of ~ 360 ° greater than 0 °. Only a small amount of chiral compound is required in such a film compared to a cholesteric film because only a low twist is required.

Particularly preferred embodiments of the present invention are:
At least one region of 0 ° twist angle, and at least one region of greater than 0 to + 270 ° or less than 0 to −270 ° twist angle, at least one region of 0 ° twist angle, and at least 1 greater than 0 to + 180 ° or less than 0 to −180 ° twist angle region −at least one 0 ° twist angle region and at least one greater than 0 to + 90 ° or less than −− 90 ° twist angle region-at least two regions with different twist angles selected from + 90 ° to -90 ° not 0 °-at least one 0 ° twist angle region and at least one + 90 °-- 90 ° twist angle region—having at least three twist angles selected from 0 to + 90 ° or −90 ° to 0, each preferably having a small twist angle It relates to a patterned film having regions with at least one ± 90 °, ± 75 ° and ± 60 ° twist angle, preferably all regions having the same twist angle indication.

  FIG. 1 shows by way of example and schematically a patterned film (1) of a preferred embodiment of the invention comprising a region (2) having a 0 ° twist and a region (3) having, for example, a 90 ° twist. . The film comprises a calamitic uniaxial positive birefringence polymerized LC material having a planar orientation, wherein the mesogens of the LC molecules in region (2) are oriented on the film plane in the direction indicated by the double arrows. Region (3) is twisted around a helical axis perpendicular to the film plane with a 90 ° twist angle (indicated by a set of arrows). The effective retardation of linearly polarized light of wavelength λ that is transmitted through the film (1) is linearly polarized by the polarizer (4) in the direction indicated by the double arrow, but is not twisted region (2 ) Is 0, and in region (3) is λ / 2.

Preferably, the polymerizable chiral LC material is
At least one first chiral compound having a predetermined twist direction and changing HTP upon light irradiation; and-an HTP of the first chiral compound having a twist direction opposite to that of the first chiral compound. And at least one polymerizable compound having at least one polymerizable group and having at least one second chiral compound that does not change its HTP when irradiated with light.

The polymerizable compound can also be the first and / or second chiral compound. Instead, the polymerizable compound is a further polymerizable compound which is preferably a liquid crystal or a mesogen.
Very preferably, the polymerizable chiral LC material is
a1) at least one first chiral compound whose chirality changes with a given twisting direction and light irradiation and which may also be polymerizable and / or mesogenic,
a2) It has a twist direction opposite to that of the first chiral compound, the chirality of the first chiral compound does not change when irradiated with light, and the polymer is polymerizable and / or mesogenic. At least one second chiral compound,
b) at least one polymerizable mesogenic compound comprising at least one polymerizable group, and c) a polymerization initiator.
Particularly preferred compounds used as the first and second chiral compounds are those having a high helical twisting power (HTP), so that the amount of chiral compound in the material can be reduced.

Chiral compounds that can be used in the present invention whose chirality changes upon irradiation with light are known to experts. For example, suitable and preferred compounds are those that are exposed to light irradiation by reactions including, but not limited to, photoisomerization, photoinduced 2 + 2 cycloaddition, photo-fries arrangement, or equivalent photolysis processes. It is a photosensitive chiral compound whose structure or shape changes.
Particularly preferred and preferred are photoisomerizable chiral compounds that exhibit EZ or cis-trans isomerization upon photoirradiation, thereby changing to forms with different HTPs and determining the pitch of different amounts of liquid crystal material. It is. Further preferred and preferred are photolytic or (photo) variable chiral materials (TCM) that change from chiral to achiral or racemic mixtures upon photoirradiation because their chirality is destroyed by photodetachment or photocleavage at chiral centers. ).

For example, suitable photoisomerizable chiral materials are P. van de Witte et al., Liq. Cryst. 24 (1998), 819-27, J. Mat. Chem. 9 (1999), 2087-94 and Menton, camphor, nopinone derivatives or chiral stilbenes described in Liq. Cryst. 27 (2000), 929-33 and A. Bobrovski et al., Liq. Cryst. 25 (1998), 679-687 Is included. Suitable TCMs containing photocleavable carboxylic acid groups or aromatic keto groups attached to a chiral center are described in US 5,668,614. In addition, F. Vicentini, J. Cho and L. Chien, Liq. Cryst. 24 (1998), 483-488 describe binaphthol derivatives as TCM and their use in multicolor cholesteric displays.
Particularly preferred are P. van de Witte et al., Liq. Cryst. 24 (1998), 819-27, J. Mat. Chem. 9 (1999), 2087-94 and Liq. Cryst. 27 (2000). , 929-33 and A. Bobrovski et al., Liq. Cryst. 25 (1998), 679-687, a polymerizable and photoisomerizable chiral material comprising menthone, camphor, nopinone derivatives or chiral stilbenes It is.
Furthermore, polymerizable and photoisomerizable chiral compounds described in WO 02/40614 are preferred.

The polymerizable chiral LC material further comprises a second chiral compound that does not change its chirality under the same conditions as the first chiral dopant. Preferably, the second chiral compound is a compound that is not isomerizable. It may be polymerisable or non-polymerizable and may also be a mesogen or a liquid crystal.
Suitable chiral dopants are, for example, commercially available R- or S-811, R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, R- or It can be selected from S-5011 or CB 15 (Merck KGaA, Darmstadt, Germany). Particularly preferred are chiral compounds having a high helical twisting power (HTP), in particular compounds containing a sorbitol group as described in WO 98/00428, compounds containing a hydrobenzoin group as described in GB 2,328,207, WO 02/94805 WO 02/06196 and WO having the described chiral binaphthyl derivatives, the chiral binaphthol acetal derivatives described in WO 02/34739, the chiral TADDOL derivatives described in WO 02/06265 and at least one fluorinated linking group and a terminal or central chiral group It is a compound containing the chiral compound described in 02/06195.

Particularly suitable chiral compounds which are polymerizable and not isomerizable can be used from the following description.
In addition to the chiral compound, the polymerizable LC material preferably comprises at least one achiral polymerizable mesogenic compound having at least one polymerizable functional group.
In a preferred embodiment, the polymerizable LC material comprises at least one chiral or achiral polymerizable mesogenic compound (2 or polyreactive or bifunctional or bifunctional compound) having two or more polymerizable functional groups. Including. Upon polymerization of such a mixture, a three-dimensional polymer network is formed, which is self-supporting and exhibits high mechanical and thermal stability and low temperature dependence of physical and optical properties. Varying the concentration of polyfunctional mesogenic or non-mesogenic compounds facilitates polymer film crosslink density and thereby physical and chemical properties, especially temperature dependence of optical properties, thermal and mechanical stability and solvent resistance Can be adjusted.

The polymerizable mesogens 1,2- and polyreactive compounds used in the present invention are known per se, for example standard academic books on organic chemistry, such as Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, It can be produced by the method described in Stuttgart.
Examples of suitable polymerizable mesogenic compounds that can be used as monomers or comonomers with the compounds according to the invention in polymerizable LC mixtures are, for example, WO 93/22397, EP 0 261 712, DE 195 04 224, WO 95/22586, WO 97/00600 and GB 2 351 734. However, the compounds disclosed in these references are merely examples and should be considered as not limiting the scope of the invention.

Examples of particularly useful chiral and achiral polymerizable mesogenic compounds (reactive mesogens) are given in the following list, which is illustrative only and is intended to illustrate the invention without any limitation:

上記式において、Ｐは、重合可能な基であり、好ましくは、アクリル、メタクリル、ビニル、ビニルオキシ、プロペニルエーテル、エポキシ、オクセタンまたはスチリル基であり、ｘおよびｙは、１〜１２の同一または異なる整数であり、Ａは、Ｌ^１によって任意に１、２または３置換された１，４−フェニレンであり、または１，４−シクロヘキシレンであり、ｕおよびｖは、それぞれ独立して０または１であり、Ｚ^０は、−ＣＯＯ−、−ＯＣＯ−、−ＣＨ_２ＣＨ_２−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−または単結合であり、Ｒ^０は、極性基または非極性基であり、Ｔｅｒは、たとえば、メンチルなどのテルペノイド基であり、Ｃｈｏｌは、コレステリル基であり、Ｌ、Ｌ^１およびＬ^２は、それぞれ互いに独立してＨ、Ｆ、Ｃｌ、ＣＮまたは任意にハロゲン化した１〜７個の炭素原子を有するアルキル、アルコキシ、アルキルカルボニル、アルキルカルボニルオキシ、アルコキシカルボニルまたはアルコキシカルボニルオキシ基であり、ｒは、０、１、２、３または４である。上式におけるフェニル環は、任意に１、２、３または４個のＬ基で置換されている。

In the above formula, P is a polymerizable group, preferably an acrylic, methacrylic, vinyl, vinyloxy, propenyl ether, epoxy, oxetane or styryl group, and x and y are the same or different integers of 1-12. And A is 1,4-phenylene optionally substituted by L ¹ , or 1,4-phenylene, or 1,4-cyclohexylene, and u and v are each independently 0 or 1 Z ⁰ is —COO—, —OCO—, —CH ₂ CH ₂ —, —CH═CH—, —C≡C— or a single bond, and R ⁰ is a polar group or a nonpolar group. , Ter is, for example, a terpenoid radical like menthyl, Chol is a cholesteryl group, L, ^{L 1} and ^{L 2} are H each independently of the other, F, Cl, CN or Is an optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy, alkoxycarbonyl or alkoxycarbonyloxy group having 1-7 carbon atoms, and r is 0, 1, 2, 3 or 4. . The phenyl ring in the above formula is optionally substituted with 1, 2, 3 or 4 L groups.

式中、Ｒ^１およびＲ^２は、互いに独立して上で定義したＲ^０またはＰであり、ａおよびｂは、０また１であり、Ｚは、Ｚ^０であり、Ａ^１およびＡ^２は、互いに独立して上で定義したＡである。 In this regard, the term “polar group” refers to F, Cl, CN, NO ₂ , OH, OCH ₃ , OCN, SCN, optionally fluorinated alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy having up to 4 carbon atoms. Or an alkoxycarbonyloxy group or a group selected from 1-, oligo- or poly-fluorinated alkyl or alkoxy groups having 1 to 4 carbon atoms. The term “nonpolar group” means an optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having one or more, preferably 1 to 12 carbon atoms. And means not included in the above definition of “polar group”.
Particularly preferred polymerizable and photoisomerizable chiral compounds described in WO 02/40614 are compounds of the following formula:

Wherein R ¹ and R ² are independently of each other R ⁰ or P as defined above, a and b are 0 or 1, Z is Z ⁰ , A ¹ and A ² are , A defined above independently of each other.

  Polymerization of the polymerizable chiral LC material is accomplished by exposure to heat or actinic radiation. Actinic radiation means irradiation with light such as UV light, IR light or visible light, irradiation with X-rays or gamma rays or irradiation with high energy particles such as ions or electrons. Preferably the polymerization is carried out by light irradiation, particularly preferably by UV irradiation. As a source of actinic radiation, for example, a single UV lamp or a set of UV lamps can be used. When using a large lamp power, the curing time can be reduced. Other possible sources of light irradiation are lasers, for example UV lasers, IR lasers or visible lasers. The light irradiation used for the polymerization is preferably of the same wavelength as that used for changing the chirality of the polymerized LC material, particularly preferably of the same wavelength and intensity.

The polymerization is carried out in the presence of an initiator that absorbs at the wavelength of actinic radiation. For example, when polymerizing with UV light, a photoinitiator can be used that can generate free radicals or ions that are decomposed under UV irradiation to initiate the polymerization reaction. When curing a polymerizable mesogen having an acrylate or methacrylate group, preferably a radical photoinitiator is used, and when curing a polymerizable mesogen having a vinyl and epoxide group, preferably a cationic photoinitiator Is used. A polymerization initiator that decomposes when heated to produce free radicals or ions that start polymerization can also be used.
Photoinitiators for radical polymerization include, for example, commercially available Irgacure (R) 651, Irgacure (R) 184, Darocure (R) 1173 or Darocure (R) 4205 ( All from Ciba Geigy AG), and in the case of cationic photopolymerization, commercially available UVI 6974 (Union Carbide) can be used. The polymerizable LC material preferably contains a polymerization initiator in an amount of 0.01 to 10%, very preferably 0.05 to 5%, in particular 0.1 to 3%. UV photoinitiators are preferred, and radical UV photoinitiators are particularly preferred.
The photoinitiator can also be selected so that the chiral material does not polymerize or does not polymerize well in the presence of oxygen as described above. For example, Irgacure (R) 907 is preferably used when polymerization in air is required, and Irgacure (R) 369 is used with materials that do not polymerize well in air.

The curing time depends in particular on the reactivity of the polymerizable mesogenic material, the thickness of the coating layer, the type of polymerization initiator and the output of the UV lamp. The curing time in the present invention is preferably less than 10 minutes, particularly preferably less than 5 minutes, very particularly preferably less than 2 minutes. For mass production, a short curing time of 3 minutes or less, very preferably 1 minute or less, especially 30 seconds or less is preferred.
The polymerizable liquid crystal mixture of the present invention further comprises one or more other suitable components such as catalysts, sensitizers, stabilizers, chain transfer agents, inhibitors, co-reacting monomers, surfactants. Compound, Smoothing agent, Wetting agent, Dispersing agent, Hydrophobing agent, Adhesive, Fluidity improver, Antifoaming agent, Deaerator, Diluent, Reactive diluent, Auxiliary agent, Coloring agent Dyes or pigments may be included.

Also, the addition of up to 20% of non-mesogenic compounds having 2 or 3 or more polymerizable functional groups to the polymerizable LC material to increase polymer cross-linking can be achieved with bifunctional or polyfunctional polymerization. It can be done instead of or in addition to possible mesogenic compounds to increase the crosslinking of the polymer.
A typical example of a bifunctional non-mesogenic monomer is an alkyl diacrylate or alkyl dimethacrylate having an alkyl group with 1 to 20 C atoms. Typical examples of non-mesogenic monomers having more than 2 polymerizable groups are trimethylpropane trimethacrylate or pentaerythritol tetraacrylate.
In other preferred embodiments, the mixture of polymerizable materials comprises up to 70%, preferably 3-50%, of non-mesogenic compounds having one polymerizable functional group. Typical examples of monofunctional non-mesogenic monomers are alkyl acrylates or alkyl methacrylates.

The optical retardation film of the present invention can be used for a retardation or compensation film of a conventional LCD, particularly DAP (deformation of alignment layer) or, for example, ECB (electric field control birefringence), CSH (color super homeotropic), VAN. Or a VA (vertical alignment) system, such as a VAC (vertical alignment nematic or cholesteric) display, MVA (multi-domain vertical alignment) or PVA (patterned vertical alignment) display, OCB (optically compensated bend cell or optically compensated birefringence), Bend mode or hybrid type display displays such as R-OCB (reflective OCB), HAN (hybrid oriented nematic) or pi-cell (π-cell) displays, plus TN (twisted nematic), HTN (advanced nematic) Re-nematic) or STN (super twisted nematic) display, IPS (in-plane switching) display, also known as AMD-TN (active matrix drive TN) display or “super TFT” display, ISP (etc.) A display using liquid crystals in the optically isotropic phase described in, for example, WO 02/93244 A1, switchable two-dimensional (2D) disclosed in US 6,437,915 and US 6,046,849 / 3D (3D) display, CRT (CRT) display or organic light emitting diode (OLED).
Particular preference is given to TN, STN, VA and IPS displays, in particular active matrix types, and also 2D / 3D displays.

The films of the present invention can also be used in other applications than those described above, such as alignment layers, optical filters or polarizing beam splitters, optical waveguides or decorative or security applications.
In a preferred embodiment, the film of the present invention is not outside the switchable LC cell of the display, but is usually a glass substrate, between the substrates forming the switchable LC cell and comprising the switchable LC medium. Used as an optical retardation film for LCD (incell use).
Compared to conventional displays where an optical retarder is usually placed between the LC cell and the polarizer, the in-cell application of the optical retardation film has some advantages. For example, a display in which an optical film is attached to the outside of a glass substrate forming an LC cell usually can have a parallax problem and can greatly impair viewing angle suitability. Forming a retardation film inside the LC display cell can reduce or even avoid these parallax problems.

The LCD of this embodiment preferably includes:
1) leading to the center starting from the edge of the cell in the order described below, the following elements 11) at least one is permeable to incident light, each other face flat row of first and second substrates 12) An array of non-linear electrical elements on one of the substrates that can be used to individually switch individual pixels of the LC cell, wherein the elements are transistors, particularly preferably TFTs, etc. The arrangement, preferably an active element,
13) A color filter array provided on one of the substrates, preferably on the opposite side of the substrate having an array of non-linear elements, wherein the color filter is optionally a planarization layer Coated with the array,
14) a first electrode layer 15 provided inside the first substrate 15) an optional second electrode layer 16 provided inside the second substrate 16) the first and second electrodes Optional first and second alignment layers 17 provided above) a liquid crystal (LC) cell comprising an LC medium that can be switched between at least two different states by applying an electric field;
2) a first linear polarizer on one side of the LC cell 3) an optional second linear polarizer on the side of the LC cell opposite to the side of the first linear polarizer, and 4) at least of the present invention LCD comprising one patterned optical retardation film, wherein the patterned optical retardation film 4) is between the first and second substrates of the LC cell, preferably between the color filter and the LC medium, very preferably , Between the color filter and one of the electrode layers or, if a planarization layer is present, between the planarization layer and one of the electrode layers.
The following examples illustrate the present invention without limiting it. Above and below, unless otherwise indicated, all temperatures are stated in degrees Celsius and all percentages are by weight.

イルガキュア（登録商標）６５１は、光開始剤、イルガノックス（登録商標）１０７６は、安定剤であり、ともに市場で入手可能である（Ciba AG, Basel, Switzerland）。ＦＣ１７１（登録商標）は、非イオン性過フッ化炭素界面活性剤（3M Co.）である。 Example 1
A polymerizable nematic LC mixture M1 was prepared as follows.

Irgacure (R) 651 is a photoinitiator and Irganox (R) 1076 is a stabilizer, both available on the market (Ciba AG, Basel, Switzerland). FC171® is a non-ionic fluorocarbon surfactant (3M Co.).

Mixture M1 was heated and stirred to ensure good mixing. The M1 sample had a clearing temperature of 74 ° C. measured.
M1 was dissolved in PGMEA (propylene glycol monomethyl ether acetate) at a concentration of 40% to form the host mixture H1. To this host mixture H1 was added 0.1% of a non-isomerizable chiral dopant Dni and 0.08% of a photoisomerizable chiral dopant Di.

The solution was spin coated (2000 RPM) on two glass / polished polyimide (JSR AL1054) slides. One of the films is photopolymerized immediately after coating (20 mWcm ^-2 , UV-a, 60s, N ₂ ), the other is photopolymerized (20 mWcm ^-2 , UV-a, 60s, N ₂ ) Previously photoisomerized (20 mWcm ⁻² , 365 nm, 30 s, air). The transmittance of each film was measured between cross-stretched linear iodine polarizers (cut at 45 ° with respect to the stretching direction). Transmission values were recorded using a Hitachi U2000 spectrophotometer. The RM film was mounted on a homemade sample stage that could be rotated 360 ° while the polarizer maintained the same orientation. FIG. 2 shows a plot of transmission data as a function of RM film rotation, obtained when the RM film is rotated 360 ° between crossed polarizers.
The transmission plot of the first film produced (non-isomerized) shown in graph (a) of FIG. 2 has four maxima that predict that the first film is a planar non-twisted retardation layer. It is shown that. The plot of the isomerized film shown in graph (b) of FIG. 2 shows that the film has roughly equivalent transmission at all angles, which is characteristic of a helically twisted retardation film. .

Example 2
A patterned retardation layer was produced using the mixture of Example 1. The solution is spin coated (2000 RPM, 30 s) on a polished polyimide / glass slide and isomerized with a photomask that allows either 100% or 0% UV light transmission (20 mWcm ⁻² , 365 nm, 60 s, air) The resulting film was photopolymerized (20 mWcm ⁻² , UV-a, 60 s, N ₂ ). A photograph viewed from above the light box through the crossed polarizer is shown in FIG.
FIG. 3 shows that the film has patterned, twisted (isomerized) and non-twisted (non-isomerized) regions. As shown, it is possible to produce a striped retardation film by aligning the direction of the polarizer with the orientation of the RM molecules in the non-isomerized region.

FIG. 2 schematically shows a polymer film (1) of the present invention comprising a non-twisted region (2) and a twisted region (3) and combined with a polarizer (4). FIG. 4 shows transmission data for rotation angles of non-isomerized polymer film (a) and isomerized polymer film (b) produced according to Example 1 and rotated 360 ° between crossed polarizers. . FIG. 6 shows a photograph of the polymer film of Example 2 including twisted and non-twisted regions viewed through crossed polarizers in a light box.

Claims (25)

A patterned polymer film comprising a polymerized chiral liquid crystal (LC) material,
At least two regions of the pattern and / or at least one torsion region and at least one pattern of the non-helical region have a different twist angles possess,
The helical pitch in the twist region is greater than 1 μm,
Obtained from a polymerizable chiral LC material comprising at least two chiral compounds having different twist directions, wherein the first chiral compound changes its helical twisting power (HTP) upon irradiation with light, The chiral compound of 2 does not change its HTP under the same conditions as the first compound, and the amount and HTP of the chiral compound is such that the first polymerizable chiral LC material before light irradiation has a non-twisted structure. Selected to be twisted by irradiation,
The polymer film characterized by the above.   The polymer film according to claim 1, wherein the polymer film has a pattern of at least two regions having different twist angles. 3. A polymer film according to claim 1 or 2 , characterized in that it has a pattern of at least one twisted region and at least one non-twisted region.   Initially obtained from a polymerizable racemic chiral LC material, when coated and polymerized, produces either a quarter-wave or half-wave retardation film, producing either a left or right twisted retardation film The polymer film according to claim 1, wherein the material is photoisomerized before polymerization.   5. The method according to claim 1, comprising at least one region of 0 ° twist angle and at least one region of twist angle greater than 0 to + 270 ° or less than 0 to −270 °. The polymer film described in 1.   5. The method according to claim 1, comprising at least one region of 0 ° twist angle and at least one region of twist angle greater than 0 to + 180 ° or less than 0 to −180 °. The polymer film described in 1.   5. The method according to claim 1, comprising at least one region of 0 ° twist angle and at least one region of twist angle greater than 0 to + 90 ° or less than 0 to −90 °. The polymer film described in 1.   5. The polymer film according to claim 1, wherein the polymer film has at least two regions having different twist angles selected from −90 ° to + 90 ° which are not 0 °.   5. A torsion angle region selected from at least one 0 [deg.] Torsion angle region and at least one non-0 [deg.] -90 [deg.] To +90 [deg.]. Polymer film.   5. The polymer film according to claim 1, wherein the polymer film has at least three regions having different twist angles selected from 0 to + 90 ° or −90 ° to 0. 6. A helical twist in a predetermined twist direction in the chiral material, which can be converted between at least two states with different twist forces, wherein the conversion of the chiral compound can be effected by light irradiation, at least 1 One first chiral compound, and two or more having a helical twist in the opposite twist direction to the first chiral compound in the chiral material and having a different twisting force under the same conditions as the first chiral compound At least one second chiral compound that is not convertible between the states of
Providing a layer of polymerizable chiral LC material comprising
Here, the amount of chiral compound and HTP are selected so that the first polymerizable chiral LC material before light irradiation has a non-twisted structure and is twisted by light irradiation,
Chirality selected areas of the layer with light irradiation varying degrees of the first chiral compound is irradiated, characterized by a polymerizable child said selected region,
A method for producing a patterned polymer film comprising a polymerized chiral liquid crystal (LC) material . The method according to claim 11, characterized in that the first chiral compound is a photoisomerizable chiral compound and the second chiral compound is a non-isomerizable chiral compound. 13. A process according to claim 11 or 12, characterized in that the polymerization of the chiral LC material is initiated by light irradiation which changes the twisting force of the first chiral compound. The following steps:
1. providing a layer of alignment material on the substrate;
2, optionally polishing the alignment material in a certain direction to produce a preferred alignment direction;
3. Coating the alignment layer with a layer of chiral LC material that is photopolymerizable,
4. irradiating the LC layer through the photomask to produce photoisomerization of the isomerizable chiral dopant in the areas not covered by the photomask, creating a pattern of areas with different twists in the layer;
5, polymerizing the LC layer to permanently fix the twist pattern,
The features and-law containing A method according to any one of claims 11 to 13. Polymerization of the polymerizable chiral LC material is hindered in the presence of oxygen, where a selected region of the polymerizable material is irradiated with light irradiation in the presence of oxygen that alters the chirality of the first chiral compound. The method according to any one of claims 11 to 14, characterized in that the selected region or the entire material is polymerized in the absence of oxygen. 16. The method of claim 15, wherein irradiation of selected areas of polymerizable material is performed through a photomask. 16. The method of polymer film according to claim 15, wherein irradiation of selected areas of the polymerizable material is performed by a finely focused irradiation source. The following steps in the presence of oxygen:
A) providing a layer of a photopolymerizable chiral liquid crystal material that does not polymerize in the presence of oxygen and comprises the first and second chiral compounds of claim 11;
B) 1) coating selected areas of the layer with a substrate and irradiating the layer with light irradiation that alters the twisting power of the first chiral compound and initiates polymerization of the chiral polymerizable material, wherein And the substrate has the properties of an oxygen barrier layer and is transparent to light irradiation, and 2) the layer of the layer not covered with the substrate in the previous step one or more times in step B1. Repeating for at least one region;
The including method according to any one of claims 11 to 17. 19. A twist structure comprising at least one region having a twist angle different from at least one other region obtained by the method according to claim 11, wherein the helical pitch in the twist region is from 1 μm. is large, patterned polymer fill beam comprising polymerized chiral liquid crystal (LC) material. Use of the polymer film according to any of claims 1 to 10 and 19 as a compensator, retarder or polarizer in a liquid crystal display or other optical element, component or device. The use of the film according to any one of claims 1 to 10 and 19 as an optical retardation film of an LCD, wherein the film is located between substrates of a switchable LC cell, To use. Comprising a polymer film according to any one of claims 1 to 10 and 19, a liquid crystal display, an optical element, component or device. LC cell formed by two plane-parallel substrates, wherein at least one of the two plane-parallel substrates is transparent to incident light and is provided inside at least one of the two transparent substrates And an LCD comprising an electrode layer, optionally with an alignment layer placed thereon, and an LC medium present between two substrates that can be switched between at least two different states by applying an electric field, wherein the LCD is LC 20. The LCD comprising at least one film according to any of claims 1 to 10 and 19 , located between two plane-parallel substrates forming cells.   24. LCD according to claim 22 or 23, characterized in that it is a TN, STN, VA, IPS, ISP or 2D / 3D display. 1) the following elements 11) starting from the end of the cell to the center in the order described below: 1) first and second substrates parallel to each other, at least one of which is transparent to incident light;
12) An array of non-linear electrical elements on one of the substrates that can be used to individually switch individual pixels of the LC cell, wherein the elements are transistors, particularly preferably TFTs, etc. The arrangement is preferably an active device,
13) A color filter array provided on one of the substrates, preferably on the opposite side of the substrate having an array of non-linear elements, the color filter optionally coated with a planarizing layer The filter array,
14) a first electrode layer provided inside the first substrate;
15) an optional second electrode layer provided inside the second substrate;
16) Optional first and second alignment layers provided on the first and second electrodes,
17) LC media that can be switched between at least two different states by applying an electric field;
A liquid crystal (LC) cell comprising
2) a first linear polarizer on one side of the LC cell;
3) any second linear polarizer on the LC cell side opposite to the first linear polarizer side, and 4) at least one optical retardation according to any of claims 1 to 10 and 19 the film,
The optical retardation film 4) is located between a color filter and an LC medium.

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