KR101978796B1 - Liquid crystal display device and Method of fabricating the same - Google Patents

Abstract

An object of the present invention is to provide a transverse electric field driving liquid crystal display device capable of performing a display having higher transmittance while driving liquid crystal molecules at a low voltage, simply and at low cost.
The alignment film is composed of a bottle brush.

Description

Liquid crystal display device and Method of fabricating the same

TECHNICAL FIELD This invention relates to the manufacturing method of a liquid crystal display element and a liquid crystal display element.

As a driving method of the liquid crystal display device, there are twisted nematic (TN), in-plane switching (IPS), ferroelectric liquid crystal (FLC), and the like.

Among them, the IPS method changes the alignment direction of the liquid crystal molecules and performs display by applying an electric field in a direction (lateral direction) parallel to the surface of the liquid crystal molecules charged between the two substrates. Such an IPS type liquid crystal display device is excellent in visual characteristics and is applied to a wide range of devices including mobile phones and televisions.

In the existing liquid crystal display device, the alignment direction of the liquid crystal molecules is adjusted so that the liquid crystal molecules are arranged along a predetermined direction without applying an electric field.

A method of adjusting the alignment direction of liquid crystal molecules in an IPS type liquid crystal panel, comprising: forming an alignment film made of polyimide (PI) on a substrate and rubbing the surface of the alignment film in a predetermined direction with a cloth such as rayon or cotton ( Rubbing method) and the method (photo-alignment method) etc. which irradiate polarized ultraviolet-ray and generate anisotropy on the polyimide film surface, etc. are employ | adopted. By these treatments, the liquid crystal molecules are strongly bound to the substrate surface and are oriented in a constant direction. Thus, patent document 1 is disclosed as a related art of the structure provided with the orientation film.

In the structure of patent document 1, a liquid crystal molecule is strongly restrained by an oriented film. Therefore, even if an electric field is applied to the liquid crystal layer, the alignment direction of the liquid crystal molecules does not change immediately, but the alignment direction of the liquid crystal molecules does not change until a voltage having a predetermined magnitude, that is, a voltage greater than or equal to a threshold value is applied.

In addition, since the liquid crystal molecules are strongly constrained by the alignment film, when an electric field is applied to the liquid crystal layer, the alignment direction of the liquid crystal molecules near the alignment film does not change from the initial alignment direction, and is located in the middle portion (bulk) between the substrates in the liquid crystal layer. Only the liquid crystal molecules to change the orientation direction. In the liquid crystal panel of the IPS system, contrast conversion is performed by using a phase difference (retardation) change accompanying the change in orientation of the liquid crystal molecules as described above.

Generally, the transmittance | permeability of the IPS system liquid crystal panel is represented by the following formula | equation.

Equation 1

Where? Is the liquid crystal molecule alignment angle when voltage is applied to the initial alignment direction,? N is the refractive index anisotropy of the liquid crystal, d is the cell gap, and? Is the wavelength of light.

It can be understood that, if the orientation angle φ, the refractive index anisotropy Δn and the cell gap d are appropriately selected from the above equation, an ideal transmittance of 50% is achieved (black and white type). However, the design parameters of the IPS panel are practically determined in consideration of all conditions such as not only transmittance but also driving voltage, response time and even yield. As a result, the transmittance | permeability of a practical IPS panel falls to about half of an ideal value.

On the other hand, with the practical use of organic electroluminescence (EL) displays, there is a need for even greater improvement of characteristics of liquid crystal displays. In particular, power consumption reduction and brightness (transmittance) improvement have become very important developments to achieve differentiation from organic EL displays, and from this background, there is a strong demand for low voltage driving and high transmittance of IPS panels.

For the request for low voltage driving and high transmittance of such an IPS panel, for example, Patent Document 2 discloses weak anchoring (zero anchoring) on at least one of a comb-shaped electrode substrate or a counter substrate in order to improve transmittance on the electrode. In order to realize the alignment film, a method of producing a polymer brush on the substrate by living radical polymerization is described.

In addition, the term 'zero plane anchoring' in the present specification regulates the alignment of liquid crystal molecules in the horizontal or diagonal direction, but the liquid crystal molecular alignment forcing in the in-plane direction is zero, that is, the liquid crystal molecules are aligned in the horizontal direction with respect to the substrate, but the horizontal plane It means that there is no liquid crystal molecular orientation forcing in the inside.

Patent Document 1: Japanese Patent Publication No. 2940354 Patent Document 2: Japanese Patent Laid-Open No. 2015-125205

However, in order to produce a polymer brush on a substrate, it is necessary to be immersed in a polymerization solution in which monomers are dissolved for each substrate and to perform a long time polymerization reaction at a high temperature under deoxygenation. It was impossible to respond.

In order to solve the above problems and achieve the object, the liquid crystal display device of the present invention is characterized in that the alignment film is composed of a bottle brush.

Moreover, in one Embodiment of this invention, the said bottle brush is equipped with the principal chain and the graft side chain, It is characterized by the above-mentioned.

In one embodiment of the present invention, the graft side chain is covalently bonded to the substrate.

In one embodiment of the present invention, the graft side chain is a copolymer.

In one embodiment of the present invention, the graft side chain is a block copolymer.

Moreover, in one Embodiment of this invention, the said bottle brush is characterized by being crosslinkable.

Moreover, in one Embodiment of this invention, a bottle brush layer is formed in one sheet out of two board | substrates which oppose, and the polyimide layer is formed in another one sheet | seat. It is characterized by the above-mentioned.

Moreover, in one Embodiment of this invention, the said bottle brush layer is formed on the electrode substrate, It is characterized by the above-mentioned.

Moreover, in one Embodiment of this invention, it is driven by the transverse electric field. It is characterized by the above-mentioned.

In an embodiment of the present invention, the anchoring value of the bottle brush layer is smaller than the anchoring value of the polyimide layer.

Moreover, the manufacturing method of the liquid crystal display element of this invention includes the process of forming a bottle brush layer on a board | substrate, the process of injecting a liquid crystal between the said board | substrate which formed the said bottle brush, and the process of orienting the said liquid crystal. It is characterized by.

Moreover, in one Embodiment of this invention, the process of orienting the said liquid crystal is characterized by the rubbing method.

Moreover, in one Embodiment of this invention, the process of orienting the said liquid crystal is characterized by the photo-alignment method.

According to the present invention, a transverse electric field driving liquid crystal display device capable of performing a display having higher transmittance while driving liquid crystal molecules at a low voltage can be manufactured easily and at low cost, and an large substrate can be produced.

1 is a cross-sectional view showing a schematic configuration of a liquid crystal display shown as a first embodiment of the present invention.
FIG. 2 is a diagram showing the liquid crystal molecular alignment direction distribution in the liquid crystal panel of the liquid crystal display shown as the first embodiment, using a liquid crystal having a positive dielectric anisotropy and applying an electric field.
FIG. 3 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a liquid crystal panel of the liquid crystal display shown as the first embodiment, in which a liquid crystal having a positive dielectric anisotropy is used and no electric field is applied.
4 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a state where an electric field is applied using a liquid crystal having a positive dielectric anisotropy in the liquid crystal panel of the liquid crystal display shown as the first embodiment.
5 is a cross-sectional view showing an example of a bottle brush formed on a substrate as a weak anchoring alignment film.
6 is a cross-sectional view showing a schematic configuration of a liquid crystal display shown as the second embodiment.
FIG. 7 is a diagram showing a liquid crystal molecule alignment direction distribution in a liquid crystal panel of the liquid crystal display shown as the second embodiment, in which a liquid crystal having a dielectric constant anisotropy is used and an electric field is applied.
FIG. 8 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a liquid crystal panel of the liquid crystal display shown as the second embodiment, in which a liquid crystal having a dielectric constant anisotropy is used and no electric field is applied.
FIG. 9 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a liquid crystal panel of the liquid crystal display shown as the second embodiment using a liquid crystal having a negative dielectric anisotropy and applying an electric field.
FIG. 10 is a sectional view showing a schematic configuration of a liquid crystal display shown as the third embodiment. FIG.
FIG. 11 is a diagram showing a liquid crystal molecule alignment direction distribution in a liquid crystal panel of the liquid crystal display shown as the third embodiment, using a liquid crystal having a positive dielectric anisotropy and applying an electric field. FIG.
It is sectional drawing which shows schematic structure of the liquid crystal display shown as 4th Embodiment.
It is a figure which shows the liquid-crystal molecular orientation direction distribution in the liquid crystal panel of the liquid crystal display shown as said 4th embodiment, using the liquid crystal whose dielectric constant anisotropy is negative and applying an electric field.
14 is a graph showing the relationship between voltage (V) and transmittance (T) of the liquid crystal panel of Example and the liquid crystal panel of Comparative Example.
15 is a graph showing the relationship between the liquid crystal panel temperature T and the azimuth anchoring strength A2 of the embodiment.
16 is a graph showing the relationship between the liquid crystal panel temperature T and the azimuth anchoring strength A2 of the comparative example.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the form for implementing the liquid crystal display element and liquid crystal display element manufacturing method by this invention is demonstrated based on drawing.

First Embodiment

There exist positive types with positive dielectric anisotropy and negative types with negative dielectric anisotropy in liquid crystal. Positive type liquid crystal has a large dielectric property in the long axis direction of a liquid crystal molecule, and is small in the direction orthogonal to a long axis direction. The negative type has a small dielectric property in the long axis direction of the liquid crystal molecules and large in the direction orthogonal to the long axis direction. In this embodiment, an example in which a positive liquid crystal is used will be described.

1 is a sectional view showing a schematic configuration of a liquid crystal display of the present embodiment. FIG. 2 is a diagram showing the orientation direction distribution of liquid crystal molecules in a state where an electric field is applied using a liquid crystal having a dielectric constant anisotropy in a liquid crystal panel of the liquid crystal display shown as the first embodiment. FIG. 3 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a liquid crystal panel of the liquid crystal display shown as the first embodiment using a liquid crystal having an dielectric constant anisotropy and not applying an electric field. FIG. 4 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a state where an electric field is applied using a liquid crystal having a positive dielectric anisotropy in the liquid crystal panel of the liquid crystal display shown as the first embodiment.

As shown in FIG. 1, FIG. 2, the liquid crystal display 10 is equipped with the liquid crystal panel (liquid crystal display element 11), and the backlight unit 12 which provides light to the liquid crystal panel 11. As shown in FIG.

The backlight unit 12 uniformly irradiates light input from a light source (not shown) provided on the rear surface of the liquid crystal panel 11 toward the surface 11f side from the rear surface 11r side of the liquid crystal panel 11. . The backlight unit 12 transmits, for example, light input from a light source (not shown) provided at one end thereof in a direction parallel to the surface 11f of the liquid crystal panel 11, and transmits the transmitted light to the liquid crystal panel ( The so-called edge light type which irradiates toward the surface 11f side from the back 11r side of 11) can be used. Moreover, the backlight unit 12 is what is called a direct type | mold which irradiates the light input from the light source provided in the back 11r side of the liquid crystal panel 11 toward the surface 11f side from the back 11r side of the liquid crystal panel 11. You can also use

The liquid crystal panel 11 includes a substrate 13A, a substrate 13B, polarizing plates 14A and 14B, an electrode layer 15, a weak anchoring alignment layer 16, a strong anchoring alignment layer 17, and a liquid crystal layer 18. have.

The substrates 13A and 13B are each made of a substrate such as glass or resin, and are arranged in parallel with each other at predetermined intervals.

Examples of the substrate 13B include an array substrate and an opposing substrate. An example of the array substrate is an active matrix array substrate. In an active matrix array substrate, a gate wiring and a source wiring are generally arranged in a matrix on a glass substrate, and active elements such as thin film transistors (TFTs) are formed at the intersections thereof. The pixel electrode is connected.

Moreover, a color filter substrate is mentioned as an example of a counter substrate. In general, a color filter substrate is formed on a glass substrate by forming a black matrix in order to prevent unnecessary light leakage, and then patterning R (red), G (green), and B (blue) colored layers, and forming a protective film as necessary. It is formed. When using these board | substrates 13B, you may apply | coat and harden a transparent resin on the surface of the board | substrate 13B, and may form a planarization film.

The surface of the substrate 13B may be planarized as necessary. The planarization treatment is not particularly limited and can be carried out using a method known in the art. An example of the planarization treatment may be a method of forming a planarization film on the surface of the substrate 13B. For example, what is necessary is just to apply UV curable transparent resin etc. to the board | substrate 13B surface, and to UV-cure.

The polarizing plate 14A is provided on the side facing the backlight unit 12 or on the opposite side to the backlight unit 12 in the substrate 13A disposed on the backlight unit 12 side. The polarizing plate 14B is provided on the side opposite to the backlight unit 12 or on the side opposite to the backlight unit 12 in the substrate 13B located far from the backlight unit 12. These polarizing plates 14A and 14B are perpendicular to each other in the transmission axis direction. Here, the transmission axis direction of the polarizing plate 14A is set to the direction X orthogonal to the direction Y in the plane parallel to the substrate 13A, and the transmission axis direction of the polarizing plate 14B is the direction Y parallel to the substrate 13B. It is set. That is, the polarizing plate 14A and the polarizing plate 14B are arranged so that their transmission axis directions are perpendicular to each other, that is, orthogonal nicols.

The electrode layer 15 is provided on the substrate 13A. In this embodiment, the electrode layer 15 is provided on the opposite side to the backlight unit 12 in the substrate 13A on the backlight unit 12 side. The electrode layer 15 is formed by arranging a plurality of electrode lines 20A along the surface of the substrate 13A, and has a so-called comb-shaped electrode structure. Here, as shown in FIG. 3, each electrode line 20A is formed in linear form so that the long-axis direction may extend along the direction Y in the surface parallel to the surface of 13 A of board | substrates, for example. The electrode layers 15 are arranged at regular intervals along the direction X orthogonal to the direction Y in such a plane that the electrode lines 20A are parallel to the surface of the substrate 13A.

In the electrode layer 15 as shown in FIGS. 2 and 4, when a predetermined voltage is applied to each of the electrode lines 20A of the electrode layer 15, these mutually adjacent electrode lines (between the adjacent electrode lines 20A) are applied. 20A), the electric field E of the direction X parallel to the board | substrate 13A and the board | substrate 13B is produced | generated in this embodiment.

The weak anchoring alignment film 16 is formed on the opposite side to the backlight unit 12 in the substrate 13A on the backlight unit 12 side. The strong anchoring alignment film 17 is formed on the side opposite to the backlight unit 12 in the substrate 13B located far from the backlight unit 12.

The liquid crystal layer 18 is formed by filling a large number of liquid crystal molecules Lp between the weak anchoring alignment film 16 and the strong anchoring alignment film 17. In the liquid crystal layer 18, the alignment direction of the liquid crystal molecules Lp is driven by the electric field E generated by applying a voltage to each of the electrode lines 20A constituting the electrode layer 15. In this way, the alignment of the liquid crystal molecules Lp is changed, so that the liquid crystal layer 18 partially transmits or blocks the light supplied from the backlight unit 12 to generate a display image.

Here, the weak anchoring alignment layer 16 and the strong anchoring alignment layer 17 are different from each other in the alignment restraint force that restricts the alignment direction of the liquid crystal molecules Lp.

That is, as shown in FIG. 2, the weakly-anchored alignment layer 16 of the liquid crystal layer 18 has a weakly-anchored alignment layer 16 of the liquid crystal layer 18 when the applied voltage becomes higher than or equal to the threshold voltage when the electric field E is generated by applying the voltage. On the side, the liquid crystal molecules Lp deviate from the restraint of the weak anchoring alignment film 16. The alignment direction of the liquid crystal molecules Lp is changed from the initial alignment direction (direction Y in FIG. 2) in a plane parallel to the surfaces of the substrates 13A and 13B depending on the magnitude of the applied voltage.

On the other hand, in the strong anchoring alignment film 17, even if a voltage is applied to generate the electric field E, the liquid crystal molecules Lp at the strong anchoring alignment film 17 side in the liquid crystal layer 8 are arranged in the long axis direction of the substrate 13A, 13B) An initial alignment state substantially aligned with the in-plane orientation direction (direction Y in FIG. 2), that is, the initial alignment state along the alignment treatment direction (direction Y) of the weakly anchoring alignment film 16 is maintained.

As described above, when the electric field E is applied to the weak anchoring alignment layer 16 and the strong anchoring alignment layer 17, the alignment force of the weak anchoring alignment layer 16 of the liquid crystal layer 18 is removed from the alignment force of the weak anchoring alignment layer 16. While the alignment direction of the liquid crystal molecules Lp is changed, the alignment direction of the liquid crystal molecules Lp is maintained on the strong anchoring alignment film 17 side while being subjected to the alignment force by the strong anchoring alignment film 17.

As a result, in the liquid crystal layer 18, the orientation direction of the liquid crystal molecule Lp at the time of applying the electric field E more than a threshold value differs on the weak-anchoring alignment film 16 side and the strong-anchoring alignment film 17 side. As a result, the liquid crystal molecules Lp gradually increase in the amount of displacement of the alignment angle with respect to the initial alignment direction from the strong anchoring alignment film 17 side toward the weakly anchoring alignment film 16 side, and are transferred to the spirally twisted alignment state, and the electric field strength is lowered. When the predetermined value is reached, the liquid crystal molecules Lp near the weakly anchoring alignment layer 16 are aligned in a direction parallel to the electric field E direction. That is, it becomes the orientation state twisted 90 degrees toward the weak anchoring alignment film 16 side from the strong anchoring alignment film 17 side.

The liquid crystal layer 18 orientation state at the time of the said voltage application is the same as that of the liquid crystal orientation state at the time of voltage non-application in a TN system. Therefore, the optical design of the liquid crystal panel 11 is performed to satisfy ΔnP >> λ (Δn is the refractive index anisotropy of the liquid crystal, P is the helical pitch of the liquid crystal, λ is the wavelength of light), that is, the Mauginin Condition. When the lower liquid crystal layer 18 has a linear light effect, it becomes possible.

In addition, the following Gooch-Tarry equation (2) is known as a formula for imparting a light transmittance (T) in a TN type liquid crystal panel.

Equation 2

Here, u = dΔn / λπ / θ, d is a cell gap (thickness of the liquid crystal layer 18), θ is a twist angle of the liquid crystal molecules Lp, and in this embodiment, the weakly anchoring alignment layer 16 when voltage is applied. It corresponds to the angle difference of the orientation direction of the liquid crystal molecule of the () side and the liquid crystal molecule of the strong-anchoring alignment film 17 side. In addition, in this embodiment, since θ = π / 2, u = 2dΔn / λ.

In the liquid crystal panel 11, positive type liquid crystal molecules Lp are used, and the polarizing plate 14A and the polarizing plate 14B are arranged in orthogonal nicols whose transmission axis directions are perpendicular to each other, and the transmission axis direction of the polarizing plate 14B is an electric field. (E) It is set so that it may correspond with the orientation processing direction (direction Y in FIG. 1) with respect to the strong anchoring alignment film 17 for adjusting the orientation direction of the liquid crystal molecule (Lp) of an unapplied state. In the state in which the electric field E is not applied, the liquid crystal molecules Lp are oriented in the orientation processing direction with respect to the strong anchoring alignment layer 17 and are orthogonal to the transmission axis direction of the polarizing plate 14A, so that the backlight unit 12 Light from the side cannot penetrate through the polarizing plate 14A.

On the other hand, in the state in which the electric field E is applied, the liquid crystal molecules Lp have the long axis direction on the strong anchoring alignment film 17 side as described above in the alignment processing direction of the strong anchoring alignment film 17 (direction Y in FIG. 2). Maintain the initial orientation state along. On the other hand, on the weakly anchored alignment layer 16 side, the direction of orientation of the liquid crystal molecules Lp starts to change in a plane parallel to the substrate 13A by applying an electric field E of a threshold value or more, and the electric field strength is changed to a certain value. When reaching, the major axis direction of the liquid crystal molecules Lp follows the direction parallel to the electric field E, that is, the direction X parallel to the substrate 13A. At this time, the optical conditions of the liquid crystal panel 11 are designed to satisfy the mosquito condition and to have the maximum value of Equation (2), so that the linearly polarized light incident on the liquid crystal layer 18 maintains the polarization state while maintaining the polarization state. It rotates by 90 degrees (beams), passes through the polarizing plate 14B, and exits from the liquid crystal panel 11. Therefore, light incident on the liquid crystal panel 11 from the backlight unit 12 side can be transmitted with maximum efficiency. That is, the transmittance T at the time of voltage application of this embodiment can be made into the maximum (50% when the absorption of a polarizing plate is assumed to be 0). In general, since the response speed decreases when the cell gap d becomes large, it is preferable that the optical design of the liquid crystal panel selects a so-called first minimum condition from a plurality of conditions in which Equation (2) has a maximum value.

Thus, in the liquid crystal panel 11 of this embodiment, the polarizing plate 14A and the polarizing plate 14B are arrange | positioned by orthogonal nicotine using positive liquid crystal molecule Lp, and the transmission axis direction of the polarizing plate 14B is the electric field ( E) It is set so that it may coincide with the orientation process direction with respect to the strong anchoring alignment film 17 for adjusting the orientation direction of liquid crystal molecule (Lp) in an unapplied state (direction Y in FIG. 1). According to such a configuration, when a predetermined electric field E having a threshold value or more is applied to the liquid crystal panel 11, the liquid crystal molecules Lp move from the strong anchoring alignment layer 17 side toward the weakly anchoring alignment layer 16 side, and the initial alignment direction. The amount of displacement in the orientation direction with respect to gradually increases, and is transferred to the spirally twisted alignment state. As a result, the light passing through the polarizing plate 14A from the backlight unit 12 side changes the polarization plane along the alignment direction distribution of the liquid crystal molecules Lp from the weak anchoring alignment layer 16 side toward the strong anchoring alignment layer 17 side. It exits through the opposite polarizing plate 14B.

As described above, the liquid crystal panel 11 adopts the IPS driving method for displacing the liquid crystal molecules Lp in the plane along the surfaces of the substrates 13A and 13B as the liquid crystal driving method, and performs light on / off control using the optical fiber. do.

By the way, the above-mentioned strong anchoring alignment film 17 is formed as follows, for example. First, an alignment film made of polyimide or the like is formed on the substrate 13B. Thereafter, the roller wound with a cloth made of rayon and cotton is rotated while maintaining the rotation speed and the distance between the roller and the substrate 13B, and the surface of the alignment film is rubbed in a predetermined direction (rubbing method) or irradiated with polarized ultraviolet rays. Thus, anisotropy is generated on the surface of the alignment film made of polyimide (photoalignment method). The strong anchoring alignment film 17 whose orientation direction is set by these rubbing methods, the photo-alignment method, etc. gives a strong orientation forcing force to the liquid crystal molecules Lp than the weakly anchoring alignment film 16.

The weak anchoring alignment film 16 is formed of a bottle brush. Bottle brush is a kind of comb polymer that has side chains (branches) combined from several different points of the main chain (stem), especially when the branch density (graft density, segment density) of the side chain is high, bottle brush, molecular bottle brush It is called a molecular bottlebrush or a cylindrical polymer brush. It is known that the bottle brush has a rod-shaped cylindrical shape in which the main chain is extended by the exclusion volume effect of the side chain. Its name is denominated in that it resembles the brush shape used for cleaning bottles and flasks. Synthesis of the bottle brush includes a Grafting-to method of introducing a side chain into a stem polymer, a Grafting-from method of polymerizing a monomer from a macro initiator (a stem polymer having a polymerization active point), and a macromonomer (having a polymerizable functional group at a fragment end). Polymer) is largely classified into a grafting-through method of polymerization. It is known that bottle brushes have the same properties (rich brush effect) as rich polymer brushes.

An example of the chemical structure of a bottle brush is shown below.

Formula 1

The main chain and the side chain are segments containing at least one monomer unit selected from the group consisting of (meth) acrylate monomers, (meth) acrylamide monomers and styrene monomers. For example, in Formula 1, R ₁ : -H or -CH ₃ , R ₂ : -H or-(C = 0) -C (CH ₃ ) ₂ -Z (Z is halogen), R ₃ : -H or- CH ₃ , R ₄ :-(C = O) -OR (R: alkyl group etc.), R ₅ : -H or -CH ₃ , R ₆ :-(C = O) -OR (R: alkyl group including a crosslinking group Etc.) can be mentioned. The subscript l ₁ is the number of repeating units having a side chain polymer, l ₂ is the number of repeating units without a side chain polymer, and m is a side chain polymer having affinity with a liquid crystal, a low glass transition point, and dissolving in a coating solvent, as described below. The repeating unit number, n represents the repeating unit number of the side chain polymer which forms chemical crosslink as mentioned later. The sum of l ₁ and l ₂ is comparable to the degree of polymerization of the entire main chain.

As a main chain, the segment containing the monomer which can introduce | transduce a polymerization initiator by the grafting-from method is preferable. For example, hydroxyl group containing (meth) acrylate, such as 2-hydroxyethyl (meth) acrylate, etc. are mentioned.

As a side chain, the segment which has affinity with a liquid crystal, low glass transition point, and has a monomer which can melt | dissolve in a coating solvent is preferable. For example, glycol ethers such as (meth) acrylate having a alkyl such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate or polyethylene glycol mono (meth) acrylate ( Meth) acrylate, etc. are mentioned.

It is preferable that a side chain has the segment containing the monomer which forms chemical crosslinking. For example, monomers, such as a trimethoxysilyl group, a triethoxysilyl group, and the silicon atom containing (meth) acrylate which has a dimethyl silicone chain, can also be used. In this case, the bottle brush may be regarded as a core-shell type, the core is a segment having affinity with the liquid crystal, a low glass transition point, and a monomer having a solvent soluble in the coating solvent, and the shell containing a monomer which forms a chemical crosslink. Point to. Chemical crosslinking reaction proceeds by heat, light, moisture, and the like.

The bottle brush can be obtained by using a known living polymerization, but is more preferably synthesized by a living radical polymerization method. Living radical polymerization refers to a polymerization reaction in which the chain transfer reaction and the stop reaction do not substantially occur in the radical polymerization reaction, and the chain growth terminal maintains the activity even after the monomer has finished the reaction. In this polymerization reaction, the polymerization activity is maintained at the terminal of the produced polymer even after the completion of the polymerization reaction, and the polymerization reaction can be started again by adding a monomer.

As a characteristic of living radical polymerization, it is possible to synthesize a polymer having an arbitrary average molecular weight by controlling the monomer and the polymerization initiator concentration ratio, a point where the molecular weight distribution of the resulting polymer is very narrow, and applicable to the block copolymer synthesis. The point etc. are mentioned. In addition, living radical polymerization may be called "controlled radical polymerization" when it is omitted by "LRP".

In the polymerization method of the present invention, a radical polymerizable monomer is used as the monomer. A radically polymerizable monomer means the monomer which has an unsaturated bond which can perform radical polymerization in presence of organic radical. Such unsaturated bonds may be double bonds or triple bonds. That is, in the polymerization method of the present invention, any monomer conventionally known to perform living radical polymerization can be used.

As a living radical polymerization method, various methods, specifically, listed below are reported. For example, the nitroxide method using dissociation and bonding of nitroxy radicals (hereinafter abbreviated as NMP method) is used, and heavy metals such as copper, ruthenium, nickel and iron, and ligands forming complexes thereof. Atom transfer radical polymerization (Atom Transfer Radical Polymerization, hereinafter referred to as ATRP method), dithiocarboxylic acid ester and the like which polymerize a halogen compound as an initiator compound are polymerized using an addition polymerizable monomer and a radical initiator as an initiator compound. Using heavy metal compounds such as reversible addition fragmentation chain transfer polymerization (hereinafter referred to as RAFT method), organic tellurium and organic bismas, organic antimony, antimony halide, organic germanium, and germanium halide. Degenerative transfer or the following DT method is omitted) Wide research and development have been made.

It is also preferable that the side chain has a segment containing a monomer to form a physical crosslink. For example, a block such as the phase separation of the core and the shell of the bottle brush is possible. As an example, the use of a segment comprising methyl methacrylate as a core and a segment comprising styrene as a shell causes spontaneous phase separation and physical crosslinking after film formation.

5 is a cross-sectional view showing an example of a bottle brush formed on a substrate as a weak anchoring alignment film. The bottle brush 2 is formed by apply | coating the bottle brush polymer previously manufactured by the living radical polymerization method to 13 A of board | substrates. As described above, the bottle brush 2 is a kind of comb-tooth type polymer in which the graft side chain 4 is bonded to the main chain 3, and a plurality of bottles are formed by combining the graft side chains 4 of the bottle brush 2 with each other. Brushes 2 are coupled to each other. And a certain number of bottle brushes 2 are fixed by covalent bonding to the surface of the substrate 13A by the graft side chain 4, and the remaining bottle brushes 2 extend in the opposite direction from the surface of the substrate 13A. . Tg (our transition temperature) of the bottle brush 2 is -5 degrees C or less.

As shown in FIG. 5, the liquid crystal molecules Lp penetrate into a portion away from the substrate 13A in the graft side chain 4 of the bottle brush 2 formed on the substrate 13A, and the liquid crystal molecules Lp. The side chain 4 of the bottle brush 2 in contact with is swollen (swelled state is not shown in the drawing).

In the present specification, the portion of the bottle brush 2 in which the liquid crystal molecules Lp penetrates is shown as the coexistence portion 5, and the portion of the bottle brush 2 in which the liquid crystal molecules Lp does not penetrate is used as the bottle brush layer 6. Indicates. In addition, although the coexistence part 5 and the bottle brush layer 6 were clearly distinguished and shown in FIG. 5 from the viewpoint which makes this invention easy to understand, in reality, the boundary of the coexistence part 5 and the bottle brush layer 6 is distinguished. It's hard to do

By using the bottle brush 2 as described above, since the Tg (glass transition temperature) of the coexistence portion 5 becomes a temperature considerably lower than the normal temperature, the shape of the coexistence portion 5 can be freely varied at room temperature. Therefore, the state of the coexistence portion 5 is changed at the interface between the coexistence portion 5 and the liquid crystal molecules Lp, and the liquid crystal molecules Lp are aligned in the horizontal direction with respect to the substrate 13A, and in any direction in the plane. A state (zero plane anchoring state) having no orientation forcing can be realized.

Since the Tg of the coexistence part 5 differs according to the kind of the bottle brush 2 and liquid crystal molecules Lp to be used, it cannot be defined uniquely, but generally compared with Tg of the bottle brush 2 alone. Lowers. In addition, Tg of the coexistence part 5 changes with the degree of penetration of the liquid crystal molecule Lp with respect to the bottle brush 2 (namely, the ratio of the bottle brush 2 and liquid crystal molecule Lp). Specifically, the coexistence portion 5 on the side of the liquid crystal molecules Lp having a large proportion of the liquid crystal molecules Lp in the coexistence portion 5 has a low Tg and a bottle brush layer 6 having a small ratio of the liquid crystal molecules Lp. The coexistence part 5 of a side becomes high in Tg.

However, by using the bottle brush 2 having a Tg of -5 ° C or lower, the Tg of the coexistence portion 5 can be made sufficiently lower than normal temperature, so that the surface is horizontal with respect to the surface of the substrate 13A at normal temperature. The orientation control of the liquid crystal molecule Lp in the inside can realize the state (zero surface anchoring state) which does not have orientation forcing in any direction in surface.

The bottle brush 2 forms a layer of the bottle brush 2 on the substrate 13A surface. Although the thickness of the bottle brush 2 layer is not particularly limited, it is generally tens of nm, specifically 1 nm or more and less than 100 nm, preferably 10 nm to 80 nm. The bottle brush 2 layer also has a size exclusion effect, so that a certain size of material cannot pass through the bottle brush 2 layer. Therefore, even if the thickness of the bottle brush 2 layer is made thin, it is possible to prevent impurities from entering the liquid crystal molecules Lp from the substrate 13A side.

The bottle brush 2 is formed by apply | coating the bottle brush polymer previously manufactured by the living radical polymerization method to 13 A of board | substrates, for example. Here, the term 'living radical polymerization' means that the radical growth reaction does not substantially cause the chain transfer reaction and the stop reaction in the radical polymerization reaction, and the chain growth terminal maintains the activity even after the radical polymerizable monomer has completed the reaction. It means a polymerization reaction.

In addition, formation of a bottle brush polymer is performed according to the following procedures.

1. Manufacture of main chain polymer (poly (2-hydroxyethyl methacrylate), PHEMA)

2. Introduction of the polymerization initiator into the main chain polymer (PHEMA)

3. bottle brush polymer manufacturer

Substrate 13A application of the bottle brush polymer is performed using existing equipment such as flexographic printing, inkjet printing or die coating. Thereafter, by heating the substrate 13A to a suitable temperature, the bottle brush polymer is crosslinked, and the bottle brush 2 is formed.

The bottle brush 2 may be formed on the surface of the substrate 13A via an immobilization film, if necessary, from the viewpoint of increasing the adhesion between the substrate 13A and the bottle brush 2. The immobilization film is not particularly limited as long as it is excellent in adhesion to the substrate 13A and the bottle brush 2, and those generally known in living radical polymerization can be used. As an example of an immobilization film, the film formed from the alkoxysilane compound represented by following General formula (2) is mentioned.

Formula 2

In general formula (2), each R ¹ is independently an alkyl group, preferably a methyl group or an ethyl group, of C ¹ to C 3, R ² is each independently a methyl group or an ethyl group, X is a halogen atom, preferably Br, n Is an integer of 3-10, More preferably, it is an integer of 4-8.

It is preferable that the bottle brush 2 is covalently bonded to the fixed film. When the immobilization film and the bottle brush 2 are coupled by covalent bonds with strong bonding force, the peeling of the bottle brush 2 can be sufficiently prevented. As a result, the possibility that the characteristic of the liquid crystal panel 11 will fall becomes low, and the reliability of the liquid crystal panel 11 improves.

The formation method of an immobilization film is not specifically limited, What is necessary is just to set suitably according to the material to be used. For example, the immobilization film can be formed by immersing the substrate 13A in the solution for forming the immobilization film or applying the solution for forming the immobilization film to the substrate 13A and then drying it. In order to form an immobilization film in a predetermined part here, you may mask to the part which does not form an immobilization film. In addition, you may wash | clean the board | substrate 13A before formation of a fixed film as needed.

The method of injecting the liquid crystal molecules Lp between the substrate 13A on which the bottle brush 2 is formed and the substrate 13B is not particularly limited, and the vacuum injection method using the capillary phenomenon and the liquid crystal drop injection method (ODF: One Drop) are not particularly limited. Filling) can be used. For example, in the case of using a vacuum injection method using a capillary phenomenon, it may be performed as follows.

First, the electrode layer 15 is formed on the one substrate 13A by a known method, and then the bottle brush 2 is formed. On the other substrate 13B, a spacer is formed by a well-known method, such as photolithography. Next, after washing and drying one board | substrate 13A, a sealing material is apply | coated, it overlaps with the other board | substrate 13B, hardens and seals a sealing material by heating, UV irradiation, etc. Here, it is necessary to open the injection hole for injecting the liquid crystal molecules (Lp) to a part of the sealing material. Next, liquid crystal molecules Lp are injected from the injection hole between the substrates 13A and 13B by vacuum injection, and then the injection hole is sealed.

The liquid crystal molecules Lp used in the present invention are not particularly limited, and those known in the art can be used. Especially, as liquid crystal molecule Lp, it is preferable that NI point (phase transition temperature from N phase to I phase) of liquid crystal molecule Lp is higher than Tg of coexistence part 5.

As described above, according to the liquid crystal panel 11, the strong anchoring disposed to face the gap between the backlight unit 12, the substrate 13A on which the weak anchoring alignment layer 16 is formed, and the weak anchoring alignment layer 16. A liquid crystal layer 18 disposed between the substrate 13B on which the alignment layer 17 is formed, the weak anchoring alignment layer 16 and the strong anchoring alignment layer 17, and the liquid crystal molecules Lp are driven to transmit or block light; An electrode layer 15 is provided on the substrate 13A and applies an electric field E to the liquid crystal molecules Lp. Furthermore, when the weak anchoring alignment film 16 is applied with the electric field E, the restraining force that restricts the alignment direction of the liquid crystal molecules Lp is smaller than that of the strong anchoring alignment film 17.

In the state where the electric field E is applied, the displacement angle of the liquid crystal layer Lp alignment direction of the liquid crystal layer 18 gradually increases from the strong anchoring alignment film 17 side toward the weakly anchoring alignment film 16 side.

Thus, when a predetermined voltage sufficient to change the alignment direction of the liquid crystal molecules Lp on the weakly anchoring alignment layer 16 side is applied, the liquid crystal layer 18 of the liquid crystal panel 11 may be driven to perform display. Therefore, the liquid crystal molecules can be driven at a low voltage.

In addition, according to the above configuration, the liquid crystal molecules Lp are driven by using the opticality of the liquid crystal molecules Lp. According to such a configuration, since light changes and transmits along the alignment of the liquid crystal molecules Lp, it is possible to perform display with high transmittance.

By using the bottle brush 2 as described above, since the Tg (glass transition temperature) of the coexistence portion 5 becomes a temperature considerably lower than the normal temperature, the shape of the coexistence portion 5 can be freely varied at room temperature. Therefore, the state of the coexistence portion 5 is changed at the interface between the coexistence portion 5 and the liquid crystal molecules Lp, and the liquid crystal molecules Lp are aligned in the horizontal direction with respect to the substrate 13A, and in any direction in the plane. A state (zero plane anchoring state) having no orientation forcing can be realized.

In order to stably realize the weak anchoring state (zero plane anchoring state), it is necessary to use a high compatibility with the liquid crystal and strongly adhered to the substrate as the alignment film. It is also necessary to cover the interface so densely that the liquid crystal does not come into contact with the substrate. Therefore, in order to form a conventional polymer brush on a substrate, it is necessary to immerse the substrate in a polymerization liquid and polymerize at a high temperature for several hours. On the other hand, in the present invention, since the bottle brush 2 can be fixed on the substrate by dissolving the bottle brush 2 in an organic solvent and applying the solution to the substrate, the bottle brush can be fixed on the substrate. In addition, it becomes possible to form at low cost.

The problem at the time of forming a weak-anchoring alignment film with a conventional polymer brush is as follows.

(1) In order to produce a weak anchoring alignment film using a polymer brush, since a monomer is reacted and grown in order from the surface of the substrate, a simple method such as a coating method cannot be performed, and the substrate needs to be immersed in the polymerization liquid. Only area substrates can be manufactured.

(2) Since a living radical polymerization reaction is used for polymer brush synthesis, a reaction time is required for a long time, for example, 24 to 48 hours.

(3) A polymer brush is not produced by the simple method of heating and superposing | polymerizing after apply | coating.

(4) The acrylic resin is dissolved because the polymerization solution is an aromatic strong solvent.

On the other hand, the advantage in the case of forming a weak-anchoring alignment film with a bottle brush is as follows.

(1) Since an LCD panel can be manufactured by the process of applying a bottle brush after manufacturing it in another place, it is not necessary to carry a large polymerization container into an LCD manufacturing line. Therefore, it can respond to the large board | substrate of 1 m-2 m square.

(2) Since the weak anchoring alignment film can be produced only by applying and firing the bottle brush, the time required for preparing the alignment film is short, and the production efficiency of the LCD panel is good.

(3) Since the bottle brush can be applied to the substrate by flexographic printing, inkjet printing, or die coating, the current alignment film production process (polyimide forming process) can be used, and thus no new facility investment is required.

(4) Since there is no process of heating in the polymerization liquid, the weakly anchoring alignment film can also be produced on resin members such as color filters and column spacers. Moreover, it is also possible to form on a plastic board.

<2nd embodiment>

Next, 2nd Embodiment of the liquid crystal display element which concerns on this invention is described. In addition, in 2nd Embodiment described below, about the structure common to said 1st Embodiment, the same code | symbol is attached | subjected in drawing, and the description is abbreviate | omitted. In 2nd Embodiment, the electrode layer 15 similar to the said 1st Embodiment is provided, and negative type liquid crystal molecule Ln is driven.

6 is a cross-sectional view showing a schematic configuration of a liquid crystal display shown as the second embodiment. FIG. 7 is a diagram showing a liquid crystal molecular alignment direction distribution in a state where an electric field is applied using a liquid crystal having a negative dielectric anisotropy in the liquid crystal panel of the liquid crystal display shown as the second embodiment. FIG. 8 is a diagram showing a relationship between an electrode line and a liquid crystal molecular alignment direction in a liquid crystal panel of the liquid crystal display shown as the second embodiment, in which a liquid crystal having a dielectric constant anisotropy is used and an electric field is not applied. FIG. 9 is a diagram showing a relationship between an electrode line in a state where an electric field is applied using a liquid crystal having a negative dielectric anisotropy and a liquid crystal molecular alignment direction in the liquid crystal panel of the liquid crystal display shown as the second embodiment.

6 and 7, in this embodiment, the polarizing plate 14A and the polarizing plate 14B are arranged in orthogonal nico, and the transmission axis direction of the polarizing plate 14A is set along the direction Y, and the other polarizing plate 14B ) Is set to follow the direction X.

The electrode layer 15 is formed by arranging a plurality of electrode lines 20A along the surface of the substrate 13A. As shown in FIGS. 12 and 13, each electrode line 20A is formed in a straight line such that its major axis direction extends along the direction Y in a plane parallel to the surface of the substrate 13A, for example. The electrode layers 15 are arranged at regular intervals along the direction X orthogonal to the direction Y in such a plane that the electrode lines 20A are parallel to the surface of the substrate 13A.

The liquid crystal molecules Ln of the liquid crystal layer 18 have negative dielectric anisotropy, have a small dielectric property in the long axis direction, and are large in a direction perpendicular to the long axis direction. As shown in FIGS. 6 and 8, when the negative liquid crystal molecules Ln are used, the alignment processing direction of the strong anchoring alignment layer 17 for adjusting the alignment direction of the liquid crystal molecules Ln in the state in which the electric field E is not applied. Is a direction perpendicular to the major axis direction of each electrode line 20A (direction X in FIG. 8). In addition, the polarizing plate 14A and the polarizing plate 14B are arranged in orthogonal nico, and the strong-anchoring alignment layer 17 for adjusting the alignment direction of the liquid crystal molecules (Ln) in the state where the transmission axis direction of the polarizing plate 14A is not applied to the electric field E is applied. ) Is set so as not to coincide with the orientation processing direction with respect to (). Then, in the state in which the electric field E is not applied, the light from the backlight unit 12 side does not transmit.

As shown in FIG. 7, even when the negative liquid crystal molecules Ln are applied to the electric field E, the initial alignment state (direction) in which the major axis direction is along the alignment treatment direction of the strong anchoring alignment film 17 is applied. Maintain X). On the other hand, when the orientation angle of the liquid crystal molecules Ln is displaced in a plane parallel to the substrate 13A by the applied electric field E on the weakly anchoring alignment film 16 side, the electric field strength reaches a certain value. The major axis direction follows the direction orthogonal to the electric field E, that is, the direction Y parallel to the substrate 13A. Thus, in the state which applied the electric field E, the displacement angle of the liquid-crystal molecule (Ln) alignment direction of the liquid crystal layer 18 gradually increases from the strong anchoring alignment film 17 side toward the weakly anchoring alignment film 16 side. When an electric field of a predetermined value or more is applied, the alignment direction (direction Y) of the liquid crystal molecules Ln on the weakly anchoring alignment film 16 side becomes a direction orthogonal to the electric field E, and coincides with the transmission axis direction of the polarizing plate 14A. Therefore, the light passing through the polarizing plate 14A from the backlight unit 12 side changes in the polarization plane along the liquid crystal molecule Ln alignment direction distribution, and is emitted through the opposite polarizing plate 14B.

Thus, in the liquid crystal panel 11 of this embodiment using the liquid crystal whose dielectric anisotropy is negative also, it becomes possible to perform display with higher transmittance while driving liquid crystal molecule Ln at low voltage.

In the first to second embodiments, a so-called normaly black liquid crystal panel 11 that has a dark display when no voltage is applied and a light that is bright when a voltage is applied is described.

Third Embodiment

Next, 3rd Embodiment of the liquid crystal display element which concerns on this invention is described. In addition, in 3rd Embodiment described below, about the structure common to said each embodiment, the same code | symbol is attached | subjected in drawing and the description is abbreviate | omitted. In 3rd Embodiment, the transmission axis direction of 14 A of polarizing plates differs with respect to the said 1st Embodiment.

FIG. 10 is a sectional view showing a schematic configuration of a liquid crystal display shown as the third embodiment. FIG.

FIG. 11 is a diagram showing the liquid crystal molecule alignment direction distribution in a liquid crystal panel of the liquid crystal display shown as the third embodiment using a liquid crystal having a constant dielectric anisotropy and applying an electric field. In 1st Embodiment, although the transmission axis direction of 14 A of polarizing plates was direction X, in this 3rd Embodiment, it is set to direction Y. In FIG. As a result, the polarizing plates 14A and 14B are arranged so that their transmission axis directions are parallel to each other, that is, parallel Nicols.

In such a configuration, in the non-applied state of the electric field E, the light passing through the polarizing plate 14A from the backlight unit 12 side from the liquid crystal panel 11 is maintained while maintaining the polarization state and the polarization plane as shown in FIG. 10. It is emitted. At this time, since the polarization direction (direction Y) of linearly polarized light incident on the liquid crystal layer 18 and the transmission axis direction (direction Y) of the polarizing plate 14B coincide, most of the light from the backlight unit 12 side is It can pass through the polarizing plate 14B.

On the other hand, when a predetermined electric field E having a threshold value or more is applied to the liquid crystal panel 11 as shown in FIG. 11, the long axis direction is initially set along the alignment processing direction of the strong anchoring alignment film 17 on the strong anchoring alignment film 17 side. As the size of the applied electric field E increases while the alignment state (direction Y) is maintained, the amount of displacement in the alignment direction with respect to the initial alignment direction of the liquid crystal molecules Lp near the weak anchoring alignment film 16 gradually increases. When the intensity of the applied electric field E reaches a certain value, the alignment direction of the liquid crystal molecules Lp on the side of the weakly anchoring alignment film 16 becomes a direction parallel to the electric field E (direction X) and the polarizing plate 14A. Orthogonal to the transmission axis direction, light from the backlight unit 12 side cannot pass through the polarizing plate 14A.

By arranging the polarizing plates 14A and 14B in such a manner as to be parallel nicols, the so-called normaly black liquid crystal panel 11 which displays dark when no voltage is applied and bright when voltage is applied, as described in the first to second embodiments, is described. Unlike the above, the liquid crystal panel 11 can be configured in a so-called normaly white type, in which the display is bright when no voltage is applied and dark when the voltage is applied.

Fourth Embodiment

Next, 4th Embodiment of the liquid crystal display element which concerns on this invention is described. In addition, in 4th Embodiment described below, about the structure common to said each embodiment, the same code | symbol is attached | subjected in drawing and the description is abbreviate | omitted. In 4th Embodiment, the transmission axis direction of 14 A of polarizing plates is different from the said 2nd Embodiment.

It is sectional drawing which shows schematic structure of the liquid crystal display shown as 4th Embodiment.

It is a figure which shows the liquid-crystal molecular orientation direction distribution in the liquid crystal panel of the liquid crystal display shown as said 4th embodiment, using the liquid crystal whose dielectric constant anisotropy is negative, and applying the electric field. In 2nd Embodiment, although the transmission axis direction of 14A of polarizing plates was direction Y, it is set to direction X in this 4th Embodiment. As a result, the polarizing plates 14A and 14B are arranged so that their transmission axis directions are parallel to each other, that is, parallel Nicols.

In such a configuration, in the non-applied state of the electric field E, the light passing through the polarizing plate 14A from the backlight unit 12 side is discharged from the liquid crystal panel 11 while maintaining the polarization state and the polarization plane as shown in FIG. 12. It is emitted. At this time, since the polarization direction (direction X) of the linearly polarized light incident on the liquid crystal layer 18 and the transmission axis direction (direction X) of the polarizing plate 14B coincide, most of the light from the backlight unit 12 side is It can pass through the polarizing plate 14B.

On the other hand, when a predetermined electric field E having a threshold value or more is applied to the liquid crystal panel 11 as shown in FIG. 13, the long axis direction is initially determined by the alignment processing direction of the strong anchoring alignment film 17 on the side of the strong anchoring alignment film 17. As the magnitude of the applied electric field E increases while the alignment state (direction X) is maintained, the amount of displacement in the alignment direction with respect to the initial alignment direction of the liquid crystal molecules Lp near the weakly anchoring alignment film 16 gradually increases. When the intensity of the applied electric field E reaches a certain value, the alignment direction of the liquid crystal molecules Ln on the side of the weakly anchoring alignment film 16 becomes a direction (direction Y) orthogonal to the electric field E and the polarizing plate 14A. Orthogonal to the transmission axis direction, light from the backlight unit 12 side cannot pass through the polarizing plate 14A.

Thus, in this 4th Embodiment, it is comprised by normaly white type similarly to the said 3rd Embodiment.

As mentioned above, although preferred embodiment of this invention was described in detail, various deformation | transformation and equal embodiment are possible for those skilled in the art in the future.

Therefore, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the claims are included in the present invention.

For example, in this embodiment, although the weak anchoring alignment film 16 was arrange | positioned at the backlight unit 12 side, the strong anchoring alignment film 17 was arrange | positioned at the side separated from the backlight unit 12, It is not limited to this. The weak anchoring alignment film 16 may be disposed on the side separated from the backlight unit 12, and the strong anchoring alignment film 17 may be disposed on the backlight unit 12 side. The electrode layer 15 is not limited to the side separated from the backlight unit 12 but may be disposed on the opposite side thereof.

That is, the strong anchoring alignment layer 17 is formed by performing a rubbing process after forming a polyimide layer on the substrate 13A provided with the electrode layer 15. On the other hand, a bottle brush layer is formed on the substrate 13B, and the weak anchoring alignment layer 16 is formed. As described above, the anchoring value of the bottle bristle layer is smaller than the anchoring value of the polyimide layer. Thereafter, the liquid crystal panel 11 may be manufactured by bonding the substrate 13A and the substrate 13B together with a sealing agent and injecting the liquid crystal therein.

Furthermore, in the first to second embodiments, the liquid crystal molecules L are aligned with respect to the initial alignment direction from the strong anchoring alignment layer 17 side toward the weakly anchoring alignment layer 16 side with the electric field E applied thereto. The amount of displacement of gradually becomes large, and it becomes the orientation state twisted spirally. Herein, the liquid crystal molecules L have a maximum amount of the angular displacement of the liquid crystal molecules L in the middle portion between the strong and low alignment layers 17 and the weak anchoring alignment layer 16, and the weakly anchoring alignment layer 16 is larger than the portions thereof. The amount of orientation angle displacement of the liquid crystal molecules L may be the same (maximum state) over. In other words, the liquid crystal molecules L are arranged helically in the region from the strong anchoring alignment layer 17 side to the middle portion of the strong anchoring alignment layer 17 and the weak anchoring alignment layer 16 in the state where the electric field E is applied, In the area | region from the intermediate part of the strong anchoring alignment film 17 and the weak anchoring alignment film 16 to the weakly anchoring alignment film 16 side, it may be arrange | positioned similarly.

<Example>

Since the experimental experiment was performed about the structure shown in this embodiment using the liquid crystal panel modeled as follows, the result is shown below.

<LCD panel making>

A substrate (hereinafter referred to as an electrode substrate) on which an ITO comb-shaped electrode (thickness: about 55 nm, electrode width (L) / inter-electrode distance (S) = 4 μm / 10 μm) and a photospacer (hereinafter referred to as an electrode substrate) are formed. And a counter substrate) were bonded together, and the liquid crystal panel which filled the liquid crystal in the space | gap was produced. A bottle brush was formed as an alignment film on the electrode substrate of the liquid crystal cell of the Example. The formation method of a bottle brush is as follows.

<Bottle brush formation method>

The methacrylate polymer which has a living radical polymerization initiator in the side chain was used as a macro initiator. Macro initiator was polymethyl methacrylate conversion, Mn (number average molecular weight) was 50000, PDI (molecular weight distribution) was 1.4, and main chain polymerization degree 1 was 200. Bottle brush in which hexyl methacrylate (hereinafter abbreviated as HMA) and 3-methacryloxypropyltrimethoxysilane (hereinafter abbreviated as MOPS) are introduced into the side chain by using the living radical polymerization described above. Got. When molecular weight was measured by GPC by THF solvent, Mn was 230000 and PDI was 2.0 in polymethylmethacrylate conversion. The repeating unit number of HMA and MOPS was m = 30 and n = 0.1 as an average value, respectively.

<Bottle brush polymer coating>

0.1 mass part of bottle brush polymer was melt | dissolved in THF, and 2.1 g (5 wt% of bottle brush polymer) of THF solution was obtained. The solution was spin-coated on the glass substrate with an electrode (rotation speed 3000 rpm, 60 second). Then, the spin coating film was bridge | crosslinked by leaving a board | substrate at 120 degreeC under vacuum conditions for 3 hours. Furthermore, the crosslinked spin coating film was ultrasonically cleaned with THF.

On the other hand, a photo spacer having a height of 3.0 mu m was formed on the opposing substrate side of the liquid crystal panel of the example, and then PI (JALS-16470 made by JSR) was coated as an alignment film. The rubbing process was given to the PI alignment film surface. The rubbing treatment was performed such that when the electrode substrate and the counter substrate were bonded together, the rubbing direction of the counter substrate and the comb-tooth shaped electrodes were perpendicular to each other. The electrode substrate and the counter substrate were bonded together through a sealing material, and a blank cell was produced through a sealing hardening treatment at 120 ° C. × 2 hours under a nitrogen atmosphere while pressing. Thereafter, the negative liquid crystal was injected into the empty cell by the vacuum injection method, and then the injection hole was sealed with a UV curable encapsulant. And the counter substrate was arrange | positioned above the electrode substrate below (backlight side).

In addition, the negative liquid crystal used the Merck company product, and the physical-property value was as follows.

Tni (nematic phase-isotropic transition temperature): 79.5 ° C

Δn (refractive anisotropy): 0.1176 [589 nm, 20 ° C.]

Δε (dielectric anisotropy): -3.1 [1 kHz, 20 ° C]]

ε⊥: 6.5

K1: 15.1 [pN, 20 ° C.]

K3: 14.7 [pN, 20 ° C]

γ1 (rotational viscosity): 121 [mPas, 20 ° C]

This liquid crystal corresponds to the liquid crystal mixture described in Example 22 (Table 45) of Unexamined-Japanese-Patent No. 2016-094622, for example.

Comparative Example

The manufacturing procedure of the liquid crystal panel of a comparative example is as follows. A substrate (hereinafter referred to as an electrode substrate) on which an ITO comb-shaped electrode (thickness: about 55 nm, electrode width L / electrode distance S = 4 μm / 10 μm) is formed, and a substrate on which a photo spacer is formed (hereinafter referred to as an opposing substrate) And the liquid crystal panel in which the liquid crystal was filled in the space | gap was produced.

On the liquid crystal panel electrode substrate of the comparative example, the PHMA brush was polymerized as an orientation film. PHMA brush polymerization was performed by surface initiated ATRP (atomic transfer radical polymerization). First, the substrate was ultrasonically cleaned with acetone and chloroform for 15 minutes, and then nitrogen gas was blown to dry, and then UV-O ₃ treatment was performed for 15 minutes. At this stage, the area | region (part of sealing material) which does not form a polymer brush was protected by masking tape.

Next, a starting material: 2-brobo-2-methyl-N- (3- (triethoxysilyl) propyl) propaneamide (BPA): 0.05 g, ethanol: 4.7 g, aqueous ammonia: 0.25 g was mixed into a solution. It immersed overnight in the state which shielded the board | substrate, and fixed the starting material to the board | substrate surface. Thereafter, the substrate was ultrasonically cleaned with acetone for 10 minutes and then dried by blowing nitrogen gas. The PHMA brush is a polymer solution (monomer: hexyl methacrylate, HMA / 29.74 g / 174.7 mmol) on which a BPA-immobilized substrate is subjected to freezing and degassing, and an initiator: ethyl-2-bromoisobutyrate , EBIB / 68.7 mg / 0.35 mmol, catalyst: CuBr / 152.2 mg / 1.06 mmol, ligand: N, N, N ', N' ', N' '-pentamethyldiethylenetriamine, PMDETA / 243.8 mg / 1.41 mmol , Solvent: anisole / 29.97 g / 277 mmol) and polymerized by heating at 70 ° C. for 7 hours.

As a result of measuring the prepolymer in the same patch by gel permeation chromatography, the molecular weight and molecular weight distribution of the polymerized PHMA brush were estimated to be Mn = 88900 and Mw / Mn = 1.74, respectively. The film thickness (h) of the PHMA brush was determined to be 18.0 nm based on the X-ray reflectivity measurement (Ultima IV, manufactured by Rigaku). The graft density (σ) of the PHMA brush is also the σ = ρhN _A / M (ρ: bulk polymer density) under the assumption that the polymer brush density is equal to the bulk polymer density (1.00 g / cm ³ is used as the PHMA density). , h: polymer brush film thickness, N _A : avogadro constant, M: polymer brush molecular weight), and was estimated to be 0.12 chains / nm ² .

On the other hand, after forming the photo spacer of 3.0 micrometers in height on the opposing board | substrate side of the liquid crystal panel of a comparative example, PI (JALS-16470 made from JSR) was coated as an orientation film. The rubbing process was given to the PI alignment film surface. The rubbing treatment was performed such that when the electrode substrate and the counter substrate were bonded together, the rubbing direction of the counter substrate and the comb-tooth shaped electrodes were perpendicular to each other. The electrode substrate and the counter substrate were bonded to each other via a sealing material, and a blank cell was produced through a sealing hardening treatment at 120 ° C. × 2 hours under a nitrogen atmosphere while being pressurized. Thereafter, the negative liquid crystal was injected into the empty cell by the vacuum injection method, and then the injection port was sealed with a UV curable encapsulant. In addition, the liquid crystal used the same negative liquid crystal as used in the Example also in the comparative example. And the counter substrate was arrange | positioned above the electrode substrate below (backlight side).

<Voltage-transmittance curve measurement>

First, the measurement was performed about the relationship between voltage (V) and transmittance (T) using the liquid crystal panel of an Example and the liquid crystal panel of a comparative example. 14 is a graph showing the relationship between the voltage V and the transmittance T of the liquid crystal panel of Example and the liquid crystal panel of Comparative Example. As shown in FIG. 14, the liquid crystal panel of an Example and the liquid crystal panel of a comparative example are substantially the same V-T curve. From this, it can be seen that the bottle brush has weak anchoring characteristics equivalent to that of the polymer brush.

<Measurement of Temperature-Azimuth Anchor Strength>

Next, using the liquid crystal panel of an Example and the liquid crystal panel of a comparative example, the measurement was performed about the relationship between temperature T and azimuth anchoring intensity A2. FIG. 15 is a graph showing the relationship between the temperature T and the azimuth anchoring strength A2 of the liquid crystal panel of the embodiment. FIG. 16 is a graph showing the relationship between the temperature T and the azimuth anchoring strength A2 of the liquid crystal panel of the comparative example. As shown to FIG. 15 and FIG. 16, the liquid crystal panel of an Example and the liquid crystal panel of a comparative example are an equivalent characteristic. From this, it can be seen that the bottle brush has weak anchoring characteristics equivalent to that of the polymer brush.

In general, weak anchoring (zero-side anchoring) refers to a case where the anchoring strength is less than 10 ^-6 [J / m ² ], and heavy anchoring means that the anchoring strength is 10 ^-5 to 10 ^-4 [J / m ² ]. Strong anchoring refers to a case where the anchoring strength is greater than 10 ⁻⁴ [J / m ² ]. For example, in the Example of FIG. 15, it is a weak anchoring (zero anchoring) state at 25 degreeC or more, and it is a medium anchoring state at low temperature.

Thereby, also when the bottle brush was used as an oriented film, it was confirmed that the weak anchoring surface equivalent to the time when the polymer brush was formed as an oriented film is implement | achieved. From the above, it was confirmed that the weak anchoring characteristics equivalent to those of the polymer brush can be obtained and low voltage driving and high transmittance LCD can be realized.

2: bottle brush 3: main chain
4: graft side chain 5: coexistence
6: bottle brush layer 10: liquid crystal display
11: liquid crystal panel (liquid crystal display element) 11f: surface
11r: back 12: backlight unit
13A: substrate 13B: substrate
14A. 14B: polarizer 15: electrode layer
16: weak anchoring alignment layer 17: strong anchoring alignment layer
18: liquid crystal layer 20A: electrode wire
E: electric field Lp: positive liquid crystal molecule
Ln: negative liquid crystal molecule

Claims (17)

The alignment film is composed of a bottle brush having a main chain and a graft side chain,
The main chain is a (meth) acrylate having a hydroxyl group, and the graft side chain is a (meth) acrylate or a glycol ether-based (meth) acrylate having an alkyl group.

delete The method of claim 1,
The graft side chain is covalently bonded to the substrate.

delete delete The method according to any one of claims 1 to 3,
The bottle brush is a crosslinkable liquid crystal display device.
A first substrate having an electrode layer formed thereon;
A second substrate facing the first substrate,
A liquid crystal layer between the electrode layer and the second substrate,
A first alignment layer disposed between the electrode layer and the liquid crystal layer and formed of a bottle brush;
A second alignment layer positioned between the liquid crystal layer and the second substrate and having an anchoring value greater than that of the first alignment layer
Liquid crystal display device comprising a.

delete The method according to any one of claims 1, 3, and 7,
A liquid crystal display element driven by a transverse electric field.

delete Forming an electrode layer on the first substrate,
Forming a first alignment layer that is a bottle brush layer on the electrode layer;
Forming a second alignment layer having a larger anchoring value than the first alignment layer on the second substrate;
Disposing the second substrate over the first substrate such that the first alignment layer and the second alignment layer face each other;
Injecting a liquid crystal between the first alignment layer and the second alignment layer;
The manufacturing method of the liquid crystal display element containing the process of orienting the said liquid crystal.
The method of claim 11,
The manufacturing method of the liquid crystal display element whose process of orienting the said liquid crystal is a rubbing method.
The method of claim 11,
The manufacturing method of the liquid crystal display element whose process of orienting the said liquid crystal is a photo-alignment method. The method of claim 7, wherein
The second alignment layer is a liquid crystal display device made of polyimide.
The method of claim 7, wherein
The bottle brush has a main chain and a graft side chain,
The main chain is a (meth) acrylate having a hydroxyl group, and the graft side chain is a (meth) acrylate or a glycol ether-based (meth) acrylate having an alkyl group.
The method of claim 7, wherein
The liquid crystal layer maintains a state in which the liquid crystal molecules of the liquid crystal layer are aligned in a predetermined initial alignment direction on the second alignment layer side in a state where an electric field is applied to the electrode layer, and the liquid crystal molecules of the liquid crystal layer on the first alignment layer side. The liquid crystal display element in which the orientation direction of is changed from the initial orientation direction to the direction along the electric field in the plane parallel to the surface of the first substrate.
The method of claim 7, wherein
The liquid crystal layer maintains a state in which the liquid crystal molecules of the liquid crystal layer are aligned in a predetermined initial alignment direction on the second alignment layer side in a state where an electric field is applied to the electrode layer, and the liquid crystal molecules of the liquid crystal layer on the first alignment layer side. The liquid crystal display element in which the orientation direction of is changed from the initial orientation direction to the direction perpendicular to the electric field in the plane parallel to the surface of the first substrate.

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