KR20180020875A - Liquid crystal display device and Method of fabricating the same - Google Patents

Abstract

An object of the present invention is to manufacture an in-plane switching (IPS) liquid crystal display device, capable of performing display with higher transmittance while driving liquid crystal molecules with a low voltage, in a simple and low-cost manner. An alignment film is composed of a bottle brush.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a liquid crystal display device,

The present invention relates to a liquid crystal display element and a method of manufacturing the liquid crystal display element.

TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), and the like are available as driving methods of liquid crystal display elements.

Among them, the IPS system 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 substrate surface with respect to the liquid crystal molecules filled between the two substrates. Such IPS liquid crystal display devices are excellent in visual characteristics and are applied to a wide range of devices including cellular phones, televisions, and the like.

In the conventional 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 in a state in which no electric field is applied.

As a method of adjusting the alignment direction of the liquid crystal molecules in the IPS liquid crystal panel, there is a method of forming an alignment film made of polyimide (PI) or the like on a substrate and rubbing the surface of the alignment film in a predetermined direction by rayon or cotton cloth A rubbing method), a method of generating anisotropy on the surface of a polyimide film by irradiation with polarized ultraviolet rays (photo alignment method), or the like. By these treatments, the liquid crystal molecules are strongly bound to the substrate surface and are oriented in a certain direction. Patent Document 1 is disclosed as a related art of the structure including such an alignment film.

In the structure described in Patent Document 1, the liquid crystal molecules are strongly confined by the alignment film. Therefore, even if an electric field is applied to the liquid crystal layer, the alignment direction of the liquid crystal molecules starts to change without applying a voltage of a certain magnitude, that is, a threshold value, without changing the alignment direction of the liquid crystal molecules.

Further, since the liquid crystal molecules are strongly confined by the alignment film, when the electric field is applied to the liquid crystal layer, the alignment direction of the liquid crystal molecules in the vicinity of the alignment film does not change from the initial alignment direction, The orientation direction of the liquid crystal molecules changes. In the IPS-mode liquid crystal panel, the contrast change is performed by using the retardation change accompanied by the orientation change of the liquid crystal molecules as described above.

In general, the transmittance of an IPS-mode liquid crystal panel is expressed by the following equation.

Equation 1

Where? Is the liquid crystal molecular alignment angle at the time of voltage application to the initial alignment direction,? N is the refractive index anisotropy of the liquid crystal, d is the cell gap, and?

From this equation, it is understood that a transmittance of 50% is ideally achieved when the orientation angle?, The refractive index anisotropy? N, and the cell gap d are properly selected (monochrome type). However, in reality, the design parameters of the IPS panel are determined in consideration of not only the transmittance but also all the conditions such as the driving voltage, the response time, and the yield. As a result, the transmittance of a practical IPS panel is reduced to half of the ideal value.

On the other hand, with the commercialization of organic EL (electroluminescence) display, it has become necessary to further improve the characteristics of the liquid crystal display. Particularly, reduction of power consumption and improvement of luminance (transmittance) have become very important developments in order to differentiate the organic EL display from the organic EL display. From this background, there is a strong demand for low voltage driving of the IPS panel and high transmittance.

In order to improve the transmissivity of the electrode, for example, in Patent Document 2, an anchoring (zero anchoring) is applied to at least one of the comb-like electrode substrate and the counter substrate, In order to realize an orientation film, a method of producing a polymer brush on a substrate by living radical polymerization is described.

In the present specification, 'zero plane anchoring' means that liquid crystal molecular orientation in the in-plane direction is controlled in the horizontal direction or diagonal direction, but the liquid crystal molecule orientation forcibly is in the zero state, that is, the liquid crystal molecules are aligned in the horizontal direction with respect to the substrate, Means that there is no liquid crystal molecular orientation forcible force in the liquid crystal molecule.

Patent Document 1: Japanese Patent Publication No. 2940354 Patent Document 2: JP-A-2015-125205

However, in order to produce a polymer brush on a substrate, since it is necessary to immerse each substrate in a polymerization solution in which a monomer is dissolved and perform a polymerization reaction for a long time at a high temperature under deoxygenation, the production of the substrate becomes complicated and costly, It was impossible to cope.

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

In an embodiment of the present invention, the bottle brush has a main chain and a graft side chain.

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

In an embodiment of the present invention, the bottle brush is characterized in that it is crosslinked.

In an embodiment of the present invention, a bottle brush layer is formed on one of the two substrates facing each other, and a polyimide layer is formed on another one of the substrates.

According to an embodiment of the present invention, the bottle brush layer is formed on the electrode substrate.

Further, in an embodiment of the present invention, it is characterized in that it is driven by a transverse electric field.

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.

Further, a method of manufacturing a liquid crystal display element of the present invention includes a step of forming a bottle brush layer on a substrate, a step of injecting liquid crystal between the substrate on which the bottle brush is formed, and a step of orienting the liquid crystal .

In an embodiment of the present invention, the step of orienting the liquid crystal is a rubbing method.

Further, in an embodiment of the present invention, the step of orienting the liquid crystal is a photo-alignment method.

According to the present invention, it is possible to manufacture a transverse electric field driving liquid crystal display element capable of performing display with a higher transmittance while driving liquid crystal molecules with a low voltage, and to manufacture a large-sized substrate easily and at low cost.

1 is a cross-sectional view showing a schematic structure of a liquid crystal display shown as a first embodiment of the present invention.
Fig. 2 is a diagram showing the distribution of the orientation of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the first embodiment in a state in which liquid crystal having a positive dielectric anisotropy is used and an electric field is applied. Fig.
3 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the first embodiment in a state in which a liquid crystal having a positive dielectric anisotropy is used and no electric field is applied.
4 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in a liquid crystal panel of the liquid crystal display shown in the first embodiment, in which liquid crystal having a positive dielectric anisotropy is used and an electric field is applied.
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 a second embodiment.
FIG. 7 is a diagram showing the distribution of the orientation of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the second embodiment in a state where a liquid crystal having negative dielectric anisotropy is used and an electric field is applied.
8 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the second embodiment in a state where a liquid crystal having negative dielectric anisotropy is used and no electric field is applied.
9 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown in the second embodiment in a state where a liquid crystal having negative dielectric anisotropy is used and an electric field is applied.
10 is a cross-sectional view showing a schematic structure of a liquid crystal display shown as a third embodiment.
11 is a diagram showing the distribution of the orientation of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the third embodiment in a state in which liquid crystal having a positive dielectric anisotropy is used and an electric field is applied.
12 is a cross-sectional view showing a schematic structure of a liquid crystal display shown as a fourth embodiment.
13 is a diagram showing the distribution of the orientation of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the fourth embodiment in a state in which a liquid crystal having a negative dielectric constant anisotropy is used and an electric field is applied.
14 is a graph showing the relationship between the voltage (V) and the transmittance (T) of the liquid crystal panel of the embodiment and the liquid crystal panel of the comparative example.
15 is a graph showing the relationship between the liquid crystal panel temperature T and azimuth angle anchoring strength A2 of the embodiment.
16 is a graph showing the relationship between the temperature T of the liquid crystal panel and the azimuth angle anchoring strength A2 of the comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid crystal display element and a liquid crystal display element manufacturing method according to the present invention will be described with reference to the drawings, with reference to the drawings.

≪ First Embodiment >

The liquid crystal has a positive type in which the dielectric anisotropy is positive and a negative type in which the dielectric anisotropy is negative. The positive type liquid crystal has a large genetic property in the long axis direction of the liquid crystal molecule and a small direction in the direction perpendicular to the long axis direction. In the negative type, the dielectric property is small in the long axis direction of the liquid crystal molecule and large in the direction orthogonal to the long axis direction. In the present embodiment, a case of using a positive type liquid crystal will be described.

1 is a cross-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 the liquid crystal panel of the liquid crystal display shown as the first embodiment, in which liquid crystal having an anisotropy of dielectric constant is used and an electric field is applied. Fig. Fig. 3 is a diagram showing the relationship between the electrode lines and the liquid crystal molecule alignment direction in the liquid crystal panel of the liquid crystal display shown as the first embodiment, in which the liquid crystal having the dielectric constant anisotropy is used and no electric field is applied. 4 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the first embodiment in a state in which a liquid crystal having a positive dielectric anisotropy is used and an electric field is applied.

As shown in Figs. 1 and 2, the liquid crystal display 10 includes a liquid crystal panel (liquid crystal display element) 11 and a backlight unit 12 for providing light to the liquid crystal panel 11.

The backlight unit 12 uniformly irradiates light input from a light source (not shown) provided on the back surface of the liquid crystal panel 11 toward the surface 11f side from the back surface 11r side of the liquid crystal panel 11 . The backlight unit 12 transmits light input from a light source (not shown) provided at one end of the backlight unit 12 in a direction parallel to the surface 11f of the liquid crystal panel 11, Called edge light type that irradiates the light from the back surface 11r side of the light guide plate 11 toward the surface 11f side can be used. The backlight unit 12 is a so-called direct-type liquid crystal display panel in which light input from a light source provided on the rear face 11r side of the liquid crystal panel 11 is irradiated from the rear face 11r side to the front face 11f side of the liquid crystal panel 11 May be used.

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

Each of the substrates 13A and 13B is made of a glass or resin substrate, and is arranged parallel to each other at a predetermined interval.

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

An example of the counter substrate is a color filter substrate. In general, a color filter substrate is formed by forming a black matrix on a glass substrate to prevent unwanted light spots and then patterning R (red), G (green) and B (blue) colored layers, . When these substrates 13B are used, the surface of the substrate 13B may be coated with a transparent resin and cured to form a planarized film.

The surface of the substrate 13B may be subjected to a planarizing process as required. The planarization treatment is not particularly limited and can be carried out by using methods known in the art. An example of the planarization treatment is a method of forming a planarization film on the surface of the substrate 13B. A UV curable transparent resin or the like may be coated on the surface of the substrate 13B and UV-cured.

The polarizing plate 14A is provided on the side of the substrate 13A disposed on the side of the backlight unit 12 opposite to the backlight unit 12 or on the side opposite to the backlight unit 12. The polarizing plate 14B is provided on the side of the substrate 13B located away from the backlight unit 12 on the side opposite to the backlight unit 12 or on the side opposite to the backlight unit 12. [ These polarizing plates 14A and 14B have transmission axis directions perpendicular to each other. Here, the transmission axis direction of the polarizing plate 14A is set to a 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 set in the direction Y parallel to the substrate 13B Is set. That is, the polarizing plate 14A and the polarizing plate 14B are disposed such that their transmission axis directions are perpendicular to each other, that is, they are orthogonal Nicols.

The electrode layer 15 is provided on the substrate 13A. In this embodiment, the electrode layer 15 is provided on the substrate 13A on the side of the backlight unit 12 on the side opposite to the backlight unit 12. The electrode layer 15 is formed by juxtaposing a plurality of electrode lines 20A along the surface of the substrate 13A and has a so-called comb-like electrode structure. Here, as shown in Fig. 3, each of the electrode lines 20A is formed in a straight line so 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 layer 15 is juxtaposed at regular intervals along the direction X orthogonal to the direction Y in a plane parallel to the surface of the substrate 13A.

2 and 4, in the electrode layer 15 as described above, when a predetermined voltage is applied to each of the electrode lines 20A of the electrode layer 15, In this embodiment, an electric field E in a direction X parallel to the substrate 13A and the substrate 13B is generated.

The weak anchoring alignment film 16 is formed on the substrate 13A on the side of the backlight unit 12 on the opposite side of the backlight unit 12. [ The steel anchoring orientation film 17 is formed on the side of the substrate 13B located away from the backlight unit 12 on the side opposite to the backlight unit 12. [

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

Herein, the weak anchoring alignment film 16 and the steel anchoring alignment film 17 are different in orientation binding force for restricting the alignment direction of the liquid crystal molecules Lp.

2, when the applied voltage is equal to or higher than the threshold voltage when the electric field E is generated by applying the voltage, the weak anchoring alignment film 16 is formed on the weak anchoring alignment film 16 of the liquid crystal layer 18, The liquid crystal molecules Lp are detached from the restraint of the anchoring alignment film 16. The alignment direction of the liquid crystal molecules Lp changes from the initial alignment direction (direction Y in Fig. 2) in a plane parallel to the surfaces of the substrates 13A and 13B according to the applied voltage magnitude.

On the other hand, in the steel anchoring orientation film 17, even if an electric field E is generated by applying a voltage, the liquid crystal molecules 8 on the strong anchoring orientation film 17 in the liquid crystal layer 8 are aligned in the long axis direction on the substrates 13A, (Direction Y in Fig. 2) substantially aligned with the orientation direction (direction Y in Fig. 2) parallel to the surface of the anisotropic alignment film 16, i.e., the alignment direction of the weakly anchoring alignment film 16 (direction Y).

As described above, when the electric field E is applied to the weak anchoring alignment film 16 and the strong anchoring alignment film 17, the weak anchoring alignment film 16 of the liquid crystal layer 18 deviates from the orientation forcing effect of the weak anchoring alignment film 16 The alignment direction of the liquid crystal molecules Lp is changed while the alignment direction of the liquid crystal molecules Lp is maintained by the strong anchoring alignment film 17 on the side of the strong anchoring alignment film 17.

As a result, in the liquid crystal layer 18, the alignment direction of the liquid crystal molecules (Lp) is different when the electric field (E) of the threshold value or more is applied on the weak anchoring alignment film 16 side and the strong anchoring alignment film 17 side. As a result, the amount of displacement of the alignment angle with respect to the initial alignment direction gradually increases from the side of the strong anchoring alignment film 17 toward the side of the weakened anchoring alignment film 16, and the liquid crystal molecules Lp are transferred to the spirally twisted alignment state, The liquid crystal molecules Lp in the vicinity of the weak anchoring alignment film 16 are oriented in a direction parallel to the electric field (E) direction. That is, it is in an aligned state that is twisted by 90 degrees from the side of the strong anchoring alignment film 17 toward the side of the weakened anchoring alignment film 16.

The alignment state of the liquid crystal layer 18 at the time of applying the voltage is the same as the alignment state of the liquid crystal at the time of no voltage ratio in the TN system. Therefore, the optical design of the liquid crystal panel 11 is performed so as to satisfy ΔnP »λ (Δn is refractive index anisotropy of liquid crystal, P is helical pitch of liquid crystal, λ is wavelength of light), or Mauguin Condition It is possible to generate a luminous flux effect in the liquid crystal layer 18.

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

Equation 2

Herein, u = d? N /?? / ?, where d is the cell gap (thickness of the liquid crystal layer 18) and? Is the twist angle of the liquid crystal molecules Lp. In this embodiment, the weak anchoring alignment film 16 Of the liquid crystal molecules on the side of the steel anchoring orientation film 17 and the orientation direction of the liquid crystal molecules on the side of the steel anchoring orientation film 17. In the present embodiment, since? =? / 2, u = 2d? N / ?.

In the liquid crystal panel 11, positive liquid crystal molecules Lp are used and the polarizing plate 14A and the polarizing plate 14B are arranged orthogonally to each other so that the transmission axis directions thereof are orthogonal to each other. The direction of the transmission axis of the polarizing plate 14B is an electric field (Direction Y in Fig. 1) with respect to the steel anchoring orientation film 17 for adjusting the alignment direction of the liquid crystal molecules Lp in the unexposed state (E). The liquid crystal molecules Lp are aligned in the alignment treatment direction with respect to the strong anchoring alignment film 17 and orthogonal to the transmission axis direction of the polarizing plate 14A in the electric field (E) The light from the side of the polarizing plate 14A can not pass through the polarizing plate 14A.

On the other hand, in the state where the electric field E is applied, the liquid crystal molecules Lp are aligned in the direction of the alignment treatment (direction Y in Fig. 2) of the strong anchoring alignment film 17 in the direction of the long axis at the side of the strong anchoring alignment film 17, Lt; RTI ID = 0.0 > orientation. ≪ / RTI > On the other hand, on the weak anchoring alignment film 16 side, the alignment direction of the liquid crystal molecules Lp starts to change in the plane parallel to the substrate 13A due to application of the electric field E above the threshold value, The major axis direction of the liquid crystal molecules Lp follows a direction parallel to the electric field E, that is, a direction X parallel to the substrate 13A. At this time, the optical condition of the liquid crystal panel 11 is designed so as to satisfy the maturity condition and the formula (2) to have the maximum value, so that the linearly polarized light incident on the liquid crystal layer 18 maintains the polarization state And transmitted through the polarizing plate 14B and emitted 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 the present embodiment can be made maximum (50% when the absorption of the polarizing plate is assumed to be 0). Generally, when the cell gap d is large, the response speed is lowered. Therefore, the optical design of the liquid crystal panel desirably selects the so-called first minimum condition among a plurality of conditions in which the formula (2) has the maximum value.

As described above, in the liquid crystal panel 11 of the present embodiment, the polarizing plate 14A and the polarizing plate 14B are arranged in an orthogonal Nicols arrangement using the positive liquid crystal molecules Lp, and the transmission axis direction of the polarizing plate 14B is shifted from the electric field (Direction Y in Fig. 1) with respect to the direction of the orientation treatment for the steel anchoring orientation film 17 for adjusting the orientation direction of the liquid crystal molecules Lp in the non-exposed state. According to this structure, when a predetermined electric field E of a threshold value or more is applied to the liquid crystal panel 11, the liquid crystal molecules Lp move from the strong anchoring orientation film 17 side toward the weak anchoring orientation film 16 side, The amount of displacement in the alignment direction with respect to the direction of the axis becomes larger and the transition is made to the spirally twisted alignment state. As a result, the light having passed through the polarizing plate 14A from the backlight unit 12 side is changed in polarization plane along the orientation direction distribution of the liquid crystal molecules Lp from the weakening anchoring orientation film 16 side toward the strong anchoring orientation film 17 side And is emitted through the opposite polarizing plate 14B.

As described above, the liquid crystal panel 11 adopts the IPS driving method in which the liquid crystal molecules Lp are displaced in the plane along the surfaces of the substrates 13A and 13B as a liquid crystal driving system, while controlling light on / off by using optical rotation do.

However, the above-described steel anchoring alignment film 17 is formed, for example, as follows. First, an alignment film made of polyimide or the like is formed on the substrate 13B. Thereafter, the roller with the rayon and cotton cloth is wound around the surface of the alignment film by rubbing in the predetermined direction (rubbing method) or rotating with the rotation of the roller and the substrate 13B while maintaining the distance between the roller and the substrate 13B constant, Thereby generating anisotropy on the surface of the alignment film made of polyimide (photo alignment method). The strong anchoring alignment film 17 whose alignment direction is set by these rubbing method, photo alignment method or the like gives stronger alignment forcing force to the liquid crystal molecule Lp than the weak anchoring alignment film 16.

The weak anchoring alignment film 16 is formed from a bottle brush. The bottle brush is a type of comb-like polymer to which side chains (branches) are bonded from several different points on the main chain (stem). Particularly when the branched density (graft density, segment density) of side chains is high, molecular bottle brushes, or cylindrical polymer brushes. It is known that the bottle brush has a cylinder-shaped shape of the main body stretched by the exclusion volume effect of the side chain. And the shape is named as resembling the shape of a brush used for cleaning a bottle or a flask. The synthesis of the bottle brush includes a grafting-to method in which a side chain is introduced into a stem polymer, a grafting-from method in which monomers are polymerized from a macro initiator (a stem polymer having a polymerization active point), a macromonomer (having a polymerizable functional group Polymer-based polymer). It is known that bottle brushes have properties equivalent to rich polymer brushes (rich brush effect).

An example of the chemical structure of the 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-based monomers, (meth) acrylamide-based monomers and styrene-based monomers. For example, R ₁ in the general formula 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), R _5: -H or _{-CH 3, R 6: - (} C = O) -OR (R: alkyl group comprising a crosslinked Etc.). In addition, the subscript l ₁ is the repeating unit having a side-chain polymer, l ₂ is a repeating unit not having a side chain polymer, m has had the liquid crystal and affinity and low point glass transition as will be described later addition of soluble branched polymer in the coating solvent The number of repeating units, n represents the number of repeating units of the side chain polymer forming the chemical crosslinking as described later. The number obtained by adding l ₁ and l ₂ is comparable to the degree of polymerization of the entire main chain.

As the main chain, a segment containing a monomer capable of introducing a polymerization initiator by a grafting-from method is preferable. (Meth) acrylate having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate.

The side chain is preferably a segment having an affinity for liquid crystals, a low glass transition point and a monomer soluble in a coating solvent. (Meth) acrylate or polyethylene glycol mono (meth) acrylate having alkyl such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate or lauryl Methacrylate, and the like.

The side chain preferably has a segment containing a monomer which forms a chemical bridge. For example, monomers such as a trimethoxysilyl group, a triethoxysilyl group, and a silicon atom-containing (meth) acrylate having a dimethylsilicone chain can also be used. In this case, the bottle brush may be regarded as a core shell type, and the core may be a segment having affinity for liquid crystals, a low glass transition point and also having a monomer soluble in a coating solvent, and a shell comprising a segment containing a monomer Lt; / RTI > The chemical crosslinking reaction proceeds by heat, light, moisture and the like.

The bottle brush can be obtained by using a known living polymerization, but it is more preferable that the bottle brush is synthesized by a living radical polymerization method. Living radical polymerization refers to a polymerization reaction in which a chain transfer reaction and a termination reaction do not substantially occur in a radical polymerization reaction and the chain growth terminal remains active even after the monomer completes the reaction. In this polymerization reaction, the polymerization activity is maintained at the end of the produced polymer even after completion of the polymerization reaction, and the polymerization reaction can be started again when the monomer is added.

The characteristics of the living radical polymerization include the ability to synthesize a polymer having an arbitrary average molecular weight by controlling the concentration ratio of the monomer and the polymerization initiator, the molecular weight distribution of the resulting polymer is very narrow, And the like. In addition, living radical polymerization is sometimes referred to as controlled radical polymerization when it is omitted as 'LRP'.

In the polymerization method of the present invention, a radical polymerizable monomer is used as a monomer. Radically polymerizable monomer refers to a monomer having an unsaturated bond capable of performing radical polymerization in the presence of an organic radical. Such an unsaturated bond may be a double bond or a triple bond. That is, in the polymerization method of the present invention, any monomer known to perform living radical polymerization from the prior art can be used.

As the living radical polymerization method, various methods such as those listed below have been specifically reported. For example, a nitroxide mediated polymerization (hereinafter abbreviated as NMP method) using bond with dissociation of nitroxyl radicals, a heavy metal such as copper, ruthenium, nickel, and iron, and a ligand forming a complex thereof , Atom Transfer Radical Polymerization (hereinafter abbreviated as ATRP method) in which a halogen compound is polymerized as a starting compound, dithiocarboxylic acid ester, and the like are used as starting compounds, polymerization is carried out using an addition polymerizable monomer and a radical initiator A method using heavy metal compounds such as reversible addition fragmentation chain transfer polymerization (hereinafter abbreviated as RAFT method), organic tellurium and organic bismuth, organic antimony, antimony halide, organic germanium, halogenated germanium Degenerative transfer (hereinafter referred to as " DT method ") is developed, Wide research and development have been made.

The side chain preferably has a segment containing a monomer which forms a physical bridge. For example, it is possible to use the same block that the core and shell of the bottle brush are phase-separated. As an example, when a segment containing methyl methacrylate as a core or a segment containing styrene as a shell is used, the film is spontaneously phase-separated and is physically crosslinked 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 applying a bottle brush polymer previously prepared by the living radical polymerization method to the substrate 13A. As described above, the bottle brush 2 is a kind of comb-like polymer having a graft side chain 4 bonded to the main chain 3, and the graft side chains 4 of the bottle brush 2 are bonded to each other, The brushes 2 are coupled to each other. A certain number of the 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 . The Tg (transition temperature) of the bottle brush 2 is -5 DEG C or less.

5, the liquid crystal molecules Lp penetrate 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 swollen side chain 4 of the bottle brush 2 in contact with the swollen portion is swollen (the swollen state is not shown in the figure).

In this specification, the portion of the bottle brush 2 in which the liquid crystal molecule Lp penetrates is referred to as the coexistence portion 5 and the portion of the bottle brush 2 in which the liquid crystal molecule Lp does not infiltrate is referred to as the bottle brush layer 6 . 5, the coexistence section 5 and the bottle brush layer 6 are clearly distinguished from each other in view of facilitating the understanding of the present invention. In actuality, however, the boundary between the coexistence section 5 and the bottle brush layer 6 is distinguished It is difficult to do.

By using the bottle brush 2 as described above, the Tg (glass transition temperature) of the coexistence section 5 becomes a temperature significantly lower than the room temperature, so that the shape of the coexistence section 5 can be freely varied at room temperature. Therefore, the state of the coexistence section 5 is changed at the interface between the coexistence section 5 and the liquid crystal molecule Lp and the liquid crystal molecules Lp are aligned in the horizontal direction with respect to the substrate 13A, A state in which no orientation forcible force is applied (zero plane anchoring state) can be realized.

The Tg of the coexisting portion 5 varies depending on the type of the bottle brush 2 and the liquid crystal molecule Lp to be used and therefore can not be defined uniquely. Lower. The Tg of the coexistence portion 5 is also changed by the degree of penetration of the liquid crystal molecules Lp into the bottle brush 2 (i.e., the ratio between the bottle brush 2 and the liquid crystal molecules Lp). Concretely, the coexistence portion 5 on the side of the liquid crystal molecule Lp having a large proportion of the liquid crystal molecules Lp in the coexistence portion 5 has the bottle brush layer 6 having a low Tg and a low ratio of the liquid crystal molecules Lp, The Tg of the coexistence portion 5 on the side of the coexistence portion 5 increases.

However, as the bottle brush 2, since the Tg of the coexisting portion 5 can be set to a temperature sufficiently lower than the room temperature by using the bottle brush having a Tg of -5 DEG C or lower, a surface horizontal to the surface of the substrate 13A (Zero plane anchoring state) in which no orientation forcible force is applied in any direction within the plane while adjusting the orientation of the liquid crystal molecules Lp within the plane.

The bottle brush 2 forms a layer of the bottle brush 2 on the surface of the substrate 13A. Thickness of the layer of the bottle brush 2 is not particularly limited, but is generally several tens nm, more specifically 1 nm or more and less than 100 nm, and preferably 10 nm to 80 nm. In addition, the bottle brush (2) layer has a size excluding effect, and a certain size of material can not pass through the layer of the bottle brush (2). Therefore, even if the thickness of the layer of the bottle brush 2 is reduced, it is possible to prevent impurities from entering the liquid crystal molecules Lp from the substrate 13A side.

The bottle brush 2 is formed, for example, by applying a bottle brush polymer previously prepared by a living radical polymerization method to the substrate 13A. Herein, the term " living radical polymerization " means that the chain transfer end and the termination reaction do not substantially occur in the radical polymerization reaction, and the chain growth end remains active even after the radical polymerizable monomer completes the reaction Means a polymerization reaction.

The formation of the bottle brush polymer is also carried out according to the following procedure.

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

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

3. Bottle Brush Polymer Manufacturing

The application of the substrate 13A of the bottle brush polymer is carried out using existing facilities such as flexographic printing, inkjet printing or die coating. Thereafter, the substrate 13A is heated to an appropriate temperature, whereby 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 with the immobilization film interposed therebetween if necessary from the viewpoint of enhancing the fixability between the substrate 13A and the bottle brush 2. The immobilizing film is not particularly limited as long as it is excellent in fixability to the substrate 13A and the bottle brush 2, and those generally known in living radical polymerization can be used. An example of the immobilized film is a film formed from an alkoxysilane compound represented by the following general formula (2).

(2)

In the general formula (2), R ¹ is each independently an alkyl group of C1 ~ C3, and preferably a methyl group or an ethyl group, R ² are each independently a methyl group or an ethyl group, X is a halogen atom, preferably Br, n Is an integer of 3 to 10, more preferably an integer of 4 to 8.

It is preferable that the immobilizing film is covalently bonded to the bottle brush 2. When the immobilizing film and the bottle brush 2 are bonded by a covalent bond having strong bonding force, peeling of the bottle brush 2 can be sufficiently prevented. As a result, the possibility of degradation of the characteristics of the liquid crystal panel 11 is lowered and the reliability of the liquid crystal panel 11 is improved.

The method of forming the immobilized film is not particularly limited and may be suitably set according to the material to be used. For example, the immobilization film can be formed by immersing the substrate 13A in a solution for immobilizing a film, or applying the solution for immobilizing the film to the substrate 13A, followed by drying. Here, in order to form a fixed film on a predetermined portion, masking may be performed on a portion where a fixed film is not formed. Further, the substrate 13A may be cleaned before forming the immobilization film, if necessary.

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 a vacuum injection method using a capillary phenomenon, Filling) can be used. For example, in the case of using a vacuum injection method using a capillary phenomenon, the following procedure is performed.

First, an electrode layer 15 is formed on a one-sided substrate 13A by a known method, and then a bottle brush 2 is formed. On the other substrate 13B, a spacer is formed by a known method such as photolithography. Next, the one-side substrate 13A is cleaned and dried, and then a sealing material is applied, and the sealing material is superimposed on the other substrate 13B and cured by heating, UV irradiation, or the like. Here, it is necessary to open an injection port for injecting the liquid crystal molecules Lp into a part of the sealing material. Next, liquid crystal molecules (Lp) are injected between the substrates (13A, 13B) by a vacuum injection method from the injection port, and then the injection port is sealed.

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

As described above, according to the liquid crystal panel 11, since the backlight unit 12, the substrate 13A on which the weak anchoring alignment film 16 is formed, and the weak anchoring alignment film 16, A liquid crystal layer 18 disposed between the weak anchoring orientation film 16 and the strong anchoring orientation film 17 and driven by the liquid crystal molecules Lp to transmit or block light, And an electrode layer 15 provided on the substrate 13A and applying an electric field E to the liquid crystal molecules Lp. Further, when the electric field E is applied to the weak anchoring alignment film 16, the constraining force for restricting the alignment direction of the liquid crystal molecules Lp is smaller than that of the strong anchoring alignment film 17. [

The displacement angle of the liquid crystal layer 18 in the alignment direction of the liquid crystal molecules Lp gradually increases from the side of the strong anchoring alignment film 17 toward the direction of the weakened anchoring alignment film 16 in a state where the electric field E is applied.

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

According to the above configuration, the liquid crystal molecules Lp are driven using the optical rotation of the liquid crystal molecules Lp. According to such a configuration, since the light changes along the orientation of the liquid crystal molecules Lp and becomes transparent, it becomes possible to perform display with high transmittance.

By using the bottle brush 2 as described above, the Tg (glass transition temperature) of the coexistence section 5 becomes a temperature significantly lower than the room temperature, so that the shape of the coexistence section 5 can be freely varied at room temperature. Therefore, the state of the coexistence section 5 is changed at the interface between the coexistence section 5 and the liquid crystal molecule Lp and the liquid crystal molecules Lp are aligned in the horizontal direction with respect to the substrate 13A, A state in which no orientation forcible force is applied (zero plane anchoring state) can be realized.

In order to stably realize the weak anchoring state (zero plane anchoring state), it is necessary to use an alignment film which has high compatibility with liquid crystals and is strongly adhered to a substrate. It is also necessary to densely cover the interface so that the liquid crystal does not contact the substrate. Therefore, in order to form a conventional polymer brush on a substrate, it is necessary to immerse the substrate in the polymerization solution and polymerize at a high temperature for several hours. On the other hand, in the present invention, since the bottle brush 2 is dissolved in an organic solvent and the solution is applied to the substrate and heated, the bottle brush can be fixed on the substrate. Therefore, compared with the case of forming a weak anchoring orientation film with a polymer brush , And can be formed at low cost.

A problem in the case of forming a weakly anchoring alignment film with a conventional polymer brush will be described below.

(1) In order to produce a weak anchoring alignment film using a polymer brush, monomers are successively reacted and grown from the substrate surface, so that a simple technique such as a coating method can not be carried out. Since it is necessary to immerse the substrate in the polymerization solution, Only the area substrate can be manufactured.

(2) Since the polymer brush synthesis uses a living radical polymerization reaction, the reaction time is required for a long time such as 24 to 48 hours.

(3) Polymer brushes are not produced by a simple method of heating and polymerizing after application.

(4) Since the polymerization solution is an aromatic strong solvent, the acrylic resin dissolves.

On the other hand, an advantage of forming a weakly anchoring alignment film with a bottle brush will be described below.

(1) Since the LCD panel can be manufactured through the process of applying the bottle brush to the substrate after the bottle brush is manufactured in another place, it is not necessary to carry the large polymerization vessel into the LCD manufacturing line. Therefore, it is applicable to large-sized substrates of 1 m to 2 m square.

(2) Since the weak anchoring orientation film can be produced only by applying and firing the bottle brush, the time required for producing the orientation 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 existing alignment film manufacturing process (polyimide forming process) can be used, so that new facility investment is unnecessary.

(4) Since there is no step of heating in a polymerization solution, a weakly anchoring alignment film can be produced also on a resin member such as a color filter or a column spacer. Further, it is also possible to form it on a plastic long plate.

≪ Second Embodiment >

Next, a second embodiment of the liquid crystal display element according to the present invention will be described. In the second embodiment to be described below, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. The second embodiment has the same electrode layer 15 as in the first embodiment and drives the negative-type liquid crystal molecules Ln.

6 is a cross-sectional view showing a schematic configuration of a liquid crystal display shown as a second embodiment. Fig. 7 is a diagram showing the distribution of the alignment direction of liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the second embodiment in a state in which a liquid crystal having negative dielectric anisotropy is used and an electric field is applied. 8 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown in the second embodiment, in which liquid crystal having negative dielectric anisotropy is used and no electric field is applied. 9 is a diagram showing the relationship between the direction of the liquid crystal molecules and the direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown in the second embodiment, in which liquid crystal having negative dielectric anisotropy is used and an electric field is applied.

6 and 7, in this embodiment, the polarizing plate 14A and the polarizing plate 14B are arranged in an orthogonal Nicols arrangement, the transmission axis direction of the polarizing plate 14A is set to follow the direction Y, and the polarizing plate 14B ) Is set so as to follow the direction X. As shown in Fig.

The electrode layer 15 is formed by juxtaposing a plurality of electrode lines 20A along the surface of the substrate 13A. As shown in Figs. 12 and 13, each of the electrode lines 20A is formed in a straight line so that the major axis direction thereof extends along the direction Y in a plane parallel to the surface of the substrate 13A, for example. The electrode layer 15 is juxtaposed at regular intervals along the direction X orthogonal to the direction Y within a plane parallel to the surface of the substrate 13A.

The liquid crystal molecules Ln of the liquid crystal layer 18 have a negative dielectric anisotropy and a small negative dielectric constant in the major axis direction and a large negative major axis in the major axis direction. When the negative type liquid crystal molecules Ln are used as shown in FIG. 6 and FIG. 8, the orientation direction of the strong anchoring orientation film 17 for adjusting the orientation direction of the liquid crystal molecules Ln in the non- (Direction X in Fig. 8) perpendicular to the major axis direction of each electrode line 20A. The polarizing plate 14A and the polarizing plate 14B are arranged orthogonally to each other so that the transmission axis direction of the polarizing plate 14A is aligned with the direction of the liquid crystal molecules Ln in the non- ) (Direction Y in Fig. 8). Then, in the electric field (E) unenergized state, the light from the backlight unit 12 side is not transmitted.

As shown in Fig. 7, the negative-type liquid-crystal molecules Ln are aligned in the initial alignment state (direction of alignment) of the strong anchoring alignment film 17 along the direction of the orientation of the strong anchoring alignment film 17 on the side of the rigid anchoring alignment film 17, X). On the other hand, on the weak anchoring alignment film 16 side, the alignment angle is displaced in the plane parallel to the substrate 13A by the applied electric field E, and when the electric field intensity reaches a certain value, Along the direction Y whose major axis direction is perpendicular to the electric field E, that is, parallel to the substrate 13A. The displacement angle of the liquid crystal layer 18 in the alignment direction of the liquid crystal molecules Ln gradually increases from the side of the strong anchoring alignment film 17 toward the direction of the weakened anchoring alignment film 16 in the state in which the electric field E is applied in this manner. The alignment direction (direction Y) of the liquid crystal molecules Ln on the weak anchoring alignment film 16 side becomes orthogonal to the electric field E when the electric field equal to or greater than a certain value is applied and coincides with the transmission axis direction of the polarizing plate 14A Therefore, light passing through the polarizing plate 14A from the backlight unit 12 side is changed in polarization plane along the alignment direction distribution of the liquid crystal molecules Ln, and is emitted through the opposite polarizing plate 14B.

As described above, the liquid crystal panel 11 of the present embodiment using a liquid crystal having a negative dielectric constant anisotropy can also perform display with higher transmittance while driving the liquid crystal molecules Ln at a low voltage.

In the first to second embodiments, the so-called normaly black type liquid crystal panel 11 in which the display is dark when the voltage is not applied and becomes bright when the voltage is applied is described.

≪ Third Embodiment >

Next, a liquid crystal display element according to a third embodiment of the present invention will be described. In the third embodiment described below, the same reference numerals are assigned to the same components as those of the above-described embodiments, and the description thereof is omitted. In the third embodiment, the transmission axis direction of the polarizing plate 14A is different from that of the first embodiment.

10 is a cross-sectional view showing a schematic structure of a liquid crystal display shown as a third embodiment.

Fig. 11 is a diagram showing a liquid crystal molecule alignment direction distribution in a liquid crystal panel of a liquid crystal display shown as the third embodiment, in which liquid crystal having an integer dielectric constant anisotropy is used and an electric field is applied. Fig. In the first embodiment, the transmission axis direction of the polarizing plate 14A is the direction X, but is set to the direction Y in the third embodiment. Thus, the polarizing plates 14A and 14B are arranged such that their transmission axis directions are parallel to each other, that is, parallel Nicol.

10, the light having passed through the polarizing plate 14A from the backlight unit 12 side is emitted from the liquid crystal panel 11 while maintaining the polarized state and the polarizing plane, as shown in Fig. 10, It is released. At this time, since the polarization direction (direction Y) of the linearly polarized light incident on the liquid crystal layer 18 coincides with the transmission axis direction (direction Y) of the polarizing plate 14B, most of the light from the backlight unit 12 side And can transmit the polarizing plate 14B.

On the other hand, when a predetermined electric field E of a threshold value or more is applied to the liquid crystal panel 11 as shown in FIG. 11, on the side of the strong anchoring orientation film 17, the long axis direction is initialized along the orientation direction of the strong anchoring orientation film 17 As the magnitude of the applied electric field E increases while maintaining the alignment state (direction Y), the amount of displacement of the liquid crystal molecules Lp in the vicinity of the weak anchoring alignment film 16 in the alignment direction toward the initial alignment direction 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 weak anchoring alignment film 16 becomes parallel to the electric field E (direction X) The light from the side of the backlight unit 12 can not pass through the polarizing plate 14A.

In the so-called normaly black type liquid crystal panel 11 (see FIG. 1) in which the polarizing plates 14A and 14B are arranged so as to be parallel Nicols, the display is dark when the voltage is not applied and becomes bright when the voltage is applied , The liquid crystal panel 11 can be configured as a so-called normaly white type in which the display is bright when the voltage is not applied and becomes dark when the voltage is applied.

≪ Fourth Embodiment &

Next, a fourth embodiment of the liquid crystal display element according to the present invention will be described. In the fourth embodiment to be described below, the same components as those of the above-described embodiments are denoted by the same reference numerals and the description thereof is omitted. In the fourth embodiment, the transmission axis direction of the polarizing plate 14A is different from that of the second embodiment.

12 is a cross-sectional view showing a schematic structure of a liquid crystal display shown as a fourth embodiment.

Fig. 13 is a diagram showing a liquid crystal molecule alignment direction distribution in a liquid crystal panel of a liquid crystal display shown as the fourth embodiment, in which liquid crystal having a negative dielectric constant anisotropy is used and an electric field is applied. Fig. In the second embodiment, the transmission axis direction of the polarizing plate 14A is the direction Y, but is set in the direction X in the fourth embodiment. Thus, the polarizing plates 14A and 14B are arranged such that their transmission axis directions are parallel to each other, that is, parallel Nicol.

12, the light having passed through the polarizing plate 14A from the backlight unit 12 side is emitted from the liquid crystal panel 11 while maintaining the polarization state and the polarizing plane, It is released. At this time, since the polarization direction (direction X) of the linearly polarized light incident on the liquid crystal layer 18 coincides with the transmission axis direction (direction X) of the polarizing plate 14B, most of the light from the backlight unit 12 side And can transmit the polarizing plate 14B.

On the other hand, when a predetermined electric field E of a threshold value or more is applied to the liquid crystal panel 11 as shown in FIG. 13, on the side of the strong anchoring orientation film 17, As the magnitude of the applied electric field E increases while maintaining the alignment state (direction X), the amount of displacement of the liquid crystal molecules Lp in the vicinity of the weak anchoring alignment film 16 in the alignment direction toward the initial alignment direction 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 weak anchoring alignment film 16 side becomes a direction (direction Y) orthogonal to the electric field E, The light from the side of the backlight unit 12 can not pass through the polarizing plate 14A.

As described above, in the fourth embodiment, like the third embodiment, it is configured as a normaly white type.

While the preferred embodiments of the present invention have been described in detail, those skilled in the art will appreciate various modifications and equivalent arrangements.

Accordingly, 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, which is defined in the claims, are also included in the present invention.

For example, in the present embodiment, the weak anchoring alignment film 16 is disposed on the backlight unit 12 side and the strong anchoring alignment film 17 is disposed on the side away from the backlight unit 12, but the present invention is not limited thereto. The weak anchoring alignment film 16 may be disposed on the side separated from the backlight unit 12 and the steel 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.

That is, after the polyimide layer is formed on the substrate 13A provided with the electrode layer 15, the rubbing treatment is performed to form the steel anchoring orientation film 17. [ On the other hand, a bottle brush layer is formed on the substrate 13B to form a weakly anchoring alignment film 16. As described above, the anchoring value of the bottle bristle layer is smaller than the anchoring value of the polyimide layer. Thereafter, the substrate 13A and the substrate 13B are bonded to each other with a sealing agent interposed therebetween, and the liquid crystal panel 11 is manufactured by injecting liquid crystal thereinto.

In the first and second embodiments, the liquid crystal molecules L are oriented in the direction from the strong anchoring orientation film 17 side to the weakly anchoring orientation film 16 side in the state of applying the electric field E, The amount of displacement of the wobbles gradually increases and the wobbles are warped. Here, the liquid crystal molecules L have the maximum amount of displacement of the alignment angle of the liquid crystal molecules L in the middle portion between the strong anchoring alignment film 17 and the weak anchor alignment film 16, and the anchoring alignment film 16, The alignment angle shift amount of the liquid crystal molecules L may be the same (maximum state). In other words, the liquid crystal molecules L are spirally arranged in the region from the side of the strong anchoring orientation film 17 to the middle of the strong anchoring orientation film 17 and the weak anchoring orientation film 16 in the state of applying the electric field E, But may be arranged in the same manner in the region from the middle portion between the steel anchoring orientation film 17 and the weak anchoring orientation film 16 to the weak anchoring orientation film 16 side.

<Examples>

With respect to the configuration shown in this embodiment mode, since the demonstration experiment was performed using the liquid crystal panel modeled as described below, the results are shown below.

&Lt; Production of liquid crystal panel &

(Hereinafter referred to as an electrode substrate) formed with an ITO comb-shaped electrode (thickness: about 55 nm, electrode width L / inter-electrode distance S = 4 μm / 10 μm) , An opposing substrate) were bonded together, and a liquid crystal panel in which liquid crystal was filled in the gap was produced. On the electrode substrate of the liquid crystal cell of the example, a bottle brush was formed as an alignment film. The method of forming the bottle brush is as follows.

&Lt; Method of forming a bottle brush &

A methacrylate polymer having a living radical polymerization initiator in its side chain was used as a macro initiator. The macroinitiator was 50000 in terms of polymethyl methacrylate, Mn (number average molecular weight) was 50,000, PDI (molecular weight distribution) was 1.4, and main chain polymerization degree 1 was 200. A bottle brush obtained by introducing hexyl methacrylate (hereinafter abbreviated as HMA) and 3-methacryloxypropyltrimethoxysilane (hereinafter abbreviated as MOPS) into the side chain by living radical polymerization using the macroinitiator described above . The molecular weight was measured by GPC using a THF solvent. As a result, it was found that Mn was 230000 and PDI was 2.0 in terms of polymethyl methacrylate. The average number of repeating units of HMA and MOPS was m = 30 and n = 0.1, respectively.

<Bottle brush polymer coating>

0.1 part by mass of a bottle brush polymer was dissolved in THF to obtain 2.1 g of a THF solution (bottle brush polymer 5 wt%). The solution was spin-coated on a glass substrate with electrodes (rotation speed 3000 rpm, 60 seconds). Thereafter, the substrate was left under vacuum condition at 120 DEG C for 3 hours to crosslink the spin-coated film. Further, the cross-linked spin coating film was ultrasonically washed with THF.

On the other hand, on the opposite substrate side of the liquid crystal panel of the embodiment, a photo-spacer having a height of 3.0 mu m was formed and then coated with PI (JALS-16470 made by JSR) as an alignment film. The surface of the PI alignment layer was rubbed. 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 electrode were perpendicular to each other. The electrode substrate and the counter substrate were bonded together through a sealing material, and subjected to a sealing and curing treatment at 120 deg. C for 2 hours in a nitrogen atmosphere while being pressurized to prepare a blank cell. Thereafter, the negative liquid crystal was injected into the blank cell by the vacuum injection method, and then the injection port was sealed with the UV curable encapsulant. The electrode substrate was disposed on the lower side (backlight side) and the counter substrate was disposed on the upper side.

Further, the negative liquid crystal was a product of Merck Co., and the physical properties were as follows.

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

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

?? (dielectric anisotropy): -3.1 [1 kHz, 20 占 폚]]

ε⊥: 6.5

K1: 15.1 [pN, 20 &lt; 0 &gt; C]

K3: 14.7 [pN, 20 &lt; 0 &gt; C]

? 1 (rotational viscosity): 121 [mPas, 20 DEG C]

This liquid crystal corresponds to, for example, the liquid crystal mixture described in Example 22 (Table 45) of JP-A-2016-094622.

<Comparative Example>

The manufacturing procedure of the liquid crystal panel of the comparative example is as follows. (Hereinafter, referred to as an electrode substrate) on which a comb-like electrode made of ITO (thickness: about 55 nm, electrode width L / interelectrode distance S = 4 μm / 10 μm) Then, a liquid crystal panel filled with liquid crystal was produced.

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

Next, a solution prepared by mixing 0.05 g of starting material, 0.05 g of 2-bromo-2-methyl-N- (3- (triethoxysilyl) propyl) propanamide (BPA), 4.7 g of ethanol and 0.25 g of ammonia water The substrate was immersed overnight in a shaded state to fix the starting material on the substrate surface. Subsequently, the substrate was ultrasonically cleaned with acetone for 10 minutes and then blown with nitrogen gas to dry it. The PHMA brush was obtained by immersing the substrate on which BPA was immobilized by a polymerization solution (monomer: hexyl methacrylate, HMA / 29.74 g / 174.7 mmol, 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 the mixture was heated at 70 占 폚 for 7 hours to polymerize.

As a result of measurement of the prepolymer in the same patch by gel permeation chromatography, the molecular weight and the molecular weight distribution of the polymerized PHMA brush were estimated as 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 X-ray reflectance measurement (Ultima IV manufactured by Rigaku). In addition, the graft density (σ) of PHMA brush is the density of the polymer brushes is the same as the bulk polymer density (using a 1.00 g / cm ³ as PHMA density) on the _{assumption, σ = ρhN A / M (} ρ: bulk polymer density , h: film thickness of the polymer brush, N _a: Avogadro constant, M: was estimated as 0.12 chains / nm ² from the relation of the polymer brush molecular weight).

On the other hand, on the opposite substrate side of the liquid crystal panel of the comparative example, a photo-spacer having a height of 3.0 mu m was formed and then coated with PI (JALS-16470 made by JSR) as an alignment layer. The surface of the PI alignment layer was rubbed. 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 electrode were perpendicular to each other. The electrode substrate and the counter substrate were bonded together via a sealing material, and subjected to a sealing curing treatment at 120 ° C for 2 hours under a nitrogen atmosphere while being pressurized to prepare a blank cell. Thereafter, the negative liquid crystal was injected into the blank cell by the vacuum injection method, and then the injection port was sealed with the UV curable encapsulant. The liquid crystal used in the comparative example was the same negative liquid crystal as used in the examples. The electrode substrate was disposed on the lower side (backlight side) and the counter substrate was disposed on the upper side.

<Measurement of voltage-transmittance curve>

Measurements were made on the relationship between the voltage (V) and the transmittance (T) using the liquid crystal panel of the first embodiment and the liquid crystal panel of the comparative example. 14 is a graph showing the relationship between the voltage (V) and the transmittance (T) of the liquid crystal panel of the embodiment and the liquid crystal panel of the comparative example. As shown in Fig. 14, the liquid crystal panel of the embodiment and the liquid crystal panel of the comparative example are almost the same V-T curves. From this point, it can be seen that the bottle brush has weak anchoring properties equivalent to the polymer brush.

<Temperature-azimuthal anchoring strength measurement>

Next, the relationship between the temperature (T) and the azimuthal anchoring strength (A2) was measured using the liquid crystal panel of the embodiment and the liquid crystal panel of the comparative example. 15 is a graph showing the relationship between the temperature T and the azimuth angle anchoring strength A2 of the liquid crystal panel of the embodiment. 16 is a graph showing the relationship between the temperature (T) and the azimuth angle anchoring strength (A2) of the liquid crystal panel of the comparative example. As shown in Figs. 15 and 16, the liquid crystal panel of the embodiment and the liquid crystal panel of the comparative example are equivalent. From this point, it can be seen that the bottle brush has weak anchoring properties equivalent to the polymer brush.

In general, weak anchoring refers to a case where the anchoring strength is less than 10 ^-6 [J / m ² ], and medium anchoring refers to an anchoring strength of 10 ^-5 to 10 ^-4 [J / m ² ] , And the anchoring of steel means that the anchoring strength is larger than 10 ^-4 [J / m ² ]. For example, in the embodiment shown in Fig. 15, there is a slight anchoring (zero anchoring) state at 25 DEG C or higher, and a medium anchoring state at a lower temperature.

As a result, it was confirmed that even when a bottle brush was used as an alignment film, a weakly anchored surface equivalent to that obtained when a polymer brush was formed as an alignment film was realized. From the above, it was confirmed that weak anchoring characteristics equivalent to the polymer brush can be obtained, and low voltage driving and high transmittance LCD can be realized.

2: Bottle brush 3: Main chain
4: Grafted side chain 5:
6: bottle brush layer 10: liquid crystal display
11: liquid crystal panel (liquid crystal display element) 11f: surface
11r: back surface 12: backlight unit
13A: substrate 13B: substrate
14A. 14B: polarizer 15: electrode layer
16: weak anchoring orientation film 17: steel anchoring orientation film
18: liquid crystal layer 20A: electrode line
E: electric field Lp: positive type liquid crystal molecule
Ln: Negative liquid crystal molecule

Claims (13)

Wherein the alignment film is formed of a bottle brush.
The method according to claim 1,
Wherein the bottle brush has a main chain and a graft side chain.
3. The method of claim 2,
And the graft side chain is covalently bonded to the substrate.
The method according to claim 2 or 3,
Wherein the graft side chain is a copolymer.
The method according to claim 2 or 3,
Wherein the graft side chain is a block copolymer.
4. The method according to any one of claims 1 to 3,
Wherein the bottle brush is crosslinked.
Wherein a bottle brush layer is formed on one of two opposing substrates and a polyimide layer is formed on another one of the substrates.
8. The method of claim 7,
Wherein the bottle brush layer is formed on the electrode substrate.
The method according to any one of claims 1 to 3, 7, and 8,
A liquid crystal display element driven by a transverse electric field.
9. The method according to claim 7 or 8,
Wherein an anchoring value of the bottle brush layer is smaller than an anchoring value of the polyimide layer.
A step of forming a bottle brush layer on a substrate,
A step of injecting liquid crystal between the substrate on which the bottle brush is formed,
And aligning the liquid crystal.
12. The method of claim 11,
Wherein the step of orienting the liquid crystal is a rubbing method.
12. The method of claim 11,
Wherein the step of orienting the liquid crystal is an optical alignment method.

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