KR20130085036A - Liquid crystal display device - Google Patents

Abstract

The liquid crystal display device of the present invention is a liquid crystal display device which displays by applying an electric field to a liquid crystal material sandwiched between a pair of transparent substrates, wherein the liquid crystal material is a liquid crystal material exhibiting a blue phase, and this The liquid crystalline material exhibits optical isotropy when no electric field is applied, and shows optical anisotropy when an electric field is applied, or optical anisotropy when no electric field is applied, and optical isotropy when applying an electric field, and the pair of The organic film which does not have the ability to orientate the said liquid crystalline material is formed in the surface by the side of the liquid crystalline material of at least 1 sheet of a transparent substrate.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device in which a liquid crystal phase called a "blue phase" is used as a display medium, and the display is performed in accordance with a change in optical anisotropy when no voltage is applied and when voltage is applied.

In the liquid crystal display device of the present invention, the response to the change in the applied electric field is quick and high contrast can be realized.

Liquid crystal displays have a feature of being lightweight and having low power consumption, and are widely used in personal computer monitors, mobile phones, and televisions. However, there are drawbacks such as a slow response to an applied electric field, insufficient resolution of moving picture display, and light leakage even in dark display because the liquid crystal material as a display medium has optical anisotropy. Furthermore, an alignment treatment process for using the liquid crystal material in an alignment state is essential.

Under such circumstances, recently, a liquid crystal display device using a liquid crystal phase called a "blue phase" of a liquid crystal substance has been proposed.

The liquid crystal material used in the ordinary liquid crystal display device is a nematic liquid crystal, and in the case of an image having optical isotropy, the order of the position of each molecule is lost, but the order of orientation is maintained.

On the other hand, the blue phase BP is an optically isotropic phase appearing in an extremely narrow temperature range (typically 1K or less) between a chiral nematic liquid crystal and an isotropic liquid, and in order of appearance from the high temperature side, respectively, BPIII, Are classified into BPII and BPⅠ. It is known that BP I has body center cubic and BP II has simple cubic symmetry, but BP III is amorphous, and its detailed structure is not well known yet.

When an electric field is applied to a blue phase, it is known that local molecular reorientation, lattice distortion, and phase transition occur (liquid crystal, 2005 (9), p82 (Non Patent Literature 1)).

Local molecular reorientation occurs at a relatively low electric field, local molecular reorientation according to electric field strength, the resulting birefringence is proportional to the power of the electric field strength (Kerr effect), and the response time is an order of microseconds. When the electric field strength is increased, lattice distortion occurs, and phase transitions continue. The lattice distortion is a phenomenon in which the lattice constant changes with the electric field, and the response time is an order of milliseconds. A phase transition is a phenomenon which transitions from a blue phase to a chiral nematic phase, and then to a nematic phase, and the response time is an order more than a second.

When using a blue phase as a display medium, the narrow temperature range becomes a problem. In this regard, Kikuchi et al. Have broadened the temperature range of BP I by adding a polymer to a liquid crystal material showing a blue phase, thereby realizing a response speed of several hundred microseconds by local reorientation (H. Kikuchi et al., Nature Mater. 2002 (1), p64 (non-patent document 2) and Y. Hisakado et al., Adv. Mater., 2005 (17), p96 (non-patent document 3)). Coles et al. Also reported color switching resulting from lattice distortion caused by the expansion of the temperature range of BP I and the application of an electric field by adding chiral dopants to the dimer liquid crystal composition (H.Coles & MNPivnenko, Nature, 20). (Non-Patent Document 4)). The addition of the chiral dopant was also attempted by the group of Hirosaki University, a national university corporation (Japanese Patent Publication No. 2009-8897 (Patent Document 1)). In addition, a display device using the Kerr effect has been proposed using a blue phase or a cubic phase as a medium (Japanese Patent Laid-Open No. 2005-202390 (Patent Document 2)). In addition, the technique of improving display quality by applying a liquid crystal aligning film to the liquid crystal display device using a blue phase was proposed (Japanese Unexamined-Japanese-Patent No. 2005-227759 (patent document 3)).

However, although the display method described in the said nonpatent literatures 2 and 3 has the advantage that a response speed becomes a little faster, it has a drawback that it is difficult to make a uniform and bright state. In addition, although the technique described in Nonpatent Literature 4 and Patent Literature 1 is a high speed as the phase transition from the blue phase only in response time, the change in birefringence due to application of an electric field is not sufficient, and the bright state The drawback is that it is difficult to indicate.

Moreover, according to the technique of patent document 2, the electrical characteristics of a liquid crystal display device are not enough. According to the technique of patent document 3, contrast is very inadequate.

About contrast, not all of what is conventionally known as a liquid crystal display device using a blue phase is satisfactory. In particular, light leakage in the dark display is not eliminated by any technique, and light leakage occurs in orders of several percent, resulting in a decrease in contrast, and improvement is desired.

This invention is made | formed in view of said situation. SUMMARY OF THE INVENTION An object of the present invention is to provide high-speed response while using a blue phase as a display medium, and to maintain good amorphousness when the display medium should exhibit amorphousness (optical isotropy) to form good dark display. An object of the present invention is to provide a liquid crystal display device that realizes high contrast display.

According to this invention, the said subject of this invention is

A liquid crystal display device which displays by applying an electric field to a liquid crystal substance sandwiched between a pair of transparent substrates,

The liquid crystal material is a liquid crystal material exhibiting a blue phase, and this liquid crystal material is

When the electric field is not applied, it shows optical isotropy, and when the electric field is applied, it shows optical anisotropy, or

When an electric field is not applied, it shows optical anisotropy, when an electric field is applied, it shows optical isotropy, and

An organic film (however, this organic film does not have the ability to orient the liquid crystal material) is formed on a surface of at least one liquid crystal material side of the pair of transparent substrates.

It is achieved by the said liquid crystal display device characterized by the above-mentioned.

It is preferable that the polarizing plate is further bonded to both surfaces of the said liquid crystal display device.

In the liquid crystal display device of the present invention, high-speed response is possible, and since the amorphous property of the medium is maintained stably when the display medium should exhibit optical isotropy, there is no light leakage in the dark display, and the display with good contrast can be obtained. It can be realized.

Therefore, the liquid crystal display device of this invention is advantageous at the point with high contrast with respect to what is conventionally known as a liquid crystal display device using a blue phase.

1 is an exploded perspective explanatory view of a liquid crystal display device manufactured in Examples and Comparative Examples.

(Mode for carrying out the invention)

The liquid crystal display device of the present invention has a structure in which a liquid crystal substance is sandwiched between a pair of transparent substrates. Electrodes are formed on one or both surfaces of the pair of transparent substrates.

Examples of the substrate include glass such as float glass and soda glass; Transparent substrates made of a synthetic resin such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, poly (alicyclic olefin), and hydrogenated products of poly (alicyclic olefin) can be used.

In this invention, two sheets of the above board | substrates are used as a pair.

Here, when the electrode is formed only on one side of a pair of transparent substrates, the said electrode consists of a pair of electrodes patterned by the comb-tooth shape, and the surface of a transparent substrate is applied by applying a voltage between this pair of electrodes. An electric field is generated horizontally with respect to. On the other hand, when electrodes are formed in both of a pair of transparent substrates, these electrodes are electrodes which have shapes, such as stripe shape and a fishbone shape, respectively, and apply a voltage between these electrodes to the surface of a transparent substrate. The electric field is generated perpendicular to the.

As an electrode, a transparent electrode is preferable, As a material which comprises such a transparent electrode, NESA (registered trademark of US PPG company) consisting of tin oxide (SnO ₂ ), indium oxide-tin oxide (In ₂ O ₃ -SnO _{2, for example)} ITO etc. which consist of) are mentioned.

In order to obtain a patterned electrode, it is possible to form, for example, a method of forming a pattern by photo-etching after forming an electrode without a pattern, a method of using a mask having a desired pattern when forming an electrode, and the like.

As the substrate in the liquid crystal display of the present invention, a pair of electrodes patterned in the form of comb teeth is formed on one surface (only one side) of a pair of transparent substrates, and a voltage is applied between the pair of electrodes. It is preferable to set it as the structure which an electric field generate | occur | produces horizontally with respect to the surface of a transparent substrate.

The organic film which does not have the ability to orientate the said liquid crystalline material is formed in the surface by the side of the liquid crystalline material of at least 1 sheet among a pair of transparent substrates mentioned above.

Here, when an electrode is formed only in one side of a pair of transparent substrate, the organic film is formed on the electrode formation surface of the transparent substrate which has the said electrode at least. In this case, it is preferable that the organic film which does not have the ability to orientate the said liquid crystalline material is formed also in the surface on the liquid crystalline material side of the transparent substrate which does not have an electrode. On the other hand, when the electrode is formed in both of a pair of transparent substrates, the organic film is formed on the electrode formation surface of at least one side of a transparent substrate. In this case, it is preferable that the organic film which does not have the performance which orientates a liquid crystalline substance is also formed on the electrode formation surface of the other transparent substrate.

In the above, the organic film "does not have the ability to orient the liquid crystalline substance" means that the organic film has a steroid skeleton, (alkyl) bicyclohexyl group, (alkyl) biphenyl group, (alkyl) cyclohexylphenyl group, It means having no alkyl group having 4 or more carbon atoms, fluoroalkyl group having 2 or more carbon atoms, cyano group and fluorine atom.

It is preferable that the surface tension of the said organic film is 40 dyne / cm or less. By using the organic film which has such surface tension, interaction of the said organic film and liquid crystal molecule is reduced. As a result, when a display medium should show amorphousness, it is preferable at the point which can maintain the amorphousness stably and the dark display without light leakage is obtained.

It is preferable that the said organic film consists of at least 1 sort (s) of organic polymer chosen from the group which consists of a polyamic acid, the imide (imidized polymer) of polyamic acid, an acrylic resin, and a polyorganosiloxane,

It is more preferable that it consists of at least 1 sort (s) of organic polymer chosen from the group which consists of polyamic acid, the imide of polyamic acid, and polyorganosiloxane. All of said organic polymers do not have the ability to orientate the said liquid crystalline substance.

The said polyamic acid can be obtained by making tetracarboxylic dianhydride and diamine react. By dehydrating and ring-closing this polyamic acid, the imide of said polyamic acid can be obtained. Tetracarboxylic dianhydride and diamine as a raw material of polyamic acid and its imide are, respectively, a group having a steroid skeleton, (alkyl) bicyclohexyl group, (alkyl) biphenyl group, (alkyl) cyclohexylphenyl group, and carbon number 4 It is preferable not to have any of the above alkyl group, a C2 or more fluoroalkyl group, a cyano group, and a fluorine atom.

As said tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride, etc. are mentioned, for example. Specific examples thereof include aliphatic tetracarboxylic acid dianhydrides such as butanetetracarboxylic dianhydride;

As alicyclic tetracarboxylic dianhydride, For example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5- tricarboxy cyclopentyl acetic dianhydride, 1,3,3a, 4, 5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 , 5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3- Oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 5- (2,5-dioxotetrahydro-3 -Furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornan-2: 3,5: 6-2 anhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-2 anhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3 , 5,8,10-tetraon and the like;

As aromatic tetracarboxylic dianhydride, a pyromellitic dianhydride etc. are mentioned, for example.

As tetracarboxylic dianhydride used for synthesize | combining the said polyamic acid, it is preferable to contain alicyclic tetracarboxylic dianhydride among these, Furthermore, 2,3,5- tricarboxy cyclopentyl acetic dianhydride and It is preferable to contain at least 1 sort (s) chosen from the group which consists of 1,2,3,4-cyclobutane tetracarboxylic dianhydride.

The tetracarboxylic acid dianhydride used for synthesizing the polyamic acid may be selected from the group consisting of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride. Is contained preferably in an amount of 10 mol% or more, more preferably 20 mol% or more, and more preferably in the range of 2, 3, 5-tricarboxycyclopentyl acetic acid dianhydride and / And most preferably at least one selected from the group consisting of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride.

As said diamine, aliphatic diamine, alicyclic diamine, aromatic diamine, diamino organosiloxane, etc. are mentioned, for example. As these specific examples, As an aliphatic diamine, For example, 1, 1- metha xylylenediamine, 1, 3- propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, etc .;

As the alicyclic diamine, for example, 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

As aromatic diamine, for example, p-phenylenediamine, 4,4'- diaminodiphenylmethane, 4,4'- diaminodiphenyl sulfide, 1,5- diaminonaphthalene, 2,2'-dimethyl -4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 4,4'-diaminodiphenylether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-(m-phenylenediisopropylidene) bisaniline, 4, 4'-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3, 6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, 1,4- Bis- (4-aminophenyl) -piperazine, 3,5-diaminobenzoic acid, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 1,1-bis ( 4-((aminophenyl) methyl) phenyl) -4-heptylcycle Hexane, 1,1-bis (4-((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4- (4- Heptylcyclohexyl) cyclohexane, diamine having a fluorene structure and diamine having a 9,10-dihydroanthracene structure;

As diamino organosiloxane, 1, 3-bis (3-aminopropyl)-tetramethyl disiloxane, etc. are mentioned, for example.

As a diamine which has the said fluorene structure, For example, 2, 7- diamino fluorene, the compound represented by following formula (1);

As diamine which has a 9,10- dihydroanthracene structure, the compound etc. which are represented, for example by following formula (2) are mentioned, respectively:

(R ¹ in formulas (1) and (2) is a single bond, a phenylene group, and a group -Ph-O- (where Ph is a phenylene group);

R <^2> is a C1-C6 alkyl group, a C1-C6 alkoxy group, or a halogen atom, respectively;

a is an integer of 0-4, respectively; And

A plurality of a's and a plurality of R ^{1 's,} and when present, a plurality of R ^{2' s} may be the same or different, respectively).

The phenylene group of R ¹ may be any of 1,2-phenylene group, 1,3-phenylene group and 1,4-phenylene group.

As a compound represented by said Formula (1), For example, the compound etc. which are represented by each of following formula (1-1)-(1-3);

As a compound represented by said Formula (2), the compound etc. which are represented by each of (2-1)-(2-3), etc. are mentioned, respectively.

As said diamine, it is preferable to contain at least 1 sort (s) chosen from the group which consists of a diamine which has a fluorene structure, and the diamine which has a 9,10- dihydroanthracene structure. As at least 1 sort (s) of ratio chosen from the group which consists of the diamine which has a fluorene structure in the said diamine, and the diamine which has a 9,10- dihydroanthracene structure, it is preferable to set it as 50 mol% or more with respect to all the diamines. It is more preferable to set it as 70 mol% or more, and it is especially preferable to set it as 90 mol% or more. Most preferably, at least one selected from the group consisting of diamines having a fluorene structure and diamines having a 9,10-dihydroanthracene structure is used as the diamine.

In synthesizing polyamic acid, it is preferable to make the use ratio of tetracarboxylic dianhydride and diamine into the ratio which the acid anhydride group of tetracarboxylic dianhydride becomes 0.2-2 equivalent with respect to 1 equivalent of amino group of diamine, More preferably, it is a ratio which becomes 0.3-1.2 equivalent.

The synthesis reaction of the polyamic acid is preferably in an organic solvent, preferably at -20 ° C to 150 ° C, more preferably at a temperature of 0 to 100 ° C, preferably 0.1 to 24 hours, more preferably The reaction time is 0.5 to 12 hours.

Here, examples of the organic solvent include non-protic polar solvents, phenols and derivatives thereof, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like. As specific examples of the organic solvent, for example, N-methylpyrrolidone, γ-butyrolactone, butyl cellosolve, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-dimethylimide Zolidinone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphortriamide, etc. are mentioned, One or more types selected from these can be used preferably.

The imidized polyimide (imidized polymer) of polyamic acid can be obtained by dehydrating and ring-closing the polyamic acid obtained by making it above.

Dehydration ring closure of polyamic acid, Preferably it is performed by the method of heating a polyamic acid, or the method of heating as needed by adding a dehydrating agent and a dehydration ring closure catalyst in the solution which melt | dissolved polyamic acid in the organic solvent. Among these, it is preferable to follow the latter method.

In the method of adding the dehydrating agent and the dehydrating ring-closure catalyst to the solution of the polyamic acid, for example, acid anhydrides such as acetic anhydride, propionic anhydride and trifluoroacetic anhydride can be used as the dehydrating agent. It is preferable that the use ratio of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of the dark acid structure of polyamic acid. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine and triethylamine can be used. It is preferable to make the use rate of a dehydration ring-closure catalyst into 0.01-10 mol with respect to 1 mol of dehydrating agents to be used.

Examples of the organic solvent used in the dehydration ring-closure reaction include the organic solvents exemplified for use in the synthesis of polyamic acid.

The reaction temperature of the dehydration ring-closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

As said polyorganosiloxane, it is preferable to use the polyorganosiloxane which has an epoxy group. As a ratio of the epoxy group in polyorganosiloxane, it is preferable that it is 1,000 g / mol or less as epoxy equivalent, and it is more preferable to set it as 150-300 g / mol.

It is preferable that it is 500-50,000, and, as for the weight average molecular weight Mw of polystyrene conversion measured by the gel permeation chromatography about polyorganosiloxane, it is more preferable that it is 1,000-20,000.

Such polyorganosiloxane is a method of reacting a silane compound having an epoxy group or a mixture of a silane compound having an epoxy group with another silane compound in the presence of dicarboxylic acid and alcohol (manufacturing method 1) or a method of hydrolyzing and condensing ( It can manufacture by the manufacturing method 2). The silane compound and other silane compound which have an epoxy group used as a raw material are the group which has a steroid skeleton, a (alkyl) bicyclohexyl group, a (alkyl) biphenyl group, an (alkyl) cyclohexylphenyl group, a C4 or more alkyl group, and carbon number, respectively It is preferable not to have any of two or more fluoroalkyl groups, cyano groups, and fluorine atoms (however, if they are included as part of an alkoxy group directly bonded to a silicon atom, they are not limited thereto).

As a silane compound which has such an epoxy group, 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl triethoxysilane, 3-glycidyloxypropyl methyl dimethoxysilane, 3 -Glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyldimethylmethoxysilane, 3-glycidyloxypropyldimethylethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxy Silane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, etc. are mentioned, One or more types selected from these can be used.

As said other silane compound, 1 type chosen from the group which consists of ethyltrimethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane, for example It is preferable to use the above, and it is especially preferable to use 1 or more types chosen from the group which consists of tetramethoxysilane and tetraethoxysilane.

Since it is preferable that the polyorganosiloxane in this invention has such epoxy equivalents, it is preferable that the use ratio of the silane compound used as a raw material is suitably set so that a desired epoxy equivalent may be obtained. As will be described later, by reacting the epoxy group of the polyorganosiloxane with a suitable carbon acid, it is possible to obtain a polyorganosiloxane having a desired group. In this case, a certain proportion of the epoxy group is consumed. Therefore, in this case, it is preferable to set the use ratio of the said silane compound after considering the ratio of the epoxy group consumed only.

Hereinafter, the method of making the silane compound in the manufacturing method 1 for manufacturing polyorganosiloxane react in presence of dicarboxylic acid and alcohol is demonstrated.

Examples of the dicarboxylic acid used herein include oxalic acid, malonic acid, a compound having two carboxy groups bonded to an alkylene group having 2 to 4 carbon atoms, benzenedicarboxylic acid, and the like. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, etc. are mentioned, It is preferable to use 1 or more types selected from these. Particularly preferably oxalic acid.

It is preferable that the use ratio of dicarboxylic acid is made into the quantity which becomes 0.2-2.0 mol, and the quantity of the carboxy group with respect to a total of 1 mol of the alkoxy groups which the silane compound used as a raw material is made into 0.5-1.5 mol. More preferred.

As said alcohol, primary alcohol can be used suitably, It is preferable to use a C1-C4 aliphatic primary alcohol, methanol, ethanol, i-propanol, n-propanol, i-butanol, sec-butanol, and It is more preferable to use 1 or more types chosen from the group which consists of t-butanol, and it is especially preferable to use 1 or more types chosen from the group which consists of methanol and ethanol.

It is preferable to make into the ratio which the ratio of the silane compound and dicarboxylic acid which occupy the whole amount of the reaction solution to become 3 to 80 weight%, and the ratio of the alcohol used in the manufacturing method 1 to 25 to 70 weight% It is more preferable to.

It is preferable to make reaction temperature into 1-100 degreeC, More preferably, it is 15-80 degreeC. The reaction time is preferably 0.5 to 24 hours, more preferably 1 to 8 hours.

In reaction of the silane compound of the manufacturing method 1, it is preferable not to use other solvent other than the above alcohol.

In the above manufacturing method, it is estimated that the polyorganosiloxane which is the (co) condensate of a silane compound produces | generates by alcohol acting on the intermediate produced | generated by reaction of a silane compound and dicarboxylic acid.

Next, the hydrolysis-condensation reaction of the silane compound in the manufacturing method 2 is demonstrated.

This hydrolysis-condensation reaction can be performed by making a silane compound and water react in presence of a catalyst, Preferably in a suitable organic solvent.

It is preferable that the ratio of the water used here is 0.5-2.5 mol as an amount with respect to the total of 1 mol of the alkoxy groups which the silane compound used as a raw material has.

As said catalyst, an acid, a base, a metal compound, etc. are mentioned. As an example of such a catalyst, hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, oxalic acid, maleic acid, etc. are mentioned, for example.

As the base, any of an inorganic base and an organic base can be used, and examples of the inorganic base include ammonia, sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide and potassium ethoxide;

As the organic base, for example, tertiary organic amines such as triethylamine, tri-n-propylamine, tri-n-butyl amine, pyridine, 4-dimethylaminopyridine; Tetramethylammonium hydroxide etc. are mentioned, respectively.

As a metal compound, a titanium compound, a zirconium compound, etc. are mentioned, for example.

It is preferable to set it as 10 weight part or less with respect to a total of 100 weight part of the silane compound used as a raw material, It is more preferable to set it as 0.001-10 weight part, It is preferable to set it as 0.001-1 weight part Do.

As said organic solvent, alcohol, ketone, an amide, ester, and other aprotic compounds are mentioned, for example. As said alcohol, any of partial ester of the alcohol which has one hydroxyl group, the alcohol which has two or more hydroxyl groups, and the alcohol which has two or more hydroxyl groups can be used. As the ketone, monoketone and β-diketone can be preferably used. Of these, it is preferable to use partial esters of alcohols having a plurality of hydroxyl groups, and in particular, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether , Propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, etc. can be illustrated preferably, It is especially preferable to use 1 or more types chosen from these.

As a usage ratio of an organic solvent, it is preferable to set it as the ratio which becomes 1 to 90 weight% as a ratio which the total weight of components other than the organic solvent in a reaction solution occupies for the total amount of reaction solution, and becomes 10 to 70 weight% It is more preferable to set it as a ratio.

The water added at the time of the hydrolysis-condensation reaction of a silane compound can be added intermittently or continuously in the silane compound which is a raw material, or in the solution which melt | dissolved a silane compound in the organic solvent.

The catalyst may be added in advance in the silane compound as a raw material or in a solution in which the silane compound is dissolved in an organic solvent, or may be dissolved or dispersed in water to be added.

It is preferable to make reaction temperature into 1-100 degreeC, More preferably, it is 15-80 degreeC. The reaction time is preferably 0.5 to 24 hours, more preferably 1 to 8 hours.

When the polyorganosiloxane manufactured as mentioned above has an epoxy group, the polyorganosiloxane which has a desired group can be obtained by making this epoxy group react with a suitable carbon acid. Examples of the carboxylic acid that can be used include a group having a steroid skeleton, a (alkyl) bicyclohexyl group, a (alkyl) biphenyl group, a (alkyl) cyclohexylphenyl group, an alkyl group having 4 or more carbon atoms, a fluoroalkyl group having 2 or more carbon atoms, and a cyano group And it is preferable that it is a carboxylic acid which does not have any of a fluorine atom, For example, following formula (3):

R ³ -COOH (3)

(In formula (3), R <^3> is a hydrogen atom, a C1-C3 alkyl group, a C3-C8 alicyclic group, or a phenyl group which may be substituted by the C1-C3 alkyl group or the alkoxy group.)

The compound represented by this is mentioned.

It is preferable to set it as 1 mol or less with respect to 1 mol of the epoxy group which polyorganosiloxane has, and, as for the usage ratio of carbonic acid, it is more preferable to set it as 0.05-0.9 mol%.

Reaction of the polyorganosiloxane and epoxy acid which have an epoxy group can be performed according to a well-known method as a reaction method of an epoxy group and a carboxy group.

The organic polymer produced as mentioned above is used for manufacture of the liquid crystal display device of this invention, after refine | purifying according to an appropriate method as needed.

The organic film in this invention can be formed by apply | coating and heating the solution which melt | dissolved the above organic polymers in a suitable solvent on a board | substrate. As the solvent, for example, at least one selected from aprotic polar solvents, phenols and derivatives thereof, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like can be used, and particularly preferably N-methylpy. Ralidone, butyl cellosolve, γ-butyrolactone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide, tetramethylurea and hexamethyl It is preferable to use one or more selected from the group consisting of phosphortriamide.

As content rate of the organic polymer in this solution, it is preferable to set it as 1-10 weight%, and it is more preferable to set it as 1.5-9 weight%.

The detail of the formation method of an organic film is mentioned later.

The liquid crystal material exhibits a blue phase, and this liquid crystal material is

When the electric field is not applied, it shows optical isotropy, and when the electric field is applied, it shows optical anisotropy, or

When no electric field is applied, optical anisotropy is shown, and when the electric field is applied, optical isotropy is shown.

Among them, it is preferable that the dielectric anisotropy exhibiting optical isotropy when no electric field is applied and the optical anisotropy when applying an electric field are negative liquid crystalline materials.

As such a liquid crystalline substance showing a blue phase, for example, 1,2-difluoro-4- [trans-4- (trans-4-n-propylcyclohexyl) cyclohexyl] benzene, 1,2-difluoro Rho-4- [trans-4- (trans-4-n-pentylcyclohexyl) cyclohexyl] benzene, 1,2-difluoro-4- [trans-4- (trans-4-n-heptylcyclohexyl ) Cyclohexyl] benzene, etc., It is preferable to use 1 or more types selected from these, It is preferable to use 2 or more types selected from these, It is especially preferable to mix and use all these. desirable.

You may mix and use these liquid crystalline substances, a chiral agent, a high molecular compound, a polymerizable monomer, a polymerization initiator, a suitable solvent, etc. with these liquid crystalline substances.

The liquid crystal display device of this invention can be manufactured according to the manufacturing method of a well-known liquid crystal display device.

First, the organic film which does not have the ability to orientate a liquid crystalline substance is formed on at least one single side of a pair of transparent substrates.

When the electrode is formed on the transparent substrate, on the electrode formation surface of the substrate,

When the electrode is not formed, on one side of the transparent substrate,

An organic film can be formed on a board | substrate by apply | coating the solution containing said organic polymer, respectively, and forming a coating film, and then superheating the said coating film.

As a coating method of an organic polymer solution, the appropriate coating methods, such as a roll coater method, a spinner method, the printing method, the inkjet method, are mentioned, for example.

The formed coating film is preferably preheated (prebaked), and then calcined (postbaked) to obtain an organic film. The prebaking conditions are preferably 0.1 to 5 minutes at 40 to 120 ° C, and the postbaking conditions are preferably 120 to 300 ° C, more preferably 150 to 250 ° C, preferably 5 to 200 minutes, More preferably, it is 10 to 100 minutes.

The film thickness of the organic film after postbaking becomes like this. Preferably it is 0.001-1 micrometer, More preferably, it is 0.005-0.5 micrometer.

At the time of coating of the organic polymer solution, in order to further improve the adhesion between the transparent substrate or the electrode and the organic film, before the functional silane compound, titanate compound and the like are applied and heated on the transparent substrate and the electrode in advance. (Pre) treatment may be performed.

Although the rubbing process may be performed to the organic film formed by a well-known method, in order to exhibit the effect of this invention to the maximum, it is preferable not to perform a rubbing process.

Subsequently, the liquid crystal cell of the structure which arrange | positioned the above-mentioned liquid crystalline substance in the clearance gap of a pair of transparent substrates including the transparent substrate in which the organic film which does not have the ability to orientate a liquid crystalline substance to the single side | surface obtained in this way is formed. To prepare. The thickness (width of the gap between the transparent substrates) of the layer of the liquid crystal material is preferably set to 0.001 to 1 µm, more preferably 0.005 to 0.5 µm.

In order to manufacture such a liquid crystal cell, the following two methods are mentioned, for example.

As a 1st method, the method of performing the following series of processes is mentioned. First, a pair of transparent substrates are arranged to face each other via a gap (cell gap), and the peripheral portions of the two substrates are bonded using a sealing agent. At this time, in the case where the organic film and / or the electrode are formed on the transparent substrate, the surfaces thereof face the inside of the opposing arrangement. After filling and filling the liquid crystal material into the cell gap partitioned by the substrate surface and the sealing agent, the injection hole is sealed. By the above process, a liquid crystal cell can be manufactured.

The second method is a method of performing the following series of steps. First, an ultraviolet-ray curable sealing material is apply | coated, for example to the predetermined | prescribed place on one transparent substrate (the surface when an organic film and / or an electrode is formed) among a pair of board | substrates. In addition, a liquid crystalline substance is added dropwise to a predetermined number of places on the substrate surface (or organic film surface if present). Thereafter, the other substrate is bonded (when the organic film and / or electrode is formed so that its surface is downward), and the liquid crystalline material is spread on the entire surface of the substrate. Subsequently, ultraviolet light is irradiated to the entire surface of the transparent substrate to cure the sealing agent. By the above process, a liquid crystal cell can be manufactured.

And preferably, the liquid crystal display device of this invention can be obtained by bonding a polarizing plate to the outer surface of the said liquid crystal cell.

As said sealing agent, the epoxy resin etc. which contain the aluminum oxide sphere as a spacer, a hardening | curing agent, etc. can be used, for example.

As a polarizing plate used on the outer side of a liquid crystal cell, the polarizing plate which sandwiched the polarizing film called "H film | membrane" which absorbed iodine while extending | stretching polyvinyl alcohol, and the cellulose acetate protective film, the polarizing plate which consists of H film itself, etc. are mentioned. have.

The liquid crystal display device of the present invention produced in this manner is used in combination with a suitable backlight device. The liquid crystal display device of the present invention preferably operates as follows.

That is, when no voltage is applied, no electric field is applied, and since the liquid crystalline material exhibits a blue phase and is optically isotropic, it exhibits a dark color without passing light from the backlight. At this time, since the liquid crystalline material used in the present invention does not have any order of alignment, a uniform dark color can be displayed without substantially light leakage.

However, when a voltage is applied to the liquid crystal display of the present invention, an electric field (an electric field in a horizontal or vertical direction with respect to the transparent substrate depending on the configuration of the electrode) is applied according to the applied voltage, and thus a blue to chiral nematic phase is applied. Further, the phase transition to the nematic phase becomes optically anisotropic, and passes through the light from the backlight and shows bright colors.

The response speed of the change from the dark to the light accompanying the voltage application and the change from the light to the dark accompanying the voltage release can be very fast as compared with the conventionally known liquid crystal display device.

The liquid crystal display device of the present invention exhibits a high response speed as described above and exhibits high contrast.

Example

Synthesis Example 1

44.83 g (0.20 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride and 69.69 g (0.20 mol) of the compound represented by the above formula (1-1) were dissolved in 565 g of -butyrolactone, at 60 ° C. The reaction was carried out for 6 hours.

The obtained reaction solution was poured into a large excess of methanol to precipitate the reaction product, and then the precipitate was recovered, washed with methyl alcohol, and dried at 40 ° C. for 15 hours under reduced pressure to obtain 112.3 g of polyamic acid. The logarithmic viscosity (η _ln ) of this polyamic acid was 1.22 dl / g.

35.2 g of pyridine and 27.6 g of acetic anhydride were added to a solution in which 40.0 g of the polyamic acid obtained above was dissolved in 800 g of γ-butyrolactone, and dehydration ring closure reaction (imidization reaction) was performed at 110 ° C for 4 hours. Subsequently, 38.5 g of imidation polymer (B-1) was obtained by performing precipitation, separation, washing, and drying of a reaction product similarly to the case of the said polyamic acid. The logarithmic viscosity ((eta) _ln ) of this imidation polymer (B-1) was 1.23 dl / g.

Synthesis Example 2

In Synthesis Example 1, 75.29 g (0.20 mol) of a compound represented by Formula (1-2) was used instead of the compound represented by Formula (1-1), and the logarithmic viscosity ( η _ln) of the polyamic acid was obtained 107.8g 1.08dl / g.

Next, except having used 40.0 g in the said polyamic acid, dehydration ring-closure reaction was performed similarly to the synthesis example 1, and 37.5 g of imidation polymers (B-2) were obtained. The logarithmic viscosity ((eta) _ln ) of this imidation polymer (B-2) was 1.13 dl / g.

Synthesis Example 3

196 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and 212 g (1.0 mol) of 2,2'-dimethyl-4,4'-diaminobiphenyl were N-methyl-2-pi It melt | dissolved in 4,050 g of ralidone and reacted at 40 degreeC for 3 hours, and obtained 3,700 g of solutions containing 10 weight% of polyamic acid (A-1). The solution viscosity of this polyamic acid solution was 170 mPa * s.

Synthesis Example 4

In the reaction vessel, 100.0 g of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were added and mixed at room temperature. Subsequently, 100 g of deionized water was dripped over 30 minutes from the dropping funnel, and then reaction was performed at 80 degreeC for 6 hours, stirring under reflux. After the completion of the reaction, the organic layer was taken out and washed with a 0.2% by weight ammonium nitrate aqueous solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure to obtain a polyorganosiloxane having an epoxy group. 10.0 g of polyorganosiloxane having this epoxy group, 30.28 g of methyl isobutyl ketone, 1.18 g of butyric acid and 0.10 g of UCAT18X (trade name, manufactured by San Apro Co., Ltd.) were placed in a 200 mL three-necked flask and stirred at 100 ° C. for 48 hours. Reaction was carried out. After the completion of the reaction, the solution obtained by adding ethyl acetate to the reaction mixture was washed three times, the organic layer was dried using magnesium sulfate, and then the solvent was distilled off to obtain 8.1 g of polyorganosiloxane (S-1).

Comparative Synthesis Example 1

10.8 g (0.10 mol) of p-phenylenediamine and 52.3 g (0.10 mol of 3,5-diaminobenzoic acid 3-cholestanyl) in place of the compound represented by the said Formula (1-1) in the said synthesis example 1 ) Was used in the same manner as in Synthesis example 1 to obtain 105.7 g of polyamic acid having a logarithmic viscosity (η _ln ) of 1.23 dl / g.

Subsequently, 38.0 g of imidized polymer (b-1) was obtained by performing dehydration ring-closure reaction similarly to the synthesis example 1 except having used 40.0g in the said polyamic acid. The logarithmic viscosity ((eta) _ln ) of this imidation polymer (b-1) was 1.34 dl / g.

In the following example, the liquid crystal display device by the structure of this invention was actually manufactured, and the operation | movement confirmation was performed.

The exploded perspective explanatory drawing of the liquid crystal display device manufactured by the Example and the comparative example was shown in FIG.

The liquid crystal display of FIG. 1 has a pair of board | substrate which consists of the transparent substrate 1 in which the pair of comb-shaped electrodes arrange | positioned with the distance of 10 micrometers between electrodes, and the transparent substrate 2 which does not have an electrode. The electrode formation surface of the transparent substrate 1 and the single side | surface of the transparent substrate 2 have organic membrane, respectively.

In this liquid crystal display device, a liquid crystal material (not shown) is disposed in a gap in which the pair of transparent substrates described above are disposed to face each other via a spacer. And polarizing plates are arrange | positioned at the outer both surfaces of the said pair of transparent substrates, respectively. This liquid crystal display device is used in combination with a backlight (not shown) disposed below the transparent substrate 1.

The liquid crystal material in the liquid crystal display of FIG. 1 exhibits a blue phase when no voltage is applied (that is, when no electric field is applied), and is optically isotropic, thus showing dark color without transmitting light from the backlight. . However, by applying a voltage between the pair of electrodes, an electric field is generated in a direction horizontal to the transparent substrates 1 and 2, whereby the liquid crystal material is phase-transferted and optically anisotropic to transmit light from the backlight. This results in bright colors.

Example 1

[Preparation of Organic Polymer Solution]

As the organic polymer, the imidized polymer (B-1) obtained in Synthesis Example 1 was dissolved in a mixed solvent composed of 50 parts by weight of N-methylpyrrolidone and 50 parts by weight of butyl cellosolve, and a solution having a polymer concentration of 3% by weight. I did. This solution was filtered with a filter having a pore size of 0.2 µm to prepare an organic polymer solution for forming an organic film.

[Formation of Organic Film]

On the electrode formation surface of the transparent substrate 1 and the single side | surface of the transparent substrate 2, the said organic polymer solution is apply | coated using a spinner, respectively, prebaking is carried out at 80 degreeC for 1 minute, and then posts at 180 degreeC for 1 hour. By baking, an organic film with an average film thickness of 600 kPa was formed.

From the contact angle of pure water and the contact angle of methylene iodide measured with respect to this organic film, the surface tension calculated | required as follows according to the method described in JOURNAL OF APPLIED POLYMER SCIENCE, VOL.13, PP.1741-1747 (1969) 38 dyne / cm.

4 microliters of water or methylene iodide was dripped on the organic film, and the contact angle after 1 minute passed was measured using the contact angle measuring device "CA-A type" (made by Kyowa Interface Science). The surface tension was calculated by the following formula (3) using numerical values γ ^Sd and γ ^Sp obtained by solving the simultaneous equations of the following formulas (1) and (2):

(1 + cosθ ¹ ) × 72.8 = 2 (γ ^Sd × 21.8) ^1/2 +2 (γ ^Sp × 51.0) ^1/2 (1)

(1 + cosθ ² ) × 50.8 = 2 (γ ^Sd × 49.5) ^1/2 +2 (γ ^Sp × 1.3) ^1/2 (2)

(Theta ¹ is pure water contact angle, and ² is the contact angle of methylene iodide in Formula (1) and (2).).

Surface Tension (Surface Free Energy) γ ^S = γ ^Sd + γ ^Sp (3)

[Production of liquid crystal display device]

The pair of opposing substrates on which the organic films were formed as described above were disposed to face each other with a spacer having a thickness of 10 μm so that the organic film forming surface faced each other, and then the side surfaces were sealed leaving a liquid crystal material injection hole. 1, 2-difluoro-4- [trans-4- (trans-4-n-propylcyclohexyl) cyclohexyl] benzene, 30 weight%, 1,2-difluoro-4- [ 40% by weight of trans-4- (trans-4-n-pentylcyclohexyl) cyclohexyl] benzene and 1,2-difluoro-4- [trans-4- (trans-4-n-heptylcyclohexyl) cyclo After inject | pouring the mixture which consists of hexyl] benzene 30weight%, the liquid crystal material injection port was sealed and the liquid crystal cell was comprised.

And the liquid crystal display device was obtained by sticking a polarizing plate on both surfaces of the said liquid crystal cell, respectively. Here, two polarizing plates were adhere | attached so that the polarization directions might orthogonally cross, and became parallel or perpendicular to the direction of the comb teeth which an electrode has.

[Check the operation of the liquid crystal display]

About the liquid crystal display device manufactured above, the light transmittance at the time of no voltage application, and the light transmittance at the time of applying the voltage of AC 90V were measured. These measured values become an alternative index of the contrast of a liquid crystal display device.

The results are shown in Table 1.

In addition, the light used for the measurement is visible light.

Example 2 and Comparative Example 1

In [Preparation of Organic Polymer Solution] of Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the organic polymers used in Table 1 were used, respectively, and operation confirmation was performed.

The results are shown in Table 1 together with the surface tension of the organic film.

Example 3

Preparation of the organic polymer solution was carried out as follows, except that the organic polymer solution was used, the liquid crystal display device was produced like Example 1, and operation | movement confirmation was performed.

The results are shown in Table 1 together with the surface tension of the organic film.

[Preparation of Organic Polymer Solution]

To the solution containing the polyamic acid (A-1) obtained in the synthesis example 3, the polyorganosiloxane (S-1) obtained in the synthesis example 4, polyamic acid (A-1): polyorganosiloxane (S -1) = 80:20 (weight ratio), and further N-methylpyrrolidone and butyl cellosolve were added and diluted to give a solvent composition of N-methylpyrrolidone: butyl cellosolve = 50:50 (Weight ratio) and the solution of 3 weight% of polymer concentrations were used. The organic polymer solution for organic film formation was prepared by filtering this solution with the filter of 0.2 micrometers of pore diameters.

Claims (7)

A liquid crystal display device which displays by applying an electric field to a liquid crystal substance sandwiched between a pair of transparent substrates,
The liquid crystal material is a liquid crystal material exhibiting a blue phase, and this liquid crystal material is
When the electric field is not applied, it shows optical isotropy, and when the electric field is applied, it shows optical anisotropy, or
When an electric field is not applied, it shows optical anisotropy, when an electric field is applied, it shows optical isotropy, and
An organic film (however, this organic film does not have the ability to orient the liquid crystal material) is formed on a surface of at least one liquid crystal material side of the pair of transparent substrates.
The liquid crystal display device characterized by the above-mentioned. The method of claim 1,
And said organic film comprises at least one organic polymer selected from the group consisting of polyamic acid, imide of polyamic acid, acrylic resin, and polyorganosiloxane. The method of claim 2,
The organic film,
Polyamic acid obtained by making tetracarboxylic acid and the diamine containing at least 1 sort (s) chosen from the group which consists of a diamine which has a fluorene structure, and a diamine which has a 9,10- dihydroanthracene structure,
Imides of the polyamic acid, and
Polyorganosiloxane with Epoxy Group
A liquid crystal display device comprising at least one organic polymer selected from the group consisting of: 4. The method according to any one of claims 1 to 3,
The liquid crystal display device whose surface tension of the said organic film is 40 dyne / cm or less. 4. The method according to any one of claims 1 to 3,
The liquid crystal display device in which the organic film (these organic films do not have the ability to orient the said liquid crystalline material) is formed in the surface on both sides of the liquid crystalline material of the pair of transparent substrates. 4. The method according to any one of claims 1 to 3,
And the direction of the electric field is a direction horizontal to the transparent substrate. 4. The method according to any one of claims 1 to 3,
And a direction in which the electric field is perpendicular to the transparent substrate.

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