WO2019181878A1 - 液晶配向剤、液晶配向膜及び液晶表示素子 - Google Patents
液晶配向剤、液晶配向膜及び液晶表示素子 Download PDFInfo
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- WO2019181878A1 WO2019181878A1 PCT/JP2019/011253 JP2019011253W WO2019181878A1 WO 2019181878 A1 WO2019181878 A1 WO 2019181878A1 JP 2019011253 W JP2019011253 W JP 2019011253W WO 2019181878 A1 WO2019181878 A1 WO 2019181878A1
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- liquid crystal
- formula
- crystal aligning
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- aligning agent
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- 0 CC1=C*(*)C=CC1 Chemical compound CC1=C*(*)C=CC1 0.000 description 8
- MAIGRMJQFNJEPT-UHFFFAOYSA-N CC1C=CC(N(C)c2ccc(C)cc2)=CC1 Chemical compound CC1C=CC(N(C)c2ccc(C)cc2)=CC1 MAIGRMJQFNJEPT-UHFFFAOYSA-N 0.000 description 1
- SKOFWKOHDWVLSW-UHFFFAOYSA-N CC1C=CC(NC2=CCC(CCc(cc3)ccc3N(CC3)CCN3c3ccc(C)cc3)C=C2)=CC1 Chemical compound CC1C=CC(NC2=CCC(CCc(cc3)ccc3N(CC3)CCN3c3ccc(C)cc3)C=C2)=CC1 SKOFWKOHDWVLSW-UHFFFAOYSA-N 0.000 description 1
- BCWKAICXAMOEII-UHFFFAOYSA-N Cc1ccc(COc2ccc(Cc(cc3)ccc3Oc3cc(OC(C(C4C5c(ccc(Oc6ccc(C)cc6)c6)c6O6)C5C6=O)=O)c4cc3)cc2)cc1 Chemical compound Cc1ccc(COc2ccc(Cc(cc3)ccc3Oc3cc(OC(C(C4C5c(ccc(Oc6ccc(C)cc6)c6)c6O6)C5C6=O)=O)c4cc3)cc2)cc1 BCWKAICXAMOEII-UHFFFAOYSA-N 0.000 description 1
- ALQLPWJFHRMHIU-UHFFFAOYSA-N O=C=Nc(cc1)ccc1N=C=O Chemical compound O=C=Nc(cc1)ccc1N=C=O ALQLPWJFHRMHIU-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/54—Silicon-containing compounds
- C08K5/544—Silicon-containing compounds containing nitrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
- C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
Definitions
- the present invention relates to a novel liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element using the same.
- Liquid crystal display elements are widely used as display units for personal computers, mobile phones, smartphones, televisions and the like.
- the liquid crystal display element includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, A thin film transistor (TFT) for switching an electric signal supplied to the pixel electrode is provided.
- TFT thin film transistor
- As a driving method of liquid crystal molecules a vertical electric field method such as a TN method and a VA method, and a horizontal electric field method such as an IPS method and an FFS method are known.
- the horizontal electric field method in which an electrode is formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate is wider than the vertical electric field method in which voltage is applied to the electrodes formed on the upper and lower substrates to drive the liquid crystal. It is known as a liquid crystal display element having viewing angle characteristics and capable of high-quality display.
- the horizontal electric field type liquid crystal cell is excellent in viewing angle characteristics, since there are few electrode portions formed in the substrate, if the voltage holding ratio is low, a sufficient voltage is not applied to the liquid crystal and the display contrast is lowered. Further, if the stability of the liquid crystal alignment is small, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast and an afterimage. Therefore, the stability of the liquid crystal alignment is important. Furthermore, static electricity is likely to be accumulated in the liquid crystal cell, and charges are accumulated in the liquid crystal cell even when a positive / negative asymmetric voltage generated by driving is applied, and these accumulated charges affect the display as a disorder of liquid crystal alignment or an afterimage. The display quality of the liquid crystal element is significantly reduced.
- Patent Document 1 contains a specific diamine and an aliphatic tetracarboxylic acid derivative as a liquid crystal aligning agent that has excellent voltage holding ratio and reduced charge accumulation when used in such a horizontal electric field type liquid crystal display element.
- a liquid crystal aligning agent is disclosed.
- an alignment film having a low volume resistivity as in Patent Document 2 or a volume resistivity as in Patent Document 3 also varies depending on a backlight of a liquid crystal display element.
- a method of using an alignment film that is difficult to perform has been proposed.
- the characteristics required for the liquid crystal alignment film are becoming stricter, and it is difficult to sufficiently satisfy all the required characteristics with these conventional techniques.
- the present invention can provide a liquid crystal alignment film having excellent voltage holding ratio, quick relaxation of accumulated charges, and good liquid crystal alignment and transparency.
- a horizontal electric field type display element such as IPS mode or FFS mode It is an object of the present invention to provide a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element having excellent characteristics.
- the gist of the present invention is a liquid crystal aligning agent containing the following component (A), component (B), and an organic solvent.
- Component (A) at least one polymer selected from the group consisting of a polyimide precursor having the structure of the following formula (2) and an imidized polymer of the polyimide precursor
- R 5 is a single bond or a divalent organic group
- R 6 is a structure represented by — (CH 2 ) n —, and n is an integer of 2 to 20
- Arbitrary —CH 2 — may be replaced with a bond selected from ethers, esters and amides under non-adjacent conditions
- R 7 is a single bond or a divalent organic group, and any hydrogen on the benzene ring
- the atom may be replaced with a monovalent organic group.
- Component (1) Compound represented by the following formula (1)
- Q 1 and Q 2 are each independently one type selected from the following (Q1-1), (Q1-2) and a single bond, but in formula (1), Q 1 And at least one of Q 2 is a kind selected from (Q1-1) and (Q1-2).
- R 1 is a hydrogen atom or a monovalent organic group.
- q1 and q2 are each independently 0 or 1
- L 1 and L 2 are hydrogen atoms.
- S 1 and S 2 are each independently a group represented by the following formula (S).
- R 2 represents a hydrogen atom or an alkyl group
- L represents an alkylene having 2 to 20 carbon atoms
- R 3 and R 4 each independently represents an alkyl group having 1 to 4 carbon atoms, or 2 to 2 carbon atoms.
- 4 is an alkenyl group having 2 to 4 carbon atoms, or q is a natural number having 1 to 3 carbon atoms. * Represents a bond to formula (1).
- liquid crystal aligning agent of the present invention By using the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal aligning film excellent in voltage holding ratio, quickening of accumulated charge, and having good liquid crystal aligning property and transparency, and in particular, IPS.
- a liquid crystal display element having excellent display characteristics in a horizontal electric field type display element such as an FFS system or a FFS system.
- the structure of the compound represented by the said Formula (1) which is the said (B) component contained with the said (A) component has a conjugated structure, for example, liquid crystal aligning film In the inside, it is possible to promote the movement of charges, and to promote the relaxation of accumulated charges.
- (A) component contained in the liquid crystal aligning agent of this invention is at least 1 sort (s) chosen from the group which consists of the polyimide precursor which has a structure represented by following formula (2), and the imidation polymer of this polyimide precursor. (Hereinafter, also referred to as a specific polymer (A)). However, the definition of each symbol in Formula (2) is as described above.
- R 5 is a single bond or a divalent organic group
- R 6 is a structure represented by — (CH 2 ) n —, n is an integer of 2 to 20, and any —CH 2 — It may be replaced with a bond selected from ether, ester and amide under non-adjacent conditions
- R 7 is a single bond or a divalent organic group
- any hydrogen atom on the benzene ring is a monovalent organic group. It may be replaced.
- the divalent organic group constituting R 5 includes a phenyl group (hereinafter referred to as —Ph—), —Ph— (CH 2 ) m — (m is an integer of 1 to 10), —Ph—O.
- R 6 is preferably a single bond or a phenyl group.
- R 7 examples include-(Ph) k- (k is an integer of 1 to 3), -Ph- (CH 2 ) m -Ph- (m is an integer of 1 to 10).
- -Ph- (CH 2 ) 1 -Ph- (CH 2 ) m -Ph- (l and m are each independently an integer of 1 to 10), -Ph-O-Ph-, -Ph-O-C ( ⁇ O) —Ph—, —Ph—C ( ⁇ O) —O—Ph—, —Ph—C ⁇ C—O—Ph— and the like.
- R 7 is preferably a phenyl group or —Ph— (CH 2 ) m —Ph— (m is an integer of 1 to 10).
- N in the formula (2) is preferably an integer of 1 to 10.
- the monovalent organic group of the hydrogen atom of the benzene ring is preferably a group selected from a fluorine atom and a methyl group.
- the polymer obtained using the diamine which has a structure represented by the said Formula (2) is preferable.
- Specific examples of the specific polymer (A) include polyamic acid, polyamic acid ester, and polyimide.
- the specific polymer (A) is, among others, at least one selected from a polyimide precursor containing a structural unit represented by the following formula (3) and a polyimide that is an imidized product thereof. Preferably there is.
- X 3 is a tetravalent organic group derived from the tetracarboxylic acid derivatives. Specifically, at least one selected from the group consisting of structures represented by the following formulas (X1-1) to (X1-45) is preferable.
- R 8 , R 9 , R 10 , and R 11 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, An alkynyl group or a phenyl group. From the viewpoint of liquid crystal orientation, R 8 , R 9 , R 10 , and R 11 are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.
- X 3 is preferably (X1-10), (X1-11), or (X1-29) from the viewpoint of liquid crystal alignment and reliability, and (X1-10) or (X1-11) ) Is more preferable.
- Y 3 is a divalent organic group derived from a diamine containing the structure of Formula (2), and R 7 is a single bond or a benzene ring in Formula (2) from the viewpoint of orientation.
- a divalent organic group derived from is preferable.
- R 13 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and a hydrogen atom or a methyl group is particularly preferable from the viewpoint of ease of imidization by heating.
- the specific polymer (A) in the present invention has a ratio of at least one structural unit selected from the structural unit represented by the above formula (3) and the structural unit obtained by imidizing the structural unit in the specific polymer (A). It is preferably contained in an amount of 20 to 100 mol%, more preferably 30 to 70 mol%, more preferably 50 to 70 mol%, from the viewpoint of achieving both liquid crystal orientation and reliability. Is more preferable.
- the specific polymer (A) in the present invention is further a structural unit represented by the following formula (4) and / or a structural unit obtained by imidizing it. You may have.
- R 14 is the same as the definition of R 13 in the formula (3).
- X 4 is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. Specific examples include the structures of the above formulas (X1-1) to (X-45).
- Y 4 is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of Y 4 include structures of the following formulas (Y-1) to (Y-140).
- the ratio of imidized structural units can be arbitrarily adjusted according to the characteristics of the liquid crystal aligning agent. From the viewpoint of the voltage holding ratio, it is preferable that the imidization ratio in the specific polymer (A) is high. However, when it is excessively high, there is a concern about deterioration of solubility, and therefore the imidation ratio is preferably 40 to 95. %, More preferably 55 to 90%.
- the polyimide precursor used in the present invention is obtained from a reaction between a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acid and polyamic acid ester.
- the polyamic acid which is a polyimide precursor used in the present invention is produced by the following method. Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at ⁇ 20 to 150 ° C., preferably 0 to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 12 hours. Can be manufactured.
- the reaction of the diamine component and the tetracarboxylic acid component is usually performed in an organic solvent.
- the organic solvent used at that time is not particularly limited as long as the produced polyimide precursor is dissolved. Although the specific example of the organic solvent used for reaction below is given, it is not limited to these examples. Examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or ⁇ -butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-imidazolidinone. It is done.
- the solubility of the polyimide precursor is high, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formulas [D-1] to [D-3].
- An organic solvent can be used.
- D 1 represents an alkyl group having 1 to 3 carbon atoms
- D-2 represents an alkyl group having 1 to 3 carbon atoms
- D 3 represents an alkyl group having 1 to 4 carbon atoms.
- organic solvents may be used alone or in combination. Furthermore, even if it is a solvent which does not melt
- the concentration of the polyamic acid polymer in the reaction system is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight product is easily obtained.
- the polyamic acid obtained as described above can be recovered by precipitating the polymer by pouring into the poor solvent while thoroughly stirring the reaction solution. In addition, by performing precipitation several times, washing with a poor solvent, and then drying at normal temperature or heat, a purified polyamic acid powder can be obtained.
- a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.
- the polyamic acid ester which is a polyimide precursor used in the present invention can be produced by the following production method (1), (2) or (3).
- a polyamic acid ester can be manufactured by esterifying a polyamic acid. Specifically, it is produced by reacting a polyamic acid and an esterifying agent in the presence of an organic solvent at ⁇ 20 to 150 ° C., preferably 0 to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 4 hours. can do.
- the esterifying agent is preferably one that can be easily removed by purification.
- the addition amount of the esterifying agent is preferably 2 to 6 molar equivalents per 1 mol of the polyamic acid repeating unit.
- organic solvent examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or ⁇ -butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl- Examples include imidazolidinone.
- solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the above formulas [D-1] to [D-3]
- the indicated organic solvents can be used.
- organic solvents may be used alone or in combination. Furthermore, even if it is a solvent which does not dissolve a polyimide precursor, you may mix and use it for the said solvent in the range which the produced
- the solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or ⁇ -butyrolactone from the solubility of the polymer. These may be used alone or in combination of two or more. Also good.
- the concentration at the time of production is preferably 1 to 30% by mass and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight product is easily obtained.
- the polyamic acid ester can be manufactured from tetracarboxylic acid diester dichloride and diamine. Specifically, tetracarboxylic acid diester dichloride and diamine are mixed in the presence of a base and an organic solvent at ⁇ 20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 4 hours. It can be produced by reacting.
- pyridine triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently.
- the addition amount of the base is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.
- the organic solvent is preferably N-methyl-2-pyrrolidone or ⁇ -butyrolactone in view of the solubility of the monomer and polymer, and these may be used alone or in combination.
- the polymer concentration at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight product is easily obtained.
- the organic solvent used for the production of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.
- Polyamic acid ester can be manufactured by polycondensing tetracarboxylic-acid diester and diamine. Specifically, a tetracarboxylic acid diester and a diamine are mixed in the presence of a condensing agent, a base, and an organic solvent at 0 to 150 ° C., preferably 0 to 100 ° C., for 30 minutes to 24 hours, preferably 3 to It can be produced by reacting for 15 hours.
- the condensing agent examples include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazi Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like.
- the addition amount of the condensing agent is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester
- tertiary amines such as pyridine and triethylamine can be used.
- the amount of the base added is preferably 2 to 4 times the mol of the diamine component from the viewpoint that it can be easily removed and a high molecular weight product can be easily obtained.
- the reaction proceeds efficiently by adding a Lewis acid as an additive.
- the Lewis acid lithium halides such as lithium chloride and lithium bromide are preferable.
- the addition amount of the Lewis acid is preferably 0 to 1.0 times mol with respect to the diamine component.
- the production method (1) or (2) is particularly preferable.
- the polyamic acid ester solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyamic acid ester powder.
- a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.
- the polyimide (imidized polymer in the component (A)) used in the present invention can be produced by imidizing the above polyamic acid ester or polyamic acid.
- a polyimide is produced from a polyamic acid
- chemical imidization in which a catalyst is added to the polyamic acid solution obtained by the reaction of the diamine component and tetracarboxylic dianhydride and reacted is simple.
- the chemical imidation is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is hardly lowered during the imidization process.
- Chemical imidation can be performed by stirring the polyamic acid to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride.
- an organic solvent the organic solvent used at the time of the polymerization reaction mentioned above can be used.
- Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Among these, pyridine is preferable because it has a basicity appropriate for advancing the reaction.
- Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among these, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated.
- the temperature for carrying out the imidization reaction is ⁇ 20 to 140 ° C., preferably 0 to 100 ° C., and the reaction time is 0.5 to 100 hours, preferably 1 to 80 hours.
- the amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times that of the amic acid, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times that of the amic acid. Is double.
- the imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.
- the added catalyst and the like remain, so the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent.
- it is preferably used as the component (A) of the liquid crystal aligning agent of the present invention.
- the polyimide solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyimide powder.
- the poor solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.
- ⁇ (B) component> (B) component contained in the liquid crystal aligning agent of this invention is a compound represented by following formula (1).
- the monovalent organic group in the formula (Q1-1) and the formula (Q1-2) is preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.
- L 1 and L 2 are hydrogen atoms.
- Q 1 is (Q1-1)
- L 1 and L 2 together form a single bond, for example, as in the compound represented by the following formula B-5-1 Also good.
- S 1 and S 2 are each independently a group represented by the following formula (S).
- R 2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms
- L represents an alkylene having 2 to 20 carbon atoms
- R 3 and R 4 each independently represents an alkyl having 1 to 4 carbon atoms.
- q represents a natural number of 1 to 3. * Represents a bond to formula (1).
- the monovalent organic group for R 1 is more preferably a methyl group, a phenyl group, or a thermally decomposable leaving group.
- the thermally decomposable leaving group is a substituent that is removed by heating and replaced with a hydrogen atom.
- a thermally decomposable leaving group is an amino-protecting group, and its structure is not particularly limited as long as it is a functional group that can be replaced by a hydrogen atom by heat.
- this protecting group D is preferably not desorbed at room temperature, preferably a protecting group desorbed by heat of 80 ° C. or higher, more preferably 100 ° C. or higher. It is a protecting group that is removed by heat. From the viewpoint of elimination temperature, D is particularly preferably a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group.
- Preferable examples of the compound represented by component (B) include the following compounds (B-1) to (B-9).
- B-1) a compound in which q1 and q2 are 0 in the above formula (1), Q 1 is (Q1-1), and L 1 and L 2 are hydrogen atoms
- B-2) In the above formula (1), q1 and q2 are 0, a Q 1 is (Q1-1), the compound L 1 and L 2 is a single bond together
- B-4) In the above formula (1), a q1 and q2 is 1, a Q 1 is (Q1-1), Q 2 is a single bond, L 1 and L 2 are hydrogen atoms Compound, (B-5): In the above formula (1), a q1 and q2 is 1, a Q 1 is (Q1-1),
- Preferable specific examples of the compound represented by component (B) include at least one selected from the group consisting of compounds represented by the following formulas B-1-1 to B-9-1.
- the compound of the component (B) in the present invention can be obtained by reacting a diamine represented by the following formula (0) with trialkoxysilylpropyl isocyanate by a known method.
- Q 1 , Q 2 , L 1 , L 2 , q1 and q2 in the formula (0) are the same as defined in the above formula (1).
- Known diamines represented by the formula (0) may be used.
- the amount of the isocyanate compound used is preferably 0.98 to 1.2 equivalent times the amino group, more preferably 1.0 to 1.05. Equivalent times.
- the reaction solvent is not particularly limited as long as it is inert to the reaction.
- hydrocarbons such as hexane, cyclohexane, benzene and toluene; halogenated hydrocarbons such as carbon tetrachloride, chloroform and 1,2-dichloroethane; ethers such as diethyl ether, diisopropyl ether, 1,4-dioxane and tetrahydrofuran Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; nitriles such as acetonitrile and propionitrile; carboxylic acid esters such as ethyl acetate and ethyl propionate; N, N-dimethylformamide and N, N-dimethylacetamide Nitrogen-containing aprotic polar solvents such as N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazo
- solvents may be used alone or in combination of two or more thereof.
- Preferred are toluene, acetonitrile, ethyl acetate and tetrahydrofuran, and more preferred are acetonitrile and tetrahydrofuran.
- the amount of the solvent used is not particularly limited, but the reaction may be carried out without using a solvent.
- the solvent is used in an amount of 0.1 to 100 times the amount of the isocyanate compound. It may be used.
- the amount is preferably 0.5 to 30 times by mass, more preferably 1 to 10 times by mass.
- the reaction temperature is not particularly limited, but is, for example, ⁇ 90 ° C. to 150 ° C., preferably ⁇ 30 ° C. to 100 ° C., and more preferably 0 ° C. to 80 ° C.
- the reaction time is usually 1 minute to 200 hours, preferably 30 minutes to 100 hours.
- the addition amount of the component (B) is preferably 0.1 to 20% by mass and more preferably 1 to 10% by mass with respect to the component (A) (100% by mass).
- the liquid crystal aligning agent used in the present invention is a solution in which the compound represented by the formula (1) which is the specific polymer (A) and the component (B) as the component (A) is dissolved in an organic solvent. It has a form.
- the molecular weight of the specific structure polymer (A) is preferably 2,000 to 500,000 in weight average molecular weight, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000. is there.
- the number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.
- the concentration of the specific polymer (A) of the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film.
- the amount is preferably 1% by weight or more, and preferably 10% by weight or less from the viewpoint of storage stability of the solution, and more preferably 1 to 5% by weight.
- the organic solvent contained in the liquid crystal aligning agent used in the present invention is preferably a good solvent in which the specific polymer (A) is uniformly dissolved.
- organic solvent examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, ⁇ -butyrolactone, 1,3-dimethyl- Examples thereof include imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and 4-hydroxy-4-methyl-2-pentanone.
- N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and ⁇ -butyrolactone are preferably used as the organic solvent.
- the good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass of the whole solvent contained in the liquid crystal aligning agent. Of these, 20 to 90% by mass is preferable. More preferred is 30 to 80% by mass. We suggest deletion for consistency with paragraph 0077.
- the liquid crystal aligning agent of this invention can use the solvent (it is also called a poor solvent) which improves the coating property and surface smoothness of a liquid crystal aligning film at the time of apply
- a poor solvent is given to the following, it is not limited to these examples.
- ethanol isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2- Etanji 1,2-propanediol, 1,3-propaned
- 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether are preferable.
- These poor solvents are preferably 1 to 80% by mass of the whole solvent contained in the liquid crystal aligning agent. Of these, 10 to 80% by mass is preferable. More preferred is 20 to 70% by mass.
- the liquid crystal aligning agent of the present invention includes a polymer other than the polymer described in the present invention, a dielectric or conductive material for changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, and liquid crystal Silane coupling agent for the purpose of improving the adhesion between the alignment film and the substrate, a crosslinkable compound for the purpose of increasing the hardness and density of the liquid crystal alignment film, and a polyimide precursor when the coating film is baked
- An imidization accelerator for the purpose of efficiently proceeding imidization by heating the body may be added.
- the liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal aligning agent to a substrate, drying and baking.
- the substrate on which the liquid crystal aligning agent of the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a polycarbonate substrate such as a polycarbonate substrate, or the like can be used. From the viewpoint of simplification of the process, it is preferable to use a substrate on which an ITO electrode or the like is formed.
- an opaque material such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light, such as aluminum, can also be used.
- Examples of the method for applying the liquid crystal aligning agent of the present invention include a spin coating method, a printing method, and an ink jet method.
- Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent of the present invention.
- the organic solvent contained is dried at 50 to 120 ° C. for 1 to 10 minutes and then baked at 150 to 300 ° C. for 5 to 120 minutes.
- the thickness of the coating film after baking is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, and therefore it is 5 to 300 nm, preferably 10 to 200 nm.
- Examples of a method for aligning the obtained liquid crystal alignment film include a rubbing method and a photo-alignment processing method.
- the rubbing process can be performed using an existing rubbing apparatus.
- Examples of the material of the rubbing cloth at this time include cotton, nylon, and rayon.
- As the conditions for rubbing treatment generally, conditions of a rotational speed of 300 to 2000 rpm, a feed speed of 5 to 100 mm / s, and an indentation amount of 0.1 to 1.0 mm are used. Thereafter, the residue generated by rubbing is removed by ultrasonic cleaning using pure water or alcohol.
- the photo-alignment treatment method there is a method of imparting liquid crystal alignment ability by irradiating the coating film surface with radiation deflected in a certain direction, and further subjecting to a temperature of 150 to 250 ° C. in some cases.
- the radiation ultraviolet rays and visible rays having a wavelength of 100 to 800 nm can be used. Of these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable.
- radiation may be irradiated while heating the coated substrate at 50 to 250 ° C.
- Dose of the radiation is preferably 1 ⁇ 10,000mJ / cm 2, particularly preferably 100 ⁇ 5,000mJ / cm 2.
- the liquid crystal alignment film produced as described above can stably align liquid crystal molecules in a certain direction.
- a higher extinction ratio of polarized ultraviolet rays is preferable because higher anisotropy can be imparted.
- the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, and more preferably 20: 1 or more.
- the film irradiated with polarized radiation may then be contact-treated with a solvent containing at least one selected from water and an organic solvent.
- the solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves a decomposition product generated by light irradiation.
- Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, 3- Examples include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Two or more of these solvents may be used in combination.
- At least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate is more preferable.
- Water, 2-propanol, and a mixed solvent of water and 2-propanol are particularly preferable.
- the contact treatment between the film irradiated with polarized radiation and the solution containing the organic solvent is a treatment such that the film and the liquid are preferably sufficiently in contact with each other, such as immersion treatment or spraying treatment.
- a method of immersing the film in a solution containing an organic solvent preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferable.
- the contact treatment may be performed at normal temperature or preferably at 10 to 80 ° C., more preferably 20 to 50 ° C.
- a means for enhancing contact such as ultrasonic waves can be applied as necessary.
- rinsing with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or drying, or both May be done.
- a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or drying, or both May be done.
- the film subjected to the contact treatment with the solvent may be heated at 150 ° C. or higher for the purpose of drying the solvent and reorienting the molecular chains in the film.
- the heating temperature is preferably 150 to 300 ° C. A higher temperature promotes reorientation of molecular chains. However, if the temperature is too high, molecular chains may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 ° C., and particularly preferably 200 to 230 ° C. If the heating time is too short, the effect of reorientation of the molecular chain may not be obtained, and if it is too long, the molecular chain may be decomposed, and is preferably 10 seconds to 30 minutes. More preferred is ⁇ 10 minutes.
- the liquid crystal display element of this invention comprises the liquid crystal aligning film obtained by the manufacturing method of the said liquid crystal aligning film.
- a liquid crystal cell is produced by a known method, and a liquid crystal cell is used. This is a display element.
- a liquid crystal display element having a passive matrix structure As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Note that an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.
- a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate.
- These electrodes can be ITO electrodes, for example, and are patterned so as to display a desired image.
- an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode.
- the insulating film can be, for example, a film made of SiO 2 —TiO 2 formed by a sol-gel method.
- the liquid crystal alignment film of the present invention is formed on each substrate.
- the other substrate is superposed on one substrate so that the alignment film surfaces face each other, and the periphery is bonded with a sealant.
- a spacer is usually mixed in the sealing material.
- spacers for controlling the substrate gap are also sprayed on the in-plane portion where no sealing material is provided. A part of the sealing material is provided with an opening that can be filled with liquid crystal from the outside.
- a liquid crystal material is injected into a space surrounded by two substrates and the sealing material through an opening provided in the sealing material. Thereafter, the opening is sealed with an adhesive.
- a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used.
- a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surfaces of the two substrates opposite to the liquid crystal layer.
- the sealant for example, a resin that is cured by ultraviolet irradiation or heating having a reactive group such as an epoxy group, an acryloyl group, a methacryloyl group, a hydroxyl group, an allyl group, or an acetyl group is used.
- a cured resin system having reactive groups of both an epoxy group and a (meth) acryloyl group is preferable.
- An inorganic filler may be blended in the sealing agent of the present invention for the purpose of improving adhesiveness and moisture resistance.
- the inorganic filler that can be used is not particularly limited.
- spherical silica, fused silica, crystalline silica titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, oxidation
- examples thereof include magnesium, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, and asbestos.
- spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, or silicic acid Aluminum is preferred.
- Two or more inorganic fillers may be mixed and used.
- ⁇ Viscosity> The viscosity of the polymer solution in the following synthesis example was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), a sample amount of 1.1 mL, cone rotor TE-1 (1 ° 34 ′, R24), temperature 25 Measured at ° C.
- * 1 Indicates the content (parts by weight) of each polymer relative to 100 parts by weight of the total polymer in the liquid crystal aligning agent.
- * 2 Indicates the content (parts by weight) of each additive relative to 100 parts by weight of the total polymer in the liquid crystal alignment agent.
- * 3 Indicates the content (parts by weight) of each solvent relative to 100 parts by mass of the liquid crystal aligning agent.
- a method for manufacturing a liquid crystal cell for evaluating the stored charge relaxation characteristics, flicker characteristics, and liquid crystal alignment is described below.
- a liquid crystal cell having a configuration of an FFS liquid crystal display element is manufactured.
- a substrate with electrodes was prepared.
- the substrate is a glass substrate having a length of 30 mm, a width of 35 mm, and a thickness of 0.7 mm.
- an IZO electrode constituting the counter electrode as the first layer is formed on the entire surface.
- a SiN (silicon nitride) film formed by the CVD method is formed as the second layer.
- the second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film.
- a comb-like pixel electrode formed by patterning an IZO film is arranged as a third layer on the second layer SiN film to form two pixels, a first pixel and a second pixel. is doing.
- the size of each pixel is 10 mm long and about 5 mm wide.
- the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.
- the pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of “U” -shaped electrode elements having a bent central portion.
- the width in the short direction of each electrode element is 3 ⁇ m, and the distance between the electrode elements is 6 ⁇ m.
- the pixel electrode that forms each pixel is formed by arranging a plurality of "bow" -shaped electrode elements that are bent at the center, so that the shape of each pixel is not rectangular and is similar to the electrode elements Bold at the center, it has a bold shape resembling a “Kugi”.
- Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.
- the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film to be described later is used as a reference, in the first region of the pixel, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise), and in the second region of the pixel The electrode elements of the pixel electrode are formed at an angle of ⁇ 10 ° (clockwise).
- the direction of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode in the substrate plane is It is comprised so that it may become a mutually reverse direction.
- liquid crystal aligning agents obtained in Examples and Comparative Examples were filtered through a filter having a pore diameter of 1.0 ⁇ m, and then applied to the prepared substrate with electrodes by spin coating. After drying on an 80 ° C. hot plate for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C. for 20 minutes to obtain a polyimide film having a thickness of 60 nm.
- This polyimide film is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation length: 0.3 mm, rubbing direction: inclined by 10 ° with respect to the third-layer IZO comb-teeth electrode Then, ultrasonic cleaning was performed for 1 minute in pure water for cleaning, and water droplets were removed by air blow. Then, it dried for 15 minutes at 80 degreeC, and obtained the board
- a substrate with a liquid crystal alignment film was obtained.
- One set of these two substrates with a liquid crystal alignment film is printed, and the sealant is printed on the substrate leaving the liquid crystal injection port.
- the other substrate has the liquid crystal alignment film surface facing and the rubbing direction is antiparallel. They were pasted together.
- the sealing agent was cured to produce an empty cell having a cell gap of 4 ⁇ m.
- Liquid crystal MLC-3019 manufactured by Merck & Co., Inc.
- was injected into this empty cell by a reduced pressure injection method was sealed to obtain an FFS liquid crystal cell.
- the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand at 23 ° C. overnight, and then used for evaluation of liquid crystal alignment.
- the liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the pixel electrode and the counter electrode are short-circuited to be at the same potential, and the LED is displayed from under the two polarizing plates.
- the angle of the liquid crystal cell was adjusted so that the brightness of the LED backlight transmitted light measured on the two polarizing plates was minimized by irradiating the backlight.
- the VT characteristics voltage-transmittance characteristics
- this AC voltage corresponds to a region where the change in luminance with respect to the voltage is large, it is convenient to evaluate the accumulated charge via the luminance.
- a rectangular wave having a relative transmittance of 23% at a temperature of 23 ° C. and a frequency of 30 Hz was applied for 5 minutes, and then a +1.0 V DC voltage was superimposed and driven for 30 minutes. Thereafter, the DC voltage was turned off, and only a rectangular wave with an AC voltage that gave a relative transmittance of 23% and a frequency of 30 Hz was applied for 15 minutes. The faster the accumulated charge is relaxed, the faster the charge is accumulated in the liquid crystal cell when the DC voltage is superimposed.
- the relaxation characteristic of the accumulated charge is reduced by 2% or more from the relative transmittance immediately after the DC voltage is superimposed. Evaluation was made based on the time required until. That is, when the relative transmittance was reduced by 2% or more within 30 minutes, it was defined as “good”, and when the relative decrease rate was not decreased by 2% or more after 30 minutes, it was defined as “bad”.
- the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel became darkest to the angle at which the first region became darkest was calculated as an angle ⁇ .
- the second area was compared with the first area, and a similar angle ⁇ was calculated.
- the average value of the angle ⁇ values of the first pixel and the second pixel was calculated as the angle ⁇ of the liquid crystal cell.
- VHR voltage holding ratio
- UV-3600 manufactured by Shimadzu Corporation
- the transmittance was measured under the conditions of a temperature of 25 ° C. and a scan wavelength of 300 to 800 nm. In that case, it performed using the quartz substrate which has not apply
- the average transmittance at a wavelength of 400 to 800 nm was calculated, and the higher the transmittance, the better the transparency.
- * 1 Indicates the content (parts by weight) of each polymer relative to 100 parts by weight of the total polymer in the liquid crystal aligning agent.
- * 2 Indicates the content (parts by weight) of each additive relative to 100 parts by weight of the total polymer in the liquid crystal alignment agent.
- the liquid crystal display elements using the liquid crystal aligning agents of Examples 1 to 3 have excellent voltage holding ratio, fast relaxation of accumulated charges, and good liquid crystal alignment and transparency. I understand.
- the liquid crystal aligning agent of the present invention is widely used for a liquid crystal display element of a vertical electric field method such as a TN method or a VA method, particularly a horizontal electric field method such as an IPS method or an FFS method.
- a vertical electric field method such as a TN method or a VA method
- a horizontal electric field method such as an IPS method or an FFS method.
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Abstract
Description
すなわち、本発明は、下記の(A)成分、(B)成分、及び有機溶媒を含有することを特徴とする液晶配向剤を要旨とする。
(A)成分:下記式(2)の構造を有するポリイミド前駆体、該ポリイミド前駆体のイミド化重合体からなる群から選ばれる少なくとも1種の重合体
(B)成分:下記式(1)で表される化合物
L1及びL2は水素原子である。但し、Q1が(Q1-1)である場合は、L1及びL2は一緒になって単結合を形成していてもよい。
S1及びS2はそれぞれ独立に下記式(S)で表される基である。
式中、R2は水素原子、又はアルキル基を表し、Lは炭素数2~20のアルキレンを表し、R3及びR4は、それぞれ独立に炭素数1~4のアルキル基、炭素数2~4のアルケニル基、又は炭素数2~4のアルキニル基であり、qは1~3の自然数を表す。*は式(1)への結合を表す。
本発明の液晶配向剤に含まれる(A)成分は、下記式(2)で表される構造を有するポリイミド前駆体、及び該ポリイミド前駆体のイミド化重合体からなる群から選ばれる少なくとも1種の重合体(以下、特定重合体(A)ともいう)である。
R5は単結合又は2価の有機基であり、R6は-(CH2)n-で表される構造であり、nは2~20の整数であり、任意の-CH2-はそれぞれ隣り合わない条件でエーテル、エステル及びアミドから選ばれる結合に置き換えられてもよく、R7は単結合又は2価の有機基であり、ベンゼン環上の任意の水素原子は1価の有機基で置き換えられてもよい。
なお、R5を構成する2価の有機基としては、フェニル基(以下、-Ph-と表記)、-Ph-(CH2)m-(mは1~10の整数)、-Ph-O-、-Ph-O-C(=O)-、-Ph-C(=O)-O-、-Ph-C=C-O-などが挙げられる。R6は、なかでも、単結合又はフェニル基が好ましい。
また、R7構成する2価の有機基としては、-(Ph)k-(kは1~3の整数)、-Ph-(CH2)m-Ph-(mは1~10の整数)、-Ph-(CH2)l-Ph-(CH2)m-Ph-(l、mはそれぞれ独立に1~10の整数)、-Ph-O-Ph-、-Ph-O-C(=O)-Ph-、-Ph-C(=O)-O-Ph-、-Ph-C=C-O-Ph-などが挙げられる。R7は、なかでも、フェニル基又は-Ph-(CH2)m-Ph-(mは1~10の整数)が好ましい。
式(2)におけるnは1~10の整数であるのが好ましい。また、ベンゼン環の水素原子の1価の有機基は、フッ素原子及びメチル基から選ばれる基が好ましい。
但し、式(4)において、R14は、前記式(3)のR13の定義と同じである。X4はテトラカルボン酸誘導体に由来する4価の有機基であり、その構造は特に限定されない。具体的例を挙げるならば、上記式(X1-1)~(X-45)の構造が挙げられる。
<ポリイミド前駆体(ポリアミック酸)>
本発明に用いられるポリイミド前駆体であるポリアミック酸は、以下の方法により製造される。具体的には、テトラカルボン酸二無水物とジアミンとを、有機溶媒の存在下で、-20~150℃、好ましくは0~50℃において、30分~24時間、好ましくは1~12時間反応させることによって製造できる。
また、ポリイミド前駆体の溶解性が高い場合は、メチルエチルケトン、シクロヘキサノン、シクロペンタノン、4-ヒドロキシ-4-メチル-2-ペンタノン又は下記の式[D-1]~式[D-3]で示される有機溶媒を用いることができる。
本発明に用いられるポリイミド前駆体であるポリアミック酸エステルは、以下に示す(1)、(2)又は(3)の製法で製造することができる。
ポリアミック酸エステルは、ポリアミック酸をエステル化することによって製造できる。具体的には、ポリアミック酸とエステル化剤を有機溶媒の存在下で、-20~150℃、好ましくは0~50℃において、30分~24時間、好ましくは1~4時間反応させることによって製造することができる。
上記の反応に用いる溶媒は、ポリマーの溶解性から、N,N-ジメチルホルムアミド、N-メチル-2-ピロリドン、又はγ-ブチロラクトンが好ましく、これらは1種又は2種以上を混合して用いてもよい。製造時の濃度は、ポリマーの析出が起こりにくく、かつ高分子量体が得やすいという点から、1~30質量%が好ましく、5~20質量%がより好ましい。
ポリアミック酸エステルは、テトラカルボン酸ジエステルジクロリドとジアミンから製造することができる。具体的には、テトラカルボン酸ジエステルジクロリドとジアミンとを、塩基と有機溶媒の存在下で、-20~150℃、好ましくは0~50℃において、30分~24時間、好ましくは1~4時間反応させることによって製造することができる。
製造時のポリマー濃度は、ポリマーの析出が起こりにくく、かつ高分子量体が得やすいという点から、1~30質量%が好ましく、5~20質量%がより好ましい。また、テトラカルボン酸ジエステルジクロリドの加水分解を防ぐため、ポリアミック酸エステルの製造に用いる有機溶媒は、できるだけ脱水されていることが好ましく、窒素雰囲気中で、外気の混入を防ぐのが好ましい。
ポリアミック酸エステルは、テトラカルボン酸ジエステルとジアミンを重縮合することにより製造することができる。具体的には、テトラカルボン酸ジエステルとジアミンとを、縮合剤、塩基、及び有機溶媒の存在下で、0~150℃、好ましくは0~100℃において、30分~24時間、好ましくは3~15時間反応させることによって製造できる。
また、上記反応において、ルイス酸を添加剤として加えることで、反応が効率的に進行する。ルイス酸としては、塩化リチウム、臭化リチウムなどのハロゲン化リチウムが好ましい。ルイス酸の添加量はジアミン成分に対して0~1.0倍モルが好ましい。
上記のようにして得られるポリアミック酸エステルの溶液は、よく撹拌させながら貧溶媒に注入することで、ポリマーを析出させることができる。析出を数回行い、貧溶媒で洗浄後、常温あるいは加熱乾燥して、精製されたポリアミック酸エステルの粉末を得ることができる。貧溶媒は、特に限定されないが、水、メタノール、エタノール、ヘキサン、ブチルセロソルブ、アセトン、トルエン等が挙げられる。
本発明に用いられるポリイミド((A)成分におけるイミド化重合体)は、前記したポリアミック酸エステル又はポリアミック酸をイミド化することにより製造できる。
化学的イミド化は、イミド化させたいポリアミック酸を、有機溶媒中、塩基性触媒と酸無水物の存在下で、攪拌することにより行うことができる。有機溶媒としては、前述した重合反応時に用いる有機溶媒を使用することができる。塩基性触媒としては、ピリジン、トリエチルアミン、トリメチルアミン、トリブチルアミン、トリオクチルアミン等を挙げることができる。中でも、ピリジンは、反応を進行させるのに適度な塩基性を持つので好ましい。また、酸無水物としては、無水酢酸、無水トリメリット酸、無水ピロメリット酸等を挙げることができ、中でも、無水酢酸を用いると、反応終了後の精製が容易となるので好ましい。
上記のようにして得られるポリイミドの溶液は、よく撹拌させながら貧溶媒に注入することで、重合体を析出させることができる。析出を数回行い、貧溶媒で洗浄後、常温あるいは加熱乾燥して、精製されたポリイミドの粉末を得ることができる。
前記貧溶媒は、特に限定されないが、メタノール、アセトン、ヘキサン、ブチルセルソルブ、ヘプタン、メチルエチルケトン、メチルイソブチルケトン、エタノール、トルエン、ベンゼン等が挙げられる。
本発明の液晶配向剤に含有される(B)成分は下記式(1)で表される化合物である。
また、式(Q1-1)及び式(Q1-2)における一価の有機基は、炭素数1~3のアルキル基であるのが好ましく、特に、メチル基が好ましい。
L1及びL2は水素原子である。但し、Q1が(Q1-1)である場合は、例えば、後記式B-5-1で表される化合物のように、L1及びL2は一緒になって単結合を形成していてもよい。
S1及びS2はそれぞれ独立に下記式(S)で表される基である。
式中、R2は水素原子、又は炭素数1~4のアルキル基を表し、Lは炭素数2~20のアルキレンを表し、R3及びR4は、それぞれ独立に炭素数1~4のアルキル基、炭素数2~4のアルケニル基、又は炭素数2~4のアルキニル基であり、qは1~3の自然数を表す。*は式(1)への結合を表す。
(B-1):上記式(1)において、q1及びq2が0であり、Q1が(Q1-1)であり、L1及びL2が水素原子である化合物、
(B-2):上記式(1)において、q1及びq2が0であり、Q1が(Q1-1)であり、L1及びL2が一緒になって単結合である化合物、
(B-3):上記式(1)において、q1及びq2が1であり、Q1が(Q1-1)であり、Q2が(Q1-1)であり、L1及びL2が水素原子である化合物、
(B-4):上記式(1)において、q1及びq2が1であり、Q1が(Q1-1)であり、Q2が単結合であり、L1及びL2が水素原子である化合物、
(B-5):上記式(1)において、q1及びq2が1であり、Q1が(Q1-1)であり、Q2が(Q1-1)であり、L1及びL2が一緒になって単結合である化合物、
(B-6):上記式(1)において、q1及びq2が1であり、Q1が単結合であり、Q2が(Q1-1)であり、L1及びL2が水素原子である化合物、
(B-7):上記式(1)において、q1及びq2が1であり、Q1が(Q1-1)であり、Q2が単結合であり、L1及びL2が一緒になって単結合である化合物、
(B-8):上記式(1)において、q1及びq2が0であり、Q1が(Q1-2)であり、L1及びL2が水素原子である化合物。
(B-9):上記式(1)において、q1及びq2が1であり、Q1が(Q1-2)であり、L1及びL2が水素原子である化合物。
本発明に用いられる液晶配向剤は、前記した(A)成分である特定重合体(A)及び(B)成分である式(1)で表される化合物が有機溶媒中に溶解された溶液の形態を有する。特定構造重合体(A)の分子量は、重量平均分子量で2,000~500,000が好ましく、より好ましくは5,000~300,000であり、さらに好ましくは、10,000~100,000である。また、数平均分子量は、好ましくは、1,000~250,000であり、より好ましくは、2,500~150,000であり、さらに好ましくは、5,000~50,000である。
本発明に用いられる液晶配向剤に含有される有機溶媒は、特定重合体(A)が均一に溶解する良溶媒あるのが好ましい。
有機溶媒としては、例えば、N,N-ジメチルホルムアミド、N,N-ジメチルアセトアミド、N-メチル-2-ピロリドン、N-エチル-2-ピロリドン、ジメチルスルホキシド、γ-ブチロラクトン、1,3-ジメチル-イミダゾリジノン、メチルエチルケトン、シクロヘキサノン、シクロペンタノン、又は4-ヒドロキシ-4-メチル-2-ペンタノンなどを挙げることができる。
さらに、本発明の重合体の溶媒への溶解性が高い場合は、前記式[D-1]~式[D-3]で示される溶媒を用いることが好ましい。
本発明の液晶配向剤における良溶媒は、液晶配向剤に含まれる溶媒全体の20~99質量%であることが好ましい。なかでも、20~90質量%が好ましい。より好ましいのは、30~80質量%である。
段落0077などとの整合性から削除を提案します。
例えば、エタノール、イソプロピルアルコール、1-ブタノール、2-ブタノール、イソブチルアルコール、tert-ブチルアルコール、1-ペンタノール、2-ペンタノール、3-ペンタノール、2-メチル-1-ブタノール、イソペンチルアルコール、tert-ペンチルアルコール、3-メチル-2-ブタノール、ネオペンチルアルコール、1-ヘキサノール、2-メチル-1-ペンタノール、2-メチル-2-ペンタノール、2-エチル-1-ブタノール、1-ヘプタノール、2-ヘプタノール、3-ヘプタノール、1-オクタノール、2-オクタノール、2-エチル-1-ヘキサノール、シクロヘキサノール、1-メチルシクロヘキサノール、2-メチルシクロヘキサノール、3-メチルシクロヘキサノール、1,2-エタンジオール、1,2-プロパンジオール、1,3-プロパンジオール、1,2-ブタンジオール、1,3-ブタンジオール、1,4-ブタンジオール、2,3-ブタンジオール、1,5-ペンタンジオール、2-メチル-2,4-ペンタンジオール、2-エチル-1,3-ヘキサンジオール、ジプロピルエーテル、ジブチルエーテル、ジヘキシルエーテル、ジオキサン、エチレングリコールジメチルエーテル、エチレングリコールジエチルエーテル、エチレングリコールジブチルエーテル、1,2-ブトキシエタン、ジエチレングリコールジメチルエーテル、ジエチレングリコールジエチルエーテル、ジエチレングリコールメチルエチルエーテル、ジエチレングリコールジブチルエーテル、2-ペンタノン、3-ペンタノン、2-ヘキサノン、2-ヘプタノン、4-ヘプタノン、3-エトキシブチルアセタート、1-メチルペンチルアセタート、2-エチルブチルアセタート、2-エチルヘキシルアセタート、エチレングリコールモノアセタート、エチレングリコールジアセタート、プロピレンカーボネート、エチレンカーボネート、2-(メトキシメトキシ)エタノール、エチレングリコールモノブチルエーテル、エチレングリコールモノイソアミルエーテル、エチレングリコールモノヘキシルエーテル、2-(ヘキシルオキシ)エタノール、フルフリルアルコール、ジエチレングリコール、プロピレングリコール、プロピレングリコールモノブチルエーテル、1-(ブトキシエトキシ)プロパノール、プロピレングリコールモノメチルエーテルアセタート、ジプロピレングリコール、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノエチルエーテル、ジプロピレングリコールジメチルエーテル、トリプロピレングリコールモノメチルエーテル、エチレングリコールモノメチルエーテルアセタート、エチレングリコールモノエチルエーテルアセタート、エチレングリコールモノブチルエーテルアセタート、エチレングリコールモノアセタート、エチレングリコールジアセタート、ジエチレングリコールモノエチルエーテルアセタート、ジエチレングリコールモノブチルエーテルアセタート、2-(2-エトキシエトキシ)エチルアセタート、ジエチレングリコールアセタート、トリエチレングリコール、トリエチレングリコールモノメチルエーテル、トリエチレングリコールモノエチルエーテル、乳酸メチル、乳酸エチル、酢酸メチル、酢酸エチル、酢酸n-ブチル、酢酸プロピレングリコールモノエチルエーテル、ピルビン酸メチル、ピルビン酸エチル、3-メトキシプロピオン酸メチル、3-エトキシプロピオン酸メチルエチル、3-メトキシプロピオン酸エチル、3-エトキシプロピオン酸、3-メトキシプロピオン酸、3-メトキシプロピオン酸プロピル、3-メトキシプロピオン酸ブチル、乳酸メチルエステル、乳酸エチルエステル、乳酸n-プロピルエステル、乳酸n-ブチルエステル、乳酸イソアミルエステル又は前記式[D-1]~式[D-3]で示される溶媒などを挙げることができる。
これら貧溶媒は、液晶配向剤に含まれる溶媒全体の1~80質量%であることが好ましい。なかでも、10~80質量%が好ましい。より好ましいのは20~70質量%である。
本発明の液晶配向膜は、上記液晶配向剤を基板に塗布し、乾燥、焼成して得られる膜である。本発明の液晶配向剤を塗布する基板としては透明性の高い基板であれば特に限定されず、ガラス基板、窒化珪素基板、アクリル基板、ポリカーボネート基板等のプラスチック基板等を用いることができ、液晶駆動のためのITO電極等が形成された基板を用いることがプロセスの簡素化の点から好ましい。また、反射型の液晶表示素子では片側の基板のみにならばシリコンウエハー等の不透明な物でも使用でき、この場合の電極はアルミニウム等の光を反射する材料も使用できる。
ラビング処理は既存のラビング装置を利用して行うことができる。この際のラビング布の材質としては、コットン、ナイロン、レーヨンなどが挙げられる。ラビング処理の条件としては一般に、回転速度300~2000rpm、送り速度5~100mm/s、押し込み量0.1~1.0mmという条件が用いられる。その後、純水やアルコールなどを用いて超音波洗浄によりラビングにより生じた残渣が除去される。
偏光された紫外線の消光比が高いほど、より高い異方性が付与できるため、好ましい。具体的には、直線に偏光された紫外線の消光比は、10:1以上が好ましく、20:1以上がより好ましい。
接触処理に使用する溶媒としては、光照射によって生成した分解物を溶解する溶媒であれば、特に限定されるものではない。具体例としては、水、メタノール、エタノール、2-プロパノール、アセトン、メチルエチルケトン、1-メトキシ-2-プロパノール、1-メトキシ-2-プロパノールアセテート、ブチルセロソルブ、乳酸エチル、乳酸メチル、ジアセトンアルコール、3-メトキシプロピオン酸メチル、3-エトキシプロピオン酸エチル、酢酸プロピル、酢酸ブチル、及び酢酸シクロヘキシルなどが挙げられる。これらの溶媒は2種以上を併用してもよい。
汎用性や安全性の点から、水、2-プロパンール、1-メトキシ-2-プロパノール及び乳酸エチルからなる群から選ばれる少なくとも1種がより好ましい。水、2-プロパンール、及び水と2-プロパノールの混合溶媒が特に好ましい。
上記接触処理の後に、使用した溶液中の有機溶媒を除去する目的で、水、メタノール、エタノール、2-プロパノール、アセトン、メチルエチルケトンなどの低沸点溶媒によるすすぎ(リンス)や乾燥のいずれか、又は両方を行ってよい。
加熱の温度としては、150~300℃が好ましい。温度が高いほど、分子鎖の再配向が促進されるが、温度が高すぎると分子鎖の分解を伴う恐れがある。そのため、加熱温度としては、180~250℃がより好ましく、200~230℃が特に好ましい。
加熱する時間は、短すぎると分子鎖の再配向の効果が得られない可能性があり、長すぎると分子鎖が分解してしまう可能性があるため、10秒~30分が好ましく、1分~10分がより好ましい。
本発明の液晶表示素子は、前記液晶配向膜の製造方法によって得られた液晶配向膜を具備することを特徴とする。
本発明の液晶表示素子は、本発明の液晶配向剤から前記液晶配向膜の製造方法によって液晶配向膜付きの基板を得た後、公知の方法で液晶セルを作製し、それを使用して液晶表示素子としたものである。
まず、透明なガラス製の基板を準備し、一方の基板の上にコモン電極を、他方の基板の上にセグメント電極を設ける。これらの電極は、例えばITO電極とすることができ、所望の画像表示ができるようパターニングされる。次いで、各基板の上に、コモン電極とセグメント電極を被覆するようにして絶縁膜を設ける。絶縁膜は、例えば、ゾル-ゲル法によって形成されたSiO2-TiO2からなる膜とすることができる。
次に、各基板の上に、本発明の液晶配向膜を形成する。次に、一方の基板に他方の基板を互いの配向膜面が対向するようにして重ね合わせ、周辺をシール材で接着する。シール材には、基板間隙を制御するために、通常、スペーサーを混入しておく。また、シール材を設けない面内部分にも、基板間隙制御用のスペーサーを散布しておくことが好ましい。シール材の一部には、外部から液晶を充填可能な開口部を設けておく。
次に、シール材に設けた開口部を通じて、2枚の基板とシール材で包囲された空間内に液晶材料を注入する。その後、この開口部を接着剤で封止する。注入には、真空注入法を用いてもよいし、大気中で毛細管現象を利用した方法を用いてもよい。次に、偏光板の設置を行う。具体的には、2枚の基板の液晶層とは反対側の面に一対の偏光板を貼り付ける。以上の工程を経ることにより、本発明の液晶表示素子が得られる。
本発明のシール剤には接着性、耐湿性の向上を目的として無機充填剤を配合してもよい。使用しうる無機充填剤としては特に限定されない。具体的には、球状シリカ、溶融シリカ、結晶シリカ、酸化チタン、チタンブラック、シリコンカーバイド、窒化珪素、窒化ホウ素、炭酸カルシウム、炭酸マグネシウム、硫酸バリウム、硫酸カルシウム、マイカ、タルク、クレー、アルミナ、酸化マグネシウム、酸化ジルコニウム、水酸化アルミニウム、珪酸カルシウム、珪酸アルミニウム、珪酸リチウムアルミニウム、珪酸ジルコニウム、チタン酸バリウム、硝子繊維、炭素繊維、二硫化モリブデン、アスベスト等が挙げられる。 なかでも、球状シリカ、溶融シリカ、結晶シリカ、酸化チタン、チタンブラック、窒化珪素、窒化ホウ素、炭酸カルシウム、硫酸バリウム、硫酸カルシウム、マイカ、タルク、クレー、アルミナ、水酸化アルミニウム、珪酸カルシウム、又は珪酸アルミニウムが好ましい。無機充填剤は2種以上を混合して用いても良い。
NMP:N-メチル-2-ピロリドン、 BCS:ブチルセロソルブ
GBL:γ-ブチロラクトン、 THF:テトラヒドロフラン
装置:Varian NMR system 400NB(400MHz)(Varian社製)、及びJMTC-500/54/SS(500MHz)(JEOL社製)
測定溶媒:CDCl3(重水素化クロロホルム),DMSO-d6(重水素化ジメチルスルホキシド)
基準物質:TMS(テトラメチルシラン)(δ:0.0ppm,1H)及びCDCl3(δ:77.0ppm,13C)
1H-NMR(400MHz, DMSO-d6, δppm):8.20(s, 2H), 7.25(d, 4H, J = 6.8 Hz), 6.81(d, 4H, J = 6.8 Hz), 6.06(t, 2H, J = 5.8 Hz), 3.75(q, 12H, J = 7.5 Hz), 3.14(s, 3H), 3.06-3.01(m, 4H), 1.48-1.44(m, 4H), 1.15(t, 18H, J = 7.5 Hz), 0.57-0.53(m, 4H).
1H-NMR(400MHz, DMSO-d6, δppm):8.11(s, 2H), 7.83(s, 2H), 7.50(d, 2H, J = 8.8 Hz), 7.17(d, 4H, J = 7.0 Hz), 7.15(d, 2H, J = 8.8 Hz), 6.72(d, 4H, J = 7.0 Hz), 6.03-6.00(m, 2H), 3.84(s, 3H), 3.75(q, 12H, J = 7.0 Hz), 3.25(s, 6H), 3.05-2.99(m, 4H), 1.48-1.43(m, 4H), 1.14(t, 18H, J = 7.0 Hz), 0.57-0.52(m, 4H).
1H-NMR(400MHz, DMSO-d6, δppm):8.36(s, 2H), 7.41(d, 4H, J = 6.8 Hz), 7.36(d, 4H, J = 6.8 Hz), 7.02(d, 4H, J = 6.8 Hz), 6.81(d, 4H, J = 6.8 Hz), 6.13(t, 2H, J = 5.8 Hz), 3.76(q, 12H, J = 7.0 Hz), 3.22(s, 6H), 3.08-3.03(m, 4H), 1.50-1.46(m, 4H), 1.14(t, 18H, J = 7.0 Hz), 0.58-0.54(m, 4H).
1H-NMR(400MHz, DMSO-d6, δppm):8.16(s, 2H), 7.20(s, 4H), 6.04(t, 2H, J = 5.6 Hz), 3.69(q, 8H, J = 7.0 Hz), 3.05-2.99(m, 4H), 1.46-1.41(m, 4H), 1.13(t, 12H, J = 7.0 Hz), 0.55-0.50(m, 4H), 0.06(s, 6H).
下記合成例における重合体溶液の粘度は、E型粘度計TVE-22H(東機産業社製)を用い、サンプル量1.1mL、コーンロータTE-1(1°34’、R24)、温度25℃で測定した。
撹拌装置付き及び窒素導入管付きの200mLlの四つ口フラスコに、DA-1(4.03g,16.5mmol)、DA-2(3.59g、9.0mmol)、及びDA-3(2.51g、4.5mmol)を加えた後、NMP(74.0g)を加え、窒素を送りながら撹拌し溶解させた。この溶液を撹拌しながらCA-1を(4.37g、19.5mmol)及びNMPを9.0gを加え、40℃条件下にて3時間攪拌した。その後、25℃条件下にてCA-2を(1.71g,8.7mmol)、及びNMPを9.0g加えた後、さらに12時間攪拌することでポリアミック酸溶液(粘度は480mPa・s)を得た。このポリアミック酸の分子量はMn=10,660であり、Mw=20,512であった。
合成例1で得られたポリアミック酸溶液を、得られる液晶配向剤中の溶媒表1に示す組成になるように、攪拌しながら、溶媒及び添加剤S1、S2、又はS3を加え、更に室温で2時間撹拌することにより液晶配向剤を得た。
※2:液晶配向剤中の全重合体100重量部に対する各添加剤の含有量(重量部)を示す。
※3:液晶配向剤100質量部に対する各溶媒の含有量(重量部)を示す。
FFS方式の液晶表示素子の構成を備えた液晶セルを作製する。初めに、電極付きの基板を準備した。基板は、縦30mm、横35mm、厚さ0.7mmのガラス基板である。基板上には第1層目として対向電極を構成する、IZO電極が全面に形成されている。第1層目の対向電極の上には、第2層目として、CVD法により成膜されたSiN(窒化珪素)膜が形成されている。第2層目のSiN膜の膜厚は500nmであり、層間絶縁膜として機能する。第2層目のSiN膜の上には、第3層目として、IZO膜をパターニングして形成された櫛歯状の画素電極が配置され、第1画素及び第2画素の2つの画素を形成している。各画素のサイズは、縦10mm、横約5mmである。このとき、第1層目の対向電極と第3層目の画素電極とは、第2層目のSiN膜の作用により、電気的に絶縁されている。
各画素の第1領域と第2領域とを比較すると、それらを構成する画素電極の電極要素の形成方向が異なるものとなっている。すなわち、後述する液晶配向膜のラビング方向を基準とした場合、画素の第1領域では、画素電極の電極要素が+10°の角度(時計回り)をなすように形成され、画素の第2領域では、画素電極の電極要素が-10°の角度(時計回り)をなすように形成されている。すなわち、各画素の第1領域と第2領域とでは、画素電極と対向電極との間の電圧印加によって誘起される液晶の、基板面内での回転動作(インプレーン・スイッチング)の方向が、互いに逆方向となるように構成されている。
上記液晶セルを、偏光軸が直交するように配置された2枚の偏光板の間に設置し、画素電極と対向電極とを短絡して同電位にした状態で、2枚の偏光板の下からLEDバックライトを照射しておき、2枚の偏光板の上で測定するLEDバックライト透過光の輝度が最小となるように、液晶セルの角度を調節した。
次に、この液晶セルに周波数30Hzの矩形波を印加しながら、23℃の温度下でのV-T特性(電圧-透過率特性)を測定し、相対透過率が23%となる交流電圧を算出した。この交流電圧は電圧に対する輝度の変化が大きい領域に相当するため、蓄積電荷を輝度を介して評価するのに都合がよい。
次に、23℃の温度下において相対透過率が23%となる交流電圧で、なおかつ周波数30Hzの矩形波を5分間印加した後、+1.0Vの直流電圧を重畳し30分間駆動させた。その後、直流電圧を切り、再び相対透過率が23%となる交流電圧で、なおかつ周波数30Hzの矩形波のみを15分間印加した。
蓄積した電荷の緩和が速いほど、直流電圧を重畳したときの液晶セルへの電荷蓄積も速いことから、蓄積電荷の緩和特性は、直流電圧を重畳した直後の相対透過率から2%以上低下するまでに要した時間で評価した。すなわち、相対透過率が30分以内に2%以上低下した場合に「良好」、30分経過しても相対低下率が2%以上低下しない場合に「不良」と定義して評価を行った。
この液晶セルを用い、60℃の恒温環境下、周波数30Hzで9VPPの交流電圧を190時間印加した。その後、液晶セルの画素電極と対向電極との間を短絡させた状態にし、そのまま室温に一日放置した。
放置の後、液晶セルを偏光軸が直交するように配置された2枚の偏光板の間に設置し、電圧無印加の状態でバックライトを点灯させておき、透過光の輝度が最も小さくなるように液晶セルの配置角度を調整した。そして、第1画素の第2領域が最も暗くなる角度から第1領域が最も暗くなる角度まで液晶セルを回転させたときの回転角度を角度Δとして算出した。第2画素でも同様に、第2領域と第1領域とを比較し、同様の角度Δを算出した。そして、第1画素と第2画素の角度Δ値の平均値を液晶セルの角度Δとして算出した。この液晶セルの角度Δの値が0.2度未満の場合には「良好」、角度Δの値が0.2度以上の場合には「不良」と定義し評価した。
得られた液晶セルに60℃の温度下で1Vの電圧を60μs間印加し、50ms後の電圧を測定し、電圧がどのくらい保持できているかを電圧保持率として計算した。なお、電圧保持率の測定には、東陽テクニカ社製の電圧保持率測定装置VHR-1を使用した。
縦40mm、横40m、厚さ1.0mmの石英基板を準備した。次に、液晶配向剤を1.0μmのフィルターで濾過した後、上記石英基板にスピンコートした。次いで、80℃のホットプレート上で2分間乾燥後、230℃で20分間焼成し、各基板上に膜厚100nmのポリイミド膜を得た。
透明性の評価は、前記手法で得られた基板の透過率を測定することで行った。具体的には、測定装置にUV-3600(島津製作所社製)を用い、温度25℃、スキャン波長を300~800nmの条件で、透過率を測定した。その際、リファレンス(参照例)に何も塗布していない石英基板を用いて行った。評価は、400~800nmの波長の平均透過率を算出し、透過率が高いものほど、透明性に優れるとした。
上記実施例1~3、及び比較例1~2の各液晶配向剤を使用する液晶表示素子に関し、上記で実施した残像消去時間の評価、液晶配向の安定性評価、及び透明性の評価の結果を表2に示す。
なお、2018年3月19日に出願された日本特許出願2018-51091号の明細書、特許請求の範囲、及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。
Claims (12)
- 下記(A)成分、(B)成分、及び有機溶媒を含有することを特徴とする液晶配向剤。
(A)成分:下記式(2)で表される構造を有するポリイミド前駆体及び該ポリイミド前駆体のイミド化重合体からなる群から選ばれる少なくとも1種の重合体
(B)成分:下記式(1)で表される化合物
但し、式(1)中、Q1及びQ2はそれぞれ独立して、下記(Q1-1)、(Q1-2)及び単結合から選ばれる一種であるが、式(1)中、Q1及びQ2の少なくとも1つは(Q1-1)及び(Q1-2)から選ばれる一種である。R1は水素原子、又は一価の有機基である。
L1及びL2は水素原子である。但し、Q1が(Q1-1)である場合は、L1及びL2は一緒になって単結合を形成していてもよい。
S1及びS2は、それぞれ独立に、下記式(S)で表される基である。
但し、式(S)中、R2は水素原子、又はアルキル基である。Lは炭素数2~20のアルキレンである。R3及びR4は、それぞれ独立に炭素数1~4のアルキル基、炭素数2~4のアルケニル基、又は炭素数2~4のアルキニル基である。qは1~3の自然数を表す。*は式(1)への結合を表す。 - 前記ポリイミド前駆体が、その有する全構造単位に対して、前記式(3)で表される構造単位を20~100モル%含む請求項2に記載の液晶配向剤。
- 前記(B)成分が、下記(B-1)乃至(B-9)からなる群から選ばれる少なくとも一種の化合物である請求項1~3のいずれか1項に記載の液晶配向剤。
(B-1):前記式(1)において、q1、q2が0であり、Q1が(Q1-1)であり、L1、L2が水素原子である化合物、
(B-2):前記式(1)において、q1、q2が0であり、Q1が(Q1-1)であり、L1、L2が一緒になって単結合である化合物、
(B-3):前記式(1)において、q1、q2が1であり、Q1が(Q1-1)であり、Q2が(Q1-1)であり、L1、L2が水素原子である化合物、
(B-4):前記式(1)において、q1、q2が1であり、Q1が(Q1-1)であり、Q2が単結合であり、L1、L2が水素原子である化合物、
(B-5):前記式(1)において、q1、q2が1であり、Q1が(Q1-1)であり、Q2が(Q1-1)であり、L1、L2が一緒になって単結合である化合物、
(B-6):前記式(1)において、q1、q2が1であり、Q1が単結合であり、Q2が(Q1-1)であり、L1、L2が水素原子である化合物、
(B-7):前記式(1)において、q1、q2が1であり、Q1が(Q1-1)であり、Q2が単結合であり、L1、L2が一緒になって単結合である化合物、
(B-8):前記式(1)において、q1、q2が0であり、Q1が(Q1-2)であり、L1、L2が水素原子である化合物。
(B-9):前記式(1)において、q1、q2が1であり、Q1が(Q1-2)であり、L1、L2が水素原子である化合物。 - 前記有機溶媒が、N,N-ジメチルホルムアミド、N,N-ジメチルアセトアミド、N-メチル-2-ピロリドン、N-エチル-2-ピロリドン、ジメチルスルホキシド、γ-ブチロラクトン、1,3-ジメチル-イミダゾリジノン、メチルエチルケトン、シクロヘキサノン、シクロペンタノン、又は4-ヒドロキシ-4-メチル-2-ペンタノンである請求項1~5のいずれか1項に記載の液晶配向剤。
- 前記有機溶媒が、液晶配向剤を塗布した際の液晶配向膜の塗膜性や表面平滑性を向上させる溶媒を含む請求項6に記載の液晶配向剤。
- 前記(A)成分を含む重合体を、液晶配向剤中、1~10質量%含有する請求項1~7のいずれか1項に記載の液晶配向剤。
- 前記(B)成分を、前記(A)成分に対して、0.1~20質量%含有する請求項1~8のいずれか1項に記載の液晶配向剤。
- 請求項1~9のいずれか1項に記載の液晶配向剤から得られる液晶配向膜。
- 請求項10に記載の液晶配向膜を具備する液晶表示素子。
- 表示素子が横電界方式である請求項11に記載の液晶表示素子。
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