JP2000144133A - Nematic type liquid crystal composition, optical element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal polymer permitting the application of a liquid crystal polymer solution-coating method, thereby capable of being easily and efficiently be produced in a large area, capable of being cross-linked by a practical means, having an excellent monodomain-orienting property, and capable of forming a nematic oriented optical element excellent in heat resistance. SOLUTION: This nematic type liquid crystal composition capable of being cross-linked is prepared by adding a low molecular compound having one or more cross-linking groups to a side chain type nematic liquid crystal polymer having segments SR of the formula [R1, R2 are each H or methyl; Q is an organic group having a cross-linking group; 1<=(n)<=100] as repeating units. An optical element comprises the cross-linked product of the liquid crystal composition. The method for producing the optical element comprises orienting the liquid crystal composition and subsequently applying an electromagnetic wave irradiation and/or a heating treatment to the oriented composition to cross-link the cousposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nematic liquid crystal composition capable of forming an optical element having excellent heat resistance by performing a crosslinking treatment while maintaining nematic alignment, and a method for producing the optical element.

[0002]

BACKGROUND OF THE INVENTION Various optical elements obtained by aligning a nematic liquid crystal polymer have been proposed, and are expected to be applied to, for example, a liquid crystal display device as a retardation plate for compensating a retardation. However, such an optical element is formed by applying a solution of a liquid crystal polymer on an alignment film, drying and then heating and cooling above a glass transition temperature, and its heat resistance depends on the glass transition temperature. However, there was a problem with poor heat resistance.

That is, the above-mentioned optical element maintains its nematic orientation state below the isotropic phase transition temperature when no stress is applied, but the orientation collapses around the glass transition temperature when stress is applied. Optical characteristics change. The stress in the optical element is caused by a dimensional change or the like due to a temperature change or the like under a use condition in a practical mode, such as when the optical element is bonded to a liquid crystal cell or the like via an adhesive layer together with a polarizing plate or the like.
In a practical form, stress generation is rather normal. Incidentally, in the case of a dimensional change due to a temperature change of the polarizing plate, a contraction stress is generated in the optical element adhered to the polarizing element via the adhesive layer.

[0004] As a measure for improving the heat resistance of the optical element described above, in a method using a liquid crystal polymer having a high glass transition temperature, the temperature for forming the optical element increases with an increase in the alignment treatment temperature. Since the heat resistance temperature to be used is also high and the practical restrictions such as restrictions on the base material to be used are large, measures to improve the heat resistance by cross-linking the liquid crystal polymer are being studied.

Heretofore, as the above-mentioned crosslinked product, there has been known a crosslinked product of a liquid crystal polymer having a crosslinkable group such as an acryloyl group at a terminal of a side chain with a photopolymerization initiator through an ultraviolet ray or the like (Japanese Patent Laid-Open No. Hei 4 (1994)). -12322 publication). This is because even if a liquid crystal polymer having no cross-linking group is cross-linked with a low-molecular-weight cross-linking agent, the low-molecular-weight compound causes a reduction in heat resistance, and offsets the improvement in heat resistance due to the cross-linking process as a whole. Is poorly improved in heat resistance. Further, in a method in which a fluidized bed made of a low-molecular polymerizable liquid crystal compound is interposed between two substrates and polymerized by light irradiation or the like, the production efficiency is poor and a large-area body is hardly obtained.

However, in the above-mentioned known method, it is necessary to perform a crosslinking treatment by irradiating a large amount of light while increasing the fluidity of the liquid crystal polymer under high-temperature heating, and it is difficult to control the conditions of the crosslinking treatment, which makes the method practical. There were few difficulties.

A method has been proposed in which a polyfunctional crosslinking agent is blended with a liquid crystal polymer having a crosslinking group at the side chain end of a segment having no liquid crystal orientation to carry out crosslinking treatment by light irradiation (Japanese Patent Laid-Open No. Hei 9-260,019). No. 7,261,137), there is a problem that the obtained alignment layer is of a multi-domain type and is not suitable for forming an optical element that requires uniform optical characteristics by mono-domain alignment.

[0008]

The present invention can be applied to a liquid crystal polymer solution coating method, so that a large-area body can be easily and efficiently manufactured, and can be cross-linked by practical means to have excellent monodomain alignment. Another object of the present invention is to develop a liquid crystal polymer capable of forming a nematic alignment optical element having excellent heat resistance.

[0009]

The present invention provides a low molecular weight compound having one or more crosslinking groups in a side chain type nematic liquid crystal polymer having a segment SR represented by the following general formula (I) as a repeating unit. It is intended to provide a nematic liquid crystal composition which is compounded and capable of undergoing a crosslinking treatment. General formula (I): (However, R ¹ is hydrogen or a methyl group, Q is an organic group having a crosslinking group, and 1 ≦ n ≦ 100.)

Further, the present invention provides an optical element comprising a cross-linked product of the above nematic liquid crystal composition, and a method of aligning the above nematic liquid crystal composition, and then irradiating the nematic liquid crystal composition with one of electromagnetic wave irradiation and heating. Another object of the present invention is to provide a method for producing an optical element, wherein a cross-linking treatment is performed by both.

[0011]

According to the present invention, the above-mentioned liquid crystal composition can be made into a solution, applied and dried, heated to a glass transition temperature or higher, and then cooled. The heat resistance can be improved by cross-linking through a low-molecular compound containing a cross-linking group by means of practical conditions without disturbing. Therefore, it is possible to perform a low-temperature alignment treatment according to a conventional liquid crystal polymer, and easily and efficiently manufacture a large-area body of a nematic alignment optical element having excellent heat resistance and excellent monodomain alignment. Further, the low-molecular compound to be blended in the present invention also has a feature that almost no coloring is caused thereby.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A nematic liquid crystal composition according to the present invention is obtained by adding one or two crosslinking groups to a side chain type nematic liquid crystal polymer having a segment SR represented by the following general formula (I) as a repeating unit. A cross-linking treatment is possible by blending the low molecular compound having the above. General formula (I): (However, R ¹ is hydrogen or a methyl group, Q is an organic group having a crosslinking group, and 1 ≦ n ≦ 100.)

The segment SR represented by the general formula (I) participates in the crosslinking of the liquid crystal polymer through the organic group Q having a crosslinking group. Therefore the segment S
R may be an appropriate one having one or two or more crosslinking groups capable of participating in crosslinking.

The more preferable organic group Q is a compound having a crosslinkable C ＝ C bond such as an acryloyl group, a methacryloyl group, a cinnamoyl group or a vinyl ether group, which is more preferable in terms of crosslinkability under practical conditions.

Incidentally, examples of the preferred organic group Q include those represented by the following general formula (II). Therefore, as the segment SR, the general formula (VI
And those represented by I). (However, R ¹ and R ² are hydrogen or methyl groups, and A, B, D
Is an organic group. )

In the general formula (II), A is a compound represented by the general formula (III): Z ¹ (CH ₂ ) mR ³ Z ² , and B is a para-substituted cyclic structure type compound. And D is one represented by the general formula (V): Z ³ (CH ₂ ) × Z ⁴ .

Formula (III): Z ¹ (CH ₂ ) mR ³ Z ²
In the above, Z ¹ and Z ² represent -COO-, -O-, -OCO
— Or — (CH ₂ ) g — (g is an integer of 0 to 6);
m is an integer of 0 to 12, and R ³ is represented by the following general formula (IV). Note that Z ¹ and Z ² may be the same or different. (However, h is 0 when m = 0 in the general formula (III) and 1
When ≦ m ≦ 12, it is 1 and f is 1 or 2. )

On the other hand, examples of the para-substituted cyclic structure type compound of B in the above general formula (II) include the following.

In particular, the following para-substituted cyclic structure type compounds are preferred as B.

On the other hand, in the general formula (V) for forming D in the general formula (II): Z ³ (CH ₂ ) x Z ⁴ , Z ³ is x = 0
When-(CH ₂ ) j-(j is an integer of 0 to 6), 1 ≦ x ≦
In the case of 10, -COO-, -O-, -OCO-, or-
(CH ₂₎ k-a (k is an integer of 0~6), Z ⁴ is -C
OO -, - O -, - OCO-, or - (CH ₂₎ p- (p
Is an integer of 0 to 6). Note that Z ³ and Z ⁴ may be the same or different.

As the side chain type nematic liquid crystal polymer,
While having the above-mentioned segment SR, it is possible to use an appropriate material which has a thermotropic property, forms a nematic alignment state through an alignment film or the like in a liquid crystalization temperature range, and forms a monodomain, and particularly regarding the type thereof. There is no limitation. Incidentally, examples thereof include those having, as a repeating unit, a segment SN having a conjugated linear atomic group (mesogen) imparting nematic orientation together with the segment SR.

That is, a nematic orientation unit having a mesogen composed of, for example, a para-substituted cyclic compound, if necessary, via a spacer portion, together with the segment SR, is incorporated into a main chain skeleton composed of a vinyl-based chain such as polyacrylate or polymethacrylate. And those having a segment SN introduced as a side chain.

The above-mentioned para-substituted cyclic compound includes
Examples thereof include those having a para-substituted aromatic unit or a para-substituted cyclohexyl ring unit such as an azomethine type, an azo type, an azoxy type, an ester type, a tolan type, a phenyl type, a biphenyl type, a phenylcyclohexyl type, and a bicyclohexyl type. . The terminal substituent at the para position in the para-substituted cyclic compound may be an appropriate one such as, for example, a cyano group, an alkyl group, an alkoxy group or a halogen group.

The spacer portion may be an appropriate one exhibiting flexibility, for example, a polymethylene chain-(C
H ₂₎ v-or polyoxymethylene chain _{- (CH 2 CH 2 O)} w
-And the like. The number of repetitions of the structural unit forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion and the like.
0, especially 2 to 12, w for a polyoxymethylene chain
Is 0 to 10, especially 1 to 3.

The side chain type nematic liquid crystal polymer having the segments SR and SN is prepared by adding a monomer for forming a vinyl-based main chain such as (meth) acrylic acid ester to a Q group according to the general formula (I). A copolymerization method for polymerizing one or two or more of a monomer for forming a segment SR into which a component is introduced or a monomer for forming a segment SN in which a mesogen group is introduced via a spacer group as necessary, a hydroxyl group, a carboxyl group, A prepolymer for forming a main chain having a functional group such as halogen is synthesized in advance, and the segment SR or the segment S is synthesized via the functional group.
It can be performed by an appropriate method such as a method of introducing a compound for forming N by a polymer reaction.

In the above-mentioned prepolymer method, for example, when the crosslinking group to be left in the monomer for forming the segment SR is involved in the polymerization of the main chain and cannot be effectively left in the monomer copolymerization method, It is particularly effective as a method for preparing a desired side chain type nematic liquid crystal polymer by using a prepolymer having a group at a terminal and introducing a crosslinking group via the functional group. In the prepolymer method, a monomer such as a monomer for forming the segment SN, which is not likely to deteriorate, may be previously copolymerized in the prepolymer.

In the above-mentioned copolymerization method and prepolymer method, for example, a side chain type nematic liquid crystal may be formed by an appropriate method according to a polymerization method of a vinyl monomer such as a radical polymerization method, a cation polymerization method or an anion polymerization method. A polymer or a prepolymer for forming a main chain can be prepared. When the radical polymerization method is applied, various polymerization initiators can be used, but those which decompose at an intermediate temperature having a high or low decomposition temperature such as azobisisobutyronitrile or benzoyl peroxide are preferred. .

Specific examples of the prepolymer system are shown below. That is, like the reaction steps shown below,
First, in step 1, DHP (3,4-dihydro-2H-pyran) is added to 4,4′-biphenol in THF (tetrahydrofuran) in the presence of TsOH (tosylic acid: catalyst), and the mixture is stirred at room temperature to mix one side. After THP protected biphenol, it was esterified with DCC (dicyclohexylcarbodiimide) with 4- (2-propenoyloxyethoxy) benzoic acid in methylene chloride in the presence of DMAP (dimethylaminopyridine: catalyst), Then T
Cleavage of the THP ether with hydrochloric acid in HF yields the monomer SR1 having a terminal hydroxyl group.

Next, in step 2, the segment S obtained above
A monomer obtained by copolymerizing a monomer SR1 for forming R and a monomer SN1 separately prepared for forming a segment SN to obtain a prepolymer, and then reacting it with acryloyl chloride to introduce an acryloyl group at a terminal. It is.

[0030]

The preparation of 4- (2-propenoyloxyethoxy) benzoic acid is carried out, for example, by heating ethylene chlorohydrin and 4-hydroxybenzoic acid to reflux in an aqueous alkali solution in the presence of potassium iodide (catalyst). After obtaining the hydroxycarboxylic acid by this, it can be carried out by a method of dehydrating it with acrylic acid or the like.

The monomer SN1 having a cyano group at the terminal can be obtained, for example, by converting 4- (2-propenoyloxyethoxy) benzoic acid and 4-cyano-4′-hydroxybiphenyl to DCC in the presence of DMAP (catalyst). And esterification.

Therefore, the side chain type nematic liquid crystal polymer used in the present invention can be prepared, for example, by a method according to the above.
Various types can be obtained by using a kind or two or more kinds of appropriate monomers for forming a segment. The content ratio of the segment SR and the segment SN in the side chain type nematic liquid crystal polymer can be appropriately determined depending on the crosslinking property and the heat resistance improving property therefrom, nematic orientation, etc.
In general, the segment SR is at least 3 mol%, preferably 5 to 70%.
Molar%, especially 10 to 50% by mole.

The molecular weight of the side chain type nematic liquid crystal polymer can be determined as appropriate. However, in general, the film forming properties, the film strength, the orientation and the uniformity thereof, especially the achievable monodomain orientation by the rubbing orientation film, etc. More preferably, those having a weight-average molecular weight of from 2,000 to 100,000, preferably from 22,000 to 80,000, and particularly preferably from 2,000 to 50,000.

As the low molecular weight compound to be compounded for the purpose of crosslinking the liquid crystal polymer, an appropriate compound having one or more crosslinking groups can be used, and a compound which does not disturb the alignment of the liquid crystal polymer can be preferably used. . Low molecular compounds are
It may or may not be liquid crystal itself,
A liquid crystalline polymer is preferable from the viewpoint of not disturbing the alignment of the liquid crystal polymer.

The structure and molecular weight of the low molecular weight compound are not particularly limited. However, from the viewpoint of crosslinkability under practical conditions, for example, the low molecular weight compounds such as acryloyl group, methacryloyl group, cinnamoyl group and vinyl ether group can be used. Those having a C ＝ C bond are preferred. Among them, those having an acryloyl group and / or a methacryloyl group are preferable, and those having a cross-linking group at the terminal as in the following general formula (VI) are particularly preferable.

[0037] (However, R ⁴ is hydrogen or a methyl group, and 0 ≦ t ≦ 20.) The core portion supporting the crosslinked portion may be an appropriate organic group, but is preferably a liquid crystal such as an aromatic ring. Is difficult to disturb.

The amount of the low molecular compound to be used in the liquid crystal polymer is such that the side chain type nematic liquid crystal is used because the heat resistance is insufficiently improved due to an insufficient amount (crosslinking is insufficient), and the precipitation during the alignment treatment due to the excessive amount and the alignment hindrance are prevented. 100 parts by weight or less per 100 parts by weight of polymer, preferably 1 to 70 parts by weight,
Particularly, 5 to 40 parts by weight is preferable.

The nematic liquid crystal composition can be prepared, for example, by mixing a side chain type nematic liquid crystal polymer and a low molecular compound via a solvent if necessary. As the solvent, an appropriate solvent that can dissolve the side chain type nematic liquid crystal polymer and the low molecular compound can be used, and there is no particular limitation. For example, 1,1,2,2
A single solvent or a mixed solvent such as tetrachloroethane, cyclohexanone, methylene chloride, chloroform, and tetrahydrofuran;

The optical element according to the present invention comprises a crosslinked product of a nematic liquid crystal composition. The production can be performed by an appropriate method according to a conventional orientation treatment. Incidentally, as an example, a method in which a solution of a nematic liquid crystal composition is spread on an alignment treatment surface, dried, and then heat-treated to form a nematic alignment layer, and then subjected to a crosslinking treatment, can be used. When forming the optical element, 1
One or more kinds of side chain type nematic liquid crystal polymers and low molecular weight compounds can be used.

As the alignment treatment surface, for example, a known one can be used for the alignment treatment of a low-molecular liquid crystal compound. Examples thereof include those in which a thin film of polyimide or polyvinyl alcohol is formed on a base material and the surface thereof is rubbed with a rayon cloth or the like, or one in which silicon oxide or the like is obliquely deposited, or a stretched film. Can be Note that an appropriate substrate that can withstand the heating temperature during the alignment treatment can be used as the substrate.

The liquid crystal composition solution is developed by, for example, developing a thin layer of the solution by an appropriate method such as a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method or a casting film forming method. It can be carried out by a method of drying and removing the solvent.

The heat treatment for orienting the spread layer of the liquid crystal composition can be performed by heating the liquid crystal polymer to a temperature range from a glass transition point to a molten state exhibiting an isotropic phase. The cooling conditions for fixing the alignment state are not particularly limited, and usually, the above-described heat treatment is performed for 3 hours.
Since it can be performed at a temperature of 00 ° C. or less, a natural cooling system is generally employed.

The spreading layer after the orientation treatment is crosslinked to form an oriented crosslinked product. The crosslinking treatment can be performed by one or both of electromagnetic wave irradiation and heating. Appropriate radiation such as ultraviolet rays and electron beams can be used for electromagnetic wave irradiation. The wavelength and irradiation amount of the electromagnetic wave can be determined as appropriate, but in the case of ultraviolet light, ultraviolet light having a wavelength longer than 300 nm, which is less absorbed by the liquid crystal polymer, is preferable. In the case of an electron beam, there is a difference depending on the system from the viewpoint of preventing the liquid crystal polymer from collapsing, but generally 1 to 200 Mrad is preferable.

In the above-mentioned crosslinking treatment, an appropriate amount of an initiator can be used, if necessary. As the initiator, an appropriate one according to the crosslinking method can be used, but an initiator which does not color the obtained optical element as much as possible can be preferably used. Incidentally, in the heat crosslinking method, it is necessary to use a high-temperature type initiator which does not decompose at the heating temperature during the alignment treatment.

On the other hand, in the crosslinking method using ultraviolet light, it is preferable to use a high-temperature type initiator which does not decompose at the heating temperature during the alignment treatment in both cases of irradiation with ultraviolet light and heat treatment. In addition, the absorption by the liquid crystal polymer is small.
Those which are decomposed by ultraviolet light having a wavelength longer than 00 nm are preferred.
Incidentally, examples thereof include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and oligo [2-hydroxy-2-methyl-1-
[4- (1-methylvinyl) phenyl] propanone] and the like.

The cross-linking treatment by electromagnetic wave irradiation is preferably performed under reduced pressure or oxygen-free condition in order to avoid the influence of oxygen inhibition. In the case of a crosslinking treatment by a heat treatment, the crosslinking treatment can be performed at an appropriate temperature between the glass transition temperature and the isotropic phase transition temperature of the liquid crystal polymer.

The optical element according to the present invention may have an appropriate form such as a form having a nematic-aligned liquid crystal layer on an appropriate base material, or a film form comprising a single layer of the oriented liquid crystal layer. A film composed of a single layer of liquid crystal can be obtained as a peeled product from the alignment-treated surface, and for the peeling and recovery, a rubbing film forming material having a releasable side chain composed of a long-chain alkyl group or the like is used. An appropriate method such as a method or a method of forming an alignment-treated surface on a glass plate having a surface modified with a silane compound having an alkyl chain having 8 to 18 carbon atoms can be applied as necessary.

On the other hand, in the case of an optical element comprising a superimposed material with a substrate, the substrate may be a stretched film such as a plastic film, a glass plate, a polymer sheet or a retardation plate, or an optical material such as a polarizing plate. An appropriate one can be used. As the plastic film, for example, a film made of an appropriate optically transparent plastic that may form a stretched film such as polymethyl methacrylate, polycarbonate, polyvinyl alcohol, polyarylate, polypropylene, other polyolefin, or polystyrene may be used. . In addition, as the base material, a material such as a glass plate or a triacetylcellulose film, which has as small a retardation as possible due to birefringence, can be particularly preferably used.

The thickness of the liquid crystal layer subjected to the alignment and crosslinking treatment can be appropriately determined depending on the optical characteristics and the like according to the purpose of use, but is generally 100 μm or less from the viewpoint of flexibility and the like.
0 μm or less, particularly 1 to 30 μm.

[0051]

EXAMPLES Reference Example 1 300 g of potassium hydroxide was added to 700 ml of ethanol / 30 of water.
0 ml of a mixed solution, 276 g of 4-hydroxybenzoic acid and a catalytic amount of potassium iodide were dissolved therein, 177 g of ethylene chlorohydrin was gradually added while heating, and the mixture was refluxed for about 15 hours. Ethanol was distilled off from the solution, and 2 L of water was added. The aqueous solution was washed twice with diethyl ether, and the precipitate was filtered off and dried as an acidic solution by addition of hydrochloric acid, and recrystallized from ethanol. 298 g of hydroxyethoxy) benzoic acid are obtained, 18.2 g of which
Was dissolved in 300 ml of THF (tetrahydrofuran), and 19.5 g of vinyl acrylate and lipase PS18 were added thereto.
g and a small amount of p-methoxyphenol.
Stirred for hours. The lipase PS was separated by filtration from the obtained reaction solution, and the filtrate was distilled off under reduced pressure.
The crystals were recrystallized from a mixture of hexane: 2/1 to obtain 17.5 g of 4- (2-propenoyloxyethoxy) benzoic acid.

9.44 g of the aforementioned 4- (2-propenoyloxyethoxy) benzoic acid and 2.2 of hydroxyquinone
g, a catalytic amount of DMAP (dimethylaminopyridine) and a small amount of BHT (butylhydroxytoluene) are dissolved in 100 ml of methylene chloride, and while stirring at room temperature, 9.89 g of DCC dissolved in 10 ml of methylene chloride is gradually added thereto. After reacting for 5 hours, the precipitated DCC urea was separated by filtration, and the filtrate was successively washed twice with 150 ml each of 0.5 N HCl, a saturated aqueous solution of sodium hydrogen carbonate and saturated saline, and dried over magnesium sulfate. After filtration, the solvent was distilled off and the residue was subjected to silica gel column chromatography (methylene chloride / diethyl ether: 25/1) to obtain 4.8 g of a diacryl compound having a purity of 97% or more.

REFERENCE EXAMPLE 2 Except that 4- (2-vinyloxyethoxy) benzoic acid was used in place of 4- (2-propenoyloxyethoxy) benzoic acid, the purity was 97% or more according to Reference Example 1. 4.67 g of a divinyl ether compound was obtained.

Reference Example 3 50 g of ethylene chlorohydrin and 5 g of tosylic acid monohydrate
Was dissolved in 700 ml of THF and THF was stirred at room temperature.
54.8 g (652 mmol) of DHP diluted with 50 ml was added dropwise over 30 minutes, and stirring was continued overnight. Then, about 3/4 of THF was distilled off from the reaction solution, and methylene chloride 8
Then, the mixture was washed twice with 800 ml of a saturated aqueous solution of sodium hydrogencarbonate and twice with a saturated saline solution, dried over magnesium sulfate, evaporated, and purified by silica gel column chromatography (methylene chloride). 85.7 ml of THP protected ethylene chlorohydrin were obtained.

Next, 56.4 g (512 mmol) of hydroquinone and a catalytic amount of potassium iodide were added to a solution of ethanol / water: 300 ml / 50 ml in which 80 g of potassium hydroxide was dissolved, and the mixture was refluxed with THP. Protected ethylene chlorohydrin was added dropwise over 1 hour and stirring was continued overnight. After that, the precipitated potassium chloride was filtered off, ethanol was distilled off from the filtrate, 800 ml of water was added to the concentrate, and the concentrate was washed with diethyl ether. The solution was adjusted to pH 4 with acetic acid while cooling in an ice bath, extracted with 500 ml of ether, and the organic layer was washed successively with 500 ml of a saturated aqueous solution of sodium hydrogencarbonate and brine, dried over magnesium sulfate, and dried. The solvent was distilled off, and 150 ml of methylene chloride was added thereto to precipitate unreacted hydroquinone, which was separated by filtration. The residue was redissolved in 600 ml of methylene chloride, washed twice with 500 ml of water to remove hydroquinone, the organic layer was dried over magnesium sulfate, the solvent was distilled off, and silica gel column chromatography (methylene chloride / diethyl ether: 6 / Purification in 1) gave 14.3 g of one-side substituted phenol.

Next, the above mono-substituted phenol 14.2
g, 4- (2-propenoyloxyethoxy) benzoic acid of Reference Example 1 (14.8 g), DMAP (0.36 g) and a small amount of BHT were added to methylene chloride (280 ml), and dissolved in methylene chloride (20 ml) with stirring at room temperature. DCC13.5
g was gradually added and stirring was continued overnight. Then, DCC urea was filtered off, and the filtrate was diluted with 700 ml of methylene chloride.
The resultant was washed twice with 600 ml of 0.5N-HCl, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride twice, dried over magnesium sulfate, and the solvent was distilled off to obtain 32.8 g of a THP terminal monomer. THF30 with a small amount of BHT
While refluxing in 0 ml, 3 g of tosylic acid monohydrate was added, and 15 ml of 12N-HCl was further added to reflux. THF was distilled off about 4/5 from the reaction solution, and methylene chloride
0 ml was added thereto, washed successively twice with 600 ml of a saturated aqueous solution of sodium hydrogencarbonate and twice with a saturated saline solution, dried over magnesium sulfate, and the solvent was distilled off. ) To obtain 7.78 g of a terminal hydroxy monomer.

4 g of the terminal cyanobiphenyl monomer and 2.4 g of the above-mentioned terminal hydroxy monomer were placed in a stream of nitrogen to obtain TH.
F was dissolved in 150 ml of reflux, and 0.264 g of azobisisobutyronitrile dissolved in 5 ml of THF was added thereto. The mixture was refluxed for 4 hours.
The polymer was precipitated by adding the polymerization solution to the resulting mixture, and the polymer was separated by filtration, washed with a mixed solution of methanol / THF: 3/2, and dried by filtration to obtain 3.59 g of a prepolymer. This prepolymer has a glass transition temperature of 85 ° C. and an isotropic phase transition temperature of 22.
5 ° C.

1.5 g of the above prepolymer, 421 μl of TEA (triethylamine), a catalytic amount of DMAP and a small amount of BHT are dissolved in 30 ml of dry THF by stirring at room temperature, and 245 μl of acryloyl chloride is added dropwise while cooling in a water bath. After completion of the dropwise addition, the water bath was removed and the mixture was stirred overnight while returning to room temperature. The resulting reaction solution was added to 500 ml of diethyl ether to precipitate a polymer by filtration, and the residue was washed with 300 ml of water and washed with TEA. Remove the hydrochloride,
The polymer alone was separated by filtration, dissolved in THF, dried over magnesium sulfate, dropped again into 500 ml of diethyl ether to precipitate the polymer, and dried by filtration to obtain 1 g of a liquid crystal polymer having an acryloyl group at the terminal. This polymer has a glass transition temperature of 77 ° C. and an isotropic phase transition temperature of 1
90 ° C.

The reaction steps of Reference Example 3 are shown below.

Reference Example 4

As in the above reaction step, 4- (2-propenoyloxyethoxy) benzoic acid 2 obtained in Reference Example 1
8.3 g of THF was stirred and refluxed in 560 ml of THF under a nitrogen stream, to which 1.97 g of azobisisobutyronitrile dissolved in 20 ml of THF was added and reacted for 4 hours, and poured into 1.8 L of diethyl ether to precipitate the polymer. The mixture was filtered off and dried to obtain 20.9 g of a terminal carboxylic acid polymer.

Next, the above-mentioned terminal carboxylic acid polymer 9.6 was prepared.
3 g and 5 drops of dimethylformamide in dry chloroform 1
Then, 8.95 ml of thionyl chloride was added dropwise, and the mixture was stirred while heating in a water bath at about 40 ° C. until the solution became transparent. Then, unreacted thionyl chloride and the solvent were distilled off, and the mixture was dried with THF. Wash and evaporate the solvent again and dry it with TH
F145 was dissolved in 145 ml.

Next, a solution prepared by dissolving 7 g of 4-cyano-4'-hydroxybiphenyl, 1.96 g of 4-acryloyl-hydroxybiphenyl, 4.45 ml of TEA, a catalytic amount of DMAP and a small amount of BHT in 90 ml of dry THF was added to the above solution. , And stirring was continued overnight, and the precipitated TEA was
The hydrochloride was filtered off, 750 ml of chloroform was added to the filtrate, and the mixture was washed with 1 L of a saturated aqueous solution of sodium hydrogen carbonate, dried over magnesium sulfate, and the solvent was distilled off.
The polymer was dissolved in 300 ml and dropped into 4 L of methanol to precipitate a polymer, which was separated by filtration and dried, and methanol / THF: 3 /
The mixture was washed with a mixed solvent of two, filtered and dried to obtain 12.3 g of a liquid crystal polymer having an acryloyl group at a terminal. This polymer had a glass transition temperature of 95 ° C.

Reference Example 5 In place of 4-acryloyl-hydroxybiphenyl, 4
Except for using-(2-vinyloxyethoxy) phenol, 12.0 g of a liquid crystal polymer having a vinyl ether group at a terminal and having a glass transition temperature of 75 ° C was obtained according to Reference Example 4.

Example 1 The liquid crystal polymer having an acryloyl group at the terminal obtained in Reference Example 3 was dissolved in 1,1,2,2-tetrachloroethane to obtain a 20% by weight solution, which was obtained in Reference Example 1. 15% by weight of the diacrytium compound was added to the liquid crystal polymer, and 5% by weight of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (hereinafter, initiator) was added. Spin-coated on the alignment-treated surface of the glass plate, dried, heated at 140 ° C. for 5 minutes, subjected to alignment treatment, allowed to cool at room temperature, and then heated to 120 ° C. while heating to an ultrahigh pressure mercury lamp (UIVO, UIV -1120)
And a color glass filter (UV-3, manufactured by Toshiba Glass Co., Ltd.)
Irradiation with ultraviolet rays at 650 mJ / cm ² was performed while cutting light having a wavelength of 300 nm or less through 3) to obtain a crosslinked nematic oriented optical element. The above-mentioned orientation-treated surface is formed by rubbing a polyvinyl alcohol layer having a thickness of about 0.1 μm with a rayon cloth (the same applies hereinafter).

Example 2 A cross-linked optical element having a nematic orientation was obtained in the same manner as in Example 1 except that the blending amount of the diacryl body was 20% by weight and the irradiation amount of ultraviolet rays was 200 mJ / cm ² .

Example 3 A cross-linked optical element having a nematic orientation was obtained in the same manner as in Example 1 except that the blending amount of the diacryl body was 20% by weight and the irradiation amount of ultraviolet rays was 330 mJ / cm ² .

Example 4 The liquid crystal polymer having an acryloyl group at the terminal obtained in Reference Example 4 was dissolved in 1,1,2,2-tetrachloroethane to form a 20% by weight solution, which was obtained in Reference Example 1. 20% by weight of a diacrylic substance was added to the liquid crystal polymer, and 2% by weight of an initiator was further added. The solution was spin-coated on an alignment-treated surface of a glass plate, dried, and heated at 140 ° C. for 5 minutes to perform alignment. After cooling at room temperature, the mixture was irradiated with 600 mJ / cm ^{2 of} ultraviolet light while being heated to 160 ° C. while being irradiated with an ultra-high pressure mercury lamp and cutting light having a wavelength of 300 nm or less through a color glass filter. An optical element having a nematic orientation was obtained.

Example 5 The liquid crystal polymer having an acryloyl group at the terminal obtained in Reference Example 4 was dissolved in 1,1,2,2-tetrachloroethane to form a 20% by weight solution. A crosslinked nematic-aligned optical element was obtained in the same manner as in Example 4 except that the liquid was added to the liquid crystal polymer in an amount of 20% by weight, and the initiator was added in an amount of 5% by weight.

Example 6 A crosslinked nematic-aligned optical element was prepared in the same manner as in Example 4, except that the amount of the initiator relative to the liquid crystal polymer was set to 5% by weight and the ultraviolet ray was irradiated while heating at 180 ° C. Obtained.

Example 7 A cross-linked optical element having a nematic orientation was obtained in the same manner as in Example 5, except that the crosslinking treatment was carried out by irradiating an electron beam at 40 Mrad at room temperature.

Example 8 The liquid crystal polymer having a vinyl ether group at the terminal obtained in Reference Example 5 was dissolved in tetrachloroethane to form a 20% by weight solution, and the divinyl ether compound obtained in Reference Example 2 was added to the liquid crystal polymer. After adding 20% by weight and further adding 5% by weight of an initiator, the solution is spin-coated on an alignment-treated surface of a glass plate, dried, heated at 140 ° C. for 5 minutes, and subjected to an alignment treatment, and allowed to cool at room temperature. UV light at a wavelength of 300 nm or less was cut by a super-high pressure mercury lamp while heating to 140 ° C. and passing through a colored glass filter.
Irradiation with mJ / cm ² gave a crosslinked nematic oriented optical element.

Comparative Example 1 An optical element having a nematic orientation was obtained in the same manner as in Example 1 except that the following liquid crystal polymer was used.

Comparative Example 2 An optical element having a nematic orientation was obtained in the same manner as in Example 5, except that the diacrylic compound and the initiator were not blended and the crosslinking treatment with ultraviolet rays was not performed.

Comparative Example 3 An optical element having a nematic orientation was obtained in the same manner as in Example 5 except that the diacryl compound was not used.

Comparative Example 4 An optical element having a nematic orientation was obtained in the same manner as in Example 5 except that no crosslinking treatment was performed with ultraviolet rays.

Evaluation Test The optical elements obtained in Examples and Comparative Examples were bonded to a polarizing plate (G1220DU, manufactured by Nitto Denko Corporation) via an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm and heated at various temperatures for 1 hour. The change in appearance was visually observed, and the maximum temperature at which no change was observed was evaluated as the heat-resistant temperature. The results are shown in the following table.

[0078]

From the table, it can be seen that in the optical elements of the examples, the heat resistance was improved by 25 ° C. or more by the crosslinking treatment.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Yoshioka 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Shu Mochizuki 1-1-1-2 Shimohozumi, Ibaraki-shi, Osaka F-term in Nitto Denko Corporation (reference) 4H027 BA01 BA13 BD01 BD12 BD24

Claims (8)

[Claims] 1. Formula (I): (However, R ¹ is hydrogen or a methyl group, Q is an organic group having a crosslinking group, and 1 ≦ n ≦ 100.) In a side chain type nematic liquid crystal polymer having a segment SR represented by a repeating unit, A nematic liquid crystal composition comprising a low molecular compound having one or more crosslinking groups, and capable of crosslinking. 2. The segment S according to claim 1, wherein the side chain type nematic liquid crystal polymer imparts nematic orientation.
Q in the general formula (I) for forming the segment SR while having N as a repeating unit is represented by the following general formula (II)
A nematic liquid crystal composition represented by the formula: (However, R ² is hydrogen or a methyl group, and A, B, and D are organic groups.) 3. The method according to claim 2, wherein A in the general formula (II) is represented by the general formula (III): Z ¹ (CH ₂ ) mR ³ Z ² (wherein
Z ¹ and Z ² are the same or different from each other, -COO-, -O-, -OC
O-, or - (CH ₂₎ g- a (g is an integer of Less than six), m is an integer of 0 to 12, R ³ is represented by the following general formula (IV)
It is represented by ) (However, h is 0 when m = 0 in the general formula (III) and 1
When ≦ m ≦ 12, it is 1 and f is 1 or 2. )
Wherein B is a para-substituted cyclic structure type compound, and D is a general formula (V): Z ³ (CH ₂ ) x Z ⁴ (where,
Z ³ when the _{x = 0 - (CH 2)} j- (j is 0-6 integer), when 1 ≦ x ≦ 10 -COO -, - O -, - OC
O-, or - with (CH ₂₎ k- (k is an integer of 0 to 6), Z
⁴ Z ³ are the same as or different of -COO -, - O -, - OCO
-, or - (CH ₂₎ p- (p is an integer of 0 to 6) is represented by. A) a nematic liquid crystal composition. 4. The nematic liquid crystal composition according to claim 1, wherein the crosslinking group of the low-molecular compound has a C 含 む C bond. 5. The nematic liquid crystal composition according to claim 4, wherein the low molecular weight compound has a crosslinking group represented by the following general formula (VI). (However, R ⁴ is hydrogen or a methyl group, and 0 ≦ t ≦ 20.) 6. The low molecular weight compound according to claim 1, wherein the low molecular weight compound is contained in 100 parts by weight of the side chain type nematic liquid crystal polymer.
A nematic liquid crystal composition, which is blended in an amount of up to 70 parts by weight. 7. An optical element comprising a crosslinked product of the nematic liquid crystal composition according to claim 1. 8. A method for producing an optical element, comprising aligning the nematic liquid crystal composition according to claim 1 and subjecting the liquid crystal composition to crosslinking treatment by one or both of irradiation with electromagnetic waves and heating.