JPH07101904A - Biphenyl methacrylate derivative and polymer dispersion type liquid crystal display element using the same - Google Patents

Abstract

PURPOSE:To obtain a new biphenyl methacrylate derivative suitable as one material for constituting a liquid crystal composition useful as an electrooptical display element for a polymer dispersion type liquid crystal display device. CONSTITUTION:A biphenyl methacrylate derivative of formula I (X is fluorine or H) such as 3-fluoro-biphenyl-4, 4-diyl dimethacrylate. The compound of formula I is obtained by reacting a compound of formula II with methyl iodide in a solution of potassium hydroxide in ethanol to give a compound of formula III, then treating the compound of formula III with magnesium to prepare a Grignard reagent, reacting the reagent with triisopropyl borate in tetrahydrofuran to give a compound of formula IV, then coupling the compound of formula IV with a compound of formula V to give a compound of formula VI, then reducing this compound to give a compound of formula VII and esterifying this compound with methacryloyl chloride of formula VIII.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel organic compound, and further to form a liquid crystal composition used as an electro-optical display element, a biphenyl methacrylate derivative which is one of the materials and a polymer using the same. The present invention relates to a dispersion type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, as a bright display element which does not use a polarizing plate, a display element in which a liquid crystal and a polymer are dispersed is drawing attention. The principle of operation of this display element utilizes the difference in the refractive index between the liquid crystal and the polymer.When the refractive index of the liquid crystal and that of the polymer match when an electric field is applied, a transmissive state is shown, and when the electric field is removed, the refractive index differs. In that case, the scattering state is indicated (Tokukaisho Sho 58-501631, which is called NCAP).
In addition, a display element of the opposite mode has been developed, which transmits when no electric field is applied and scatters when an electric field is applied (Mol.Cryst.Liq.Crys
t., 198, 357 (1991), which is called the reverse type). For these modes, a method of improving visibility by mixing a dye has also been proposed.

[0003]

[Problems to be Solved by the Invention] However, NCA
In P, when a dye is mixed and an electric field is removed and a dye color is displayed, light scattering is accompanied, so that the display becomes whitish and blurry. Further, when an electric field is applied to display the color of the white scattering plate on the back surface in a transparent state, the dye is slightly absorbed and it is difficult for the dye to become white. At best white paper 6
The reflectance is about 0%. Next, in the reverse type, the contrast cannot be obtained by putting a white paper on the background. That is, when no electric field is applied, the dye absorbs and scatters white when an electric field is applied, but the white when scattered white is not sufficient. This is because it is difficult for light to reach the background plate due to scattering of the element. Further, in the reverse type, since ultraviolet rays are used when manufacturing the element, the specific resistance of the liquid crystal is lowered.

The present invention has responded to such a demand in the actual situation, and its purpose is to prevent the specific resistance value from being lowered even when it is irradiated with ultraviolet rays, and to mix it with other one or more kinds of liquid crystals. By doing so, it is possible to provide a novel compound which can be driven at a low voltage and which is suitable for obtaining a bright and excellent display element.

[0005]

The present invention is

[0006]

[Chemical 11]

(In the above formula, X is a fluorine atom or a hydrogen atom) and is a biphenyl methacrylate derivative.

The display device of the present invention is a display device in which a liquid crystal and a polymer are oriented and dispersed to each other, and a biphenyl methacrylate derivative is used as at least one component as a precursor for forming the polymer.

[0009]

[Chemical 12]

The constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is at least partially present in the polymer. In a display element in which liquid crystal and polymer are aligned and dispersed with each other, the phase-separated liquid crystal and polymer may be aligned by shearing. Further, in the display device in which the liquid crystal and the polymer are aligned and dispersed with each other, the liquid crystal and the polymer may be phase-separated in a gel network. A display device in which a liquid crystal and a polymer are oriented and dispersed with each other is characterized by containing 1 to 20% of a biphenyl methacrylate derivative as a precursor for forming the polymer. A display element in which a liquid crystal and a polymer are aligned and dispersed with each other is characterized by containing a dichroic dye. Further, it is characterized in that at least one of the liquid crystal and the polymer contains or exists a chiral component. Further, in the display element in which the liquid crystal and the polymer are orientation-dispersed with each other, the orientation direction on the display element surface side is perpendicular to a plane including the main light incident direction and the element surface normal. . Alternatively, the orientation direction of the polymer on the front surface side of the display element is different from the orientation direction of the polymer on the back surface side. Further, in the display element in which the liquid crystal and the polymer are oriented and dispersed with each other, one of the two electrodes sandwiching the liquid crystal and the polymer dispersion layer is a light-reflecting electrode.

Next, a method for producing the biphenyl methacrylate derivative of the present invention will be described.

[0012]

[Table 1]

Step 1 Compound (II) is reacted with methyl iodide with ethanol of potassium hydroxide to obtain Compound (II).

Step 2 A Grignard reagent is prepared from compound (III) and magnesium and reacted with triisopropyl borate in tetrahydrofuran to obtain compound (IV).

Step 3 The compound (IV) and the compound (V) are subjected to a coupling reaction to obtain a compound (VI).

Step 4 Compound (VI) is reduced in acetic acid and hydrobromic acid to obtain compound (VII).

Step 5 Compound (VII) is dissolved in chloroform and triethylamine, and methacryloyl chloride (VIII) is added thereto to effect esterification to obtain compound (I) of the present invention.

[0018]

【Example】

[Example 1] (Compound) A method for producing 3-fluoro-biphenyl-4,4'-diyldimethacrylate.

Step 1 A solution of 20.6 g of potassium hydroxide in 500 ml of ethanol was placed in a flask,
Further, 50 g of 4-bromo-2-fluoro-phenol and 32 ml of methyl iodide are added and the mixture is refluxed for 5 hours. After the reaction, ethanol is distilled off, 100 ml of water is added to the residue, and the mixture is extracted with chloroform. The extract was washed with water, chloroform was distilled off, and the residue was recrystallized from methanol to obtain 4-bromo-2-fluoro-methoxybenzene (35.2 g).

Step 2 Magnesium (5.0 g) was placed in a flask purged with nitrogen, and a solution of 4-bromo-2-fluoro-methoxybenzene (35.2 g) in tetrahydrofuran (150 ml) was slowly added dropwise while stirring with a magnetic stirrer. After the dropping, stirring was continued for 15 hours to prepare a Grignard reagent. The flask prepared is replaced with nitrogen, and a solution of trimethyl borate (39 ml) in tetrahydrofuran (50 ml) is placed therein. The Grignard reagent is added dropwise thereto and stirred for 10 hours. Add 150 ml of 20% aqueous hydrochloric acid to the reaction mixture and stir for a while, then extract the target product with chloroform, wash with water three times, and distill off the chloroform. The residue was recrystallized from methanol and water to obtain 17.5 g of 3-fluoro-4-methoxyphenylboric acid.

Step 3 60 ml of a 2M sodium carbonate aqueous solution and 80 ml of benzene were placed in a flask purged with nitrogen, and 4.4 g of p-bromoanisole and 0.24 g of tetrakistriphenylphosphine palladium were placed.
A solution prepared by dissolving 4.0 g of 3-fluoro-4-methoxyphenylboric acid in 60 ml of ethanol was added dropwise thereto, and the mixture was refluxed for 3 hours. After cooling the reaction solution, extraction with chloroform and washing with water are performed, and then chloroform is distilled off. The residue was recrystallized from acetone and methanol to obtain 3-fluoro-4,4'-dimethoxybiphenyl (4.6 g).

Step 4 In a eggplant-shaped flask, 4.6 g of 3-fluoro-4,4'-dimethoxybiphenyl, 10 ml of hydrobromic acid and 50 ml of acetic acid are placed and refluxed for 20 hours. The reaction solution is cooled to room temperature, filtered and washed with water. The residue was recrystallized in a mixed solvent of acetone and methanol to obtain 2.8 g of 3-fluoro-4,4'-dihydroxybiphenyl.

Step 5 Chloroform (40 ml), 3-fluoro-4,4'-hydroxybiphenyl (2.8 g) and triethylamine (6.1 ml) were placed and dissolved in a nitrogen-purged flask. 3.9 ml of distilled and purified methacryloyl chloride was slowly added dropwise thereto, and the reaction was continued for 3 hours with stirring. After washing the reaction solution with dil.HCl aq., Saturated NaHCO ₃ aq., And water, add methanol to prevent polymerization, and distill off chloroform and methanol. If crystals appear during distillation, take them out and recrystallize them by adding methanol. Further, the product was purified by a silica gel column using chloroform as a developing solvent to obtain 2.3 g of the compound of the present invention, 3-fluoro-biphenyl-4,4'-diyldimethacrylate.

[0024]

[Chemical 13]

The melting point was 105.6 ° C. The infrared absorption spectrum of this compound is shown in FIG.

In the same manner, the following compound was obtained.

3,3'-difluoro-biphenyl-4,
4'-diyl dimethacrylate

[0028]

[Chemical 14]

The melting point was 141.2 ° C. The infrared absorption spectrum of this compound is shown in FIG.

Example 2 (Display Element) As shown in FIG. 3, an electrode 3 made of a transparent electrode film (for example, an ITO film) is formed on glass substrates 1 and 2, and an alignment made of polyimide or the like is formed thereon. Apply the film. Next, rubbing is performed to form the orientation control layer 4, and the glass substrates 1 and 2 are further formed.
Were opposed to each other with a sealant 5 in between, and the following compositions were injected between the glass substrates to prepare a TN type liquid crystal display cell.

In this embodiment, TL202 and MJ91261 are used as the liquid crystal.
(Both manufactured by Merck), S-1011 (manufactured by Merck) as a chiral component, S-344 (manufactured by Mitsui Toatsu Dyes) as a dichroic dye, and 3-fluoro-biphenyl- of the present invention as a polymer precursor. 4,4'-diyl dimethacrylate and 3,
3'-difluoro-biphenyl-4,4'-diyldimethacrylate was used.

The composition measured is TL202 and MJ91261 8: 2.
90.9%, S-1011 0.5%, S-344 3.6% as a mixture. A composition in which 5% of a 2: 1 mixture of biphenyl-4-ylmethacrylate and 3-fluoro-biphenyl-4,4'-diyldimethacrylate of the present invention as a polymer precursor is mixed with this base liquid crystal [5].
And 5% of a 2: 1 mixture of biphenyl-4-yl methacrylate and 3,3′-difluoro-biphenyl-4,4′-diyl dimethacrylate of the present invention [2] as a comparative example. The measurement was carried out on a total of three kinds of compositions [Comparison-1] in which 5% of a 2: 1 mixture of biphenyl-4-ylmethacrylate and biphenyl-4,4'-diyldimethacrylate was mixed. The liquid crystal composition was enclosed in the empty panel described above, and was irradiated with ultraviolet rays to photopolymerize the polymer precursor to phase-separate the liquid crystal and the polymer. The measurement was performed at a cell temperature of 20 ° C and a cell gap of 5 µm.

The display element thus produced was arranged in an optical system as shown in FIG. 4, and a signal having a peak value changed by a 1 KHz square wave was applied. The electro-optical characteristics shown are exhibited. 5 and 6 show liquid crystal compositions [1] and [2] in which the compound of the present invention is mixed.
FIG. 7 shows electro-optical characteristics of a liquid crystal composition [Comparative-1] in which a conventional polymer precursor is mixed. The horizontal axis shows the voltage and the vertical axis shows the reflectance.
0% indicates the brightness when white fine paper is placed instead of the element. By the way, it has been already investigated and found that the reflectance of the element has a rotational viewing angle dependency that the reflectance value changes depending on the incident direction of light even when the incident angle to the panel is constant. Therefore, in order to match the measurement conditions, the reflectance shown here is the value when the panel is fixed at the incident angle at which the reflectance is maximized.

[0034]

[Table 2]

From the above results, by using the liquid crystal composition of the present invention, it was possible to obtain a liquid crystal display device having a driving voltage lower than that of the conventional display device by 1 V or more and a maximum reflectance of 15% or more. Further, the specific resistance of the liquid crystal composition containing the compound of the present invention as a polymer precursor as a display element was 1.6 × 10 ¹¹ Ωcm, and it was possible to maintain a sufficiently large value without any operational problem.

Further, although the TN type liquid crystal display cell is used in the above-mentioned embodiment, the same effect can be obtained when the MIM element, the TFT element or the like is used.

Here, the mixing ratio of the liquid crystal is not limited to the above example, but it is not preferable to increase MJ91261 too much because the specific resistance decreases. On the other hand, if the amount of TL202 is too large, the driving voltage will be high and the degree of scattering will be low, which is not preferable. Even if this liquid crystal composition is mixed with another liquid crystal at an arbitrary ratio, it functions as a display element.

The chiral component can be used without being limited to those shown here. As the chiral component, a polymer precursor having a chiral center can also be used. Also, the mixing ratio is not limited to the amount shown here, but if too much is added, the hysteresis tends to increase.

The dichroic dye can be used without being limited to the ones shown here, but if possible, a dye that absorbs little in the ultraviolet region is preferable. Of course, it is more preferable if the two-color ratio is high. The color of the dye can be arbitrarily selected according to the application. The content of the dye is not limited to the amount shown here, but if it is too large, the dye crystallizes or the display becomes dark.

Although the polymerization initiator was not used here, a photosensitizer can also be used. However,
Use with caution because the specific resistance tends to decrease.

The polymer precursor to be used may be used alone, or part of the phenyl group may be replaced with a substituent such as an alkyl group, a halogen group or a cyano group. further,
Other photopolymerizable polymer precursors may be mixed and used. In particular, when a bifunctional or polyfunctional polymer precursor is mixed, even if the polymer content is reduced, a phenomenon such as image sticking in the display state hardly occurs. The content of the polymer precursor may not be the amount shown here, but if it is too small, the scattering degree becomes weak, and if it is too large, the driving voltage becomes high.

As the polymerization conditions, ultraviolet rays having a length of 300 nm or more were used here, but the polymerization can be performed by using light shorter than this. However, the specific resistance is likely to decrease, so care must be taken in polymerization. The light intensity was set to 3 mW / cm ² , but it is not limited to this. If the light intensity is weak, the polymerization time is lengthened, and if the light intensity is strong, the polymerization time is shortened. However, if the light intensity is too high, the specific resistance tends to decrease. Slight heating during photopolymerization (20-50
Polymerization is easy when (° C.).

For the reflective electrode, aluminum, silver,
Any electrode that reflects light, such as nickel or chromium, can be used. Alternatively, the electrodes may be transparent and a reflective background plate may be used on the back side of the device.

Any method may be used for the alignment treatment as long as it is a treatment for aligning the liquid crystal.

[0045]

As described above, the compound of the present invention or the display device using the same produces a reflective display device having a lower driving voltage and a higher reflectance than the display device using the conventional compounds and compositions. It became possible to do. Further, the compound of the present invention had good compatibility when mixed with any conventional liquid crystal composition. With the compounds of the present invention,
A bright power-saving man-machine interface such as a large-capacity display can be easily and inexpensively manufactured.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum diagram of 3-fluoro-biphenyl-4,4′-diyldimethacrylate obtained in Example 1 of the present invention.

FIG. 2 is an infrared absorption spectrum diagram of 3,3′-difluoro-biphenyl-4,4′-diyldimethacrylate obtained in Example 1 of the present invention.

FIG. 3 is a diagram showing a cross section of a display element in Example 2 of the present invention.

FIG. 4 is a diagram showing an optical system when measuring electro-optical characteristics of a display element in Example 2 of the present invention.

FIG. 5 is a diagram showing electro-optical characteristics of the display element [1] in Example 2 of the present invention.

FIG. 6 is a diagram showing electro-optical characteristics of the display element [2] in Example 2 of the present invention.

FIG. 7 shows a display device in Example 2 of the present invention [comparison-
1] is a diagram showing electro-optical characteristics of [1].

[Explanation of symbols]

 1, 2 Glass substrate 3 Electrode 4 Alignment control layer 5 Sealant 6 Dye 7 Liquid crystal 8 Polymer (9 Reflective background plate when not using reflective electrode) 10 Display element 11 Light source 12 Imaging lens 13 Photoelectron multiplication tube

Claims (10)

[Claims] Claims: (Wherein X is a fluorine atom or a hydrogen atom), a biphenyl methacrylate derivative. 2. In a display device in which a liquid crystal and a polymer are aligned and dispersed with each other, by using a biphenyl methacrylate derivative as at least one component as a precursor for forming the polymer, A polymer-dispersed liquid crystal display device using a biphenyl methacrylate derivative, wherein a constituent element represented by the formula (X is a fluorine atom or a hydrogen atom) is present in at least a part of the polymer. 3. In a display device in which a liquid crystal and a polymer are aligned and dispersed with each other, a method of aligning the phase-separated liquid crystal and the polymer by shearing is used, and at least one biphenyl methacrylate derivative is used as a precursor for forming the polymer. By using it as a component, The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 4. A display device in which a liquid crystal and a polymer are aligned and dispersed with each other, wherein the liquid crystal and the polymer are phase-separated into a gel network, and a biphenyl methacrylate derivative is used as at least one component as a precursor for forming the polymer. By using, The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 5. In a display device in which a liquid crystal and a polymer are orientation-dispersed with each other, as a precursor for forming the polymer: The polymer dispersion type according to claim 2, wherein the biphenyl methacrylate derivative represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is contained in an amount of 1 to 20%. Liquid crystal display device. 6. A display device in which a liquid crystal and a polymer are oriented and dispersed to each other, wherein the liquid crystal contains a dichroic dye, and a biphenyl methacrylate derivative is used as at least one component as a precursor for forming the polymer. [Chemical 6] The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 7. A display device in which a liquid crystal and a polymer are oriented and dispersed to each other, and at least one of the liquid crystal and the polymer contains or exists a chiral component, and at least one biphenyl methacrylate derivative is used as a precursor for forming the polymer. By using it as a component, The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 8. In a display device in which a liquid crystal and a polymer are aligned and dispersed with each other, the alignment direction on the display device surface side is perpendicular to a plane including a main light incident direction and a normal line of the device surface, and By using a biphenyl methacrylate derivative as at least one component as a molecule-forming precursor: The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 9. In a display device in which a liquid crystal and a polymer are aligned and dispersed with each other, the orientation direction on the surface side of the display device is different from the orientation direction of the polymer on the back side of the device, and biphenyl methacrylate is used as a precursor for forming the polymer. By using the derivative as at least one component, The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device. 10. In a display device in which a liquid crystal and a polymer are oriented and dispersed to each other, one of the two electrodes sandwiching the polymer dispersion layer is a light-reflecting electrode, and biphenyl is used as a precursor for forming the polymer. By using a methacrylate derivative as at least one component, The polymer-dispersed type using a biphenyl methacrylate derivative according to claim 2, wherein the constituent element represented by the formula (wherein X is a fluorine atom or a hydrogen atom) is present at least partially in the polymer. Liquid crystal display device.