Anthraquinone compound-containing liquid crystal composition for controlling light, photocured product thereof, and light-controlling element

Abstract

The present invention pertains to: a liquid crystal composition for controlling light that contains, as a dichroic dye, an anthraquinone compound having a specific structure; and a light-controlling element that contains a cured product of said liquid crystal composition for controlling light and exhibits excellent contrast, light-blocking performance, lightfastness, and heat tolerance during current supply. More specifically, the present invention pertains to: a liquid crystal composition for controlling light that contains a compound represented by formula (A) (in the formula, R1 represents a C4-12 alkyl group or a C4-12 alkoxy group, and each R2 independently represents a C6-12 alkyl group), a liquid crystal material, a photocurable compound, and a photoinitiator; and a light-controlling element that is formed by sandwiching a photocured product of said composition between a pair of substrates. ##STR00001##

Claims

1. A liquid crystal composition for controlling light, comprising: a compound represented by the following formula (A) ##STR00012## in the formula, R.sub.1 represents an alkyl group having 4 to 12 carbon atoms or an alkoxy group having 4 to 12 carbon atoms, and each R.sub.2 independently represents an alkyl group having 6 to 12 carbon atoms, the compound represented by the formula (A) being a dichroic dye; a liquid crystal material; a photocurable compound; and a photopolymerization initiator.

2. The liquid crystal composition for controlling light according to claim 1, wherein R.sub.1 in the formula (A) is an alkyl group having 4 to 7 carbon atoms or an alkoxy group having 4 to 7 carbon atoms, and each R.sub.2 is independently an alkyl group having 7 to 10 carbon atoms.

3. The liquid crystal composition for controlling light according to claim 1, wherein R.sub.1 in the formula (A) is an alkyl group having 4 or 5 carbon atoms, and each R.sub.2 is independently an alkyl group having 8 to 10 carbon atoms.

4. The liquid crystal composition for controlling light according to claim 1, wherein R.sub.1 in the formula (A) is an alkyl group having 6 or 7 carbon atoms, and each R.sub.2 is independently an alkyl group having 7 to 9 carbon atoms.

5. The liquid crystal composition for controlling light according to claim 1, comprising one or more dichroic dyes other than the compound represented by the formula (A).

6. A photocured product of the liquid crystal composition for controlling light according to claim 1.

7. A light-controlling element comprising a photocured product of the liquid crystal composition for controlling light according to claim 6 sandwiched between a pair of oppositely disposed substrates, at least one of which is a transparent substrate having thereon a transparent electrode.

8. The light-controlling element according to claim 7, wherein both of the pair of substrates are transparent substrates having thereon a transparent electrode.

9. The liquid crystal composition for controlling light according to claim 2, comprising one or more dichroic dyes other than the compound represented by the formula (A).

10. The liquid crystal composition for controlling light according to claim 3, comprising one or more dichroic dyes other than the compound represented by the formula (A).

11. The liquid crystal composition for controlling light according to claim 4, comprising one or more dichroic dyes other than the compound represented by the formula (A).

12. A photocured product of the liquid crystal composition for controlling light according to claim 2.

13. A photocured product of the liquid crystal composition for controlling light according to claim 3.

14. A photocured product of the liquid crystal composition for controlling light according to claim 4.

15. A photocured product of the liquid crystal composition for controlling light according to claim 5.

16. A photocured product of the liquid crystal composition for controlling light according to claim 9.

17. A photocured product of the liquid crystal composition for controlling light according to claim 10.

18. A photocured product of the liquid crystal composition for controlling light according to claim 11.

19. A light-controlling element comprising a photocured product of the liquid crystal composition for controlling light according to claim 12 sandwiched between a pair of oppositely disposed substrates, at least one of which is a transparent substrate having thereon a transparent electrode.

20. A light-controlling element comprising a photocured product of the liquid crystal composition for controlling light according to claim 13 sandwiched between a pair of oppositely disposed substrates, at least one of which is a transparent substrate having thereon a transparent electrode.

Description

EXAMPLE

(1) Hereinafter, the present invention is specifically described with reference to Examples. The terms part and % in the present description are on a mass standard unless otherwise specified. The maximum absorption wavelength in Examples is a value measured with a spectrophotometer UV-3150 manufactured by Shimadzu Corporation.

Synthesis Example 1 (Synthesis of Compound Represented by Formula (3) as Specific Example)

(2) 2.8 parts of 1-(4-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were added to and dissolved in 35 parts of sulfolane, 0.90 parts of potassium carbonate and 4.4 parts of 4-octyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 1.4 parts of a compound represented by the above formula (3). The maximum absorption wavelength of this compound in toluene was 627 nm.

Synthesis Example 2 (Synthesis of Compound Represented by Formula (6) as Specific Example)

(3) 2.8 parts of 1-(4-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthhraquinone were added to and dissolved in 35 parts of sulfolane, 0.90 parts of potassium carbonate and 4.2 parts of 4-heptyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 1.3 parts of a compound represented by the above formula (6). The maximum absorption wavelength of this compound in toluene was 627 nm.

Synthesis Example 3 (Synthesis of Compound Represented by Formula (13) as Specific Example)

(4) 3.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were added to and dissolved in 35 parts of sulfolane, 0.90 parts of potassium carbonate and 4.2 parts of 4-heptyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 1.1 parts of a compound represented by the above formula (13). The maximum absorption wavelength of this compound in toluene was 627 nm.

Synthesis Example 4 (Synthesis of Compound Represented by Formula (14) as Specific Example)

(5) 3.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were added to and dissolved in 35 parts of sulfolane, 0.90 parts of potassium carbonate and 4.4 parts of 4-octyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 0.9 parts of a compound represented by the above formula (14). The maximum absorption wavelength of this compound in toluene was 627 nm.

Synthesis Example 5 (Synthesis of Compound Represented by Formula (26) as Specific Example)

(6) 2.7 parts of 1-(4-hexylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were added to and dissolved in 35 parts of sulfolane, 0.90 parts of potassium carbonate and 4.6 parts of 4-nonyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 1.3 parts of a compound represented by the above formula (26). The maximum absorption wavelength of this compound in toluene was 627 nm.

Synthesis Example 6 (Synthesis of Compound Represented by Formula (27) as Specific Example)

(7) 2.7 parts of 1-(4-pentylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were added to and dissolved in 40 parts of sulfolane, 0.90 parts of potassium carbonate and 5.0 parts of 4-decyloxyphenol were added thereto, and the mixture was reacted at 130 to 140 C. for 5 hours. After the reaction, the reaction mixture was cooled, methanol was added, and the precipitated crystal was filtered, washed with methanol and water, and then dried. The obtained crude product was purified by column chromatography to obtain 1.2 parts of a compound represented by the above formula (27). The maximum absorption wavelength of this compound in toluene was 627 nm.

Comparative Synthesis Example 1 (Synthesis of Compound for Comparative Example)

(8) A compound represented by Example 6 in JPS62-5941A (a compound represented by the following formula (X)) was obtained by a known synthesis method.

(9) ##STR00011##

Example 1

Production of Liquid Crystal Composition for Controlling Light of Present Invention

(10) 0.015 parts of the compound represented by the above formula (3) obtained in Synthesis example 1, 0.380 parts of isobornyl acrylate (monoacrylate manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.), 0.020 parts of triethylene glycol dimethacrylate (manufactured by SHIN-NAKAMURA CHEMICAL Co., Ltd.), 0.283 parts of 1-cyano-4-n-pentylbiphenyl, 0.139 parts of 1-cyano-4-n-heptylbiphenyl, 0.089 parts of 1-cyano-4-n-octyloxybiphenyl, 0,089 parts of 1-cyano-4-n-penylterphertyl, 0.004 parts of Irgacure TPO (manufactured by BASF SE), 0.004 parts of Irgacure 184 (manufactured by BASF SE), and parts of a spacer agent (Micropearl (registered trademark) SP220 manufactured by SEKISUI CHEMICAL CO., LTD) having a diameter of 20 m were mixed at room temperature to prepare a liquid crystal composition for controlling light of the present invention.

Examples 2 to 6 and Comparative Example 1

Production of Liquid Crystal Composition for Controlling Light of the Present Invention and Comparison

(11) A liquid crystal composition for controlling light of the present invention and a liquid crystal composition for controlling light of comparison were obtained according to Example 1 except that the compound represented by the formula (3) obtained in Synthesis example 1 was changed to the compound represented by the formula (6) obtained in Synthesis example 2, the compound represented by the formula (13) obtained in Synthesis example 3, the compound represented by the formula (14) obtained in Synthesis example 4, the compound represented by the formula (26) obtained in Synthesis example 5, the compound represented by the formula (27) obtained in Synthesis example 6, and the compound represented by the formula (X) obtained in Comparative Synthesis example 1, respectively.

Examples 7 to 12 and Comparative Example 2

Production of Light-Controlling Element of the Present Invention and Comparison

(12) Each of the liquid crystal compositions for controlling light obtained in Examples 1 to 6 and Comparative Example 1 was applied onto an ITO film of a 5 cm square PET film provided with an ITO film using an applicator, and a 5 cm square PET film provided with the same ITO film as described above was superimposed such that the composition layer on the ITO film faced the ITO film. Thereafter, the sample maintained at 23 C. by the thermoplate was set at a position where the light intensity at 365 nm of the LED lamp was 9 mW/cm.sup.2, and light irradiation was performed for 1 minute to photocure the photocurable compound component, thereby obtaining each of the light-controlling element of the present invention and the comparative light-controlling element.

(13) (Calculation of Transmittance Difference of Light-Controlling Element)

(14) For the light-controlling elements obtained in Examples 7 to 12 and Comparative Example 2, the maximum absorption wavelength was measured, and the transmittance difference (transmittance change) was calculated from the measurement result of the transmittance (%) at the maximum absorption wavelength when a 100 V AC voltage (50 Hz sine wave) was applied and when no voltage was applied. The transmittance difference is a value calculated from a difference between the transmittance of the maximum absorption wavelength at the time of voltage application and the transmittance of the maximum absorption wavelength at the time of no voltage application, using each of light-controlling elements produced so that the transmittances of the maximum absorption wavelengths at the time of no voltage application (at the time of light blocking) become equal. As shown in Table 1, it was found that the light-controlling elements of Examples 7 to 12 had a significantly larger transmittance difference between the time of application and the time of non-application than the light-controlling element of Comparative Example 2. In addition, in the light-controlling elements of Examples 7 and 9 to 12, the transmittance difference between the time of application and the time of non-application was even larger than that in the light-controlling element of Example 8 (using the compound represented by the formula (6) obtained in Synthesis example 2).

(15) TABLE-US-00001 TABLE 1 Transmittance difference measurement results Maximum absorption wavelength Transmittance Transmittance Transmittance Light-controlling element (nm) Voltage (0 V) Voltage (100 V) difference Example 7 Compound of formula (3) 635 9 51 42 Example 8 Compound of formula (6) 635 8 48 40 Example 9 Compound of formula (13) 635 9 51 42 Example 10 Compound of formula (14) 635 9 50 41 Example 11 Compound of formula (26) 635 9 51 42 Example 12 Compound of formula (27) 635 10 52 42 Comp. Example 2 Compound of formula (X) 635 8 43 35
(Lightfastness Test of Light-Controlling Element)

(16) A UV cut filter of 400 nm or less was attached to the light-controlling element obtained in each of Examples 7 to 12 and Comparative Example 2, and the absorbance at the maximum absorption wavelength when the light was irradiated for 24 hours with a metal halide lamp having an illuminance of 600 W/m.sup.2 under the condition of 63 C. was measured, and the absorbance retention ((A) %) was calculated. The absorbance retention ((A) %) is defined as follows: when a value of absorbance at 0 hour is A (0) and a value of absorbance after 24 hours is A (24),
(A)%=(A(24)/A(0))100.

(17) The larger the value of A, the better the lightfastness.

(18) As shown in Table 2, it was confirmed that the light-controlling elements of Examples 7 to 12 had a larger absorbance retention than the light-controlling element of Comparative Example 2, and had excellent lightfastness. In addition, the light-controlling elements of Examples 7 and 9 to 12 had a larger absorbance retention than the light-controlling element of Example 8 (using the compound represented by the formula (6) obtained in Synthesis example 2), and had further excellent lightfastness. Among them, the light-controlling elements of Examples 9 to 12 had particularly excellent lightfastness, and in particular, the lightfastness of Examples 11 and 12 was excellent.

(19) TABLE-US-00002 TABLE 2 Lightfastness test results Maximum absorption Absorbance wavelength retention Light-controlling element (nm) (%) Example 7 Compound of formula (3) 635 74.8 Example 8 Compound of formula (6) 635 72.1 Example 9 Compound of formula (13) 635 75.9 Example 10 Compound of formula (14) 635 76.2 Example 11 Compound of formula (26) 635 76.5 Example 12 Compound of formula (27) 635 77.0 Comp. Example 2 Compound of formula (X) 635 61.2

Example 13

Production of Black Color Light-Controlling Element

(20) A black color light-controlling element was produced in the same manner as in Examples 7 to 12 using the liquid crystal composition for controlling light of the present invention prepared in the same manner as in Example 2 except that 0.015 parts of LCD 212 (anthraquinone-based compound, manufactured by Nippon Kayaku Co., Ltd.) and 0.008 pails of LCD 307 (azo-based compound, manufactured by Nippon Kayaku Co., Ltd.) were added. The obtained black color light-controlling element had an average transmittance of 38% at voltage application of 400 to 700 nm and an average transmittance of 9% at no voltage application, showing a high transmittance difference.

(21) The black color light-controlling element obtained in Example 13 had no change in transmittance even after a lapse of 500 hours in the xenon lightfastness test, and was also excellent in lightfastness when exposed to light for a long time. In addition, even when a 100 V AC voltage (50 Hz sine wave) was applied under the condition of 110 C., the transmittance did not change, and the heat tolerance during current supply was also excellent. From these results, it was shown that the black color light-controlling element of Example 13 was a black color liquid crystal light-controlling element having high contrast and high light-blocking performance and having lightfastness and heat tolerance during current supply.

(22) By using the liquid crystal composition of the present invention, a light-controlling liquid crystal element having high contrast, high light-blocking performance, high lightfastness, and high heat tolerance during current supply can he obtained, and the light-controlling liquid crystal element can be suitably used for outdoor building material applications and in-vehicle applications requiring high durability.