WO2022241894A1 - "host-guest" type polarizer and preparation method therefor - Google Patents

Abstract

A "host-guest" type polarizer and a preparation method therefor, relating to the technical field of liquid crystals. The preparation method for the polarizer comprises: dissolving liquid crystal molecules, a dichroic dye, a photoinitiator and a leveling agent in a mixed organic solvent, and stirring and mixing to obtain a "host-guest" mixed solution; and coating the "host-guest" mixed solution on a flexible base film for rubbing alignment, and heating to a clearing point, then annealing, cooling and performing ultraviolet curing to obtain the "host-guest" type polarizer.

Description

A "host-guest" polarizer and its preparation method technical field

The invention belongs to the field of liquid crystal technology, in particular to a "host-guest" polarizer and a preparation method thereof.

Background technique

The "host-guest" type polarizer is made in the form of liquid crystal as the main body and dichroic dye as the guest. Liquid crystal is a special form of matter, between liquid and solid, so it has both the fluidity of liquid and the anisotropy of crystal. Liquid crystals are divided into lyotropic liquid crystals and thermotropic liquid crystals. Lyotropic liquid crystals show a liquid crystal phase when the molecules reach a certain concentration, while thermotropic liquid crystals show a liquid crystal phase within a certain temperature range. As the temperature changes, the molecular arrangement of thermotropic liquid crystals changes and phase transitions occur. These stages mainly include isotropic phase, nematic phase and smectic phase. In the production of "host-guest" polarizers, the liquid crystal is used as the main body to control the molecular arrangement of the whole system to make the whole system in an orderly orientation. polarized light. For example, the patent "Dichroic guest-host polarizer comprising an oriented polymer film" (CN200480032352.X) proposes such an oriented liquid crystal host and a dichroic guest with this orientation, but this polarizer is Produced in a liquid crystal cell, the effect of a flexible polarizer cannot be achieved.

And in different liquid crystal phases, the degree of ordered arrangement of liquid crystal molecules is different, which also affects the ordered orientation of dye molecules in the system, so the performance of polarizers prepared in nematic phase and smectic phase is studied. Under these liquid crystal phases, the regularity of the liquid crystal molecular arrangement is different. Compared with the smectic phase, the nematic phase has a lower viscosity and better molecular fluidity, but the molecular arrangement of the smectic phase has a higher degree of order. Therefore, the system is fixed in the smectic phase to achieve the purpose of increasing the polarization rate.

Contents of the invention

In order to solve the above technical problems, the present invention provides a "host-guest" polarizer and a preparation method thereof. The present invention first synthesizes a reactive liquid crystal with acrylate at one end and a reactive liquid crystal with acrylate at both ends, and this liquid crystal has a smectic phase in a wide temperature range, and this liquid crystal is used as the main body , a dichroic dye as the guest. The dichroic dye as the guest is mainly responsible for the anisotropic absorption of visible light, and the host liquid crystal is responsible for the alignment in a specific direction. The reactive liquid crystal is used for in-situ photopolymerization to produce high polarization on the flexible rubbing alignment base film. "Host-guest" type polarizer.

A preparation method of a "host-guest" type polarizer, comprising the following steps:

S1: Dissolving liquid crystal molecules, dichroic dyes, photoinitiators and leveling agents in a mixed organic solvent, stirring and mixing to obtain a "host-guest" mixed solution;

S2: Coating the above-mentioned "host-guest" mixed solution on the rubbed alignment flexible base film, and heating to the clearing point, then annealing, cooling and UV curing to obtain the "host-guest" polarizer.

In one embodiment of the present invention, the flexible base film is a PET flexible base film.

In one embodiment of the present invention, the flexible base film is a uniaxially stretched flexible base film PET.

In one embodiment of the present invention, the heating temperature in S2 is 100-120°C.

In one embodiment of the present invention, the annealing temperature in S2 is 55-90°C.

In an embodiment of the present invention, the liquid crystal molecules in S1 include liquid crystal molecules A and/or liquid crystal molecules B.

In one embodiment of the present invention, the molecular structure of the liquid crystal molecule A is:

Wherein, n is 4-9; m is 1-2.

In one embodiment of the present invention, the preparation method of the liquid crystal molecule A molecule is:

Step 1: Weigh p-hydroxydibenzoic acid (10-28mmol), hydroxypropyl acrylate (8.0-26mmol) (different carbon chain lengths), triphenylphosphine (10-30mmol) in a 250mL three-necked flask, and then add 50-90mL of redistilled THF, after 10min N ₂ , slowly add diethyl azodicarboxylate (DEAD) (10-30mmol) dropwise under the condition of ice-water bath, and then pass 10min N ₂ protection, react for 3h, the reaction ends Back column chromatography obtains target product 1;

Wherein, m=1-2.

Step 2: Weigh the target product 1 (3.0~10.0mmol), 4-(6-(acryloxy)hexyloxy)benzoic acid (3.0~10.0mmol) (different carbon chain lengths), dicyclohexyl carbon di Imine (DCC) (3.6 ~ 11.0mmol), 4-dimethylaminopyridine (DMAP) (0.6 ~ 1.8mmol) in a 100mL three-necked flask, then add 50 ~ 70mL redistilled THF to the flask, under _N2 The reaction was carried out under protection for 2 days, and after the reaction was completed, the filtrate was distilled under reduced pressure and then recrystallized with ethanol to obtain the product liquid crystal molecule A.

Wherein, n=4-9, m=1-2.

In one embodiment of the present invention, the molecular structure of the liquid crystal molecule B is:

Wherein, q is 4-9, and p is 3-12.

In one embodiment of the present invention, the preparation method of the liquid crystal molecule B molecule is:

Step 1: Weigh p-hydroxydibenzoic acid (5-10mmol) into a 100mL flask, add n-butanol (20mL), add concentrated sulfuric acid (0.5-1.0mL) after dissolving, heat and reflux for 4h, and distill under reduced pressure after the reaction Remove n-butanol (different carbon chain lengths), dissolve in dichloromethane, wash off the remaining concentrated sulfuric acid with 0.3% NaHCO ₃ , dry and distill off the solvent under reduced pressure to obtain product 2.

Wherein, p=3-12.

Step 2: Weigh target product 2 (4.0～12.0mmol), 4-(6-(acryloyloxy)hexyloxy)benzoic acid (4.5～15.0mmol), dicyclohexylcarbodiimide (DCC) ( 5.7 ~ 17.3mmol), 4-dimethylaminopyridine (DMAP) (0.8 ~ 2.4mmol) in a 100mL three-necked flask, then add 50 ~ 90mL redistilled THF in the flask, and react under N ₂ protection for 2 days, After the reaction is completed, after filtration, the filtrate is distilled under reduced pressure and recrystallized by dissolving methanol in acetone to obtain liquid crystal molecule B.

Wherein, q=4-9, p=3-12; m, n, p, q are all integers.

In one embodiment of the present invention, the dichroic dyes in S1 include at least one of Vat Blue, Irgaphor Black X15 and azo dyes.

In one embodiment of the present invention, the photoinitiator in S1 includes at least one of photoinitiator 369, 907, ITX, BDK and benzophenone.

In one embodiment of the present invention, the leveling agent in S1 includes a leveling agent 3600 and/or a leveling agent 361N.

In one embodiment of the present invention, the mixed organic solvent in S1 is obtained by mixing a high-boiling point organic solvent and a low-boiling point organic solvent; the high-boiling point organic solvent refers to a substance with a higher boiling point than the low-boiling point organic solvent.

In one embodiment of the present invention, the high boiling point organic solvent is one or more of cyclohexanone, diethyl carbonate and isophorone.

In one embodiment of the present invention, the low-boiling organic solvent is one or more of toluene, dichloromethane and ethyl acetate.

In one embodiment of the present invention, the mass ratio of the high boiling point organic solvent to the low boiling point organic solvent is 5:5-9:1.

In one embodiment of the present invention, the mass ratio of liquid crystal molecules, dichroic dyes, photoinitiators and leveling agents in S1 is: 92.9-81.7:3-10:4-8:0.1-0.3.

A "host-guest" polarizer.

The above technical solution of the present invention has the following advantages compared with the prior art:

The invention synthesizes a liquid crystal with a smectic phase, and has a wide temperature range, and uses such a liquid crystal as the main body to provide a highly ordered orientation for the host-guest system.

The present invention adopts dichroic black dye as the object, because the molecular structure of the black dye has a high aspect ratio, anisotropic absorption occurs.

The present invention is coated on the flexible rubbing alignment base film, mainly by controlling the degree of orientation, temperature, leveling, thickness of the film and the amount of dichroic dye doping to perform in-situ photocuring to obtain a flexible linear polarizer. This material can be used in flexible displays.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

Fig. 1 is the polarization diagram of the mixed system of liquid crystal A3/dichroic black dye/photoinitiator/leveling agent of the present invention.

Fig. 2 is a DSC curve diagram of the liquid crystal molecule A3 of the present invention.

Fig. 3 is a DSC curve diagram of the liquid crystal molecule A4 of the present invention.

Fig. 4 is a polarized ultraviolet-visible spectrum diagram of a polarizer before and after curing obtained from the liquid crystal A3/dichroic black dye/photoinitiator/leveling agent system in Example 5 of the present invention.

Fig. 5 is a polarized ultraviolet-visible spectrum diagram of a polarizer before and after curing obtained from the liquid crystal A3/dichroic black dye/photoinitiator/leveling agent system in Example 5 of the present invention.

Fig. 6 is a diagram showing the ordered orientation of liquid crystal molecules and dye molecules observed under a polarizing microscope on the polarizer prepared in Example 5 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Table 1 Recipe table

the

liquid crystal molecules

dichroic dye

Photoinitiator

leveling agent

the	(wt%)	(wt%)	(wt%)	(wt%)
Recipe 1	87.7	4	8	0.3
Recipe 2	86.7	5	8	0.3
Recipe 3	85.7	6	8	0.3
Recipe 4	84.7	7	8	0.3
Recipe 5	83.7	8	8	0.3
Recipe 6	82.7	9	8	0.3
Recipe 7	81.7	10	8	0.3

Example 1

Material 1 was prepared comprising the following structure:

Liquid Crystal Molecule A1

Photoinitiator 369

(1) Synthesis of liquid crystal molecule A1

Weigh p-hydroxydibenzoic acid (4.0g, 18.7mmol), hydroxypropyl acrylate (2.21g, 16.9mmol), triphenylphosphine (5.39g, 20.53mmol), in a 250mL three-necked flask, then add 100mL of heavy After steaming THF for 10min under _N2 , slowly add diethyl azodicarboxylate (DEAD) (3.58g, 20.53mmol) dropwise under ice-water bath conditions, and then pass through _10minN2 for protection, react for 3h, and perform column chromatography after the reaction method to obtain the target product. Weigh the product (2g, 6.13mmol), 4-(6-(acryloyloxy)hexyloxy)benzoic acid (2.45g, 6.75mmol), dicyclohexylcarbodiimide (DCC) (1.52g, 4.36 mmol), 4-dimethylaminopyridine (DMAP) (0.14g, 1.22mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, react under N ₂ protection for 2 days, filter after the reaction , The filtrate was distilled under reduced pressure and then recrystallized with ethanol to obtain the product.

(2) Preparation of materials

Weigh liquid crystal molecule A1 (8.72) and dichroic black dye Irgaphor Black X15 (0.45g), photoinitiator 369 (0.80g) and leveling agent 3600 (0.03g) are dissolved in cyclohexanone and ethyl acetate (4 : 1) in (40g) mixed solvent, make solid content and be 20% " host-guest " mixed solution. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 110°C and heat to the clearing point, then anneal at 70°C, and finally cool slowly to 55°C for UV curing to obtain polarizers with different thicknesses. Then polarizers are prepared according to different mass ratios of dichroic black dyes.

Different mass proportions of liquid crystal molecules, dichroic dye photoinitiators and leveling agents are mixed by the above method to obtain different polarizers. The formula is shown in Table 1.

Example 2

Prepare material 2 comprising the following components

Liquid Crystal Molecule A1

Liquid crystal molecule B1

Photoinitiator 369

(1) Preparation of liquid crystal molecule A1

Same as the synthetic steps of liquid crystal molecule A1 in embodiment 1

(2) Preparation of liquid crystal molecule B1

Weigh p-hydroxydibenzoic acid (2.0g) and a 100mL flask, add n-butanol (20mL), add concentrated sulfuric acid (0.5mL) after dissolving, heat and reflux for 4h, remove n-butanol by distillation under reduced pressure after the reaction is completed, dissolve In dichloromethane, wash off the remaining concentrated sulfuric acid with 0.3% NaHCO ₃ , dry and distill off the solvent under reduced pressure to obtain the product. Weigh the product (2.0g, 8.26mmol), 4-(6-(acryloyloxy)hexyloxy)benzoic acid (2.65g, 9.08mmol), dicyclohexylcarbodiimide (DCC) (2.39g, 11.56mmol), 4-dimethylaminopyridine (DMAP) (0.2g, 1.65mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, and react under N ₂ protection for 2 days, after the reaction ends After filtration, the filtrate was distilled under reduced pressure and recrystallized by dissolving methanol in acetone to obtain the product.

(3) Preparation of materials

Weigh liquid crystal molecule A1 (4.36g) and liquid crystal molecule B1 (4.36g) (5:5) as liquid crystal main body and dichroic black dye Irgaphor Black X15 (0.45g), photoinitiator 369 (0.80g) and leveling Agent 3600 (0.03g) was dissolved in a mixed solvent of cyclohexanone and ethyl acetate (4:1) (40g) to prepare a "host-guest" mixed solution with a solid content of 20%. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 120°C and heat to the clearing point, then anneal at 90°C, and finally cool slowly to 80°C for UV curing to obtain polarizers with different thicknesses. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

Example 3

Prepare material 3 comprising the following components

Liquid Crystal Molecule A2

Photoinitiator 907

PhotoinitiatorITX

(1) Preparation of liquid crystal molecule A2

Weigh p-hydroxydibenzoic acid (4.0g, 18.7mmol), hydroxybutyl acrylate (2.45g, 16.97mmol), triphenylphosphine (5.39g, 20.53mmol), in a 250mL three-necked flask, then add 100mL of heavy Diethyl azodicarboxylate (DEAD) (3.58g, 20.53mmol) was slowly added dropwise under ice-water bath conditions after steaming THF for 10min under N ₂ , and then passed through N ₂ for 10min for protection, and reacted for 3h. After the reaction, the column layer analysis method to obtain the target product. Weigh the product (2g, 5.88mmol) 4-(6-(acryloyloxy)hexyloxy)benzoic acid (1.89g, 6.47mmol), dicyclohexylcarbodiimide (DCC) (1.46g, 7.06mmol ), 4-dimethylaminopyridine (DMAP) (0.14g, 1.17mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, and react under N ₂ protection for 2 days, after the reaction finishes and filters , The filtrate was distilled under reduced pressure and then recrystallized with ethanol to obtain the product.

(2) Preparation of materials

Weigh liquid crystal molecule A2 (8.72g) and dichroic black dye Irgaphor Black X15 (0.45g), photoinitiator 369 (0.4g) and photoinitiator ITX (0.4g) (1:1) and leveling agent 3600 ( 0.03g) was dissolved in a mixed solvent of cyclohexanone and ethyl acetate (4:1) (40g) to prepare a "host-guest" mixed solution with a solid content of 20%. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 110°C and heat to the clearing point, then anneal at 70°C, and finally cool slowly to 55°C for UV curing to obtain polarizers with different thicknesses. Then polarizers are prepared according to different mass ratios of dichroic black dyes. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

Example 4

Prepare material 4 comprising the following components

Liquid Crystal Molecule A2

Liquid crystal molecule B1

Photoinitiator 369

(1) Preparation of liquid crystal molecule A2

Same as the synthetic steps of embodiment 3 liquid crystal molecules A2

(2) Preparation of liquid crystal molecule B1

Same as the synthetic steps of embodiment 2 liquid crystal molecules B1

(3) Preparation of materials

Weigh liquid crystal molecule A2 (5.23g) and liquid crystal molecule B1 (3.49g) (6:4) as liquid crystal main body and dichroic black dye Irgaphor Black X15 (0.45g), photoinitiator 369 (0.80g) and leveling Agent 3600 (0.03g) was dissolved in a mixed solvent of cyclohexanone and ethyl acetate (4:1) (40g) to prepare a "host-guest" mixed solution with a solid content of 20%. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 120°C and heat it to the clearing point, then anneal at 90°C, and finally cool slowly to 75°C for UV curing to obtain polarizers with different thicknesses. Then polarizers were prepared by changing dichroic black dyes with different mass ratios. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

Example 5

Prepare material 5 comprising the following components

Liquid Crystal Molecule A3

Photoinitiator 369

(1) Preparation of liquid crystal molecule A3

Weigh p-hydroxydibenzoic acid (4.0g, 18.7mmol), hydroxypropyl acrylate (2.21g, 16.9mmol), triphenylphosphine (5.39g, 20.53mmol), in a 250mL three-necked flask, then add 100mL of heavy After steaming THF for 10min under _N2 , slowly add diethyl azodicarboxylate (DEAD) (3.58g, 20.53mmol) dropwise under ice-water bath conditions, and then pass through _10minN2 for protection, react for 3h, and perform column chromatography after the reaction method to obtain the target product. Weigh the product (2g, 5.88mmol), 4-(11-(acryloyloxy) undecyloxy) benzoic acid (2.44g, 6.47mmol), dicyclohexylcarbodiimide (DCC) (1.56g, 7.06mmol), 4-dimethylaminopyridine (DMAP) (0.14g, 1.17mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, and react under N ₂ protection for 2 days, after the reaction ends After filtration, the filtrate was distilled under reduced pressure and then recrystallized with ethanol to obtain the product.

(2) Preparation of materials

Weigh liquid crystal molecule A3 (8.87g) and dichroic black dye Irgaphor Black X15 (0.70g), photoinitiator (0.8g) and leveling agent 3600 (0.03g) are dissolved in cyclohexanone and ethyl acetate (4 : 1) in (40g) mixed solvent, make solid content and be 20% " host-guest " mixed solution. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 110°C and heat to the clearing point, then anneal at 70°C, and finally cool slowly to 55°C for UV curing to obtain polarizers with different thicknesses. Then polarizers are prepared according to different mass ratios of dichroic black dyes. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, through the test of polarized UV-visible spectrum, the transmittance in the vertical and horizontal directions can be tested, and the DOP (polarization rate) of the polarizer can be calculated. The results are shown in Figure 4-6 .

Example 6

Prepare material 6 comprising the following components

Liquid Crystal Molecule A3

Liquid Crystal Molecule B2

Photoinitiator 369

(1) Preparation of liquid crystal molecule A3

Same as the synthetic steps of embodiment 3 liquid crystal molecule A3

(2) Preparation of liquid crystal molecule B2

Weigh p-hydroxydibenzoic acid (2.0g) and a 100mL flask, add n-butanol (20mL), add concentrated sulfuric acid (0.5mL) after dissolving, heat and reflux for 4h, remove n-butanol by distillation under reduced pressure after the reaction is completed, dissolve In dichloromethane, wash off the remaining concentrated sulfuric acid with 0.3% NaHCO ₃ , dry and distill off the solvent under reduced pressure to obtain the product. Weigh the product (2.0g, 8.26mmol), 4-(11-(acryloyloxy) undecyloxy) benzoic acid (3.29g, 9.08mmol), dicyclohexylcarbodiimide (DCC) (2.05g , 9.91mmol), 4-dimethylaminopyridine (DMAP) (0.2g, 1.65mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, react under N ₂ protection for 2 days, and the reaction ends After filtration, the filtrate was distilled under reduced pressure and recrystallized by dissolving methanol in acetone to obtain the product.

(3) Preparation of materials

Weigh liquid crystal molecule A3 (6.07g) and liquid crystal molecule B2 (2.60g) (7:3) as liquid crystal main body and dichroic black dye Irgaphor Black X15 (0.50g), photoinitiator (0.80g) and leveling agent 361N (0.03g) was dissolved in a mixed solvent of cyclohexanone and ethyl acetate (4:1) (40g) to prepare a "host-guest" mixed solution with a solid content of 20%. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 120°C and heat to the clearing point, then anneal at 80°C, and finally cool slowly to 65°C for UV curing to obtain polarizers with different thicknesses. Then polarizers were prepared by changing dichroic black dyes with different mass ratios. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

Example 7

Prepare material 7 comprising the following components

Liquid Crystal Molecule A4

Photoinitiator 369

(1) Preparation of liquid crystal molecule A4

Weigh p-hydroxydibenzoic acid (4.0g, 18.7mmol), hydroxybutyl acrylate (2.45g, 16.97mmol), triphenylphosphine (5.39g, 20.53mmol), in a 250mL three-necked flask, and then add 100mL of heavy After steaming THF for 10min under _N2 , slowly add diethyl azodicarboxylate (DEAD) (3.58g, 20.53mmol) dropwise under ice-water bath conditions, and then pass through _10minN2 for protection, react for 3h, and perform column chromatography after the reaction method to obtain the target product. Weigh the product (2g, 5.88mmol) 4-(6-(acryloyloxy)hexyloxy)benzoic acid (1.89g, 6.47mmol), dicyclohexylcarbodiimide (DCC) (1.46g, 7.06mmol ), 4-dimethylaminopyridine (DMAP) (0.14g, 1.17mmol) in a 100mL three-necked flask, then add 70mL of redistilled THF in the flask, and react under N ₂ protection for 2 days, after the reaction is completed and filtered, the The filtrate was distilled under reduced pressure and recrystallized from ethanol to obtain the product.

(2) Preparation of materials

Weigh liquid crystal molecule A4 (8.92g) and dichroic black dye Irgaphor Black X15 (0.45g), photoinitiator (0.6g) and leveling agent (0.03g) are dissolved in cyclohexanone and ethyl acetate (4: 1) In (40g) mixed solvent, make a solid content of 20% "host-guest" mixed solution. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 110°C and heat to the clearing point, then anneal at 70°C, and finally cool slowly to 55°C for UV curing to obtain polarizers with different thicknesses. Then polarizers are prepared according to different mass ratios of dichroic black dyes. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

Example 8

Prepare material 8 comprising the following components

Liquid Crystal Molecule A4

Liquid Crystal Molecule B2

Photoinitiator 369

(1) Preparation of liquid crystal molecule A4

Same as the synthetic steps of embodiment 7 liquid crystal molecule A4

(2) Preparation of liquid crystal molecule B2

Same as the synthetic steps of embodiment 6 liquid crystal molecule B2

(3) Preparation of materials

Weigh liquid crystal molecule A4 (6.94g) and liquid crystal molecule B2 (1.73g) (8:2) as liquid crystal main body and dichroic black dye Irgaphor Black X15 (0.50g), photoinitiator 369 (0.8g) and leveling Agent 3600 (0.03g) was dissolved in a mixed solvent of cyclohexanone and ethyl acetate (4:1) (40g) to prepare a "host-guest" mixed solution with a solid content of 20%. The solution was coated onto a rubbed oriented flexible base film by wire bar. Evaporate the solvent at 110°C and heat to the clearing point, then anneal at 70°C, and finally cool slowly to 55°C for UV curing to obtain polarizers with different thicknesses. Then polarizers were prepared by changing dichroic black dyes with different mass ratios. By taking POM photos to observe the ordered orientation of liquid crystal molecules and dye molecules, the transmittance in the vertical and horizontal directions can be tested through the test of the polarized ultraviolet-visible spectrum, and the DOP (polarization rate) of the polarizer can be calculated.

test case

The polarizing plate prepared in Example 5 was subjected to polarized ultraviolet-visible light detection, and the results are shown in Fig. 4 and Fig. 5. From the information in the figure, it can be seen that: (liquid crystal A3 (84.7wt%)/dichroic black dye (7wt%)/photoinitiated (8wt%)/leveling agent (0.3wt%) system obtained before and after the polarizing UV-visible spectrum of the polarizer after curing); Fig. 4 is the polarization performance test before the curing of the polarizer prepared by this mass ratio, and the polarization rate can be It reaches 92%; after it is cured by ultraviolet rays, the obtained polarizer has a slight decrease in the polarization rate due to the shrinkage of the system after curing, and the polarization rate is 82%. The polarization rate can be further improved by increasing the thickness of the film, the content of the dye, and some other methods.

The polarizer prepared in Example 5 was observed under a polarizing microscope for the orderly orientation of liquid crystal molecules and dye molecules. The POM photos when the long axis direction of the molecule is vertical, 45° and parallel can clearly observe the ordered orientation and the change of light and dark.

Apparently, the above-mentioned embodiments are only examples for clearly explaining, and are not intended to limit the implementation. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in various forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (10)

1. A preparation method of a "host-guest" type polarizer, characterized in that: comprising the following steps:

   S1: Dissolving liquid crystal molecules, dichroic dyes, photoinitiators and leveling agents in a mixed organic solvent, stirring and mixing to obtain a "host-guest" mixed solution;

   S2: Coating the "host-guest" mixed solution on the rubbing-oriented flexible base film, and heating to the clearing point, then annealing, cooling and UV curing to obtain the "host-guest" polarizer.
2. The preparation method according to claim 1, wherein the liquid crystal molecules in S1 are liquid crystal molecules A and/or liquid crystal molecules B;

   The molecular structure of the liquid crystal molecule A is:

   

   Wherein, n is 4-9; m is 1-2;

   The molecular structure of the liquid crystal molecule B is:

   

   Among them, q is 4-9, p is 3-12;

   m, n, p, and q are all integers.
3. The preparation method according to claim 1, characterized in that: the dichroic dye in S1 is selected from one or more of Vat Blue, IrgaphorBlack X15 and azo dyes.
4. The preparation method according to claim 1, characterized in that: the photoinitiator in S1 is selected from one or more of photoinitiators 369, 907, ITX, BDK and benzophenone.
5. The preparation method according to claim 1, characterized in that: the leveling agent in S1 is leveling agent 3600 and/or leveling agent 361N.
6. The preparation method according to claim 1, characterized in that: the mixed organic solvent in S1 is obtained by mixing a high boiling point organic solvent and a low boiling point organic solvent.
7. The preparation method according to claim 6, characterized in that: the high boiling point organic solvent is one or more of cyclohexanone, diethyl carbonate and isophorone; the low boiling point organic solvent is toluene , one or more of dichloromethane and ethyl acetate.
8. The preparation method according to claim 6, characterized in that: the mass ratio of the high-boiling point organic solvent to the low-boiling point organic solvent is 5:5-9:1.
9. The preparation method according to claim 1, characterized in that: the mass ratio of liquid crystal molecules, dichroic dyes, photoinitiators and leveling agents in S1 is 92.9-81.7:3-10:4-8:0.1- 0.3.
10. The "host-guest" polarizer obtained by the preparation method according to any one of claims 1-9.

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