Method for processing PHOTOALIGNMENT LAYER in appropriate relative humidity range

[0027] Example 1 The influence of relative humidity on the optical alignment quality of non-composite azo dye film

[0028] In the glove box, the name is tetrasodium 5,5'-((1E,1'E)-(2,2'-disulfonic acid-[1,1'-biphenyl]-4,4'-two The pure sulfate-based azo dye of bis(diazene-2,1-diyl))bis(2-hydroxybenzoic acid) (hereinafter referred to as SD1) is dissolved in dimethylformamide solvent at a concentration of 1% After that, the substrate is evenly covered by spin coating. The azo dye film covering the substrate is soft-baked at 100°C for 10 minutes, then the film is placed in a sealed cabin and removed from the glove box, and then the sealed cabin is exposed to humidity Connect the generator to obtain the required relative humidity inside and balance, then use 5mW/cm 2 Linearly polarized 365nm ultraviolet light irradiation.

[0029] Under different relative humidity, use 5mW/cm 2 While linearly polarized 365nm ultraviolet light is irradiated, the phase retardation of the photo-alignment film is measured in situ with the exposure time. The results are as follows figure 1 Shown.

[0030] Under different relative humidity, use 1J/cm 2 And 3J/cm 2 After the linearly polarized 365nm ultraviolet light is irradiated, the orientation performance of the photo-alignment film is different under different relative humidity, and the phase retardation of the photo-alignment film obtained under the same exposure and different relative humidity is different ( figure 2 ).

[0031] Under different relative humidity, from 1J/cm 2 After the linearly polarized 365nm ultraviolet light is irradiated, the dichroism and order parameters of the alignment layer also depend on the relative humidity ( image 3 ).

[0032] Under different relative humidity (40%, 60%, 80%), the photo-alignment film is at 1J/cm 2 After linearly polarized 365nm ultraviolet radiation, a twisted phase alignment (hereinafter referred to as TN) liquid crystal cell was prepared. The alignment quality of the TN liquid crystal cell under (a) crossed polarizer and (b) parallel polarizer is shown in Figure 4 in. At the same 1J/cm 2 Under UV light conditions, the orientation quality of TN liquid crystal cells is different under different relative humidity.

[0033] Analysis: In order to obtain good alignment quality, the working range of the suitable relative humidity of the non-composite azo dye alignment film is 40-75%, preferably 50%-70%.

[0034] Example 2 Compound of relative humidity on azo dye material, polymer monomer and photoinitiator mixture The influence of the optical alignment quality of the object layer

[0035] The azo dye SD1, polymer monomer 4-(3-acryloxypropoxy)-benzoic acid 2-methyl-1,4-phenyl ester, photoinitiator 1-hydroxy-cyclohexyl-benzene The radical-ketone is dissolved in dimethylformamide solvent. The azo dye and the polymer monomer are mixed in a weight ratio of 1:1, and the weight percentage of the azo dye and the polymer monomer relative to the solvent is 1%. The weight percentage of the photoinitiator relative to the monomer is 20%. Afterwards, by spin coating, the azo dye composite film is evenly covered on the substrate, the substrate is placed in a closed cabin, and the glove box is directly removed. Then connect the airtight cabin with a humidity generator to obtain the required relative humidity inside and balance it, then use 5mW/cm 2 Linearly polarized 365nm ultraviolet light irradiation. Experiments show that through 2J/cm 2 Linearly polarized ultraviolet exposure is sufficient to achieve light orientation and polymerization in one step. After exposure, the alignment film was soft baked at 120°C for 10 minutes to evaporate the solvent.

[0036] Under different relative humidity, use 5mW/cm 2 While linearly polarized 365nm ultraviolet light is irradiated, the phase retardation of the photo-polymerized photo-alignment composite layer is measured in situ with the exposure time. The results are as follows Figure 5 Shown.

[0037] Under different relative humidity, from 2J/cm 2 After the linearly polarized 365nm ultraviolet light is irradiated, the orientation performance of the photo-alignment composite layer of photopolymerization under different relative humidity is different, at 2J/cm 2 The phase delay obtained under the same exposure and different relative humidity is different ( Image 6 ).

[0038] Under different relative humidity, the photo-polymerized photo-alignment composite film is 2J/cm 2 After linearly polarized 365nm ultraviolet radiation, a TN liquid crystal cell was prepared. The alignment quality of the TN liquid crystal cell is shown in the contrast between the bright and dark states under the crossed polarizer. Figure 7 In the same 2J/cm 2 Under UV light conditions, the orientation quality of TN liquid crystal cells is different under different relative humidity. At low humidity, vertical alignment is observed.

[0039] Analysis: In order to obtain a good alignment quality parallel to the surface of the substrate, the proper relative humidity working range of the photopolymerization composite layer needs to be 50%-75%, preferably 55%-70%.

[0040] Example 3 Compound of relative humidity on the mixture of azo dye material, polymer monomer and thermal initiator The influence of the optical alignment quality of the object layer

[0041] The azo dye SD1, the polymer monomer 4-(3-acryloxypropoxy)-benzoic acid 2-methyl-1,4-phenyl ester, and the thermal initiator 2-cyano-2-propane Dodecyl trithiocarbonate, dissolved in dimethylformamide solvent. The azo dye and the polymer monomer are mixed in a weight ratio of 1:1, and the weight percentage of the azo dye and the polymer monomer relative to the solvent is 1%. The weight percentage of the thermal initiator relative to the polymer monomer is 5%. Afterwards, the thermally polymerized azo dye composite film is uniformly covered on the substrate by spin coating, and the substrate is placed in a closed cabin and directly removed from the glove box. Then connect the airtight cabin with a humidity generator to obtain the required relative humidity inside and balance it, then use 5mW/cm 2 Linearly polarized 365nm ultraviolet light irradiation. Experiments show that through 0.1J/cm 2 Linearly polarized ultraviolet exposure is used for light orientation, and then the alignment composite layer is hard baked at 230° C. for 30 minutes for thermal polymerization, which is sufficient to realize the light alignment of the liquid crystal.

[0042] Under different relative humidity, from 5mW/cm 2 While linearly polarized 365nm ultraviolet light is irradiated, the phase retardation of the thermally polymerized photo-alignment composite layer is measured in situ with the exposure time. The results are as follows Figure 8 Shown.

[0043] Under different relative humidity, from 0.1J/cm 2 After irradiated with linearly polarized 365nm ultraviolet light, the orientation performance of the thermally polymerized photo-alignment composite layer under different relative humidity is different, at 0.1J/cm 2 The phase delay obtained under the same exposure and different relative humidity is different ( Picture 9 ).

[0044] Under different relative humidity, the photo-alignment composite film of thermal polymerization is at 0.1J/cm 2 After linearly polarized 365nm ultraviolet radiation and thermal polymerization, a TN liquid crystal cell is prepared. The alignment quality of the TN liquid crystal cell is shown in the contrast between the bright and dark states under the crossed polarizer. Picture 10 In the same 0.1J/cm 2 Under UV light conditions, the orientation quality of TN liquid crystal cells is different under different relative humidity.

[0045] Analysis: The suitable relative humidity operating range of the thermally polymerized composite layer is wider than that of the films described in Examples 1 and 2. In order to obtain a good alignment quality, the relative humidity should be controlled below 75%, preferably below 70%.