A gray polymer dispersed liquid crystal film and preparation method thereof

Abstract

The present invention discloses a gray polymer dispersed liquid crystal film and a preparation method thereof. The preparation method comprises the following steps: (1) preparing a blue-violet dye liquid crystal A, an orange dye liquid crystal B, and a blue dye liquid crystal C; (2) mixing the blue-violet dye liquid crystal A, the orange dye liquid crystal B, and the blue dye liquid crystal C uniformly to form a gray dye liquid crystal; (3) uniformly mixing the gray dye liquid crystal with a polymer monomer composition to form an isotropic liquid crystal mixture at room temperature; (4) mixing the liquid crystal mixture with glass microbeads and sandwiching them between two transparent conductive films, rolling to form a liquid crystal film; and then curing the liquid crystal film. The gray polymer dispersed liquid crystal film has a large total light transmittance difference between the power-on state and the power-off state; so that when it changes between the transparent state and the frosted state, it has a significant color depth change, which can meet high-demand application scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of liquid crystal film preparation, and in particular to a gray polymer dispersed liquid crystal film and a preparation method thereof. Background Art

[0002] Polymer dispersed liquid crystal film is a film formed by micron-sized liquid crystal droplets embedded in a continuous polymer matrix. Under the control of an electric field, the external field responsiveness of liquid crystal molecules is utilized, and according to the matching degree of the refractive index of the liquid crystal droplets and the polymer matrix, the light scattering state and the transparent state can be switched between each other.

[0003] Chinese patent 201210560826.4 discloses a method for preparing a colored polymer dispersed liquid crystal film, in which anthraquinone dyes or azo dyes are mixed into liquid crystal raw materials, and then mixed evenly with polymer monomers to prepare colored polymer dispersed liquid crystal films. The dye is used as the guest and the liquid crystal is used as the host. The guest-host effect is used to make the dye molecules flip along with the flipping of the liquid crystal molecules under the action of the electric field, so that the color of the polymer dispersed liquid crystal film changes between the transparent state and the frosted state. In this patent, the weight ratio of liquid crystal dispersed black (azo dye) to liquid crystal raw materials is 1:99, heated at 60℃ and stirred for 10 hours, so that the liquid crystal and dye are evenly mixed; epoxy resin, curing agent glass beads and liquid crystal are evenly mixed in a ratio of 1:1:0.5:1, sandwiched between two ITO-coated transparent conductive films, and rolled evenly; heated at 80℃ for 6 hours to cure, and a black PDLC film is obtained.

[0004] The invention patent has a superposition of strong absorption and scattering states (frosted state) in the non-powered state, and a superposition of weak absorption and transparent states (transparent state) in the powered state. By turning the electric field on and off, the invention realizes that the color changes when changing between the transparent state and the frosted state (the depth of the color changes).

[0005] However, the inventors found in their research that the total light transmittance difference between the power-on state and the power-off state of the colored polymer dispersed liquid crystal film prepared by the above patented method is not large enough, which leads to the lack of significant color depth change when it changes between the transparent state and the frosted state; it is difficult to meet high-demand application scenarios. Therefore, it is of great application value to provide a dispersed liquid crystal film with a large total light transmittance difference between the power-on state and the power-off state. Summary of the invention

[0006] In order to overcome at least one of the technical problems existing in the prior art, the present invention first provides a method for preparing a gray polymer dispersed liquid crystal film.

[0007] The technical solution of the present invention is:

[0008] A method for preparing a gray polymer dispersed liquid crystal film comprises the following steps:

[0009] (1) preparing blue-violet dye liquid crystal A, orange dye liquid crystal B, and blue dye liquid crystal C;

[0010] (2) mixing the blue-violet dye liquid crystal A, the orange dye liquid crystal B and the blue dye liquid crystal C to form a gray dye liquid crystal;

[0011] (3) uniformly mixing the gray dye liquid crystal and the polymer monomer composition to form an isotropic liquid crystal mixture at room temperature;

[0012] (4) The liquid crystal mixed liquid and glass beads are mixed and sandwiched between two transparent conductive films, and rolled to form a liquid crystal film; the liquid crystal film is then cured to obtain the gray polymer dispersed liquid crystal film.

[0013] The inventors discovered in their research that bluish-purple dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are evenly mixed to form gray dye liquid crystal; then the gray dye liquid crystal is mixed with a polymer monomer to prepare a gray polymer dispersed liquid crystal film; it has a large difference in total light transmittance between the power-on state and the power-off state; so that when it changes between the transparent state and the frosted state, it has a significant change in color depth, which can meet high-demand application scenarios.

[0014] The inventors need to explain here that the step of uniformly mixing the bluish-violet dye liquid crystal A, the orange dye liquid crystal B and the blue dye liquid crystal C to form a gray dye liquid crystal is very critical; only when the bluish-violet dye liquid crystal A, the orange dye liquid crystal B and the blue dye liquid crystal C are uniformly mixed to form a gray dye liquid crystal; and then the gray dye liquid crystal is mixed with a polymer monomer to prepare a gray polymer dispersed liquid crystal film; it has a larger difference in total light transmittance between the power-on state and the power-off state.

[0015] Preferably, the preparation method of the blue-violet dye liquid crystal A in step (1) is: mixing a blue-violet dye (liquid crystal manufacturer model 3YA-004-05) into liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form a blue-violet dye liquid crystal A;

[0016] Wherein, the blue-violet dye is a triazo blue-violet dye;

[0017] The weight ratio of the blue-violet dye to the liquid crystal 1 is 1:99 to 6:94;

[0018] Preferably, the preparation method of the orange dye liquid crystal B in step (1) is: mixing orange dye (liquid crystal manufacturer model 3YA-105-05) into liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form orange dye liquid crystal B;

[0019] Wherein, the orange dye is a naphthyl-substituted anthraquinone orange dye;

[0020] The weight ratio of the orange dye to the liquid crystal 1 is 1:99 to 6:94.

[0021] Preferably, the preparation method of the blue dye liquid crystal C in step (1) is: mixing a blue dye (liquid crystal manufacturer model 3YA-005-05) into liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form a blue dye liquid crystal B;

[0022] Wherein, the blue dye is a phenyl-substituted anthraquinone blue dye;

[0023] The weight ratio of the blue dye to the liquid crystal 1 is 1:99 to 6:94.

[0024] Preferably, the liquid crystal 1 is a nematic mixed crystal (liquid crystal manufacturer model 3YP-601).

[0025] Preferably, the weight ratio of the purple liquid crystal A, the orange liquid crystal B, and the blue liquid crystal C in step (2) is (0.35-0.48):(0.35-0.48):(0.15-0.20).

[0026] Preferably, liquid crystal 2 is also added in step (2); blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are uniformly mixed with liquid crystal 2 to form gray dye liquid crystal.

[0027] Further preferably, the weight ratio of the purple liquid crystal A, orange liquid crystal B, blue liquid crystal C, and liquid crystal 2 in step (2) is (0.28-0.38):(0.28-0.38):(0.12-0.15):(0.18-0.22);

[0028] Preferably, the liquid crystal 2 is a nematic mixed crystal (liquid crystal manufacturer model 3YP-502).

[0029] The inventors were further surprised to find that by adding liquid crystal 2 in step (2); mixing blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C with liquid crystal 2 to form gray dye liquid crystal; and then mixing the gray dye liquid crystal with polymer monomers to prepare a gray polymer dispersed liquid crystal film; the difference in total light transmittance between the power-on state and the power-off state was further increased.

[0030] Preferably, the weight ratio of the gray dye liquid crystal to the polymer monomer composition in step (3) is 4:6 to 6:4.

[0031] Preferably, the polymer monomer composition in step (3) is a mixture of polymer monomers and initiators.

[0032] More preferably, the polymer monomers are composed of methyl methacrylate and epoxy acrylic resin in a weight ratio of 7:3 to 8:2.

[0033] More preferably, the weight ratio of the initiator to the polymer monomer is 0.3:99.7 to 3:97.

[0034] Further preferably, the initiator is selected from one of initiators 819, TPO and 184, or a mixture of more than one of them.

[0035] Preferably, in step (4), the weight ratio of glass beads to the liquid crystal mixture is 0.1-5:99.9-95.

[0036] More preferably, the particle size of the glass microbeads is 5 μm-30 μm.

[0037] Preferably, the conductive layer of the transparent conductive film in step (4) may be indium tin oxide, nanosilver, graphene, polyaniline or polythiophene.

[0038] Preferably, the curing in step (4) is performed by ultraviolet light curing.

[0039] Further preferably, the UV curing time is 5 seconds to 5 minutes, and the UV intensity is 2mw / cm 2 ~30mw / cm 2 ).

[0040] The present invention also provides a gray polymer dispersed liquid crystal film prepared by the above preparation method.

[0041] Beneficial effects: The present invention provides a new method for preparing a gray polymer dispersed liquid crystal film; the method uniformly mixes blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C to form a gray dye liquid crystal; then mixes the gray dye liquid crystal with a polymer monomer to prepare a gray polymer dispersed liquid crystal film; the gray polymer dispersed liquid crystal film has a large difference in total light transmittance between the power-on state and the power-off state; when it changes between the transparent state and the frosted state, it has a significant change in color depth, which can meet high-demand application scenarios. In particular, in step (2), liquid crystal 2 is added; it can further increase the difference in total light transmittance of the prepared gray polymer dispersed liquid crystal film between the power-on state and the power-off state; thereby making the prepared gray polymer dispersed liquid crystal film more concealed in the frosted state and clearer and more transparent in the transparent state. DETAILED DESCRIPTION

[0042] The present invention is further explained below in conjunction with specific examples, but the examples do not limit the present invention in any form.

[0043] Example 1 Preparation of Gray Polymer Dispersed Liquid Crystal Film

[0044] (1) A blue-violet dye (liquid crystal manufacturer model 3YA-004-05) is mixed into liquid crystal 1, and the liquid crystal raw materials are heated and stirred to be evenly colored to form a blue-violet dye liquid crystal A; the blue-violet dye is a triazo blue-violet dye; the weight ratio of the blue-violet dye to the liquid crystal 1 is 5:95; the liquid crystal 1 is a nematic phase liquid crystal (liquid crystal manufacturer model 601).

[0045] An orange dye (liquid crystal manufacturer model 3YA-105-05) is mixed into liquid crystal 1, and heated and stirred to uniformly color the liquid crystal raw material to form an orange dye liquid crystal B; the orange dye is a naphthyl-substituted anthraquinone orange dye; the weight ratio of the orange dye to the liquid crystal 1 is 5:95; the liquid crystal 1 is a nematic phase mixed crystal (liquid crystal manufacturer model 3YP-601).

[0046] A blue dye (liquid crystal manufacturer model 3YA-005-05) is mixed into liquid crystal 1, and heated and stirred to evenly color the liquid crystal raw material to form a blue dye liquid crystal C; the blue dye is a phenyl-substituted anthraquinone blue dye; the weight ratio of the blue dye to the liquid crystal 1 is 5:95; the liquid crystal 1 is a nematic phase mixed crystal (liquid crystal manufacturer model 601).

[0047] (2) The blue-violet liquid crystal A, orange liquid crystal B, and blue liquid crystal C are mixed uniformly in a certain proportion to form a gray dye liquid crystal; the weight ratio of the purple liquid crystal A, orange liquid crystal B, and blue liquid crystal C is 0.38:0.45:0.17.

[0048] (3) The gray liquid crystal and the polymer monomer composition are uniformly mixed to form an isotropic liquid crystal mixture at room temperature. The polymer monomer composition is a mixture of polymer monomers (methyl methacrylate and epoxy acrylic resin) and an initiator. The weight ratio of the gray liquid crystal to the polymer monomer composition is 48.5:51.5; the weight ratio of the methyl methacrylate to the epoxy acrylic resin is 7:3; the initiator is initiator TPO; and the weight ratio of the initiator to the polymer monomer is 0.7:99.3.

[0049] (4) mixing the liquid crystal mixture with glass beads, sandwiching the mixture between two transparent conductive films, and rolling to form a liquid crystal film; curing the liquid crystal film with ultraviolet light to form a gray polymer dispersed liquid crystal film;

[0050] The weight ratio of the glass beads to the liquid crystal mixture is 0.3:99.79; the transparent conductive film conductive layer can be indium tin oxide; the particle size of the glass beads is: 18 μm;

[0051] The UV curing time is 40 seconds, and the UV intensity is 10mw / cm 2 .

[0052] Example 2 Preparation of Gray Polymer Dispersed Liquid Crystal Film

[0053] The difference between Example 2 and Example 1 is that in step (2), liquid crystal 2 is further added; blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are uniformly mixed with liquid crystal 2 to form gray dye liquid crystal. The rest is the same as Example 1.

[0054] Step (2) is specifically as follows:

[0055] (2) The blue-violet liquid crystal A, orange liquid crystal B, blue liquid crystal C, and liquid crystal 2 are mixed uniformly in a certain proportion to form a gray dye liquid crystal; the weight ratio of the purple liquid crystal A, orange liquid crystal B, blue liquid crystal C, and liquid crystal 2 is 0.3:0.36:0.14:0.2; the liquid crystal 2 is a nematic phase mixed crystal (liquid crystal manufacturer model 3YP-502).

[0056] Example 3 Preparation of Gray Polymer Dispersed Liquid Crystal Film

[0057] (1) A blue-violet dye (liquid crystal manufacturer model 3YA-004-05) is mixed into liquid crystal 1, and the liquid crystal raw materials are heated and stirred to be evenly colored to form a blue-violet dye liquid crystal A; the blue-violet dye is a triazo blue-violet dye; the weight ratio of the blue-violet dye to the liquid crystal 1 is 2:98; the liquid crystal 1 is a nematic phase liquid crystal (liquid crystal manufacturer model 601).

[0058] An orange dye (liquid crystal manufacturer model 3YA-105-05) is mixed into liquid crystal 1, and heated and stirred to evenly color the liquid crystal raw material to form an orange dye liquid crystal B; the orange dye is a naphthyl-substituted anthraquinone orange dye; the weight ratio of the orange dye to the liquid crystal 1 is 3:97; the liquid crystal 1 is a nematic phase mixed crystal (liquid crystal manufacturer model 3YP-601).

[0059] A blue dye (liquid crystal manufacturer model 3YA-005-05) is mixed into liquid crystal 1, and heated and stirred to evenly color the liquid crystal raw material to form a blue dye liquid crystal C; the blue dye is a phenyl-substituted anthraquinone blue dye; the weight ratio of the blue dye to the liquid crystal 1 is 3:97; the liquid crystal 1 is a nematic phase mixed crystal (liquid crystal manufacturer model 601).

[0060] (2) The blue-violet liquid crystal A, orange liquid crystal B, and blue liquid crystal C are mixed evenly in a certain proportion to form a gray dye liquid crystal; the weight ratio of the blue-violet liquid crystal A, orange liquid crystal B, and blue liquid crystal C is 0.48:0.38:0.14.

[0061] (3) The gray liquid crystal and the polymer monomer composition are uniformly mixed to form an isotropic liquid crystal mixture at room temperature. The polymer monomer composition is a mixture of polymer monomers (methyl methacrylate and epoxy acrylic resin) and an initiator. The weight ratio of the gray liquid crystal to the polymer monomer composition is 48.5:51.5; the weight ratio of the methyl methacrylate to the epoxy acrylic resin is 7:3; the initiator is initiator TPO; and the weight ratio of the initiator to the polymer monomer is 0.3:99.7.

[0062] (4) mixing the liquid crystal mixture with glass beads, sandwiching the mixture between two transparent conductive films, and rolling to form a liquid crystal film; curing the liquid crystal film with ultraviolet light to form a gray polymer dispersed liquid crystal film;

[0063] The weight ratio of the glass beads to the liquid crystal mixture is 0.3:99.7; the transparent conductive film conductive layer can be indium tin oxide; the particle size of the glass beads is: 18 μm;

[0064] The UV curing time is 30 seconds, and the UV intensity is 15mw / cm 2 .

[0065] Example 4 Preparation of Gray Polymer Dispersed Liquid Crystal Film

[0066] The difference between Example 4 and Example 3 is that in step (2), liquid crystal 2 is further added; blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are uniformly mixed with liquid crystal 2 to form gray dye liquid crystal. The rest is the same as Example 3.

[0067] Step (2) is specifically as follows:

[0068] (2) The blue-violet liquid crystal A, orange liquid crystal B, blue liquid crystal C, and liquid crystal 2 are mixed uniformly in a certain proportion to form a gray dye liquid crystal; the weight ratio of the blue-violet liquid crystal A, orange liquid crystal B, blue liquid crystal C, and liquid crystal 2 is 0.38:0.31:0.11:0.2; the liquid crystal 2 is a nematic phase mixed crystal (liquid crystal manufacturer model 3YP-502).

[0069] The gray polymer dispersed liquid crystal film prepared by the methods of Examples 1 to 4 was cut into 100mm*150mm samples, two electrodes were set on the 100mm edge, and measured with Hangzhou Color Spectrum Haze Meter CS700 (C light source, ASTM standard), driven by an AC60V (50HZ) power supply, and tested its total light transmittance under power on and power off; the test results are shown in Table 1.

[0070] Table 1.

[0071]

[0072] It can be seen from the experiment in Table 1 that the gray polymer dispersed liquid crystal film prepared in Examples 1 and 3 has a large difference in total light transmittance; this means that: the blue-violet dye liquid crystal A, the orange dye liquid crystal B and the blue dye liquid crystal C are evenly mixed to form a gray dye liquid crystal; and then the gray dye liquid crystal is mixed with a polymer monomer to obtain a gray polymer dispersed liquid crystal film; it has a large difference in total light transmittance between the power-on state and the power-off state; so that when it changes between the transparent state and the frosted state, it has a significant change in color depth, which can meet high-demand application scenarios.

[0073] It can be seen from the experiment in Table 1 that the difference in total light transmittance of the gray polymer dispersed liquid crystal film prepared in Example 2 relative to that in Example 1, and the difference in total light transmittance of the gray polymer dispersed liquid crystal film prepared in Example 4 relative to that in Example 3, is further significantly increased. This means that: in step (2), liquid crystal 2 is added; the bluish-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are mixed evenly with liquid crystal 2 to form a gray dye liquid crystal; and then the gray dye liquid crystal is mixed with the polymer monomer to obtain a gray polymer dispersed liquid crystal film; the difference in total light transmittance between the power-on state and the power-off state is further increased.

Claims

1. A method for preparing a gray polymer dispersed liquid crystal film, characterized in that: Contains the following steps Steps: (1) Preparation of blue-violet dye liquid crystal A, orange dye liquid crystal B, and blue dye liquid crystal C; (2) Mix the blue-violet dye liquid crystal A, the orange dye liquid crystal B and the blue dye liquid crystal C evenly. Gray dye liquid crystals are formed; (3) uniformly mixing the gray dye liquid crystal and the polymer monomer composition to form an isotropic liquid crystal mixture at room temperature; (4) mixing the liquid crystal mixture with glass beads, sandwiching the mixture between two transparent conductive films, and rolling to form a liquid crystal film; Then, the liquid crystal film is cured to obtain the gray polymer dispersed liquid crystal film; The preparation method of the blue-violet dye liquid crystal A in step (1) is as follows: mixing the blue-violet dye into the liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form the blue-violet dye liquid crystal A; Wherein, the blue-violet dye is a triazo blue-violet dye; The weight ratio of the blue-violet dye to the liquid crystal 1 is 1:99 to 6:94; The preparation method of the orange dye liquid crystal B in step (1) is: mixing the orange dye into the liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form the orange dye liquid crystal B; Wherein, the orange dye is a naphthyl-substituted anthraquinone orange dye; The weight ratio of the orange dye to the liquid crystal 1 is 1:99 to 6:94; The preparation method of the blue dye liquid crystal C in step (1) is as follows: mixing the blue dye into the liquid crystal 1, heating and stirring to uniformly color the liquid crystal raw material to form the blue dye liquid crystal C; Wherein, the blue dye is a phenyl-substituted anthraquinone blue dye; The weight ratio of the blue dye to the liquid crystal 1 is 1:99 to 6:94; The liquid crystal 1 is a nematic phase mixed crystal; The weight ratio of the blue-violet dye liquid crystal A, the orange dye liquid crystal B, and the blue dye liquid crystal C in step (2) is (0.35-0.48): (0.35-0.48): (0.15-0.20).

2. The method for preparing a gray polymer dispersed liquid crystal film according to claim 1, characterized in that: In step (2), liquid crystal 2 is also added; blue-violet dye liquid crystal A, orange dye liquid crystal B and blue dye liquid crystal C are evenly mixed with liquid crystal 2 to form gray dye liquid crystal.

3. The method for preparing a gray polymer dispersed liquid crystal film according to claim 2, characterized in that: The weight ratio of the blue-violet dye liquid crystal A, the orange dye liquid crystal B, the blue dye liquid crystal C, and the liquid crystal 2 described in step (2) is (0.28-0.38): (0.28-0.38): (0.12-0.15): (0.18-0.22).

4. The method for preparing a gray polymer dispersed liquid crystal film according to claim 2, characterized in that: The liquid crystal 2 is a nematic mixed crystal.

5. A grey polymer dispersed liquid crystal film prepared by the preparation method according to any one of claims 1 to 4.

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