CN107085327A - A kind of electrically controlled dimming film based on liquid crystal and dichroic dye and its preparation method - Google Patents

Abstract

The present invention relates to a kind of electric-controlled light-regulating film based on liquid crystal and two tropism dyestuffs, including：First transparent indium tin oxide Plastic conductive film layer, composite film layer, the second transparent indium tin oxide Plastic conductive film layer；Wherein, the composite film layer includes liquid crystal molecule, two tropism dye molecules, macromolecule network, wherein, liquid crystal molecule and two tropism dye molecules are collectively forming the first composite regions, liquid crystal molecule, the second composite regions of two tropism dye molecules and macromolecule network formation, first composite regions are periodically alternately arranged with the second composite regions in composite film layer along incident light vertical direction.The electric-controlled light-regulating film of the present invention has the regulatable feature of transmitted light angular range.The electric-controlled light-regulating film is expected to be applied to display, by the opening and closing of electric field, display is switched between peep-proof and non-peep-proof state.

Description

A kind of electrically controlled dimming film based on liquid crystal and dichroic dye and its preparation method

technical field

The invention relates to the technical field of optical polarization, in particular to an electrically controlled dimming film based on liquid crystals and dichroic dyes and a preparation method thereof.

Background technique

Nowadays, electronic products have been integrated into people's life and work, and provide people with a lot of convenience. However, due to the large viewing angle of the liquid crystal display, when the information of electronic products is browsed by the user himself, it is very easy to Being peeped by the side, for some commercial and military secrets and personal privacy, people don't want to be peeped by the side.

The 3M company of the United States took the lead in developing the anti-peeping film with an ultra-fine louver (MICROLOVER) structure. Figure 1 is a schematic diagram of the principle of the anti-peeping film. As shown in the figure, the anti-peeping film includes in order from top to bottom: PET layer, adhesive layer, ultra-fine louver film layer, adhesive layer, PET layer, Adhesive layer, protective layer. Due to the ultra-fine louver film layer in the anti-spy film structure, when the anti-spy film is used for a display, the data displayed on the screen can be read exclusively by the user, and the viewing area is 60 degrees (± 30 degrees ), anyone outside the visible area can only see a dark picture, so as to achieve the purpose of protecting personal privacy and corporate business secrets. However, the anti-peeping film does not have the characteristic of switching between peep-proof and non-peep-proof states.

Contents of the invention

The purpose of the present invention is to overcome the defect that the existing anti-peeping film cannot be switched between the anti-peeping state and the non-peeping-proof state, so as to provide a dimming film whose anti-peeping state can be adjusted electrically.

In order to achieve the above object, the present invention provides an electronically controlled dimming film based on liquid crystal and dichroic dyes, comprising: a first transparent indium tin oxide plastic conductive film layer, a composite material film layer, a second transparent indium tin oxide plastic A conductive film layer; wherein, the composite material film layer includes liquid crystal molecules, dichroic dye molecules, and a polymer network, wherein the liquid crystal molecules and dichroic dye molecules together form the first composite material region, and the liquid crystal molecules, dichroic dye molecules The dye molecules and the polymer network jointly form the second composite material region, and the first composite material region and the second composite material region are periodically and alternately arranged in the composite material film layer along the vertical direction of the incident light.

In the above technical solution, the width range of any first composite material region is between 10-80 μm, and the width range of any second composite material region is between 10-80 μm.

In the above technical solution, the polymer network is formed by initiating the polymerization reaction of photopolymerizable monomers under the irradiation of ultraviolet light; wherein, the photopolymerizable monomers are liquid crystal monomers with monofunctional or multifunctional groups , or a mixture of multiple liquid crystal monomers, or a mixture of liquid crystal monomers and non-liquid crystal monomers; the content of the photopolymerizable monomer is 10-70wt% of the total content of the mixed liquid.

In the above technical solution, the dichroic dye is a positive dichroic black dye, or a mixture of a positive dichroic red dye, a positive dichroic blue dye and a positive dichroic yellow dye.

In the above technical solution, the liquid crystal is selected from nematic liquid crystal or cholesteric liquid crystal.

In the above technical scheme, the thickness of the composite material film layer is between 5-50 μm, and the thickness of the composite material film layer is determined by the size of the spacer particles; the spacer particles are selected from glass beads of a certain size, and the content is 0.1-1.0 wt% of the total content of the mixture of dichroic dye molecules, photopolymerizable monomers, liquid crystal molecules, photoinitiators and spacer particles.

In the above technical solution, when the electronically controlled dimming film is in the unpowered state, when the light is incident, the transmitted light is distributed in a wide angle range; when the electronically controlled dimming film is in the electrified state, When light is incident, the transmitted light is distributed over a narrow range of angles.

The present invention also provides a display, which uses the electronically controlled dimming film as a display screen, and the display can be switched between peep-proof and non-peep-proof states by turning on and off the electric field.

The present invention also provides a method for preparing an electronically controlled dimming film, including:

Step 1), preparing a well-oriented transparent indium tin oxide plastic conductive film layer;

Step 2), after uniformly mixing photopolymerizable monomers, liquid crystal molecules, dichroic dye molecules, photoinitiators, and spacer particles, sandwiching the mixed solution between two layers of transparent indium tin oxide plastic conductive film layers, and then making film;

Step 3), by using ultraviolet light to pass through the mask to irradiate the film, the ultraviolet light passing through the mask triggers a cross-linking reaction between the photopolymerizable monomer molecules to form a polymer network, liquid crystal molecules, and dichroic dye molecules. The material area, and the shielded part forms a composite material area of liquid crystal molecules and dichroic dye molecules, thereby forming a structure that is periodically and alternately arranged along the vertical direction of the incident light.

The advantages of the present invention are:

The electronically controlled dimming film of the present invention has excellent anti-peep performance, can be electrically controlled and adjusted, has a simple preparation method, and has a considerable effect of protecting personal privacy, and at the same time, the light transmittance will not be affected.

Description of drawings

Fig. 1 is the structural representation of the anti-peeping film with ultra-fine louver structure developed by 3M Company of the United States;

Fig. 2 is the light absorption schematic diagram of positive dichroic dye;

Fig. 3 (a) is the schematic diagram of the thin film that obtains when preparing electronically controlled dimming film in embodiment 1;

Fig. 3 (b) is the schematic diagram of the film shown in Fig. 3 (a) is irradiated by ultraviolet light through the mask in embodiment 1;

Figure 3(c) is a state diagram of the electronically controlled dimming film prepared in Example 1 without voltage applied;

Figure 3(d) is a state diagram of the electronically controlled dimming film prepared in Example 1 under voltage application;

Fig. 4 (a) is the schematic diagram of the thin film that obtains when preparing electrically controlled dimming film in embodiment 2;

Fig. 4 (b) is the schematic diagram of the film shown in Fig. 4 (a) illuminated by ultraviolet light through the mask in embodiment 2;

Figure 4(c) is a state diagram of the electronically controlled dimming film prepared in Example 2 without voltage applied;

Figure 4(d) is a state diagram of the electronically controlled dimming film prepared in Example 2 under voltage application;

Fig. 5 (a) is the polarizing microscope image of the electronically controlled dimming film prepared in Example 2 in an unpowered state;

Fig. 5 (b) is the polarized light micrograph of the electrically controlled dimming film prepared in embodiment 1 under the electrified state;

Fig. 6 (a) is the polarizing microscope image of the electronically controlled dimming film prepared in Example 2 in an unpowered state;

Fig. 6 (b) is the polarized light micrograph of the electronically controlled dimming film prepared in Example 2 in the electrified state;

Fig. 7 is the angle-light intensity distribution diagram of the electronically controlled dimming film prepared in Example 1 in the unpowered state (shown in line 1 in the figure) and the powered state (shown in line 2 in the figure);

Fig. 8 is an angle-light intensity distribution diagram of the electronically controlled dimming film prepared in Example 2 in the unpowered state (shown by line 1 in the figure) and the powered state (shown by line 2 in the figure).

detailed description

The present invention will be further described now in conjunction with accompanying drawing.

The electronically controlled dimming film of the present invention includes from top to bottom: a first transparent indium tin oxide (ITO) plastic conductive film layer, a composite material film layer, and a second transparent indium tin oxide plastic conductive film layer; wherein, the The composite film layer includes liquid crystal molecules, dichroic dye molecules, and a polymer network, wherein the liquid crystal molecules and the dichroic dye molecules jointly form the first composite material region, and the liquid crystal molecules, dichroic dye molecules, and the polymer network jointly form The second composite material region, the first composite material region and the second composite material region are periodically and alternately arranged in the composite material film layer along the vertical direction of the incident light. The width range of any first composite material region is between 10-80 μm, and the width range of any second composite material region is between 10-80 μm.

The polymer network is formed by initiating the polymerization reaction of photopolymerizable monomers under the condition of UV irradiation. The photopolymerizable monomer may be a monofunctional or polyfunctional liquid crystal monomer, or a mixture of multiple liquid crystal monomers, or a mixture of liquid crystal monomers and non-liquid crystal monomers. The content of the photopolymerizable monomer is generally 10-70wt% of the total content of the mixed solution. The photoinitiator is generally selected from one of Irgacure651, Irgacure184, Irgacure1173, Irgacure127, Irgacure2959, Irgacure784, and Irgacure2022. The photoinitiator content is 0.5-10wt% of the photopolymerizable monomer content.

The dichroic dye should adopt a positive dichroic black dye, or a mixture of a positive dichroic red dye, a positive dichroic blue dye, and a positive dichroic yellow dye, specifically, azo, Anthraquinones or other suitable dichroic dyes. Figure 2 is a schematic diagram of the light absorption of a positive dichroic dye. Line 1 in the figure represents the absorptivity when the positive dichroic dye is parallel to the light vector, and line 2 represents the absorbance when the positive dichroic dye is perpendicular to the light vector. Absorbance, Line 3 represents the absorbance of a positive dichroic dye under unpolarized light. It can be seen from the figure that the absorptivity of the positive dichroic dye when it is parallel to the light vector is significantly different from the absorptivity when the positive dichroic dye is perpendicular to the light vector.

The liquid crystal can be selected from nematic liquid crystal (NLC) or cholesteric liquid crystal (N*LC). NLC liquid crystals can be selected from positive commercial products or synthesized by themselves, such as one or a mixture of E7, E8, 5CB, SLC1717, SLC09535, SLC7011-100. N*LC can be prepared from commercial products, self-synthesis, or mixing chiral compounds into NLC. Chiral compounds can be selected from commercial products or synthesized by themselves. Common commercial products of chiral compounds include: S811, CB15, R1011, R5011, etc.

The thickness of the composite material film layer is between 5-50 μm, and the thickness of the composite material film layer can be controlled by controlling the size of the spacer particles. The spacer particles are glass beads of a certain size, and the content is 0.1-1.0wt% of the total content of the mixture of dichroic dye molecules, photopolymerizable monomers, liquid crystal molecules, photoinitiators and spacer particles.

In the following examples, NLC and N*LC will be respectively selected as liquid crystal molecular materials, and the process of how to prepare the electronically controlled dimming film of the present invention will be described.

Example 1

First, wash the PET substrate coated with ITO film with detergent and warm water, remove the particles, dust and impurities of the PET substrate, then wash it with acetone solution, and spin-coat a layer of PVA orientation on the PET substrate coated with ITO film. agent, cured at high temperature (110°C) for 2 hours, and carried out rubbing orientation. Next, after mixing the photopolymerizable liquid crystal monomer, DD molecules, NLC molecules, photoinitiators, and spacer particles evenly, the mixed solution is sandwiched between two layers of transparent ITO plastic conductive films, and then pressed into a film by pressing rollers. When it is shown in Figure 3(a). Then, as shown in Figure 3(b), by irradiating the film with ultraviolet (UV) light through a mask, the UV light passing through the mask triggers a cross-linking reaction between the photopolymerizable monomer molecules to form a photopolymerizable liquid crystal network , NLC, and DD composite material regions, and the shaded parts form NLC and DD composite material regions, thus forming a structure that is periodically and alternately arranged along the vertical direction of the incident light.

When no voltage is applied to the electronically controlled dimming film prepared by the above method, as shown in Figure 3(c), the NLC molecules are in a planar state, and according to the guest-host effect, the DD molecules are also in a planar orientation. At this time, the light absorption direction of DD molecules is perpendicular to the direction of incident light, so the absorption of incident light is relatively weak, and the transmitted light is distributed in a wide angle range from -α ₁ to +α ₁ . When an electric field is applied to the electronically controlled dimming film, as shown in Figure 3(d), the DD molecules in a part of the area anchored by the photopolymerizable liquid crystal network are anchored in a planar state, and the other area DD that is not anchored The molecules are vertically oriented along the direction of the electric field along with the NLC molecules, and the transmitted light can only be distributed in a narrow angle range of -α ₂ to +α ₂ .

Example 2

First, wash the PET substrate coated with ITO film with detergent and warm water, remove the particles, dust and impurities of the PET substrate, then wash it with acetone solution, and spin-coat a layer of PVA orientation on the PET substrate coated with ITO film. agent, cured at high temperature (110°C) for 2 hours, and then carried out rubbing orientation. Next, after mixing the photopolymerizable liquid crystal monomer, DD molecules, N*LC molecules, photoinitiators, and spacer particles evenly, the mixture is sandwiched between two layers of transparent ITO plastic conductive films, and then pressed into a film by pressing rollers , as shown in Figure 4(a). Then, as shown in Figure 4(b), by irradiating the film with ultraviolet (UV) light through a mask, the UV light passing through the mask triggers a cross-linking reaction between the molecules of the photopolymerizable liquid crystal monomer to form a photopolymerizable liquid crystal The network, N*LC, and DD composite material regions, and the shaded parts form N*LC, DD composite material regions, thus forming a structure that is periodically and alternately arranged along the vertical direction of the incident light.

When the electronically controlled dimming film prepared by the above method is not applied with voltage, as shown in Figure 4(c), the N*LC molecules are in a planar state, and according to the guest-host effect, the DD molecules are also in a planar orientation. At this time, the light absorption direction of the DD molecule is perpendicular to the direction of the incident light, showing weak absorption of the incident light, and the transmitted light is distributed in a wide angle range from -α ₃ to +α ₃ . When an electric field is applied to the electronically controlled dimming film, as shown in Figure 4(d), the DD molecules in a part of the region anchored by the photopolymerizable liquid crystal network are anchored in a planar state, and the DD molecules in the other part of the region are not anchored. The molecules are oriented along the direction of the electric field along with the N*LC to form a focal conic state, and the orientation of the DD molecules is random at this time. In the electrified state, the composite material film layer in the dimming film forms a structure similar to ultra-micro shutters, and the transmitted light can only be distributed within a narrow angle range of -α ₄ ~ +α ₄ .

Fig. 5 (a) is the polarizing microscope image of the electrically controlled dimming film prepared in Example 1 in the unpowered state, and Fig. 5 (b) is the electronically controlled dimming film prepared in Example 1 in Polarizing microscope image in the powered state. Fig. 6 (a) is the polarized light microscope image of the electrically controlled dimming film prepared in Example 2 in an unpowered state, and Fig. 6 (b) is a photo of the electrically controlled dimming film prepared in Example 2. Polarizing microscope image in the powered state. It can be seen from these polarized light microscopy images that the electronically controlled dimming film has a periodic stripe structure.

Fig. 7 is an angle-light intensity distribution diagram of the electronically controlled dimming film prepared in Example 1 in the unpowered state (shown by line 1 in the figure) and the powered state (shown by line 2 in the figure). Fig. 8 is an angle-light intensity distribution diagram of the electronically controlled dimming film prepared in Example 2 in the unpowered state (shown by line 1 in the figure) and the powered state (shown by line 2 in the figure). It can be seen from these two figures that the viewing angle of the electronically controlled dimming film prepared in Example 1 and Example 2 will change significantly under the state of being powered on or not, reaching the level between the anti-peeping state and the non-peeping-proof state. purpose of switching between.

The electronically controlled dimming film proposed by the present invention uses the guest-host effect properties of liquid crystals and dichroic dyes. Under the condition of applying an electric field, the user of the liquid crystal display can read from a frontal 60-degree viewing angle, that is, at any angle beyond 30 degrees left and right. The information on the screen cannot be seen clearly in the direction, protecting business secrets and personal privacy, making the use of the computer more free.

Based on the above-mentioned electronically controlled dimming film, the present invention also provides a display, which adopts the electronically controlled dimming film whose viewing angle can be adjusted as the display screen. Switch between states.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the present invention. within the scope of the claims.

Claims (9)

1. a kind of electric-controlled light-regulating film based on liquid crystal and two tropism dyestuffs, it is characterised in that including：First transparent indium tin oxide is moulded Expect conductive film layer, composite film layer, the second transparent indium tin oxide Plastic conductive film layer；Wherein, the composite film layer bag Liquid crystal molecule, two tropism dye molecules, macromolecule network are included, wherein, liquid crystal molecule and two tropism dye molecules are collectively forming One composite regions, liquid crystal molecule, two tropism dye molecules and macromolecule network are collectively forming the second composite regions, institute The first composite regions and the second composite regions are stated in composite film layer along incident light vertical direction periodicity It is alternately arranged.

2. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that any first The width range of composite regions between 10-80 μm, the width ranges of any second composite regions 10-80 μm it Between.

3. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that the high score Sub-network is formed under ultraviolet light by triggering photopolymerizable monomer to occur polymerisation；Wherein, the photopolymerizable Monomer is：The mixture of simple function group either multi-functional liquid crystal liquid crystal property monomer or plurality of liquid crystals monomer, or liquid crystal liquid crystal property The mixture of monomer and non-liquid crystal monomer；The photopolymerizable content of monomer is the 10-70wt% of mixed liquor total content.

4. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that described two to Property dyestuff use the tropism black dyes of positivity two, or the tropism orchil of positivity two, the tropism blue dyes of positivity two and positivity The mixture of two tropism welds.

5. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that the liquid crystal From nematic liquid crystal or cholesteric liquid crystal.

6. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that described compound The thickness of film layer is between 5-50 μm, and the thickness of the composite film layer is determined by the size of spacer particle；It is described Spacer particle selects the glass microballoon of certain size, and content is two tropism dye molecules, photopolymerizable monomer, liquid crystal molecule, light The 0.1-1.0wt% of initiator, the mixed liquor total content of spacer particle.

7. the electric-controlled light-regulating film according to claim 1 based on liquid crystal and two tropism dyestuffs, it is characterised in that described automatically controlled Light modulation film is in when being not added with electricity condition, and when light is incident, transmitted light is distributed in a wider angular range；When the electricity When controlled dimming film is in powering state, when light is incident, transmitted light is distributed in a narrower angular range.

8. a kind of display, it is characterised in that the display is using one of claim 1-7 electric-controlled light-regulating film as aobvious Display screen, by the opening and closing of electric field, display is switched between peep-proof and non-peep-proof state.

9. the preparation method of one of claim 1-7 electric-controlled light-regulating film, including：

Step 1), prepare the transparent indium tin oxide Plastic conductive film layer that has been orientated；

Step 2), photopolymerizable monomer, liquid crystal molecule, two tropism dye molecules, light trigger, spacer particle be well mixed Afterwards, mixed liquor is clipped in the middle of two layers of transparent indium tin oxide Plastic conductive film layer, film is then made；

Step 3), the film irradiated by using UV light permeability mask, through the ultraviolet light-initiated photopolymerizable list of mask Body is intermolecular to be crosslinked reaction and forms macromolecule network, liquid crystal molecule, two tropism dye molecule composite regions, and is hidden Cover part and form liquid crystal molecule, two tropism dye molecule composite regions, so as to be formed along the incident light vertical direction cycle The structure that property is alternately arranged.