CN111505857A - A PDLC dimming film and dimming glass - Google Patents

Abstract

A PDLC dimming film, the structure of which comprises a first base layer, a polymer-dispersed liquid crystal layer, and a second base layer sequentially stacked from top to bottom, wherein the polymer-dispersed liquid crystal layer includes liquid crystal and a polymer, and is characterized in that: At least one set of interdigital electrodes is provided on the side of the first base layer close to the polymer dispersed liquid crystal layer and/or the side of the second base layer close to the polymer dispersed liquid crystal layer. The distance between the liquid crystal molecules of the PDLC dimming film provided by the present invention is small, forming small gaps, so it has certain one-way visibility.

Description

A PDLC dimming film and dimming glass

Technical field:

The invention relates to the field of dimming films, in particular to a PDLC dimming film and a dimming glass.

Background technique:

Polymer dispersed liquid crystal (PDLC, Polymer dispersed liquid crystal) is an emerging optoelectronic material developed in the 1970s, and has been a research hotspot for researchers in recent decades. Polymer-dispersed liquid crystals have the advantages of simple preparation process, short response time, fast speed, and no need for polarizing devices. They have been gradually used in many electronic components such as light valves, gratings, light-transmitting projection screens, and dimming glass. The dimming glass is also called electronic curtain. Its working principle is as follows: when the power of the dimming glass is turned off, the liquid crystal molecules in the dimming glass show an irregular dispersion state. At this time, the light is scattered and the dimming glass is opaque. state; when the power of the dimming glass is turned on, the liquid crystal molecules in the dimming glass show a neat arrangement, and the light can penetrate freely at this time, and the dimming glass is in a light-transmitting state. Due to the dimming characteristics of dimming glass, it has been widely used in high-end places such as office buildings, medical institutions, and commercial exhibitions.

The existing PDLC dimming films are generally in the form of upper and lower double-sided electrodes, and an electric field exists between the surface electrodes to drive the liquid crystal molecules to rotate. The dimming mechanism of PDLC is through the scattering of light by the liquid crystal, so the haze of the PDLC dimming film is large, even if the haze can reach more than 80% in the dark state, and the measured light transmittance is still very high, and the sun shines in the When on the PDLC dimming glass, the state of white fog makes the human eye feel bad. When the PDLC dimming film is applied on automotive glass, due to the strong privacy of the interior space of the car, higher requirements are put forward for the dimming film. PDLC dimming film does not yet have one-way visibility. When the dimming glass is in a dark state, the inside of the car cannot see the outside, which affects the comfort of passengers. How to improve the one-way visual performance of PDLC and further improve the shading performance of dimming glass in dark state is the current research focus.

Invention content:

Aiming at the above technical problems existing in the prior art, the present invention provides a PDLC dimming film, which has a certain one-way visual performance, and a dimming glass, which has low transmittance in a dark state and good shading. sex.

The technical scheme adopted by the present invention is:

A PDLC dimming film, the structure of which comprises a first base layer, a polymer-dispersed liquid crystal layer, and a second base layer sequentially stacked from top to bottom, wherein the polymer-dispersed liquid crystal layer comprises liquid crystal and a polymer, and is characterized in that: At least one set of interdigital electrodes is provided on the side of the first base layer close to the polymer dispersed liquid crystal layer and/or the side of the second base layer close to the polymer dispersed liquid crystal layer. The electrodes can be prepared on only one side of the substrate, saving materials, and the direction of the deflection of the liquid crystal molecules is different from that of the conventional PDLC dimming film. The gap between the liquid crystal molecules is large, so that the PDLC dimming film has a certain one-way visibility. .

In a possible implementation manner, the interdigitated electrodes include first conductive strips and second conductive strips that are alternately arranged in parallel, and the first conductive strips and the second conductive strips are electrically connected to the first electrodes and the second electrodes, respectively. , the first electrode and the second electrode are electrically connected to an external power source.

In a possible implementation manner, the first conductive strip and the second conductive strip are elongated, with a width of less than 5 μm and a thickness of less than 10 μm. The size range of the conductive strip is obtained by weighing multiple factors such as construction difficulty and resistance value.

In a possible implementation manner, the distance between adjacent first conductive strips and second conductive strips is 2-30 μm. The distance between the conductive strips affects the force of the electric field between the conductive strips on the liquid crystal molecules under the same voltage.

In a possible implementation manner, the interdigital electrodes protrude from the upper surface of the first base layer or the second base layer. The interdigital electrode with the protruding surface has simple preparation steps, is easy to implement, and has a closer distance from the liquid crystal molecules and stronger electric field force.

In a possible implementation manner, the upper surface of the interdigital electrode is flush with the upper surface of the first base layer or the second base layer. Compared with the protruding surface, the interdigitated electrodes embedded in the base layer make the surface of the base layer still flat, and the interdigitated electrodes can be protected by the base layer and have stronger stability.

The present invention also provides a light-adjusting glass, comprising a laminated first light-transmitting plate and a second light-transmitting plate, characterized in that: any one of the above-mentioned light-transmitting plates is arranged between the first light-transmitting plate and the second light-transmitting plate. The PDLC dimming film described above. The PDLC dimming film with the above-mentioned interdigital electrodes is applied to the glass to obtain a dimming glass with certain one-way visibility.

In a possible implementation manner, the transmittance of at least one of the first light-transmitting plate and the second light-transmitting plate is less than 20%. The use of dark light-transmitting materials reduces the overall transmittance of the switchable glass.

In a possible implementation manner, a first adhesive layer is provided between the first light-transmitting plate and the PDLC light-adjusting film, and a second adhesive layer is provided between the second light-transmitting plate and the PDLC light-adjusting film. In the junction layer, the transmittance of at least one of the first adhesive layer and the second adhesive layer is less than 20%. The use of dark bonding materials reduces the overall transmittance of the dimming glass.

The present invention also provides a light-adjusting glass, comprising a laminated first light-transmitting plate and a second light-transmitting plate, characterized in that two layers of any of the above-mentioned ones are arranged between the first light-transmitting plate and the second light-transmitting plate. In the PDLC light-adjusting film, the electric field directions of the two layers of the PDLC light-adjusting film are perpendicular to each other. Two layers of PDLC dimming films with mutually perpendicular electric field directions are used, and the alignment directions of the liquid crystal molecules of the two layers of PDLC dimming films are also perpendicular to each other when energized. After the dimming film, it is absorbed to a large extent, and extinction occurs, which reduces the transmittance in the working state, that is, in the dark state.

The present invention has the following beneficial effects due to taking the above-mentioned technical scheme:

1. PDLC dimming film only needs to prepare electrodes on at least one base layer to realize the function of driving liquid crystal molecules to rotate. When only the interdigitated electrodes are arranged on the single-sided base layer, there is no danger of the upper and lower conductive layers that often occur in the conventional PDLC dimming film, and the thickness of the polymer dispersed liquid crystal layer can be reduced, so that the overall PDLC dimming film thickness is reduced. The deflection direction of the liquid crystal molecules under the action of the electric field is different from that of the conventional PDLC dimming film. Due to the large difference in the length of the long axis and the short axis of the liquid crystal, when the liquid crystal molecules are deflected by the electric field force after the above scheme is adopted, the difference between the liquid crystal molecules The gap is larger, so that the PDLC dimming film has a certain one-way visibility.

2. The dimming glass using the PDLC dimming film of the present invention has a certain one-way visibility. If two layers of PDLC dimming films with mutually perpendicular electric field directions are used, the liquid crystal of the two layers of PDLC dimming films will be energized. The molecular arrangement directions are also perpendicular to each other. Due to the dichroism of the liquid crystal, the incident light will be extinct after passing through the two layers of the PDLC dimming film with the liquid crystal molecules perpendicular to each other, thereby reducing the transmittance in the working state, that is, in the dark state.

3. Double-layer PDLC dimming film perpendicular to each other, the haze is small when the single-piece dimming film is energized, and the one-way visibility is good; when the two-piece dimming film is energized, the shading effect is better.

Description of drawings:

1 is a schematic diagram of the film layer structure of the PDLC light-adjusting film of the present invention;

Figure 2 is a schematic diagram of the film layer structure of another PDLC dimming film of the present invention;

Fig. 3 is the top view of the interdigitated electrode of the present invention;

4 is a schematic structural diagram of a dimming glass according to the present invention;

5 is a top view of another interdigital electrode of the present invention;

FIG. 6 is a schematic structural diagram of another dimming glass of the present invention.

Label description:

1. The first base layer, 2. The polymer dispersed liquid crystal layer, 3. The second base layer, 4. The interdigitated electrodes, 5. The first light-transmitting plate, 6. The first adhesive layer, 7. The second adhesive layer, 8, the second light-transmitting plate, 9, the third adhesive layer, 10, PDLC dimming film;

201, liquid crystal, 202, polymer;

401, the first conductive strip, 402, the second conductive strip, 403, the first electrode, 404, the second electrode.

Detailed ways:

In order to describe in detail the technical content, achieved objects and effects of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the implementations. example.

In the present invention, the orientations or positional relationships indicated by the terms "upper", "lower", etc. are all based on the orientations or positional relationships shown in the accompanying drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated device, element or component to have a specific orientation, and therefore should not be construed as a limitation of the present invention.

The present invention provides a PDLC dimming film, the structure of which includes a first base layer 1, a polymer-dispersed liquid crystal layer 2, and a second base layer 3 sequentially stacked from top to bottom, and the polymer-dispersed liquid crystal layer 2 includes a liquid crystal 201 and polymer 202, characterized in that the side of the first base layer 1 close to the polymer-dispersed liquid crystal layer 2 and/or the side of the second base layer 3 close to the polymer-dispersed liquid crystal layer 2 is provided with at least one set of forks Refer to electrode 4. The solution of the present invention can at least prepare the interdigital electrodes 4 on one side of the base layer, which saves electrode materials, and the deflection direction of the liquid crystal 201 is different from that of the conventional PDLC dimming film. The membrane 10 has some one-way visibility.

Preferably, the solution in which the single-sided base layer has the interdigitated electrodes 4 is taken as an example. In another embodiment, the first base layer 1 and the second base layer 3 may both be provided with the interdigitated electrodes 4 . As shown in FIG. 1 to FIG. 3 , the interdigitated electrode 4 includes a first conductive strip 401 and a second conductive strip 402 arranged in parallel in a staggered manner. Both leads are connected in parallel to the second electrode 404, and the first electrode 403 and the second electrode 404 are connected to both ends of the power supply, so they have opposite potentials. The first conductive strips 401 and the second conductive strips 402 are not necessarily limited to be parallel straight lines, as long as the distance between each of the two adjacent first conductive strips 401 and the second conductive strips 402 is the same to ensure dimming The overall dimming effect of the film can be uniform. The interdigitated electrodes 4 divide the molecules of the liquid crystal 201 into many elongated unit regions, and the liquid crystal 201 in each unit region is deflected by an alternating potential difference.

3 is a view of the side facing the substrate with the interdigitated electrodes 4, the liquid crystal 201 of the conventional PDLC dimming film is deflected by the potential difference between the upper and lower conductive layers of the polymer dispersed liquid crystal layer 2, and the space where the liquid crystal 201 is deflected The plane is perpendicular to the plane shown in FIG. 3 , and in the present invention, under the action of the interdigital electrodes 4 , the space plane where the liquid crystal 201 is deflected is the view plane of FIG. 3 . Usually, the long axis of the liquid crystal molecules is much longer than the short axis, and the ratio of the long axis and the short axis can even reach 10:1. The long axis of the liquid crystal 201 will be oriented along the direction of the electric field under the action of the electric field force. In the use scene of PDLC dimming film, the human eye usually observes the outside world through the dimming film on one side of the dimming film. When the liquid crystal 201 of the conventional PDLC dimming film is deflected, the human eye is facing the liquid crystal. The short axis of 201, because the short axis is small, the gap between the molecules of the liquid crystal 201 is large in the human field of vision at this time, and the light transmits well, making the two sides of the dimming film visible to each other. When the liquid crystal 201 of the light-adjusting film in the present invention is deflected, the human eye is facing the long axis of the liquid crystal 201. Since the long axis is long, the liquid crystal 201 molecules occupy a large proportion in the human visual field at this time, which makes the liquid crystal 201 in the visual field. The covering area becomes larger, the gap between the molecules of the liquid crystal 201 is smaller, and at this time, there is a certain one-way visibility. The meaning of one-way visibility is that on the weak side of the dimming film, the side with strong light can be seen well, while the side with strong light is difficult to observe the weak side, the principle and the glass curtain wall The one-way visual advertisement used is similar. The advertisement paper has many louver-like strips. The outside of the curtain wall is regarded as a normal advertisement, and the objects outside the window can be observed normally from a close distance from the inside of the curtain wall.

When using the scheme with the interdigital electrodes 4 on the single-sided base layer, since the liquid crystal 201 molecules are deflected on the space plane parallel to the conductive layer, and electrodes are only arranged on the single-sided base layer, there is no need to worry about the appearance of conventional PDLC dimming films. Because the thickness is too thin, the upper and lower conductive layers are short-circuited, so the thickness of the dimming film can be further reduced.

In another embodiment, the above-mentioned interdigitated electrodes 4 may be composed of a plurality of small interdigitated electrodes, and each interdigitated electrode 4 leads out two electrodes respectively, which are respectively connected to independent power control switches, thereby realizing sub-regional control.

The first base layer 1 and the second base layer 3 of the present invention are preferably PET films, and may also be PI and other common materials with similar uses. As shown in FIGS. 3-4 , the first conductive strips 401 and the second conductive strips 402 are arranged in a staggered manner, and a transparent conductive material such as ITO is usually used, and it can also be a common material with similar uses such as FTO. In one embodiment, the interdigitated electrodes 4 protrude from the surface of the PET film, and the required pattern of the interdigitated electrodes 4 is designed first, and is prepared on the surface of the PET film by a mature coating technology such as magnetron sputtering; In another embodiment, grooves can be made on the PET film according to the required pattern of the interdigital electrodes 4, and then transparent conductive materials are filled into the grooves to form conductive strips, and the upper surfaces of the conductive strips are flush with the PET film.

The sizes of the first conductive strips 401 and the second conductive strips 402 are determined according to the requirements and actual conditions. In the present invention, the widths of the first conductive strips 401 and the second conductive strips 402 are less than 5 μm, preferably 2 μm. The smaller the width, the denser the conductive strips. It is beneficial to the uniformity of the deflection of the liquid crystal 201 of the entire dimming film; another preferred width is 4 μm, and the width of the conductive strip is appropriately increased to reduce the resistance. The thickness of the first conductive strip 401 and the second conductive strip 402 is less than 10 μm, preferably 2 μm, the smaller the thickness, the less conductive material is required; the thickness can also be 5 μm, 6 μm, and the resistance can be reduced by appropriately increasing the thickness. The distance between the two adjacent first conductive strips 401 and the second conductive strips 402 directly affects the driving force for the liquid crystal 201 under the same voltage. In the present invention, the distance between the two adjacent first conductive strips 401 and the second conductive strips 402 It is 2-30 μm, preferably 5 μm, and can also be 6 μm, 10 μm, and 20 μm. If the spacing is too small, the preparation precision is high, and it is easy to short-circuit, and the power supply requires a higher driving voltage.

The present invention also provides a dimming glass, comprising a first light-transmitting plate 5 , a second light-transmitting plate 8 and the above-mentioned PDLC light-adjusting plate disposed between the first light-transmitting plate 5 and the second light-transmitting plate 8 The film 10, the dimming glass including the PDLC dimming film 10 can be a hollow structure or a sandwich structure. As shown in FIG. 4, a typical laminated glass structure is shown. In the embodiment of laminated glass, the PDLC dimming film 10 is connected to the first light-transmitting plate 5 and the second light-transmitting plate 5 through the first adhesive layer 6 and the second adhesive layer 7, respectively. The light-transmitting plate 8 is combined, and the interlayer process is a very mature process in the glass industry. The PDLC dimming film 10 has a certain one-way visibility, and the dimming glass using the PDLC dimming film 10 also has a certain one-way visibility. Visibility, usually the side of the glass facing the outside or the outside of the car is the brighter side, while the side close to the interior or the inside of the car is darker, so the inner side can be seen in one direction to the outer side.

The first light-transmitting plate 5 and the second light-transmitting plate 8 are preferably conventional glass, which can be a single piece of ordinary glass or tempered glass, laminated glass, or plexiglass. Materials have applicability in the present invention, and the material change of the light-transmitting plate will not fundamentally affect the implementation of the solution of the present invention. In one embodiment, at least one of the first light-transmitting plate 5 and the second light-transmitting plate 8 is made of dark light-transmitting material, and the transmittance of the light-transmitting plate using dark light-transmitting material is less than 20%, and the color is usually Black or gray, thereby reducing the overall transmittance of the dimming glass. In another embodiment, at least one of the first adhesive layer 6 and the second adhesive layer 7 selects a dark-colored adhesive material, and the transmittance of the dark-colored adhesive material used is less than 20%. in black or grey. In application scenarios such as car sunroofs, high transmittance is not required, but the transmittance requirements for dimming glass in the dark state are low enough.

The present invention also provides a light-adjustable glass, comprising a laminated first light-transmitting plate 5 and a second light-transmitting plate 8 and two layers of PDLC tunable glass disposed between the first light-transmitting plate 5 and the second light-transmitting plate 8 For the optical film 10, at this time, for the sandwich structure, a third adhesive layer 9 needs to be added. As shown in FIGS. 5 to 6 , the directions of the interdigital electrodes 4 on the two layers of PDLC dimming films 10 are perpendicular to each other, so that the directions of the electric fields on the two layers of PDLC dimming films 10 are perpendicular to each other. When the optical films 10 are in the working state by applying alternating driving voltages, the deflection directions of the liquid crystals 201 on the two layers of PDLC dimming films 10 are also perpendicular to each other, that is, the short axes of the liquid crystals 201 are perpendicular to each other. Due to the optical rotation and dichroism of the liquid crystal 201, after a beam of natural light passes through the molecules of the liquid crystal 201, part of the polarized light whose polarization direction is the same as the short axis direction of the liquid crystal 201 will be weakened. After the PDLC dimming film 20, a considerable part of natural light is absorbed. The effect of the two-layer dimming film is similar to that of two polarizers perpendicular to each other, absorbing polarized light in two vertical directions, thus making the overall transmittance of the dimming glass lower.

All the bonding layers mentioned in the present invention are made of organic materials commonly used in the laminated glass process, such as PVB, EVA, POB, etc. The application of bonding materials in the glass industry is very mature and will not be repeated here.

In addition to the above-mentioned dimming glass with a sandwich structure, a PDLC dimming film can also be applied to the glass with a hollow structure to form a dimming glass with a hollow structure. The process of insulating glass is also very mature. It is easier to compound the dimming film into the insulating glass, and the preparation process is simple. However, due to the thickness and curvature of the insulating glass, its application, especially in ordinary cars, is compared. In the occasions where the thickness is less sensitive, such as architectural glass curtain wall, hollow is a better product structure.

The above description is only to provide a better embodiment of the present invention, not to limit the present invention, and the present invention is not limited to the above examples. Additions or substitutions also belong to the protection scope of the present invention.

Claims (10)

1. A PDLC light-adjusting film, its structure comprises the first base layer (1) layered sequentially from top to bottom, a polymer-dispersed liquid crystal layer (2), a second base layer (3), the polymer-dispersed liquid crystal layer The layer (2) comprises a liquid crystal (201) and a polymer (202), characterized in that the first base layer (1) is close to the side of the polymer dispersed liquid crystal layer (2) and/or the second base layer ( 3) At least one group of interdigital electrodes (4) is provided on the side close to the polymer dispersed liquid crystal layer (2). 2. The PDLC dimming film according to claim 1, wherein the interdigital electrode (4) comprises a first conductive strip (401) and a second conductive strip (402) which are alternately arranged in parallel, the first conductive strip (402) The strip (401) and the second conductive strip (402) are respectively electrically connected to the first electrode (403) and the second electrode (404), and the first electrode (403) and the second electrode (404) are electrically connected to an external power source. 3 . The PDLC dimming film according to claim 2 , wherein the first conductive strips ( 401 ) and the second conductive strips ( 402 ) are elongated, with a width of less than 5 μm and a thickness of less than 10 μm. 4 . 4 . The PDLC light-adjusting film according to claim 2 , wherein the distance between the adjacent first conductive strips ( 401 ) and the second conductive strips ( 402 ) is 2-30 μm. 5 . 5 . The PDLC light-adjusting film according to claim 1 , wherein the interdigital electrodes ( 4 ) protrude from the upper surface of the first base layer ( 1 ) or the second base layer ( 3 ). 6 . 6. A PDLC dimming film according to claim 1, wherein the upper surface of the interdigital electrode (4) is aligned with the upper surface of the first base layer (1) or the second base layer (3) flat. 7. A light-adjusting glass, comprising a laminated first light-transmitting plate (5) and a second light-transmitting plate (8), characterized in that: the first light-transmitting plate (5) and the second light-transmitting plate ( 8) The PDLC light-adjusting film (10) according to any one of claims 1-6 is arranged between them. 8. The dimming glass according to claim 7, wherein the transmittance of at least one (parallel light) of the first light-transmitting plate (5) and the second light-transmitting plate (8) is less than 20%. 9. The dimming glass according to claim 7, characterized in that a first adhesive layer (6) is provided between the first light-transmitting plate (5) and the PDLC dimming film (10), A second adhesive layer (7) is arranged between the second light-transmitting plate (8) and the PDLC light-adjusting film (10), the first adhesive layer (6), the second adhesive layer (7) The transmittance of at least one layer is less than 20%. 10. A light-adjusting glass, comprising a laminated first light-transmitting plate (5) and a second light-transmitting plate (8), characterized in that: the first light-transmitting plate (5) and the second light-transmitting plate ( 8) Two layers of the PDLC light-adjusting film (10) according to any one of claims 1-6 are disposed between, and the electric field directions of the two layers of the PDLC light-adjusting film (10) are perpendicular to each other.

Images