High-contrast dye PDLC (Polymer Dispersed Liquid Crystal) dimming film

Abstract

The invention relates to the technical field of dimming films, and particularly discloses a high-contrast dye PDLC dimming film, the dimming film comprises at least two PDLC layers and a double-sided conductive structure sandwiched between the at least two PDLC layers, and each of the at least two PDLC layers contains a composition comprising an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, an anthraquinone dichroic dye, and an anthraquinone dichroic dye or an anthraquinone dichroic dye. The liquid crystal composition comprises the following components in percentage by weight: 1-10wt% of a liquid crystal composition and the balance of a solvent, 5 to 40 wt% of a prepolymer; 5-30 wt% of a reactive diluent; 0.02 to 5 weight percent of a photoinitiator; 0-15 wt% of a chiral agent; and 0.1 to 0.9 wt% of a spacer. The problems that an existing PDLC light adjusting film is small in contrast ratio CR, large in on-state haze and light leakage in an off state, and the light shielding performance is dependent on the visual angle are solved.

Description

Technical Field

[0001] The present application relates to the field of dimming films, and in particular to a high-contrast dye PDLC dimming film. Background Art

[0002] The dimming film, specifically the liquid crystal dimming film, is a new type of electrochromic product. When the AC power is turned on / off, the liquid crystal molecules are arranged in an orderly / disordered manner, allowing the dimming film to switch between different haze or transmittance states.

[0003] PDLC dimming film is a mixture of liquid crystal / curable glue injected between two layers of transparent conductive film and cured, so that the liquid crystal is dispersed in the microcapsule structure formed by the cured glue. Due to the high content of glue, the overall adhesion of the PDLC dimming film is high and the packaging reliability is good. However, the glue is easily miscible with the liquid crystal, especially the compatibility of acrylic materials with liquid crystal is good at a suitable temperature, which causes the optical anisotropy of the liquid crystal to decrease, affecting the dimming range of the dimming film, and thus easily affecting the visual effect of the dimming film; and due to the poor refractive index matching between the liquid crystal and the glue, it is easy to cause the PDLC dimming film to have large haze in the open state, small viewing angle, small contrast (small CR), light leakage in the off state, and the shading performance is dependent on viewing angle. Therefore, a PDLC dimming film with high contrast is needed to achieve a better dimming effect. Summary of the invention

[0004] In order to solve the problems of low light transmittance contrast ratio CR of the current PDLC dimming film in the on-off state, light leakage in the off-state, and viewing angle dependence of the light shielding performance, the present application provides a PDLC dimming film and a method for preparing the dimming film.

[0005] The present invention adopts the following technical solution: A high-contrast dye PDLC dimming film includes at least two PDLC layers and a double-sided conductive structure sandwiched between the at least two PDLC layers. The double-sided conductive structure includes a first conductive layer, a second conductive layer and a substrate layer sandwiched between the first conductive layer and the second conductive layer.

[0006] Preferably, the dimming film having at least two PDLC layers is a dimming film having two PDLC layers or a dimming film having three PDLC layers.

[0007] The composition contained in each of the at least two PDLC layers includes an anthraquinone dichroic dye.

[0008] The invention is characterized in that: the composition contained in each of the at least two PDLC layers comprises: anthraquinone dichroic dye. The anthraquinone dichroic dye is 1 to 10 wt % calculated by weight, and the anthraquinone dichroic dye is two or more of the compounds represented by the following formula (I-1) to formula (I-8); Among them, preferably, A1, A2, A3, A4, A5, A6, A7, A8 and A9 are each independently selected from -H, -O-, -S-, -NH-, -COO-, -OCO-, -O(CH2CH2O)n-, and n is an integer from 1 to 20.

[0009] Among them, preferably H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H16 and H17 are each independently selected from the following structures: -H, cyclohexyl, aryl, naphthyl, optionally substituted heteroaryl, wherein the heteroaryl is selected from benzothiazolyl, benzoxazinyl, quinazolinyl, quinolyl, isoquinolyl, quinoxalinyl, pyridyl, pyrrolyl, oxazolyl, indolyl, pyridazinyl, pyrimidinyl, pyrazinyl.

[0010] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 are each independently selected from: -H, C1-C20 chain alkyl, -OCH3, -CF3, -OCF3, -C(CH3)3, -CN, -F, -Cl or -NCS; and may also be selected from: a structure in which one or more non-adjacent -CH2- in a C1-C20 chain alkyl is each independently replaced by -O-, -COO, -OCO-, -C=C-, CF=CF- or -C≡C-.

[0011] The anthraquinone dichroic dye shows good low-temperature solubility in the host liquid crystal material. In the present application, "good solubility" means a solubility of 0.2 to 3 wt % at -20°C. Preferably, the solubility is 0.3 to 2 wt %.

[0012] The anthraquinone dichroic dye has a dichroic ratio of ≥5.

[0013] It is worth mentioning that the above-mentioned dichroic dyes can be selected according to the color required by the actual product. In addition, some of the dichroic dyes used in the present invention can be purchased from the market, but they must meet the above-mentioned requirements.

[0014] The composition contained in each of the at least two PDLC layers further comprises the following components, calculated by weight percentage: 40-65wt% of liquid crystal composition; 5-40wt% of prepolymer; 5-30wt% of active diluent; 0.02-5wt% of photoinitiator; 0-15wt% of chiral agent; and 0.1-0.9wt% of spacer.

[0015] Preferably, the liquid crystal composition has a dielectric constant Δε (1KHZ 25°C) of 8 to 20, a clearing point > 90°C, a melting point < -30°C, an optical anisotropy of 0.18 to 0.28, and a rotational viscosity of < 120 cP at 20°C. The liquid crystal composition can be homemade or purchased commercially, but must meet the above requirements.

[0016] Preferably, the prepolymer is one or more of polyurethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate and polybutadiene acrylate.

[0017] Preferably, the active diluent is one or more of hydroxyethyl methacrylate, 1,4-butanediol diacrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl methacrylate, ethyl methacrylate, n-octyl methacrylate, trimethylolpropane triacrylate, isobornyl acrylate, isobornyl methacrylate, hydroxypropyl acrylate, and 2-carboxyethyl acrylate.

[0018] Preferably, the photoinitiator is a mixture of two or more of 1-hydroxycyclohexyl phenyl ketone, (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, α,α-dimethoxy-α-phenyl acetophenone, and 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0019] Preferably, the particle size of the spacer particles is 8 to 30 μm.

[0020] Preferably, the chiral agent is one or more of the compounds represented by the following formulas (Π-1) to (Π-7); Preferably, the PDLC dimming film with high contrast has a contrast ratio CR greater than or equal to 10 in both the powered and unpowered states.

[0021] Preferably, during the preparation of the dye PDLC dimming film, the PDLC dimming film is cured by ultraviolet light, the required energy is 3 to 30 mw / cm2, and the curing time is 2 to 10 minutes.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. By adopting the technical solution of at least two polymer disperse dye liquid crystal layers, the problem of off-state light leakage and light-shielding performance being dependent on viewing angle is solved; 2. The dimming layer contains dyes, which can further increase the switching contrast CR; 3. The polymer disperse dye liquid crystal layers are separated by a transparent conductive substrate layer having two conductive layers, which reduces the adhesive film layer and substrate layer used for direct bonding of a single-layer dimming film, and the dimming film structure is simpler. DETAILED DESCRIPTION

[0023] The present application is further described in detail below with reference to the embodiments. Example

[0024] Unless otherwise specified, the raw materials used in the embodiments of the present application are commercially available.

[0025] In the following examples, the anthraquinone dichroic dyes used are compounds shown in Table 1: Table 1 Anthraquinone dichroic dyes In the following examples, the names used, such as nematic liquid crystal E7 and C70, are liquid crystal compositions, which are purchased from the market by those skilled in the art.

[0026] In the following examples, the particle size of the spacer particles is 20 um.

[0027] In the following embodiments, the high-contrast dye PDLC dimming film involved may be a dimming film having a two-layer PDLC layer structure, or may be a dimming film having a three-layer PDLC layer structure.

[0028] The calculation method of contrast ratio is: contrast ratio CR = maximum transmittance of the dimming film in the on state / transmittance in the off state. Example

[0029] Example 1 The composition of the dye PDLC layer in this embodiment, the components and their corresponding weight percentages are shown in Table 2.

[0030] Table 2 PDLC layer composition Example 2 The composition of the dye PDLC layer in this embodiment, the components and their corresponding weight percentages are shown in Table 3.

[0031] Table 3 PDLC layer composition Example 3 The composition of the dye PDLC layer in this embodiment, the components and their corresponding weight percentages are shown in Table 4.

[0032] Table 4 PDLC layer composition Application Examples The dye PDLC material composition in the above-mentioned embodiments 1-3 is used to prepare a PDLC dimming film, and the preparation method thereof is as follows: after uniformly mixing a dichroic dye and a liquid crystal composition, a mixture A is obtained; after uniformly mixing an active diluent and a prepolymer, a mixture B is obtained; after uniformly mixing the mixture A and the mixture B, a mixture C is obtained; after adding a photoinitiator, spacer particles and a chiral agent to the mixture C, the mixture is stirred uniformly at room temperature (25° C.) in a dark environment to obtain a dye PDLC material composition; the obtained dye PDLC material composition is uniformly coated between three transparent substrates with a conductive coating (wherein the middle transparent substrate with a conductive coating layer is a double-sided conductive structure) by a coating and laminating machine, and a dimming film with a two-layer PDLC layer structure is obtained after UV curing and cutting; in addition, the obtained dye PDLC material composition is uniformly coated between four transparent substrates with a conductive coating (wherein the middle two transparent substrates with a conductive coating layer are a double-sided conductive structure) by a coating and laminating machine, and a dimming film with a two-layer PDLC layer structure is obtained after UV curing and cutting. The double-sided conductive structure includes a first conductive layer, a second conductive layer and a substrate layer sandwiched between the first conductive layer and the second conductive layer.

[0033] Performance test Test 1: Take the dimming films prepared in Examples 1-3 as test objects respectively, cut the PDLC dimming films into sheets of 100 mm × 100 mm respectively, and carry out the switching state haze test and the total light transmittance test after power-on according to the method specified in GB / T 2410-2008. The power-on voltage is 60 V. The test results are recorded in the following Tables 5 and 6.

[0034] Table 5 Test results of dimming film (containing two-layer PDLC layer structure) Table 6 Test results of dimming film (including three-layer PDLC structure) Test 2: Take the dye PDLC material compositions of Examples 1-3 as test objects respectively, and evenly apply the dye PDLC material compositions between three transparent substrates with conductive coatings through a coating press, wherein the middle transparent substrate with a conductive coating layer is a double-sided conductive structure, and after UV curing and cutting (cut into 100mm*100mm), a PDLC dimming film is obtained. The double-sided conductive structure includes a first conductive layer and a second conductive layer and a substrate layer sandwiched between the first conductive layer and the second conductive layer. Test the L*, a*, and b* values ​​of the sample.

[0035] The test results are recorded in Table VII.

[0036] Table VII L*, a*, b*, test values This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high contrast dye PDLC dimming film, characterized in that: The dimming film includes at least two PDLC layers and a double-sided conductive structure sandwiched between the at least two PDLC layers, wherein the composition contained in each of the at least two PDLC layers includes anthraquinone dichroic dye, so that a contrast ratio greater than or equal to 10 can be achieved.

2. According to the high contrast dye PDLC dimming film of claim 1, the anthraquinone dichroic dye is 1 to 10 wt% by weight, and the anthraquinone dichroic dye is two or more of the compounds represented by the following formulas (I-1) to (I-8); in, A1, A2, A3, A4, A5, A6, A7, A8 and A9 are each independently selected from -H, -O-, -S-, -NH-, -COO-, -OCO-, -O(CH2CH2O)-, -CH2O-, -CH=CH-, -CF=CF-, -CF2-CF2- or -(CH2)n-, where n is an integer from 1 to 20; wherein H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H16 and H17 are each independently selected from the following structures: -H, cyclohexyl, cyclohexenyl, cyclohexadienyl, aryl, naphthyl, cyclopentanyl, cyclopentenyl, cyclobutanyl, optionally substituted heteroaryl, wherein the heteroaryl is selected from benzothiazolyl, benzoxazinyl, quinazolinyl, quinolinyl, isoquinolinyl, quinoxalinyl, pyridyl, pyrrolyl, oxazolyl, indolyl, pyridazinyl, pyrimidinyl, pyrazinyl, 2-cyanopyridin-5-yl, furanyl, dibenzofuran-4-yl, benzofuranyl, dihydrothienodioxin, benzothienyl and dibenzothienyl; R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 are each independently selected from: -H, C1-C20 chain alkyl, C1-C20 chain alkyl halide, C1-C20 chain alkyl cyanide, -OCH3, -CF3, -OCF3, -C(CH3)3, -CN, -F, -Cl or -NCS; and may also be selected from: a structure in which one or more non-adjacent -CH2- in the C1-C20 chain alkyl is each independently replaced by -O-, -COO, -OCO-, -C=C-, CF=CF- or -C≡C-.

3. The high contrast dye PDLC dimming film according to claim 1, characterized in that: The double-sided conductive structure includes a first conductive layer, a second conductive layer and a substrate layer sandwiched between the first conductive layer and the second conductive layer.

4. The high contrast dye PDLC dimming film according to claim 2, characterized in that: The composition contained in each of the at least two PDLC layers further comprises the following components, calculated by weight percentage: 40-65wt% of liquid crystal composition; 5-40wt% of prepolymer; 5-30wt% of active diluent; 0.02-5wt% of photoinitiator; 0-15wt% of chiral agent; and 0.1-0.9wt% of spacer.

5. A high contrast dye PDLC dimming film according to claim 4, characterized in that the prepolymer is selected from one or more of water-based acrylates, epoxy acrylates, polyether acrylates, polysulfide ether acrylates, oily acrylates, vinyl ethers, acrylic prepolymers, polyester acrylates, polyethylene acrylates, polybutadiene acrylates and polyurethane acrylates.

6. A high contrast dye PDLC dimming film according to claim 4 or 5, characterized in that the active diluent is selected from one or more of trimethylolpropane triacrylate, hydroxybutyl vinyl ether, epoxy acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, hydroxypropyl acrylate, 2-carboxyethyl acrylate, isobornyl acrylate, isobornyl methacrylate, 1,4-butanediol diacrylate, n-octyl methacrylate, n-butyl methacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 4-hydroxybutyl acrylate, 1,6-hexanediol diacrylate, dicyclopentenyl acrylic acid, and N-acryloylmorpholine.

7. A high contrast dye PDLC dimming film according to claim 6, characterized in that the photoinitiator is selected from one or more of benzoin dimethyl ether, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 2,4,6 (trimethylbenzoyl) diphenylphosphine oxide, benzil derivatives, diphenylethanedione, 1-hydroxy-cyclohexylphenyl ketone, α,α-dimethoxy-α-phenylacetophenone, α,α-ethoxyacetophenone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, isopropylthioxanthone and bromothioxanthone.

8. A high contrast dye PDLC dimming film according to claim 4 or 5, characterized in that: The chiral agent is selected from one or more compounds represented by the following formula (Π-1) to formula (Π-7); 9. The high contrast dye PDLC dimming film according to claim 7, characterized in that: The chiral agent is selected from one or more compounds represented by the following formula (Π-1) to formula (Π-7); 10. A high contrast dye PDLC dimming film, characterized in that: Prepared according to any one of claims 1 to 9.

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