Light valve dimming film, preparation method and application thereof

Abstract

The application provides a light valve dimming film and a preparation method and application thereof. The dimming film comprises a suspension and a base polymer, the suspension comprises an acrylic polymer and dimming particles, and the base polymer is selected from an epoxy resin; the mass ratio of the dimming particles, the acrylic polymer and the epoxy resin is (0.1-5):100:200-350. The dimming film uses the epoxy resin as the base polymer, the acrylic polymer in the suspension can be dispersed into the epoxy resin in the form of small droplets with micron-level size, a phase separation state is formed, and the particle sedimentation problem is improved; meanwhile, the two polymers have similar refractive indexes, so that the prepared dimming film has good transparency. In addition, the size of the droplets in the dimming film is more conducive to the flipping of the dimming particles, so that the light transmittance is improved, and the performance of an SPD device is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid light valve, and particularly relates to a light valve dimming film and a preparation method and application thereof. BACKGROUND

[0002] The intelligent window technology can control the solar radiation flux through the glass window pane, thereby reducing glare and improving the energy efficiency of air conditioning in residential and office buildings. There are different types of intelligent window technology, such as electrochromic, polymer dispersed liquid crystal, gel-glass dispersed liquid crystal and dipole particle suspension (SPD) (also known as suspended particle device). Among these solutions, the SPD device can well control the solar radiation flux. The SPD is composed of a structure similar to a sandwich, which is covered on both sides by ITO glass or a conductive film, and the light dimming particles in the form of elongated rods are suspended in the liquid light valve. When an external electric field is applied, the particles polarize and rotate in the liquid light valve under the torque of the applied electric field, and align with the applied electric field, realizing the change of the light transmittance of the device. The performance of the liquid light valve directly affects the performance of the SPD device.

[0003] The liquid light valve is composed of two incompatible polymers, in which polymer a is mixed with light dimming particles to form a suspension, and the suspension is dispersed in the form of fine droplets in polymer b (base polymer), forming a phase separation state. By adding a photoinitiator to polymer b, polymer b can be cured by ultraviolet light, so as to realize the preparation of the light valve into a film form between the two ITO glasses.

[0004] However, the polymer b currently located in the middle of the ITO glass is mainly a siloxane polymer, which is relatively high in price, difficult to prepare and low in yield. In addition, the existing polymer b has the problem of low adhesion coefficient with the ITO glass, which leads to poor contact between the polymer and the glass and easy separation, thereby resulting in poor stability of the device. Moreover, the size of the droplets in the phase separation system needs to be further reduced. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a light valve dimming film and a preparation method and application thereof. The droplet size in the dimming film is moderate, which is conducive to the flipping of the light dimming particles, thereby improving the light transmittance and having good transparency.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows.

[0007] A light valve dimming film, the dimming film comprising a suspension and a base polymer, the suspension comprising an acrylic polymer and light dimming particles, and the base polymer being selected from an epoxy resin; the mass ratio of the light dimming particles, the acrylic polymer and the epoxy resin being (0.1-5):100:200-350.

[0008] In some embodiments, the mass ratio of the light-adjusting particles, the acrylic polymer and the epoxy resin is (0.1-5): 100: 250-350. Preferably, the mass ratio of the light-adjusting particles, the acrylic polymer and the epoxy resin is (0.1-5): 100: 300-350.

[0009] In some embodiments, the viscosity of the acrylic polymer at 25°C is 50 mPa.s-1000 mPa.s; preferably, the viscosity of the acrylic polymer at 25°C is 100 mPa.s-800 mPa.s; more preferably, the viscosity of the acrylic polymer at 25°C is 200 mPa.s-500 mPa.s.

[0010] In some preferred embodiments, the acrylic polymer is a polymethacrylate compound; more preferably, the polymethacrylate compound is at least one selected from polybutyl methacrylate, polyoctyl methacrylate, polylauryl methacrylate, polyhexadecyl methacrylate.

[0011] In some embodiments, the light-adjusting particles are selected from calcium polyiodide pyrazine dicarboxylate light polarizing particles, iodine quinine sulfate light polarizing particles.

[0012] In some embodiments, the epoxy resin is selected from one or more of bisphenol A epoxy resin, tetra-bromobisphenol A type epoxy resin, multifunctional epoxy resin, phenolic epoxy resin.

[0013] In some embodiments, the light-adjusting particles further comprise trioctyl trimellitate, and the mass ratio of the trioctyl trimellitate to the acrylic polymer is 1:0.5-3. The trioctyl trimellitate can adjust the size of the liquid droplets formed by the dispersion of the acrylic polymer in the suspension, further improving the light transmittance.

[0014] In some embodiments, the thickness of the light-adjusting film is 20 μm-300 μm; preferably, the thickness of the light-adjusting film is 80 μm-120 μm.

[0015] The present application also provides a preparation method of the light-adjusting film as described above, comprising the following steps: (1) dissolving light-adjusting particles using an ester solvent to obtain a light-adjusting particle solution; (2) uniformly mixing the light-adjusting particle solution with an acrylic polymer, and ultrasonically treating to obtain a mixed solution; (3) removing the volatile solvent from the mixed solution by rotary evaporation to obtain a suspension; (4) uniformly mixing the suspension with an epoxy resin and deaerating; (5) coating and curing the deaerated product to obtain the light-adjusting film.

[0016] In some embodiments, a tricaprylyl trimellitate is also added in step (2). In some embodiments, the ester solvent in step (1) is selected from one or more of ethyl acetate, n-propyl acetate, butyl acetate, isoamyl acetate.

[0017] The present application also provides the use of the light modulating film as described above or the light modulating film prepared by the method as described above in the preparation of a light valve.

[0018] The present application also provides a thin film light valve, which comprises two layers of transparent electrodes and a light modulating film as described above or a light modulating film prepared by the method as described above between the two layers of transparent electrodes.

[0019] In some embodiments, the transparent electrode is selected from one or more of ITO conductive glass, ITO conductive film, nano-Ag line conductive film, nano-Cu line conductive film, PEDOT conductive film, graphene conductive film, carbon nanotube conductive film.

[0020] The present application provides a light valve light modulating film, which uses epoxy resin as the base polymer, and the acrylic polymer in the suspension can be dispersed into the epoxy resin in the form of small droplets of micron size, forming a phase separation state, improving the particle sedimentation problem; at the same time, the two polymers have similar refractive indexes, so that the prepared light modulating film has good transparency. In addition, the size of the droplets in the light modulating film is more conducive to the flipping of the light modulating particles, thereby improving the light transmittance and enhancing the performance of the SPD device.

[0021] The present application uses epoxy resin instead of siloxane polymer as the base polymer of the light valve, which can effectively reduce the cost and improve the yield while improving the performance of the SPD device. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The electron microscope image of the thin film light valve prepared in Example 1.

[0023] Figure 2 The light transmittance results of the thin film light valve prepared in Example 1.

[0024] Figure 3 The light transmittance results of the thin film light valve prepared in Example 2.

[0025] Figure 4 The light transmittance results of the thin film light valve prepared in Example 3.

[0026] Figure 5 The light transmittance results of the thin film light valve prepared in Comparative Example 1.

[0027] Figure 6 The electron microscope image of the thin film light valve prepared in Example 4.

[0028] Figure 7 The electron microscope image of the thin film type light valve prepared for Example 5 was obtained.

[0029] Figure 8 The electron microscope image of the thin film type light valve prepared for Comparative Example 2 was obtained. DETAILED DESCRIPTION

[0030] The experimental methods not specified in the following examples of the present application are generally carried out according to the conventional conditions, or according to the conditions suggested by the manufacturers. The various common chemical reagents used in the examples are commercially available products.

[0031] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] The terms "comprising" and "having" and any variations thereof used in the present application are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of steps or modules is not limited to the listed steps or modules, but can optionally further include additional steps or modules not listed, or can optionally further include other steps inherent to such processes, methods, articles, or apparatus.

[0033] In the present application, "a plurality of" means two or more. "And / or", which describes the association relationship of the associated objects, means that there can be three relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0034] The following will be described in conjunction with specific examples.

[0035] In the present application, the acrylic polymer can be obtained by direct purchase or prepared according to conventional technical means in the art.

[0036] In the present application, the light adjusting particles can be obtained by purchase or synthesized by using conventional technical means in the art. For example, the calcium polyiodide pyrazine dicarboxylic acid light polarization particles are prepared by the following method:

[0037] 1. Warm 20 g of isoamyl acetate solution to 65℃, add 0.76 g (3 mmol) of iodine and 0.56 g (1.5 mmol) of calcium iodide tetrahydrate, and after stirring for 30 min, cool to 45℃.

[0038] 2. Add excess 0.4g (2mmol) of anhydrous 2,5-pyrazinedicarboxylic acid, 0.2ml of water and 0.4ml of methanol, and stir for 3h.

[0039] 3. Collect the reacted mixture into a centrifuge tube and sonicate for 2h.

[0040] 4. Wash the product with isopentyl acetate and centrifuge to remove excess iodine and impurities. Repeat the centrifugation process 3-4 times until the supernatant solution is gradually clear and the grey-brown precipitate gradually turns into a blue-grey precipitate to obtain the final sample.

[0041] In the following examples, the epoxy resin is an indigo epoxy resin-crystal drop glue.

[0042] Example 1

[0043] This example provides a thin film light valve prepared by the following method:

[0044] 1. Mix 2g of a 1% mass fraction of dimming particles (calcium pyrazinedicarboxylate polyiodide light polarization particles) in isopentyl acetate with 2g of polymethyl butyl acrylate (viscosity 200mPa.s);

[0045] 2. After stirring the mixed solution with a magnetic stirrer for 10min, sonicate for 10min using an ultrasonic wave; then use a rotary evaporation device to evaporate the solvent for 1h to obtain a suspension;

[0046] 3. Mix 6g of epoxy resin A component with 0.6g of epoxy resin B component to obtain an epoxy resin;

[0047] 4. Mechanically mix the suspension with the mixed epoxy resin, stir thoroughly for 30min, and then quickly place it in a vacuum oven to degas to obtain a mixture;

[0048] 5. Use a 100μm wire rod to coat the mixture into a 100μm thick film, and use a UV lamp to irradiate for 5min for curing;

[0049] 6. Use a 5μm wire rod to coat a 5μm light curing glue (Lutian 9307) on one side of the ITO glass electrode, cover both sides of the film, and then perform UV curing again to prepare a thin film light valve, as shown in Figure 1 .

[0050] Example 2

[0051] This example provides a thin film light valve prepared by the following method:

[0052] 1. Take 2 g of 2% mass fraction of light-adjusting particles (calcium polyiodide light polarization particles of pyrazine dicarboxylic acid) in isoamyl acetate solution and mix with 2 g of polyoctyl methacrylate (viscosity of 250 mPa.s);

[0053] 2. After stirring the mixed solution with a magnetic stirrer for 10 min, use ultrasonic waves for 10 min; then use a rotary evaporation device to evaporate the solvent for 1 h to obtain a suspension;

[0054] 3. Take 6 g of epoxy resin A component and 0.6 g of epoxy resin B component and mix them evenly to obtain an epoxy resin;

[0055] 4. Mechanically mix the suspension with the mixed epoxy resin, stir thoroughly for 30 min, and then quickly put it into a vacuum oven to degas, obtaining a mixture;

[0056] 5. Use a 100 μm wire bar to coat the mixture into a 100 μm thick film, use a UV lamp to irradiate for 5 min for curing;

[0057] 6. Use a 5 μm wire bar to coat a 5 μm light-curing adhesive (Lantian 9307) on one side of the ITO glass electrode, cover both sides of the film, and then perform UV curing again to prepare a thin film type light valve.

[0058] Example 3

[0059] This example provides a thin film type light valve, which is prepared by the following method:

[0060] 1. Take 2 g of 3% mass fraction of light-adjusting particles (calcium polyiodide light polarization particles of pyrazine dicarboxylic acid) in isoamyl acetate solution and mix with 2 g of polyoctyl methacrylate (viscosity of 500 mPa.s);

[0061] 2. After stirring the mixed solution with a magnetic stirrer for 10 min, use ultrasonic waves for 10 min; then use a rotary evaporation device to evaporate the solvent for 1 h to obtain a suspension;

[0062] 3. Take 6 g of epoxy resin A component and 0.6 g of epoxy resin B component and mix them evenly to obtain an epoxy resin;

[0063] 4. Mechanically mix the suspension with the mixed epoxy resin, stir thoroughly for 30 min, and then quickly put it into a vacuum oven to degas, obtaining a mixture;

[0064] 5. Use a 100 μm wire bar to coat the mixture into a 100 μm thick film, use a UV lamp to irradiate for 5 min for curing;

[0065] 6. Using a 5 μm wire bar, coat one side of the ITO glass electrode with a 5 μm layer of the light-cured glue (Lantian 9307), cover both sides of the film, and then perform ultraviolet light curing again to prepare the film-type light valve.

[0066] Comparative Example 1

[0067] This example provides a film-type light valve prepared by the following method:

[0068] 1. Mix 2 g of a 1% by mass solution of light-adjusting particles (calcium polyiodide of pyrazine dicarboxylic acid light polarization particles) in isoamyl acetate with 2 g of polymethyl butyl acrylate (viscosity 200 mPa.s);

[0069] 2. After stirring the mixed solution using a magnetic stirrer for 10 min, perform ultrasonic treatment using an ultrasonic device for 10 min, and then perform rotary evaporation using a rotary evaporation device for 1 h to evaporate the solvent and obtain a suspension;

[0070] 3. Take 6.6 g of polyphenylmethylsiloxane;

[0071] 4. Mechanically mix the suspension with the polyphenylmethylsiloxane, stir thoroughly for 30 min, and then quickly place in a vacuum oven to remove bubbles;

[0072] 5. Using a 100 μm wire bar, coat the mixture into a 100 μm thick film, and perform curing using an ultraviolet lamp for 5 min;

[0073] 6. Using a 5 μm wire bar, coat one side of the ITO glass electrode with a 5 μm layer of the light-cured glue (Lantian 9307), cover both sides of the film, and then perform ultraviolet light curing again to prepare the film-type light valve.

[0074] Using an ultraviolet-visible spectrophotometer, detect the light transmittance of the film-type light valves prepared in the above examples and comparative example.

[0075] Figures 2 to 4 The light transmittance results of the film-type light valves prepared in Examples 1-3, respectively, Figure 5 The light transmittance results of the film-type light valve of Comparative Example 1. Compared with Comparative Example 1, the light-adjusting film prepared in the present application (Examples 1-3) has higher transparency, and the film-type light valve has higher light transmittance.

[0076] Example 4

[0077] This example provides a film-type light valve without light-adjusting particles, for illustrating the size of liquid droplets, prepared by the following method:

[0078] 1. Take 2 g of polymethyl butyl acrylate with a viscosity of 200 mPa.s;

[0079] 2. Take 6 g of epoxy resin A component and 0.6 g of epoxy resin B component and mix them evenly to obtain an epoxy resin;

[0080] 3. Mechanically mix the polybutyl methacrylate with the mixed epoxy resin, fully stir for 30 min, and then quickly put it into a vacuum oven for debubbling to obtain a mixture;

[0081] 4. Use a 100 μm wire bar to coat the mixture into a 100 μm thick film, use a UV lamp to irradiate for 5 min for curing;

[0082] 5. Use a 5 μm wire bar to coat a 5 μm light-curing adhesive (Lantian 9307) on one side of an ITO glass electrode, cover both sides of the film, and then perform UV curing again to prepare a film type light valve, and the liquid drops in the film type light valve are as shown in Figure 6 .

[0083] Example 5

[0084] This example provides a film type light valve without light adjusting particles, for illustrating the size of liquid drops, which is prepared by the following method:

[0085] 1. Take 2 g of polybutyl methacrylate (viscosity of 200 mPa.s) and 2 g of trioctyl trimellitate to form a mixed solution;

[0086] 2. After stirring the mixed solution with a magnetic stirrer for 10 min, use ultrasonic wave to ultrasonic for 10 min to obtain a suspension;

[0087] 3. Take 6 g of epoxy resin A component and 0.6 g of epoxy resin B component and mix them evenly to obtain an epoxy resin;

[0088] 4. Mechanically mix the suspension with the mixed epoxy resin, fully stir for 30 min, and then quickly put it into a vacuum oven for debubbling to obtain a mixture;

[0089] 5. Use a 100 μm wire bar to coat the mixture into a 100 μm thick film, use a UV lamp to irradiate for 5 min for curing;

[0090] 6. Use a 5 μm wire bar to coat a 5 μm light-curing adhesive (Lantian 9307) on one side of an ITO glass electrode, cover both sides of the film, and then perform UV curing again to prepare a film type light valve, and the liquid drops in the film type light valve are as shown in Figure 7 .

[0091] Comparative Example 2

[0092] This comparative example provides a film type light valve without light adjusting particles, for illustrating the size of liquid drops, which is prepared by the following method:

[0093] 1. Take 2g of polybutyl methacrylate, viscosity 200mPa.s;

[0094] 2. Take 6.6g of polyphenylmethylsiloxane;

[0095] 3. Mechanically mix the polybutyl methacrylate and the polyphenylmethylsiloxane, fully stir for 30min, then quickly put into a vacuum oven to degas, to obtain a mixture;

[0096] 4. Use a 100μm wire bar to coat the mixture into a 100μm thick film, use a UV lamp to irradiate for 5min, to perform curing;

[0097] 5. Use a 5μm wire bar to coat a 5μm light curing adhesive (Lantian 9307) on one side of an ITO glass electrode, cover both sides of the film, then perform UV curing again, to prepare a film type light valve, the liquid drops in the film type light valve are as shown in Figure 8 .

[0098] Use an electron microscope to measure the size of the liquid drops in the film type light valve prepared in the above examples and the comparative examples.

[0099] The results are shown in Table 2:

[0100] Table 2

[0101] Group Mean droplet diameter Example 4 19 μm Example 5 13 μm Comparative Example 2 23 μm

[0102] The above results show that, compared with Comparative Example 2, the suspension in the film type light valve prepared in the present application (Examples 4-5) is dispersed in the base polymer in smaller liquid drops, can form more liquid bubbles, and makes the phase separation phenomenon more obvious, thereby improving the light adjusting performance of the device; at the same time, the number of particles in the liquid drops can be reduced, thereby avoiding particle agglomeration.

[0103] Compared with Example 4, the addition of trioctyl trimellitate in Example 5 can further reduce the size of the liquid drops, and better avoid particle agglomeration.

[0104] In summary, the light adjusting film of the present application uses an epoxy resin as the base polymer, and the acrylic polymer in the suspension can be dispersed in the epoxy resin in smaller micron-sized liquid drops, which can effectively improve the transparency of the film and the light transmittance of the device.

[0105] The technical features of the above examples can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above examples are described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0106] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A light valve dimming film characterized by, The light-adjustable film comprises a suspension and a base polymer, the suspension comprises an acrylic polymer and light-adjustable particles, the base polymer is selected from epoxy resin; the mass ratio of the light-adjustable particles, the acrylic polymer and the epoxy resin is (0.1-5):100:200-350; The viscosity of the acrylic polymer at 25℃ is 50 mPa.s-1000 mPa.s; and / or, The light-adjustable particles are selected from at least one of the following: pyrazine dicarboxylic acid calcium polyiodide light polarization particles, iodine sulfuric acid quinine light polarization particles; and / or, The epoxy resin is selected from one or more of the following: bisphenol A epoxy resin, multifunctional epoxy resin; The acrylic polymer is selected from at least one of the following: polybutyl methacrylate, polyoctyl methacrylate, polylauryl methacrylate, polyhexadecyl methacrylate; Trioxin is further included, and the mass ratio of the trioxin to the acrylic polymer is 1:0.5-3.

2. The light modulating thin film of claim 1, wherein, The mass ratio of the light-adjustable particles, the acrylic polymer and the epoxy resin is (0.1-5):100:250-350.

3. The light modulating thin film of claim 1, wherein, The thickness of the light-adjustable film is 20 μm-300 μm.

4. The light modulating thin film of claim 1, wherein, The epoxy resin is selected from one or more of the following: tetra-bromine bisphenol A type epoxy resin, phenolic epoxy resin.

5. The method for preparing the dimming film according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: (1) dissolving light-adjustable particles using ester solvent to obtain a light-adjustable particle solution; (2) mixing the light-adjustable particle solution with an acrylic polymer uniformly, and ultrasonic treatment to obtain a mixed solution; (3) removing the volatile solvent from the mixed solution by rotary evaporation to obtain a suspension; (4) mixing the suspension with an epoxy resin uniformly and defoaming; (5) coating and curing the defoamed product to obtain the light-adjustable film.

6. The production method according to claim 5, wherein Trioxin is further added in step (2); and / or, The ester solvent in step (1) is selected from one or more of the following: ethyl acetate, n-propyl acetate, butyl acetate, isoamyl acetate.

7. Use of the light-adjustable film according to any one of claims 1-4 or the light-adjustable film prepared by the method according to any one of claims 5-6 in the preparation of a light valve.

8. A thin film type light valve, characterized by comprising: The film-type light valve comprises two layers of transparent electrodes and the light-adjustable film according to any one of claims 1-4 or the light-adjustable film prepared by the method according to any one of claims 5-6 between the two layers of transparent electrodes.

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