CN116675949A - Light valve dimming film and preparation method and application thereof - Google Patents

Abstract

The invention provides a light valve dimming film, a preparation method and application thereof, wherein the dimming film comprises a suspension and a matrix polymer, the suspension comprises an acrylic polymer and dimming particles, and the matrix polymer is selected from epoxy resin; the mass ratio of the dimming particles to the acrylic polymer to the epoxy resin is (0.1-5): 100: 200-350. The dimming film takes epoxy resin as a matrix polymer, and the acrylic polymer in suspension can be dispersed into the epoxy resin in the form of tiny liquid drops with smaller micron-sized, so that a phase separation state is formed, and the problem of particle sedimentation is solved; meanwhile, the refractive indexes of the two polymers are similar, so that the prepared dimming film has good transparency. In addition, the size of the liquid drop in the dimming film is more beneficial to overturning of dimming particles, so that the light transmittance is improved, and the performance of the SPD device is improved.

Description

A light valve dimming film and its preparation method and application

technical field

The invention belongs to the technical field of liquid light valves, and in particular relates to a light valve dimming film and its preparation method and application.

Background technique

Smart window technology can control the flux of solar radiation through glass panes, thereby reducing glare and improving the energy efficiency of air conditioning in residential and office buildings. There are different types of smart window technologies such as electrochromic, polymer dispersed liquid crystal, gel-glass dispersed liquid crystal and dipole particle suspension (SPD) (also called suspended particle device). From these solutions, SPD devices can well control the solar radiation flux. SPD is composed of a structure similar to a sandwich. Both sides are covered with ITO glass or conductive film, and slender rod-shaped dimming particles 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 applied by the electric field, and align with the applied electric field, realizing the change of light transmittance of the device. The performance of the liquid light valve directly affects the performance of the SPD device.

The liquid light valve is composed of two incompatible polymers, in which polymer a is mixed with dimming particles to form a suspension, which is dispersed in polymer b (matrix polymer) in the form of fine droplets to form a state of separation. Adding a photoinitiator to the polymer b can cure the polymer b by ultraviolet light, so that the light valve can be prepared in the form of a thin film, which is placed between two layers of ITO glass.

However, the current polymer b located in the middle of ITO glass is mainly siloxane polymer, which is expensive, difficult to prepare, and low in yield. In addition, the existing polymer b has the problem of low adhesion coefficient with ITO glass, resulting in poor contact and easy separation of the polymer and glass, resulting in poor device stability. Moreover, the droplet size in the phase separation system needs to be further reduced.

Contents of the invention

Based on this, the object of the present invention is to provide a light valve dimming film and its preparation method and application. The droplet size in the dimming film is moderate, which is beneficial to the turning over of the dimming particles, thereby improving the light transmittance, and Has good transparency.

In order to achieve the above object, the present invention adopts the following technical solutions.

A light valve dimming film, the dimming film comprises a suspension and a matrix polymer, the suspension comprises an acrylic polymer and dimming particles, and the matrix polymer is selected from epoxy resin; the dimming The mass ratio of particles, acrylic polymer and epoxy resin is (0.1-5):100:200-350.

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

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

In some preferred embodiments, the acrylic polymer is a polymethacrylate compound; more preferably, the polymethacrylate compound is selected from polybutyl methacrylate, polyoctyl methacrylate At least one of ester, polylauryl methacrylate, polyhexadecyl methacrylate.

In some embodiments, the light-adjusting particles are selected from pyrazine dicarboxylic acid polycalcium iodide light polarizing particles and quinine iodosulfate light polarizing particles.

In some embodiments, the epoxy resin is selected from one or more of bisphenol A epoxy resin, tetrabromobisphenol A epoxy resin, multifunctional epoxy resin, and novolak epoxy resin.

In some embodiments, the light-adjusting particles further include trioctyl trimellitate, and the mass ratio of the trioctyl trimellitate to the acrylic polymer is 1:0.5-3. Trioctyl trimellitate can adjust the size of the droplets formed by the dispersion of the acrylic polymer in the suspension, and further improve the light transmittance.

In some embodiments, the thickness of the dimming film is 20 μm˜300 μm; preferably, the thickness of the dimming film is 80 μm˜120 μm.

The present invention also provides a method for preparing the dimming film as described above, comprising the following steps: (1) using an ester solvent to dissolve the dimming particles to obtain a dimming particle solution; (2) mixing the dimming particle solution with acrylic acid The polymer-like mixture is uniformly mixed, and ultrasonic treatment is performed to obtain a mixed solution; (3) the mixed solution is rotary evaporated to remove volatile solvents to obtain a suspension; (4) the suspension is mixed evenly with epoxy resin and defoamed (5) coating and curing the defoamed product to obtain the dimming film.

In some embodiments, trioctyl 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, and isoamyl acetate.

The present invention also provides the application of the above-mentioned light-adjusting film or the light-adjusting film prepared by the above-mentioned method in the preparation of light valves.

The present invention also provides a film-type light valve, which includes two layers of transparent electrodes and the above-mentioned dimming film or the dimming film prepared by the above-mentioned method between the two layers of transparent electrodes. film.

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

The invention provides a light valve dimming film. The dimming film uses epoxy resin as a matrix polymer, and the acrylic polymer in the suspension can be dispersed into the epoxy resin with smaller micron-sized droplets. , form a phase separation state, and improve the problem of particle sedimentation; at the same time, the refractive index of the two polymers is similar, so that the prepared dimming film has good transparency. In addition, the size of the liquid droplets in the light-adjusting film is more conducive to the flipping of the light-adjusting particles, thereby increasing the light transmittance and improving the performance of the SPD device.

In the invention, the epoxy resin is used as the matrix polymer of the light valve instead of the siloxane polymer, which can effectively reduce the cost and increase the yield while improving the performance of the SPD device.

Description of drawings

FIG. 1 is an electron micrograph of the thin-film light valve prepared in Example 1.

FIG. 2 shows the light transmittance results of the film-type light valve prepared in Example 1. FIG.

FIG. 3 shows the light transmittance results of the thin-film light valve prepared in Example 2. FIG.

FIG. 4 shows the light transmittance results of the thin film light valve prepared in Example 3. FIG.

FIG. 5 shows the light transmittance results of the film-type light valve prepared in Comparative Example 1. FIG.

FIG. 6 is an electron micrograph of the thin-film light valve prepared in Example 4. FIG.

FIG. 7 is an electron micrograph of the thin-film light valve prepared in Example 5. FIG.

FIG. 8 is an electron microscope image of the thin-film light valve prepared in Comparative Example 2. FIG.

Detailed ways

The experimental methods without specific conditions indicated in the following examples of the present invention are usually in accordance with conventional conditions, or in accordance with the conditions suggested by the manufacturer. Various commonly used chemical reagents used in the examples are all commercially available products.

Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by one of ordinary skill in the technical field of the present invention. Terms used in the description of the present invention are only for the purpose of describing specific embodiments, and are not used to limit the present invention.

The terms "including" and "having" and any variations thereof in the present invention are intended to cover a non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps is not limited to the listed steps or modules, but optionally also includes steps that are not listed, or optionally also includes for these processes, Other steps inherent in a method, product, or apparatus.

The "plurality" mentioned in the present invention means two or more. "And/or" describes the association relationship of associated objects, indicating that there may be three types of relationships, for example, A and/or B may indicate: A exists alone, A and B exist simultaneously, and B exists independently. The character "/" generally indicates that the contextual objects are an "or" relationship.

The following will be described in conjunction with specific embodiments.

In the present invention, the acrylic polymer can be purchased directly, or can be prepared according to conventional technical means in the field.

In the present invention, the light-adjusting particles can be purchased or synthesized by means of conventional techniques in the art. For example, the pyrazine dicarboxylic acid polyiodide calcium polarizing particles are prepared by the following method:

1. Warm up 20g of isoamyl acetate solution to 65°C, add 0.76g (3mmol) of iodine element and 0.56g (1.5mmol) of calcium iodide tetrahydrate, stir for 30min and cool down to 45°C.

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.

3. Collect the reacted mixture into a centrifuge tube for sonication, and sonicate the mixed solution for 2 hours.

4. Wash and centrifuge the product with isoamyl acetate to remove excess iodine and impurities therein. Repeat the centrifugation process 3-4 times until the supernatant solution after centrifugation is gradually clarified, and the beige precipitate gradually turns into a blue-gray precipitate, and the final sample is obtained.

In the following examples, the epoxy resin is indigo epoxy resin-crystal glue.

Example 1

This embodiment provides a thin-film light valve, which is prepared by the following method:

1. Mix 2g of isoamyl acetate solution of 1% dimming particles (calcium pyrazine dicarboxylate polyiodide light polarizing particles) with a mass fraction of 2g and mix with 2g of polybutylmethacrylate (viscosity: 200mPa.s);

2. Stir the mixed solution with a magnetic stirrer for 10 minutes, then use an ultrasonic wave for 10 minutes; then use a rotary evaporator for 1 hour to evaporate the solvent to dryness to obtain a suspension;

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

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

5. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and irradiate it with a UV lamp for 5 minutes to cure;

6. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm photocurable adhesive (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a thin film light valve, as shown in Figure 1.

Example 2

This embodiment provides a thin-film light valve, which is prepared by the following method:

1. Take 2g of isoamyl acetate solution of 2% dimming particles (calcium pyrazine dicarboxylate polyiodide light polarizing particles) with a mass fraction of 2% and mix with 2g of polyoctyl methacrylate (viscosity is 250mPa.s);

2. Stir the mixed solution with a magnetic stirrer for 10 minutes, then use an ultrasonic wave for 10 minutes; then use a rotary evaporator for 1 hour to evaporate the solvent to dryness to obtain a suspension;

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

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

5. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and irradiate it with a UV lamp for 5 minutes to cure;

6. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm photocurable adhesive (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a thin film light valve.

Example 3

This embodiment provides a thin-film light valve, which is prepared by the following method:

1. Take 2g of isoamyl acetate solution with a mass fraction of 3% light-adjusting particles (calcium pyrazine dicarboxylate polyiodide light polarizing particles) and mix it with 2g of polylauryl methacrylate (viscosity is 500mPa.s);

2. Stir the mixed solution with a magnetic stirrer for 10 minutes, then use an ultrasonic wave for 10 minutes; then use a rotary evaporator for 1 hour to evaporate the solvent to dryness to obtain a suspension;

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

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

5. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and irradiate it with a UV lamp for 5 minutes to cure;

6. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm photocurable adhesive (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a thin film light valve.

Comparative example 1

This embodiment provides a thin-film light valve, which is prepared by the following method:

1. Mix 2g of isoamyl acetate solution of 1% dimming particles (calcium pyrazine dicarboxylate polyiodide light polarizing particles) with a mass fraction of 2g and mix with 2g of polybutylmethacrylate (viscosity: 200mPa.s);

2. Stir the mixed solution with a magnetic stirrer for 10 minutes, then use an ultrasonic wave for 10 minutes; then use a rotary evaporator for 1 hour to evaporate the solvent to dryness to obtain a suspension;

3. Take 6.6g polyphenylmethylsiloxane;

4. Mechanically mix the suspension with polyphenylmethylsiloxane, fully stir for 30 minutes, and then quickly put it into a vacuum oven for degassing;

5. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and irradiate it with a UV lamp for 5 minutes to cure;

6. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm photocurable adhesive (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a thin film light valve.

The light transmittance of the film-type light valves prepared in the above examples and comparative examples was detected by using an ultraviolet-visible spectrophotometer.

2 to 4 are respectively the light transmittance results of the thin film light valves prepared in Examples 1 to 3, and FIG. 5 is the light transmittance results of the thin film light valves in Comparative Example 1. Compared with Comparative Example 1, the light-adjusting film prepared by the present invention (Examples 1-3) has higher transparency, and the film-type light valve has higher light transmittance.

Example 4

This example provides a film-type light valve without dimming particles, which is used to illustrate the droplet size, which is prepared by the following method:

1. Take 2g of polybutylmethacrylate with a viscosity of 200mPa.s;

2. Mix 6g of epoxy resin component A with 0.6g of epoxy resin component B to obtain epoxy resin;

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

4. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and use a UV lamp for 5 minutes to cure;

5. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm light-curing glue (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a film-type light valve, and the liquid in the film-type light valve The drop is shown in Figure 6.

Example 5

This example provides a film-type light valve without dimming particles, which is used to illustrate the droplet size, which is prepared by the following method:

1. Take 2g polybutylmethacrylate (viscosity is 200mPa.s) and mix with 2g trioctyl trimellitate to form a mixed solution;

2. Stir the mixed solution with a magnetic stirrer for 10 minutes, and then use an ultrasonic wave for 10 minutes to obtain a suspension;

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

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

5. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and irradiate it with a UV lamp for 5 minutes to cure;

6. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm photocurable adhesive (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a film-type light valve, and the liquid in the film-type light valve The drop is shown in Figure 7.

Comparative example 2

This comparative example provides a film-type light valve without dimming particles to illustrate the droplet size, which is prepared by the following method:

1. Take 2g of polybutylmethacrylate with a viscosity of 200mPa.s;

2. Take 6.6g polyphenylmethylsiloxane;

3. Mechanically mix polybutyl methacrylate and polyphenylmethylsiloxane, stir thoroughly for 30 minutes, and then quickly put it into a vacuum oven for degassing to obtain a mixture;

4. Use a 100 μm wire rod to coat the mixture into a 100 μm thick film, and use a UV lamp for 5 minutes to cure;

5. Use a 5 μm wire rod to coat one side of the ITO glass electrode with a layer of 5 μm light-curing glue (Lantian 9307), cover both sides of the film, and then perform UV curing again to prepare a film-type light valve, and the liquid in the film-type light valve The drop is shown in Figure 8.

The size of the liquid droplets in the thin-film light valves prepared in the above examples and comparative examples was measured using an electron microscope.

The results are shown in Table 2:

Table 2

group droplet mean diameter Example 4 19μm Example 5 13μm Comparative example 2 23μm

The above results show that, compared with Comparative Example 2, the suspension in the film-type light valve prepared by the present invention (Examples 4-5) is dispersed in the matrix polymer with finer droplets, and more liquid bubbles can be formed. The phenomenon of phase separation is more obvious, thereby improving the dimming performance of the device; at the same time, the number of particles in the droplet can be reduced, thereby avoiding particle agglomeration.

Compared with Example 4, the addition of trioctyl trimellitate in Example 5 can further reduce the droplet size and better avoid particle agglomeration.

In summary, the light-adjusting film of the present invention uses epoxy resin as the matrix polymer, and the acrylic polymer in the suspension can be dispersed into the epoxy resin with smaller micron-sized droplets, which can effectively improve the film’s performance. Transparency and light transmittance of the device.

The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of concise description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A light valve dimming film, the dimming film comprising a suspension comprising an acrylic polymer and dimming particles and a matrix polymer selected from the group consisting of epoxy resins; the mass ratio of the dimming particles to the acrylic polymer to the epoxy resin is (0.1-5): 100: 200-350.

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

3. The light-adjusting film according to claim 1, wherein the viscosity of the acrylic polymer at 25 ℃ is 50mpa.s to 1000mpa.s; and/or the number of the groups of groups,

the dimming particles are at least one selected from pyrazine dicarboxylic acid multi-calcium iodide light polarizing particles and quinine iodized sulfate light polarizing particles; and/or the number of the groups of groups,

the epoxy resin is selected from one or more of bisphenol A epoxy resin, tetrabromobisphenol A epoxy resin, multifunctional epoxy resin and phenolic epoxy resin.

4. A light modulating film according to claim 3, wherein said acrylic polymer is a polymethacrylate; preferably, the polymethacrylate compound is at least one selected from polybutyl methacrylate, octyl methacrylate, lauryl methacrylate and cetyl methacrylate.

5. The light-adjusting film according to claim 1, further comprising trioctyl trimellitate, wherein the mass ratio of trioctyl trimellitate to the acrylic polymer is 1:0.5 to 3.

6. The light-adjusting film according to claim 1, wherein the thickness of the light-adjusting film is 20 μm to 300 μm; preferably, the thickness of the light modulation film is 80 μm to 120 μm.

7. The method for producing a light-adjusting film according to any one of claims 1 to 6, comprising the steps of: (1) Using an ester solvent to dissolve dimming particles to obtain a dimming particle solution; (2) Uniformly mixing the dimming particle solution with an acrylic polymer, and carrying out ultrasonic treatment to obtain a mixed solution; (3) Spin-evaporating the mixed solution to remove volatile solvent to obtain suspension; (4) Uniformly mixing the suspension with epoxy resin and then defoaming; (5) And coating and solidifying the defoamed product to obtain the dimming film.

8. The process according to claim 7, wherein trioctyl trimellitate is further added in step (2); and/or the number of the groups of groups,

the ester solvent in the step (1) is one or more selected from ethyl acetate, n-propyl acetate, butyl acetate and isoamyl acetate.

9. Use of a dimming film according to any one of claims 1 to 6 or a dimming film prepared by a method according to any one of claims 7 to 8 in the preparation of a light valve.

10. A thin film light valve comprising two transparent electrodes and a dimming thin film according to any one of claims 1 to 6 or a dimming thin film prepared by the method according to any one of claims 7 to 8 interposed between the two transparent electrodes.