High-dielectric flame-retardant film and quick-response electronic paper

Abstract

A preparation method of the high-dielectric flame-retardant film comprises the following steps: dissolving polyvinyl alcohol in water to obtain a polyvinyl alcohol aqueous solution, adding a phosphine / silicon amphiphilic compound into the polyvinyl alcohol aqueous solution, then adding boric acid, uniformly mixing, smearing on a substrate, and drying to obtain the high-dielectric flame-retardant film. A preparation method of the quick response electronic paper comprises the following steps: constructing the metal template with the microcup structure by using a laser etching processing method, placing the metal template on the high-dielectric flame-retardant film, and performing imprinting by using nano-imprinting equipment to manufacture the microcup structure. OP-KH and PVA are compounded to prepare the film, so that the flame retardant property is enhanced. OP-KH with amphipathicity is added, so that the dielectric constant of the thin film is greatly improved, the hydrophobicity of the surface is improved, the adhesion between electrophoretic particles and a microcup interface is weakened by a high hydrophobic interface, the desorption time of the particles on the surface is shortened, and the response time is greatly prolonged when the thin film is applied to a microcup type electronic paper base film.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic paper, and in particular to a high-dielectric flame-retardant film and a fast-response electronic paper. Background Art

[0002] Electronic paper is a general term for reflective paper-like displays that combine the reading comfort of traditional paper with the versatility of modern electronic devices. The response speed and refresh rate of electronic paper are important indicators for evaluating the display quality of electronic paper. Fast response and high refresh rate mean that electronic paper can quickly update the displayed content, reduce delays when images change, and provide users with a smoother visual experience.

[0003] Electrophoretic electronic paper is a rapidly developing electronic paper type. According to the difference of the microcavity that carries the electrophoretic particles, it is divided into microcapsule type and microcup type electrophoretic display. Microcup type electronic paper is to print a microcup with polymer material, then pour ink into the microcup, seal the cup mouth, and connect the upper and lower surfaces of the microcup to the electrode. The display is realized by driving the electrophoretic particles in the microcup to move between the electrodes through voltage. The voltage applied between the two electrodes is distributed to the encapsulation layer and the other to the electrophoretic fluid. Since the polymer is not conductive, the voltage share distributed to both ends of the electrophoretic fluid is low, resulting in a decrease in the particle movement rate and an increase in the device response time. Experiments have shown that increasing the dielectric constant of the polymer layer is one of the ways to increase the particle response speed.

[0004] The refresh rate of electronic paper depends on the movement speed of electronic ink particles and the desorption speed of ink particles from the electrode surface. If the ink particles are firmly bound to the surface and difficult to separate from the electrode surface, the refresh rate will be delayed. In addition, polymer as a microcup substrate is a flammable material, and the encapsulated electronic ink mainly contains isoalkanes, which are also flammable. Summary of the invention

[0005] The purpose of the present invention is to provide a high dielectric constant flame retardant film in view of the defects of the prior art. The preparation method is as follows: polyvinyl alcohol is dissolved in water to obtain a polyvinyl alcohol aqueous solution, a phosphine / silicon amphiphilic compound is added to the polyvinyl alcohol aqueous solution, and then boric acid is added. After mixing, the mixture is applied to a substrate, and the high dielectric constant flame retardant film is obtained after drying.

[0006] Furthermore, the preparation method of the phosphine / silicon amphiphilic compound is as follows: 2-methyl-1,2-oxophosphine-5-one 2-oxide and KH550 are mixed in a molar ratio of 1:1, and the reaction equation is as follows:

[0007] Chemicals

[0008] Furthermore, the reaction condition is 100° C. for 2 hours.

[0009] Furthermore, the amount of polyvinyl alcohol is 90wt% to 70wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, the amount of phosphine / silicon amphiphilic compound is 10wt% to 30wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, and the amount of boric acid is 3wt% of the mass of polyvinyl alcohol.

[0010] Furthermore, the amount of polyvinyl alcohol is 90wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, the amount of phosphine / silicon amphiphilic compound is 30wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, and the amount of boric acid is 3wt% of the mass of polyvinyl alcohol.

[0011] Furthermore, the thickness of the high-dielectric flame-retardant film is 40-50 um.

[0012] A fast-response electronic paper made of a high-dielectric flame-retardant film, the preparation method of which is as follows: a metal template with a microcup structure is constructed by a laser etching method, the metal template is placed on the high-dielectric flame-retardant film, and nanoimprinting equipment is used for imprinting to produce a microcup structure.

[0013] Furthermore, the microcup is a regular hexagon, the side length of the regular hexagon is 10-100 μm, the gap between two regular hexagons is 1-50 μm, and the height of the microcup is 10-50 μm. Furthermore, the gap between two regular hexagons is 3 μm, and the height of the regular hexagon of the template is 30 μm.

[0014] Furthermore, the embossing step is: embossing at a temperature of 80-95°C for 20-30 minutes under a pressure of 200 psi, then reducing the temperature to 30°C at a rate of 2°C / min, maintaining for 10 minutes, and removing the pressure to obtain a high dielectric constant flame retardant film with a microcup structure. The beneficial effects of the present invention are:

[0015] 1. The film is made of OP-KH and PVA, which enhances the flame retardant performance and makes the composition have excellent flame retardant performance. The vertical burning grade of the tested composition reaches UL-94V-0.

[0016] 2. The addition of amphiphilic OP-KH greatly improves the dielectric constant of the film and increases the hydrophobicity of the surface. The highly hydrophobic interface can weaken the adhesion between the inorganic electrophoretic particles and the microcup interface, reduce the desorption time of the particles on the surface, and greatly improve the response time when it is applied to the microcup type electronic paper base film. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a morphology diagram of the electronic paper microcup of the present invention;

[0018] Figure 2 This is the test result of the electronic paper response time of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below by way of examples and comparative examples. The drugs used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0020] Example 1

[0021] 2-Methyl-1,2-oxophosphine-5-one 2-oxide and KH550 were mixed in a molar ratio of 1:1 and reacted at 100° C. for 2 hours to obtain a phosphine / silicon amphiphilic compound (OP-KH).

[0022] Take polyvinyl alcohol (PVA) and stir it in distilled water at 90°C until it is completely dissolved to prepare a polyvinyl alcohol aqueous solution with a mass fraction of 10%. Add OP-KH accounting for 30wt% of the total mass of polyvinyl alcohol and phosphine / silicon amphiphilic compounds and boric acid accounting for 3wt% of the mass of PVA to the polyvinyl alcohol aqueous solution at room temperature. Use mechanical stirring until boric acid, OP-KH and PVA become a homogeneous solution. Degas the homogeneous solution and let it stand for 10 minutes. Use a film applicator to apply film on a smooth, clean and dry glass plate. The film is dried in an oven at 100°C for 12 hours to obtain a PVA / OPKH film (i.e., the high-dielectric flame retardant film of the present invention) with a film thickness of 50 microns.

[0023] Example 2

[0024] The metal mold is precisely placed on the film, and nanoimprinting equipment is used for imprinting to produce the microcup structure. The imprinting process includes the following steps: imprinting at a pressure of 200 psi and a temperature of 80 to 95°C for 20 to 30 minutes, then lowering the temperature to 30°C at a rate of 2°C / min, maintaining for 10 minutes, and removing the pressure to obtain a film with a microcup structure.

[0025] Preparation of PVA blank film: PVA was stirred in 90°C distilled water until completely dissolved, and a 10% PVA aqueous solution was prepared. The aqueous solution was degassed and allowed to stand for 0.5 h. On a smooth, clean, dry glass plate, a film was coated using a film applicator. The film was dried in an oven at 70°C for 12 h to obtain a PVA blank film. A microcup structure was prepared according to the above microcup structure preparation method, and was named sample PVA.

[0026] The thin film samples PVA-1, PVA-2 and PVA-3 with microcup structures were prepared according to the amount of the phosphine / silicon amphiphilic compound being 10 wt % to 30 wt % of the total mass of the polyvinyl alcohol and the phosphine / silicon amphiphilic compound.

[0027] The prepared PVA / OP-KH film was evaluated and characterized using GB / T2406-2008 "Test method for combustion performance of plastics - oxygen index method" and GB / T 2408-2008 "Determination of combustion performance of plastics: horizontal method and vertical method". After testing, the limiting oxygen index decibels of samples PVA and PVA-1 were 18.5 and 22.5, and no level was achieved in horizontal combustion, while the combustion levels of PVA-2 and PVA-3 reached UL-94V-0 level, which shows that the phosphine / silicon amphiphilic compound has flame retardant properties, and the addition of the phosphine / silicon amphiphilic compound improves the flame retardant properties of the PVA / OP-KH film, as shown in Table 1.

[0028] Table 1 Flame retardant properties and contact angle of PVA / OP-KH films

[0029]

[0030] The dielectric properties of the PVA / OP-KH film were tested, and the results are shown in Table 2, indicating that the addition of OP-KH greatly improves the dielectric constant of the film.

[0031] Table 2 Dielectric constants of PVA / OP-KH films at different frequencies

[0032]

[0033] Figure 1 The results of the profiler show that the microcup structure of PVA-3 is regular, the microcup is a regular hexagon, the side length of the regular hexagon is 10 to 100 μm, the gap between the regular hexagons is 3 μm, and the height of the regular hexagon of the template is 30 μm. The response time of the PVA / OP-KH film is tested, and the results are shown in Figure 2 The response time of the microcup prepared by pure PVA embossing to the electronic ink is 195ms, while the response time of the microcup with OP-KH added is shortened. When the OP-KH content is 30wt% (PVA-3), the response time is the shortest, which is 44ms. The shorter the response time, the shorter the refresh time of the electronic paper display, the less likely it is to have residual images, and the better the display effect for users. The addition of amphiphilic OP-KH greatly increases the dielectric constant of the PVA film and improves the hydrophobicity of the surface. The high hydrophobic interface can weaken the adhesion between the inorganic electrophoretic particles and the microcup interface, reduce the desorption time of the particles on the surface, and greatly improve the response time when it is applied to the microcup type electronic paper base film.

[0034] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A high dielectric constant flame retardant film, characterized in that: The preparation method is as follows: Polyvinyl alcohol is dissolved in water to obtain a polyvinyl alcohol aqueous solution, a phosphine / silicon amphiphilic compound is added to the polyvinyl alcohol aqueous solution, and then boric acid is added, the mixture is evenly mixed and then applied on a substrate, and a high-dielectric flame-retardant film is obtained after drying.

2. The high dielectric constant flame retardant film according to claim 1, characterized in that: The preparation method of the phosphine / silicon amphiphilic compound is as follows: Take 2-methyl-1,2-phosphino-5-one 2-oxide and KH550 and mix them in a molar ratio of 1:

1. The reaction equation is as follows:

3. The high dielectric constant flame retardant film according to claim 2, characterized in that: The reaction conditions were 100°C for 2 hours.

4. The high dielectric constant flame retardant film according to claim 1, characterized in that: The amount of polyvinyl alcohol is 90wt% to 70wt% of the total mass of polyvinyl alcohol and phosphine / silicon amphiphilic compound, the amount of phosphine / silicon amphiphilic compound is 10wt% to 30wt% of the total mass of polyvinyl alcohol and phosphine / silicon amphiphilic compound, and the amount of boric acid is 3wt% of the mass of polyvinyl alcohol.

5. The high dielectric constant flame retardant film according to claim 4, characterized in that: The amount of polyvinyl alcohol is 90wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, the amount of the phosphine / silicon amphiphilic compound is 30wt% of the total mass of polyvinyl alcohol and the phosphine / silicon amphiphilic compound, and the amount of boric acid is 3wt% of the mass of polyvinyl alcohol.

6. The high dielectric constant flame retardant film according to claim 1, characterized in that: The thickness of the high-dielectric flame-retardant film is 40-50 um.

7. The fast-response electronic paper prepared from the high-dielectric flame-retardant film according to claim 1, characterized in that The preparation method is as follows: A metal template with a microcup structure is constructed using a laser etching method, the metal template is placed on a high-dielectric flame-retardant film, and nanoimprinting equipment is used for imprinting to produce a microcup structure.

8. The fast-response electronic paper prepared from the high-dielectric flame-retardant film according to claim 7, characterized in that: The microcup is a regular hexagon, the side length of the regular hexagon is 10 to 100 μm, the gap between two regular hexagons is 1 to 50 μm, and the height of the microcup is 10 to 50 μm.

9. The fast-response electronic paper prepared from the high-dielectric flame-retardant film according to claim 8, characterized in that: The gap between two regular hexagons is 3 μm, and the height of the regular hexagons of the template is 30 μm.

10. The fast-response electronic paper prepared from the high-dielectric flame-retardant film according to claim 7, characterized in that: The stamping steps are: Under a pressure of 200 psi, the temperature is 80-95°C for 20-30 minutes, and then the temperature is reduced to 30°C at a rate of 2°C / min and maintained for 10 minutes. The pressure is removed to obtain a high dielectric constant flame retardant film with a microcup structure.

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