Circularly polarized optical film compounded with specially processed birefringent particles

Abstract

The invention discloses a circular polarization optical film compounded with specially treated birefringent particles, which comprises a base material layer, a birefringent particle adhesive layer, an upper adhesive layer and a lower adhesive layer, and is characterized in that the base material layer is uniformly coated with the adhesive layer mixed with specially treated birefringent particles. The preparation method comprises the following steps: preparing particles, uniformly mixing the particles with an adhesive according to a mass fraction of 5-35% to obtain a slurry, coating two surfaces of a substrate with the mixed slurry, carrying out thermosetting molding, and coating or oppositely pasting the adhesive to the upper layer and the lower layer of the material, and the film is compounded with the specially treated birefringence particles, so that higher-efficiency conversion from linear polarized light to circular polarized light can be achieved without 45-degree cutting.

Description

Technical Field

[0001] This invention relates to the field of electronic display device technology, specifically to a circularly polarized optical film with specially treated birefringent particles. Background Technology

[0002] Currently, the light emitted by LCD screens on the market is linearly polarized light. Linearly polarized light refers to light whose electric field vector vibrates in a fixed direction within a plane perpendicular to the direction of propagation. Exposure to uneven light in the same direction can easily cause visual fatigue. In contrast, the electric field vector of circularly polarized light rotates in a circle along the direction of propagation, which is closer to natural light and thus reduces visual fatigue. Currently, there are two main solutions for circularly polarized eye protection technology. The first solution, QWP, uses liquid crystal or birefringent crystal materials to prepare a 1 / 4 waveplate layer to change the light path and convert linearly polarized light into circularly polarized light. However, the QWP solution is expensive and has a high degree of binding with the polarizer. The second solution involves cutting a high phase difference film, such as an SRF film, at 45° and bonding it to the polarizer to achieve circular polarization. However, high phase difference films are currently mainly imported, which are expensive, and the specific 45° cutting process reduces the utilization rate of the film, further increasing the cost. Therefore, we need a circularly polarized optical film with specially treated birefringent particles.

[0003] The circularly polarized optical films currently in use are difficult to obtain, have high costs, are cumbersome to operate, and have low conversion efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a circularly polarized optical film with composite specially treated birefringent particles to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A circularly polarized optical film with specially treated birefringent particles comprises a substrate layer, a birefringent particle adhesive layer, and upper and lower adhesive layers. The substrate layer is coated on both sides with a specially treated birefringent particle adhesive layer. The substrate layer is made of polyethylene terephthalate film material processed by a special process. The upper and lower adhesive layers are one or more mixtures of acrylic or polyurethane adhesives with a refractive index of 1.4 to 1.6.

[0007] Preferably, the optical substrate film after substrate layer treatment has a birefringence Δn ≥ 0.055, a phase retardation δ ≥ 2.75 μm, and a center wavelength number in the visible light band ≥ 10.

[0008] Preferably, the adhesive layer comprises specially treated birefringent particles and an adhesive, wherein the specially treated birefringent particles account for 5% to 35% of the mass fraction of the birefringent particle adhesive layer.

[0009] Preferably, the birefringent particles include one or more of Iceland spar, calcite, quartz, magnesium fluoride, quartz, yttrium vanadate, and lithium niobate.

[0010] Preferably, the adhesive is a thermosetting adhesive with a refractive index of 1.48 to 1.7.

[0011] Preferably, the special treatment includes controlling the distribution of birefringent particles within an optimized particle size range with higher circular deflection conversion efficiency and performing surface treatment on the birefringent particles.

[0012] Preferably, the control of birefringent particle distribution within an optimized particle size range with higher circular deflection conversion efficiency is characterized by first performing theoretical calculations to determine the particle size range (3 / 4*λ) / △n≤d=[(2m+1)*1 / 4*λ] / △n≤10um, and then obtaining the optimized range powder through wet or dry grading and sieving.

[0013] Preferably, the surface treatment uses a surface treatment agent, which includes one or more of titanate coupling agents, aluminate coupling agents, stearic acid and its salts, and phosphate esters. During the classification process, a surface modifier is added at a mass fraction of 0.1% to 2.5% of the birefringent particle powder. The molten or solution-state surface modifier is slowly added to the high-speed rotating and classifying powder by spraying or dripping.

[0014] A circularly polarized optical film with specially treated birefringent particles includes the following steps:

[0015] S1. Preparation of a mixture of birefringent particles and adhesive: After screening and surface treatment of birefringent particle powder such as calcite, it is added to thermosetting adhesive according to a certain mass fraction and mixed evenly by high-speed rotation.

[0016] S2. The mixture of birefringent particles and adhesive is applied to both sides of the PET substrate and cured at a certain temperature.

[0017] S3. Finally, apply acrylic or polyurethane adhesive layers to the top and bottom of the material from step S2, or attach them together, and then UV mold them at a certain energy.

[0018] S4. Perform circular polarization conversion spectroscopy tests on the prepared circularly polarized optical films of each comparative example and embodiment. Adjust the display device to the standard working state and operate it in the standard working state for 30 minutes. Input a 100% full white field test screen. Place the circularly polarized optical film tightly against the screen surface and place a linear polarizer (polarization degree ≥ 99.9) with polarization angle markings above the circularly polarized optical film. Finally, rotate the polarization angle of the polarizer by 360° and record the spectral radiation energy E(λ) of the center point in the 380nm~780nm band at 15° intervals when the screen is 100% full white field. The unit is W / (sr·m2·nm). A total of 24 sets of spectral data are obtained. Take the maximum brightness and minimum brightness at each wavelength under the 24 sets of spectral data to obtain Emax(λ) and Emin(λ). Calculate the depolarization rate at each wavelength and the average depolarization rate of the entire band at all wavelengths.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. By subjecting the coated birefringent particles to special treatment and controlling their distribution within an optimized particle size range that yields higher circular polarization conversion efficiency, and by modifying the surface to better disperse them in the adhesive layer, the circular polarization optical film composited with specially treated birefringent particles exhibits better circular polarization conversion performance. Furthermore, compared to existing technologies that rely on imported high phase difference films, the substrate in this invention is readily available, and the preparation process does not require specific angle cutting, thus reducing and simplifying costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structural parameters of a comparative example and embodiment of a circularly polarized optical film with specially treated birefringent particles according to the present invention.

[0022] Figure 2 This is a schematic diagram showing the light transmittance and average circular polarization conversion efficiency of a circularly polarized optical film with specially treated birefringent particles according to the present invention.

[0023] Figure 3 This is a spectral test image of a circularly polarized optical film with specially treated birefringent particles in the visible light band, as shown in Comparative Example 1 of the present invention.

[0024] Figure 4 The visible light spectrum of Comparative Example 2 shows the circular polarization optical film of a composite specially treated birefringent particles according to the present invention.

[0025] Figure 5 This is a spectral test image of Example 1 of the present invention, which is a circularly polarized optical film with specially treated birefringent particles in the visible light band.

[0026] Figure 6This is a spectral test image of Example 2 of the present invention, which is a circularly polarized optical film with specially treated birefringent particles.

[0027] Figure 7 This is a spectral test image of Example 3 of the present invention, which is a circularly polarized optical film with specially treated birefringent particles in the visible light band.

[0028] Figure 8 This is a spectral test image of Example 4 of the present invention, which is a circularly polarized optical film with specially treated birefringent particles.

[0029] In the diagram: 1. Substrate layer; 2. Birefringent particle adhesive layer; 3. Upper and lower adhesive layers. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1 - Figure 8 This invention provides a technical solution for a circularly polarized optical film composed of specially treated birefringent particles:

[0032] A circularly polarized optical film with specially treated birefringent particles includes a substrate layer 1, a birefringent particle adhesive layer 2, and upper and lower adhesive layers 3. The substrate layer 1 is coated on both sides with a mixture of specially treated birefringent particle adhesive layers 2. The substrate layer 1 is made of polyethylene terephthalate film material processed by a special process. The upper and lower adhesive layers 3 are one or more mixtures of acrylic or polyurethane adhesives with a refractive index of 1.4 to 1.6.

[0033] After treatment of substrate layer 1, the birefringence Δn of the optical substrate layer film is ≥0.055, the phase retardation δ is ≥2.75um, and the number of center wavelengths in the visible light band is ≥10.

[0034] The adhesive layer contains specially treated birefringent particles and adhesive, with the specially treated birefringent particles accounting for 5% to 35% of the mass of the birefringent particle adhesive layer 2.

[0035] The types of birefringent particles include Iceland spar, calcite, quartz, magnesium fluoride, quartz, yttrium vanadate, and lithium niobate, or one or more of these.

[0036] The adhesive is a thermosetting adhesive with a refractive index of 1.48 to 1.7.

[0037] The special treatment includes controlling the distribution of birefringent particles within an optimized particle size range that has a higher circular deflection conversion efficiency and performing surface treatment on the birefringent particles.

[0038] The method for controlling the distribution of birefringent particles within an optimized particle size range with higher circular deflection conversion efficiency is characterized by first performing theoretical calculations to determine the particle size range (3 / 4*λ) / △n≤d=[(2m+1)*1 / 4*λ] / △n≤10um, and then obtaining the optimized range powder through wet or dry classification and sieving.

[0039] Surface treatment uses surface treatment agents, including titanate coupling agents, aluminate coupling agents, stearic acid and its salts, and one or more phosphate esters. During the classification process, a surface modifier is added at a mass fraction of 0.1% to 2.5% of the birefringent particle powder. The molten or solution-state surface modifier is slowly added to the high-speed rotating and classifying powder by spraying or dripping.

[0040] A circularly polarized optical film with specially treated birefringent particles includes the following steps:

[0041] S1. Preparation of a mixture of birefringent particles and adhesive: After screening and surface treatment of birefringent particle powder such as calcite, it is added to thermosetting adhesive according to a certain mass fraction and mixed evenly by high-speed rotation.

[0042] S2. The mixture of birefringent particles and adhesive is applied to both sides of the PET substrate and cured at a certain temperature.

[0043] S3. Finally, apply acrylic or polyurethane adhesive layers to the top and bottom of the material from step S2, or attach them together, and then UV mold them at a certain energy.

[0044] S4. Perform circular polarization conversion spectroscopy tests on the prepared circularly polarized optical films of each comparative example and embodiment. Adjust the display device to the standard working state and operate it in the standard working state for 30 minutes. Input a 100% full white field test screen. Place the circularly polarized optical film tightly against the screen surface and place a linear polarizer (polarization degree ≥ 99.9) with polarization angle markings above the circularly polarized optical film. Finally, rotate the polarization angle of the polarizer by 360° and record the spectral radiation energy E(λ) of the center point in the 380nm~780nm band at 15° intervals when the screen is 100% full white field. The unit is W / (sr·m2·nm). A total of 24 sets of spectral data are obtained. Take the maximum brightness and minimum brightness at each wavelength under the 24 sets of spectral data to obtain Emax(λ) and Emin(λ). Calculate the depolarization rate at each wavelength and the average depolarization rate of the entire band at all wavelengths.

[0045] It should be noted that this invention is a circularly polarized optical film composed of specially treated birefringent particles. In its use, preparation is first carried out using comparative examples and embodiments: First, the birefringent particles are subjected to particle size optimization sieving and surface treatment. Then, the particles are uniformly mixed with an adhesive at a certain mass fraction to obtain a slurry. The mixed slurry is coated on both sides of a substrate and thermoset. Finally, the adhesive is coated or bonded to the upper and lower layers of the material. The film of this invention, composed of specially treated birefringent particles, can achieve higher efficiency in converting linearly polarized light to circularly polarized light without the need for 45° cutting. After the circularly polarized optical films of each comparative example and embodiment are prepared, circular polarization conversion spectroscopy tests are performed. The display device is adjusted to standard operating conditions and operates under standard operating conditions for 30 minutes. For 10 minutes, input a 100% full white field test image, place the circularly polarized optical film tightly against the screen surface, and place a linear polarizer (polarization degree ≥ 99.9) with polarization angle markings above the circularly polarized optical film. Finally, rotate the polarizer 360° at 15° intervals and record the spectral radiation energy E(λ) of the center point in the 380nm~780nm band at each angle when the 100% full white field image is displayed. The unit is W / (sr·m2·nm). A total of 24 sets of spectral data are obtained. The maximum and minimum brightness at each wavelength are taken from the 24 sets of spectral data to obtain Emax(λ) and Emin(λ). The depolarization rate at each wavelength is calculated, and the average depolarization rate across the entire band at all wavelengths is obtained. Finally, the most suitable ratio preparation method is selected to prepare a circularly polarized optical film with composite specially treated birefringent particles.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circularly polarized optical film composed of specially treated birefringent particles, characterized in that: It includes a substrate layer (1), a birefringent particle adhesive layer (2) and upper and lower adhesive layers (3). The substrate layer (1) is coated on both sides with a specially treated birefringent particle adhesive layer (2). The substrate layer (1) is made of polyethylene terephthalate film material processed by a special process. The upper and lower adhesive layers (3) are one or more of acrylic or polyurethane adhesives with a refractive index of 1.4 to 1.

6.

2. The circularly polarized optical film with specially treated birefringent particles according to claim 1, characterized in that: The optical substrate film after the substrate layer (1) is treated has a birefringence Δn ≥ 0.055, a phase delay δ ≥ 2.75 μm, and a center wavelength number in the visible light band ≥ 10.

3. The circularly polarized optical film with composite specially treated birefringent particles according to claim 1, characterized in that: The adhesive layer contains specially treated birefringent particles and adhesive, with the specially treated birefringent particles accounting for 5% to 35% of the mass fraction of the birefringent particle adhesive layer (2).

4. The circularly polarized optical film with composite specially treated birefringent particles according to claim 3, characterized in that: The birefringent particles include one or more of Iceland spar, calcite, quartz, magnesium fluoride, quartz, yttrium vanadate, and lithium niobate.

5. A circularly polarized optical film with specially treated birefringent particles as described in claim 3, characterized in that: The adhesive is a thermosetting adhesive with a refractive index of 1.48 to 1.

7.

6. The circularly polarized optical film with composite specially treated birefringent particles according to claim 1, characterized in that: The special treatment includes controlling the distribution of birefringent particles within an optimized particle size range that has a higher circular deflection conversion efficiency and performing surface treatment on the birefringent particles.

7. A circularly polarized optical film with composite specially treated birefringent particles according to claim 6, characterized in that: The method of controlling the distribution of birefringent particles within an optimized particle size range with higher circular deflection conversion efficiency is characterized by first performing theoretical calculations to determine the particle size range (3 / 4*λ) / △n≤d=[(2m+1)*1 / 4*λ] / △n≤10um, and then obtaining the optimized range powder through wet or dry grading and sieving.

8. A circularly polarized optical film with composite specially treated birefringent particles according to claim 6, characterized in that: The surface treatment uses a surface treatment agent, which may include one or more of titanate coupling agents, aluminate coupling agents, stearic acid and its salts, and phosphate esters. During the classification process, a surface modifier is added at a mass fraction of 0.1% to 2.5% of the birefringent particle powder. The molten or solution-state surface modifier is slowly added to the high-speed rotating and classifying powder by spraying or dripping.

9. A circularly polarized optical film composed of specially treated birefringent particles, characterized in that: Includes the following steps: S1. Preparation of a mixture of birefringent particles and adhesive: After screening and surface treatment of birefringent particle powder such as calcite, it is added to thermosetting adhesive according to a certain mass fraction and mixed evenly by high-speed rotation. S2. The mixture of birefringent particles and adhesive is applied to both sides of the PET substrate and cured at a certain temperature. S3. Finally, apply acrylic or polyurethane adhesive layers to the top and bottom of the material from step S2, or attach them together, and then UV mold them at a certain energy. S4. Perform circular polarization conversion spectroscopy tests on the prepared circularly polarized optical films of each comparative example and embodiment. Adjust the display device to the standard working state and operate it in the standard working state for 30 minutes. Input a 100% full white field test screen. Place the circularly polarized optical film tightly against the screen surface and place a linear polarizer (polarization degree ≥ 99.9) with polarization angle markings above the circularly polarized optical film. Finally, rotate the polarization angle of the polarizer by 360° and record the spectral radiation energy E(λ) of the center point in the 380nm~780nm band at 15° intervals when the screen is 100% full white field. The unit is W / (sr·m2·nm). A total of 24 sets of spectral data are obtained. Take the maximum brightness and minimum brightness at each wavelength under the 24 sets of spectral data to obtain Emax(λ) and Emin(λ). Calculate the depolarization rate at each wavelength and the average depolarization rate of the entire band at all wavelengths.

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