A flame-retardant optical film with high transmittance and preparation method thereof

Abstract

A flame-retardant optical film with high transmittance and a preparation method thereof. The optical film comprises a black diffusion encapsulation layer, a white diffusion encapsulation layer, a substrate layer, and a surface microstructure layer. The film has good light uniformity and is placed on a light board to solve the problem of uneven color of the light board. The light output color of the display screen including the optical film is uniform, and the optical film has good flame retardant effect.

Description

Technical Field

[0001] The present invention relates to an optical adhesive film, and in particular to an optical adhesive film which has the function of direct LED encapsulation, can improve the consistency of ink color after splicing, has high transmittance after encapsulation and has a flame retardant effect, and a preparation method thereof. Background Art

[0002] In the application of high-definition display technology, Mini LED can be used as a backlight source for large-size displays, smart phones, automotive panels, gaming laptops and other products, and can also be used as a self-luminous display using RGB three-color LED chips. Driven by electronic products such as direct display, backlight and mobile terminals, Mini-LED will usher in a period of rapid development and become a mainstream product of LED display screens.

[0003] With the continuous expansion of the application scenarios of Mini LED displays and people's increasing attention to fire safety, the demand for flame-retardant optical adhesive films continues to increase. However, most optical adhesive films currently do not have flame-retardant effects and cannot meet people's daily life safety needs, which leads to their application being limited in some fields.

[0004] When Mini LED displays are assembled into large screens, they need to be spliced. The differences in the packaging of small LED chips from different batches will cause color differences at the splicing points. In order to improve the problem of inconsistent appearance colors after splicing, the common method is to inkjet the packaging layer again, but the inkjet process also has uniformity problems.

[0005] Traditional packaging generally uses a dispensing process, which is costly and has strict technical requirements. At the same time, because of the use of a hard cured epoxy layer, when the LED chip is damaged and needs to be replaced, the rework process is cumbersome and extremely difficult to operate.

[0006] CN202211118794.2 discloses a Mini LED encapsulation film and a preparation method thereof, wherein the encapsulation film comprises a diffusion film, a semi-transparent OCA, and a release film, wherein the semi-transparent OCA is located between the diffusion film and the release film, and the transmittance of the semi-transparent OCA at 380-500nm is 30-70%. This patent solves the problem of uneven brightness and insufficient filling of the entire surface light source, but the reaction needs to be carried out under nitrogen protection, and the reaction process is cumbersome.

[0007] CN202310913173.1 discloses a Mini LED screen packaging film, preparation method and packaging method, which consists of a three-layer structure, of which the outer two layers are release films and the inner layer is a UV semi-cured adhesive layer. This patent solves the problems of long film making process time, poor thickness uniformity and high warping, but the transmittance is between 30% and 40%, which cannot meet the demand for high transmittance.

[0008] CN202410688073.8 discloses a high-transmittance matte outdoor Mini LED packaging protective film, which includes a release layer, a high-haze optical layer, a substrate layer, a functional layer and a protective layer. This patent has the advantages of high brightness and high transmittance after packaging, but the film material does not have a flame retardant effect and cannot solve the problem of ink color consistency after packaging.

[0009] Therefore, the need to develop an optical adhesive film with high packaging transmittance and flame retardant effect is an industry problem that needs to be solved urgently. Summary of the invention

[0010] In order to solve the problem that the color of the light board is uneven and the packaging film does not have a flame retardant effect, the present invention provides a high-transmittance flame retardant optical film and a preparation method thereof. The optical film has good light uniformity and is placed on the light board to solve the problem of uneven color of the light board. The light color of the display screen including the optical film is uniform, and the optical film has a good flame retardant effect.

[0011] The present invention first provides an optical adhesive film, which includes a black diffusion encapsulation layer 31, a white diffusion encapsulation layer 32, a substrate layer 33, and a surface microstructure layer 34, wherein the white diffusion encapsulation layer is located between the black diffusion encapsulation layer and the substrate layer, wherein the black diffusion encapsulation layer is the first optical surface, the white diffusion encapsulation layer is located above the black diffusion encapsulation layer, and as the second optical surface, the substrate layer is located above the white diffusion encapsulation layer, and the substrate layer is located above the surface microstructure layer, the white diffusion encapsulation layer has a light transmittance of 50%-85%, a thickness of 50-100 μm, and the coating formula of the white diffusion encapsulation layer includes epoxy modified acrylic resin, high temperature curing agent, flame retardant particles and solvent. The flame retardant particles can achieve a good flame retardant effect, and at the same time, through the control of particle size and refractive index, a high haze effect can be achieved simultaneously.

[0012] Furthermore, the light transmittance of the white diffusion encapsulation layer is preferably 60%-80%, more preferably 70%-80%, or 65%, 70%, 75%, which can achieve a good light diffusion effect for the LED lamp beads.

[0013] Furthermore, the thickness of the white diffusion encapsulation layer is preferably 60-100 μm, more preferably 70-90 μm, or 75 μm, 80 μm, or 85 μm. Currently, the height of conventional Mini LED chips is 40-80 μm, and the thickness of the glue layer needs to be able to effectively fill the height of the lamp beads.

[0014] Furthermore, the coating formula of the white diffusion encapsulation layer includes epoxy modified acrylic resin, high temperature curing agent, flame retardant particles and solvent, and the weight ratio of epoxy modified acrylic resin: high temperature curing agent: flame retardant particles: solvent is 75-95 (or 80, 85, 90): 0.05-0.5 (or 0.1, 0.2, 0.3, 0.4): 0.5-10 (or 1, 2, 5, 8): 5-15 (or 8, 10, 12).

[0015] Furthermore, the high temperature curing agent uses an anhydride type, which can be selected from phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride glyceride, and the weight proportion of the curing agent in the glue system of the white diffusion encapsulation layer formula is 0.05-0.5, and more preferably 0.1-0.4. It can be cured at high temperature to increase the crosslinking density of the glue layer.

[0016] Furthermore, the flame retardant particles may be made of one or a mixture of two or more of phosphorus-based, nitrogen-based, aluminum hydroxide, and magnesium hydroxide materials.

[0017] Furthermore, the particle size of the flame retardant particles is controlled to be 0.5 μm-6 μm, and further preferably 1-3 μm, or 2 μm, to achieve a good optical diffusion effect.

[0018] Furthermore, the refractive index of the flame retardant particles is controlled to be 1.40-1.50, and more preferably 1.42-1.45, or 1.43 or 1.44.

[0019] Furthermore, the weight proportion of the flame retardant particles in the white diffusion encapsulation layer formula system is preferably 1-10, more preferably 5-10, or 8.

[0020] Furthermore, the thickness of the black diffusion encapsulation layer is 1-30 μm. Furthermore, when the black diffusion encapsulation layer is a soft adhesive layer, the thickness is preferably 10-20 μm, or 12 μm, 15 μm, or 18 μm.

[0021] Furthermore, the transmittance of the black diffusion encapsulation layer is 5%-20%, or 10%, 15%, the color L value is 20-60, or 25, 30, 35, 40, 45, 50, 55; the a value is -1 to +1, or -0.5, 0, 0.5; the b value is -2 to +1, or -1.5, -1.0, -0.5, 0, 0.5, which can achieve the blackening effect when the LED screen is turned off and improve the uniformity of the appearance color of the spliced ​​display screen.

[0022] Furthermore, the black diffusion encapsulation layer includes a thermally cured modified acrylic resin, a curing agent, flame retardant particles, carbon black, and a solvent.

[0023] Furthermore, the weight ratio of modified acrylic resin, curing agent, flame retardant particles, carbon black and solvent in the black diffusion encapsulation layer is 70-90 (or 75, 80, 85): 0.5-2 (or 1.0, 1.5): 0.5-10 (or 1.0, 2.0, 5.0, 8.0): 0.05-1 (or 0.1, 0.2, 0.5, 0.8): 5-15 (or 8, 10, 12).

[0024] Furthermore, the flame retardant particles may be made of one or a mixture of two or more of phosphorus-based, nitrogen-based, aluminum hydroxide, and magnesium hydroxide materials.

[0025] Furthermore, the particle size of the flame retardant particles is controlled to be 0.5 μm-6 μm, and further preferably 1-3 μm, or 2 μm, to achieve a good optical diffusion effect.

[0026] Furthermore, the refractive index of the flame retardant particles is controlled to be 1.40-1.50, and more preferably 1.42-1.48, or 1.43, 1.45, or 1.47.

[0027] Furthermore, the weight proportion of the flame retardant particles in the black diffusion encapsulation layer formula system is preferably 1-10, more preferably 5-10, or 8.

[0028] Further, the carbon black is inorganic carbon black, organic carbon black or a combination of the two. The inorganic carbon black can be selected from one or more of nano-pigment carbon black, carbon nanotubes, graphene, iron black, copper chromium black. The organic carbon black can be selected from a combination of pigment black 31, organic red, organic yellow, and organic blue.

[0029] Furthermore, the weight proportion of the carbon black in the glue system of the black diffusion encapsulation layer is about 0.05-5, or 0.1-4, or 0.2-2, or 0.5, 1.0, or 1.5.

[0030] Furthermore, the curing agent uses an isocyanate type, which can be selected from one of HDI trimer, TDI trimer, HDI biuret, and IPDI.

[0031] Furthermore, the weight proportion of the curing agent in the glue system of the black diffusion encapsulation layer is about 0.5-0.2, or 1.0, 1.5.

[0032] Furthermore, the solvent is one or a combination of ethyl acetate, toluene, butyl acetate, methyl isobutyl ketone, cyclohexanone, butanone. The weight proportion of the solvent in the glue system of the black diffusion encapsulation layer is 5-15, or 6, 10, or 12.

[0033] Furthermore, when the slit coating method is used, a black adhesive layer is coated on the base film, the solvent is dried in an oven, and then a release film is laminated to obtain a black diffusion encapsulation coating. When the slit coating method is used, the thickness consistency is better.

[0034] Furthermore, the black layer is cured by thermal curing or UV curing.

[0035] Furthermore, the substrate layer is a transparent polymer, and the material is selected from one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), triacetyl cellulose (TAC), cycloolefin polymer (COP), and polyimide (PI). Furthermore, the thickness of the base layer (i.e., the substrate layer) is 25 to 300 μm, and can be 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 188 μm, 250 μm, and 300 μm. The overall light transmittance of the optical adhesive film is about 5%-30%, and the overall appearance is translucent black.

[0036] Furthermore, the surface microstructure layer is a regular or irregular microstructure design, which has a good light diffusion effect. The microstructure mother roller is obtained by mold processing, and this design has better consistency and stability than the matte surface coated with particles.

[0037] Furthermore, the microstructure may be a convex microstructure or a concave microstructure. The rough surface microstructure can reduce the glare on the screen surface caused by ambient light and increase the screen contrast.

[0038] Furthermore, the surface microstructure needs to be designed with a sufficiently high roughness, preferably with a roughness of Ra 1.2-3.0 (or 1.5, 2.0, 2.5). A higher roughness can effectively reduce the glossiness at different angles.

[0039] Furthermore, the glossiness of the surface microstructure is preferably <7 (or 6, 5, 4) at an angle of 60 degrees and <12 (or 10, 9, 7) at an angle of 85 degrees.

[0040] Furthermore, the surface microstructure layer is a particle-free coating with a haze of 40-80% (or 50%, 60%, 70%).

[0041] Furthermore, the microstructure layer is realized by micro-replication through UV embossing, and the structure layer is usually formed by curing acrylic resin.

[0042] The white diffusion encapsulation layer provided by the present invention has high light transmittance, high haze and high viewing angle performance.

[0043] The optical adhesive film provided by the present invention integrates a white diffusion encapsulation layer and a black diffusion encapsulation layer, thereby achieving two functions of LED encapsulation and screen color consistency, and has high encapsulation transmittance and excellent flame retardant effect.

[0044] The conventional packaging of existing LED light panels is epoxy hard coating packaging, which is not easy to rework and does not have a flame retardant effect. The present invention adopts a diffusion packaging layer that can be reworked to solve the problem of difficulty in rework; and the black layer and the packaging diffusion packaging layer are compounded into one to achieve one-time molding and reduce assembly procedures; and flame retardant particles are used instead of conventional diffusion particles to achieve light diffusion and high haze while making the film material have a flame retardant effect.

[0045] The invention provides an optical adhesive film, which comprises a white diffusion encapsulation layer, a black diffusion encapsulation layer (abbreviated as black layer) and a substrate layer; the white diffusion encapsulation layer is formed by encapsulation glue; the encapsulation glue comprises epoxy-modified acrylic resin, a high-temperature curing agent, and flame-retardant particles; the black diffusion encapsulation layer is formed by black glue; the black glue comprises thermally cured modified acrylic resin, a curing agent, flame-retardant particles and carbon black.

[0046] The present invention provides a method for preparing an optical adhesive film, wherein a microstructure is coated on the upper surface of a substrate to prepare a microstructure layer, and a black diffusion encapsulation layer is prepared on the lower surface of the substrate by a wet coating process, which can be achieved by screen printing, slit coating, or doctor blade coating. A white diffusion encapsulation layer is then coated or bonded below the black diffusion encapsulation layer.

[0047] The present invention provides a method for preparing an optical adhesive film, and the method for preparing the optical adhesive film comprises the following steps:

[0048] 1) Using the substrate layer as a support layer, coating the white diffusion encapsulation layer on the lower surface of the substrate layer, and rolling it up to obtain a semi-finished product having only the substrate layer and the white diffusion encapsulation layer;

[0049] 2) using a production device with a first unwinding (first unwinding) coating and a second unwinding (second unwinding) composite film laminating, placing a release film on the first unwinding, and preparing a black diffusion encapsulation layer on the release film by a slit coating method;

[0050] 3) The semi-finished white diffusion encapsulation layer of the first step is placed in the second place, and is online composited with the black diffusion encapsulation layer at the composite film laminating station to obtain the finished optical film. The structure of the finished optical film is as follows Figure 3 shown.

[0051] Furthermore, the method for preparing the optical adhesive film comprises the following steps:

[0052] 1) using the release film as a support layer, coating the white diffusion encapsulation layer on the surface of the release film by a slit coating method, and laminating the surface of the adhesive layer to the substrate, thereby obtaining a semi-finished product containing the substrate layer and the white diffusion encapsulation layer;

[0053] 2) Using a production device with a first unwinding (first unwinding) coating and a second unwinding (second unwinding) composite film laminating, placing a release film in the first unwinding, and using a slit coating method to prepare a black diffusion encapsulation layer on the release film.

[0054] 3) Place the semi-finished product of the white diffusion encapsulation layer in the second stage, remove the release film on the surface of the white layer, and then perform online composite bonding of the black diffusion encapsulation layer and the white diffusion encapsulation layer in the composite film bonding station to obtain a finished optical film. The structure of the finished optical film is as follows Figure 3 shown.

[0055] Further, the method comprises: (1) preparing a surface microstructure mold by precision machining on a polished metal roller through microbead blasting, diamond tool engraving and laser etching; (2) using the microstructure mold to prepare a substrate semi-finished product containing a microstructure by UV embossing micro-replication, and performing coating treatment with the substrate semi-finished product as a supporting layer.

[0056] It should be noted that the method for preparing the black diffusion encapsulation layer of the present invention can be selected according to different equipment and coating formulas, and the present invention does not make a preferred one.

[0057] The invention also provides a display screen, which has the optical adhesive film.

[0058] The invention also provides application of the optical adhesive film in a display screen.

[0059] Compared with the prior art, the optical adhesive film provided by the present invention can realize the direct bonding and encapsulation of micro LEDs using a film sheet, without the need to use liquid encapsulation glue for filling and encapsulation, which greatly improves the convenience of the operation process; at the same time, it has good tearability after encapsulation and has an excellent rework effect. At the same time, the design has a black semi-transparent layer, which has a good covering effect on the micro LED light board and improves the color uniformity and contrast of the light board. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the structure of micro LED, 0 is the LED lamp bead, and 1 is the LED light board.

[0061] Figure 2 This is a schematic diagram of the structure of the traditional LED liquid packaging method. 0 is the LED lamp bead, 1 is the LED lamp board, and 3 is the liquid glue resin used for packaging.

[0062] Figure 3The composition and cross-sectional schematic diagram of the optical adhesive film provided by the present invention includes a first optical surface black encapsulation diffusion encapsulation layer 31, a second optical surface white diffusion encapsulation layer 32, a substrate layer 33, and a surface microstructure layer 34.

[0063] Figure 4 This is a cross-sectional schematic diagram of a micro LED packaged with the optical adhesive film provided by the present invention. 0 is an LED lamp bead, 1 is an LED lamp board, 31 is a black diffusion adhesive layer after being bonded and packaged to the LED, 32 is a white diffusion packaging layer, 33 is a substrate layer, and 34 is a surface microstructure layer. DETAILED DESCRIPTION

[0064] In order to make it easier to understand the structure of the present invention and the functional features and advantages that can be achieved, the preferred embodiments of the present invention are described in detail below with reference to the drawings. It is necessary to point out that this embodiment is only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention.

[0065] The main properties of the optical adhesive films provided in the embodiments and comparative examples of the present invention were tested in the following manner.

[0066] (1) Transmittance after packaging

[0067] First, use a brightness meter to test the brightness of the LED light board without optical film, L1, then stick the optical film on the LED light board for packaging, and then test the brightness of the LED light board after packaging, L2. The transmittance after packaging is calculated as L2 / L1.

[0068] (2) Peel force

[0069] Use a universal tensile testing machine to test the bonding and peeling force between the white diffusion encapsulation layer and the LED light board to evaluate the rework performance. The peeling force is not good if it is too low or too high, and it is most suitable within the range of 1000-2000gf / 25mm.

[0070] (3) Package light board L value test

[0071] The optical films are respectively attached to different LED light panels for packaging, and the L value of the attached surfaces is tested respectively. The lower the L value, the better the blackness.

[0072] (4) Flame retardant test

[0073] Use a flame retardant testing machine to cut the finished film into standard sample sizes, and use the UL94 flame retardant testing standard to conduct vertical and horizontal flame retardant tests. If the film material has excellent flame retardant effect, it can reach V-0 level;

[0074] Example 1

[0075] S1. Prepare a mold with a surface microstructure by precision machining on a polished metal roller by a microbead blasting method; use the microstructure mold to prepare a transparent PET substrate with a microstructure by UV embossing micro-replication, and use the semi-finished substrate as a support layer for coating treatment, and the roughness Ra of the surface microstructure is 1.2;

[0076] S2, add 75 parts of epoxy-modified acrylic resin, 0.5 parts of flame-retardant particles, and 5 parts of solvent into a mixing tank, stir at a speed of 500-1500 r / min for 10 minutes, then add 0.05 parts of high-temperature curing agent, stir at a speed of 500-1500 r / min for 20 minutes, and degas under negative pressure for 30 minutes to obtain a white diffusion encapsulation layer coating liquid;

[0077] S3, add 70 parts of thermosetting modified acrylic resin, 0.5 parts of flame retardant particles, and 5 parts of solvent into a mixing tank, stir at a speed of 500r / min-1500r / min for 10 minutes, then add 0.05 parts of carbon black and 1.6 parts of curing agent, stir at a speed of 500r / min-1500r / min for 20 minutes, and remove bubbles under negative pressure for 30 minutes to obtain a black diffusion encapsulation layer coating liquid;

[0078] S4, using the release film as a support layer, coating the white diffusion encapsulation layer on the surface of the release film by a slit coating method, and at the same time laminating the surface of the adhesive layer with a substrate having a microstructure, to obtain a semi-finished product containing a substrate layer having a microstructure and a white diffusion encapsulation layer;

[0079] S5, using a production device with a first unwinding (first unwinding) coating and a second unwinding (second unwinding) composite film laminating, placing a release film on the first unwinding, and using a slit coating method to prepare a black diffusion encapsulation layer on the release film;

[0080] S6, the semi-finished product of the white diffusion encapsulation layer of the first step is placed in the second place, and is online composited with the black diffusion encapsulation layer at the composite film laminating station to obtain a finished optical film. The structure of the finished optical film is as follows Figure 3 shown.

[0081] Embodiment 2-10

[0082] Based on Example 1, adjust the raw materials, particle size, etc., as shown in Table 1-3.

[0083] Table 1: Proportion of the white diffusion layer of Examples 1-10

[0084]

[0085] Table 2 Proportions of the black diffusion layer of Examples 1-10

[0086]

[0087] Table 3 List of substrate layers of Examples 1-10

[0088]

[0089] Comparative Example 1

[0090] Comparative Example 1 adopts a conventional method, an optical adhesive composition, in parts by weight, includes 60 parts of epoxy resin, 35 parts of curing agent, 4 parts of silicone particles, and 0.5 parts of defoaming agent. The optical adhesive composition is applied to the LED light board by a coating process, and then the optical adhesive composition is cured by a high-temperature molding process, and finally the encapsulated LED light board is placed in a 60-degree oven for 4 hours of curing.

[0091] The performance test results of the finished product of Comparative Example 1 are as follows: after packaging, the transmittance is 35%, the haze is 95%, the L value is 36, the peel force is 3000gf / 25mm, there is a large amount of residual glue during rework and it cannot be reworked, and the flame retardant grade is <HB, and it does not have a flame retardant effect.

[0092] Table 4 Finished product performance table of Examples 1-10

[0093]

[0094] It can be concluded from the main performance test results of the embodiment that the optical adhesive film provided by the present invention has a high transmittance after encapsulating the light board, and the transmittance can reach more than 50%. At the same time, the bottom black diffusion layer plays a black bottom effect, and the overall encapsulation of the light board has a low L value, and the L value can be controlled within 28. In addition, the film adhesive layer of the present invention is added with flame retardant particles. By controlling the material, particle size, and refractive index of the flame retardant particles, a good UL94 V0 flame retardant test effect can be achieved, and the flame retardant particles can also achieve a high haze light diffusion performance of >90.

[0095] It should be noted that the above descriptions are only several typical embodiments of the present invention and are not intended to limit the protection scope of the present invention. All equivalent changes and modifications made based on the content of the present invention are included in the patent scope of the present invention.

Claims

1. An optical adhesive film, comprising a black diffusion encapsulation layer, a white diffusion encapsulation layer, a substrate layer, and a surface microstructure layer, wherein the white diffusion encapsulation layer is located between the black diffusion encapsulation layer and the substrate layer, wherein the black diffusion encapsulation layer is a first optical surface, the white diffusion encapsulation layer is located above the black diffusion encapsulation layer and serves as a second optical surface, the substrate layer is located above the white diffusion encapsulation layer, and above the substrate layer is the surface microstructure layer, the white diffusion encapsulation layer has a light transmittance of 50%-85% and a thickness of 50-100 μm, and the coating formula of the white diffusion encapsulation layer comprises an epoxy-modified acrylic resin, a high-temperature curing agent, flame-retardant particles and a solvent.

2. The optical adhesive film according to claim 1, characterized in that: The light transmittance of the white diffusion encapsulation layer is preferably 60%-80%, and the thickness of the white diffusion encapsulation layer is preferably 60-100 μm.

3. The optical adhesive film according to claim 1, characterized in that: The coating formula of the white diffusion encapsulation layer includes epoxy modified acrylic resin, high temperature curing agent, flame retardant particles and solvent, and the weight ratio of epoxy modified acrylic resin: high temperature curing agent: flame retardant particles: solvent is 75-95:0.05-0.5:0.5-10:5-15.

4. The optical adhesive film according to claim 3, characterized in that: The high temperature curing agent uses anhydride type, which can be selected from phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride glyceride.

5. The optical adhesive film according to claim 3, characterized in that: The flame retardant particles can be made of one or a mixture of two or more of phosphorus, nitrogen, aluminum hydroxide, and magnesium hydroxide materials. The particle size of the flame retardant particles is controlled at 0.5 μm-6 μm, and the refractive index of the flame retardant particles is controlled at 1.40-1.

50.

6. The optical adhesive film according to claim 1, characterized in that: The thickness of the black diffusion packaging layer is 1-30 μm.

7. The optical adhesive film according to claim 1, characterized in that: The light transmittance of the black diffusion encapsulation layer is 5%-20%, the a value is -1 to +1, and the b value is -2 to +1.

8. The optical adhesive film according to claim 1, characterized in that: The black diffusion encapsulation layer comprises a heat-cured modified acrylic resin, a curing agent, flame retardant particles, carbon black, and a solvent, wherein the weight ratio of the modified acrylic resin, the curing agent, the flame retardant particles, the carbon black, and the solvent in the black diffusion encapsulation layer is 70-90: 0.5-2：0.5-10：0.05-1：5-15。 9. The optical adhesive film according to claim 8, characterized in that: The flame retardant particles can be made of one or a mixture of two or more of phosphorus, nitrogen, aluminum hydroxide, and magnesium hydroxide materials. The particle size of the flame retardant particles is controlled at 0.5 μm-6 μm, and the refractive index of the flame retardant particles is controlled at 1.40-1.

50.

10. The optical adhesive film according to claim 8, characterized in that: The carbon black is inorganic carbon black, organic carbon black or a combination of the two. The inorganic carbon black can be selected from one or more of nano-pigment carbon black, carbon nanotubes, graphene, iron black, and copper chromium black. The organic carbon black can be selected from a combination of pigment black 31, organic red, organic yellow, and organic blue.

11. The optical adhesive film according to claim 8, characterized in that: The curing agent uses an isocyanate type, which can be selected from one of HDI trimer, TDI trimer, HDI biuret, and IPDI.

12. The optical adhesive film according to claim 8, characterized in that: The solvent is one or a combination of two of ethyl acetate, toluene, butyl acetate, methyl isobutyl ketone, cyclohexanone and butanone.

13. The optical adhesive film according to any one of claims 1 to 12, characterized in that: The optical adhesive film is prepared by slit coating, a black adhesive layer is coated on the base film, the solvent is dried in an oven, and then a release film is laminated to obtain a black diffusion encapsulation coating.

14. The optical adhesive film according to claim 13, characterized in that: The black diffusion encapsulation layer is cured by thermal curing or UV curing.

15. The optical adhesive film according to claim 1, characterized in that: The substrate layer is a transparent polymer, and the material is selected from one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), triacetyl cellulose (TAC), cycloolefin polymer (COP), and polyimide (PI). The thickness of the substrate layer is 25 to 300 μm.

16. The optical adhesive film according to claim 1, characterized in that: The optical film has an overall light transmittance of about 5% to 30%, and is semi-transparent black in color.

17. The optical adhesive film according to claim 1, characterized in that: The surface microstructure layer is designed in a regular or irregular microstructure.

18. The optical adhesive film according to claim 17, characterized in that: The microstructure may be a convex microstructure or a concave microstructure, and the surface microstructure roughness Ra is 1.2-3.

0.

19. The method for preparing an optical adhesive film according to any one of claims 1 to 18, comprising the following steps: 1) The substrate layer is used as a support layer, and a white diffusion encapsulation layer is formed on the lower surface of the substrate layer, and the substrate layer is rolled up to obtain a semi-finished product having only the substrate layer and the white diffusion encapsulation layer; 2) using a production device with a first unwinding (first unwinding) coating and a second unwinding (second unwinding) composite film laminating, placing a release film on the first unwinding, and preparing a black diffusion encapsulation layer on the release film by a slit coating method; 3) The semi-finished product of the white diffusion encapsulation layer of the first step is placed in the second place, and is online composite-laminated with the black diffusion encapsulation layer at the composite film laminating station to obtain a finished optical film.

20. Use of the optical adhesive film according to any one of claims 1 to 18, in a display screen.

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