High-brightness optical composite film and preparation method thereof

Abstract

The invention discloses a high-brightness optical composite film and a preparation method thereof, and relates to the technical field of optical films. According to the technical scheme, the optical film comprises an upper-layer optical film, a lower-layer optical film and a middle attaching layer, the attaching layer comprises an adhesive layer formed by dotted adhesive particles, linear adhesive strips or compounding of the dotted adhesive particles and the linear adhesive strips, and the covering area of the adhesive layer accounts for 10-50% of the area of the attaching layer; the adhesive layer is prepared from an adhesive, the adhesive is prepared by matching one of a thermocuring pressure-sensitive adhesive and a UV adhesive with plastic particles dispersed in the thermocuring pressure-sensitive adhesive and the UV adhesive, and the plastic particles account for 1-10% of the mass of the thermocuring pressure-sensitive adhesive or the UV adhesive. The problems that a traditional diffusion plate in the display module is large in mass and a traditional composite optical film is large in brightness loss are solved, and the display trend of lightening, thinning and curved surface is met.

Description

Technical Field

[0001] This invention relates to the field of optical film technology, specifically to high-brightness optical composite films and their preparation methods. Background Technology

[0002] In display modules, backlight modules are mainly of two types: edge-lit and direct-lit. In edge-lit backlight modules, the LED light source is placed on the screen bezel, while in direct-lit backlight modules, the LED light source is evenly arranged across the entire back of the screen. Regardless of whether it's a direct-lit or edge-lit backlight module, the light emitted by the LED light source is uneven relative to the entire screen, with brighter areas closer to the light source and darker areas further away. Therefore, a material is needed to evenly disperse this light, ensuring uniform illumination across the entire screen. In direct-lit backlight modules, a diffuser plate combined with an optical film is typically used to disperse the intense light from the LED point light source, transforming it into a uniform surface light source. However, this traditional structure has drawbacks such as generally poor light uniformity and significant thickness, making it unsuitable for the trend towards thinner and more curved display modules.

[0003] In recent years, the technology of laminating multiple optical films into a single multifunctional composite film to replace diffuser plates has become a future development trend. However, composite films prepared using the current full lamination method (i.e., lamination where the adhesive layer covers 100% of the film area) generally suffer from significant brightness loss and mediocre light uniformity.

[0004] Chinese invention patent CN112285814B discloses a high-brightness, high-coverage composite optical film. This composite optical film fully coats and laminates a resin-coated diffusion film and a brightness enhancement film, aiming to improve the coverage of the composite optical film while possessing excellent brightness. However, compared to a single-layer diffusion plate, its brightness is still significantly lower.

[0005] In summary, finding a high-brightness, multifunctional composite film preparation method has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a high-brightness optical composite film and its preparation method to solve the problems of large mass of traditional diffuser plates and large brightness loss of traditional composite optical films in display modules, so as to meet the display trends of thinner and curved surfaces.

[0007] The technical solution of this invention is as follows: On one hand, the present invention provides a high-brightness optical composite film, comprising an upper optical film, a lower optical film, and an intermediate bonding layer. The bonding layer comprises an adhesive layer composed of dot-shaped adhesive particles, linear adhesive strips, or a combination of both, and the adhesive layer covers an area of ​​10-50% of the bonding layer area. The adhesive layer is made of an adhesive, which is formulated by dispersing plastic particles in a combination of thermosetting pressure-sensitive adhesive and UV adhesive. The plastic particles account for 1-10% of the mass of the thermosetting pressure-sensitive adhesive or the UV adhesive.

[0008] Preferably, the lower optical film is a diffusion film, including but not limited to an internally added diffusion film, a coated particle diffusion film, or a microlens array diffusion film.

[0009] Preferably, the upper optical film is a composite brightness enhancement film, including but not limited to diffusion-prism composite film (DOP film), DPP composite brightness enhancement film or microlens-prism composite film (MOP film).

[0010] Preferably, when the adhesive layer is formed from dot-shaped adhesive particles, the shape of the dot-shaped adhesive particles is circular or polygonal, and the arrangement of the dot-shaped adhesive particles is parallel or cross-shaped (e.g., ...). Figure 3 (As shown) or arranged in concentric circles; the width of the dot-shaped colloidal particles is 50-500μm, and the height is 10-50μm. Among them, the width of the dot-shaped colloidal particles refers to the width of its widest point. If the dot-shaped colloidal particles are regular hexagons, the width refers to the length of the diagonal.

[0011] Preferably, when the adhesive layer is formed by linear adhesive strips, the shape of the linear adhesive strips is straight, wavy, broken, or zigzag, and the arrangement of the linear adhesive strips is parallel, cross, or spiral; the line width of the linear adhesive strips is 50-500μm, and the length is 1-30cm.

[0012] Preferably, when the adhesive layer is composed of dot-shaped adhesive particles and linear adhesive strips, the dot-shaped adhesive particles are hexagonal or circular, with a diagonal length of 250-300 μm, arranged in a honeycomb pattern, and occupying 5-25% of the adhesive layer area; the linear adhesive strips are zigzag-shaped, with a line width of 200-250 μm and a pitch of 1-2 mm, and are distributed alternately with the dot-shaped adhesive particles, occupying 5-25% of the adhesive layer area. This composite adhesive layer ensures bonding strength through the dot-shaped adhesive particles and disperses stress through the linear adhesive strips, while simultaneously forming "adhesive layer-air" microchannels to reduce light absorption.

[0013] Preferably, the thermosetting pressure-sensitive adhesive is an acrylic thermosetting pressure-sensitive adhesive; the UV adhesive is a polyurethane UV adhesive; and the solid content of the thermosetting pressure-sensitive adhesive and the UV adhesive is 30-40%.

[0014] Preferably, the plastic particles are PMMA, PS or PET particles with a particle size of 2-10 μm.

[0015] On the other hand, the present invention provides a method for preparing the above-mentioned high-brightness optical composite film, comprising the following steps: S1 applies a primer to the surface of the lower optical film to improve the adhesion between the lower optical film and the bonding layer; S2 uses a roller coating method to coat a bonding layer onto the surface of the lower optical film coated with a primer, followed by baking; S3 covers the upper optical film onto the surface of the bonding layer, and then bonds the upper and lower optical films together; wherein, when the adhesive of the bonding layer is a UV adhesive, it needs to be irradiated with UV light; S4 The composite film obtained in step S3 is subjected to room temperature curing and high temperature curing in sequence to obtain a high brightness optical composite film; the room temperature curing time is 6-24h, the high temperature curing temperature is 40-60℃, and the high temperature curing time is 24-96h.

[0016] Preferably, in step S1, the primer is an acrylate or silane primer; in step S2, the baking temperature is 100-140℃ and the baking time is 1-5 min.

[0017] Compared with the prior art, the present invention has the following advantages: 1. To address the common problem of significant luminance loss in composite optical films prepared using full-lamination coating, this invention employs a roll coating method to apply regularly shaped adhesive layers, such as dot-shaped adhesive particles or linear adhesive strips, between two optical film layers as a bonding layer. By controlling the shape, size, and coverage area of ​​the adhesive layer, the luminance loss caused by bonding can be reduced while maintaining the peel strength between the optical composite films. Experiments have confirmed that when the peel strength of the optical composite film prepared by this invention is ≥264 gf, the luminance remains at 2665 cd / m². 2 The above compares to existing fully laminated solutions (Comparative Example 1, luminance 2316 cd / m²). 2 The brightness is increased by more than 15%. Furthermore, as the coverage area of ​​the adhesive layer in this invention increases, the adhesion of the optical composite film gradually increases, but the brightness gradually decreases. When the coverage area of ​​the adhesive layer is the same, as the size of the adhesive layer increases, the brightness of the optical composite film gradually increases, but the adhesion gradually decreases. Therefore, in order to balance the two properties of brightness and peel strength, the optimal coverage area of ​​the adhesive layer in this invention is 10-50%.

[0018] 2. This invention adds plastic particles to thermosetting pressure-sensitive adhesives or UV adhesives. These randomly distributed plastic particles form a highly efficient network of micro-scatterers. When light passes through an adhesive layer containing a large number of plastic particles, it collides, refracts, and scatters with countless plastic particles. Each scattering changes the direction of light propagation. After countless such random scatterings, the original directionality of the concentrated light is completely disrupted. Finally, the light emitted from the surface of the film becomes very uniform at all angles, thereby improving the uniformity of the optical composite film and achieving a soft and uniform surface light source effect.

[0019] 3. This invention bonds the diffusion film and the composite brightness enhancement film together through an adhesive layer to prepare a multifunctional optical composite film with high brightness and good light uniformity, which can replace the diffuser plate in the direct-lit backlight module. This can significantly reduce the thickness, weight and assembly cost of the backlight module, thereby adapting to the development trend of thinner and curved display modules. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the high-brightness optical composite film of the present invention.

[0021] Figure 2 This is a top view of the dotted adhesive particles arranged in parallel in the bonding layer in this invention.

[0022] Figure 3 This is a top view of the dotted adhesive particles arranged in a cross pattern on the bonding layer in this invention.

[0023] In the diagram, 1 is the upper optical film; 2 is the lower optical film; and 3 is the bonding layer. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0025] Example 1 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0026] S2 uses a roller coating method to coat an adhesive layer 3 onto the surface of the lower diffusion film. The adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. The dot-shaped adhesive particles are circular in shape, with an average diameter of 300 μm and an average height of 20 μm. The dot-shaped adhesive particles are arranged in parallel (e.g., ...). Figure 2As shown), the coverage area is 10% of the bonding layer 3. The adhesive is a 40% solids content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0027] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0028] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain a high-brightness optical composite film, the structure of which is as follows. Figure 1 As shown.

[0029] Example 2 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0030] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm. The particles are arranged in parallel and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0031] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0032] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0033] Example 3 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0034] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm. The particles are arranged in parallel and cover 50% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0035] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0036] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0037] Example 4 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0038] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 100 μm and an average height of 20 μm. The particles are arranged in parallel and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0039] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0040] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0041] Example 5 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0042] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 500 μm and an average height of 20 μm. The particles are arranged in parallel and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0043] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0044] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0045] Example 6 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0046] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of adhesive dots formed by adhesive. The dots are regular pentagons with a diagonal length of 300 μm and an average height of 30 μm. The dots are arranged in a crisscross pattern, covering 30% of the adhesive layer 3. The adhesive is a 30% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ®The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 5 minutes.

[0047] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0048] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0049] Example 7 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0050] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of parallel, straight adhesive strips formed by adhesive, with a line width of 200 μm, an average length of 5 cm, and a coverage area of ​​30% of adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0051] S3 covers the surface of the FHD type membrane with straight adhesive strips with the upper MOP membrane and then attaches them to obtain a composite membrane.

[0052] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0053] Example 8 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0054] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 is composed of dot-shaped adhesive particles and linear adhesive strips formed by adhesive. The dot-shaped adhesive particles are hexagonal in shape, with a diagonal length of 300 μm and an average height of 30 μm, arranged in a honeycomb pattern, covering 20% ​​of the adhesive layer 3 area. The linear adhesive strips are zigzag-shaped, interspersed with the dot-shaped adhesive particles, with a line width of 250 μm and a pitch of 1 mm, covering 10% of the adhesive layer 3 area. The adhesive is a 40% solids content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0055] S3 covers the surface of the FHD type membrane with the upper MOP membrane and then laminates them to obtain a composite membrane.

[0056] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0057] Example 9 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0058] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 2μm and the PMMA particles account for 10% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0059] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0060] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0061] Example 10 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0062] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 10 μm and the PMMA particles account for 2% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0063] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0064] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0065] Example 11 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0066] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0067] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0068] S4 After curing the composite film at room temperature for 24 hours, it is then cured at 60°C for 96 hours to obtain a high-brightness optical composite film.

[0069] Example 12 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 applies a 200nm thick acrylic primer (Acronal® LR 8888, BASF) to the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0070] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. The adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. The dot-shaped adhesive particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and covering an area of ​​30% of the adhesive layer 3. The adhesive is formulated with a 40% solids content polyurethane UV adhesive (Ebecryl® 800, DSM) and PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and account for 5% of the mass of the polyurethane UV adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0071] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together, while simultaneously subjecting it to UV irradiation to obtain a composite membrane.

[0072] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the high-brightness optical composite film.

[0073] Example 13 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0074] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 is composed of a composite of adhesive dots and linear adhesive strips. The adhesive dots are circular, 300 μm in diameter, 10 μm in height, and cover 15% of the adhesive layer 3. The linear adhesive strips are zigzag-shaped, interspersed with the adhesive dots, with a line width of 250 μm, a length of 1 cm, a pitch of 1 mm, and also cover 15% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ®The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0075] S3 covers the surface of the FHD type membrane with the upper MOP membrane and then laminates them to obtain a composite membrane.

[0076] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain a high-brightness optical composite film, the structure of which is as follows. Figure 1 As shown.

[0077] Example 14 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0078] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 is composed of a composite of adhesive dots and linear adhesive strips. The adhesive dots are circular, 300 μm in diameter, and 50 μm in height, covering 15% of the adhesive layer 3. The linear adhesive strips are zigzag-shaped, interspersed with the adhesive dots, with a line width of 200 μm, a length of 30 cm, a pitch of 1 mm, and covering 15% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0079] S3 covers the surface of the FHD type membrane with the upper MOP membrane and then laminates them to obtain a composite membrane.

[0080] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain a high-brightness optical composite film, the structure of which is as follows. Figure 1 As shown.

[0081] Example 15 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0082] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The adhesive was formulated with WS-5000 (Mitsui Chemicals, Inc.) and dispersed PS particles, the PS particles having a particle size of 5 μm and comprising 5% of the adhesive mass. The FHD film containing the adhesive was then placed in an oven and baked at 120°C for 2 minutes.

[0083] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0084] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain a high-brightness optical composite film, the structure of which is as follows. Figure 1 As shown.

[0085] Example 16 The method for preparing the high-brightness optical composite film in this embodiment includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0086] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The adhesive is formulated with WS-5000 (Mitsui Chemicals Co., Ltd.) and dispersed PET particles, the PET particles having a particle size of 5 μm and the PET particles accounting for 5% of the adhesive mass. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0087] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0088] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 40°C for 24 hours to obtain the high-brightness optical composite film.

[0089] Comparative Example 1 The preparation method of the optical composite film of Comparative Example 1 includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0090] S2 uses a roller coating method to coat the surface of the lower diffusion film with adhesive, which is a 40% solids content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 5 minutes.

[0091] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0092] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the optical composite film.

[0093] Comparative Example 2 The preparation method of the optical composite film in Comparative Example 2 includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0094] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm, arranged in parallel, and cover 30% of the adhesive layer 3. The adhesive used is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® WS-5000 (Mitsui Chemicals Co., Ltd.). The FHD film with adhesive was then placed in an oven and baked at 120°C for 5 minutes.

[0095] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0096] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the optical composite film.

[0097] Comparative Example 3 Comparative Example 3 uses a commercial diffusion plate (RS350H, Guangdong Ruijie New Materials Co., Ltd.) as the optical composite film.

[0098] Comparative Example 4 The preparation method of the optical composite film in Comparative Example 4 includes the following steps: The upper MOP film is directly covered on the surface of the lower FHD film and bonded together by physical pressure.

[0099] Comparative Example 5 The preparation method of the optical composite film of Comparative Example 5 includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0100] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm. The particles are arranged in parallel and cover 60% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0101] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0102] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the optical composite film.

[0103] Comparative Example 6 The preparation method of the optical composite film of Comparative Example 6 includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0104] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm. The particles are arranged in parallel and cover 10% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 5 μm and the PMMA particles account for 15% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0105] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0106] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the optical composite film.

[0107] Comparative Example 7 The preparation method of the optical composite film of Comparative Example 7 includes the following steps: S1 has a 200nm thick layer of silane primer (KBM-403, Shin-Etsu Chemical Industry Co., Ltd.) coated on the surface of the lower diffusion film (FHD type film, Ningbo Changyang Technology Co., Ltd.).

[0108] S2 uses a roller coating method to apply an adhesive layer 3 to the surface of the lower diffusion film. Adhesive layer 3 consists of dot-shaped adhesive particles formed by adhesive. These particles are circular, with an average diameter of 300 μm and an average height of 20 μm. The particles are arranged in parallel and cover 10% of the adhesive layer 3. The adhesive is a 40% solids-content acrylic thermosetting pressure-sensitive adhesive (Takelac). ® The FHD film (WS-5000, Mitsui Chemicals Co., Ltd.) is formulated with PMMA particles dispersed therein. The PMMA particles have a particle size of 15 μm and the PMMA particles account for 5% of the mass of the acrylic thermosetting pressure-sensitive adhesive. The FHD film with the adhesive is then placed in an oven and baked at 120°C for 2 minutes.

[0109] S3 involves covering the surface of the FHD type membrane with dotted adhesive particles onto the upper MOP membrane and bonding them together to obtain a composite membrane.

[0110] S4 After curing the composite film at room temperature for 6 hours, it is then cured at 60°C for 48 hours to obtain the optical composite film.

[0111] The optical composite films prepared in Examples 1-16 and Comparative Examples 1-7 were subjected to performance tests, and the test methods are as follows: Luminance: Tested using a luminance meter, model BM-7A.

[0112] Peel strength: Tested according to GB / T 2792-2014 Adhesive tape peel strength, using a universal testing machine at a test speed of 300 mm / min.

[0113] Uniformity: Uniformity is characterized by homogeneity, which is the ratio of minimum luminance to maximum luminance. Nine points are measured and the average value is taken.

[0114] The test results are shown in Table 1-2: Table 1 Performance test results of the optical composite films prepared in Examples 1-16

[0115] Table 2 Performance test results of the optical composite films prepared in Comparative Examples 1-7

[0116] As can be seen from Tables 1-2, compared with the examples and other comparative examples, Comparative Example 3, which uses a single-layer diffuser plate, and Comparative Example 4, which uses two layers of optical films directly pressure-bonded, have the highest measured luminance, which is 2895 cd / m². 2 2890cd / m 2 As shown in Comparative Example 1 and Examples 1-3, the luminance of the prepared optical composite film gradually decreases with the increase of the adhesive layer coverage area. When the coverage area reaches 100%, i.e., the optical composite film prepared by full coating and full lamination in Comparative Example 1, its luminance is the lowest. Compared with the single-layer diffuser plate of Comparative Example 3, the luminance loss rate of the optical composite film in Comparative Example 1 reaches 20%. The reason for this may be that the adhesive layer absorbs some of the light from the light source, resulting in a reduction in the light flux transmitted through the optical composite film, thus leading to a decrease in luminance. However, if the adhesive layer coverage area is too small, the adhesion between the upper optical film 1 and the lower optical film 2 is too weak, which may lead to the risk of film separation. In order to balance the luminance and adhesion of the optical composite film, this invention selects an adhesive layer coverage area of ​​10-50% as optimal, which maintains a high level of luminance while having good adhesion. In Comparative Example 5, the adhesive layer coverage area was too high (60%). Although the peel strength of the optical composite film was very high, the brightness dropped to 2550 cd / m², resulting in poor overall performance.

[0117] As demonstrated in Examples 2, 4, and 5, when the coverage area of ​​the adhesive layer is the same, the size of the dot-shaped adhesive particles also affects the brightness and adhesion of the optical composite film. When the particle size is small, i.e., small-sized, high-density adhesive particles are used to achieve the required coverage area, the bonding layer 3 will generate more and more complex colloid / air / film interfaces, resulting in more complex scattering. This may cause some of the light that should have been brightened to deviate from the optimal path, causing light loss and reducing brightness. When the particle size is large, i.e., large-sized, low-density adhesive particles are used to achieve the required coverage area, the scattering effect on light is weaker, the interference with the collimation function of the composite brightness enhancement film is smaller, and the impact on brightness is also smaller. Therefore, for brightness variation, large-sized, low-density dot-shaped adhesive particles are better. However, if large-sized, low-density dot-shaped adhesive particles are used, stress will be highly concentrated at the edges where each large particle connects to the film, leading to decreased adhesion. Conversely, if small-sized, high-density dot-shaped adhesive particles are used, stress will be dispersed across a large number of small particles, and the stress concentration effect at the edges of each small particle will be much weaker, resulting in significantly increased adhesion compared to large-sized dot-shaped particles. In conclusion, to balance the brightness and adhesion of optical composite films, it is necessary to select an appropriate dot-shaped adhesive particle size.

[0118] As demonstrated in Examples 6-8 and 13-14, when the coverage area of ​​the adhesive layer remains constant, changing the shape, arrangement, and size of the adhesive layer has a relatively small impact on the brightness of the optical composite film (fluctuation range within 20 cd / m²), but it will affect the peel strength of the optical composite film to some extent. Sharp shapes (such as regular pentagons) or excessively tall adhesive particles (such as 50 μm) may lead to stress concentration or changes in contact area, thereby causing fluctuations in peel strength.

[0119] As shown in Comparative Example 2 and Example 2, the peel strength of the optical composite film decreases when plastic particles are added to the adhesive. This is because the plastic particles do not have an adhesive effect, and there are more stress concentration points between the plastic particles and the adhesive. However, adding plastic particles also increases the uniformity of the optical composite film. This is mainly because the refractive indices of the adhesive and the plastic particles are different, resulting in more light scattering and making the overall surface light more uniform. As shown in Examples 2, 9, and 10, the content and particle size of plastic particles have a complex effect on performance. Generally, the higher the content and the smaller the particle size, the more scattering points and the better the uniformity; however, too many plastic particles will severely disrupt the continuity of the adhesive layer, leading to a significant decrease in peel strength (e.g., in Comparative Example 6, the plastic particle content was 15%, and the peel strength was only 150 gf). In Example 2, the plastic particle content was 5% and the particle size was 5 μm, achieving the best balance between brightness, peel strength, and uniformity. The plastic particles in Comparative Example 7 have a particle size of 15 μm. Due to the excessively large particle size, the scattering efficiency is reduced, and the uniformity is only 86%, which is not as good as that of small-particle-size plastic particles.

[0120] As shown in Examples 1 and 11, extending the curing time has no significant effect on the brightness of the optical composite film, but it increases the peel strength; however, extending the curing time also leads to reduced production efficiency and increased costs, so a trade-off needs to be struck. As shown in Examples 1 and 12, replacing the acrylic thermosetting pressure-sensitive adhesive with a polyurethane UV adhesive has no significant effect on the brightness, peel strength, and uniformity of the optical composite film. Examples 15 and 16 demonstrate that plastic particles of different materials can achieve the effects of this invention, and the products remain qualified under different curing conditions, verifying the rationality of the process parameters of this invention.

[0121] In summary, this invention, through specific dot-shaped and line-shaped adhesive layer structure design and the addition of plastic particles, successfully solves the contradiction between large brightness loss and poor light uniformity of traditional optical composite films, and provides a high-performance optical composite film.

Claims

1. A high-brightness optical composite film, characterized in that, It includes an upper optical film (1), a lower optical film (2) and an intermediate bonding layer (3). The bonding layer (3) includes an adhesive layer composed of dot-shaped adhesive particles, linear adhesive strips or a combination of both. The adhesive layer covers an area of ​​10-50% of the area of ​​the bonding layer (3). The adhesive layer is made of an adhesive, which is formulated by dispersing plastic particles in a combination of thermosetting pressure-sensitive adhesive and UV adhesive. The plastic particles are 1-10% of the mass of the thermosetting pressure-sensitive adhesive or UV adhesive.

2. The high-brightness optical composite film as described in claim 1, characterized in that, The lower optical film (2) is a diffusion film.

3. The high-brightness optical composite film as described in claim 1, characterized in that, The upper optical film (1) is a composite brightening film.

4. The high-brightness optical composite film as described in claim 1, characterized in that, When the adhesive layer is formed by dot-shaped adhesive particles, the shape of the dot-shaped adhesive particles is circular or polygonal, and the arrangement of the dot-shaped adhesive particles is parallel, cross-shaped, or concentric; the width of the dot-shaped adhesive particles is 50-500μm, and the height is 10-50μm.

5. The high-brightness optical composite film as described in claim 1, characterized in that, When the adhesive layer is formed by linear adhesive strips, the shape of the linear adhesive strips can be straight, wavy, broken, or zigzag, and the arrangement of the linear adhesive strips can be parallel, cross, or spiral; the line width of the linear adhesive strips is 50-500μm, and the length is 1-30cm.

6. The high-brightness optical composite film as described in claim 1, characterized in that, When the adhesive layer is composed of dot-shaped adhesive particles and linear adhesive strips, the dot-shaped adhesive particles are hexagonal or circular, with a diagonal length of 250-300μm, arranged in a honeycomb pattern, accounting for 5-25% of the area of ​​the adhesive layer (3); the linear adhesive strips are zigzag, with a line width of 200-250μm and a pitch of 1-2mm, and are distributed alternately with the dot-shaped adhesive particles, accounting for 5-25% of the area of ​​the adhesive layer (3).

7. The high-brightness optical composite film as described in claim 1, characterized in that, The thermosetting pressure-sensitive adhesive is an acrylic thermosetting pressure-sensitive adhesive; the UV adhesive is a polyurethane UV adhesive; the solid content of the thermosetting pressure-sensitive adhesive and the UV adhesive is 30-40%.

8. The high-brightness optical composite film as described in claim 1, characterized in that, The plastic particles are PMMA, PS, or PET particles with a particle size of 2-10μm.

9. The method for preparing the high-brightness optical composite film according to any one of claims 1-8, characterized in that, Includes the following steps: S1 coats a primer onto the surface of the lower optical film (2); S2 uses a roller coating method to coat a bonding layer (3) onto the surface of the lower optical film (2) coated with a primer, and then bakes it; S3 covers the upper optical film (1) on the surface of the bonding layer (3) and bonds the upper optical film (1) and the lower optical film (2); wherein, when the adhesive of the bonding layer (3) is a UV adhesive, it needs to be irradiated with UV. S4 The composite film obtained in step S3 is subjected to room temperature curing and high temperature curing in sequence to obtain a high brightness optical composite film; the room temperature curing time is 6-24h, the high temperature curing temperature is 40-60℃, and the high temperature curing time is 24-96h.

10. The method for preparing the high-brightness optical composite film as described in claim 9, characterized in that, In step S1, the primer is an acrylate or silane primer; in step S2, the baking temperature is 100-140℃ and the baking time is 1-5 min.

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