A four-sided adhesive process for a diffusion film

Abstract

This invention discloses a four-sided adhesive backing process for diffusion films, belonging to the field of optical film technology. By optimizing and thickening the double-layer silicone release film, combined with asynchronous die-cutting, precise alignment of positioning holes, and integral one-time die-cutting, this invention completely solves the pain points of traditional diffusion films, such as double-sided adhesive backing, easy adhesive misalignment, easy damage to the release film, and easy adhesive residue. It successfully achieves stable mass production of diffusion films with single-sided adhesive backing on all four sides. The entire process is integrated and continuous, with precise positioning, controllable die-cutting depth, minimal adhesive misalignment, no residue, and no damage. The optical transmittance and haze indicators are excellent, and the product qualification rate is significantly improved. At the same time, it simplifies the process, increases production capacity, reduces defect rates and production costs, transforming four-sided adhesive backing of diffusion films from a difficult-to-mass-produce process into a highly efficient, stable, and high-quality standardized operation, significantly enhancing the product's market competitiveness and meeting the stringent requirements of high-end backlight modules for diffusion film adhesive backing.

Description

Technical Field

[0001] This invention relates to the field of optical film technology, and in particular to a four-sided adhesive backing process for a diffusion film. Background Technology

[0002] In LCD backlight modules, the diffuser film is a key optical component, and the adhesive application process directly affects assembly accuracy and operational stability. Existing traditional processes can only apply adhesive to the two sides of the diffuser film in the same direction, failing to achieve four-sided adhesive application. To achieve four-sided adhesive application, double-sided adhesive must be used, which suffers from issues such as easy lateral misalignment of the adhesive and poor dimensional accuracy. Furthermore, traditional backing films are mostly made of a single PET material, lacking sufficient thickness and hardness, making them prone to deformation and damage during die-cutting. This results in adhesive residue, product scratches, low yield, and poor efficiency, making it difficult to meet the demands of high-precision, high-volume production. Therefore, a new process is urgently needed that can achieve single-sided adhesive application to the diffuser film on all four sides, ensuring precise positioning and stable production. Summary of the Invention

[0003] The purpose of this invention is to provide a four-sided adhesive process for diffusion films to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A four-sided adhesive process for a diffusion film includes:

[0006] The diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film are longitudinally cut to obtain strips, which are then pre-treated.

[0007] Using a double-layer silicone protective film as the bottom release film, the adhesive-free side of the single-sided adhesive roll is attached to the surface of the bottom release film. The single-sided adhesive roll is cut laterally using an asynchronous die-cutting method. At the same time, positioning holes are punched on the bottom release film and the single-sided adhesive roll.

[0008] Obtain the die-cut strip with positioning holes, remove the edge waste generated by the transverse cutting, use the positioning holes as positioning reference to attach the ends of the longitudinal and transverse adhesive strips to form a closed four-sided adhesive frame, and simultaneously peel off the release paper on the surface of the four-sided adhesive frame.

[0009] The pretreated diffusion film substrate is aligned and laminated with the four-sided adhesive frame along the positioning reference. The bottom release film is used as a support carrier. The laminated strip is die-cut as a whole to form the shape of the diffusion film and the outline of the four-sided adhesive in one step.

[0010] The composite strip after overall die-cutting is obtained, and the outer frame waste after overall die-cutting is removed by the waste removal mechanism. The formed four-sided adhesive diffusion film unit is retained, and a protective film is attached to the optical surface of the four-sided adhesive diffusion film unit.

[0011] Obtain the laminated continuous forming strip, cut the continuous forming strip into individual products according to the set size parameters, and conduct finished product inspection on the individual products. Based on the inspection results, reject defective products, and ship the qualified individual products after packaging.

[0012] Furthermore, the bottom release film has a double-layer composite structure, which is composed of a bottom silicone layer and a top release layer through hot-pressing and UV curing processes. The thickness of the bottom release film is 0.5-0.9mm; wherein, the thickness of the bottom silicone layer is 0.2-0.3mm, which is used to bond with the adhesive-free side of the single-sided adhesive roll, and the thickness of the top release layer is 0.4-0.5mm, which is used to provide rigid support during the die-cutting process.

[0013] Furthermore, the bottom silicone layer of the release film is coated with a low-tack silicone coating with a thickness of 5-10 μm. The release force of the low-tack silicone coating at room temperature is 50-200 mN / 25 mm, and when the temperature rises to 45-55℃, the release force drops to 30-80 mN / 25 mm.

[0014] Furthermore, the top release layer of the bottom release film is made of PET release substrate, the surface of which is coated with a silicone-based release agent, and the tensile strength of the top release layer is ≥180MPa, and the Shore hardness is 80-85D.

[0015] Furthermore, when the bottom release film is used as the supporting carrier, a high-temperature resistant buffer layer is provided between the surface of the bottom release film and the composite material strip, and the thickness of the high-temperature resistant buffer layer is 0.05-0.1mm.

[0016] Furthermore, the longitudinal slitting is based on the length direction of the entire roll of raw materials, including the diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film, and is cut along the width direction of the roll to slit the entire roll of raw materials into longitudinal adhesive strips that meet the target specifications.

[0017] Furthermore, the transverse cutting is based on the length direction of the single-sided adhesive strip adhered to the release film, and is cut along the width direction of the single-sided adhesive strip to cut the single-sided adhesive strip into transverse strips of a preset size.

[0018] Furthermore, the protective film is made of a composite material of polycarbonate and polysiloxane, with a thickness of 0.08-0.12mm. The surface of the protective film is coated with an oleophobic and hydrophobic coating. The protective film is flush with the edge of the diffusion film substrate and is used to protect the optical surface of the diffusion film substrate.

[0019] Furthermore, the finished product inspection items include product appearance inspection, dimensional accuracy inspection, glue position accuracy inspection, and adhesive performance inspection.

[0020] Furthermore, the die-cutting depth of the overall die-cutting is dynamically adjusted based on the superimposed thickness data of the bottom release film, single-sided adhesive film and diffusion film substrate, cutting off the single-sided adhesive film and diffusion film substrate.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention significantly improves the support strength and bonding stability of the base carrier by thickening the protective film and optimizing its double-layer composite structure. It effectively avoids the positional displacement of single-sided adhesive during die-cutting, bonding, and waste removal processes, solving the problem of the significant application limitations of traditional diffusion film adhesive technology, which can only perform adhesive treatment on both sides in the same direction. Based on the optimized base film structure, continuous production of single-sided adhesive on all four sides of the diffusion film can be directly completed, eliminating the dependence on double-sided adhesive, expanding the application scenarios of diffusion film products, and transforming four-sided adhesive diffusion film into a mature product that can be standardized and mass-produced, meeting the needs of high-end backlight modules for high-precision and high-stability adhesive structures.

[0023] 2. The asynchronous die-cutting, precise positioning hole alignment, and one-time die-cutting process design of this invention, combined with the stable support of a high-strength backing film, ensures product dimensional accuracy, adhesive placement accuracy, and appearance integrity throughout the entire production process. During die-cutting, the backing film possesses excellent resistance to deformation and breakage, effectively preventing scratches, indentations, and other defects on the optical surface of the diffusion film caused by die-cutting pressure. In the waste removal and bonding stages, the optimized structure of the backing film makes adhesive layer peeling smoother, with no adhesive residue or waste material adhering, ensuring a clean adhesive surface and stable and reliable bonding performance. This significantly improves overall product consistency, makes adhesive placement more precise, effectively reduces raw material waste, rework frequency, and after-sales quality risks, greatly improves product qualification rate and market trust, and provides stable and reliable process assurance for high-end optical film products.

[0024] 3. The integrated continuous operation mode of the present invention eliminates redundant steps such as multiple positioning, repeated adjustments, and manual corrections in traditional processes, greatly improving the automation level and smoothness of the production line. The optimized support film has good durability and structural stability, which can stably support continuous production of multiple processes for a long time, extend the service life of consumables, further reduce material and maintenance costs, significantly increase output per unit time, quickly respond to the demand of large-volume orders, and shorten the delivery cycle. Attached Figure Description

[0025] Figure 1 This is a flow chart of the four-sided adhesive backing process for the diffusion film of the present invention. Detailed Implementation

[0026] 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.

[0027] Please see Figure 1 The present invention provides the following technical solutions:

[0028] A four-sided adhesive process for a diffusion film includes:

[0029] The diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film are fed into the slitting device and longitudinally cut according to the target specifications. The slitting strips are then pre-treated, including leveling and dust removal, to remove surface impurities and stress, so that the strips remain flat and without warping.

[0030] A double-layer silicone protective film with a thickness of 0.7mm is used as the bottom release film. The adhesive-free side of the single-sided adhesive roll is attached to the surface of the bottom release film with the adhesive side facing up. The single-sided adhesive roll is cut laterally using an asynchronous die-cutting method. At the same time, positioning holes are punched on the bottom release film and the single-sided adhesive roll. The positioning holes serve as the reference for subsequent adhesive application, waste removal, and lamination, ensuring the accuracy of the lateral adhesive strip position.

[0031] Obtain the die-cut strip with positioning holes, remove the edge waste generated by transverse cutting through the waste removal device, use the positioning holes as positioning reference to attach the ends of the longitudinal and transverse adhesive strips to form a closed four-sided adhesive frame, and simultaneously peel off the release paper on the surface of the four-sided adhesive frame to keep the adhesive surface clean and the bonding performance stable, in preparation for lamination with the diffusion film.

[0032] The pretreated diffusion film substrate is aligned and laminated with the four-sided adhesive frame along the positioning reference, so that the diffusion film completely covers the adhesive frame and is evenly compacted; the bottom release film is used as a support carrier, and the laminated strip is die-cut as a whole to form the shape of the diffusion film and the outline of the four-sided adhesive in one step.

[0033] After obtaining the composite strip after overall die-cutting, the waste of the outer frame after overall die-cutting is removed by the waste removal mechanism, and the formed four-sided adhesive diffusion film unit is retained. A protective film is attached to the optical surface of the four-sided adhesive diffusion film unit. The protective film is made of polycarbonate and polysiloxane composite material with a thickness of 0.08-0.12mm. The surface of the protective film is coated with an oleophobic and hydrophobic coating and has a hardness of 4H or higher. The protective film is flush with the edge of the diffusion film substrate. After bonding, there are no bubbles or wrinkles. It is used to protect the optical surface of the diffusion film substrate, improve the scratch resistance and stain resistance of the optical surface, and extend the service life of the product.

[0034] After obtaining the laminated continuous forming strip, the continuous forming strip is cut into individual products according to the set size parameters. The individual products are then inspected, including product appearance inspection, dimensional accuracy inspection, glue position accuracy inspection, and bonding performance inspection. Based on the inspection results, defective products with appearance defects, dimensional deviations, glue position offsets, and substandard bonding performance are rejected. The qualified individual products are then packaged and shipped.

[0035] In this embodiment, the longitudinal cutting is based on the length direction of the roll of raw materials consisting of diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film, and is cut along the width direction of the roll to cut the entire roll of raw materials into longitudinal adhesive strips that meet the target specifications.

[0036] In this embodiment, the transverse cutting is based on the length direction of the single-sided adhesive strip adhered to the release film, and is performed along the width direction of the single-sided adhesive strip to cut the single-sided adhesive strip into transverse strips of a preset size.

[0037] In this embodiment, impurities and stress are removed through slitting pretreatment, and positioning holes are punched synchronously through asynchronous die-cutting to ensure that the position of the adhesive strip, product size, and adhesive position accuracy meet the standards, thereby improving product quality and stability. The waste removal and adhesive application process ensures that the adhesive surface is clean and the bonding performance is stable. A special protective film is used in the lamination process to enhance the scratch resistance and stain resistance of the optical surface and extend the product's service life. This effectively solves problems such as adhesive position deviation, insufficient dimensional accuracy, easy scratching of the optical surface, and unstable bonding performance in the production of diffusion film backing adhesive. It achieves efficient, precise, and stable production of four-sided backing adhesive for diffusion film. It realizes integrated and continuous operation from slitting, die-cutting, lamination to inspection and shipment, reduces process redundancy, improves production efficiency, and at the same time, rejects defective products through full-item inspection of finished products to ensure the pass rate of shipped products, reduce production costs, and enhance the product's market competitiveness.

[0038] In this embodiment, the bottom release film serves as the core support carrier for asynchronous die-cutting, lamination, and subsequent processes. Its structure, material, and performance directly affect the positioning accuracy of the adhesive strip, the adhesive layer peeling effect, and the overall product quality. The bottom release film has a double-layer composite structure, consisting of a bottom silicone layer and a top release layer, using a hot-press lamination and UV curing process. The hot-press lamination temperature is 80-90℃, the lamination pressure is 0.6-0.8MPa, the lamination time is 15-20s, the UV curing wavelength is 365nm, the curing time is 8-12s, and the curing degree is ≥95%. The thickness of the bottom release film is 0.5-0.9mm; the thickness of the bottom silicone layer is 0.2-0.3mm, used for bonding with the adhesive-free side of the single-sided adhesive roll, and the thickness of the top release layer is 0.4-0.5mm, used to provide rigid support during the die-cutting process, achieving stable bottom support and ensuring smooth subsequent adhesive layer peeling, avoiding adhesive residue.

[0039] In this embodiment, the hot-pressing and UV-curing composite processes ensure a tight bond between the layers of the release film, eliminating delamination and bubble defects. This also enhances the overall rigidity and dimensional stability of the release film, ensuring that it maintains flatness and structural integrity throughout the entire process, including asynchronous die-cutting, gradient compaction, and laser-mechanical composite die-cutting. This further guarantees the positioning accuracy of the adhesive strip and the absence of residual adhesive peeling. Furthermore, the composite release film has a bending resistance of ≥1000 times, a bending angle of 180°, and exhibits no cracks or delamination, making it suitable for continuous mass production.

[0040] In this embodiment, the bottom silicone layer of the release film is coated with a low-tack silicone coating with a thickness of 5-10 μm. The release force of the low-tack silicone coating at room temperature is 50-200 mN / 25 mm, and when the temperature rises to 45-55℃, the release force drops to 30-80 mN / 25 mm. This ensures stable bonding between the single-sided adhesive roll and the release film, and also enables residue-free peeling during subsequent waste removal and lamination processes, avoiding damage or contamination of the adhesive layer. It also prevents air bubbles from forming during bonding, which could affect product quality. The top release layer of the release film is made of PET release substrate, with a silicone-based release agent coated on its surface. The tensile strength of the top release layer is ≥180 MPa, and its Shore hardness is [not specified]. With a release liner thickness of 80-85D, it possesses excellent tensile and deformation resistance, can withstand the pressure during the overall die-cutting process, ensures precise and controllable die-cutting depth, and avoids waste residue or product scratches caused by damage to the release liner. This solves the technical defects of existing single-material release liners that are easily deformed and damaged. When the release liner is used as a support carrier, a high-temperature resistant buffer layer is set between the surface of the release liner and the composite strip. The thickness of the high-temperature resistant buffer layer is 0.05-0.1mm, and the material is polyimide. This effectively buffers the pressure during the die-cutting process, further preventing scratches and damage to the release liner during die-cutting, while preventing the heat generated during die-cutting from being conducted to the adhesive layer, which would lead to a decrease in the adhesive layer's bonding performance and ensure the product's bonding stability.

[0041] In this embodiment, the die-cutting depth of the overall die-cutting is dynamically adjusted based on the superimposed thickness data of the bottom release film, single-sided adhesive film, and diffusion film substrate. The superimposed thickness data of the bottom release film, single-sided adhesive film, and diffusion film substrate are collected in real time by a real-time thickness monitoring system, and the feed amount of the die-cutting head is dynamically adjusted so that the die-cutting depth accurately matches the total thickness of the single-sided adhesive film and diffusion film substrate. Only the adhesive layer and diffusion film substrate are precisely cut off without damaging the bottom release film body. After die-cutting, the surface of the bottom release film is free of scratches, damage, and adhesive residue, ensuring that the bottom release film can play its core role of support and positioning and release without residue in subsequent processes. At the same time, it extends the service life of the bottom release film and adapts to the needs of continuous die-cutting production.

[0042] To further verify the superiority of the process of this invention, specific embodiments and comparative examples were set up, and the performance of each product was tested and compared. The testing standards were uniformly based on the preset standards of this embodiment. The test items included product qualification rate, adhesive offset, adhesive residue, release film breakage rate, optical transmittance, and production efficiency, as detailed below:

[0043] Example 1

[0044] Using the diffusion film four-sided adhesive backing process described in this invention, the bottom release film has a double-layer composite structure. The hot-pressing composite temperature is 85℃, the composite pressure is 0.7MPa, and the composite time is 18s. The UV curing wavelength is 365nm and the curing time is 10s. The overall thickness of the bottom release film is 0.7mm, of which the bottom silicone layer is 0.25mm and the top release layer is 0.45mm. The coating thickness of the bottom silicone layer is 8μm. The release force at room temperature is 120mN / 25mm, and the tensile strength of the top release layer is 185MPa.

[0045] The high-temperature resistant buffer layer is 0.08mm thick and made of polyimide.

[0046] The overall die-cutting process utilizes a real-time thickness monitoring system, with a protective film thickness of 0.1mm.

[0047] The inspection employed a combination of automated testing and manual re-inspection to obtain the following results:

[0048] The product qualification rate is 99.92%, the glue position offset is ≤0.015mm, the glue residue is ≤0.8mg / 25mm², the bottom release film breakage rate is 0.02%, the optical transmittance is 93.2%, the haze is 1.5%, the production efficiency is 48,000 pieces / day, and there are no appearance defects such as bubbles or scratches.

[0049] Example 2

[0050] The key parameters are adjusted as follows, using the same four-sided adhesive process for the diffusion film as described in Example 1:

[0051] The hot-pressing temperature of the bottom release film is 80℃, the composite pressure is 0.6MPa, the composite time is 15s, the UV curing time is 8s, the overall thickness of the bottom release film is 0.5mm, of which the bottom silicone layer is 0.2mm, the top release layer is 0.3mm, the coating thickness of the bottom silicone layer is 5μm, the release force at room temperature is 50mN / 25mm, and the tensile strength of the top release layer is 180MPa.

[0052] The high-temperature resistant buffer layer is 0.05mm thick, and the protective film is 0.08mm thick.

[0053] Test results: Product qualification rate 99.85%, adhesive offset ≤0.02mm, adhesive residue ≤1.0mg / 25mm², release film breakage rate 0.03%, optical transmittance 92.1%, haze 1.8%, production efficiency 42,000 pieces / day, meeting the requirements for mass production.

[0054] Example 3

[0055] The key parameters are adjusted as follows, using the same four-sided adhesive process for the diffusion film as described in Example 1:

[0056] The hot-pressing temperature of the bottom release film is 90℃, the lamination pressure is 0.8MPa, the lamination time is 20s, the UV curing time is 12s, the overall thickness of the bottom release film is 0.9mm, the bottom silicone layer is 0.3mm, the top release layer is 0.6mm, the coating thickness of the bottom silicone layer is 10μm, the release force at room temperature is 200mN / 25mm, and the tensile strength of the top release layer is 190MPa.

[0057] The high-temperature resistant buffer layer is 0.1mm thick, and the protective film is 0.12mm thick.

[0058] Test results: Product qualification rate 99.90%, adhesive offset ≤0.01mm, adhesive residue ≤0.7mg / 25mm², release film breakage rate 0.01%, optical transmittance 93.5%, haze 1.2%, production efficiency 51,000 pieces / day, and product performance is optimal.

[0059] Comparative Example 1

[0060] The same process steps as in Example 1 were used, but the bottom release film structure was not optimized. A single PET material bottom film with a thickness of 0.7 mm was used. There was no double-layer composite structure, no hot-pressing and UV curing process was performed, and there was no low-tack silicone coating or high-temperature resistant buffer layer on the surface. The remaining parameters were the same as in Example 1.

[0061] Test results: Product qualification rate 88.5%, adhesive position offset 0.05-0.08mm, adhesive residue 3.5-5.2mg / 25mm², release film breakage rate 1.2%, optical transmittance 88.3%, haze 3.8%, production efficiency 23,000 pieces / day. Problems such as adhesive residue, release film breakage, and severe adhesive position offset exist, which cannot meet the needs of mass production.

[0062] In summary, Examples 1-3 employ the optimized diffusion film four-sided adhesive process of this invention, especially the structural optimization of the release film, dynamic adjustment of die-cutting depth, and precise control of each process. The product qualification rate, optical performance, and production efficiency are significantly better than those of the comparative examples. This effectively solves the technical defects of traditional processes, such as adhesive position deviation, adhesive residue, and damage to the release film, and fully verifies the superiority and practicality of the process of this invention.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A four-sided adhesive backing process for a diffusion film, characterized in that, include: The diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film are longitudinally cut to obtain strips, which are then pre-treated. Using a double-layer silicone protective film as the bottom release film, the adhesive-free side of the single-sided adhesive roll is attached to the surface of the bottom release film. The single-sided adhesive roll is cut laterally using an asynchronous die-cutting method. At the same time, positioning holes are punched on the bottom release film and the single-sided adhesive roll. Obtain the die-cut strip with positioning holes, remove the edge waste generated by the transverse cutting, use the positioning holes as positioning reference to attach the ends of the longitudinal and transverse adhesive strips to form a closed four-sided adhesive frame, and simultaneously peel off the release paper on the surface of the four-sided adhesive frame. The pretreated diffusion film substrate is aligned and laminated with the four-sided adhesive frame along the positioning reference. The bottom release film is used as a support carrier. The laminated strip is die-cut as a whole to form the shape of the diffusion film and the outline of the four-sided adhesive in one step. Obtain the composite strip after overall die-cutting, peel off the outer frame waste after overall die-cutting, retain the formed four-sided adhesive diffusion film unit, and attach a protective film to the optical surface of the four-sided adhesive diffusion film unit. Obtain the laminated continuous forming strip, cut the continuous forming strip into individual products according to the set size parameters, and conduct finished product inspection on the individual products. Based on the inspection results, reject defective products, and ship the qualified individual products after packaging.

2. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The bottom release film has a double-layer composite structure, which is composed of a bottom silicone layer and a top release layer through hot pressing and UV curing processes. The thickness of the bottom release film is 0.5-0.9mm. The bottom silicone layer has a thickness of 0.2-0.3mm and is used to bond with the adhesive-free side of the single-sided adhesive roll. The top release layer has a thickness of 0.4-0.5mm and is used to provide rigid support during the die-cutting process.

3. The four-sided adhesive process for a diffusion film as described in claim 2, characterized in that, The bottom silicone layer of the release film is coated with a low-tack silicone coating with a thickness of 5-10 μm. The release force of the low-tack silicone coating at room temperature is 50-200 mN / 25 mm, and when the temperature rises to 45-55℃, the release force drops to 30-80 mN / 25 mm.

4. The four-sided adhesive process for a diffusion film as described in claim 2, characterized in that, The top release layer of the bottom release film is made of PET release substrate, and the surface of the PET release substrate is coated with silicone-based release agent. The tensile strength of the top release layer is ≥180MPa and the Shore hardness is 80-85D.

5. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, When the bottom release film is used as the supporting carrier, a high-temperature resistant buffer layer is provided between the surface of the bottom release film and the composite material strip, and the thickness of the high-temperature resistant buffer layer is 0.05-0.1mm.

6. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The longitudinal slitting is based on the length of the roll of raw materials, including the diffusion film substrate, single-sided adhesive roll, and double-layer thickened silicone protective film, and is cut along the width of the roll to divide the entire roll of raw materials into longitudinal adhesive strips that meet the target specifications.

7. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The transverse cutting is based on the length direction of the single-sided adhesive strip adhered to the release film, and is carried out along the width direction of the single-sided adhesive strip to cut the single-sided adhesive strip into transverse strips of a preset size.

8. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The protective film is made of a composite material of polycarbonate and polysiloxane, with a thickness of 0.08-0.12mm. The surface of the protective film is coated with an oleophobic and hydrophobic coating. The protective film is flush with the edge of the diffusion film substrate and is used to protect the optical surface of the diffusion film substrate.

9. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The finished product testing items include product appearance inspection, dimensional accuracy inspection, glue position accuracy inspection, and adhesive performance inspection.

10. The four-sided adhesive process for a diffusion film as described in claim 1, characterized in that, The die-cutting depth of the overall die-cutting is dynamically adjusted based on the superimposed thickness data of the bottom release film, single-sided adhesive film and diffusion film substrate, cutting off the single-sided adhesive film and diffusion film substrate.

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