A multi-layer composite polarizing film irregular profile composite cutting method for display screens

Abstract

The present application relates to a kind of multilayer composite polarizing film profile compound cutting method for display screen, multilayer composite polarizing film is handled as a whole low temperature thermostat, and die cutting machine and die are continuously refrigerant cooling;Adopt three-stage blade edge composite die stamping layered cut multilayer structure, adjust punching pressure to complete profile rough cutting, three-stage blade edge parallel lamination, second stage blade edge is higher than first stage blade edge, and third stage blade edge is higher than second stage blade edge;Mark the edge local defect area after punching, use ultraviolet nanosecond laser spot trimming, spray low-temperature mixed gas;Vacuum adsorption removes cutting edge residue, and after second inspection by vision system, product is wound or sliced. By low temperature thermostat treatment, the energy storage modulus of pressure-sensitive adhesive is improved, so that punching is without overflow glue and without wire drawing;Three-stage blade edge is used to cut soft and hard layer step by step, to avoid film layer delamination, corner microcrack;Finally, local defect is fixed-point laser trimming, low-temperature mixed gas inhibits heat diffusion, and reduces laser heat-affected zone width.

Description

Technical Field

[0001] This invention relates to the field of polarizing film cutting technology, and more particularly to a method for composite cutting of multilayer composite polarizing films with irregular contours for display screens. Background Technology

[0002] With the upgrading of automotive intelligence, full-screen and curved screen structures are becoming increasingly common in automotive central control displays. The matching polarizing film requires processing complex irregular contours such as large-radius composite arcs, crescent-shaped avoidance notches, and sensor or camera openings. The polarizing film is a multi-layered composite structure, sequentially composed of a release film, pressure-sensitive adhesive layer, lower TAC layer, PVA polarizing layer, upper TAC layer, and surface hard coating. The pressure-sensitive adhesive exhibits strong viscoelasticity at room temperature, while the PVA polarizing layer is heat-sensitive. Existing cutting processes have significant drawbacks. Conventional single die-cutting uses a one-cut-through mode, where the soft and hard layers are subjected to asynchronous forces. During the die-cutting process, the pressure-sensitive adhesive creeps and overflows, producing excess adhesive and burrs. Delamination and micro-cracks are prone to occur at irregular corners, and dimensional tolerances are difficult to control within ±0.1mm. Pure laser integral cutting will produce a large heat-affected zone, which will damage the orientation of PVA molecules and cause yellowing and whitening optical defects at the edges. In addition, the processing efficiency is low and the production cost is high. Existing die-cutting and laser lamination processes simply combine two steps, resulting in defects such as excess glue, heat damage, and edge burrs, which cannot meet the requirements of automotive-grade mass production.

[0003] The above problems urgently need to be addressed. Summary of the Invention

[0004] This invention discloses a method for composite cutting of irregular contours of multilayer composite polarizing film for display screens, aiming to solve the technical problems existing in the prior art.

[0005] This invention employs the following technical solution: low-temperature constant-temperature treatment of the multilayer composite polarizing film, while continuously cooling the die-cutting machine worktable and the three-stage cutting edge composite mold with refrigerant; using the three-stage cutting edge composite mold to punch and cut the multilayer structure in the multilayer composite polarizing film, while simultaneously using step-feeding to dynamically adjust the punching pressure to complete the rough cutting of irregular contours, wherein the three-stage cutting edge composite mold includes three stages of cutting edges, which are parallel and fitted together, with the second stage cutting edge higher than the first stage cutting edge, and the third stage cutting edge higher than the second stage cutting edge; marking local defect areas on the edge after punching using a vision system, and using ultraviolet nanosecond laser to precisely trim only the marked areas, while simultaneously spraying a low-temperature mixed gas for thermal isolation during laser processing, wherein the local defect areas on the edge after punching are used to indicate protruding areas where the outer edge of the punched contour is not on the same plane; vacuum adsorption to remove residue from the cut edge, and after a second inspection by the vision system, the finished product is wound up or slit.

[0006] Optionally, the temperature control range of the multilayer composite polarizing film is -5℃ to 0℃, and the heat preservation time is 30 to 40 minutes; the cooling temperature of the die-cutting machine workbench and the three-stage cutting edge composite mold is maintained at 0℃ to 5℃.

[0007] Optionally, the difference between the height of the second-order cutting edge and the height of the first-order cutting edge is 0.8 to 1.2 times the thickness of the pressure-sensitive adhesive layer in the multilayer composite polarizing film; the difference between the height of the third-order cutting edge and the height of the second-order cutting edge is 10 to 20 micrometers.

[0008] Optionally, the fillet transition radius of the irregular corner of the second-order cutting edge is 0.05 mm larger than that of the irregular corner of the first-order cutting edge, wherein the fillet transition radius of the irregular corner is used to indicate the fillet radius at the irregular bending structure of the third-order cutting edge.

[0009] Optionally, the multilayer structure in the stamping and layering cutting of the multilayer composite polarizing film includes: a stamping speed ≤ 30 times / minute; and a stamping pressure increase of 0.2 MPa for every 10 micrometers increase in the total thickness of the multilayer composite polarizing film.

[0010] Optionally, the ultraviolet nanosecond laser point trimming method includes: the wavelength of the ultraviolet nanosecond laser is 355nm, and the laser focus of the ultraviolet nanosecond laser is used to align the interface between the PVA layer and the lower TAC layer in the multilayer composite polarizing film.

[0011] Optionally, the ultraviolet nanosecond laser-based point trimming method further includes setting the pulse width of the ultraviolet nanosecond laser to 10 ns, the repetition frequency to 30 kHz, the scanning speed to 200 mm / s, and the energy density to 0.8–1.2 J / cm². 2 .

[0012] Optionally, the use of a cryogenic mixed gas for thermal isolation in laser processing includes: a ring-shaped slit nozzle is circumferentially arranged on the ultraviolet nanosecond laser, and the distance between the outlet of the ring-shaped slit nozzle and the surface of the multilayer composite polarizing film is set between 1.5 mm and 2.5 mm; a vortex cooling tube is arranged inside the ring-shaped slit nozzle for spraying out a cooling mixed protective gas.

[0013] Optionally, the mixed protective gas is sulfur hexafluoride gas mixed with 0.1% to 0.5% nitrogen; the temperature range of the mixed protective gas is set to -15℃ to -5℃, and the injection flow rate is 10 to 20 L / min.

[0014] Optionally, vacuum adsorption to remove residue from the cut edge includes: using a vacuum nozzle equipped with an ion fan to adsorb particles from the cut edge; the negative pressure value of the vacuum nozzle is set to -0.06 to -0.08 MPa.

[0015] The technical solution adopted in this invention can achieve at least one of the following beneficial effects: In this embodiment of the invention, the energy storage modulus of the pressure-sensitive adhesive is improved by low-temperature isothermal treatment, so that there is no overflow or stringing during the punching process and the cut surface is flat. At the same time, a three-stage cutting edge is used to cut and isolate the punching stress of the soft and hard layers, avoiding film layer delamination and corner micro-cracks. The discontinuous cutting marks of the three-stage cutting edge facilitate the subsequent peeling of the release film. Finally, only local defects are laser trimmed, and low-temperature SF6 mixed gas is used to suppress heat diffusion, and the width of the laser heat-affected zone is compressed to less than 10 micrometers, protecting the optical performance of the PVA polarizing layer. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a flowchart of a multilayer composite polarizing film irregular contour composite cutting method for display screen in Embodiment 1 of the present invention; Figure 2 This is a flowchart of an optional composite cutting method for irregular contours of multilayer composite polarizing film for display screen in Embodiment 2 of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a magnetic connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0019] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] To address the problems existing in related technologies, this application provides a method for composite cutting of irregular contours of multilayer composite polarizing film for display screens.

[0021] Example 1 This embodiment provides a method for composite cutting of irregular contours of multilayer composite polarizing film for display screens, such as... Figure 1 As shown, Figure 1 This is a flowchart of a method for composite cutting of irregular contours of multilayer composite polarizing film for display screen according to Embodiment 1 of the present invention. The method includes: Step S102 involves a low-temperature constant-temperature treatment of the multilayer composite polarizing film, while the die-cutting machine worktable and the three-stage blade composite mold are continuously cooled by refrigerant. Optionally, the multilayer composite polarizing film consists of, in sequence, a release film (thickness 25μm to 50μm), a pressure-sensitive adhesive layer (thickness 15μm to 25μm), a lower TAC layer (thickness 40μm to 60μm), a PVA polarizing layer (thickness 20μm to 30μm), an upper TAC layer (thickness 40μm to 60μm), and a surface hard coating layer (thickness 5μm to 10μm).

[0022] Optionally, for multilayer composite polarizing films, a pre-cooling and shaping stabilization treatment, i.e., low-temperature isothermal treatment, is performed first. This low-temperature aging treatment alters the rheological properties of the pressure-sensitive adhesive, effectively addressing issues such as adhesive overflow and stringing. Specifically, the entire roll of multilayer composite polarizing film (sequentially release film, pressure-sensitive adhesive layer, lower TAC layer, PVA polarizing layer, upper TAC layer, and surface hard coating) is placed in a constant-temperature cooling chamber, with the temperature precisely controlled between -5℃ and 0℃, and held for 30 to 40 minutes (ensuring the pressure-sensitive adhesive is fully embrittled). Simultaneously, the die-cutting machine worktable and the three-stage cutting edge composite mold are cooled to 0℃ to 5℃ using circulating refrigerant, and this low-temperature state is maintained throughout the entire die-cutting process to prevent the temperature from rising after the polarizing film is removed from the cooling chamber, which could cause the pressure-sensitive adhesive to regain its stickiness and result in adhesive overflow. After this treatment, the storage modulus of pressure-sensitive adhesive can be increased by 3 to 5 times. The originally soft and viscous adhesive layer becomes similar to a brittle solid. It will not string or creep and overflow to both sides of the cut when punching, and the cut surface is neat and smooth.

[0023] In some preferred embodiments, the temperature control range of the multilayer composite polarizing film is -5℃ to 0℃, and the heat preservation time is 30 to 40 minutes; the cooling temperature of the die-cutting machine worktable and the three-stage cutting edge composite mold is maintained at 0℃ to 5℃.

[0024] Optionally, the entire roll of multi-layer composite polarizing film to be cut is placed in a constant temperature cooling box, set to -5℃ to 0℃, and kept at that temperature for 30 to 40 minutes to fully embrittle the pressure-sensitive adhesive layer and increase the energy storage modulus by 3 to 5 times. At the same time, the worktable of the die-cutting machine and the cutting edge of the three-stage cutting edge composite mold are cooled to 0℃ to 5℃ by circulating refrigerant and maintained at this temperature until the die-cutting is completed.

[0025] Optionally, by utilizing low temperature to alter the rheological properties of the pressure-sensitive adhesive, and based on the Williams-Landel-Ferry (WLF) equation, it is possible to achieve no adhesive overflow and no stringing during die-cutting. The derivation is as follows: WLF equation expression: Where η(T) is the viscosity of the pressure-sensitive adhesive at temperature T, η(Tg) is the viscosity at the glass transition temperature Tg, C1 is the characteristic constant of the first pressure-sensitive adhesive (C1=8.86), C2 is the characteristic constant of the second pressure-sensitive adhesive (C2=101.6), T is the processing temperature (-5℃~0℃), and Tg is the glass transition temperature of the pressure-sensitive adhesive (≤-30℃).

[0026] Alternatively, substituting T = -5℃ and Tg = -30℃, we can calculate η(T) / η(Tg)≈10 3 ~10 4 That is, the viscosity of the pressure-sensitive adhesive is 3 to 4 orders of magnitude higher than that at Tg when the temperature is -5℃ to 0℃, and the storage modulus is 3 to 5 times higher. The adhesive layer changes from a highly viscoelastic state to a brittle solid state. It exhibits brittle fracture during punching and will not creep, overflow, or string. The cut surface is neat. After returning to room temperature, the viscosity of the adhesive layer drops back to its original tackiness and does not affect subsequent bonding.

[0027] Step S104: A three-stage cutting edge composite mold is used to stamp and cut the multi-layer structure in the multi-layer composite polarizing film. At the same time, the step feeding dynamically adjusts the punching pressure to complete the rough cutting of the irregular contour. The three-stage cutting edge composite mold includes three cutting edges, which are parallel and attached. The second cutting edge is higher than the first cutting edge, and the third cutting edge is higher than the second cutting edge. Optionally, the three-stage cutting edge composite mold is an integrated structure that matches the irregular contour of the multi-layer composite polarizing film. The heights of the three cutting edges decrease sequentially, and their horizontal projection trajectories completely overlap. Specifically, the first-stage cutting edge (the highest, with a height of H1) penetrates the release film and pressure-sensitive adhesive layer, cutting the soft adhesive layer and release film first to avoid stretching of the adhesive layer when cutting the hard layer later; the second-stage cutting edge (slightly lower in height, with a height of H2 = H1 - Δh, where Δh = ... The cutting edge (0.8–1.2 times the thickness of the pressure-sensitive adhesive layer) is used to cut all functional hard layers, including the lower TAC layer, PVA polarizing layer, upper TAC layer, and surface hard coating. The second-stage cutting edge has a rounded transition radius at irregular corners (such as large-radius arcs or unequal-radius composite arcs), which is 0.05 mm larger than the theoretical corner radius of the first-stage cutting edge, preventing micro-cracks in the hard layers at sharp corners. The third-stage cutting edge (the lowest) only cuts into 1 / 2 to 2 / 3 of the release film thickness, forming discontinuous cuts without cutting the release film. This maintains the cutting accuracy and facilitates rapid peeling of the release film during subsequent bonding. A step-feeding system is used during cutting, with the cutting speed controlled at ≤30 times / minute. The cutting pressure is dynamically adjusted according to the total thickness of the multi-layer composite polarizing film; for every 10 μm increase in thickness, the pressure increases by 0.2 MPa, ensuring clean cuts without delamination or tearing.

[0028] In some preferred embodiments, the difference between the height of the second-order cutting edge and the height of the first-order cutting edge is 0.8 to 1.2 times the thickness of the pressure-sensitive adhesive layer in the multilayer composite polarizing film; the difference between the height of the third-order cutting edge and the height of the second-order cutting edge is 10 to 20 micrometers.

[0029] Optionally, the pre-cooled multilayer composite polarizing film is fed to the cold platform of the die-cutting machine in a step-by-step manner. After precise positioning, the die-cutting machine is started to punch, and the layer cutting is completed in one punching action: the first cutting edge first contacts and cuts the release film and pressure-sensitive adhesive layer, the second cutting edge then cuts the lower TAC layer, PVA polarizing layer, upper TAC layer and surface hard coating, and the third cutting edge simultaneously cuts into 1 / 2 to 2 / 3 of the thickness of the release film, forming discontinuous cuts; the punching speed is controlled at ≤30 times / minute, and the punching pressure is dynamically adjusted according to the total thickness of the multilayer composite polarizing film. For every 10μm increase in thickness, the pressure increases by 0.2MPa; after punching, the multilayer composite polarizing film is sent to the next station through the feeding mechanism, and the inner hole waste is discharged at the same time.

[0030] When a complete cut is made in one go, the hard layer (TAC, surface hard coating) and the soft layer (pressure-sensitive adhesive) are subjected to asynchronous stress, resulting in interlayer peeling stress and delamination. The third-order cutting edge achieves stress isolation through step-by-step cutting, as derived below: Interlayer peel stress τ satisfies: Where F is the punching and extrusion pressure, ΔE is the difference in elastic modulus between the hard layer and the soft layer, E1 is the elastic modulus of the hard layer (E≈3GPa for TAC layer), and E2 is the elastic modulus of the soft layer (E≈0.1MPa for pressure-sensitive adhesive at room temperature).

[0031] When ΔE is extremely large and τ is high, interlayer delamination is likely to occur. When the first-stage cutting edge cuts the soft layer (pressure-sensitive adhesive + release film), the soft layer is separated from the hard layer after being cut. When the second-stage cutting edge cuts the hard layer, the extrusion force F only acts on the hard layer, ΔE approaches 0, τ≈0, and interlayer delamination is completely eliminated. In some preferred embodiments, the fillet transition radius of the irregular corner of the second-order cutting edge is 0.05 mm larger than that of the irregular corner of the first-order cutting edge, wherein the fillet transition radius of the irregular corner is used to indicate the fillet radius at the irregular bending structure of the third-order cutting edge.

[0032] Optionally, a larger fillet radius is provided at the second-order cutting edge corner, and the stress concentration factor K satisfies: Where t is the total thickness of the hard layer and r is the radius of the corner fillet. When r increases by 0.05 mm, the K value decreases by more than 30%, thus avoiding the generation of microcracks at the sharp corners of the hard layer.

[0033] In some preferred embodiments, the multilayer structure in the stamping and layering cutting of the multilayer composite polarizing film includes: a stamping speed ≤ 30 times / minute; and a stamping pressure increase of 0.2 MPa for every 10 micrometers increase in the total thickness of the multilayer composite polarizing film.

[0034] Step S106: Mark the local defect area on the edge after punching using a vision system, and use ultraviolet nanosecond laser to trim the marked area only. At the same time, spray low temperature mixed gas for thermal isolation of laser processing. The local defect area on the edge after punching is used to indicate the protruding area where the outer edge of the punched contour is not on the same plane. Optionally, the ultraviolet nanosecond laser is only used to remove fibrous burrs and localized delamination from the punched edges, without participating in the overall contour cutting, thus ensuring accuracy and avoiding thermal damage. Specifically, the punched multilayer composite polarizing film (with a complete irregular contour and only minor defects at the edges) is positioned on the laser stage. A 355nm ultraviolet nanosecond laser is used, and an online vision inspection system (5μm / pixel resolution) marks defect areas with burr height >15μm. The laser only performs point-to-point scanning and trimming of the marked areas, rather than scanning the entire circle, significantly improving production efficiency. It should be noted that the vision system uses existing image recognition technology for recognizing protrusions.

[0035] Optionally, the pulse width of the ultraviolet nanosecond laser is set to 10 ns, the repetition rate to 30 kHz, the scanning speed to 200 mm / s, and the energy density to be controlled between 0.8 and 1.2 J / cm². 2 The laser focus is precisely aligned with the neutral layer (i.e., the interface between the PVA layer and the lower TAC layer) in the thickness direction of the polarizing film, prioritizing the removal of prominent defects caused by punching, without increasing the overall dimensions, ensuring that the finished product dimensions are dominated by the punching die and the accuracy is corrected by the laser. Meanwhile, an annular slit nozzle is set around the laser processing head. The outlet of the annular slit nozzle is 1.5mm to 2.5mm away from the surface of the polarizing film. It continuously sprays a low-temperature mixed gas (temperature -15℃ to -5℃, flow rate 10 to 20L / min) cooled by the vortex tube. This gas is a mixture of nitrogen and sulfur hexafluoride (SF6) with a volume fraction of 0.1% to 0.5%. Nitrogen is responsible for quickly removing the cutting heat, while sulfur hexafluoride (SF6), with its strong electronegativity, absorbs free electrons in the laser plasma, inhibiting heat diffusion and helping to remove slag. Under the dual effect, the width of the laser heat-affected zone is compressed to less than 10μm, which is much smaller than the 100μm of pure laser cutting. This effectively avoids the whitening and yellowing discoloration of the PVA polarizing layer due to thermal damage and does not affect the polarization optical performance.

[0036] In some preferred embodiments, the use of ultraviolet nanosecond laser for point trimming includes: the wavelength of the ultraviolet nanosecond laser is 355nm, and the laser focus of the ultraviolet nanosecond laser is used to align the interface between the PVA layer and the lower TAC layer in the multilayer composite polarizing film.

[0037] In some preferred embodiments, the use of ultraviolet nanosecond laser for targeted trimming further includes setting the pulse width of the ultraviolet nanosecond laser to 10 ns, the repetition frequency to 30 kHz, the scanning speed to 200 mm / s, and the energy density to 0.8–1.2 J / cm². 2 .

[0038] Optionally, the multilayer composite polarizing film marking the defect area is positioned on the laser stage, and the ultraviolet nanosecond laser parameters are adjusted as follows: pulse width 10 ns, repetition rate 30 kHz, scanning speed 200 mm / s, and energy density 0.8–1.2 J / cm². 2 The laser focus is aligned with the neutral layer (the interface between the PVA layer and the lower TAC layer) in the thickness direction of the multilayer composite polarizing film, and only the marked defect areas are scanned and trimmed.

[0039] In some preferred embodiments, the use of a cryogenic mixed gas for thermal isolation in laser processing includes: a ring-shaped slit nozzle is circumferentially arranged on the ultraviolet nanosecond laser, and the distance between the outlet of the ring-shaped slit nozzle and the surface of the multilayer composite polarizing film is set between 1.5 mm and 2.5 mm; a vortex cooling tube is arranged inside the ring-shaped slit nozzle to spray out the cooling mixed protective gas.

[0040] Optionally, during the operation of the ultraviolet nanosecond laser, heat conduction is suppressed by a cryogenic mixed gas. The heat Q generated by laser cutting is dissipated through convection of the cryogenic gas, and the heat conduction rate q satisfies: Where h is the convective heat transfer coefficient, A is the heat transfer area, Tlaser is the laser focal temperature, and Tgas is the mixed gas temperature (-15℃ to -5℃).

[0041] Substituting the parameters into the calculation, the q value is increased by 4 to 5 times, which can limit the temperature rise near the laser focus to below the glass transition temperature of the TAC layer (about 150°C), thus avoiding thermal damage to the PVA polarizing layer.

[0042] In some preferred embodiments, the mixed protective gas is a mixture of sulfur hexafluoride gas and 0.1% to 0.5% nitrogen gas; the temperature range of the mixed protective gas is set to -15°C to -5°C, and the injection flow rate is 10 to 20 L / min.

[0043] Optionally, during laser finishing, the annular slit nozzle continuously sprays a mixture of nitrogen and SF6 at -15℃ to -5℃, with a flow rate of 10 to 20 L / min. The nozzle outlet is 1.5 mm to 2.5 mm away from the surface of the polarizing film, which quickly removes the cutting heat, eliminates slag, and inhibits the diffusion of the heat-affected zone.

[0044] Optionally, when ejecting the mixed gas, plasma confinement is required. Sulfur hexafluoride (SF6) in the mixed gas has high electronegativity and can absorb free electrons (e) from the laser plasma. - The reaction formula is: This reaction can suppress plasma diffusion and reduce thermal radiation. At the same time, the high specific heat capacity of SF6 molecules can further absorb heat. Combined with high-speed airflow, the width of the heat-affected zone is compressed to less than 10 μm, which is much smaller than the 100 μm of pure laser cutting.

[0045] Step S108: Vacuum adsorption removes residue from the cut edges. After a second inspection by the vision system, the finished product is rolled up or slit.

[0046] Optionally, after laser finishing, an attached vacuum nozzle (negative pressure value -0.06 to -0.08 MPa) is used to remove residual fine particles and slag from the edges at close range, preventing particles from adhering and affecting the cleanliness of subsequent bonding. Then, an ion air gun is used to remove static electricity from the surface of the polarizing film to prevent static adsorption of particles. Finally, a full inspection is performed using an online visual inspection system to determine that the edges are free of burrs, carbonization, delamination, and excess glue, and that the dimensional tolerance is controlled within ±0.05 mm. After passing the inspection, the film is either wound up or separated into individual pieces to complete the entire cutting process.

[0047] Optionally, dimensional tolerances are primarily determined by the punching die and corrected using laser finishing. Precision control must meet the following requirements: Where ΔL is the total tolerance of the finished product, ΔL1 is the tolerance of the punching die (≤±0.03mm), and ΔL2 is the laser finishing deviation (≤±0.02mm). Substituting these values ​​into the calculation, we get ΔL≤±0.05mm, which meets the automotive-grade precision requirements. Simultaneously, low-temperature treatment can suppress the difference in thermal expansion between the layers of the polarizing film, reducing the difference in thermal expansion coefficients. This further improves dimensional stability.

[0048] In some preferred embodiments, vacuum adsorption to remove residue from the cut edge includes: using a vacuum nozzle equipped with an ion fan to adsorb particles from the cut edge; the negative pressure value of the vacuum nozzle is set to -0.06 to -0.08 MPa.

[0049] Optionally, an attached vacuum nozzle (negative pressure value -0.06 to -0.08 MPa) is used for negative pressure cleaning to remove fine particles and slag remaining on the edge of the polarizing film at close range; an ion air gun is used to blow away static electricity from the surface of the polarizing film to prevent static adsorption of particles; and then an online visual inspection system is used for full inspection to confirm that there are no burrs, carbonization, delamination, or excess glue on the edges, and that the dimensional tolerance is ≤ ±0.05 mm. After passing the inspection, the film is either wound up or separated into individual sheets to complete the cutting.

[0050] Example 2 This embodiment also provides an optional method for composite cutting of irregular contours of multilayer composite polarizing films for displays, such as... Figure 2 As shown, Figure 2 This is a flowchart of an optional composite cutting method for irregular contours of multilayer composite polarizing film for display screens according to Embodiment 2 of the present invention. The method includes: Step S1: Pre-cool the entire roll of multi-layer composite polarizing film in a constant temperature chamber of -5℃ to 0℃ for 30 to 40 minutes, while simultaneously cooling the die-cutting machine worktable and the cutting edge of the three-stage composite die to 0℃ to 5℃. Optionally, the entire roll of multilayer composite polarizing film is subjected to low-temperature aging treatment before punching, with the treatment temperature controlled between -5℃ and 0℃ and the treatment time ≥30 minutes; and during the punching process, the temperature of the cold platform of the die-cutting machine and the cutting edge of the punching die is maintained between 0℃ and 5℃ by circulating coolant until the punching is completed; this low-temperature treatment can change the rheological properties of the pressure-sensitive adhesive, increasing the storage modulus of the pressure-sensitive adhesive by 3 to 5 times, achieving no overflow or stringing during punching, which is different from conventional room temperature die-cutting or heated die-cutting processes.

[0051] Step S2: A three-stage cutting edge composite die is used for step-by-step punching. The punching speed is ≤30 times / minute. The punching pressure is dynamically adjusted according to the total thickness of the multilayer composite polarizing film. For every 10μm increase in thickness, the punching pressure increases by 0.2MPa. Optionally, the three-stage cutting edge composite mold is a three-stage cutting edge composite integrated structure, with the horizontal projection trajectories of the three cutting edges completely overlapping and their heights decreasing sequentially. Specific parameters meet the following requirements: The first cutting edge height H1 cuts through the release film and pressure-sensitive adhesive layer; the second cutting edge height H2 = H1 - Δh, where Δh = 0.8 to 1.2 times the thickness of the pressure-sensitive adhesive layer, is used to cut through the lower TAC layer, PVA polarizing layer, upper TAC layer and surface hard coating; the third cutting edge height H3 = H2 - (10 to 20 μm), cuts only 1 / 2 to 2 / 3 of the release film thickness, forming discontinuous cuts that facilitate peeling.

[0052] Optionally, the radius of the rounded transition at the irregular corner of the second-order cutting edge is 0.05 mm larger than the corner radius of the first-order cutting edge, in order to avoid microcracks at the sharp corners of the hard layer.

[0053] Step S3: After punching, the defect area with burr height > 15 μm is marked by scanning with an online visual inspection system (resolution 5 μm / pixel); Step S4: Laser point-finishing is performed on the marked defect area, and low-temperature mixed gas is sprayed simultaneously for auxiliary cooling. Optionally, laser trimming is used to remove fibrous burrs (height > 15 μm) and localized delamination from the punched edges, without participating in the overall irregular contour cutting; the laser scanning trajectory is offset inward by 0.02 mm to 0.05 mm relative to the punched contour, and the laser focus is precisely aligned with the neutral layer (the interface between the PVA layer and the lower TAC layer) in the polarizing film thickness direction; the laser uses a 355 nm ultraviolet nanosecond laser with the following parameters: pulse width 10 ns, repetition frequency 30 kHz, scanning speed 200 mm / s, and energy density 0.8–1.2 J / cm². 2 Before laser trimming, defect areas are marked using an online visual inspection system to achieve targeted trimming and improve production efficiency.

[0054] Step S5: Use an attached vacuum annular slit nozzle (negative pressure value -0.06 to -0.08 MPa) to remove edge particles, use an ion air gun to eliminate static electricity, and then perform a full inspection through an online visual inspection system. Optionally, an annular slit nozzle is provided around the laser processing head, with the distance between the nozzle outlet and the surface of the polarizing film being 1.5mm to 2.5mm. The gas ejected from the nozzle is a mixture of nitrogen and sulfur hexafluoride (SF6) with a volume fraction of 0.1% to 0.5%, with a gas temperature of -15℃ to -5℃ and a flow rate of 10 to 20 L / min. This mixture is ejected after being cooled by a vortex tube to suppress the diffusion of the laser heat-affected zone and remove slag. The sulfur hexafluoride (SF6) is used to absorb free electrons in the laser plasma and enhance the thermal isolation effect.

[0055] Step S6: After passing the test, rewind or separate individual sheets; The overall yield is more than 12% higher than that of simple die-cutting and more than 20% higher than that of simple laser cutting. The finished product dimensional tolerance is ≤ ±0.05mm, and there is no excess glue, delamination, or heat damage at the edges.

[0056] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for composite cutting of irregular contours of multilayer composite polarizing film for display screens, characterized in that, include: The multi-layer composite polarizing film is subjected to low-temperature constant temperature treatment, while the die-cutting machine worktable and the three-stage blade composite mold are continuously cooled by refrigerant. The three-stage cutting edge composite mold is used to stamp and cut the multi-layer structure in the multi-layer composite polarizing film. At the same time, the step feeding dynamically adjusts the punching pressure to complete the rough cutting of the irregular contour. The three-stage cutting edge composite mold includes three cutting edges, which are parallel and attached. The second cutting edge is higher than the first cutting edge, and the third cutting edge is higher than the second cutting edge. The local defect area on the edge after punching is marked by a vision system. Only the marked area is trimmed by ultraviolet nanosecond laser. At the same time, a low temperature mixed gas is sprayed for thermal isolation of the laser processing. The local defect area on the edge after punching is used to indicate the convex area where the outer edge of the punched contour is not on the same plane. Vacuum adsorption removes residue from the cut edges, and after a second inspection by a vision system, the finished product is either rolled up or slit.

2. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, The temperature control range of the multilayer composite polarizing film is -5℃ to 0℃, and the heat preservation time is 30 to 40 minutes; The cooling temperature of the die-cutting machine worktable and the three-stage cutting edge composite mold is maintained at 0℃~5℃.

3. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, The difference between the height of the second-order cutting edge and the height of the first-order cutting edge is 0.8 to 1.2 times the thickness of the pressure-sensitive adhesive layer in the multilayer composite polarizing film; The difference between the height of the third-order cutting edge and the height of the second-order cutting edge is 10 to 20 micrometers.

4. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, The fillet transition radius of the irregular corner of the second-order cutting edge is 0.05 mm larger than that of the irregular corner of the first-order cutting edge. The fillet transition radius of the irregular corner is used to indicate the fillet radius at the irregular curved structure of the third-order cutting edge.

5. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, The multilayer structure in the stamped, layered, and cut multilayer composite polarizing film includes: Stamping speed ≤ 30 times / minute; For every 10 micrometers increase in the total thickness of the multilayer composite polarizing film, the punching pressure increases by 0.2 MPa.

6. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, The use of ultraviolet nanosecond laser for precise edge trimming includes: The wavelength of the ultraviolet nanosecond laser is 355nm, and the laser focus of the ultraviolet nanosecond laser is used to align the interface between the PVA layer and the lower TAC layer in the multilayer composite polarizing film.

7. The method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 6, characterized in that, The use of ultraviolet nanosecond laser for pinpoint trimming also includes: The ultraviolet nanosecond laser has a pulse width of 10 ns, a repetition frequency of 30 kHz, a scanning speed of 200 mm / s, and an energy density of 0.8–1.2 J / cm². 2 .

8. A method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 6, characterized in that, The use of cryogenic mixed gas for thermal isolation in laser processing includes: The ultraviolet nanosecond laser is provided with an annular slit nozzle in the circumferential direction, and the distance between the outlet of the annular slit nozzle and the surface of the multilayer composite polarizing film is set between 1.5 mm and 2.5 mm. The annular slit nozzle is equipped with a vortex cooling pipe for spraying out a cooling mixed protective gas.

9. A method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 8, characterized in that, The mixed protective gas is sulfur hexafluoride gas mixed with 0.1% to 0.5% nitrogen; The temperature range of the mixed protective gas is set to -15℃ to -5℃, and the injection flow rate is 10 to 20 L / min.

10. A method for composite cutting of irregular contours of multilayer composite polarizing film for display screens according to claim 1, characterized in that, Vacuum adsorption for removing residue from cut edges includes: A vacuum nozzle equipped with an ion fan is used to adsorb particles from the cut edges; The negative pressure value of the vacuum nozzle is set to -0.06 to -0.08 MPa.

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