A side co-coating manufacturing process

Abstract

The application discloses a kind of edge co-coating preparation processes, optical function coating liquid is coated on support, then elastic resin coating liquid is coated in the edge of support conveying direction, the width of the co-coating area of elastic resin coating liquid and optical function coating liquid is set to 0.9-1.1cm, then dry film is prepared by heating, after removing support, edge co-coating film is obtained.The application uses the mode of edge co-coating, the dry film of elastic resin coating liquid is located in the edge of the dry film of optical function coating liquid, the co-coating area (i.e.the overlapping area) of the two forms splicing area, so that only part of the dry film of elastic resin coating liquid is cut off when cutting edge before stretching, cutting edge will not form cut, and film will not be broken when stretching, which is beneficial to batch production of film.

Description

Technical Field

[0001] This invention relates to an edge co-coating preparation process, specifically an edge co-coating preparation process for preparing optical compensation films, belonging to the field of optical thin film preparation technology. Background Technology

[0002] Optical compensation films are typically manufactured using extrusion. Resin is injected into an extruder, heated and melted, then discharged through a T-die. After passing through casting rollers, it is stretched in both length and width directions to obtain a biaxially oriented film. However, extrusion suffers from drawbacks such as high equipment costs, complex processes, and difficulty in removing extruded air bubbles. In recent years, a coating method has emerged for manufacturing optical compensation films. Specifically, polymer resin powder or granules are dissolved in an organic solvent to create a resin coating solution. This solution is then uniformly coated onto a support using a slot coating method. After baking and peeling off the support, a resin film is obtained, which is then biaxially stretched to produce the optical compensation film. However, during slot coating, the resin film often exhibits uneven thickness and uneven edge finishing at the edges. Therefore, edge trimming is necessary before stretching. But due to the brittleness of the resin film, cuts are easily formed during trimming, leading to film breakage during stretching and affecting the quality of the final optical compensation film.

[0003] In the prior art, invention patent CN106415340A discloses a method for fabricating a phase retardation film. First, a resin solution is coated onto a support film. Then, the resin solution is dried by heating, forming a laminated body with the coating tightly bonded to the support film. This laminate is then stretched in at least one direction during a stretching process, imparting optical anisotropy to the coating. Finally, the support is peeled off from the stretched laminate to obtain the phase retardation film. The coating method used in this method is not limited to various techniques such as blade coating, roller coating, gravure coating, reverse coating, spray coating, and wire rod coating. The appearance properties of the film can be improved by adding additives such as leveling agents and degradation inhibitors to the coating, setting the film thickness, and controlling the drying and heating temperature. Although stretching can be performed without edge trimming, the method still suffers from operational difficulties and poor stability.

[0004] The invention patent with publication number TW202237377A discloses a method for manufacturing an obliquely stretched film. This method can solve the problem of preventing the film from breaking during and after the trimming process. Specifically, during the oblique stretching process of the film, a pair of grippers hold both ends of the film in the width direction. One gripper moves relatively first while the other gripper moves relatively later to transport the film and stretch the film in the oblique direction in the width direction. This method stretches the film obliquely and then trims it to give it excellent cut surface quality.

[0005] As discussed above, in the preparation of optical films, to improve the appearance of the coated resin film and address the tendency for cracking during edge trimming, adjustments are typically made to the pre-trimming film-forming processes (including coating solution, drying, or stretching). However, these methods often place higher demands on the precise control of the process, increasing the difficulty of film production and resulting in poor product quality stability. Therefore, to solve the edge trimming problem inherent in current slot coating methods, and while meeting the requirements for efficient and high-quality industrial production of films, a simple and easily implemented industrial production method is essential. Summary of the Invention

[0006] The purpose of this invention is to provide an edge co-coating preparation process, which involves sequentially coating an optical functional coating liquid and an elastic resin coating liquid onto a support body, and then baking it to obtain a dry film. The dry film of the elastic resin coating liquid is located on both sides of the edge of the dry film of the optical functional coating liquid, and the co-coated area (i.e., the overlapping area) of the two forms a splicing area. This allows only a portion of the dry film of the elastic resin coating liquid to be cut off when the edge is trimmed before stretching, without forming a cut. The film will not break during stretching, which is beneficial for the mass production of the film.

[0007] The present invention is achieved through the following technical solution: an edge co-coating preparation process, wherein an optical functional coating liquid is coated on a support, and an elastic resin coating liquid is coated on the edge of the support in the transport direction, such that the width of the co-coated area of ​​the elastic resin coating liquid and the optical functional coating liquid is set to 0.9-1.1 cm, and then a dry film is obtained by heating. After removing the support, the edge co-coated film is obtained.

[0008] The optical functional coating liquid includes an optical compensation film resin coating liquid, and the elastic resin coating liquid includes an optical compensation film resin coating liquid and organic elastic particles.

[0009] The optical compensation film resin coating liquid contains at least a compensation film resin, a leveling agent, and an organic solvent.

[0010] The resin used for the compensation membrane includes one or more of the following: (meth)acrylic resin, polycarbonate resin, cycloolefin resin, cellulose resin, polyester resin, polyester carbonate resin, polyvinyl alcohol acetal resin, olefin resin, and polyurethane resin.

[0011] The organic elastic particles include one or more of the following: ultra-high molecular weight polyethylene particles, polypropylene particles, polyimide resin particles, acrylonitrile-butadiene-styrene copolymer resin particles, and polyester resin particles with 8 or more carbon atoms.

[0012] The organic elastic particles account for 1 to 5 w / w of the elastic resin coating liquid.

[0013] The solid content of the elastic resin coating liquid is 10-20%.

[0014] The coating methods for the optical functional coating liquid or elastic resin coating liquid include slot coating, roller coating, doctor blade coating, reverse coating, gravure coating, spray coating, air knife coating, or wire bar coating.

[0015] The heating includes pre-baking and calcination after pre-baking. The pre-baking temperature is set to 50-100℃ and the time is set to 15s-10min. The calcination temperature is set to 100-200℃ and the time is set to 5-200min.

[0016] The thickness of the film in the co-coated area on the edge co-coated film is 20-50 μm.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] (1) The present invention is proposed to solve the problems of easy formation of cuts when the film is cut and easy to break the film when stretched after the cut edge. The essence of the invention is to apply another layer of elastic resin coating on the edge of the support with optical functional coating layer, so that the elastic resin coating layer covers the edge of the optical functional coating layer. The co-coated area of ​​the two is the splicing area. When the edge-coated film is cut, only part of the elastic resin coating layer is cut off, and no cut is formed. After the film is cut, it will not break after entering the stretching process, thus affecting the optical performance of the film and ensuring the quality of the finished product.

[0019] (2) When the film is trimmed, the present invention only cuts off part of the elastic resin coating layer and retains part of the co-coated area. By limiting the width of the co-coated area, it is easy to seamlessly connect the optical functional coating layer and the elastic resin coating layer, so as to facilitate the subsequent peeling and stretching process.

[0020] (3) The present invention can realize the continuous coating of optical functional coating liquid and elastic resin coating liquid during the transport of the support body. The coating method can adopt known slit coating, roller coating and other devices. The coating device of elastic resin coating liquid can be set downstream of the optical functional coating liquid coating device. It only needs to be improved on the existing device. The structure is simple and the cost is low.

[0021] (4) The method of the present invention only requires adjustment or control of the coating device to obtain the edge co-coating layer with the required thickness or coating width, that is, the coating structure formed by the co-coating area. It does not limit the requirements of the stretching process and drying process in the film preparation process, and can be operated according to the original process. The operation is simple and easy to control.

[0022] In summary, this invention provides a preparation process that can directly change the nicks that appear when cutting the edge of an optical thin film and the easily broken film during stretching by coating. The preparation process is simple, greatly reduces equipment investment costs and improves product yield, and can realize mass production of products. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the edge co-coated thin film of the present invention.

[0024] Figure 2 This is a top view of the coating apparatus of the present invention.

[0025] Figure 3 This is a schematic diagram of the slit coating die head of the present invention.

[0026] Figure 4 This is a photograph of the cut edge after the film was trimmed.

[0027] Where A is the width of the optical compensation film, B is the width of the edge coating, and C is the width of the co-coated area.

[0028] 1—Support body, 2—Slit coating die head, 3—Edge coating die head, 4—Front clamping block, 5—Rear clamping block, 6—Gap shim, 7—Storage bin, 8—Inlet, 9—Lip. Detailed Implementation

[0029] The invention's objective, technical solution, and beneficial effects will be further explained in detail below.

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the claimed invention. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] This invention aims to provide a method for preparing an optical compensation film through edge co-coating. The optical compensation film corrects the phase difference generated by liquid crystals at various viewing angles in different display modes (TN / STN / TFT (VA / IPS / OCB)). In short, it compensates for the symmetry of the birefringence of liquid crystal molecules. Based on their functional purpose, they can be roughly divided into phase difference films that simply change the phase, chromatic aberration compensation films, and viewing angle widening films. Therefore, the use of optical compensation films can reduce light leakage in the dark state of liquid crystal displays and significantly improve image contrast and color within a certain viewing angle, while also overcoming some grayscale inversion problems.

[0032] In existing methods for preparing optical compensation films, the dried film needs to be trimmed before stretching. This trimming process easily results in cuts, and stretching can lead to film breakage, affecting the product yield. While improvements to the coating solution, drying process, or stretching process can appropriately enhance the film's optical properties and the quality of its cut surface, a simpler method is desired that, without altering existing compensation film manufacturing processes, addresses the impact of trimming and is suitable for mass production, better meeting the demands of large-scale, high-quality manufacturing.

[0033] The technical solution of the present invention can be summarized as follows:

[0034] An optical functional coating liquid is applied to the support body 1 along the conveying direction of the support body 1. The optical functional coating liquid includes an optical compensation film resin coating liquid or a resin coating liquid of other optical performance films. When multiple resin coating liquids are used for coating, they can be coated separately and a laminate with corresponding optical performance is formed on the support body 1.

[0035] When only optical compensation film resin is used as the optical functional coating liquid, a slit coating device can be used to coat the support 1, and then an elastic resin coating liquid can be coated on the edge of the support 1 in the transport direction, so that the elastic resin coating liquid and the optical functional coating liquid form a co-coated area on the support 1. After heating, a dry film is obtained. After peeling off the support 1, the edge co-coated film is obtained.

[0036] Optical compensation film resin coating

[0037] Optical compensation film resin coating is obtained by fully dissolving a certain amount of compensation film resin in an organic solvent, and fluorine-based or polysiloxane-based leveling agents may also be added to it.

[0038] Specifically, the resin used for optical compensation films can be any suitable material, as long as it meets the requirements of the environment in which it is used. Specific examples include: (meth)acrylic resins, polycarbonate resins, cycloolefin resins, cellulose resins, polyester resins, polyester carbonate resins, polyvinyl alcohol acetal resins, olefin resins, polyurethane resins, etc.

[0039] Specific examples of (meth)acrylic resins include polymethyl methacrylate, poly(meth)acrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylate copolymer, methyl methacrylate-acrylate-(meth)acrylic acid copolymer, and (meth)acrylate-styrene copolymer (MS resin). Preferably, methyl methacrylate contains 4 to 8 carbon atoms of acrylic acid.

[0040] Examples of the aforementioned cyclic olefin resins include: ring-opening polymerization of norbornene monomer and comonomer followed by hydrogenation. Specific examples of norbornene monomers include: bicyclo[2.2.1]hept-2-ene, tricyclo[4,3,0,12,5]-3-decene, tricyclo[4,4,0,12,5]-3-undecene, 7-methyltricyclo[4,4,0,12,5]-3-undecene, 5-methylbicyclo[2,2,1]hept-2-ene, 1-methylbicyclo[2,2,1]hept-2-ene, 7-methylbicyclo[2,2,1]hept-2-ene, 5-ethylbicyclo[2,2,1]hept-2-ene, etc. One or more monomers and comonomers can be cyclobutene, cyclopentene, cyclooctene, dicyclopentadiene, etc.

[0041] Any suitable polycarbonate resin can be used as the aforementioned polycarbonate resin. For example, a polycarbonate resin containing structural units derived from dihydroxy compounds is preferred. Specific examples of dihydroxy compounds include: 9,9-bis(4-hydroxyphenyl)fluorene, bisphenol fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-ethylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-propylphenyl)fluorene, 9,9-bis(4-hydroxy-3-isopropylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-sec-butylphenyl)fluorene, etc. In addition to structural units derived from the aforementioned dihydroxy compounds, polycarbonate resins may also contain structural units derived from dihydroxy compounds such as isosorbide, isodimannol, iso-idultitol, spirodiol, dioxanediol, diethylene glycol, triethylene glycol, polyethylene glycol, and bisphenols.

[0042] Specifically, the organic solvents that dissolve the above-mentioned optical compensation film resin coating liquid can be listed as follows: N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-isopropyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate, etc. These organic solvents can be used alone or in combination of two or more. Based on 100 parts by weight of resin, the amount of organic solvent used is 400 to 1000 parts by weight, more preferably 500 to 600 parts by weight. If the amount of organic solvent exceeds 1000 parts, the mechanical strength of the resulting compensation film will decrease. When the amount of organic solvent is less than 400 parts, the viscosity of the compensation film coating solution will be too high, and the film-forming performance will be poor.

[0043] In this invention, the use of a leveling agent effectively prevents oxygen from hindering the curing of the optical compensation film resin coating during application and drying, and also imparts scratch resistance to the coating surface. Based on 100 parts by weight of the resin component, the leveling agent content is preferably 0.005 to 20 parts by weight, more preferably 0.01 to 10 parts by weight, and even more preferably 0.01 to 3 parts by weight. It should be noted that two or more leveling agents can be used in combination.

[0044] Elastic resin coating

[0045] The elastic resin coating liquid contains at least the aforementioned optical compensation film resin coating liquid and organic elastic particles. The optical compensation film resin coating liquid can correspond to the optical compensation film resin coating liquid coated on the support 1. The use of organic elastic particles is to improve the elasticity and toughness of the edge film formed by edge coating. 1-5 w / w% of the amount of elastic resin coating liquid can be added to the elastic resin coating liquid. Specific examples of organic elastic particles include plastic beads, specifically including one or more of ultra-high molecular weight polyethylene particles, polypropylene particles, polyimide resin particles, acrylonitrile-butadiene-styrene copolymer resin particles, and polyester resin particles with 8 or more carbon atoms. In preparing the elastic resin coating liquid, the same optical compensation film resin and organic elastic particles are fully dissolved in a corresponding organic solvent. The resulting elastic resin coating liquid has a solid content of 10-20%.

[0046] Support body

[0047] The support 1 is a flexible substrate, typically made of transparent synthetic resins such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethersulfone, polyamide, polyimide, polymethyl methacrylate, and polycarbonate. Considering cost factors, polyethylene terephthalate is preferred.

[0048] Coating

[0049] In addition to slot coating, optical compensation film resin coatings and elastic resin coatings can also be applied using roller coating, doctor blade coating, reverse coating, gravure coating, spray coating, air knife coating, or wire rod coating.

[0050] Specifically, when using slit coating, firstly, the optical compensation film resin liquid is injected into the slit coating cavity, and then coated onto the support 1 through the slit coating die 2 to form a wet compensation film. An edge coating die 3 is then positioned downstream of the support 1 in the transport direction, approximately 10-15 cm from the slit coating die. The edge coating die 3 can be selected according to the production line requirements, ensuring that the elastic resin liquid is coated onto the edge of the wet compensation film. It should be noted that this edge refers to the edge in the transport direction of the wet compensation film.

[0051] After edge co-coating, the width of the co-coated area between the elastic resin coating and the wet film of the compensation film is 0.9–1.1 cm. (See [reference needed]). Figure 1 As shown in the shaded area, the wet film thickness can be adjusted by changing the settings of the slot coating die 2 or the edge coating die 3.

[0052] heating

[0053] The heating temperature of the coating is selected appropriately according to the type of organic solvent used, preferably by performing two stages: pre-baking and calcination. The pre-baking temperature is set to 50-100℃ for 15s-10min; the calcination temperature is set to 100-200℃ for 5-200min.

[0054] In one specific embodiment, the pre-baking temperature can be set to 60–80°C for 30–50 minutes; the calcination temperature can be set to 120–150°C for 10–100 minutes. Once the organic solvent in the coating has evaporated to a content below 2%, the film is cooled at a temperature controlled at 60–100°C. The resulting dry film has a thickness of 0.001–1 μm, or further, a thickness of 0.005–0.5 μm.

[0055] The following examples illustrate specific implementations of the present invention. Of course, the scope of protection of the present invention is not limited to the following examples.

[0056] Example 1: Coating Apparatus

[0057] As can be seen from the above-described edge co-coating process, two sets of coating dies are used on the support 1 for coating. The coating die can be selected according to the coating requirements or the requirements of the resin coating liquid, such as the slot coating method selected in this embodiment. See details. Figure 2 As shown, a slit coating die 2 is installed above the transport path of the support body 1. This die applies the optical compensation film resin solution to the support body 1 during transport. An edge coating die 3 is installed 15cm away from the slit coating die 3, also using the slit coating method. During the transport of the support body 1, an elastic resin solution is applied to the edge of the support body 1. The co-coated area of ​​the elastic resin solution and the optical functional solution forms a joint area, as shown... Figure 1 The shaded area shown.

[0058] Specifically, the structures of the slit coating die 2 and the edge coating die 3 used in this embodiment are as follows: Figure 3 As shown, the system includes a front clamping block 4, a rear clamping block 5, and a gap gasket 6. The rear clamping block 5 has a storage bin 7 and a feed inlet 8 connecting to the storage bin 7. The front clamping block 4 and the rear clamping block 5 are fixed together by a matching positioning bolt assembly. The gap gasket 6 is fixed between the front clamping block 4 and the rear clamping block 5 and has a flow channel. One end of the flow channel connects to the storage bin 7, and the other end connects to the lip 9 formed by the fixing of the front clamping block 4 and the rear clamping block 5. The function of the storage bin 7 is to regulate the pressure of the lip 9 before the coating liquid is extruded and to reduce pressure fluctuations during transport. The feed inlet 8 is used to connect to the feed pipe, and different connection methods can be designed according to specific production line requirements, making it highly practical.

[0059] Example 2: Edge Co-coating Process

[0060] Using PET film as support 1, and employing the coating apparatus of Example 1, an optical compensation film resin coating liquid is applied to the PET film, followed by an elastic resin coating liquid. The positions of the lips 9 of the slit coating die and the edge coating die 3 are adjusted to form a co-coated area between the elastic resin coating liquid and the optical functional coating liquid. The coated PET film is then pre-baked at 50–100°C for 15–10 minutes, and then calcined at 100–200°C for 5–200 minutes to obtain a dry film. After cooling, the PET film is peeled off to obtain the edge co-coated film.

[0061] Specifically, the optical compensation film resin coating solution used in this embodiment is prepared by adding 100 parts of polymethyl methacrylate (PMMA) to 800 parts of N-methyl-2-pyrrolidone, stirring at high speed until fully dissolved, and then adding 5 parts of a fluorinated leveling agent. The elastic resin coating solution is prepared by adding 3.5 w / w% of polyimide resin particles to the same optical compensation film resin coating solution to obtain a coating solution with a solid content of 20%.

[0062] Furthermore, the conveying speed of the PET film is controlled at 5 m / min. On the slit coating die head, the thickness of the gap shim 6 is controlled at 250 μm, the gap at the flow channel is controlled at 80 μm, the pump speed at 2500 rpm, and the cavity pressure at 0.20 MPa. On the edge coating die head 3, the thickness of the gap shim 6 is controlled at 200 μm, the gap at the flow channel is controlled at 50 μm, the pump speed at 250 rpm, and the cavity pressure at 0.20 MPa.

[0063] The resulting edge co-coated film satisfies the following conditions: the thickness of the optical compensation film is 45 μm, the thickness of the film in the co-coated area is 50 μm, and the width of the co-coated area is 1.1 cm.

[0064] Example 3: Edge Co-coating Process

[0065] The only difference between this embodiment and Embodiment 2 is the selection of the resin coating liquid and the control parameters of the coating die.

[0066] Specifically, in this embodiment, the optical compensation film resin coating solution is prepared by adding 100 parts of polymethyl methacrylate (PMMA) to 550 parts of N,N-dimethylformamide, stirring at high speed until fully dissolved, and then adding 3 parts of a polysiloxane leveling agent. The elastic resin coating solution is prepared by adding 1.0 w / w% of polyimide resin particles to the same optical compensation film resin coating solution to obtain a coating solution with a solid content of 14%.

[0067] Furthermore, the conveying speed of the PET film is controlled at 5 m / min. On the slit coating die, the thickness of the gap shim 6 is controlled at 300 μm, the gap at the flow channel is controlled at 100 μm, the pump speed at 3000 rpm, and the cavity pressure at 0.25 MPa. On the edge coating die 3, the thickness of the gap shim 6 is controlled at 100 μm, the gap at the flow channel is controlled at 50 μm, the pump speed at 200 rpm, and the cavity pressure at 0.15 MPa.

[0068] The resulting edge co-coated film satisfies the following conditions: the thickness of the optical compensation film is 40 μm, the thickness of the film in the co-coated region is 47 μm, and the width of the co-coated region is 0.9 cm.

[0069] Example 4: Edge Co-coating Process

[0070] The only difference between this embodiment and Embodiment 2 is the selection of the resin coating liquid and the control parameters of the coating die.

[0071] Specifically, in this embodiment, the optical compensation film resin coating solution is prepared by adding 100 parts of polymethyl methacrylate (PMMA) to 600 parts of N,N-dimethylacetamide, stirring at high speed until fully dissolved, and then adding 3 parts of a fluorinated leveling agent. The elastic resin coating solution is prepared by adding 2.5 w / w% of polyethylene particles to the same optical compensation film resin coating solution to obtain a coating solution with a solid content of 17%.

[0072] Furthermore, in this embodiment, the conveying speed of the PET film is controlled at 5 m / min. On the slit coating die head, the thickness of the gap shim 6 is controlled to be 300 μm, the gap at the flow channel is controlled to be 60 μm, the pump speed is controlled to be 3000 rpm, and the cavity pressure is controlled to be 0.25 MPa. On the edge coating die head 3, the thickness of the gap shim 6 is controlled to be 180 μm, the gap at the flow channel is controlled to be 60 μm, the pump speed is controlled to be 300 rpm, and the cavity pressure is controlled to be 0.25 MPa.

[0073] The resulting edge co-coated film satisfies the following conditions: the thickness of the optical compensation film is 39 μm, the thickness of the film in the co-coated region is 45 μm, and the width of the co-coated region is 1.0 cm.

[0074] Example 5: Edge Co-coating Process

[0075] The only difference between this embodiment and Embodiment 2 is the selection of the resin coating liquid and the control parameters of the coating die.

[0076] Specifically, in this embodiment, the optical compensation film resin coating solution is prepared by adding 100 parts of polymethyl methacrylate (PMMA) to 500 parts of N-methyl-2-pyrrolidone, stirring at high speed until fully dissolved, and then adding 0.5 parts of a polysiloxane leveling agent. The elastic resin coating solution is prepared by adding 3.0 w / w% of acrylonitrile-butadiene-styrene copolymer resin particles to the same optical compensation film resin coating solution to obtain a coating solution with a solid content of 18.8%.

[0077] Furthermore, in this embodiment, the conveying speed of the PET film is controlled at 5 m / min. On the slit coating die head, the thickness of the gap shim 6 is controlled to be 220 μm, the gap at the flow channel is controlled to be 70 μm, the pump speed is controlled to be 2500 rpm, and the cavity pressure is controlled to be 0.20 MPa. On the edge coating die head 3, the thickness of the gap shim 6 is controlled to be 100 μm, the gap at the flow channel is controlled to be 70 μm, the pump speed is controlled to be 300 rpm, and the cavity pressure is controlled to be 0.20 MPa.

[0078] The resulting edge co-coated film satisfies the following conditions: the thickness of the optical compensation film is 32 μm, the thickness of the co-coated area is 36 μm, and the width of the co-coated area is 0.9 cm.

[0079] Example 6: Edge Co-coating Process

[0080] The only difference between this embodiment and Embodiment 2 is the selection of the resin coating liquid and the control parameters of the coating die.

[0081] Specifically, in this embodiment, the optical compensation film resin coating solution is prepared by adding 100 parts of polymethyl methacrylate (PMMA) to 600 parts of N-methyl-2-pyrrolidone, stirring at high speed until fully dissolved, and then adding 2 parts of a fluorinated leveling agent. The elastic resin coating solution is prepared by adding 5 w / w% of polypropylene particles to the same optical compensation film resin coating solution to obtain a coating solution with a solid content of 23%.

[0082] Furthermore, in this embodiment, the conveying speed of the PET film is controlled at 5 m / min. On the slit coating die head, the thickness of the gap shim 6 is controlled to be 240 μm, the gap at the flow channel is controlled to be 90 μm, the pump speed is controlled to be 2650 rpm, and the cavity pressure is controlled to be 0.23 MPa. On the edge coating die head 3, the thickness of the gap shim 6 is controlled to be 200 μm, the gap at the flow channel is controlled to be 65 μm, the pump speed is controlled to be 225 rpm, and the cavity pressure is controlled to be 0.18 MPa.

[0083] The resulting edge co-coated film satisfies the following conditions: the thickness of the optical compensation film is 36 μm, the thickness of the film in the co-coated region is 44 μm, and the width of the co-coated region is 1.0 cm.

[0084] Comparative Example 1:

[0085] The only difference between this comparative example and Example 2 is the resin solution used for edge co-coating.

[0086] Specifically, in this comparative example, no organic elastic particles were added to the resin coating liquid used for edge co-coating. Only an optical compensation resin coating liquid with the same composition was used. The PET film conveying speed, coating device, control parameters of slit coating die 2, pre-drying and calcination conditions involved in the process were the same, but the control parameters of the edge coating die 3 were slightly different.

[0087] Specifically, the thickness (shim) of the gap shim 6 on the edge coating die 3 is 95um, the gap (GAP) at the flow channel is 55um, the pump speed is 200rpm, and the cavity pressure is 0.18MPa.

[0088] The resulting film satisfies the following conditions: the thickness of the optical compensation film is 40 μm, the thickness of the co-coated region is 62 μm, and the width of the co-coated region is 0.93 cm.

[0089] Comparative Example 2:

[0090] In this comparative example, an optical compensation film resin coating liquid was directly coated onto a PET film using a slot coating method, and then heated to obtain a dry film. After peeling off the support 1, an optical film was obtained.

[0091] The coating process in this comparative example involves the same PET film conveying speed, slit coating die 2, control parameters of slit coating die 2, pre-drying and calcination conditions as in Example 2.

[0092] The resulting film satisfies the following condition: the thickness of the optical compensation film is 40 μm.

[0093] The optical films of Examples 2 to 6, Comparative Examples 1 and 2 are trimmed (i.e., the edges of the films are trimmed using a cutter during the peeling of the support 1), and generally 2 cm of the edge needs to be removed.

[0094] The cut edges of the optical thin films after edge trimming were observed. Visual inspection revealed that the cut edges of the films in Examples 2 to 6 were smooth and neat, while the cut edges of the films in Comparative Examples 1 and 2 had numerous small notches. (See details below.) Figure 4 As shown.

[0095] The trimmed films (Examples 2 and 6, Comparative Examples 1 and 2) were then fed into a stretching process using the same stretching control technology (e.g., stretching temperature of 110–140°C, stretching ratio of 1.5*1.8TD*MD) to prepare optical compensation films. The films of Comparative Examples 1 and 2 experienced film breakage during the stretching process, failing to form an effective film. The optical performance of the optical compensation films prepared in Examples 2 to 6 was tested, and the results are shown in Table 1 below.

[0096] Table 1 Optical Performance Test Data

[0097] Example 2 Example 3 Example 4 Example 5 Example 6 Detection methods Solvent residue 3.55% 2.48% 3.89% 3.52% 3.37% GB 5009.262-2016 Transmission rate 92.56% 93.04% 92.12% 92.44% 92.02% JIS K7361 Haze 0.89% 0.85% 0.97% 0.86% 0.90% JIS K7361

[0098] Optical compensation films were produced using the method described in Example 2. Ten batches of optical compensation films (each batch yielding 1500 square meters) were sampled and tested, as shown in Table 2 below. The product performance was determined to meet the following requirements: solvent residue ≤4%, transmittance >92%, and haze <1%.

[0099] Table 2 Optical performance test data for each batch of optical films

[0100]

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A co-coating process for edge preparation to suppress edge notches and stretching film breakage, characterized in that: Includes the following steps: (1) Apply an optical functional coating liquid to the support (1). The optical functional coating liquid includes an optical compensation film resin coating liquid; (2) Apply an elastic resin coating to the edge of the support (1) in the transport direction, such that the width of the co-coated area of ​​the elastic resin coating and the optical functional coating is set to 0.9-1.1 cm, and the film thickness of the co-coated area is set to 20-50 μm. The elastic resin coating liquid has a solid content of 10-20%, comprising an optical compensation film resin coating liquid and organic elastic particles, wherein the organic elastic particles account for 1-5 w / w% of the elastic resin coating liquid. The organic elastic particles include one or more of the following: ultra-high molecular weight polyethylene particles, polypropylene particles, polyimide resin particles, acrylonitrile-butadiene-styrene copolymer resin particles, and polyester resin particles with 8 or more carbon atoms. (4) Heat to obtain a dry film; (5) After removing the support (1), a co-coated film is obtained at the edges. In steps (1) and (2), the optical compensation film resin coating liquid includes one or more of the following: methacrylic resin, polycarbonate resin, cellulose resin, polyester resin, polyester carbonate resin, polyvinyl alcohol acetal resin, olefin resin, and polyurethane resin.

2. The edge co-coating preparation process according to claim 1, characterized in that: The optical compensation film resin coating liquid contains at least a compensation film resin, a leveling agent, and an organic solvent.

3. The edge co-coating preparation process according to claim 1, characterized in that: The coating methods for the optical functional coating liquid or elastic resin coating liquid include slot coating, roller coating, doctor blade coating, reverse coating, gravure coating, spray coating, air knife coating, or wire bar coating.

4. The edge co-coating preparation process according to claim 1, characterized in that: The heating includes pre-baking and calcination after pre-baking. The pre-baking temperature is set to 50-100℃ and the time is set to 15s-10min. The calcination temperature is set to 100-200℃ and the time is set to 5-200min.

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