TAC-less ultra-thin polarizing plate preparation method and structure based on water-glue thermal curing

Abstract

The present application relates to the technical field of polarizer preparation, and particularly relates to a TAC Less ultrathin polarizer preparation method and structure based on water glue hot curing, which comprises the following steps: forming a temporary support layer by coating silica on the surface of a PET substrate to form a release coating layer; adding water glue to a glue roller in a preset water glue drop amount to form a first water glue layer; determining a stretching proportion coefficient according to the water glue drop amount and the water content of the measured water glue layer, and stretching a PVA polarizing film to form a polarizing film PVA layer; pre-rolling and bonding the temporary support layer and the polarizing film PVA layer through a pressure roller slit; determining the adjustment of the stretching proportion coefficient according to the water content change value of the water glue layer; and compensating the preset water glue drop amount of the first water glue layer according to the water glue layer shrinkage state of the first water glue layer in the stretching proportion coefficient adjustment process. The present application replaces the traditional UV glue with water glue, and combines parameter collaborative control to simplify the process and reduce the cost. The obtained polarizer has uniform thickness and stable performance.

Description

Technical Field

[0001] This invention relates to the field of polarizer fabrication technology, and in particular to a method and structure for fabricating TAC Less ultrathin polarizers based on water-based thermosetting adhesive. Background Technology

[0002] The current mainstream TAC-less ultrathin polarizer fabrication technology uses cellulose triacetate (TAC) film as a temporary support substrate and utilizes UV-cured adhesive layers to bond the polarizer PVA layer to the temporary support layer. Specifically, the adhesive layer undergoes gradient curing control through UV irradiation time and intensity, keeping the adhesive layer at the TAC temporary support layer interface in a weakly cured state while the normal TAC functional layer side is fully cured. Finally, the TAC temporary support layer is peeled off to form a single-sided unsupported ultrathin structure.

[0003] Chinese utility model patent CN202122444737.0 discloses a light-blocking polarized ultra-thin lens. The substrate consists of an outer PA layer and an inner PC layer, bonded together with UV adhesive. The outer side of the PA layer is sequentially provided with a first polarizing film, a first PVA film, a hardening film, a first waterproof layer, and a first oil-resistant layer. The inner side of the PC layer is sequentially provided with a second polarizing film, a second PVA film, a second waterproof layer, and a second oil-resistant layer. This utility model integrates the functions of PA and PC materials, resulting in a thinner, lighter, and more impact-resistant lens with improved light-blocking and polarizing effects. It effectively removes harmful ultraviolet and blue light below 580nm, while increasing the transmittance of other visible light, making objects appear brighter, clearer, and more natural. It significantly reduces glare and better protects the retina and eyes. Testing shows that the product effectively blocks 99% of ultraviolet and blue light, is 60% lighter than ordinary lenses, and is suitable for manufacturing high-end sunglasses lenses.

[0004] However, the following technical defects still exist:

[0005] Firstly, the heavy reliance on imported UV adhesives and high-precision photocuring equipment results in persistently high production costs.

[0006] Secondly, the UV curing process is sensitive to the uniformity of light exposure and the temperature and humidity of the environment, which can easily cause fluctuations in the peel strength of the adhesive layer and restrict the stability of mass production.

[0007] Third, TAC film and UV adhesive materials are difficult to be compatible with domestic alternatives, and there are potential risks to environmental compliance;

[0008] Fourth, there are certain patent restrictions on the formulation and curing process of domestic UV-curable adhesives, which poses a risk to the competitiveness of the products. Summary of the Invention

[0009] To address this issue, the present invention provides a method and structure for preparing TAC Less ultrathin polarizers based on water-based thermosetting adhesives, thereby overcoming the problem of high production costs caused by the heavy reliance on imported UV adhesives and high-precision photocuring equipment in the prior art.

[0010] To achieve the above objectives, on the one hand, the present invention provides a method for preparing a TAC Less ultrathin polarizer based on water-based thermosetting adhesive, comprising the following steps:

[0011] Silica is coated with preset coating process parameters to form a release coating on the surface of a PET substrate to construct a temporary support layer;

[0012] Water-based adhesive is dripped onto the adhesive roller at a preset amount to form the first water-based adhesive layer;

[0013] The stretching ratio coefficient of the PVA polarizing film is determined based on the preset amount of water-based adhesive added and the measured water-based adhesive moisture content of the first water-based adhesive layer, so as to stretch the PVA polarizing film to form a polarizing PVA layer.

[0014] The temporary support layer and the polarizing PVA layer are pre-rolled and bonded together by a pressure roller slit;

[0015] The stretching ratio coefficient is adjusted based on the change in moisture content of the water-based adhesive layer over several time intervals.

[0016] Based on the shrinkage state of the first water-based adhesive layer during the stretching ratio adjustment process, the preset water-based adhesive droplet addition amount of the first water-based adhesive layer is determined to compensate for the first water-based adhesive layer.

[0017] A second water-based adhesive layer is formed by dripping water-based adhesive between the polarizing PVA layer and the TAC film, and the temporary support layer, the polarizing PVA layer and the TAC film are then positively pressed together through a pressure roller slit to obtain the first polarizing film.

[0018] The first polarizer is subjected to a staged heating and curing process to obtain the second polarizer;

[0019] The temporary support layer of the second polarizer is mechanically peeled off to complete the fabrication of the polarizer.

[0020] Furthermore, the process of determining the preset coating process parameters includes:

[0021] Obtain the first surface roughness of the PET substrate and compare the first surface roughness with a preset roughness;

[0022] The coating process parameters are determined as the first coating process parameters based on the comparison result that the first surface roughness is less than or equal to the preset roughness;

[0023] Alternatively, the coating process parameters can be determined as the second coating process parameters based on the comparison result that the first surface roughness is greater than the preset roughness;

[0024] The first coating process parameters include setting the coating speed to 8-10 m / min, the coating thickness to 1.0-1.5 μm, and the drying temperature to 100-120℃.

[0025] The second coating process parameters include setting the coating speed to 5-7 m / min, the coating thickness to 1.5-2.0 μm, and the drying temperature to 80-100℃.

[0026] Furthermore, the process of forming a release coating on the surface of the PET substrate includes:

[0027] The roughness of the release coating during the coating process is acquired in real time.

[0028] The second surface roughness and the second roughness dispersion coefficient are determined based on the acquired roughness.

[0029] Based on the comparison between the second roughness dispersion coefficient and the standard roughness dispersion coefficient, the coating speed is re-determined.

[0030] Furthermore, the process of determining the second surface roughness and the second roughness discrete coefficient based on the acquired roughnesses includes:

[0031] Several roughness values ​​of the release coating are obtained, and the average value of the several roughness values ​​is determined as the second surface roughness;

[0032] The standard deviation of the second surface roughness is determined based on the second surface roughness and the plurality of roughnesses;

[0033] The percentage result of the square root of the ratio of the standard deviation to the second surface roughness is determined as the second roughness dispersion coefficient.

[0034] Furthermore, the process of determining the preset amount of water-based adhesive added includes:

[0035] Obtain the third surface roughness of the release coating, and determine the coating area coverage based on the third surface roughness and the first surface roughness;

[0036] Based on the comparison between the coating area coverage and the standard coating area coverage, the preset amount of water-based adhesive is determined.

[0037] Furthermore, the process of determining the stretching ratio of the PVA polarizing film includes:

[0038] The first ratio is calculated as the ratio of the preset water-based adhesive addition amount to the standard preset water-based adhesive addition amount.

[0039] The ratio of the water-based adhesive's moisture content to the standard water-based adhesive's moisture content is calculated as the second ratio.

[0040] The weighted sum of the first ratio and the second ratio is determined as the stretching ratio parameter.

[0041] The stretching ratio parameter is determined based on the comparison between the stretching ratio parameter and the standard stretching ratio parameter.

[0042] Furthermore, the process of determining the adjustment of the stretching ratio coefficient includes:

[0043] The moisture content of the first water-based adhesive layer before pre-roll pressing and bonding in the pressure roller slit and the moisture content of the second water-based adhesive layer after pre-roll pressing and bonding in the pressure roller slit are obtained.

[0044] The moisture content deviation of the water-adhesive layer is determined based on the moisture content of the first water-adhesive layer and the moisture content of the second water-adhesive layer.

[0045] Based on the comparison between the moisture content deviation and the standard deviation of the water-based adhesive layer, it is determined that the stretching ratio coefficient should be adjusted.

[0046] Furthermore, the process of determining the preset amount of water-based adhesive added to the first water-based adhesive layer for compensation includes:

[0047] Real-time acquisition of microscopic images of the side of the first hydrogel layer;

[0048] Based on the microscopic image, a gap dataset is generated by obtaining several interval gaps in the first hydrogel layer to determine the shrinkage state parameters of the hydrogel layer.

[0049] Based on the comparison between the shrinkage state parameter of the water-based adhesive layer and the shrinkage state parameter of the standard water-based adhesive, the preset amount of water-based adhesive added to the first water-based adhesive layer is determined to be compensated.

[0050] Furthermore, the process of performing a staged temperature-curing treatment on the first polarizer includes:

[0051] The first step of heating is at 50℃ and lasts for 2 minutes;

[0052] The second stage of heating is at 60℃ and lasts for 4 minutes;

[0053] The third stage of heating is at 70℃ and lasts for 4 minutes;

[0054] The fourth stage of heating is at 60℃ and lasts for 2 minutes.

[0055] On the other hand, the present invention provides a TAC Less ultrathin polarizer structure, comprising:

[0056] The temporary support layer is formed by coating the surface of a PET substrate with silica to form a release coating, followed by drying.

[0057] The first water-based adhesive layer is formed by applying water-based adhesive to the release coating;

[0058] The polarizing film PVA layer is formed by stretching a PVA polarizing film through a wet stretching process.

[0059] The second water-based adhesive layer is formed by applying adhesive to the polarizing film PVA layer.

[0060] The functional layer is a TAC membrane;

[0061] The first polarizer is formed by pressing the temporary support layer, the first water-based adhesive layer, the polarizing film PVA layer, the second water-based adhesive layer, and the functional layer together by a pressure roller slit.

[0062] The second polarizer is formed by peeling the temporary support layer from the first water-based adhesive layer after the first polarizer has been cured by step heating.

[0063] This invention focuses on the polarizer manufacturing process. By precisely controlling and synergistically optimizing the parameters of each production stage, it successfully breaks through the dependence on imported UV adhesives and high-precision photocuring equipment, significantly reducing production costs. The specific optimization measures and results are as follows:

[0064] By replacing the traditional UV adhesive system with a water-based thermosetting process, the reliance on imported high-precision photocuring equipment is eliminated, reducing equipment investment costs by more than 40%. At the same time, the use of domestically produced water-soluble polyvinyl alcohol adhesive (solid content 5% to 10%, viscosity 15 to 30 cps) reduces material costs by 30% to 50% compared to imported UV adhesives, enabling low-cost domestic mass production of TAC Less ultrathin polarizers.

[0065] Furthermore, the coating speed, thickness, and drying temperature are dynamically adjusted according to the surface roughness of the PET substrate (controlled between 0.5 and 1.0 μm) to ensure that the release coating does not completely cover the substrate roughness, balance the adhesion between the coating and the water-based adhesive layer, and simultaneously remove the water-based adhesive layer during peeling to ensure the cleanliness of the PVA polarizing film surface.

[0066] Furthermore, the coating speed is controlled in real time based on the second roughness dispersion coefficient. By detecting the second roughness dispersion coefficient of the release coating online, the wetting time of silica on the rough surface is extended, and the contact area between the release coating and the PET substrate is precisely controlled, thereby increasing the adhesion of the release coating on the PET substrate and ensuring the peeling effect of the temporary support layer.

[0067] Furthermore, based on the precise control of the amount of water-based adhesive for roughness coverage, the amount of water-based adhesive added is adjusted inversely by calculating the ratio of the difference between the surface roughness and the measured roughness (i.e., the coating area coverage), thereby reducing shrinkage caused by excessive moisture content and ensuring the bonding effect between the PVA polarizing film and the first water-based adhesive layer.

[0068] Furthermore, by analyzing the side gaps of the first hydrogel layer through microscopic imaging, when the shrinkage parameter is greater than the standard value, the preset amount of hydrogel added to the first hydrogel layer is increased proportionally to compensate for the edge defects caused by shrinkage. This systematically solves the problem of dependence on imported materials and equipment in existing technologies, reduces production costs while improving product yield and process stability, and provides a low-cost and high-efficiency technical path for the domestic mass production of TAC Less ultrathin polarizers. Attached Figure Description

[0069] Figure 1 This is a flowchart illustrating the steps of the method for preparing TAC Less ultrathin polarizer based on water-based thermosetting in an embodiment of the present invention.

[0070] Figure 2 This is a flowchart illustrating the steps of determining the second surface roughness and the second roughness dispersion coefficient based on several obtained roughnesses in an embodiment of the present invention.

[0071] Figure 3 A flowchart illustrating the steps for determining the stretching ratio of a PVA polarizing film in an embodiment of the present invention;

[0072] Figure 4 This is a schematic diagram of the structure of the TAC Less ultrathin polarizer based on water-based thermosetting according to an embodiment of the present invention;

[0073] Figure 5 This is a schematic diagram of the process flow for the preparation method of TAC Less ultrathin polarizer based on water-based thermosetting adhesive according to the present invention.

[0074] Figure 6 This is a three-dimensional structural diagram of the pre-rolling device according to an embodiment of the present invention;

[0075] In the diagram: 1-PET substrate layer, 2-release coating, 3-first water-based adhesive layer, 4-polarizing PVA layer, 5-second water-based adhesive layer; 6-functional layer, 7-water tank, 8-first stretching roller, 9-second stretching roller, 10-PVA polarizing film roll; 11-first temporary support layer water-based adhesive dispensing roller; 12-second temporary support layer water-based adhesive dispensing roller, 13-first water-based adhesive dispensing device, 14-temporary support layer roll, 15-temporary support layer, 16-first feeding roller, 17- 18-Second feeding roller, 19-First pre-roll pressing roller, 20-Water-replenishing glue needle, 20-1-Water-replenishing glue storage box, 21-TAC film roll, 22-First TAC film water-replenishing glue dripping roller, 23-Second TAC film water-replenishing glue dripping roller, 24-Second water-replenishing glue dripping device, 25-First positive roller pressing roller, 26-Second positive roller pressing roller, 27-TAC film, 28-PVA polarizing film, 29-Adsorption roller, 29-1-Suction hole, 30-Microscopic imaging device. Detailed Implementation

[0076] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0077] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0078] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0079] Please see Figure 1 As shown, Figure 1 This is a flowchart illustrating the steps of a method for preparing a TAC Less ultrathin polarizer based on water-based thermosetting adhesive, according to an embodiment of the present invention.

[0080] This invention relates to a method for preparing TAC Less ultrathin polarizing films based on water-based thermosetting adhesive, comprising the following steps:

[0081] Silica is coated with preset coating process parameters to form a release coating on the surface of a PET substrate to construct a temporary support layer;

[0082] Water-based adhesive is dripped onto the adhesive roller at a preset amount to form the first water-based adhesive layer;

[0083] The stretching ratio coefficient of the PVA polarizing film is determined based on the preset amount of water-based adhesive added and the measured water content of the first water-based adhesive layer, so as to stretch the PVA polarizing film to form a polarizing PVA layer.

[0084] The temporary support layer and the polarizing PVA layer are pre-rolled and bonded together using a pressure roller slit;

[0085] The stretching ratio coefficient is adjusted based on the change in moisture content of the adhesive layer over several time intervals.

[0086] The preset amount of water-based adhesive added to the first water-based adhesive layer is determined to compensate for the shrinkage state of the first water-based adhesive layer during the adjustment of the stretching ratio coefficient.

[0087] A second water-based adhesive layer is formed by dripping water-based adhesive between the polarizing PVA layer and the TAC film. The temporary support layer, the polarizing PVA layer and the TAC film are then positively pressed together through the slit of the pressure roller to obtain the first polarizing film.

[0088] The first polarizer is subjected to a staged heating and curing process to obtain the second polarizer;

[0089] The temporary support layer of the second polarizer is mechanically peeled off to complete the fabrication of the polarizer.

[0090] Specifically, the thickness of the TAC film in this embodiment of the invention is 20–40 μm.

[0091] Specifically, the process of determining the preset coating process parameters includes:

[0092] Obtain the first surface roughness of the PET substrate and compare it with a preset roughness;

[0093] The coating process parameters are determined as the first coating process parameters based on the comparison results where the first surface roughness is less than or equal to the preset roughness.

[0094] Alternatively, the coating process parameters can be determined as the second coating process parameters based on the comparison results of the first surface roughness being greater than the preset roughness;

[0095] The first coating process parameters include setting the coating speed to 8-10 m / min, the coating thickness to 1.0-1.5 μm, and the drying temperature to 100-120℃.

[0096] The second coating process parameters include setting the coating speed to 5-7 m / min, the coating thickness to 1.5-2.0 μm, and the drying temperature to 80-100℃.

[0097] It is understandable that roughness is the arithmetic mean of the planar profile offset. The smaller the value, the smoother the surface and the weaker the surface adhesion. Conversely, the larger the value, the rougher the surface and the stronger the surface adhesion. In order to balance the adhesion between the release coating and the first water-based adhesive layer, the thickness of the release coating should be controlled to be insufficient to completely cover the surface roughness when applying the release coating. Even if a part of the surface roughness is retained in the release coating, it is necessary to balance the adhesion between the release coating and the first water-based adhesive layer and ensure that the first water-based adhesive layer is peeled off at the same time during the peeling process of the temporary support layer, so as to ensure the surface cleanliness of the complete polarizer PVA layer.

[0098] Specifically, in this embodiment of the invention, the roughness of the first surface is controlled between 0.5 and 1.0 μm, and the preset roughness is set to 0.6 times the roughness to ensure the adhesion between the release coating surface and the first water-based adhesive layer.

[0099] Specifically, the process of forming a release coating on the surface of a PET substrate includes:

[0100] Real-time acquisition of several roughness parameters of the release coating during the coating process;

[0101] The second surface roughness and the second roughness dispersion coefficient are determined based on the obtained roughness values;

[0102] Based on the comparison between the second roughness dispersion coefficient and the standard roughness dispersion coefficient, the coating speed is re-determined. The second roughness dispersion coefficient is inversely proportional to the coating speed.

[0103] Specifically, in this embodiment of the invention, the standard roughness dispersion coefficient is set to 5% to 10%.

[0104] If the second roughness dispersion coefficient is less than or equal to 5%, then adjust and increase the coating speed to 8-10 m / min;

[0105] If the second roughness dispersion coefficient is greater than 5% and less than 10%, then the coating speed should be adjusted to 5-7 m / min.

[0106] Otherwise, trigger a control accuracy warning for the coating machine.

[0107] Understandably, the second surface roughness is the average of several roughness values ​​collected on the release coating surface. The second roughness indicates the change in roughness height of the release coating during the coating process, and the second roughness dispersion coefficient indicates the change in the degree of undulation of the rough points of the release coating during the coating process. Therefore, the larger the second roughness dispersion coefficient, the slower the coating speed, so as to increase the residence time of the silica used for coating on the rough surface, so that the silica can better impregnate and precipitate on the PET substrate surface, ensuring the contact area between silica and the rough surface of the PET substrate, thereby increasing the adhesion of the release coating on the PET substrate surface.

[0108] Please see Figure 2 , Figure 2 This is a flowchart illustrating the steps of determining the second surface roughness and the second roughness dispersion coefficient based on several obtained roughnesses in an embodiment of the present invention.

[0109] Specifically, the process of determining the second surface roughness and the second roughness discrepancy coefficient based on the acquired roughnesses includes:

[0110] Several roughness values ​​of the release coating are obtained, and the average value of the several roughness values ​​is determined as the second surface roughness.

[0111] The standard deviation of the second surface roughness is determined based on the second surface roughness and several roughnesses;

[0112] The percentage result of the square root of the ratio of the standard deviation to the second surface roughness is determined as the second roughness dispersion coefficient.

[0113] Specifically, in this embodiment of the invention, the roughness value of the release coating is detected to be Ra1 to Ra5, and the second surface roughness is calculated according to the following formula:

[0114]

[0115] The standard deviation of the second surface roughness is calculated using the following formula:

[0116]

[0117] The second roughness dispersion coefficient is calculated using the following formula:

[0118]

[0119] Specifically, the process of determining the preset amount of water-based adhesive to be added includes:

[0120] Obtain the third surface roughness of the release coating, and determine the coating area coverage based on the third surface roughness and the first surface roughness;

[0121] Based on the comparison between the coating area coverage and the standard coating area coverage, the preset water-based adhesive addition amount is determined. The coating area coverage and the preset water-based adhesive addition amount are inversely proportional.

[0122] Specifically, the roughness difference between the first surface roughness and the third surface roughness is calculated, and the ratio of the roughness difference to the first surface roughness is determined as the coating area coverage. For example, if the first surface roughness is 8% and the third surface roughness is 5%, then the calculated coating area coverage is:

[0123]

[0124] In this embodiment of the invention, the water-based adhesive layer is a water-soluble polyvinyl alcohol adhesive with a solid content of 5% to 10% and a viscosity of 15 to 30 cps, and the standard coating area coverage is 60% to 75%.

[0125] If the coating area coverage is less than 60%, then the preset water-based adhesive droplet addition amount is determined to be 40 g / m². 2 ;

[0126] If the coating area coverage is greater than 60% and less than or equal to 75%, then the preset water-based adhesive droplet addition amount is determined to be 35 g / m². 2 ;

[0127] Otherwise, set the preset water-based adhesive addition amount to 30g / m. 2 .

[0128] Please see Figure 3 , Figure 3 A flowchart illustrating the steps for determining the stretching ratio of the PVA polarizing film in an embodiment of the present invention.

[0129] Specifically, the process of determining the stretching ratio coefficient of PVA polarizing film includes:

[0130] The first ratio is calculated as the ratio of the preset water-based adhesive addition amount to the standard preset water-based adhesive addition amount.

[0131] The ratio of the water-based adhesive's moisture content to the standard water-based adhesive's moisture content is calculated as the second ratio.

[0132] The weighted sum of the first ratio and the second ratio is determined as the stretching ratio parameter.

[0133] Based on the comparison between the tensile proportionality coefficient parameter and the standard tensile proportionality coefficient parameter, the tensile proportionality coefficient is determined, and the tensile proportionality coefficient is inversely proportional to the tensile proportionality coefficient parameter.

[0134] In this embodiment of the invention, the weighting coefficient of the first ratio is set to 0.4, the weighting coefficient of the second ratio is set to 0.6, the stretched thickness of the PVA polarizing film is 7-17 μm, the initial thickness is 50 μm, and the standard preset water-based adhesive droplet addition is set to 40 g / m. 2 The standard water-based adhesive has a moisture content of 95% and a standard tensile ratio parameter of 0.8.

[0135] If the stretching ratio parameter is less than or equal to 0.8, then the stretching ratio is determined to be 150%.

[0136] Otherwise, set the stretching ratio factor to 100%.

[0137] In one embodiment of the present invention, the preset water-based adhesive dripping amount is 30 / m. 2If the water content of the adhesive is 90%, then the first ratio is approximately 0.75, the second ratio is 0.95, and the stretching ratio parameter is 0.87. Therefore, the stretching ratio parameter can be determined to be 150%.

[0138] By measuring the thickness of the stretched PVA polarizing film, the gauge length before and after stretching can be obtained. The stretching ratio coefficient can be determined by the gauge length before and after stretching. The moisture content of the PVA polarizing film should be maintained at 10% to 30% before stretching and reduced to 5% to 10% after stretching. If the moisture content is too high after stretching, the PVA polarizing film will shrink. Determining the stretching ratio coefficient based on the moisture content of the adhesive is to reduce the shrinkage rate of the PVA polarizing film during the lamination process.

[0139] Specifically, the process of determining the adjustment of the stretching ratio factor includes:

[0140] The moisture content of the first water-based adhesive layer before pre-roll pressing and bonding in the pressure roller slit and the moisture content of the second water-based adhesive layer after pre-roll pressing and bonding in the pressure roller slit are obtained.

[0141] The moisture content deviation of the water-based adhesive layer is determined based on the moisture content of the first water-based adhesive layer and the moisture content of the second water-based adhesive layer.

[0142] Based on the comparison between the moisture content deviation and the standard deviation of the adhesive layer, it was determined that the stretching ratio coefficient should be adjusted, as the moisture content deviation of the adhesive layer is directly proportional to the stretching ratio coefficient.

[0143] In this embodiment of the invention, the moisture content deviation of the water-based adhesive layer is the difference between the moisture content of the first water-based adhesive and the moisture content of the second water-based adhesive, representing the change in the moisture content of the water-based adhesive before and after the pressure roller slit pre-pressing and bonding.

[0144] Specifically, in this embodiment of the invention, the standard deviation is set to 5%;

[0145] If the moisture content deviation of the water-based adhesive layer is greater than or equal to 5%, then the adjustment range for increasing the stretching ratio coefficient should be 5% to 10%.

[0146] Otherwise, determine that the stretching ratio factor should not be adjusted.

[0147] Please see Figure 5 , Figure 5 This is a schematic diagram of the process flow for the preparation method of TAC Less ultrathin polarizer based on water-based thermosetting adhesive according to the present invention.

[0148] Specifically, the PVA polarizing film 28 is stretched by the first stretching roller 8 and the second stretching roller 9 in the water tank 7. During the stretching process, the stretching ratio coefficient of the PVA polarizing film 28 is controlled by the speed difference between the PVA polarizing film roll 10 and the second stretching roller 9. The faster the speed of the second stretching roller 9, the larger the stretching ratio coefficient. In this embodiment of the invention, adjusting the stretching ratio coefficient is essentially adjusting the speed of the second stretching roller 9. To ensure synchronization of the rolling process, the speed of each feeding roller and the rolling roller is kept consistent with the speed of the second stretching roller 9.

[0149] Specifically, the process of compensating for the preset amount of water-based adhesive added to the first water-based adhesive layer includes:

[0150] Real-time acquisition of microscopic images of the side of the first hydrogel layer;

[0151] Based on the microscopic images, several interval gaps in the first hydrogel layer are obtained to generate a gap dataset in order to determine the parameters of the hydrogel layer shrinkage state.

[0152] Based on the comparison between the shrinkage state parameter of the water-based adhesive layer and the shrinkage state parameter of the standard water-based adhesive, the preset water-based adhesive drop addition amount of the first water-based adhesive layer is determined to be compensated. The shrinkage state parameter of the water-based adhesive layer is directly proportional to the preset water-based adhesive drop addition amount.

[0153] Specifically, a gap dataset is generated by acquiring several interval gaps in the first hydrogel layer using the microscopic imaging device 30, and the average gap width, gap density, and maximum gap length are obtained based on the interval gap dataset.

[0154] The shrinkage parameters of the hydrogel layer are determined by a weighted sum of the mean gap width, gap density, and maximum gap length.

[0155] The influence weight of the average gap width is set to 0.5, the influence weight of the gap density is set to 0.3, and the maximum gap length is set to 0.2.

[0156] Specifically, in this embodiment of the invention, the microscopic imaging module uses an Olympus BX53M, equipped with a 50-100x objective lens, and is paired with a high-speed camera of model Baslerac A2040-90um, with a resolution of not less than 2048×2048 pixels.

[0157] The light source uses a coaxial LED ring light with a wavelength of 525nm (green light) to enhance the contrast between the water-based adhesive layer and the substrate.

[0158] Understandably, the following problems may arise in practical applications:

[0159] High-speed movement of the rubber roller (7-9 m / min) may cause image motion blur. To solve this problem, a strobe light source (pulse width ≤ 10 μs) and a global shutter camera can be used to freeze the moving image. At the same time, the position of the rubber roller can be obtained in real time through an encoder to trigger dynamic ROI tracking and reduce invalid data processing.

[0160] The surface roughness (0.5–1.0 μm) of the release coating may form false defect signals. To solve this problem, a background database can be established, and the texture features of the standard release coating can be extracted by principal component analysis (PCA). The difference method can be used to remove background noise. For example, an image of the empty substrate can be acquired before inspection, and the difference operation can be performed with the real-time image to highlight the gap defect.

[0161] The parameters such as the amount of water-based adhesive added, moisture content, and stretching ratio are interrelated. Adjusting a single parameter may trigger a chain reaction. To solve this problem, a multivariate model can be established using response surface methodology (RSM), and the parameter combination can be optimized through design of experiments (DOE). For example, when compensating for the amount of water-based adhesive added, the stretching ratio can be adjusted simultaneously to ensure that the shrinkage rate of the PVA film is ≤3%.

[0162] In one example of this invention, the standard shrinkage parameter of the water-based adhesive is 0.8. The specific value is determined based on the actual situation.

[0163] If the shrinkage parameter of the adhesive layer is less than 0.8, then no adjustment is required.

[0164] Otherwise, the preset water-based adhesive addition amount for the first water-based adhesive layer is increased by 1 g / m². 2 .

[0165] Specifically, after the temporary support layer 15 and the PVA polarizing film 28 are pre-pressed together by the pressure roller slit, when the preset water-based adhesive droplet addition amount for the first water-based adhesive layer is determined to be increased, the adsorption roller 29 is first kept in an air-suction state. The adsorption roller 29 forms a vacuum negative pressure on the surface of the temporary support layer 15 during rolling through the air suction hole 29-1. At this time, the PVA polarizing film 28 is temporarily separated from the temporary support layer 15, and 1g / m³ of water-based adhesive is obtained through the water-based adhesive storage box 20-1 via the water-based adhesive needles 20 on both sides. 2 The water-based adhesive is dripped onto the temporarily separated area. After compensation is completed, the adsorption roller 29 loses its air-absorbing state, and the PVA polarizing film 28 and the temporary support layer 15 are restored to contact.

[0166] Please see Figure 6 , Figure 6 This is a three-dimensional structural diagram of the pre-rolling device according to an embodiment of the present invention.

[0167] In this embodiment of the invention, the specific process of positive pressure bonding of the temporary support layer 15, the PVA polarizing film 28, and the TAC film 27 through the pressure roller slit is as follows:

[0168] The temporary support layer 15 is rotated by the temporary support layer roll 14 to reach the first water glue dripping roller, which includes the first water glue dripping device 13, the first temporary support layer water glue dripping roller 11 and the second temporary support layer water glue dripping roller 12. After the water glue dripping is completed here and the first water glue layer is formed, it is conveyed to the first pre-roll pressing roller 18 and the second pre-roll pressing roller 19.

[0169] The PVA polarizing film 28 is brought to the water tank 7 by the rotation of the PVA polarizing film roll 10. The PVA polarizing film 28 is stretched by the first stretching roller 8 and the second stretching roller 9 in the water tank 7. After stretching is completed, the PVA polarizing film 28 is conveyed to the first pre-rolling roller 18 and the second pre-rolling roller 19 by the first feeding roller 16 and the second feeding roller 17.

[0170] The temporary support layer 15 and the PVA polarizing film 28 are pre-rolled and bonded together by the first pre-rolling roller 18 and the second pre-rolling roller 19. When it is necessary to compensate for the increase of the preset water adhesive droplet amount of the first water adhesive layer, the suction hole 29-1 on the adsorption roller 29 temporarily separates the PVA polarizing film 28 from the temporary support layer, and water adhesive is dripped onto the temporary separation point through the water adhesive needle 20.

[0171] The TAC membrane 27 is rotated by the TAC membrane roll 21 to reach the second water adhesive dispensing roller, which includes a second water adhesive dispensing device 24, a first TAC membrane water adhesive dispensing roller 22 and a second TAC membrane water adhesive dispensing roller 23. After the adhesive is dispensed here to form a second water adhesive layer, it is conveyed to the first positive roller pressing roller 25 and the second positive roller pressing roller 26. After the water adhesive dispensing amount is compensated, the formal rolling is completed by the first positive roller pressing roller 25 and the second positive roller pressing roller 26.

[0172] In this embodiment of the invention, the process of performing a staged temperature-curing treatment on the first polarizer includes:

[0173] The first step of heating is at 50℃ and lasts for 2 minutes;

[0174] The second stage of heating is at 60℃ and lasts for 4 minutes;

[0175] The third stage of heating is at 70℃ and lasts for 4 minutes;

[0176] The fourth stage of heating is at 60℃ and lasts for 2 minutes.

[0177] In this embodiment of the invention, when the temporary support layer of the second polarizer is mechanically removed, the peeling force is 0.1 to 0.3 N / 25 mm and the linear speed is 7 to 9 m / min.

[0178] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of the TAC Less ultrathin polarizer based on water-based thermosetting according to an embodiment of the present invention.

[0179] An embodiment of the present invention provides a TAC Less ultrathin polarizer structure based on water-based thermosetting adhesive, comprising:

[0180] The temporary support layer is formed by coating the surface of a PET substrate with silica to form a release coating, followed by drying.

[0181] The first water-based adhesive layer is formed by applying water-based adhesive to the release coating.

[0182] The polarizing film PVA layer is formed by stretching a PVA polarizing film through a wet stretching process.

[0183] The second water-based adhesive layer is formed by applying adhesive to the polarizing PVA layer.

[0184] The functional layer is a TAC membrane;

[0185] The first polarizer is formed by pressing a temporary support layer, a first water-based adhesive layer, a polarizing film PVA layer, a second water-based adhesive layer, and a functional layer together by a pressure roller through a slit.

[0186] The second polarizer is formed by peeling the temporary support layer from the first water-based adhesive layer after the first polarizer has been cured by step heating.

[0187] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention; various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting adhesive, characterized in that, include: Silica is coated with preset coating process parameters to form a release coating on the surface of a PET substrate to construct a temporary support layer; Water-based adhesive is dripped onto the adhesive roller at a preset amount to form the first water-based adhesive layer; The stretching ratio coefficient of the PVA polarizing film is determined based on the preset amount of water-based adhesive added and the measured water-based adhesive moisture content of the first water-based adhesive layer, so as to stretch the PVA polarizing film to form a polarizing PVA layer. The temporary support layer and the polarizing PVA layer are pre-rolled and bonded together by a pressure roller slit; The stretching ratio coefficient is adjusted based on the change in moisture content of the water-based adhesive layer over several time intervals. Based on the shrinkage state of the first water-based adhesive layer during the adjustment of the stretching ratio coefficient, the preset amount of water-based adhesive added to the first water-based adhesive layer is determined to compensate for the amount of water-based adhesive added to the first water-based adhesive layer. A second water-based adhesive layer is formed by dripping water-based adhesive between the polarizing PVA layer and the TAC film, and the temporary support layer, the polarizing PVA layer and the TAC film are then positively pressed together through a pressure roller slit to obtain the first polarizing film. The first polarizer is subjected to a staged heating and curing process to obtain the second polarizer; The temporary support layer of the second polarizer is mechanically peeled off to complete the preparation of the polarizer; The process of determining the preset amount of water-based adhesive added to the first water-based adhesive layer for compensation includes: Real-time acquisition of microscopic images of the side of the first hydrogel layer; Based on the microscopic image, a gap dataset is generated by obtaining several interval gaps in the first hydrogel layer to determine the shrinkage state parameters of the hydrogel layer. Based on the comparison between the shrinkage state parameter of the water-based adhesive layer and the shrinkage state parameter of the standard water-based adhesive, the preset amount of water-based adhesive added to the first water-based adhesive layer is determined to be compensated.

2. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 1, characterized in that, The process of determining the preset coating process parameters includes: Obtain the first surface roughness of the PET substrate and compare the first surface roughness with a preset roughness; The coating process parameters are determined as the first coating process parameters based on the comparison result that the first surface roughness is less than or equal to the preset roughness; Alternatively, the coating process parameters can be determined as the second coating process parameters based on the comparison result that the first surface roughness is greater than the preset roughness; The first coating process parameters include setting the coating speed to 8~10m / min, the coating thickness to 1.0~1.5μm, and the drying temperature to 100~120℃. The second coating process parameters include setting the coating speed to 5~7m / min, the coating thickness to 1.5~2.0μm, and the drying temperature to 80~100℃.

3. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 2, characterized in that, The process of forming a release coating on the surface of the PET substrate includes: The roughness of the release coating during the coating process is acquired in real time. The second surface roughness and the second roughness dispersion coefficient are determined based on the acquired roughness. Based on the comparison between the second roughness dispersion coefficient and the standard roughness dispersion coefficient, the coating speed is re-determined.

4. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 3, characterized in that, The process of determining the second surface roughness and the second roughness dispersion coefficient based on the acquired roughness includes: Several roughnesses of the release coating are obtained, and the average value of the several roughnesses is determined as the second surface roughness; The standard deviation of the second surface roughness is determined based on the second surface roughness and the plurality of roughnesses; The percentage of the square root of the ratio of the standard deviation to the second surface roughness is determined as the second roughness dispersion coefficient.

5. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 4, characterized in that, The process of determining the preset amount of water-based adhesive added includes: Obtain the third surface roughness of the release coating, and determine the coating area coverage based on the third surface roughness and the first surface roughness; Based on the comparison between the coating area coverage and the standard coating area coverage, the preset amount of water-based adhesive is determined.

6. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 5, characterized in that, The process of determining the stretching ratio of the PVA polarizing film includes: The first ratio is calculated as the ratio of the preset water-based adhesive addition amount to the standard preset water-based adhesive addition amount. The ratio of the water-based adhesive's moisture content to the standard water-based adhesive's moisture content is calculated as the second ratio. The weighted sum of the first ratio and the second ratio is determined as the stretching ratio parameter. The stretching ratio parameter is determined based on the comparison between the stretching ratio parameter and the standard stretching ratio parameter.

7. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 6, characterized in that, The process of determining the adjustment of the stretching ratio coefficient includes: The moisture content of the first water-based adhesive layer before pre-roll pressing and bonding in the pressure roller slit and the moisture content of the second water-based adhesive layer after pre-roll pressing and bonding in the pressure roller slit are obtained. The moisture content deviation of the water-adhesive layer is determined based on the moisture content of the first water-adhesive layer and the moisture content of the second water-adhesive layer. Based on the comparison between the moisture content deviation and the standard deviation of the water-based adhesive layer, it is determined that the stretching ratio coefficient should be adjusted.

8. The method for preparing TAC Less ultrathin polarizing film based on water-based thermosetting according to claim 7, characterized in that, The process of performing a staged temperature-curing treatment on the first polarizer includes: The first step of heating is at 50℃ and lasts for 2 minutes; The second stage of heating is at 60℃ and lasts for 4 minutes; The third stage of heating is at 70℃ and lasts for 4 minutes; The fourth stage of heating is at 60℃ and lasts for 2 minutes.

9. The TAC Less ultrathin polarizer structure obtained by applying the method for preparing TAC Less ultrathin polarizer based on water-based thermosetting according to any one of claims 1-8, characterized in that, include: The temporary support layer is formed by coating the surface of a PET substrate with silica to form a release coating, followed by drying. The first water-based adhesive layer is formed by applying water-based adhesive to the release coating; The polarizing film PVA layer is formed by stretching a PVA polarizing film through a wet stretching process. The second water-based adhesive layer is formed by applying adhesive to the polarizing film PVA layer. The functional layer is a TAC membrane; The first polarizer is formed by pressing the temporary support layer, the first water-based adhesive layer, the polarizing film PVA layer, the second water-based adhesive layer, and the functional layer together by a pressure roller slit. The second polarizer is formed by peeling the temporary support layer from the first water-based adhesive layer after the first polarizer has been cured by step heating.

Images