TW201109746A - Manufacturing method for polarizing plate and polarizing plate manufactured thereby - Google Patents

Abstract

The present invention provides a manufacturing method for polarizing plates, which comprises the following steps: A polarizing film treated by an iodine dyeing treatment is processed in a film drying under the temperature between 25 to 50 degree C. And after at least one surface of the polarizing film is bound to a protective film by the adhesive, the polarizing film is processed in an adhesive drying under the temperature between 25 to 55 degree C to obtain the polarizing plate of the present invention. The polarizing plate of the present invention comprises a polarizing layer, at least one protective film and at least one adhesive layer, wherein the adhesive layer is disposed between the polarizing plate and the protective film, the absorption coefficient of the polarizing plate at 480 nm wave length is between 3000 cm-1 to 4000 cm-1 and at 600 nm wave length is between 3000 cm-1 to 4000 cm-1.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing a polarizing plate, and more particularly to a method for producing a polarizing plate using a dual-temperature drying process, and a polarizing plate produced by using the method. [Prior Art] The polarizing plate mainly comprises a polarizing film (p〇larizer) and a protective film adhered to at least one side of the polarizing film with an adhesive. In general, the polarizing film is a hydrophilic fluorene molecule of a polyvinyl alkene (pVA) film which is subjected to a wet production technique including dyeing, crosslinking, stretching, and the like, and The final drying procedure is made in which the dyeing procedure is to soak the pVA film in a bath of dichromatic or dyed dyes, while the moth dyeing process generally uses iodine and potassium iodide as the second. In the directional medium, the PVA film is subjected to polarization polarization characteristics during dyeing and stretching. The advantage of the enamel dyeing treatment is that it is easier to obtain a polarization characteristic with high polarization and high transmittance. The moth dyeing treatment mainly involves the equilibrium reaction of polyiodide (p〇iyi〇dides) formed by moth molecules (i〇dine, ι2) and ion-filling ions (iodide, I). The reaction formula is: 12 + I $ 13_

The 3 + V reaction will form LGriiodide and l5-(pentai〇dide), and the I3 and I5 moth ions will combine with the helical structure of PVA and form the 201109746 I3 -PVA and I5 -PVA Compounds, while I3-PVA and h-PVA produce characteristic absorption near the wavelengths of 480 nm and 600 nm, respectively. The cross-linking sequence after the iodine dyeing treatment is cross-linking with the PVA via a cross-linking agent to form a structural three-dimensional bridge, and also the adhesion of dyeing factors such as ruthenium and osmium to the PVA film. more stable. At present, most of the polarizers required by the industry are expected to have high polarization, contrast and light transmittance. Therefore, the materials used for the polarizing film and the protective film, the composition of the adhesive, the stretching method and equipment, and the iodine concentration in the dye bath. And temperature and so on are continuously developed and improved to obtain polarizers with better optical properties. Among them, in order to control the hue of the dyed polarizing film and to seek a neutral color polarizing plate so that the polarizing plate can be absorbed uniformly in the entire visible light region, and the polyiodide ions form an orderly alignment, it must be controlled. I: The balance between I3 and 15. TW 1269079 discloses a method for producing a polarizing film by sequentially stretching, swelling, iodine dyeing, cross-linking and washing with a PVA film, and drying at 5 ° C for 4 minutes to obtain an iodine type polarizing film, and then a pvA substrate. The adhesive is applied to the two surfaces of the polarizing film to adhere to a protective film of triacetyl cellulose (TAC), and then dried under 5 〇 γ for 5 minutes to obtain a single transmittance of 43.9% (5). And a contrasting polarizing plate of 2〇74, and the manufacturing method of the polarizing plate disclosed by TW584763 is also a pvA film which is sequentially stretched in an iodine/potassium iodide bath and stretched in a boric acid/potassium iodide bath to 50 〇. Drying of the dryer of C' followed by adhesion of a TAc film and a pvA-based adhesive to produce a polarizing plate having a transmittance/polarization system, 43; in addition, in the case of the published TW2(10)638()73__ 201109746 Through the improvement of the acid-cutting process to reduce the shade of the hue, and to obtain a polarizing film with a thick film thickness, wherein, in the content two: the P VA film washed after dyeing is transmitted in Zhao: Falling, dangerous, Λ 浔犋Furnace at a temperature of from about 40~1〇〇〇c row administered approximately 60~_ seconds (i.e., wo minutes), followed by adhesive bonding a. The bonding drying temperature after the protective film is usually from 3 〇 to 85. Preferably, it is a temperature range of about 40 to (d), and in the embodiment of the present invention, the drying temperature of the film and the bonding drying temperature of (4) are exemplified. Thus, in

The improvement in the traditional process is mostly focused on the control and adjustment of the iodine dyeing bath temperature, the cross-linking solution temperature and the subsequent washing temperature, but for the dyeing treatment and the drying temperature conditions after the protective film is adhered, % is regarded as more general. Operating procedures without a more in-depth discussion or a more systematic operational orientation. From the above, it is known that the method for producing a polarizing film and a polarizing plate is still in need of further investigation and development to enhance the optical characteristics of the polarizing plate, and contribute to the improvement of the process of the polarizing plate and the development of the industry. SUMMARY OF THE INVENTION In the research of the process improvement of a polarizing plate, the inventors of the present invention found that, in fact, the film of the broken polarizing film (such as pVA film) after being washed by water is dried, even after the protective film is attached. Drying, both have a great influence on the balance of ΙΓ and 1 in the pVA wrong compound, the absorption coefficient (X) of the polarizing plate at a specific wavelength, such as the absorption coefficient at a wavelength of 480 nm (such as And the absorption coefficient («6〇〇) at a wavelength of 6〇〇nm is changed, and the absorption coefficient is known by the eter law (7) eer_ Lambert law). The absorbance at a specific wavelength of the polarizing plate (absorbance, A) also Change. 201109746

Beer_Lambert law : A=〇.〇434ocL /, medium A shows no absorbance, α means absorption coefficient, ^^), L means film thickness ο From the above, the effect of film drying and lamination drying is not limited to the general removal of water and The solvent in the adhesive, the inventors of the present invention have found that the selection and control of the drying temperature can significantly affect the optical properties of the polarizing film and the polarizing plate produced. An object of the present invention is to provide a method for producing a polarizing plate comprising: treating a polarizing film by iodine dyeing at a temperature of 25 to 50. (: performing a film drying between; and bonding at least one side of the film-dried polarizing film to a protective film with an adhesive at a temperature of 25 to 55. To obtain a polarizing plate comprising a polarizing layer, at least one protective layer and at least one adhesive layer disposed between the polarizing layer and the protective layer, and the wrong compound of the plant-PVA and ir-PVA and the attached thereto The polyiodide ion exists in an equilibrium state. The inventors of the present invention thought that the temperature of the film drying and the bonding drying should affect the equilibrium constant value of the reaction, so after continuous research and testing, the use temperature is between 25 and 50. °C film drying conditions and a low temperature drying process with a temperature of 25 to 55 ° C in parallel drying conditions to effectively regulate the balance of polyiodide ions and their corresponding absorption coefficients at specific wavelengths, and then regulate The hue of the polarizing plate also reduces the influence of the moist heat deterioration which may occur upon heating on the degree of crosslinking of the pVA compound compound 201109746 structure or the PVA film. Another object of the present invention is to provide A polarizing plate produced by the method comprises a polarizing layer, at least one protective layer and at least one adhesive layer, wherein the adhesive layer is disposed between the polarizing layer and the protective layer, and the polarizing plate is The absorption coefficient at a wavelength of 48 〇 nm is between 3 〇〇〇 and 4 〇〇〇 cmi, and the absorption coefficient at a wavelength of 60 〇 nm is between 3 〇〇〇 and side (10). The method of the invention and the effect of the polarizing plate are: the method of the invention firstly adjusts the temperature of the moth dyeing factor in the polarizing film by double-regulating the temperature in the two drying process, and obviously absorbs the absorption coefficient of the specific wavelength of the dyeing, The hue of the polarizing plate can be effectively adjusted, and the effect of improving the degree of polarization and contrast can be achieved. [Embodiment] The foregoing and other technical contents, features and effects of the present invention will be further hereinafter described in the embodiments and the like. In the detailed description, it can be clearly presented. In the manufacturing method of the present invention, the polarizing film of the iodine dyeing process is obtained by dyeing the polarizing film with an iodine dyeing process. The enamel dyeing treatment can be carried out by a conventional technique, for example, by immersing a polyvinyl alcohol (pvA) yt in an aqueous solution system containing iodine and iodide for dyeing, and optionally, by crosslinking with boric acid or borax or the like. The crosslinking is carried out in the bath of the agent, and then the uniaxial stretching step is performed, and the uniaxial stretching step can be carried out before, after or during the iodine dyeing. Preferably, the iodide is potassium iodide. The polarizing film can be Polyvinyl alcohol or saponified ethylene-vinyl acetate copolymer 201109746 film, in the preparation process can optionally be added to other monomers for copolymerization, such as unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated ~ acid In a specific example of the present invention, the polarizing film is polyvinyl hydrazine. The saponification degree of the polyvinyl alcohol is usually about 85 to 1 〇〇 mol%, preferably 疋 98 to 1 〇〇 mol. %. Further, the polyvinyl alcohol may be optionally further modified, for example, polyvinyl formal, polyvinyl acetal or the like obtained by modifying acetaldehyde with polyvinyl alcohol. The above iodine-dyed polarizing film was washed with pure water, followed by film drying. Preferably, the film drying temperature in the process of the present invention is between 35 and 50 ° C. Most preferably, the film is dried at a temperature of 4 〇〇c. Preferably, the temperature at which the bonding is dried in the process of the present invention is between 35 and 50 ° C. Most preferably, the temperature at which the bonding is dried is 40 〇c. In particular, the time during which the dual-temperature drying process of the method of the present invention is carried out may be different according to the conventional polarizing plate fabrication procedure, and the amount, material and characteristics of the polarizing film, the adhesive and the protective film used. Change. Preferably, the composition of the adhesive may be a mixture of a polyethylene glycol aqueous solution and a di-m-acid (such as oxalic acid, malonic acid, succinic acid, etc.) as a crosslinking agent, or a polyethylene glycol. a mixture of a main resin and an amine-based metal compound as a crosslinking agent. The adhesive can be further added according to conventional techniques, such as a crosslinking agent, a plasticizer, a stone singe coupling sword, and an anti-resistant agent. Electrostatic agent or particles. The application method of the adhesive can be carried out by any of the methods known in the art, such as a spray method or a knife coating method. In a specific embodiment of the present invention, the adhesive of the adhesive contains polyethylene lysate and cross-linking /, wherein 'the cross-linking agent is selected from a single „ (such as 曱路, μ or (4)), Two-way type (such as B-ply, propylene or tauric acid), diamines (such as ethylenediamine or hexamethylenediamine), epoxy compounds (such as ethylene glycol diglycidyl ether, dimethoate) Alcohol diglycidyl (6), transition metal (such as wrong, titanium, tungsten, iron, Ming or nickel ^ ' or a combination of these. '

The protective film used in the process of the present invention can be prepared by using various conventional materials, such as poly(tetra) polymers (such as polyethylene terephthalate, polyethyl phthalate, cellulose type polymers (such as diethyl fluorenyl). Cellulose, triethyl cellulose, acrylic polymer (such as poly-f-acrylic acid), styrene-based polymer (polystyrene, acrylonitrile-styrene copolymer), polycarbonate A vinegar-type poly-resin polyalkylene type polymer, a vinyl chloride type polymer, a quinone imine type polymer, a ring-diffuse hydrocarbon copolymer material. Among the above materials, in consideration of polarizing properties and durability, it is preferably utilized. The cellulose type polymer is more preferably prepared by using triethyl cellulose. In the specific embodiment of the present invention, the polarizing plate has two layers of m, wherein the protective layer is made of triacetyl cellulose. The other layer protective layer is made of a cycloolefin copolymer. The method for preparing the polarizing plate of the present invention can be changed according to the prior art, for example, applying a layer of an adhesive on the upper or lower surface or the two surfaces of the polarizing film, Then on the surface coated with the adhesive A layer of the protective layer (10) is formed to form the polarizing plate of the present invention, which comprises at least one polarizing layer, at least one protective layer, and an adhesive layer disposed between the polarizing layer and the protective layer. Preferably, the polarizing plate of the present invention Preferably, the absorption coefficient at a wavelength of 480 nm is between 3,500 and 4000 cm-1. Preferably, the absorption coefficient of the polarizing plate of the present invention at a wavelength of 6 〇〇 nm is between 3,500 and 4000 cm·1. The polarizing plate of the present invention has a degree of polarization of $99 995 Å. The thickness of the polarizing layer is not particularly limited, and is preferably about ι ΐ ΐ 5 卟 m. The thickness of the adhesive layer is not particularly limited, and is preferably 〇〇. 1~, more preferably 〇.〇1~2μΐη. The number of the bonding layers can be matched according to the required number of polarizing layers and protective layers. In the specific example, the polarizing plate has two layers of layers. The thickness of the protective layer is not particularly limited and is usually 5 to 200 μm, preferably 1 to 15 μm, more preferably 20 to 1 mm. When the protective layer is made of triacetyl cellulose When formed, the thickness of the protective layer is usually 20 to 200 μm, preferably 30~150μηι, more preferably 4〇~1〇〇μιη. The following examples will be further explained in the following examples, but it should be understood that the embodiments are for illustrative purposes only and should not be construed as DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the present invention is described in detail, it is to be noted that in the following description, similar elements are denoted by the same reference numerals. <Embodiment> Embodiments 1 to 3 will be based on The polarizing plate is prepared by the dual low temperature drying process listed in Table 1 below and the common method described below, and the polarizing plate obtained is as shown in FIG. 1. The polarizing plate i includes a polarizing layer u and a second layer of the layer 12 And two protective layers 13 and 14 : 10 201109746 [Common method of the embodiment] The polyvinyl alcohol having a thickness of 75 μm (average degree of polymerization: 17 〇〇, degree of saponification of 99.9% or more) is uniaxially stretched to a dry state. Size (length) is 5 to 6 times. The stretched film in the expanded state is immersed in (4) minus (according to the dish: mothing: water = 〇, 〇 5: 5: 100 by weight ratio) within 6 sec seconds, and then immersed in 65 C Boric acid treatment solution (according to potassium moth: boric acid: water = 2.5: 7 $. 100 weight 1 ratio modulation) within 3 sec seconds, then rinsed with 2 generations of pure water

In seconds, a polarizing film I U was produced, and a film drying process was carried out in a warm (four) 4 〇〇c pvA drying oven. The first and second sides of the polarizing layer U are coated with a polyethylene resin and a binder, wherein the crosslinking agent is selected from a single type (such as a light weight, a gamma acid) , two-way type (such as Ethylene, C2 or D-Road), transition metal (such as H, H, Co or recorded), or a combination of these, so that the upper and lower surfaces of the polarizing layer u are respectively An adhesive layer 12 is formed. Then, a layer of thickness (4) and a protective layer 13 composed of diethylaminocellulose and a layer of B layer 14 composed of a cyclic olefin copolymer are laminated on the two subsequent layers 12, respectively. In the bonding drying oven, the binding-bonding drying is performed to obtain the polarizing plate i as shown in the figure. Here, the temperature at which the bonding of Examples 1 and 2 was dried was 4 〇〇 c, and the temperature at which the bonding of Example 3 was dried was Huan. The above temperature control conditions for drying are as listed.

[Comparative Examples 1 to 3J &gt; In addition to the temperature control conditions for film drying of the gauge 11 and the temperature control conditions for bonding and drying after bonding the D 蒦 film 13 14 , 201109746 polarizing plate! The rest of the production stream. Among them, the film of the comparative example... The common method of the same method is that the film has a dry temperature of 5 〇〇c, and the film drying temperature is 5 〇〇C segment by section in the Ganzidao time of the dry welding 2 2 (50 -70. 〇, Comparative Example 3 夕 2』 You are upgrading to 70γ ratio (10)3 &lt; phase drying 5〇°C step by step to 95: in the dry time C), and the drying temperature of the comparative example Actual (10) &quot; identical, I: dry welding of each comparative example. The items are also listed in Table i. J wandering around the temperature control bar Table 1·

The above examples and comparative examples were respectively subjected to the following tests, and the results obtained are shown in Table 2: 1. Absorption coefficient: The test was carried out by using an ultraviolet light absorber (manufactured by Shimadzu Corporation, Japan, model number UV-2450). Since I3--PVA and I5--PVA produce characteristic absorption near the wavelengths of 480 nm and 600 nm, respectively, the absorbance (A48Qnm, A600nm) of each group of polarizing plates measured at a specific wavelength position can be converted by the formula of Beer's law. The absorption coefficient (ousGnm) of each group of polarizing plates at 480 nm and the absorption coefficient (a6〇〇nm) at 600 nm were calculated. 12 201109746

2. CIE Chroma: The standard used by the international commission on illumination (CIE) to define a CIE α* ό* (CIELAB) color space with three basic coordinates (ΖΛ α*, 6*) indicates the brightness of the color (Z*: 1*=0 indicates black, and Ζ*=100 indicates white), and the position of the color between red and green (α* is a negative value indicating green, and positive The value indicates a trend toward red) and the color is between yellow and blue (b* negative values indicate a trend toward blue, while positive values indicate a trend toward yellow). The present invention uses a luminometer (manufactured by JASCO Corporation, model number V-7100) to test the hue values of the hue exhibited by each set of polarizing plates. 3. Polarization: The test was carried out using a luminometer (manufactured by Sakamoto Seiko Co., Ltd., model number V-7100). The general industry expects a degree of polarization of 2 99.990%. 4. Contrast: The contrast value of the polarizing plate was measured using the Rapid View Character Meter (ELDIM EZ-CONTRAST). Table 2_ Absorption Coefficient Absorption Coefficient CIE Chromaticity Contrast Polarity 80 nm ^ 600 nm a* b* Example 1 3726 3779 -0.77 2.92 3104 99.997 Example 2 3701 3752 -0.75 2.92 3094 99.997 Example 3 3594 3713 -1.32 3.17 2836 99.996 Example 1 3560 3648 -1.38 3.42 2766 99.995 Comparative Example 2 3478 3506 -1.36 3.55 2661 99.993 Comparative Example 3 3479 3474 -1.47 3.61 2671 99.993 From the results of Table 1, it can be seen that the method of the present invention reduces the processing temperature of film drying and conformation drying. The absorption coefficient values of the polarizing plates of Examples 1 to 3 at wavelengths of 480 nm and 600 nm were significantly increased with respect to the values of 13 201109746 measured by the polarizing plates of Comparative Examples 1 to 3 'this result demonstrates the drying procedure of the dual low temperature. The balance between v_pvA and ιΓ_ρν error compound in the PVA film can be effectively controlled to improve the binding stability and adsorption amount of the cerium ion in PVA. From the results of the polarizing plate test of Example 3 and Comparative Example 3, it can be seen that under the same bonding and drying conditions, when the drying temperature of the pvA film after dyeing is lowered, the suction line value (ua_nm) decreases with temperature. Obviously, and through the film drying process of Example 3, the polarizing degree of the polarizing plate can be effectively increased to 99996%, and the measured contrast value is also significantly increased. Next, from the results of the polarizing plate tests of Examples 1 to 3, it was found that the same film drying conditions (temperature was 4 Torr. When the bonding drying temperature was lowered, the absorption coefficient values (a48Qnm and %(9) nm) also correlated with the temperature. The decrease is obviously improved, and the comparison of Examples 1 and 2 jumps to the measured value of 3000 or more, and the two chromaticity values (a* and b*) of the color system obviously tend to be neutral hue, which proves that the regulation is further regulated. The drying temperature can make the structure and balance of PVA and polyiodide ions more optimal, and also significantly improve the hue of the polarizing plate, and obtain a polarizing plate with more uniform color and balanced absorption in the visible light field. According to the method of manufacturing the polarizing plate of the present invention, the double-low temperature drying process effectively adjusts the balance of the polyiodide ions in the polarizing plate and the stability of the combination, and can improve the hue and absorbance of the polarizing plate and significantly increase the degree of polarization and contrast. In order to achieve the so-called high performance polarizing plate in the industry, the above description is only a preferred embodiment of the present invention, and the scope of the present invention cannot be limited thereto, that is, according to the present invention. Please patent 14201109746

The scope of the invention and the equivalent equivalents and modifications of the invention are still within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of a specific example of a polarizing plate of the present invention. 15 201109746 [Description of main component symbols] 1...... ..... polarizing plate 13-.... ••...A protective layer 11........polarizing layer 1 /j * . , ..., * B protective layer 12**-·- :. ...the next layer

16

Claims (1)

201109746 VII. Patent application scope: ι_ A method for preparing a polarizing plate, comprising: drying a thin film of a polarizing film treated by a dish at a temperature between 25 and 50 ° C; and drying the film After at least one side of the polarizing film is bonded to the protective film with an adhesive, the temperature is between 25 and 55. (: performing a dry-drying process to obtain a polarizing plate comprising a polarizing layer, at least one protective layer, and at least one adhesive layer disposed between the polarizing layer and the protective layer. The method for producing a polarizing plate according to the first aspect, wherein the drying temperature of the film is between 35 and 50 ° C. 3. The method for producing a polarizing plate according to claim 2, wherein the film The drying temperature is 40 〇 C. 4. The method for producing a polarizing plate according to claim 1, wherein the temperature of the bonding drying is between 35 and 50 ° C. The method for producing a polarizing plate according to the item 4, wherein the temperature of the bonding and drying is 4 〇. (6) The method for producing a polarizing plate according to the above-mentioned claim, wherein the polarizing film is utilized The method for preparing a polarizing plate according to the first aspect of the invention, wherein the squirrel moth dyeing process is an aqueous solution system containing iodine and iodide for performing a dyeing process for a polarizing film. 8. According to the patent application The method for producing a polarizing plate according to Item 7, wherein the etchant is deuterated. 9. A polarizing plate </ RTI> comprising a polarizing layer, at least one protective layer, and at least one layer of 201109746, wherein the layer is The polarizing plate is disposed between the polarizing layer and the protective layer, and the absorption coefficient of the polarizing plate at a wavelength of 480 nm is between 3000 and 4000°: 111-1, and the absorption coefficient at a wavelength of 600 nm is between 3000 and 4000 cm1. 10. The polarizing plate according to claim 9, wherein the polarizing plate has an absorption coefficient at a wavelength of 480 nm of between 3500 and 4000 cm_1. U. The polarized light according to claim 9 The plate, wherein the polarizing plate has an absorption coefficient at a wavelength of 600 nm of between 3500 and 4000 cm-1, and the polarizing plate of the polarizing plate according to claim 9 has a degree of polarization of 99.995%. The polarizing plate of claim 9, wherein the polarizing layer is prepared by using polyvinyl alcohol. 14. The partial yarn according to claim 9, wherein the protective layer is utilized. Select from diethyl bismuth fiber Biotin or prepared cycloolefin copolymer obtained. 18