TW201144362A - Method for preparing polarizer - Google Patents

Abstract

Disclosed is a method for preparation of a polarizer, more particularly, a method for preparing a polarizer, including; primary cross-linking conducted using an inorganic cross-linking agent, and secondary cross-linking conducted using an organic cross-linking agent, so as to effectively reinforce cross-linking reaction, to thereby obtain a polarizer having various advantages including, for example, excellent optical properties, prevention of film rupture and wrinkling, enlarged area and reduced thickness, high size stability in longitudinal and transversal directions, or the like. The disclosed method may attain process handling and production efficiency.

Description

201144362 VI. INSTRUCTIONS OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention is directed to polarizers having optical properties and other advantages, such as preventing film cracking and wrinkling, increasing area and reducing thickness, height, qualitative, and the like. And methods for improving process processing and production efficiency = [Prior Art] For improvement such as LCD, electric excitation #, monthly sm electric Kaizan (EL) display device, plasma display panel (PDP), field emission display (FED) ) The color reproduction and brightness of images of various image display devices, etc., are concentrated on polarizers. In particular, with the rapid use of such image display devices in various aspects, the demand for polarizers having an increased area and a reduced thickness has also increased. Therefore, because of the various environments (4), dimensional stability under different endurance conditions is important to ensure product reliability. Usually, the polarizer is produced by expanding a polymer film such as a polyethylene glycol (pVA) film by one color, crosslinking, stretching, and washing. Crosslinking in this respect is usually carried out using an inorganic crosslinking agent such as a boron compound. However, the use of only such an inorganic crosslinking agent results in the formation of a short crosslinked chain, resulting in an increase in the deep concave cause: stretching. As a result, the thickness of the polarizer is increased, and the width is narrowed, resulting in film rupture. Furthermore, the above techniques cause other disadvantages such as poor dimensional stability under high heat cattle, poor productivity, and the like. To solve the above problems, it is proposed to use an organic crosslinking agent and a boron compound. This franchise is open to H06-235815. The use of the blended compound is 201144362 '-,,,,', and since the aldehyde group is reduced and oxidized in the air, it is difficult to ensure the dimensional stability of the cross-linking. Further, the above technique is difficult to manufacture a polarizer due to the unique (pungent) odor of the brewing. SUMMARY OF THE INVENTION The object of the present invention is to provide a method for producing a polarizer having various advantages such as excellent optical properties, prevention of film breakage and wrinkles, increase in thickness, reduction in thickness, and size of both longitudinal and transverse directions. Stability and so on. The moon is also a manufacturing method for providing a polarizer having stability and improved production efficiency. Further, another object of the present invention is to provide a polarizing plate ' having a polarizing plate manufactured by the above method and an image display device having the above polarizing plate. The present inventors conducted intensive and extensive research to solve conventional problems, for example, a boron compound as a standard crosslinking agent can increase the thickness of the polarizer and reduce the width to cause film breakage and break dimensional stability; The dimensional stability of the transverse direction, the pungent odor of the organic crosslinking agent, and the like are ensured. In this respect, short cross-linking chains and rigidity can be applied in the main cross-linking using a boron compound to suppress film sensitization, thereby improving the treatment and forming iodine orientation, using a linear polycarboxylic acid compound (at least two carboxyl groups). The secondary cross-linking structure can form a stable cross-linking structure to impart flexibility and stretchability to the film, thereby overcoming the above problems. Thus the present invention has been completed. Accordingly, the present invention provides a method for producing a polarizer comprising: immersing a polyvinyl alcohol film in a main cross-linking solution containing a boron compound, and crosslinking the polyvinyl alcohol film with at least two carboxyl groups. Secondary cross-linking by a secondary cross-linking solution of a linear poly-retensive acid compound. The boron compound may contain 1 to 10 wt.% with respect to 100 Wt.% of the main crosslinking solution. The linear polycarboxylic acid compound having at least two carboxyl groups may be selected from the group consisting of succinic acid, glutaric acid, adipic acid, oxalic acid, Tartaric acid, citric acid, i, 2, 3, 4-butylene tetracarboxylic acid, and derivatives thereof. A linear polycarboxylic acid compound having at least two carboxyl groups relative to 100 Wt. The secondary cross-linking solution may contain 〇丨 to 1 〇 wt %. The secondary crosslinking solution may further contain 10 parts by weight or less of the boron compound based on the weight of the linear polycarboxylic acid compound. Secondary cross-linking can be carried out after the main cross-linking, or the main cross-linking can be carried out after the secondary cross-linking. Major cross-linking, secondary cross-linking, or major and minor cross-linking processes can be repeated at least twice. The present invention provides a coupling polarizing plate which is produced by laminating a protective film on at least one side of the above-mentioned polarizer. The polarizing plate may further comprise at least a compensation film, a viewing angle compensation film, and a brightness enhancement film laminated on the polarizer protective film. The present invention provides an image display device provided on a polarizing plate. According to the present invention, as described above, the crosslinking reaction using the inorganic and organic crosslinking agents can be effectively strengthened to increase the (4) fixing efficiency as a dichroic polarizing material, thereby enhancing optical properties and preventing film breakage. Therefore, the present invention can provide a lens that has excellent durability and exhibits improved flexibility and stretchability to prevent film wrinkles. The present invention can also increase the area and reduce the thickness of the polarizer while improving the dimensional stability in the longitudinal and lateral directions. In addition, the present invention can provide a polarizer manufactured by Angong Cheng, which is capable of processing and production efficiency. [Embodiment] According to the present invention, there is provided a method for producing a polarizer which has various advantages such as excellent optical properties, large area, reduced thickness, dimensional stability, reduced film breakage and wrinkles, and can improve process processing and production efficiency. Hereinafter, the present invention will be described in more detail. The method for producing a polarizer according to the present invention may comprise: immersing a polyethylene glycol film in a main cross-linking solution containing a main crosslinking solution of a boron compound; and immersing the polyvinyl alcohol film in a linear polycarboxylate containing at least two carboxyl groups Secondary cross-linking by the secondary cross-linking solution of the acid compound. According to the invention, the polarizer is a general iodine polarizer comprising a polymer film and iodine. The polymer film used to make the polarizer may include, but is not limited to, any film that can be dyed with iodine. Specific examples of the polymer film may include: a polyethylene glycol film and/or a partially saponified polyvinyl alcohol film; a hydrophilic polymer film such as a polyethylene terephthalate film, an ethylene-vinyl acetate copolymer film, ethylene- A vinyl alcohol copolymer film, a cellulose film, and a partially saponified film thereof; a polyolefin-oriented film such as a dehydrated polyvinyl alcohol film, a degassed polyvinyl alcohol film, or the like. Among them, it is preferable to use a polyvinyl alcohol film to effectively enhance the uniformity of the degree of polarization and to exhibit excellent 6 201144362 iodine dye affinity. According to the conventional technique, the manufacturing method of the polarizer includes expansion, dyeing, crosslinking, stretching, washing, and drying processes. Such manufacturing methods are generally classified according to the type of the stretching process. For example, a dry draw process, a wet draw process, or a combination thereof (i.e., a hybrid draw process) can be representative of the draw process. The wet drawing process for the method of manufacturing a polarizer according to an embodiment of the present invention will be explained below. In addition to drying, other processes can be carried out in a constant temperature water bath in which at least one different solution is placed and the polyvinyl alcohol film is soaked. The order and/or the number of repetitions of each process are not particularly limited. That is, each process can be performed simultaneously or sequentially. In addition, some processes can be omitted. For example, stretching can be performed before or after dyeing, or simultaneously with swelling or dyeing. Before dyeing, the unstretched polyvinyl alcohol film may be immersed in an expansion tank containing an expansion solution to perform an expansion process to remove impurities such as anti-blocking agents or dust accumulated on the surface of the film while expanding the polyvinyl alcohol film. In order to improve the stretching efficiency, to prevent irregular dyeing, and ultimately improve the physical properties of the polarizer.膨胀 The swelling solution used here may be water (purified water, deionized water), and may further contain a small amount of glycerin or hydrazine to expand the polymer film and improve workability. In this case, the glycerin content may be 5 wt.% or less with respect to 1% by weight of the swelling solution. Similarly, the oxime release content may be 10 wt.% or less with respect to the swelling solution. The expansion tank temperature used herein may range from 2 Torr to 45, 25 to 4 Torr.匚 The period of expansion (the immersion time in the expansion tank) can be 18 〇 or less, and 201144362 is better than 9 sec. If the impregnation time is within this range, over-expansion which causes film saturation can be suppressed. As a result, the polyvinyl alcohol film was prevented from softening and cracking. In addition, iodine can be uniformly adsorbed, thus increasing the degree of polarization. Stretching can be carried out during expansion, in which case the draw ratio can be about 3.5 times. 1 Expansion can be omitted or performed simultaneously with dyeing. The dyeing is a process in which a polyethylene film is immersed in a dyeing tank filled with a dyeing solution containing a dichroic material (e.g., iodine) to suck the moth into the polyethylene glycol film. The hydrazine is added to water, an organic solvent or a mixture thereof to prepare a dyeing solution.

The dyeing solution of the moth content may be 0.4 to 400 mm 〇 1 /L, and 0.8 to 275 mmol / L is better, 1 5 , ΛΛ " preferably 1 to 200. To improve the efficiency, the telluride can be further added as a co-solvent to the dyeing solution. Such moth compounds may include potassium hydride, hardening clock, sodium iodide, zinc telluride, bumping Mingsu = wrong, copper sulphate, moth sputum, sputum, src, and moth titanium Use or combine two or more. Among them, it is best to use a 3 degree high break in water (4). The dyeing solution may have a dyeing solution of 0.01 to 1 〇 wt.%' 〇1 〇〇 to 5 wt%, more preferably _wt.%. The degree can be 5 to 42t, and 1〇 to the pit is better. Polyethylene. The immersion time of the smear into the dyeing tank may be 1 to 20 minutes, and 2 to 1 Torr is better. The stretching can be carried out at the time of dyeing. β 芬Λ η In this case, the cumulative stretching ratio may be from 1 · 1 to 4·〇. Here, the "accumulated stretching b, multiplying the obtained I represents the stretching ratio cross-linking in each process is to immerse the film in the cross-linking solution to fix the adsorbed antimony molecule to the 8 201144362 dyed polyvinyl alcohol film. , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Hard molecules often dissolve or sublimate with the environment. Therefore, the four crosslinks must be fully performed. In addition, in order to position the knives at the gate of the polyvinyl alcohol molecule and to improve its optical properties, the stretching must be carried out during crosslinking. The highest draw ratio, that is, the cross-linking process is important. The present invention may comprise at least a parent-link of the grade - W Μ ΛΛ - in particular, the main cross-linking solution containing an inorganic cross-linking agent may be supplied to the company.士.Α ^ is used for the main couplet, and the human cross-linking solution containing the organic cross-linking agent can be used for secondary cross-linking.

The main parent association can use the main cross-linking solution of the phlegm-g-compound as a chelating agent, and the short-crossing film wrinkles made by the Μ 合 合 , , , , , , , , 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高 提高Therefore, the cross-linking solution may include water as a solvent and a compound such as ·::(d). The main crosslinking solution may further comprise an organic solvent compatible with water. >4曰♦ The main compound content of the side compound relative to 1% is 1%, and 2% to 6wt.% is better. ^ When the boron compound content is less than 1 wt 0 / 〇, the cross-linking effect of the boron compound will decrease to θ 擗 to impart rigidity. When the amount of 3 is more than 1 〇 wt. %, the helmet machine will take over the Shushi ‘,, the machine coupling agent will make too much cross-linking, so it is difficult to effectively cross-link by the organic crosslinking agent. The secondary cross-linking can use a secondary cross-linking solution as a cross-linking agent, and includes a linear poly-retensive acid compound having two carboxyl groups, whereby the film is effectively stretched to form a stable crosslinked structure. 〇 ^ The secondary cross-linking solution may include water as a solvent and a linear polycarboxylic acid compound having at least two 201144362 carboxyl groups. The secondary crosslinking solution may further comprise an organic solvent compatible with water. At least two carboxyl groups -------------- the alcohol film is stable crosslinked without structural problems, while imparting better flexibility and stretchability. Examples of the above polylabeled acid compound may include, but are not limited to, oleic acid, glutaric acid, adipic acid, oxalic acid, sprinkle xI4. ^ phthalic acid, citric acid, 1,2,3,4-butyltetracarboxylic acid Acid (main/representative by the following Chemical Formulas 1 to 7)' and its derivatives. It is best to use a few acid compounds and install <, -& The above compounds may be used alone or in combination of two or more. Alone made [Chemical Formula 1] 0 HO person, γ0Η 0 [Chemical Formula 2] 〇 0

HO people 'eight ^ OH

[Chemical Formula 3] 201144362 [Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

Ο OH 〇 HO

OH Ο^ΌΗ [Chemical Formula 7]

The content of the linear polycarboxylic acid compound having at least two carboxyl groups may be from 0.1 to 10 wt.% with respect to 100 Wt.% of the secondary crosslinking solution. In view of economic efficiency, ease of control of the process, and/or dimensional stability, the above content is preferably 0.5 to 6 wt.%, preferably 55 to 3 wt.%, relative to 100 wt.% of the secondary crosslinking solution. When the right content is less than 〇 · 丨 wt %, the crosslinking effect of the organic crosslinking agent may be very slight', thus making it difficult to impart flexibility to 1 & When the content exceeds 10 wt.%, the organic crosslinking agent will have too much blister + ping, thus destroying dimensional stability and film wrinkle suppression 201144362. A linear polycarboxylic acid compound having at least two carboxyl groups may be bonded to the boron compound. The linear polyphenolic compound having a butterfly compound content of at least two carboxyl groups relative to the weight of the oxime may be 1 part by weight or less, more preferably 7 parts by weight or less. When the content of the right boron compound exceeds i 0 wt%, the effect of the organic crosslinking agent is destroyed, and the treatment stress is increased to cause film breakage and/or wrinkles. The primary and secondary cross-linking solutions may each further contain a small amount of iodine to ensure uniform polarization within the polarizer while preventing desorption of dyed iodine. This iodide can be the same as that used for the dyeing process, and its content is relative to 100.

The Wt.% primary or secondary crosslinking solution may be from 0.05 to 15 Wt.%, preferably from 0.5 to 11 wt.%. The dipping time can be from 1 second to 15 minutes, and more preferably from 5 seconds to 10 minutes. Cross-J to cross-link, secondary cross-linking, and/or primary cross-linking and secondary cross-linking. Primary and secondary cross-linking process restrictions. For example, - moxibustion treatment _ π 丄 people jin Wo special primary cross-linking after cross-linking, or vice versa, ^ trajectory in secondary delivery. Furthermore, the implementation of the 'cross-linking can be broken in any order.../the process of the secondary/main* 7-order ordering' such as major/minor/primary, human and/or major/minor/main/ Stretching is possible when the secondary cross-linking system cross-links. In this situation: A cumulative draw ratio of 8.0 times. A 仃 仃 to 3.0 = the above 'stretching can be in the expansion, dyeing and / or cross-linking 另 using another - Latin filled with stretching solution. Otherwise stretch the process. Long and joint after another 12 201144362 cleaning is a process of immersing the fully crosslinked and stretched polyvinyl alcohol film in a cleaning tank containing a cleaning solution to remove unwanted residues adhering to the polyethylene glycol film, such as a shed. acid. The cleaning solution can be water' to add moth compounds. The temperature of the cleaning solution can be from 10 to 60 t, more preferably from 15 to 4 Torr. The slight cleaning may be performed at least once each time the previous process such as stretching is performed or the cleaning may be repeated at least once, and the repeated cleaning is not particularly limited. Drying is a process of drying the cleaned polyethylene film and improving the orientation of the dyed ruthenium molecule, thereby producing a polarizer having excellent optical properties. Drying can include natural drying, air drying, heating, far infrared drying, microwave drying, hot air drying, and the like. Although drying with hot air is generally used, microwave drying to activate moisture contained in the film has recently increased. For example, 'hot air dry material is 1 to H in 2G to (4). The drying temperature can be relatively low to prevent damage to the polarizer, preferably 8 〇t or less, and preferably 60 t or less. As described above, the polarizing plate manufacturing method of the present invention adopts the main crosslinking using an inorganic crosslinking agent and the secondary crosslinking using an organic crosslinking agent to effectively strengthen the crosslinking reaction, thereby increasing the fixation of iodine as a dichroic material. effectiveness. As a result, various advantages such as excellent optical properties, prevention of film breakage, improvement of film flexibility and stretchability, suppression of wrinkles, and the like can be attained, whereby a modified process-processed polarizer is finally obtained. Further, the produced polarizer can have an area and a reduced thickness, and it is preferable to exhibit longitudinal and lateral directions while producing with improved productivity. The present invention provides a polarizer produced in accordance with the above manufacturing method. 13 201144362 The present invention also provides a polarizing plate having a polarizer and a protective film laminated on at least one side of the polarizer. Such a protective film may have appropriate transparency, mechanical strength, thermal stability, moisture resistance, omnidirectionality and the like. In detail, the 'protective film can be prepared using a thermoplastic resin' includes, for example, a polyester resin such as polyethylene terephthalate vinegar, polyhexaphthalic acid vinegar, polybutylene terephthalic acid, and the like; Cellulose resin, such as cellulose diacetate, cellulose triacetate, etc.; polycarbonate resin; acrylic resin such as decyl methacrylate, polyethyl propyl acrylate, etc.; styrene resin, such as poly Stupid ethylene, acrylonitrile-styrene copolymer 4, etc., polyolefin resin such as polyethylene, polypropylene, cyclic polyolefin or polyolefin with norbornene structure, ethylene-propylene copolymer, etc.; Month S, poly-branched amine resin, such as nylon, aromatic polyamidamine; melamine resin; polyacetal resin; oxime resin; polyether ketone resin; polyphenylene sulfide resin; vinyl alcohol resin; ; vinyl butyral resin; allylated resin; polyacetal resin; cyclic oxime resin and the like. The film can be formed using a mixture of at least one of the above thermoplastic resins. Further, the film may be formed using a thermosetting resin such as methyl acrylate, polyurethane, epoxy, hydrazine or the like or an ultraviolet curable resin. Among them, in view of polarized light and/or durability, it is preferred to use a cellulose film whose surface is saponified with an alkaline material. Further, the protective film can also be used as the optical layer. In the present invention, the polarizing plate is not particularly limited in structure, and a different type of optical which satisfies the desired optical properties can be laminated on the polarizing plate. Examples of such a structure may include: a laminate structure in which a protective film is laminated on at least one side of the polarizer to protect the polarizer; such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion-proof layer 201144362, an anti-glare layer, or the like. The surface treatment is laminated on at least the side of the protective film or the polarizer; the alignment liquid crystal layer or any other functional film is laminated on the protective film or the laminated structure on at least one side of the polarizer, and the like. Furthermore, the laminated structure comprises at least one optical layer selected from the group consisting of: an optical film such as a polarizing converter: a reflector; a transflector; and a wave plate (including a λ plate) such as a half-wave plate or a quarter-wave plate. A phase retardation plate; a viewing angle compensation film; a brightness enhancement film generally used to manufacture various image display devices. In detail, examples of the polarizing plate in which the protective film is laminated on one side of the polarizing plate may include a reflective polarizing plate or a translucent polarizing plate including a reflector or a semi-transparent reflector stacked on the protective film; A circular or circular polarizing plate of the retardation plate; a wide viewing angle type polarizing plate including a viewing angle compensation layer or film; a polarizing plate including a brightness enhancement film, and the like. The polarizing plate described above can be used for various image display devices, and includes an EL display device, a PDP, and an FED in addition to a typical LCD. Hereinafter, preferred embodiments will be described with reference to examples and comparative examples to better understand the present invention. However, it will be apparent to those skilled in the art that the present invention may be modified and modified without departing from the scope of the invention. in. Example Example 1 99.9 ° /. The above saponified transparent unstretched polyvinyl alcohol film (VF-PS, Kuraray Chemical Co. Ltd.) was immersed in water at 30 ° C (from 15 201144362 water) for 2 minutes to expand. After the wetting and swelling as described above, the treated film was immersed in a dyeing solution containing 3.5 mmol/L of broken and 2 wt.% of antimony telluride at 30 ° C for 4 minutes for dyeing. Here, the film was stretched to 1.3 times and 1.4 times, respectively, during the expansion and dyeing processes. Next, the dyed film was immersed in a main crosslinking solution containing 10 wt.% of potassium iodide and 3.5 wt.% of boric acid at 50 ° C for 2 minutes (main crosslinking stage), and then immersed at 50 ° C to contain 10 wt.%. A secondary crosslinking solution of potassium iodide, 3.5 wt.% of boric acid, and 1 wt.% of glutaric acid (secondary crosslinking stage) is used for the crosslinking reaction. Here, the treated film was stretched to 2.5 times and 1.5 times, respectively, in the primary and secondary crosslinking stages. As a result, the total cumulative draw ratio reached 6.8 times. After completion of the crosslinking, the formed film was dried in an oven at 70 ° C for 4 minutes, thereby obtaining a polarizer. A cellulose triacetate (TAC) film was laminated on both sides of the prepared polarizer to prepare a polarizing plate. Example 2 The same procedure as in Example 1 was repeated except that the secondary crosslinking solution contained 3 wt.% of glutaric acid. Example 3 The same procedure as in Example 1 was repeated except that the secondary cross-linking solution contained 6 wt.% of glutaric acid. Example 4 The same procedure as in Example 1 was repeated except that the secondary cross-linking solution contained 9 wt.% of pentane. acid. Example 5 The same procedure as in Example 1 was repeated except that the secondary cross-linking solution contained hexamethylene 201144362 acid instead of hydrazine acid. Example 6 The same cardiac sequence of Example 1 was repeated except that the secondary cross-linking solution contained rubic acid instead of glutaric acid. Example 7 The same procedure as in column 1 was repeated except that the secondary cross-linking solution contained 1,2,3,4-butanetetracarboxylic acid instead of glutaric acid. Example 8 The same procedure as in Example 1 was repeated except that the film was stretched to 1.5 times and 2.5 times, respectively, in the primary and secondary cross-linking stages. Example 9 The same procedure as in Example 1 was repeated except that the main cross-linking was carried out after the secondary cross-linking. Example 10 Repeat the same procedure as in Example 1, except that in the secondary cross-linking (secondary cross-linking stage), a secondary cross-linking containing 5 G ° C of moth potassium and 3 wt % of glutaric acid was used. For the solution, the film was stretched to 2.5 and 1.5 times, respectively, during the primary and secondary crosslinking stages. Comparative Example 1 The same procedure as in Example 1 was repeated except that the secondary crosslinking solution contained ethanedioic acid instead of glutaric acid. Comparative Example 2 The same procedure as in Example 1 was repeated, and the cross-linking ratio was 4.0 times. In addition to only the main cross-linking, there is no time. 17 201144362 Comparative Example 3 The same procedure as in Example 1 The cross-linking ratio was 4.0 times. 'Operation: owing to cross-linking without major comparative poverty 4 Repeat the same procedure of Example 1, except 咏ί, for secondary cross-linking without major cross-linking, using 10 wt·% potassium iodide and 3 wt A secondary crosslinking solution of % glutaric acid having a draw ratio of 4.0 times. Table 1

The case is mainly cross-linked by cross-linking -- is Bora is a poly-hectoric acid compound (wt.0/〇) Boron-Brazil / Refining / pentyl butyl butylation _ 丨 _ Stretching no ratio than di- cimol Aldehyde (acidic acid tetraester (wt. (times) (W carboxy (wt. %) t.) acid%) %) __" Example 1 Y 3.5 2.5 Y 1 - 3.5 - Example 2 Y 3.5 2.5 Y 3 - - 3.5 - Example 3 Y 3.5 2.5 Y 6 • - 3.5 - 1.5 ------ Example 4 Y 3.5 1.5 Y 9 - - • 3.5 Example 5 Y 3.5 2.5 Y - 1 - 3.5 - 1.5 Example 1 Y 3.5 3.0 Y - - 1 Unloading - 1.25 Example 7 Y 3.5 2.5 Y - - - 1 3.5 - 1.5 Example 8 Y 3.5 1.5 Y 1 - - • 3.5 - 2.5 - an example 9 Y 3.5 2.5 Y 1 - - • 3.5 - 1.5 ·—An example Y 3.5 2.5 Y 3 _ • - - 1.5 10 Comparative example 1 Y 3.5 2.5 Y - 3.5 1 1.5 Comparison Y 3.5 3.8 N - - - - - - -4.0 ----J 18 201144362

Experimental Examples For the polarizers manufactured in the above examples and comparative examples, the results of measurement of physical properties according to the following procedure are shown in Table 2 below. 1. Optical properties (polarization, transmittance) Each of the polarizers prepared was cut into a size of 4 cm x 4 cm, and then an optical property was measured using an ultraviolet light-visible spectrometer (V_7100, JASC〇 c〇 ). The transmittance can be calculated by the following Equation 1. (Equation 1) Degree of polarization (P) = [Q2] ] 1/2 (T1+T2) where Τι represents the parallel transmittance of a pair of polarizers such that their absorption axes are parallel to each other; Representation - the vertical transmittance obtained when the polarizers are aligned such that their absorption axes are perpendicular to each other. 2. Thickness (/ΛΠ) Using a film thickness measuring instrument (MS_5c, Nikon), the thickness of each polarizer was measured at 10 points in the width direction, and the average value of the measured thickness was taken. 3. Deep recess ratio (%) This factor represents the ratio of the width of the polarizer to the initial dish width of the polyvinyl alcohol film 19 201144362. Then, the deep recess ratio is calculated according to the following Equation 2. (Equation 2) Deep concave ratio _θ^2) χ 100 (L〇 where L| represents the initial dish width of the unstretched polyvinyl alcohol film, and L2 represents the width of the produced polarizer.) 4. Dimensional stability After the polarizer is cut into the size of lCmx3Cm in the longitudinal direction (width: TD) and the lateral direction (length: MD), the cut sample is left at 80 C for 24 hours under heat-proof conditions. The sample is measured by a two-dimensional measuring instrument. The dimensions before and after the heat protection condition are then calculated according to the following Equation 3 (sometimes referred to as 'dimensional stability,) (%). (Equation 3) Dimensional change (%) = Wxl 〇 ° where Pi represents The initial length of the polarizer 'P2 is the length of the polarizer after being placed under heat-proof conditions. 5. Tensile strength (MPa) After rolling, the polyethylene film is stretched in the cross-linking groove to reach the final cumulative stretch ratio. And the tensile strength of the polyvinyl alcohol film before drying is 201144362. If the tensile strength is above 1 OMPa, the film is considered to have a high risk of rupture. 6. Wrinkle evaluation after the father's joint and before drying 'visually treated poly Whether the dilute alcohol film is sensitive. 7. Cross-linking confirmation is confirmed Whether the polarizer is cross-linked, a spectrometer (FT_IR) is used to analyze the polarizer dissolved in hot water, and the C = 〇 peak is generated near 1700 to 1720 cm.1. Table 2 Example - Optical Properties Thickness (/ΛΠ) Deep Concave ratio (%) Dimensional stability (%) Processability cross-linking polarization (%) Transmittance (%) MD TM Tensile strength (MPa) Wrinkle C = 0 Peak case 1 ^99.996 41.9 23 51.1 1.2 3.1 8 No Yes 99.996 42.4 21 50.4 1.3 3.3 6 No Yes 3 99.994 42.2 20 49.0 1.4 3.2 5 No Yes 5 _99.993 41.5 18 47.5 1.4 3.0 4 No Yes 99.997 42.1 22 50.9 1.2 2.9 8 No Yes Example lo ^--- Compare 2 _99 .996 41.8 25 51.9 1.3 3.0 7 No Yes _99.996 42 25 53 1.3 3.0 8 No Yes _99.997 42.6 19 49.1 1.3 3.0 7 No Yes _99.996 42.8 18 48.9 1.4 3.0 6 No Yes 99.993 43.1 17 46.5 1.5 3.1 4 No Yes 99.995 40.8 30 59.7 1.5 4.5 14 Yes No 99.996 41.1 32 60.6 1.9 3.8 15 Yes No 21 201144362 Comparative example 3 99.996 41.9 20 49.4 2.0 4.2 11 Yes Yes Comparison example 4 99.996 42.5 18 49.0 2.5 4.5 6 Yes Yes As shown in Table 2 above, Compared to Comparative Examples 1 to 4 Polarizers, which are effective cross-linking of polarizers made according to Examples 1 to 1 of the present method, include the primary cross-linking using rotten compounds and the secondary cross-linking of linear polycarboxylic acid compounds using at least two carboxyl groups. It has excellent optical properties. In addition, these polarizers have no film cracking and wrinkles, thus achieving better process processing and excellent dimensional stability in the machine direction and in the cross direction. While the invention has been described with reference to the preferred embodiments, various modifications and changes may be made. The invention is invented, but is familiar with the skilled person. It is not defined by the scope of the patent application. [Simple description of the schema] Benefits», [Key symbol description] Benefit 22

Claims (1)

201144362 ' VII. Patent application scope: 1. A method for manufacturing a polarizer, comprising: immersing a polyvinyl alcohol film in a main cross-linking solution containing a compound to carry out main cross-linking; and immersing the polyvinyl alcohol film in at least Secondary cross-linking of a secondary cross-linking solution of a linear polycarboxylic acid compound of two carboxyl groups. 2. The method according to item ith of the claim patent wherein the boron compound content is from i to 10 wt% with respect to 100 wt.% of the main crosslinking solution. 3. The method according to the invention of claim 2, wherein the linear polycarboxylic acid compound having at least two carboxyl groups is selected from the group consisting of succinic acid, glutaric acid, adipic acid, oxalic acid, tartaric acid, citric acid, hydrazine, 2, At least one of the group consisting of 3,4-butanetetracarboxylic acid, and a derivative thereof. 4. The method according to the invention of claim 2, wherein the content of the linear polycarboxylic acid compound having at least two carboxyl groups is 0.1 to 1 〇 wt 0 / with respect to 100 wt.% of the secondary crosslinking solution. . 5. The method of claim 2, wherein the secondary crosslinking solution further comprises 10 parts by weight or less of the boron compound relative to 1 part by weight of the linear polycarboxylic acid compound having at least two carboxyl groups. 6. According to the method of claim 1, wherein the secondary cross-linking is carried out after the main cross-linking or the main cross-linking is carried out after the secondary cross-linking. 7. According to the method of claim 1, the main cross-linking, secondary cross-linking, or a combination of primary and secondary cross-linking processes is repeated at least twice. A polarizing plate is formed by laminating a protective film on at least one side of a polarizer produced by the manufacturing method according to any one of claims 1 to 7. 9. The polarizing plate of claim 8, further comprising at least one selected from the group consisting of a phase retardation film laminated on a polarizer or a polarizer protective film, a viewing angle compensation film, and a brightness enhancement film. 10. An image display device comprising a polarizing plate according to item 8 of the patent application. 24 201144362 IV. Designation of representative drawings: (1) The representative representative of the case is: ( ). (2) A brief description of the symbol of the representative figure: None 5. If there is a chemical formula in this case, please disclose the chemical formula that best shows the characteristics of the invention: Benefit * »»> 2