JP7046901B2 - Polarizer and its manufacturing method - Google Patents

Description

The present invention relates to a substituent and a method for manufacturing the same. More specifically, the present invention relates to a polarizing element having excellent quality even when cut, and a method for producing the same.

The polarizing plate is used in various image display devices such as mobile phones and notebook personal computers (PCs). In recent years, the demand for polarizing plates has been increasing for various applications such as smartphones and in-vehicle displays. In these applications, the polarizing plate may be modified to correspond to the mounted portion and may be processed to provide an opening. For example, Patent Document 1 proposes a polarizing plate having an opening in a portion corresponding to a camera. However, when these processings are performed, there is a problem that cracks are generated in the polarizing element during processing and the quality of the polarizing element is deteriorated.

Japanese Unexamined Patent Publication No. 2014-11238

The present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a polarizing element having excellent quality even when a cutting process is performed.

The polarizing element of the present invention has a dyed portion, a cut-processed portion, and a decolorized portion formed between the dyed portion and the cut-processed portion.
In one embodiment, the distance from the cutting portion to the dyeing portion is 0.1 mm or more.
In one embodiment, the cutting section is a laser cutting section.
In one embodiment, the alkali metal and / or alkaline earth metal content of the decolorized portion is 3.6% by weight or less.
In one embodiment, the boric acid content of the decolorized portion is 8% by weight or less.
In one embodiment, the shortest distance between the decolorized portion and the end portion of the polarizing element is 15 mm or less.
In one embodiment, the difference between the content of the dichroic substance in the dyed portion and the content of the dichroic substance in the decolorized portion is 0.5% by weight or more.
In another aspect of the present invention, there is provided a method for manufacturing a polarizing element. The production method of the present invention includes imparting a polarizing function to the resin film, decolorizing the resin film to which the polarizing function is imparted, and cutting a part of the decolorized portion.
In one embodiment, the cutting process is performed by a laser.
In one embodiment, the decolorization is performed by contacting with a basic solution.

According to the present invention, a polarizing element having excellent quality (for example, crack resistance) is provided even when a cutting process is performed. The polarizing element of the present invention has a dyed portion, a cut-processed portion, and a decolorizing portion formed between the dyed portion and the cut-processed portion. Since the decolorized portion is formed between the cut portion and the dyed portion, even when cutting processing such as deformation processing and formation of an opening is performed, the inside of the stator (more than) from the cutting processing portion. Specifically, it is possible to prevent the occurrence of cracks in the dyed portion). Further, it is possible to satisfactorily prevent the color loss of the polarizing element due to the intrusion of water into the dyed portion from the generated cracks.

Further, the method for producing a polarizing element of the present invention comprises imparting a polarizing function to a resin film, decolorizing the resin film to which the polarizing function is imparted, and cutting the decolorized portion. include. In the manufacturing method of the present invention, a part of the decolorized portion of the resin film to which the polarizing function is imparted is cut. By cutting the decolorized portion of the resin film so as to leave a desired decolorized portion, it is possible to better prevent the generation of cracks due to the stress applied during the cutting process. Further, the frequency of crack generation can be suppressed, and the productivity of a high-quality polarizing element can be improved.

FIG. 3 is a schematic plan view of a polarizing element according to one embodiment of the present invention. It is a schematic plan view of the resin film subjected to the cutting process in one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Polarizer The polarizing element of the present invention has a dyed portion, a cut-processed portion, and a decolorizing portion formed between the dyed portion and the cut-processed portion. The splitter is typically imparted with a polarizing function by dyeing a resin film with a dichroic substance. That is, in the polarizing element, the portion that exerts its function is a dyed portion dyed with a dichroic substance. Depending on the application, the polarizing element may be subjected to cutting processing such as deformation processing and formation of an opening. When the cutting process is performed, cracks may occur from the cutting process portion, and the quality of the polarizing element may deteriorate. Further, the moisture invading from the crack may cause the dyed portion to lose color, and the polarizing function of the stator may be impaired. In the polarizing element of the present invention, a decolorized portion is formed between the dyed portion and the cut-processed portion. As a result, the generation of cracks from the cut portion of the polarizing element can be prevented. Further, even when cracks occur, it is possible to prevent the cracks from entering the dyed portion and maintain a good polarization function.

FIG. 1 is a schematic plan view of a polarizing element according to one embodiment of the present invention. In the polarizing element 10 of the illustrated example, a cutting processing portion 11 is formed inside the dyeing portion 12. In the illustrated example, the cutting portion 11 is an opening. A decolorizing portion 13 is formed between the dyeing portion 12 and the cutting processing portion 11. Since the decolorized portion 13 is formed, it is possible to prevent the generation of cracks from the cut portion of the cut portion 11. Further, even when cracks occur, it is possible to prevent the cracks generated in the cutting portion 11 from stopping at the decolorizing portion 13 and reaching the dyeing portion 12. Further, it is possible to prevent color loss of the dyed portion 12 due to moisture invading from the generated cracks. In the illustrated example, the decolorized portion 13 is formed on the entire peripheral portion of the cut portion 11, but it is sufficient that the decolorized portion is formed at least partially.

In another embodiment, a plurality of cutting processed portions (for example, two or more openings) may be formed in the dyeing portion 12. Even when there are two or more cut parts as in this embodiment, by forming a decolorized part between the dyed part and the cut part, the generation of cracks from each cut part is good. Can be prevented. Further, even when cracks occur, it is possible to prevent the cracks from entering the dyed portion and maintain a good polarization function.

The splitter 10 can be designed into any suitable shape depending on the intended use and the like. Examples of the shape of the splitter 10 include a rectangle, a circle, a rhombus, and an irregular shape. As described above, the stator of the present invention can satisfactorily prevent the generation of cracks from the cut portion. Further, even when cracks occur, it is possible to prevent the cracks from entering the dyed portion and maintain a good polarization function. Therefore, even when the polarizing element 10 is a deformed polarizing element, it is possible to provide a polarizing element having excellent quality.

The cut portion is formed by cutting the resin film by any suitable cutting method. Examples of the cutting method include a laser, a cutter, a punching blade such as a Thomson blade and a pinnacle blade, and the like. The cutting portion is preferably a laser cutting portion. Since the portion is cut by the laser, minute cracks at the cut end portion can be reduced, and the crack resistance after the reliability test can be improved as compared with other cutting methods.

The thickness of the stator can be set to any suitable value. The thickness is typically 0.5 μm or more and 80 μm or less, preferably 30 μm or less, more preferably 25 μm or less, still more preferably 18 μm or less, particularly preferably 12 μm or less, still more preferably. Is less than 8 μm. The lower limit of the thickness is preferably 1 μm or more. The thin thickness can contribute to the thinning of the image display device. Further, the thinner the thickness, the better the decolorized portion can be formed. Specifically, when the basic solution described later is brought into contact with each other, the decolorized portion can be formed in a shorter time. In addition, the thickness of the portion in contact with the basic solution may be thinner than that of the other portions. Since the thickness is thin, the difference in thickness between the portion in contact with the basic solution and the other portion can be reduced. Further, when the color is decolorized by a laser, the absorbance per unit film thickness becomes high, and the color can be decolorized efficiently.

As described above, the polarizing element is typically obtained by dyeing a resin film with a dichroic substance such as iodine. Any suitable resin can be used as the resin for forming the resin film. Preferably, a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") is used. Examples of the PVA-based resin include polyvinyl alcohol and an ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. Is. The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizing element having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.

The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the intended purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. Iodine is preferably used. This is because the decolorized portion can be satisfactorily formed by contact with a basic solution described later.

The modulator (stained portion) preferably exhibits absorption dichroism in the wavelength range of 380 nm to 780 nm. The simple substance transmittance (Ts) of the splitter (stained portion) is preferably 39% or more, more preferably 39.5% or more, still more preferably 40% or more, and particularly preferably 40.5% or more. The theoretical upper limit of the single transmittance is 50%, and the practical upper limit is 46%. The single transmittance (Ts) is a Y value measured by a double field of view (C light source) of JIS Z 8701 and corrected for luminosity factor. For example, a microspectroscopy system (manufactured by Lambdavision, LVmicro) is used. Can be measured. The degree of polarization of the polarizing element (stained portion) is preferably 99.8% or more, more preferably 99.9% or more, still more preferably 99.95% or more.

The width of the decolorized portion (specifically, the distance from the cut portion to the dyed portion, the double arrow in FIG. 1) is preferably 0.1 mm or more, more preferably 0.5 mm or more, still more preferably. It is 1.0 mm or more. When the width of the decolorized portion is within such a range, the occurrence of cracks from the cut portion can be satisfactorily prevented. Further, even when cracks occur, it is possible to prevent the cracks from reaching the dyed portion. Further, it is possible to prevent the moisture from reaching the dyed portion even when the moisture invades from the generated crack. The width of the decolorized portion is, for example, 10 mm or less, preferably 5 mm or less, from the viewpoint of securing the dyed portion. The width of the decolorized portion may include a portion of at least 0.1 mm or more.

The shortest distance between the decolorized portion and the end portion of the polarizing element (for example, the dashed double arrow in FIG. 1) is preferably 15 mm or less, more preferably 10 mm or less, and further preferably 5 mm or less. When the distance between the decolorized portion and the end portion of the polarizing element is within the above range, the stress due to the cutting process can be relaxed, and the generation of cracks can be suppressed. The distance between the decolorized portion and the end portion of the polarizing element is, for example, 0.1 mm or more.

The transmittance of the decolorized portion (for example, the transmittance measured with light having a wavelength of 550 nm at 23 ° C.) is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90% or more. be.

As described in Section B, the bleached portion can be formed by any suitable method. When the decolorized portion is formed by contact with a basic solution, the content of the dichroic substance in the decolorized portion is preferably 1.0% by weight or less, more preferably 0.5% by weight or less, still more preferably 0. .2% by weight or less. When the content of the dichroic substance in the decolorized portion is within such a range, the generation of cracks from the cut portion can be prevented more satisfactorily. On the other hand, the lower limit of the content of the dichroic substance in the decolorized portion is usually not more than the detection limit. When iodine is used as the bicolor substance, the iodine content can be determined, for example, from the X-ray intensity measured by fluorescent X-ray analysis by a calibration curve prepared in advance using a standard sample.

The difference between the content of the dichroic substance in the dyed portion and the content of the dichroic substance in the decolorized portion is preferably 0.5% by weight or more, more preferably 1% by weight or more. When the difference in content is within such a range, the occurrence of cracks from the cut portion can be prevented more satisfactorily. Furthermore, it is possible to form a decolorized portion having desired transparency.

The polarizing element may contain boric acid depending on the manufacturing process thereof (for example, the cross-linking step described later). The boric acid content of the decolorized portion is, for example, 8% by weight or less, preferably 5% by weight or less. The boric acid content of the decolorized portion is, for example, 0% by weight or more. When the boric acid content of the decolorized portion is within the above range, the occurrence of cracks from the cut portion can be satisfactorily prevented.

The decolorized portion has an alkali metal and / or alkaline earth metal content of preferably 3.6% by weight or less, more preferably 2.5% by weight or less, still more preferably 1.0% by weight or less. It is particularly preferably 0.5% by weight or less. When the content of the alkali metal and / or the alkaline earth metal in the decolorized portion is within such a range, the shape of the decolorized portion formed by contact with the basic solution described later can be well maintained (that is,). , It can prevent the decolorized part from expanding to an undesired part). The content can be determined, for example, from the X-ray intensity measured by fluorescent X-ray analysis by a calibration curve prepared in advance using a standard sample. Such a content can be realized by reducing the alkali metal and / or the alkaline earth metal at the contact portion in contact with the basic solution described later.

B. Method for Producing a Polarizer The splitter of the present invention can be manufactured by any suitable method. In one embodiment, the method for producing a polarizing element of the present invention comprises imparting a polarizing function to a resin film (forming a dyed portion), bleaching the resin film to which the polarizing function is imparted, and decolorizing the resin film. It includes cutting a part of the decolorized portion.

B-1. Addition of polarization function The polarization function can be imparted to the resin film by any suitable method. Typically, the resin film can be imparted with a polarizing function by subjecting the resin film to various treatments such as swelling treatment, stretching treatment, dyeing treatment with a dichroic substance such as iodine, cross-linking treatment, cleaning treatment, and drying treatment. When the resin film is subjected to the treatment of imparting the polarizing function, the resin film may be a resin layer formed on the base material. The laminate of the base material and the resin layer can be obtained, for example, by a method of applying a coating liquid containing the material for forming the resin film to the base material, a method of laminating a resin film on the base material, or the like.

In the stretching treatment, the resin film is typically uniaxially stretched 3 to 7 times. The stretching direction may correspond to the absorption axis direction of the obtained polarizing element.

The dyeing treatment is typically performed by adsorbing a dichroic substance. Examples of the adsorption method include a method of immersing a resin film in a dyeing solution containing a dichroic substance, a method of applying the dyeing solution to the resin film, a method of spraying the dyeing solution onto the resin film, and the like. .. A method of immersing the resin film in the dyeing solution is preferable. This is because the dichroic substance can be adsorbed well. The dichroic substance is as described above.

When iodine is used as the dichroic substance, an aqueous iodine solution is preferably used as the dyeing solution. The blending amount of iodine is preferably 0.04 part by weight to 5.0 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add iodide to the aqueous iodine solution. Potassium iodide is preferably used as the iodide. The blending amount of iodide is preferably 0.3 parts by weight to 15 parts by weight with respect to 100 parts by weight of water.

B-2. Decolorization Next, the resin film imparted with the polarizing function is decolorized. Decolorization can be performed by any suitable method. For example, decolorization treatment by laser, decolorization treatment by contact with a basic solution containing a basic compound, and the like can be mentioned. Contact with a basic solution is preferred. By decolorizing by contact with the basic solution, the boric acid content of the portion in contact with the basic solution can also be reduced, and the strength of the resin film (decolorized portion) at the time of cutting can be improved. .. In addition, the transparency of the decolorized portion over time can be maintained.

Any suitable method can be adopted as the contact method for the basic solution. For example, a method of dropping, coating, and spraying a basic solution on a resin film, and a method of immersing a resin film in a basic solution can be mentioned.

When contacting the basic solution, the stator (resin film) may be protected with any suitable protective material so that the basic solution does not come into contact with any part other than the desired site (to prevent decolorization). Specifically, the protective material includes a surface protective film. The surface protective film is temporarily used during the manufacture of the stator. Since the surface protective film is removed from the resin film at an arbitrary appropriate timing, it is typically attached to the resin film via an adhesive layer. Another specific example of the surface protective material is a photoresist or the like.

As the basic compound, any suitable basic compound can be used. Examples of the basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, and inorganic alkali metal salts such as sodium carbonate. , Organic alkali metal salts such as sodium acetate, aqueous ammonia and the like. Among these, hydroxides of alkali metals and / or alkaline earth metals are preferably used, and sodium hydroxide, potassium hydroxide and lithium hydroxide are more preferably used. The dichroic substance can be efficiently ionized, and the decolorized portion can be formed more easily. These basic compounds may be used alone or in combination of two or more.

As the solvent of the basic solution, any suitable solvent can be used. Specific examples thereof include water, alcohols such as ethanol and methanol, ether, benzene, chloroform, and a mixed solvent thereof. Among these, water and alcohol are preferably used because the ionized dichroic substance can be satisfactorily transferred to the solvent.

The concentration of the basic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N. When the concentration is in such a range, the desired decolorized portion can be well formed.

The liquid temperature of the basic solution is, for example, 20 ° C to 50 ° C. The contact time between the resin film and the basic solution can be set according to the thickness of the resin film, the type of the basic compound, and the concentration of the basic solution, and is, for example, 5 seconds to 30 minutes.

B-3. Cutting of the resin film Next, a part of the decolorized portion of the resin film (hereinafter, also referred to as an intermediate decolorized portion) is cut. More specifically, the cutting process is performed by cutting the intermediate decolorized portion of the resin film so that the desired decolorized portion remains. By performing the cutting process so that the decolorized portion remains, the crack invades the dyed portion even when a crack occurs, and in one embodiment, the decolorization is performed by contact with a basic solution. The boric acid content in the resin film (polarizer) can be reduced by performing the decolorization treatment by contact with the basic solution. By reducing the boric acid content of the resin film, the stress of the resin film on the cutting process can be further suppressed. By cutting the portion where the boric acid content is reduced (intermediate decolorization portion), the generation of cracks from the cut portion can be prevented. In addition, the productivity of high quality (for example, cracked) polarizing elements can be improved. Preferably, the cutting process is performed so that the entire cutting processing portion fits within the decolorized portion.

FIG. 2 is a schematic plan view of a resin film used in the cutting process in one embodiment of the present invention. In the illustrated example, the resin film 20 has an intermediate bleaching portion 14 on the peripheral edge portion. The resin film 20 is cut at the intermediate decolorizing portion 14 (broken line portion in the illustrated example). As a result, a splitter having a decolorized portion on the entire peripheral edge of the dyed portion can be obtained, in which the outer edge of the polarizing element is the cut portion.

Examples of the cutting method include a laser, a cutter, a punching blade such as a Thomson blade and a picnal blade, and the like. Preferably, the cutting process is performed by a laser. By using a laser, minute cracks at the cut end can be reduced, and crack resistance after a reliability test can be improved as compared with other cutting methods.

As the laser, any suitable laser can be used. For example, a gas laser such as a CO ₂ laser; a solid state laser such as a YAG laser; a semiconductor laser can be mentioned. Preferably, a CO ₂ laser is used. The irradiation conditions of the laser light can be set to any suitable conditions depending on, for example, the laser used. The output conditions are preferably 20 W to 60 W, more preferably 35 W to 45 W.

B-4. Reduction of Alkali Metals and / or Alkaline Earth Metals As described above, it is preferable to decolorize the resin film by contact with a basic solution. When decolorization is performed by contacting with a basic solution, hydroxides of alkali metal and / or alkaline earth metal may remain in the contact portion. Further, by contacting the resin film with the basic solution, a metal salt of an alkali metal and / or an alkaline earth metal can be formed at the contact portion. These can generate hydroxide ions, and the generated hydroxide ions can act (decompose / reduce) on a dichroic substance (for example, an iodine complex) existing around the contact portion to widen the decolorized region. .. Therefore, it is preferable to reduce the alkali metal and / or alkaline earth metal contained in the resin film at the contact portion where the basic solution is brought into contact after the contact with the basic solution. By reducing the amount of alkali metal and / or alkaline earth metal, a decolorized portion having excellent dimensional stability can be obtained.

As the reduction method, a method of bringing the treatment liquid into contact with the contact portion with the basic solution is preferably used. According to such a method, the alkali metal and / or the alkaline earth metal can be transferred from the resin film to the treatment liquid, and the content thereof can be reduced.

Any suitable method can be adopted as the contact method of the treatment liquid. For example, a method of dropping, coating, and spraying the treatment liquid on the contact portion with the basic solution, and a method of immersing the contact portion with the basic solution in the treatment liquid can be mentioned.

When the resin film is protected with an arbitrary suitable protective material at the time of contact with the basic solution, it is preferable to contact the treatment liquid as it is (particularly when the temperature of the treatment liquid is 50 ° C. or higher). According to such a form, it is possible to prevent deterioration of the polarization characteristics due to the treatment liquid at a portion other than the contact portion with the basic solution.

The treatment liquid may contain any suitable solvent. Examples of the solvent include water, alcohols such as ethanol and methanol, ether, benzene, chloroform, and a mixed solvent thereof. Among these, water and alcohol are preferably used from the viewpoint of efficiently transferring alkali metals and / or alkaline earth metals. As the water, any suitable water can be used. For example, tap water, pure water, deionized water and the like can be mentioned.

The temperature of the treatment liquid at the time of contact is, for example, 20 ° C. or higher, preferably 50 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher. At such temperatures, alkali metals and / or alkaline earth metals can be efficiently transferred to the treatment liquid. Specifically, the swelling rate of the resin film can be significantly improved, and the alkali metal and / or the alkaline earth metal in the resin film can be physically removed. On the other hand, the temperature of water is substantially 95 ° C. or lower.

The contact time can be appropriately adjusted according to the contact method, the temperature of the treatment liquid (water), the thickness of the resin film, and the like. For example, when immersed in warm water, the contact time is preferably 10 seconds to 30 minutes, more preferably 30 seconds to 15 minutes, and even more preferably 60 seconds to 10 minutes.

In one embodiment, an acidic solution is used as the treatment solution. By using an acidic solution, the alkali metal and / or alkaline earth metal hydroxide remaining on the resin film is neutralized, and the alkali metal and / or alkaline earth metal in the resin film is chemically removed. be able to.

As the acidic compound contained in the acidic solution, any suitable acidic compound can be used. Examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride and boric acid, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid and benzoic acid. The acidic compound contained in the acidic solution is preferably an inorganic acid, more preferably hydrochloric acid, sulfuric acid or nitric acid. These acidic compounds may be used alone or in combination of two or more.

Preferably, as the acidic compound, an acidic compound having a higher acidity than boric acid is preferably used. This is because it can also act on metal salts (borates) of alkali metals and / or alkaline earth metals. Specifically, boric acid can be liberated from borate to chemically remove alkali metals and / or alkaline earth metals in the resin film.

Examples of the index of acidity include an acid dissociation constant (pKa), and an acidic compound having a pKa smaller than that of boric acid pKa (9.2) is preferably used. Specifically, pKa is preferably less than 9.2, more preferably 5 or less. pKa may be measured using any suitable measuring device, or may refer to the values described in documents such as the Chemical Society of Japan, Revised 5th Edition (edited by the Chemical Society of Japan, Maruzen Publishing). Further, in the case of an acidic compound that dissociates in multiple stages, the value of pKa may change at each stage. When such an acidic compound is used, one in which any of the pKa values at each stage is within the above range is used. In the present specification, pKa refers to a value in an aqueous solution at 25 ° C.

The difference between the pKa of the acidic compound and the pKa of boric acid is, for example, 2.0 or more, preferably 2.5 to 15, and more preferably 2.5 to 13. Within such a range, the alkali metal and / or alkaline earth metal can be efficiently transferred to the treatment liquid, and as a result, the desired alkali metal and / or alkaline earth metal content in the decolorized portion can be obtained. It can be realized.

Examples of the acidic compound that can satisfy the above pKa include hydrochloric acid (pKa: -3.7), sulfuric acid (pK ₂ : 1.96), nitric acid (pKa: -1.8), and hydrogen fluoride (pKa: 3). .17), inorganic acids such as boric acid (pKa: 9.2), formic acid (pKa: 3.54), oxalic acid (pK ₁ : 1.04, pK ₂ : 3.82), citric acid (pK ₁ ). : 3.09, pK ₂ : 4.75, pK ₃ : 6.41), acetic acid (pKa: 4.8), benzoic acid (pKa: 4.0) and other organic acids and the like can be mentioned.

The solvent of the acidic solution (treatment liquid) is as described above, and even in this embodiment in which the acidic solution is used as the treatment liquid, the alkali metal and / or the alkaline earth metal in the resin film is physically removed. obtain.

The concentration of the acidic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N.

The liquid temperature of the acidic solution is, for example, 20 ° C to 50 ° C. The contact time with the acidic solution can be set according to the thickness of the resin film, the type of the acidic compound, and the concentration of the acidic solution, and is, for example, 5 seconds to 30 minutes.

B-5. Other Steps The method for producing a polarizing element of the present invention includes imparting a polarizing function to a resin film, decolorizing a resin film to which a polarizing function has been imparted, cutting and processing a decolorized portion, and any method. In addition to reducing the content of alkali metals and / or alkaline earth metals, any other suitable treatment step may be further included. Other treatment steps include removal of basic and / or acidic solutions, cleaning and the like.

Specific examples of the method for removing the basic solution and / or the acidic solution include wiping removal with a waste cloth, suction removal, natural drying, heat drying, blast drying, vacuum drying and the like. The drying temperature is, for example, 20 ° C to 100 ° C.

The cleaning process is carried out by any suitable method. Examples of the solution used for the cleaning treatment include pure water, alcohols such as methanol and ethanol, acidic aqueous solutions, and mixed solvents thereof. The cleaning process can be performed at any suitable stage. The cleaning treatment may be performed a plurality of times.

C. Polarizing plate The polarizing plate of the present invention has the above-mentioned polarizing element. The polarizing plate of the present invention is typically used by laminating a protective film on at least one side thereof. Examples of the material for forming the protective film include cellulose resins such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic resins, cycloolefin resins, olefin resins such as polypropylene, and ester resins such as polyethylene terephthalate resins. , Polyamitone-based resin, polycarbonate-based resin, co-heavy resin thereof and the like.

A hard coat layer, an antireflection treatment layer, and a treatment layer for diffusion or antiglare may be formed as a surface treatment layer on the surface of the protective film on which the stator is not laminated.

The thickness of the protective film is preferably 10 μm to 100 μm. The protective film is typically laminated on a polarizing element via an adhesive layer (specifically, an adhesive layer and an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive or an activation energy ray-curable adhesive. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive.

D. Image display device The image display device of the present invention includes the above-mentioned polarizing plate. Examples of the image display device include a liquid crystal display device and an organic EL device. Specifically, the liquid crystal display device includes a liquid crystal panel including a liquid crystal cell and the above-mentioned polarizing elements arranged on one side or both sides of the liquid crystal cell. The organic EL device includes an organic EL panel in which the above-mentioned polarizing element is arranged on the visual recognition side. As described above, the splitter of the present invention prevents the occurrence of cracks even when it has a cut portion, and as a result, prevents the splitter from losing color and impairing the polarization characteristics. obtain. Since the cut portion has excellent quality even if it is formed, the desired polarization characteristics can be maintained even when the cut portion is processed into a more complicated shape such as a deformed portion or an opening.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
As a base material, an amorphous isophthalic acid copolymer polyethylene terephthalate (IPA copolymer PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. was used. One side of the substrate is corona-treated, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6) are applied to the corona-treated surface. %, Degree of polymerization of 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z200") is applied at a ratio of 9: 1 and dried at 25 ° C. to a thickness of 11 μm. A PVA-based resin layer was formed to prepare a laminated body.
The obtained laminate was uniaxially stretched at the free end in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (aerial auxiliary stretching).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was mixed with 100 parts by weight of water, and 1.5 parts by weight of potassium iodide was mixed and immersed in the obtained iodine aqueous solution for 60 seconds (dyeing treatment). ..
Then, it was immersed in a cross-linked bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70 ° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). However, uniaxial stretching was performed between rolls having different peripheral speeds so that the total stretching ratio was 5.5 times in the longitudinal direction (longitudinal direction) (underwater stretching).
Then, the laminate was immersed in a washing bath having a liquid temperature of 30 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Subsequently, a PVA-based resin aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer (registered trademark) Z-200", resin concentration: 3% by weight) is applied to the surface of the PVA-based resin layer of the laminate. A protective film (thickness 25 μm) was attached and heated in an oven maintained at 60 ° C. for 5 minutes. Then, the substrate was peeled off from the PVA-based resin layer to obtain a polarizing plate (polarizer (transmittance 42.3%, thickness 5 μm) / protective film).

A 200 mm × 300 mm test piece was cut out from the polarizing plate having a total thickness of 30 μm obtained above. A basic solution at room temperature (sodium hydroxide aqueous solution, 1.0 mol / L (1N)) was applied to the central portion of the polarizing plate of the cut polarizing plate so as to form a circle with a diameter of 2.8 mm, and the mixture was left for 60 seconds. Then, the applied sodium hydroxide aqueous solution was removed with a waste cloth. After removing the aqueous sodium hydroxide solution, 1.0 mol / L (1N) hydrochloric acid was applied to the portion contacted with the basic solution and left for 30 seconds. Next, hydrochloric acid was removed with a waste cloth to obtain a polarizing element having a transparent portion (intermediate bleaching portion) formed. The sodium content of the transparent portion was 3.6% by weight or less, and the boric acid content was 8% by weight or less.

Cut a 0.8 mm circle with a laser (CO ₂ laser, irradiation conditions: speed 650 mm / sec, frequency 30 kHz, output 40 W) so that the width of the decolorized portion remaining after cutting from the center of the formed intermediate decolorized portion is 1 mm. A polarizing element having a decolorized portion having a width of 1 mm was obtained.

[Example 2]
A polarizing element having a decolorized portion having a width of 0.5 mm was obtained in the same manner as in Example 1 except that the decolorized portion remaining after cutting was cut so as to have a width of 0.5 mm.

[Example 3]
A polarizing element having a decolorized portion having a width of 1 mm was obtained in the same manner as in Example 1 except that a transparent portion (diameter 2.8 mm) was formed in a portion 1 mm from the long side of the cut out test piece.

[Example 4]
A substituent having a transparent portion (intermediate decolorization portion) was obtained in the same manner as in Example 1 except that the basic solution was applied so as to form a circle with a diameter of 20 mm.
A circle of 18 mm was cut in the same manner as in Example 1 so that the width of the decolorized portion remaining after cutting from the center of the transparent portion of the polarizing element was 1 mm, and a polarizing element having a decolorized portion having a width of 1 mm was obtained.

[Example 5]
A polarizing element having a decolorized portion having a width of 1 mm was obtained in the same manner as in Example 4 except that a transparent portion was formed in a portion 1 mm from the long side of the cut out test piece.

[Example 6]
A transparent laser (solid (YAG) laser, irradiation conditions: speed 100 mm / sec, frequency 3120 kHz, pulse energy: 40 μJ) was used at the center of the polarizing element of the test piece obtained in Example 1 to have a diameter of 2.8 mm. Formed a part.
Laser (CO ₂ laser, irradiation condition: speed 650 mm / sec, frequency 30 kHz, output 40 W) so that the width of the decolorized part remaining after cutting from the center of this transparent part (intermediate decolorized part) is 1 mm. To obtain a polarizing element having a decolorized portion having a width of 1 mm.

[Example 7]
A polarizing element having a decolorized portion having a width of 0.5 mm was obtained in the same manner as in Example 6 except that the decolorized portion remaining after cutting was cut so as to have a width of 0.5 mm.

(Comparative Example 1)
A substituent was obtained in the same manner as in Example 1 except that a transparent portion (intermediate decolorization portion) was not formed on the test piece and an opening having a diameter of 2.8 mm was formed by a laser.

(Comparative Example 2)
A substituent was obtained in the same manner as in Example 3 except that a transparent portion (intermediate decolorization portion) was not formed on the test piece and an opening having a diameter of 2.8 mm was formed by a laser.

(Comparative Example 3)
A substituent was obtained in the same manner as in Example 1 except that a transparent portion (intermediate decolorization portion) was not formed on the test piece and an opening having a diameter of 20 mm was formed by a laser.

The following evaluations were performed using the substituents obtained in Examples 1 to 7 and Comparative Examples 1 to 3. The results are shown in Table 1.

(Maximum crack length after heat cycle test (H / S test))
A glass having a thickness of 1 mm was bonded to the obtained polarizing element via an adhesive layer having a thickness of 23 μm to obtain a laminated body. The obtained laminate was left in an atmosphere of −40 ° C. for 30 minutes and then left in an atmosphere of 85 ° C. for 30 minutes. This operation was defined as one cycle. The laminate was taken out at the stages of 20 cycles, 50 cycles, 100 cycles, and 200 cycles, and the presence or absence of cracks was observed with an optical microscope, and if cracks were generated, the maximum length thereof was measured. If the maximum crack length after 200 cycles is 1 mm or less, the crack resistance is excellent.

(Light loss)
The presence or absence of color loss in the dyed portion of the laminated body obtained by performing the above heat cycle test for 200 cycles was confirmed with an optical microscope.

(Number of cracks)
The presence or absence of cracks in the laminated body obtained by performing the above heat cycle test for 300 cycles was confirmed with an optical microscope. The three laminated bodies were evaluated, and the average value was taken as the number of cracks.

(Difference in iodine content between dyed and decolorized areas)
From the X-ray intensity measured by fluorescent X-ray analysis of the iodine content of the decolorized part and the dyed part of the polarizing element of each example and comparative example under the following conditions, the iodine content was determined by a calibration curve prepared in advance using a standard sample. I asked. From the obtained iodine content value, the difference in iodine content between the decolorized part and the dyed part was calculated.

Dichroic substance low concentration part ・ Analytical device: Fluorescent X-ray analyzer (XRF) manufactured by Rigaku Denki Kogyo Product name "ZSX100e"
・ Anti-cathode: Rhodium ・ Spectral crystal: Lithium fluoride ・ Excitation light energy: 40kV-90mA
-Iodine measurement line: I-LA
・ Quantitative method: FP method ・ 2θ angle peak: 103.078deg (iodine)
・ Measurement time: 40 seconds

In the substituents of Examples 1 to 7 having a decolorized portion between the cut portion and the dyed portion, only extremely small cracks were confirmed even after the heat shock test of 200 cycles. Further, in the substituents of Examples 1 to 7, the number of cracks was small even in the substituents after the heat shock test of 300 cycles, and the substituents having excellent crack resistance could be stably obtained. In the substituents of Comparative Examples 1 to 3 in which the openings were formed without the decolorization treatment (without the decolorization portion), cracks larger than those in the examples were confirmed after the heat shock test of 200 cycles. In addition, the number of cracks generated was large and there was room for improvement in productivity.

The splitter of the present invention is suitably used for an image display device such as a liquid crystal display device and an organic EL device.

10 Polarizer 11 Cutting part 12 Dyeing part 13 Decolorizing part 14 Intermediate decolorizing part 20 Resin film

Claims (7)

It has a dyed portion, an opening formed in the dyed portion, and a decolorized portion formed between the dyed portion and the opening .
The alkali metal and / or alkaline earth metal content of the decolorized portion is 3.6% by weight or less, and the boric acid content is 8% by weight or less.
Polarizer. The polarizing element according to claim 1, wherein the decolorized portion has a width of 0.1 mm or more. The polarizing element according to claim 1 or 2, wherein the opening is a laser cutting portion. The polarizing element according to any one of claims 1 to 3, wherein the shortest distance between the decolorized portion and the end portion of the polarizing element is 15 mm or less. The polarizing element according to any one of claims 1 to 4, wherein the difference between the content of the dichroic substance in the dyed portion and the content of the dichroic substance in the decolorized portion is 0.5% by weight or more. Adding a polarizing function to the resin film and
Decolorizing the resin film imparted with the polarizing function and
Including forming an opening in a part of the decolorized portion,
The decolorization is performed by contacting the resin film with a basic solution.
Further comprising treating the decolorized portion with hydrochloric acid, sulfuric acid or nitric acid to reduce alkali metals and / or alkaline earth metals prior to forming the openings .
How to manufacture a extruder. The method for manufacturing a polarizing element according to claim 6, wherein the opening is formed by a laser.

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