WO2023037939A1 - 偏光フィルム及び偏光板の製造方法 - Google Patents

偏光フィルム及び偏光板の製造方法 Download PDF

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Publication number
WO2023037939A1
WO2023037939A1 PCT/JP2022/032727 JP2022032727W WO2023037939A1 WO 2023037939 A1 WO2023037939 A1 WO 2023037939A1 JP 2022032727 W JP2022032727 W JP 2022032727W WO 2023037939 A1 WO2023037939 A1 WO 2023037939A1
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Prior art keywords
film
treatment
bath
polarizing film
polarizing
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PCT/JP2022/032727
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English (en)
French (fr)
Japanese (ja)
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邦智 齋藤
成志 中里
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住友化学株式会社
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/02—Chemical treatment or coating of shaped articles made of macromolecular substances with solvents, e.g. swelling agents
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to a method for manufacturing a polarizing film and a polarizing plate.
  • image display devices containing polarizing plates have been used in mobile devices such as mobile phones and tablet terminals, as well as in-vehicle image display devices such as car navigation devices and back monitors.
  • image display devices are required to have higher durability in harsher environments (for example, in high-temperature environments) than has been conventionally required.
  • Patent Document 1 discloses that the pH of the polarizer is lowered to provide a polarizing plate with excellent optical properties and wet heat durability. Patent Document 1 describes a method for lowering the pH of the polarizer by adjusting the pH of the hardener to 1.5 to 3.2.
  • the interlayer filling structure means that a polarizing plate arranged on the viewer side surface of the image display panel and a transparent member such as glass further arranged on the viewer side are adhered with an adhesive or a UV curable adhesive. (see, for example, Patent Document 2).
  • the polarizing film when optimizing a polarizing film to suppress the polyene conversion of polyvinyl alcohol that occurs when an interlayer-filling structure is used, the polarizing film suffers from a decrease in single transmittance when the interlayer-filling structure is not used. It was necessary to prepare the optimum polarizing film individually for the configuration used.
  • the object of the present invention is that when exposed to a high temperature environment exceeding 95 ° C., the effect of suppressing yellowing is excellent when the interlayer filling structure is used, and the single transmittance is improved when the interlayer filling structure is not used.
  • An object of the present invention is to provide a method for producing a polarizing film capable of suppressing deterioration.
  • Another object of the present invention is to provide a method for producing a polarizing plate comprising the polarizing film.
  • the present invention provides a method for producing a polarizing film and a method for producing a polarizing plate, which are described below.
  • a method for producing a polarizing film from a polyvinyl alcohol resin film comprising: A treatment step of bringing the polyvinyl alcohol resin film into contact with a treatment liquid, The method for producing a polarizing film, wherein the treatment liquid contains nitrate, boric acid and zinc iodide, and has a pH of 4.3 or more at 25°C.
  • the method for producing a polarizing film according to [1] wherein the treatment liquid has a pH of 6.5 or less at 25°C.
  • the effect of suppressing yellowing is excellent when the interlayer filling structure is used, and the single transmittance is excellent when the interlayer filling structure is not used.
  • a method for producing a polarizing film and a method for producing a polarizing plate having the polarizing film can be provided, which can suppress the deterioration.
  • the polarizing film is a uniaxially stretched polyvinyl alcohol resin film in which a dichroic dye (iodine or dichroic dye) is adsorbed and oriented.
  • the polyvinyl alcohol-based resin that constitutes the polyvinyl alcohol-based resin film is usually obtained by saponifying a polyvinyl acetate-based resin.
  • the degree of saponification is generally about 85 mol% or more, preferably about 90 mol% or more, more preferably about 99 mol% or more.
  • the polyvinyl acetate-based resin may be, for example, polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other monomers copolymerizable therewith.
  • examples of other copolymerizable monomers include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like.
  • the degree of polymerization of the polyvinyl alcohol resin is generally about 1000-10000, preferably about 1500-5000.
  • polyvinyl alcohol-based resins may be modified, for example, aldehyde-modified polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. may be used.
  • a polyvinyl alcohol-based resin film having a thickness of usually 65 ⁇ m or less (for example, 60 ⁇ m or less), preferably 50 ⁇ m or less, more preferably 35 ⁇ m or less, and even more preferably 30 ⁇ m or less is used as a material for starting the production of the polarizing film. (Original film) is used. This makes it possible to obtain a thin polarizing film for which market demand is increasing.
  • the width of the original film is not particularly limited, and can be, for example, 400 to 6000 mm.
  • the original film is prepared, for example, as a roll of a long polyvinyl alcohol-based resin film (original roll).
  • the polarizing film is produced by unwinding the long raw film from the raw roll and continuously conveying it along the film conveying route of the polarizing film manufacturing apparatus, and processing liquid contained in the processing tank (hereinafter referred to as A long polarizing film can be continuously produced by carrying out a drying step after carrying out a predetermined treatment step of immersing the film in a "treatment bath” and drawing it out.
  • the treatment process is not limited to the method of immersing the film in the treatment bath as long as it is a method of contacting the film with the treatment solution, and the treatment solution is attached to the film surface by spraying, flowing, dripping, or the like. It may also be a method of processing the film by allowing the When the treatment step is performed by immersing the film in a treatment bath, the treatment bath in which one treatment step is performed is not limited to one. One processing step may be completed.
  • the treatment liquid examples include a swelling liquid, a dyeing liquid, a cross-linking liquid, a complementary color liquid, a washing liquid, and the like. Then, as the above-mentioned treatment steps, a swelling step of contacting a swelling liquid to the raw film to perform a swelling treatment, a dyeing step of contacting a dyeing solution to the film after the swelling treatment and performing a dyeing process, and a dyeing process after the dyeing process A cross-linking step in which the film is brought into contact with a cross-linking solution to carry out cross-linking treatment, a complementary color step in which the complementary color solution is brought into contact with the film after cross-linking treatment to carry out complementary color treatment, and a cleaning solution is brought into contact with the film after the complementary color treatment.
  • washing steps to be performed are exemplified.
  • wet or dry uniaxial stretching treatment is performed.
  • Other processing steps may be added as desired.
  • the production method of the present invention includes a step of treating with a treatment solution containing nitrate, boric acid and zinc iodide and having a pH of 4.3 or higher at 25°C.
  • the processing liquid is usually an aqueous solution. Since the treatment liquid contains nitrate, boric acid and zinc iodide, it can be used for a cross-linking treatment for cross-linking the film after the dyeing treatment, and can also be used for a complementary color treatment for adjusting the hue of the film. Further, since the pH range of the treatment liquid is limited, it can also be used for pH adjustment treatment for adjusting the pH of the film.
  • the nitrate can contain at least one selected from the group consisting of aluminum nitrate, copper nitrate, sodium nitrate, potassium nitrate, zinc nitrate, and magnesium nitrate.
  • the nitrate comprises zinc nitrate.
  • the concentration of nitrate in the treatment liquid is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of water.
  • the concentration of nitrate is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less with respect to 100 parts by mass of water.
  • the concentration of chloride in the treatment liquid is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less with respect to 100 parts by mass of water.
  • the treatment liquid may be chloride-free.
  • FIG. 1 is a cross-sectional view schematically showing an example of a polarizing film manufacturing method and a polarizing film manufacturing apparatus used therein according to an embodiment of the present invention.
  • a raw film 10 made of a polyvinyl alcohol-based resin is continuously unwound from a raw roll 11 and conveyed along the film conveying route.
  • swelling bath swelling liquid contained in the swelling tank
  • dyeing bath dyeing liquid contained in the dyeing tank
  • cross-linking bath cross-linking liquid contained in the cross-linking tank
  • complementary color bath A complementary color liquid contained in a complementary color tank
  • cleaning bath a cleaning liquid contained in a cleaning tank
  • treatment tank is a general term including a swelling tank, a dyeing tank, a cross-linking tank, a complementary color tank and a washing tank
  • a “treatment liquid” is a swelling liquid, a dyeing liquid, a cross-linking liquid, a complementary color liquid and It is a general term including washing liquid
  • processing bath is a generic term including swelling bath, dyeing bath, cross-linking bath, complementary color bath and washing bath.
  • the swelling bath, the dyeing bath, the cross-linking bath, the complementary color bath, and the cleaning bath constitute the swelling section, the dyeing section, the cross-linking section, the complementary color section, and the cleaning section, respectively, in the manufacturing apparatus of this embodiment.
  • the film transport path of the polarizing film manufacturing apparatus includes guide rolls 30 to 48, 60, 61 that support the film to be transported or can change the film transport direction, and the film to be transported. It can be constructed by arranging nip rolls 50 to 55 at appropriate positions that can press and hold the and can apply a driving force to the film by its rotation, or can further change the film conveying direction. Guide rolls and nip rolls can be placed before, after, or in each treatment bath to allow the film to be introduced into, immersed in, and pulled out of the treatment bath (see FIG. 1). For example, the film can be immersed in each treatment bath by providing one or more guide rolls in each treatment bath and transporting the film along these guide rolls.
  • nip rolls are arranged before and after each treatment bath (nip rolls 50 to 54). It is possible to perform inter-roll stretching in which longitudinal uniaxial stretching is performed with a peripheral speed difference between rolls. Each step will be described below.
  • the swelling process is performed for the purpose of removing foreign matter from the surface of the raw film 10, removing the plasticizer in the raw film 10, imparting easy dyeability, plasticizing the raw film 10, and the like.
  • the processing conditions are determined within a range in which the object can be achieved and in which problems such as extreme dissolution or devitrification of the original film 10 do not occur.
  • raw film 10 is continuously unwound from raw film roll 11 and conveyed along a film conveying path, and raw film 10 is immersed in swelling bath 13 for a predetermined time. , and then withdrawing.
  • the raw film 10 is conveyed along the film conveying path constructed by the guide rolls 60 and 61 and the nip rolls 50 from when the raw film 10 is unwound until it is immersed in the swelling bath 13. be done.
  • the film is conveyed along a film conveying path constructed by guide rolls 30 to 32 and nip rolls 51 .
  • boric acid JP-A-10-153709
  • chloride JP-A-06-281816
  • inorganic acid inorganic salt
  • water-soluble organic solvent alcohol
  • the temperature of the swelling bath 13 is, for example, 10-50°C, preferably 10-40°C, more preferably 15-30°C.
  • the immersion time of the original film 10 is preferably about 10 to 300 seconds, more preferably 20 to 200 seconds.
  • the temperature of the swelling bath 13 is, for example, 20 to 70.degree. C., preferably 30 to 60.degree.
  • the immersion time of the original film 10 is preferably 30 to 300 seconds, more preferably 60 to 240 seconds.
  • the original film 10 tends to swell in the width direction, causing the film to wrinkle.
  • a roll having a widening function such as an expander roll, a spiral roll, or a crown roll is used as the guide rolls 30, 31 and/or 32, or a cross guider or bend bar is used.
  • a stretching treatment is to apply a stretching treatment.
  • the uniaxial stretching process can be performed in the swelling bath 13 by utilizing the peripheral speed difference between the nip rolls 50 and 51 .
  • the film swells and expands also in the transport direction of the film. Therefore, if the film is not actively stretched, it is placed, for example, before and after the swelling bath 13 in order to eliminate the slack of the film in the transport direction. It is preferable to take measures such as controlling the speed of the nip rolls 50 and 51 .
  • the water flow in the swelling bath 13 is controlled by an underwater shower, or an EPC device (edge position control device: detects the edge of the film and detects the meandering of the film). It is also useful to use a device that prevents
  • the film pulled out from the swelling bath 13 passes through the guide roll 32, the nip roll 51 and the guide roll 33 in order and is introduced into the dyeing bath 15.
  • the dyeing step is performed for the purpose of adsorbing and orienting the dichroic dye on the polyvinyl alcohol-based resin film after the swelling treatment.
  • the processing conditions are determined within a range in which the object can be achieved and in which problems such as extreme dissolution or devitrification of the film do not occur.
  • the film is conveyed along a film conveying path constructed by nip roll 51, guide rolls 33 to 36 and nip roll 52, and the film after swelling is stored in dyeing bath 15 (dyeing tank). It can be carried out by immersing the substrate in the treatment solution for a predetermined period of time and then withdrawing it.
  • the film subjected to the dyeing process is preferably a film that has been uniaxially stretched to at least some degree, or instead of the uniaxial stretching process before the dyeing process, or In addition to the uniaxial stretching treatment before the dyeing treatment, it is preferable to perform the uniaxial stretching treatment during the dyeing treatment.
  • Certain aqueous solutions can be used.
  • potassium iodide other iodides such as zinc iodide may be used, or potassium iodide and other iodides may be used in combination.
  • Compounds other than iodide, such as boric acid, zinc chloride, and cobalt chloride, may coexist.
  • boric acid When boric acid is added, it is distinguished from the cross-linking treatment and complementary color treatment described later in that it contains iodine. It can be regarded as a dyeing bath 15 .
  • the temperature of the dyeing bath 15 when the film is immersed is usually 10 to 45° C., preferably 10 to 40° C., more preferably 20 to 35° C., and the immersion time of the film is usually 30 to 600 seconds. It is preferably 60 to 300 seconds.
  • the dyeing solution in the dyeing bath 15 has a concentration of, for example, a dichroic dye/water in mass ratio of about 0.001 to 0.1/100.
  • Aqueous solutions can be used.
  • the dyeing bath 15 may contain a dyeing assistant or the like, and may contain, for example, an inorganic salt such as sodium sulfate or a surfactant. Only one type of dichroic dye may be used alone, or two or more types of dichroic dyes may be used in combination.
  • the temperature of the dyeing bath 15 when the film is immersed is, for example, 20 to 80° C., preferably 30 to 70° C., and the immersion time of the film is usually 30 to 600 seconds, preferably 60 to 300 seconds.
  • the film can be uniaxially stretched in the dyeing bath 15 as described above.
  • the uniaxial stretching of the film can be performed by a method such as creating a peripheral speed difference between the nip rolls 51 and 52 arranged before and after the dyeing bath 15 .
  • the guide rolls 33, 34, 35 and/or 36 are provided with expander rolls, spiral rolls, crown rolls, etc., in order to convey the polyvinyl alcohol resin film while removing wrinkles of the film.
  • Rolls with a widening function can be used, or other widening devices such as cross guiders, bend bars, tenter clips can be used.
  • Another means for suppressing the occurrence of wrinkles is to apply stretching treatment, as in the case of swelling treatment.
  • the film pulled out from the dyeing bath 15 passes through the guide roll 36, the nip roll 52, and the guide roll 37 in order and is introduced into the cross-linking bath 17.
  • the cross-linking step is a process of cross-linking the film to improve water resistance and the like.
  • the film is transported along a film transport path constructed by nip roll 52, guide rolls 37 to 40, and nip roll 53a, and dyed in cross-linking bath 17 (cross-linking liquid contained in cross-linking bath). It can be carried out by immersing the treated film for a predetermined time and then withdrawing it.
  • cross-linking liquid a solution in which a cross-linking agent is dissolved in a solvent can be used.
  • cross-linking agents include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination of two or more.
  • solvent for example, water can be used, and an organic solvent compatible with water may be included.
  • concentration of the cross-linking agent in the cross-linking solution is, but not limited to, preferably in the range of 1 to 20% by mass, more preferably 6 to 15% by mass.
  • the cross-linking liquid may be an aqueous solution containing, for example, about 1 to 10 parts by mass of boric acid per 100 parts by mass of water.
  • the cross-linking liquid preferably contains iodide in addition to boric acid, and the amount thereof is, for example, 1 to 30 parts by weight per 100 parts by weight of water.
  • iodides include potassium iodide and zinc iodide. Two or more iodides may be included. Compounds other than iodide, such as sodium thiosulfate, potassium sulfite, sodium sulfate, etc., may also coexist.
  • nitrates may coexist.
  • the nitrate can contain at least one selected from the group consisting of aluminum nitrate, copper nitrate, sodium nitrate, potassium nitrate, zinc nitrate, and magnesium nitrate.
  • the nitrate comprises zinc nitrate.
  • the concentrations of boric acid and iodide and the temperature of the cross-linking bath 17 can be appropriately changed depending on the purpose.
  • the temperature of the cross-linking bath 17 when the film is immersed is usually 50 to 70° C., preferably 53 to 65° C., and the film immersion time is usually 10 to 600 seconds, preferably 20 to 300 seconds, more preferably 20 to 200 seconds.
  • the temperature of the cross-linking bath 17 is usually 50 to 85°C, preferably 55 to 80°C.
  • the cross-linking treatment may be performed multiple times, for example, 2 to 5 times.
  • the composition and temperature of each cross-linking bath used may be the same or different within the above ranges.
  • the uniaxial stretching treatment can also be performed in the cross-linking bath 17 by utilizing the peripheral speed difference between the nip roll 52 and the nip roll 53a.
  • the guide rolls 37, 38, 39 and/or 40 are provided with expander rolls, spiral rolls, crown rolls, etc., in order to convey the polyvinyl alcohol resin film while removing wrinkles of the film.
  • Other widening devices such as cross guiders, bend bars, tenter clips, etc. can be used.
  • Another means for suppressing the occurrence of wrinkles is to apply stretching treatment, as in the case of swelling treatment.
  • the complementary color process is a process for adjusting the hue of the film.
  • the film is transported along a film transport path constructed by nip roll 53a, guide rolls 41 to 44, and nip roll 53b, and is crosslinked in complementary color bath 18 (complementary color liquid stored in complementary color tank). It can be carried out by immersing the post-processed film for a predetermined period of time and then withdrawing it.
  • the complementary color liquid may be an aqueous solution containing, for example, about 1 to 10 parts by mass of boric acid per 100 parts by mass of water.
  • Complementary color liquid when the dichroic dye used in the dyeing treatment is iodine, preferably contains iodide in addition to boric acid, and the amount thereof is, for example, 1 to 30 parts by weight with respect to 100 parts by weight of water.
  • iodides include potassium iodide and zinc iodide. Two or more iodides may be included.
  • Compounds other than iodide, such as sodium thiosulfate, potassium sulfite, and sodium sulfate may also coexist. Moreover, you may coexist nitrate.
  • the nitrate can contain at least one selected from the group consisting of aluminum nitrate, copper nitrate, sodium nitrate, potassium nitrate, zinc nitrate, and magnesium nitrate.
  • the nitrate comprises zinc nitrate.
  • the temperature of the complementary color bath 18 when the film is immersed is usually 10 to 45° C., and the film immersion time is usually 1 to 300 seconds, preferably 2 to 100 seconds.
  • Complementary color processing may be performed multiple times, for example, 2 to 5 times.
  • the composition and temperature of each complementary color bath to be used may be the same or different within the above ranges.
  • the uniaxial stretching treatment can be applied in the complementary color bath 18 by utilizing the peripheral speed difference between the nip rolls 53a and 53b.
  • the guide rolls 41, 42, 43 and/or 44 are provided with expander rolls, spiral rolls, crown rolls, etc., in order to convey the polyvinyl alcohol resin film while removing wrinkles of the film.
  • Rolls with a widening function can be used, or other widening devices such as cross guiders, bend bars, tenter clips can be used.
  • Another means for suppressing the occurrence of wrinkles is to apply stretching treatment, as in the case of swelling treatment.
  • the film pulled out from the complementary color bath 18 passes through the guide roll 44 and the nip roll 53b in order and is introduced into the cleaning bath 19.
  • the example shown in FIG. 1 includes a washing step after the complementary color step.
  • the cleaning treatment is performed for the purpose of removing excess chemicals such as boric acid and iodine adhering to the polyvinyl alcohol-based resin film.
  • the cleaning step is performed by, for example, immersing the polyvinyl alcohol-based resin film that has undergone complementary color treatment in the cleaning bath 19 .
  • the cleaning step is performed by spraying the film with the cleaning solution as a shower instead of immersing the film in the cleaning bath 19, or by combining immersion in the cleaning bath 19 and spraying the cleaning solution. can also
  • FIG. 1 shows an example in which a polyvinyl alcohol-based resin film is immersed in a cleaning bath 19 for cleaning treatment.
  • the temperature of the washing bath 19 in the washing treatment is usually 2 to 40° C., and the immersion time of the film is usually 2 to 120 seconds.
  • the guide rolls 45, 46, 47 and/or 48 are rolls having a widening function such as expander rolls, spiral rolls and crown rolls. can be used, or other widening devices such as cross guiders, bend bars, tenter clips can be used. Further, in the film washing treatment, a stretching treatment may be applied to suppress the generation of wrinkles.
  • the raw film 10 is uniaxially stretched wet or dry during the series of treatment steps (that is, before and after any one or more treatment steps and/or during any one or more treatment steps). It is processed.
  • a specific method of uniaxial stretching treatment is, for example, between two nip rolls (for example, two nip rolls arranged before and after the treatment bath) that constitute the film conveying path, and longitudinal uniaxial stretching is performed by applying a peripheral speed difference between the rolls. Stretching can be hot roll stretching, tenter stretching, etc. as described in Japanese Patent No. 2731813, preferably roll-to-roll stretching.
  • the uniaxial stretching process can be performed multiple times from raw film 10 to polarizing film 23 . As described above, the stretching treatment is also advantageous in suppressing the generation of wrinkles in the film.
  • the final cumulative draw ratio of the polarizing film 23 based on the original film 10 is usually 4.5 to 7 times, preferably 5 to 6.5 times.
  • the stretching process may be carried out in any treatment process, and even when the stretching treatment is carried out in two or more treatment processes, the stretching treatment may be carried out in any treatment process.
  • the treatment step is a step of bringing the film into contact with a treatment liquid containing nitrate, boric acid and zinc iodide and having a pH of 4.3 or higher at 25°C.
  • the pH of the treatment liquid at 25° C. is preferably 4.6 or higher, preferably 4.7 or higher, and more preferably 4.8 or higher.
  • the pH of the treatment liquid at 25° C. is preferably 6.8 or less, more preferably 6.5 or less, and even more preferably 6.3 or less.
  • the processing step is, for example, the complementary color step described above. When the treatment process is a complementary color process, the above description of the complementary color process can be directly applied to the description of the process process.
  • the treatment liquid contains nitrate, boric acid and zinc iodide, and has a pH of 4.3 or higher.
  • the treatment liquid may contain, for example, 1 to 20 parts by mass of potassium iodide with respect to 100 parts by mass of water.
  • the treatment liquid usually further contains a pH adjuster.
  • pH adjusters include inorganic bases such as potassium hydroxide and sodium hydroxide.
  • the treatment liquid can be adjusted to have a pH of 4.3 or more at 25° C. by adjusting the amount of the pH adjuster added.
  • the effect of suppressing yellowing when an interlayer filling structure is adopted is excellent even in a high temperature environment exceeding 95 ° C. by having a treatment step, and the single transmittance when not using an interlayer filling structure is improved. It is possible to provide a polarizing film that can effectively suppress the decrease.
  • the method for producing a polarizing film may include a second treatment step.
  • This is the step of contacting the film with a second processing liquid containing nitrate, boric acid and iodide and having a pH of less than 4.3 at 25°C.
  • the second treatment step is, for example, the cross-linking step described above.
  • the second treatment step is a cross-linking step, the above description of the cross-linking step can be directly applied to the description of the second treatment step.
  • the second treatment liquid contains nitrate, boric acid and iodide, and has a pH of less than 4.3 at 25°C.
  • the added amounts of nitrate, boric acid, and iodide may be adjusted to make the pH less than 4.3, or an acid (pH adjuster) may be added to lower the pH at 25°C. It may be less than 4.3.
  • the second treatment liquid is preferably adjusted to have a pH of less than 4.3 at 25° C. by adjusting the amount of boric acid added.
  • the second treatment step is preferably performed before the treatment step, and the second treatment step and the treatment step are preferably performed in this order.
  • the film manufacturing method includes a washing step, it is preferable that the second treatment step, the treatment step, and the washing step are performed in this order.
  • the second treatment process and the treatment process are, for example, a cross-linking process and a complementary color process, a first complementary color process and a second complementary color process, a first cross-linking process and a second cross-linking process, and the like.
  • Drying of the film is not particularly limited, but can be performed using a drying oven 21 as in the example shown in FIG.
  • the drying oven 21 may be equipped with, for example, a hot air dryer.
  • the drying temperature is, for example, 30 to 100° C.
  • the drying time is, for example, 30 to 600 seconds.
  • the treatment for drying the polyvinyl alcohol-based resin film can also be performed using a far-infrared heater.
  • Processing other than the processing described above can also be added.
  • treatments that may be added include immersion in aqueous iodide solutions without boric acid.
  • the polarizing film obtained as described above may be sequentially wound on a winding roll to form a roll, or may be directly subjected to a polarizing plate manufacturing method without being wound.
  • the roll-shaped polarizing film can then be subjected to a method for producing a polarizing plate.
  • One aspect of the method for producing a polarizing plate includes a bonding step of bonding a protective film to one side or both sides of a polarizing film via a bonding layer.
  • the polarizing film according to the present embodiment is obtained by dyeing a polyvinyl alcohol-based resin film with a dichroic dye.
  • the thickness of the polarizing film is preferably 5 ⁇ m or more and 60 ⁇ m or less, more preferably 7 ⁇ m or more and 30 ⁇ m or less.
  • the visibility correction single transmittance Ty of the polarizing plate is preferably 35 to 47%, more preferably 36 to 45%.
  • the visibility correction polarization degree Py is preferably 99.9% or more, more preferably 99.95% or more.
  • a polarizing film constituting such a polarizing plate can be obtained by the manufacturing method described above.
  • the chlorine content of the polarizing film can be, for example, 900 ppm or less. Although the lower limit is not limited, the chlorine content of the polarizing film can be 0 ppm or more. The chlorine content of the polarizing film may be 0 ppm. The chlorine content of the polarizing film can be reduced by reducing the amount of chloride in the processing solution used in the manufacturing process of the polarizing film.
  • the polarizing plate according to this embodiment can be obtained by laminating a protective film on one side or both sides of the polarizing film via a lamination layer.
  • Protective films include, for example, films made of acetylcellulose-based resins such as triacetylcellulose and diacetylcellulose; films made of polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; polycarbonate-based resin films, cyclo Olefin-based resin films; acrylic-based resin films; and films made of linear olefin-based resins such as polypropylene-based resins.
  • the bonding surface of the polarizing film and/or the protective film is subjected to corona treatment, flame treatment, plasma treatment, ultraviolet irradiation, primer coating treatment, saponification treatment, etc. may be treated.
  • the bonding layer interposed between the polarizing film and the protective film can be formed using an adhesive or pressure-sensitive adhesive.
  • an active energy ray-curable adhesive such as an ultraviolet-curable adhesive, an aqueous solution of a polyvinyl alcohol-based resin, or an aqueous solution in which a cross-linking agent is added thereto, and a water-based adhesive such as a urethane-based emulsion adhesive. agents can be mentioned.
  • a zinc compound such as zinc nitrate may be added to the water-based adhesive.
  • the UV-curable adhesive may be a mixture of an acrylic compound and a photoradical polymerization initiator, a mixture of an epoxy compound and a photocationic polymerization initiator, or the like.
  • a cationic polymerizable epoxy compound and a radically polymerizable acrylic compound can be used together, and a photocationic polymerization initiator and a photoradical polymerization initiator can be used together as initiators.
  • a polarizing plate can be used in an image display device.
  • image display elements used in image display devices include liquid crystal display elements and organic EL display elements.
  • the polarizing plate according to the present invention may be used by being placed on the viewing side, may be used by being placed on the backlight side, or may be used on both the viewing side and the backlight side. may be used for
  • the image display device of the present invention can be used for mobile devices such as televisions, personal computers, mobile phones, tablet terminals, etc. In addition, it has a high inhibitory effect on yellowing in a high-temperature environment or a high inhibitory effect on a decrease in single transmittance. and can exhibit a stable image display function for a long period of time.
  • Vehicle applications include, for example, car navigation devices, speedometers, touch panels for air conditioners, image display devices used for back monitors and rear monitors, and the like.
  • Example 1 (1) Production of Polarizing Film 1 A polarizing film of Example 1 was produced from a polyvinyl alcohol-based resin film using the production apparatus shown in FIG. Specifically, a long polyvinyl alcohol (PVA) raw film with a thickness of 45 ⁇ m [trade name “VF-PE#4500” manufactured by Kuraray Co., Ltd., saponification degree of 99.9 mol% or more] was wound from a roll. The film was continuously transported while being discharged, immersed in a swelling bath made of pure water at 23° C. for 110 seconds, and uniaxially stretched by 2.1 times (swelling step). After that, the film pulled out from the swelling bath was immersed in a 23° C.
  • PVA polyvinyl alcohol
  • the film pulled from the cross-linking bath was 0.55/1.76/2.7/5.0/100 (weight
  • the film was immersed in a complementary color bath at 45° C. for 14 seconds and uniaxially stretched to 1.02 times (complementary color step, treatment step).
  • the pulled out film was dried by staying in a drying oven at a temperature of 55° C. for 90 seconds (drying step).
  • the complementary color liquid had a pH of 4.30 at 25°C.
  • the thickness of the obtained polarizing film 1 was 19 ⁇ m.
  • Adhesive 1 50 parts by mass of a modified PVA-based resin containing an acetoacetyl group ("Gohsenex Z-410" manufactured by Mitsubishi Chemical Corporation) was dissolved in 950 parts by mass of pure water and heated at 90°C for 2 hours. After heating, the mixture was cooled to room temperature to obtain a PVA solution for adhesive (hereinafter referred to as "PVA solution A").
  • PVA solution A a PVA solution for adhesive
  • Adhesive 1 was prepared by blending PVA solution A prepared above, pure water, 40% by mass glyoxal solution, and methanol so as to have the following content per 100 parts by mass of adhesive.
  • PVA content 3 parts by mass
  • Methanol content 36 parts by mass
  • Glyoxal content 0.3 parts by mass
  • Pure water 60.7 parts by mass
  • Transparent Protective Film 1 A commercially available cellulose acylate film “TD40N” (manufactured by Fujifilm Corporation, thickness 40 ⁇ m) was immersed in a 1.5 mol/L NaOH aqueous solution (saponification solution) maintained at 55° C. for 2 minutes. After soaking, the film was washed with water. Thereafter, the film was immersed in a 0.05 mol/L sulfuric acid aqueous solution at 25° C. for 30 seconds, and then passed through a washing bath under running water for 30 seconds to neutralize the film. After removing the water by repeating water removal with an air knife three times, the film was dried by staying in a drying zone at 70° C. for 15 seconds to prepare a saponified film.
  • ⁇ Comparative Example 1> Production of polarizing film 2 The same processes as in Example 1 were performed up to the stretching and cross-linking steps. Subsequently, the film withdrawn from the cross-linking bath was hydroxylated in a solution of zinc nitrate hexahydrate/potassium iodide/boric acid/water at a weight ratio of 2.20/2.7/5.0/100. The film was immersed in a 45° C. complementary color bath consisting of a complementary color solution containing an aqueous potassium solution for an immersion time of 14 seconds, and uniaxially stretched by 1.02 times (complementary color process, treatment process). Subsequently, the pulled out film was dried by staying in a drying oven at a temperature of 55° C. for 90 seconds (drying step). The complementary color liquid had a pH of 3.40 at 25°C. The thickness of the obtained polarizing film 2 was 19 ⁇ m.
  • High temperature durability evaluation-yellow index YI- An acrylic pressure-sensitive adhesive (manufactured by Lintec Corporation, product number “#7”) was formed on both sides of the polarizing plates 1 and 2 with adjusted water content. Furthermore, it is cut into a size of 110 mm ⁇ 60 mm so that the absorption axis of the polarizing plate is parallel to the long side.
  • An evaluation sample was prepared by laminating. The samples for evaluation were autoclaved for 15 minutes under conditions of 50° C. and 5 atm, and then exposed to an environment of 105° C. for 168 hours to perform a high temperature durability test. The YI of the polarizing plate 1 was 46 after 168 hours had passed.
  • the YI of the polarizing plate 2 was 40 after 168 hours had passed. Both the polarizing plate 1 and the polarizing plate 2 had a YI of 50 or less after 168 hours, and although they were chlorine-free, they were found to exhibit excellent high-temperature durability evaluation from the viewpoint of YI.
  • Polarizing plate 1 was able to reduce the amount of change in single transmittance after the high temperature endurance test.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Polarising Elements (AREA)
  • Treatments Of Macromolecular Shaped Articles (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
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JP2015075762A (ja) * 2013-10-07 2015-04-20 東友ファインケム株式会社 偏光子の製造方法
WO2016117659A1 (ja) * 2015-01-23 2016-07-28 住友化学株式会社 偏光子及びその製造方法
WO2017078092A1 (ja) * 2015-11-05 2017-05-11 住友化学株式会社 偏光子及びその製造方法
WO2019103002A1 (ja) * 2017-11-24 2019-05-31 日東電工株式会社 偏光子および偏光板
WO2020066318A1 (ja) * 2018-09-28 2020-04-02 日東電工株式会社 偏光子の製造方法
JP6695014B1 (ja) * 2018-11-12 2020-05-20 日東電工株式会社 偏光膜、偏光フィルム、積層偏光フィルム、画像表示パネル、および画像表示装置、ならびに偏光膜の製造方法
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06254958A (ja) * 1993-03-03 1994-09-13 Nippon Synthetic Chem Ind Co Ltd:The ポリビニルアルコール系樹脂延伸フィルム
WO2006095815A1 (ja) * 2005-03-10 2006-09-14 Nippon Kayaku Kabushiki Kaisha ヨウ素系偏光フィルム、その製造方法及びそれを用いた偏光板
JP2015075762A (ja) * 2013-10-07 2015-04-20 東友ファインケム株式会社 偏光子の製造方法
WO2016117659A1 (ja) * 2015-01-23 2016-07-28 住友化学株式会社 偏光子及びその製造方法
WO2017078092A1 (ja) * 2015-11-05 2017-05-11 住友化学株式会社 偏光子及びその製造方法
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WO2020066318A1 (ja) * 2018-09-28 2020-04-02 日東電工株式会社 偏光子の製造方法
JP6695014B1 (ja) * 2018-11-12 2020-05-20 日東電工株式会社 偏光膜、偏光フィルム、積層偏光フィルム、画像表示パネル、および画像表示装置、ならびに偏光膜の製造方法
JP2021067873A (ja) * 2019-10-25 2021-04-30 住友化学株式会社 偏光フィルムの製造方法および製造装置

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