WO2016203909A1 - Production method for stretched film - Google Patents

Production method for stretched film Download PDF

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Publication number
WO2016203909A1
WO2016203909A1 PCT/JP2016/065260 JP2016065260W WO2016203909A1 WO 2016203909 A1 WO2016203909 A1 WO 2016203909A1 JP 2016065260 W JP2016065260 W JP 2016065260W WO 2016203909 A1 WO2016203909 A1 WO 2016203909A1
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Prior art keywords
film
humidified
chamber
movable guide
humidifier
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PCT/JP2016/065260
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French (fr)
Japanese (ja)
Inventor
勉 古谷
武藤　清
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住友化学株式会社
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Publication of WO2016203909A1 publication Critical patent/WO2016203909A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • 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 producing a stretched film from a long polyvinyl alcohol-based resin film.
  • the polarizing plate is widely used as a polarizing element in an image display device such as a liquid crystal display device.
  • a polarizing plate the thing of the structure which bonded the transparent resin film (protective film etc.) on the single side
  • the polarizing film is mainly immersed in a dye bath containing a dichroic dye such as iodine, and then immersed in a cross-linking bath containing a cross-linking agent such as boric acid, with respect to the raw film made of polyvinyl alcohol resin.
  • the film is produced by uniaxially stretching the film at any stage. Uniaxial stretching includes dry stretching in which stretching is performed in the air before the immersion treatment and wet stretching in which stretching is performed in a liquid such as the dyeing bath and the crosslinking bath.
  • the polyvinyl alcohol-based resin film used for dry stretching may be adjusted in moisture content in order to improve stretchability.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2002-333521
  • Patent Document 1 describes that the moisture content of a polyvinyl alcohol-based resin film subjected to dry stretching is 10% or less by drying (paragraph [0016]).
  • Patent Document 2 a polyvinyl alcohol film is manufactured by casting, and then water vapor is sprayed from both sides of the film in a humidity controller. It describes that a humidity control (humidification) treatment is performed (paragraph [0057]).
  • An object of the present invention is to provide a method for producing a stretched film using a polyvinyl alcohol-based resin film whose moisture content is adjusted by a new method.
  • This invention provides the manufacturing method of the stretched film shown below.
  • the humidifier includes a chamber capable of adjusting an internal relative humidity, and a plurality of guide rolls that are disposed in the chamber and define a conveyance path of the polyvinyl alcohol-based resin film, At least one of the plurality of guide rolls is a movable guide roll capable of moving the position,
  • the process according to [1], wherein the step of adjusting the moisture content includes adjusting a position of the movable guide roll.
  • the step of obtaining the humidified film includes Detecting the moisture content of the humidified film derived from the humidifier; A step of controlling the position of the movable guide roll based on the detection result obtained in the detecting step;
  • the chamber includes a first chamber on a side where the polyvinyl alcohol-based resin film is introduced, and a second chamber on a side where the humidified film is led out.
  • the manufacturing method according to any one of [2] to [5], wherein the relative humidity in the second room is higher than the relative humidity in the first room.
  • each of the first chamber and the second chamber includes the movable guide roll.
  • Step S10 for obtaining a humidified film is a step for obtaining a humidified film by continuously introducing a long PVA film into the humidifier, and referring to FIG. 1, the transport path of the PVA film in the humidifier Step S101 for adjusting the moisture content of the humidified film by changing the length is included.
  • Polyvinyl alcohol-based resin film As the polyvinyl alcohol-based resin constituting the PVA film, a saponified polyvinyl acetate-based resin can be used.
  • the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith.
  • examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.
  • “(Meth) acryl” represents at least one selected from the group consisting of acryl and methacryl. The same applies to other terms with “(meta)”.
  • the degree of saponification of the polyvinyl alcohol-based resin can be in the range of 80.0 to 100.0 mol%, preferably in the range of 90.0 to 100.0 mol%, more preferably 98.0. It is in the range of ⁇ 100.0 mol%.
  • the saponification degree is less than 80.0 mol%, when the obtained stretched film is used as a raw material for the polarizing film, the water resistance and wet heat resistance of the polarizing plate including the polarizing film can be lowered.
  • the degree of saponification is the unit ratio (mol%) of the ratio of acetate groups (acetoxy groups: —OCOCH 3 ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, to hydroxyl groups by the saponification process.
  • the following formula: Degree of saponification (mol%) 100 ⁇ (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups) Defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.
  • the average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and further preferably 2000 to 5000.
  • the average degree of polymerization of the polyvinyl alcohol resin can also be determined according to JIS K 6726 (1994).
  • JIS K 6726 (1994) When the average degree of polymerization is less than 100, when the obtained stretched film is used as a raw material for the polarizing film, it is difficult to obtain a polarizing film having a preferable polarizing performance, and when it exceeds 10,000, the solubility in a solvent deteriorates. Film formation can be difficult.
  • the PVA film is obtained by forming the polyvinyl alcohol resin described above.
  • the film forming method is not particularly limited, and a known method such as a melt extrusion method or a solvent casting method can be employed.
  • the thickness of the PVA film is, for example, about 10 to 150 ⁇ m, preferably 100 ⁇ m or less, more preferably 65 ⁇ m or less, still more preferably 50 ⁇ m or less, and particularly preferably 35 ⁇ m or less (for example, 30 ⁇ m or less, further 20 ⁇ m or less).
  • the PVA film can contain additives such as a plasticizer.
  • a plasticizer are polyhydric alcohols, and specific examples thereof include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, triglycerin, tetraethylene glycol, trimethylolpropane, polyethylene glycol and the like.
  • the PVA film can contain one or more plasticizers.
  • the content of the plasticizer is usually 5 to 20 parts by weight, preferably 7 to 15 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin constituting the PVA film.
  • FIG. 2 is a schematic cross-sectional view showing an example of a humidifier suitably used in step S10 for obtaining a humidified film and a humidifying system including the humidifier.
  • the humidifying device 3 shown in FIG. 2 is a device for continuously humidifying the long PVA film 1 (increasing the moisture content), and includes a chamber 4 capable of adjusting the internal relative humidity.
  • the chamber 4 has an introduction port 5 for introducing the long PVA film 1 to be humidified into the chamber 4 and an outlet port 6 for deriving the humidified film (humidified film) 2 from the chamber 4. And have.
  • a plurality of guide rolls 7 and 8 are arranged in the chamber 4. These guide rolls 7 and 8 are rolls for guiding the PVA film 1 in the chamber 4, and define a conveyance path of the PVA film 1 in the chamber 4.
  • the PVA film 1 continuously introduced into the chamber 4 in the humidified environment from the introduction port 5 is continuously along the conveyance path (in a state of being wound around the outer periphery of the guide rolls 7 and 8). Be transported. In this conveyance process, the PVA film 1 is humidified by being placed in a chamber 4 in a humidified environment for a certain residence time.
  • the humidified film 2 is continuously led out from the outlet 6 and subjected to step S20 to obtain the next stretched film.
  • the humidified film 2 led out from the outlet 6 may be temporarily wound into a roll shape, and then the humidified film 2 may be unwound from the film roll to be subjected to step S20 to obtain a stretched film.
  • the humidified film 2 is subjected to step S20 to obtain a stretched film without being wound once.
  • the guide roll group installed in the chamber 4 includes a movable guide roll 8 (two in the example of FIG. 2) whose position can be moved, and a non-movable guide roll 7 (FIG. 3 in the example of 2).
  • the “movable guide roll capable of position movement” refers to a guide roll that can move the position of the rotation axis of the guide roll in the chamber 4.
  • the non-movable guide roll 7 and the movable guide roll 8 may be independently a drive roll or a free roll.
  • the driving roll is a roll that can give a driving force for film conveyance to a film that contacts the roll.
  • the free roll is a roll that simply plays a role of supporting a traveling film and cannot give a driving force for film conveyance.
  • the transport path length of the PVA film 1 in the humidifier 3 can be freely changed by adjusting the position of the movable guide roll 8.
  • the change of the conveyance path length of the PVA film 1 means the change of the residence time in the humidifier 3 (chamber 4). Therefore, the humidified state (moisture ratio) of the obtained humidified film 2 can be controlled by adjusting the position of the movable guide roll 8. That is, in the case of using the humidifying device 3, the step S ⁇ b> 101 for adjusting the moisture content of the humidifying film 2 includes adjusting the position of at least one movable guide roll 8 included in the humidifying device 3.
  • Conventional film humidifiers generally adjust the humidified state (moisture ratio) of the obtained humidified film by controlling the humidification environment in the humidifier, as described in Patent Document 2 above.
  • the humidifying device 3 since the transport path length of the PVA film 1 in the chamber 4 and thus the residence time can be changed in a short time, the humidified state of the humidified film 2 (water content) ) Is not in the desired state, or when the desired humidification state (water content) is changed, the humidified film 2 having the desired humidification state (water content) can be provided in a short time. . Further, according to the humidifying device 3 that changes the transport path length by moving the position of the movable guide roll 8, the transport path length and accordingly the residence time can be precisely controlled. Can be adjusted precisely. The precise adjustment of the moisture content can improve the stretchability (especially the suitability for dry stretching) of the PVA film 1 in step S20 for obtaining a stretched film.
  • the number of the non-movable guide rolls 7 and the movable guide rolls 8 included in the humidifying device 3 is not limited to the example of FIG. All of the guide rolls provided in the humidifying device 3 may be the movable guide rolls 8.
  • the humidifier 3 has two or more movable guide rolls 8 because the change in the transport path length (difference between the maximum transport path length and the minimum transport path length) can be increased and the transport path length can be more precisely controlled. It is preferable.
  • the position of the movable guide roll 8 can be moved using a mechanism such as a ball screw, a hydraulic cylinder, a pneumatic cylinder, a hydraulic cylinder, an electric cylinder, or a linear actuator.
  • a mechanism such as a ball screw, a hydraulic cylinder, a pneumatic cylinder, a hydraulic cylinder, an electric cylinder, or a linear actuator.
  • the position movement of the movable guide roll 8 is a position movement that can change the transport path length of the PVA film 1 as shown in FIG. 2, for example. Including.
  • the parallel movement means that the rotation axis of the movable guide roll 8 before and after the position movement is parallel.
  • the direction of movement of the movable guide roll 8 is not particularly limited. For example, when the horizontal direction is used as a reference, it may be parallel to the horizontal direction as shown in FIG. 3 or horizontal as shown in FIG. The direction may be inclined from the direction.
  • these movable guide rolls 8 may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
  • the moving direction of the movable guide roll 8 is inclined from the horizontal direction.
  • a preferred example of the direction inclined from the horizontal direction is the vertical direction. That is, in this case, the movable guide roll 8 is a roll that can be raised and lowered in the vertical direction (vertical direction).
  • the transport direction of the PVA film 1 can be horizontal, and in the lead-out of the humidified film 2 from the chamber 4, the transport direction of the humidified film 2 is also horizontal.
  • the vertical direction is a direction perpendicular to the transport direction of the PVA film 1 or the humidified film 2.
  • the chamber 4 can adjust the internal relative humidity by adjusting the internal moisture.
  • the PVA film 1 By continuously passing the long PVA film 1 through the chamber 4, the PVA film 1 can be continuously humidified (increase in the moisture content).
  • the relative humidity in the chamber 4 can be set according to the desired humidified state (moisture ratio) of the humidified film 2.
  • the relative humidity in the chamber 4 is, for example, 20% or more, preferably 30% or more, and may be 40% or more.
  • the relative humidity is usually 99% or less, preferably 95% or less. If the relative humidity is too high, condensation may occur on the surface of the PVA film 1 depending on the temperature of the PVA film 1. When condensation occurs on the surface of the PVA film 1, the temperature of the PVA film 1 does not rise to a desired value in the condensation portion due to the latent heat of evaporation of water, and as a result, the desired humidified state (moisture ratio) does not occur in the condensation portion. Sometimes. Moreover, when dew condensation occurs on the surface of the PVA film 1, dew marks are generated later, which may adversely affect the appearance quality of the humidified film 2, and thus the stretched film and the polarizing film. Condensation traces are dry traces that remain after condensation has formed and dried.
  • the chamber 4 is preferably capable of adjusting the internal temperature together with the internal relative humidity.
  • the internal temperature can be increased by supplying hot air or the like.
  • an infrared heater, a halogen heater, a panel heater, or the like is used instead of or in combination with hot air, or a hot roll is used as at least one of the guide rolls 7 and 8. You can also.
  • the term “heat roll” as used herein refers to a roll provided with a heat source (for example, a heat medium such as warm water or an infrared heater) to increase the surface temperature.
  • the internal temperature of the chamber 4 when the PVA film 1 is humidified and the temperature of the PVA film 1 are usually 35 ° C. or higher, preferably 40 ° C. or higher, more preferably 45 ° C. or higher.
  • the efficiency of the humidification treatment can be increased.
  • the internal temperature of the chamber 4 and the temperature of the PVA film 1 are preferably 150 ° C. or less, and 130 ° C. More preferably, it is 100 degrees C or less, It is more preferable that it is 90 degrees C or less.
  • the residence time of the PVA film 1 in the chamber 4 can be controlled by adjusting the position of the movable guide roll 8 according to the humidified state (moisture content) of the humidified film 2 desired.
  • the residence time of the PVA film 1 is, for example, about 5 to 500 seconds.
  • FIG. 4 is a schematic cross-sectional view showing another example of a humidifier and a humidifying system including the humidifier suitably used in step S10 for obtaining a humidified film.
  • the humidifying device 3 shown in FIG. 4 has the same configuration as the humidifying device 3 shown in FIG. 2 except that it includes a chamber composed of a plurality of chambers.
  • the chamber is composed of a first chamber 4 a including the inlet 5 for the PVA film 1 and a second chamber 4 b including the outlet 6 for the humidified film 2.
  • the first chamber 4a and the second chamber 4b are capable of independently adjusting the indoor relative humidity, and are preferably capable of adjusting the internal temperature together with the indoor relative humidity.
  • each of the first chamber 4a and the second chamber 4b includes at least one movable guide roll 8 described above so that the transport path length of the PVA film 1 in each chamber can be freely changed.
  • All of the guide rolls provided in the first chamber 4a may be the movable guide roll 8, and all of the guide rolls provided in the second chamber 4b may be the movable guide roll 8.
  • the first chamber 4a and the second chamber 4b each have two or more movable guide rolls 8 because the change in the transfer path length can be further increased and the transfer path length can be controlled more precisely.
  • the plurality of movable guide rolls 8 included in the first chamber 4a and the second chamber 4b may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
  • the relative humidity in the second chamber 4b on the outlet 6 side is preferably larger than the relative humidity in the first chamber 4a on the inlet 5 side.
  • the PVA film 1 can be humidified more efficiently by passing the second chamber 4b having a higher relative humidity after passing the first chamber 4a having a lower relative humidity.
  • the humidifier 3 may be composed of three or more chambers (chambers) such as providing a third chamber between the first chamber 4a and the second chamber 4b shown in FIG.
  • the three or more chambers are preferably capable of independently adjusting the relative humidity in the room, and more preferably capable of adjusting the internal temperature together with the relative humidity in the room.
  • each chamber is provided with at least one movable guide roll 8 described above so that the transport path length of the PVA film 1 in each chamber can be freely changed.
  • each chamber has two or more movable guide rolls 8 because the change in the conveyance path length can be further increased and the conveyance path length can be more precisely controlled.
  • the plurality of movable guide rolls 8 included in three or more chambers may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
  • the step S10 for obtaining the humidified film is preferably a step S102 for detecting the moisture content of the humidified film 2 derived from the humidifier 3 with reference to FIG.
  • Process S102 and process S103 can be performed using the humidification system containing the humidification apparatus 3 mentioned above.
  • the humidifying system includes a humidifying unit including the humidifying device 3 described above, a detecting unit 10 that detects the moisture content of the humidifying film 2 derived from the humidifying device 3, and the detecting unit 10. And a control unit 20 that controls the position of the movable guide roll 8 based on the detection result of the detection unit 10.
  • Step S102 can be performed by the detection unit 10
  • step S103 can be performed by the control unit 20.
  • the method for producing the humidified film 2 including the series of steps S101 to S103 is advantageous for continuously and stably producing the humidified film 2 having a desired moisture content. That is, according to this method, based on the detection result obtained in the detecting step S102, the position of the movable guide roll 8 so that the moisture content of the humidifying film 2 becomes a desired value (or within a desired range), and thus the PVA film.
  • One conveyance path length can be feedback-controlled.
  • step S10 for obtaining a humidified film including a series of steps S101 to S103 is, for example, as follows.
  • the humidification film 2 in which the moisture content is adjusted is manufactured by adjusting the transport path length of the PVA film 1 in the humidifier 3 (step S101).
  • the moisture content of the humidified film 2 derived from the outlet 6 is detected by the detection unit 10 (step S102), and it is determined whether or not the moisture content detection value is within a desired value or a desired range. This determination may be performed by the detection unit 10 or may be performed by the control unit 20.
  • the control unit 20 maintains the position of the movable guide roll 8 without changing in step S103.
  • step S103 the control unit 20 adjusts the position of the movable guide roll 8 to change the transport path length of the PVA film 1 in the chamber 4. Specifically, the control unit 20 determines that the moisture content detection value is smaller than the desired value or the desired range so that the transport path length of the PVA film 1 becomes shorter when the moisture content detection value is larger than the desired value or the desired range. When it is small, the position of the movable guide roll 8 is adjusted so that the transport path length of the PVA film 1 becomes long.
  • the moisture content of the humidified film 2 is detected again by the detection unit 10, and whether or not the moisture content detection value is within a desired value or a desired range. Check. The above control is repeated until the moisture content detection value becomes a desired value or within a desired range.
  • the detection unit 10 detects the moisture content of the humidified film 2 continuously or continuously at certain time intervals, and in response thereto, the control unit 20 feedbacks the position of the movable guide roll 8. Control is performed continuously or continuously at certain time intervals.
  • the change amount of the transport path length of the PVA film 1 and the change amount of the moisture content of the humidified film 2 are calculated.
  • the correlation may be examined in advance, and the amount of change in the conveyance path length may be determined based on the correlation.
  • the humidifying device 3 includes a plurality of movable guide rolls 8
  • the amount of change in the transport path length of the PVA film 1 is a predetermined value for the movable guide rolls 8 to be moved, the number of the movable guide rolls 8, the moving distance of the individual movable guide rolls 8, and the like. It chooses suitably so that it may become.
  • the detection unit 10 is preferably capable of detecting the moisture content in-line while transporting the humidified film 2 derived from the humidifier 3, and as such, an infrared absorption moisture meter is preferably used. Can do.
  • the moisture content detected by the infrared absorption type moisture meter may be adopted as the moisture content detection value described above, or the correlation between the moisture content by the infrared absorption type moisture meter and the moisture content according to the dry weight method is shown.
  • a calibration curve may be prepared in advance, and the moisture content according to the dry weight method converted by this calibration curve may be adopted as the moisture content detection value.
  • the control unit 20 can be a computer that can receive a signal from the detection unit 10 and controls the position of the movable guide roll 8 based on the signal.
  • the film humidification system can include a heating device for heating the PVA film 1 disposed on the upstream side of the humidification device 3.
  • a heating device for heating the PVA film 1 disposed on the upstream side of the humidification device 3.
  • the above heating device is a heating chamber in which the internal temperature can be adjusted (such as a hot air oven that can increase the internal temperature by supplying hot air), one or more hot rolls, a heater (infrared heater, halogen heater, panel heater, etc.) And so on.
  • the heating temperature of the film 1 by the heating device is, for example, 50 to 150 ° C., preferably 60 to 130 ° C., more preferably 70 to 120 ° C.
  • the heating temperature of the PVA film 1 by the heating device is the internal temperature of the chamber 4 when the PVA film 1 is humidified.
  • the temperature of the PVA film 1 in the chamber 4 is preferably 10 ° C. or higher, more preferably 20 ° C. or higher.
  • the heat treatment of the PVA film 1 by the heating device is usually performed in a relative humidity environment lower than the relative humidity in the chamber 4.
  • the humidifier used in step S10 for obtaining the humidified film is not limited as long as it can change the transport path length of the PVA film in the humidifier, and the humidifier 3 having the movable guide roll 8 is not limited.
  • it has one or more guide rolls that define a transport path of the PVA film that can be moved into and out of the chamber where the relative humidity inside can be adjusted.
  • the guide path may be changed so that the transport path length of the PVA film in the chamber can be freely changed.
  • the moisture content of the obtained humidified film 2 depends on the thickness of the humidified film 2, it is preferably 4 to 15% by weight, more preferably 5 to 13% by weight, 7% by weight or more, and further 8% by weight. % Or more.
  • Step S20 for obtaining a stretched film is a step for obtaining a stretched film by dry-stretching the humidified film 2.
  • Dry stretching refers to stretching performed in the air, and is usually longitudinal uniaxial stretching.
  • a film is passed between a heated roll whose surface is heated and a guide roll (or a heated roll) having a different peripheral speed from the heated roll, and heating using a heated roll.
  • Hot roll stretching that performs longitudinal stretching below; Between rolls that perform longitudinal stretching due to the difference in peripheral speed between these two nip rolls while passing heating means (such as an oven) between two nip rolls installed at a distance. Stretching; tenter stretching; compression stretching and the like.
  • the stretching temperature (the surface temperature of the hot roll, the temperature in the oven, etc.) is, for example, 80 to 150 ° C., preferably 100 to 135 ° C.
  • the stretching ratio of the humidified film 2 is preferably 3.5 times or more, more preferably 4 times or more, from the viewpoint of optical properties (particularly polarization properties) of the polarizing film when the stretched film is used as a raw material for the polarizing film. It is.
  • the draw ratio is usually about 8 times or less.
  • the stretched film continuously obtained as a long film may be wound up once to be a film roll, or may be continuously supplied to the next step such as a polarizing film forming step without being wound up.
  • the stretched film obtained by the production method according to the present invention can be suitably used as a raw material for a polarizing film.
  • the polarizing film includes a step of adsorbing the dichroic dye by dyeing the stretched film with the dichroic dye; a step of crosslinking the film on which the dichroic dye is adsorbed; and a step of washing with water after the crosslinking treatment. It can be manufactured after that.
  • the dichroic dye iodine or a dichroic organic dye can be used.
  • a method of dyeing the stretched film with a dichroic dye for example, a method of immersing the stretched film in an aqueous solution (dye solution) containing the dichroic dye is employed.
  • the stretched film is preferably subjected to an immersion treatment (swelling treatment) in water before the dyeing treatment.
  • iodine When iodine is used as the dichroic dye, a method of dyeing a stretched film in an aqueous solution containing iodine and potassium iodide is usually employed.
  • the iodine content in this dyeing aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water.
  • the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water.
  • the temperature of the dyeing aqueous solution is usually about 20 to 40 ° C.
  • a method of dyeing a stretched film in a dyeing aqueous solution containing a water-soluble dichroic organic dye is usually employed.
  • the content of the dichroic organic dye in the aqueous dyeing solution is usually 1 ⁇ 10 ⁇ 4 to 10 parts by weight, preferably 1 ⁇ 10 ⁇ 3 to 1 part by weight per 100 parts by weight of water.
  • This dyeing aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid.
  • the temperature of the dyeing aqueous solution is usually about 20 to 80 ° C.
  • the crosslinking treatment after dyeing with a dichroic dye can be performed by immersing the dyed film in an aqueous solution containing a crosslinking agent.
  • a crosslinking agent is boric acid, but other cross-linking agents such as boron compounds such as borax, glyoxal, and glutaraldehyde can also be used. Only 1 type may be used for a crosslinking agent and it may use 2 or more types together.
  • the amount of the crosslinking agent in the aqueous solution containing the crosslinking agent is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water.
  • the aqueous solution containing a crosslinking agent preferably contains potassium iodide.
  • the amount of potassium iodide in the crosslinking agent-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water.
  • the temperature of the aqueous solution containing a crosslinking agent is usually 50 ° C. or higher, preferably 50 to 85 ° C.
  • the film after the crosslinking treatment is usually washed with water.
  • the water washing treatment can be performed, for example, by immersing the crosslinked polyvinyl alcohol resin film in water.
  • the temperature of water in the water washing treatment is usually about 1 to 40 ° C.
  • the film may be subjected to wet stretching as necessary.
  • a polarizing film is obtained by performing a drying treatment after washing with water.
  • the drying treatment can be drying with a hot air dryer, drying by contacting with a hot roll, drying with a far infrared heater, and the like.
  • the temperature for the drying treatment is usually about 30 to 100 ° C., preferably 50 to 90 ° C.
  • the thickness of the polarizing film is usually about 2 to 40 ⁇ m. From the viewpoint of thinning the polarizing plate, the thickness of the polarizing film is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less, and even more preferably 10 ⁇ m or less.
  • a polarizing plate can be obtained by bonding a thermoplastic resin film to one or both sides of a polarizing film via an adhesive layer.
  • the thermoplastic resin film is a film composed of a thermoplastic resin having translucency, preferably an optically transparent thermoplastic resin.
  • the thermoplastic resin constituting the thermoplastic resin film is, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like); triacetyl cellulose or diacetyl cellulose.
  • Cellulose resins such as: Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resins; (Meth) acrylic resins such as methyl methacrylate resins; Polystyrene resins; Polyvinyl chloride resins; Acrylonitrile Butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; Hong resins; poly (ether sulfone) resins; polyarylate resin; polyamideimide resin; may be a polyimide resin or the like.
  • chain polyolefin resin examples include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins. More specific examples include polypropylene resins (polypropylene resins that are homopolymers of propylene and copolymers mainly composed of propylene), polyethylene resins (polyethylene resins that are homopolymers of ethylene and ethylene mainly) A copolymer).
  • Cyclic polyolefin-based resin is a general term for resins that are polymerized using cyclic olefins as polymerization units.
  • Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof.
  • norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.
  • Cellulosic resins are those in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) are substituted with acetyl groups, propionyl groups and / or butyryl groups. Further, it refers to a cellulose organic acid ester or a cellulose mixed organic acid ester. For example, cellulose acetate, propionate, butyrate, and mixed esters thereof can be used. Among these, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferable.
  • the polyester-based resin is a resin other than the above cellulose-based resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol.
  • a polyvalent carboxylic acid or a derivative thereof a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate.
  • a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.
  • suitable polyester-based resins include polyethylene terephthalate.
  • Polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency.
  • the polycarbonate-based resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolymerized polycarbonate with improved wavelength dependency, or the like.
  • (Meth) acrylic resin is a polymer containing structural units derived from (meth) acrylic monomers.
  • the polymer is typically a polymer containing a methacrylic acid ester.
  • it is a polymer in which the proportion of structural units derived from methacrylic acid esters is 50% by weight or more based on the total structural units.
  • the (meth) acrylic resin may be a methacrylic acid ester homopolymer or a copolymer containing structural units derived from other polymerizable monomers.
  • the proportion of structural units derived from other polymerizable monomers is preferably 50% by weight or less based on the total structural units.
  • a methacrylic acid alkyl ester As the methacrylic acid ester that can constitute the (meth) acrylic resin, a methacrylic acid alkyl ester is preferable.
  • alkyl methacrylates include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate.
  • alkyl methacrylate having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl methacrylate.
  • the carbon number of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4.
  • methacrylic acid esters may be used alone or in combination of two or more.
  • Examples of the other polymerizable monomer that can constitute the (meth) acrylic resin include acrylic acid esters and other compounds having a polymerizable carbon-carbon double bond in the molecule. Other polymerizable monomers may be used alone or in combination of two or more.
  • an acrylic acid alkyl ester is preferable.
  • alkyl acrylate esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate.
  • alkyl acrylates having an alkyl group having 1 to 8 carbon atoms such as 2-hydroxyethyl acrylate.
  • the number of carbon atoms of the alkyl group contained in the alkyl acrylate is preferably 1 to 4.
  • acrylic acid esters may be used alone or in combination of two or more.
  • the compound having a polymerizable carbon-carbon double bond in the molecule examples include vinyl compounds such as ethylene, propylene and styrene, and vinylcyan compounds such as acrylonitrile.
  • vinyl compounds having a polymerizable carbon-carbon double bond in the molecule may be used alone or in combination of two or more.
  • the thermoplastic resin film can be a protective film for protecting the polarizing film.
  • the thermoplastic resin film can also be a protective film having an optical function such as a retardation film and a brightness enhancement film.
  • a retardation provided with an arbitrary retardation value by stretching (such as uniaxial stretching or biaxial stretching) a thermoplastic resin film made of the above materials or forming a liquid crystal layer or the like on the film. It can be a film.
  • the thermoplastic resin film may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or an antifouling layer, which is laminated on the surface.
  • the thickness of the thermoplastic resin film is usually 1 to 100 ⁇ m, but is preferably 5 to 60 ⁇ m and more preferably 5 to 50 ⁇ m from the viewpoints of strength, handleability, and thinning of the polarizing plate.
  • a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and preferably an aqueous adhesive, an active energy ray. It is a curable adhesive.
  • a water-based adhesive is one in which an adhesive component is dissolved in water or dispersed in water.
  • the aqueous adhesive preferably used is, for example, an adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component.
  • the polyvinyl alcohol-based resin can be a polyvinyl alcohol resin such as partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, or a carboxyl group-modified polyvinyl alcohol. Further, modified polyvinyl alcohol resins such as acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol may be used.
  • Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymerization of vinyl acetate and other monomers copolymerizable therewith. It may be a polyvinyl alcohol copolymer obtained by saponifying the coalescence.
  • An aqueous adhesive containing a polyvinyl alcohol resin as an adhesive component is usually an aqueous solution of a polyvinyl alcohol resin.
  • concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.
  • Adhesives composed of aqueous solutions of polyvinyl alcohol resins are used to improve adhesiveness, such as curable components such as polyhydric aldehydes, melamine compounds, zirconia compounds, zinc compounds, glyoxal, glyoxal derivatives, and water-soluble epoxy resins. It is preferable to contain a crosslinking agent.
  • water-soluble epoxy resins include polyamide polyamine epoxy resins obtained by reacting polychloroalkylenes such as diethylenetriamine and triethylenetetramine with polycarboxylic acid polyamines such as adipic acid and epichlorohydrin. Can be suitably used.
  • the addition amount of the curable component or the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesiveness tends to be small, and the addition amount is polyvinyl.
  • the adhesive layer tends to become brittle.
  • a urethane resin used as the main component of the adhesive
  • a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group can be given.
  • the polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced.
  • Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion.
  • the active energy ray-curable adhesive is an adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays.
  • active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays.
  • the adhesive layer of the polarizing plate is a cured product layer of the adhesive.
  • the active energy ray curable adhesive can be an adhesive containing an epoxy compound that is cured by cationic polymerization as a curable component, and preferably an ultraviolet curable adhesive containing such an epoxy compound as a curable component. It is an agent.
  • the epoxy compound here means a compound having an average of 1 or more, preferably 2 or more epoxy groups in the molecule.
  • the epoxy compound may be used alone or in combination of two or more.
  • the active energy ray-curable adhesive can contain a radically polymerizable (meth) acrylic compound as a curable component, instead of or together with the epoxy compound.
  • the (meth) acrylic compound is a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and at least two in the molecule.
  • (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having (meth) acryloyloxy groups.
  • the active energy ray-curable adhesive contains an epoxy compound that is cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator.
  • the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes.
  • the active energy ray-curable adhesive contains a radical polymerizable curable component such as a (meth) acrylic compound, it is preferable to contain a photo radical polymerization initiator.
  • photo radical polymerization initiator examples include acetophenone initiator, benzophenone initiator, benzoin ether initiator, thioxanthone initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like.
  • the bonding surface of the polarizing film and / or thermoplastic resin film Prior to bonding the thermoplastic resin film to the polarizing film, the bonding surface of the polarizing film and / or thermoplastic resin film is subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, and saponification treatment. Such surface activation treatment may be performed. By this surface activation treatment, the adhesion between the polarizing film and the thermoplastic resin film can be enhanced.
  • PVA film polyvinyl alcohol resin film
  • humidified film humidity-inducible film
  • 3 humidifier 4 chamber, 4a chamber 1st chamber, 4b chamber 2nd chamber, 5 inlet, 6 outlet, 7 non-movable guide rolls, 8 movable guide rolls, 10 detection units, 20 control units.

Abstract

Provided is a stretched film production method including: a step in which a long polyvinyl alcohol-based resin film is continuously guided into a humidifying device and a humidified film is obtained; and a step in which the humidified film discharged from the humidifying device is dry-stretched and a stretched film is obtained. The step in which the humidified film is obtained includes a step in which the water content of the humidified film is adjusted by changing the length of the path inside the humidification device along which the polyvinyl alcohol-based resin film is conveyed.

Description

延伸フィルムの製造方法Method for producing stretched film
　本発明は、長尺のポリビニルアルコール系樹脂フィルムから延伸フィルムを製造する方法に関する。 The present invention relates to a method for producing a stretched film from a long polyvinyl alcohol-based resin film.
　偏光板は、液晶表示装置等の画像表示装置における偏光素子などとして広く用いられている。偏光板としては、偏光フィルムの片面又は両面に接着剤等を用いて透明樹脂フィルム（保護フィルム等）を貼合した構成のものが一般的である。 The polarizing plate is widely used as a polarizing element in an image display device such as a liquid crystal display device. As a polarizing plate, the thing of the structure which bonded the transparent resin film (protective film etc.) on the single side | surface or both surfaces of the polarizing film using the adhesive agent etc. is common.
　偏光フィルムは主に、ポリビニルアルコール系樹脂からなる原反フィルムに対して、ヨウ素等の二色性色素を含有する染色浴に浸漬させる処理、次いでホウ酸等の架橋剤を含有する架橋浴に浸漬させる処理などを施すとともに、いずれかの段階でフィルムを一軸延伸することによって製造されている。一軸延伸には、上記浸漬処理の前に空中で延伸を行う乾式延伸と、上記染色浴及び架橋浴等の液中で延伸を行う湿式延伸とがある。 The polarizing film is mainly immersed in a dye bath containing a dichroic dye such as iodine, and then immersed in a cross-linking bath containing a cross-linking agent such as boric acid, with respect to the raw film made of polyvinyl alcohol resin. The film is produced by uniaxially stretching the film at any stage. Uniaxial stretching includes dry stretching in which stretching is performed in the air before the immersion treatment and wet stretching in which stretching is performed in a liquid such as the dyeing bath and the crosslinking bath.
　乾式延伸に供されるポリビニルアルコール系樹脂フィルムは、延伸適性を高めるために、フィルムの水分率を調整しておくことがある。例えば特開２００２－３３３５２１号公報（特許文献１）には、乾式延伸に供されるポリビニルアルコール系樹脂フィルムの含水率を乾燥によって１０％以下にすることが記載されている（段落［００１６］）。 The polyvinyl alcohol-based resin film used for dry stretching may be adjusted in moisture content in order to improve stretchability. For example, Japanese Patent Application Laid-Open No. 2002-333521 (Patent Document 1) describes that the moisture content of a polyvinyl alcohol-based resin film subjected to dry stretching is 10% or less by drying (paragraph [0016]). .
　フィルムの水分率調整に関し、例えば特開２００４－１６０８４６号公報（特許文献２）には、ポリビニルアルコール系フィルムを流延製膜により製造し、次いで、調湿機内にてフィルムの両面から水蒸気を吹き付ける調湿（加湿）処理を行うことが記載されている（段落［００５７］）。 Regarding the adjustment of the moisture content of a film, for example, in Japanese Patent Application Laid-Open No. 2004-16084 (Patent Document 2), a polyvinyl alcohol film is manufactured by casting, and then water vapor is sprayed from both sides of the film in a humidity controller. It describes that a humidity control (humidification) treatment is performed (paragraph [0057]).
特開２００２－３３３５２１号公報JP 2002-333521 A 特開２００４－１６０８４６号公報JP 2004-160846 A
　本発明の目的は、新たな方法で水分率が調整されたポリビニルアルコール系樹脂フィルムを用いて延伸フィルムを製造する方法を提供することにある。 An object of the present invention is to provide a method for producing a stretched film using a polyvinyl alcohol-based resin film whose moisture content is adjusted by a new method.
　本発明は、以下に示す延伸フィルムの製造方法を提供する。
　［１］　長尺のポリビニルアルコール系樹脂フィルムを連続的に加湿装置に導入して、加湿フィルムを得る工程と、
　前記加湿装置から導出された前記加湿フィルムを乾式延伸して、延伸フィルムを得る工程と、
を含み、
　前記加湿フィルムを得る工程は、前記加湿装置内での前記ポリビニルアルコール系樹脂フィルムの搬送経路長を変化させることによって前記加湿フィルムの水分率を調整する工程を含む、延伸フィルムの製造方法。 This invention provides the manufacturing method of the stretched film shown below.
[1] A step of continuously introducing a long polyvinyl alcohol resin film into a humidifier to obtain a humidified film;
Dry-stretching the humidified film derived from the humidifier to obtain a stretched film;
Including
The step of obtaining the humidified film includes a step of adjusting a moisture content of the humidified film by changing a transport path length of the polyvinyl alcohol resin film in the humidifier.
　［２］　前記加湿装置は、内部の相対湿度を調整可能なチャンバと、前記チャンバ内に配置され、前記ポリビニルアルコール系樹脂フィルムの搬送経路を規定する複数のガイドロールと、を備えており、
　前記複数のガイドロールの少なくとも１つは、位置移動が可能な可動ガイドロールであり、
　前記水分率を調整する工程は、前記可動ガイドロールの位置を調整することを含む、［１］に記載の製造方法。 [2] The humidifier includes a chamber capable of adjusting an internal relative humidity, and a plurality of guide rolls that are disposed in the chamber and define a conveyance path of the polyvinyl alcohol-based resin film,
At least one of the plurality of guide rolls is a movable guide roll capable of moving the position,
The process according to [1], wherein the step of adjusting the moisture content includes adjusting a position of the movable guide roll.
　［３］　前記加湿フィルムを得る工程は、
　前記加湿装置から導出された前記加湿フィルムの水分率を検出する工程と、
　前記検出する工程で得られる検出結果に基づいて、前記可動ガイドロールの位置を制御する工程と、
をさらに含む、［２］に記載の製造方法。 [3] The step of obtaining the humidified film includes
Detecting the moisture content of the humidified film derived from the humidifier;
A step of controlling the position of the movable guide roll based on the detection result obtained in the detecting step;
The production method according to [2], further comprising:
　［４］　前記水分率を検出する工程において前記水分率は、前記加湿装置から導出された前記加湿フィルムを搬送しながらインラインで検出する、［３］に記載の製造方法。 [4] The manufacturing method according to [3], wherein in the step of detecting the moisture content, the moisture content is detected in-line while conveying the humidified film derived from the humidifier.
　［５］　前記可動ガイドロールは、水平方向から傾いた方向へ平行移動可能である、［２］～［４］のいずれかに記載の製造方法。 [5] The manufacturing method according to any one of [2] to [4], wherein the movable guide roll is movable in a direction inclined from a horizontal direction.
　［６］　前記チャンバは、前記ポリビニルアルコール系樹脂フィルムが導入される側の第１室と、前記加湿フィルムを導出する側の第２室と、を含み、
　前記第２室内の相対湿度は、前記第１室内の相対湿度よりも高い、［２］～［５］のいずれかに記載の製造方法。 [6] The chamber includes a first chamber on a side where the polyvinyl alcohol-based resin film is introduced, and a second chamber on a side where the humidified film is led out.
The manufacturing method according to any one of [2] to [5], wherein the relative humidity in the second room is higher than the relative humidity in the first room.
　［７］　前記第１室及び前記第２室のそれぞれが前記可動ガイドロールを備える、［６］に記載の製造方法。 [7] The manufacturing method according to [6], wherein each of the first chamber and the second chamber includes the movable guide roll.
　本発明によれば、新たな方法で水分率が調整されたポリビニルアルコール系樹脂フィルムを用いて延伸フィルムを製造する方法を提供することができる。 According to the present invention, it is possible to provide a method for producing a stretched film using a polyvinyl alcohol-based resin film whose moisture content is adjusted by a new method.
本発明に係る延伸フィルムの製造方法の一例を示すフローチャートである。It is a flowchart which shows an example of the manufacturing method of the stretched film which concerns on this invention. 加湿フィルムを得る工程Ｓ１０で好適に用いられる加湿装置及びこれを含む加湿システムの一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the humidification apparatus used suitably by process S10 which obtains a humidification film, and a humidification system containing the same. 可動ガイドロールの位置移動方向の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the position moving direction of a movable guide roll. 加湿フィルムを得る工程Ｓ１０で好適に用いられる加湿装置及びこれを含む加湿システムの他の一例を示す概略断面図である。It is a schematic sectional drawing which shows another example of the humidification apparatus suitably used by process S10 which obtains a humidification film, and a humidification system containing this.
　＜延伸フィルムの製造方法＞
　図１を参照して、本発明に係る延伸フィルムの製造方法は、
　長尺のポリビニルアルコール系樹脂フィルム（以下、ＰＶＡフィルムともいう。）を連続的に加湿装置に導入して、加湿フィルムを得る工程Ｓ１０と、
　加湿装置から導出された前記加湿フィルムを乾式延伸して、延伸フィルムを得る工程Ｓ２０と、
を含む。 <Method for producing stretched film>
With reference to FIG. 1, the manufacturing method of the stretched film which concerns on this invention is the following.
A step S10 of continuously introducing a long polyvinyl alcohol-based resin film (hereinafter also referred to as a PVA film) into a humidifier to obtain a humidified film;
Step S20 for dry stretching the humidified film derived from the humidifier to obtain a stretched film;
including.
　（１）加湿フィルムを得る工程Ｓ１０
　加湿フィルムを得る工程Ｓ１０は、長尺のＰＶＡフィルムを連続的に加湿装置に導入することによって加湿フィルムを得る工程であり、図１を参照して、当該加湿装置内でのＰＶＡフィルムの搬送経路長を変化させることによって加湿フィルムの水分率を調整する工程Ｓ１０１を含む。 (1) Step S10 for obtaining a humidified film
Step S10 for obtaining a humidified film is a step for obtaining a humidified film by continuously introducing a long PVA film into the humidifier, and referring to FIG. 1, the transport path of the PVA film in the humidifier Step S101 for adjusting the moisture content of the humidified film by changing the length is included.
　（１－１）ポリビニルアルコール系樹脂フィルム
　ＰＶＡフィルムを構成するポリビニルアルコール系樹脂としては、ポリ酢酸ビニル系樹脂をケン化したものを用いることができる。ポリ酢酸ビニル系樹脂としては、酢酸ビニルの単独重合体であるポリ酢酸ビニルのほか、酢酸ビニルとこれに共重合可能な他の単量体との共重合体が例示される。酢酸ビニルに共重合可能な他の単量体としては、例えば、不飽和カルボン酸類、オレフィン類、ビニルエーテル類、不飽和スルホン酸類、アンモニウム基を有する（メタ）アクリルアミド類等が挙げられる。なお、「（メタ）アクリル」とは、アクリル及びメタクリルよりなる群から選ばれる少なくとも１種を表す。その他の「（メタ）」を付した用語においても同様である。 (1-1) Polyvinyl alcohol-based resin film As the polyvinyl alcohol-based resin constituting the PVA film, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group. “(Meth) acryl” represents at least one selected from the group consisting of acryl and methacryl. The same applies to other terms with “(meta)”.
　ポリビニルアルコール系樹脂のケン化度は、８０．０～１００．０モル％の範囲であることができるが、好ましくは９０．０～１００．０モル％の範囲であり、より好ましくは９８．０～１００．０モル％の範囲である。ケン化度が８０．０モル％未満であると、得られる延伸フィルムを偏光フィルムの原料として使用する場合、当該偏光フィルムを含む偏光板の耐水性及び耐湿熱性が低下し得る。 The degree of saponification of the polyvinyl alcohol-based resin can be in the range of 80.0 to 100.0 mol%, preferably in the range of 90.0 to 100.0 mol%, more preferably 98.0. It is in the range of ˜100.0 mol%. When the saponification degree is less than 80.0 mol%, when the obtained stretched film is used as a raw material for the polarizing film, the water resistance and wet heat resistance of the polarizing plate including the polarizing film can be lowered.
　ケン化度とは、ポリビニルアルコール系樹脂の原料であるポリ酢酸ビニル系樹脂に含まれる酢酸基（アセトキシ基：－ＯＣＯＣＨ3）がケン化工程により水酸基に変化した割合をユニット比（モル％）で表したものであり、下記式：
　ケン化度（モル％）＝１００×（水酸基の数）／（水酸基の数＋酢酸基の数）
で定義される。ケン化度は、ＪＩＳ　Ｋ　６７２６（１９９４）に準拠して求めることができる。ケン化度が高いほど、水酸基の割合が高いことを示しており、従って結晶化を阻害する酢酸基の割合が低いことを示している。 The degree of saponification is the unit ratio (mol%) of the ratio of acetate groups (acetoxy groups: —OCOCH 3 ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, to hydroxyl groups by the saponification process. The following formula:
Degree of saponification (mol%) = 100 × (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups)
Defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.
　ポリビニルアルコール系樹脂の平均重合度は、好ましくは１００～１００００であり、より好ましくは１５００～８０００であり、さらに好ましくは２０００～５０００である。ポリビニルアルコール系樹脂の平均重合度もＪＩＳ　Ｋ　６７２６（１９９４）に準拠して求めることができる。平均重合度が１００未満では、得られる延伸フィルムを偏光フィルムの原料として使用する場合、好ましい偏光性能を有する偏光フィルムを得ることが困難であり、１００００超では溶媒への溶解性が悪化し、ＰＶＡフィルムの形成が困難となり得る。 The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and further preferably 2000 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can also be determined according to JIS K 6726 (1994). When the average degree of polymerization is less than 100, when the obtained stretched film is used as a raw material for the polarizing film, it is difficult to obtain a polarizing film having a preferable polarizing performance, and when it exceeds 10,000, the solubility in a solvent deteriorates. Film formation can be difficult.
　ＰＶＡフィルムは、上述したポリビニルアルコール系樹脂を製膜したものである。製膜方法は、特に限定されるものではなく、溶融押出法、溶剤キャスト法のような公知の方法を採用することができる。ＰＶＡフィルムの厚みは、例えば１０～１５０μｍ程度であり、好ましくは１００μｍ以下、より好ましくは６５μｍ以下、さらに好ましくは５０μｍ以下、特に好ましくは３５μｍ以下（例えば３０μｍ以下、さらには２０μｍ以下）である。 The PVA film is obtained by forming the polyvinyl alcohol resin described above. The film forming method is not particularly limited, and a known method such as a melt extrusion method or a solvent casting method can be employed. The thickness of the PVA film is, for example, about 10 to 150 μm, preferably 100 μm or less, more preferably 65 μm or less, still more preferably 50 μm or less, and particularly preferably 35 μm or less (for example, 30 μm or less, further 20 μm or less).
　ＰＶＡフィルムは、可塑剤等の添加剤を含有することができる。可塑剤の好ましい例は多価アルコールであり、その具体例は、エチレングリコール、グリセリン、プロピレングリコール、ジエチレングリコール、ジグリセリン、トリエチレングリコール、トリグリセリン、テトラエチレングリコール、トリメチロールプロパン、ポリエチレングリコール等を含む。ＰＶＡフィルムは、１種又は２種以上の可塑剤を含有することができる。可塑剤の含有量は、ＰＶＡフィルムを構成するポリビニルアルコール系樹脂１００重量部に対して、通常５～２０重量部であり、好ましくは７～１５重量部である。 The PVA film can contain additives such as a plasticizer. Preferred examples of the plasticizer are polyhydric alcohols, and specific examples thereof include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, triglycerin, tetraethylene glycol, trimethylolpropane, polyethylene glycol and the like. . The PVA film can contain one or more plasticizers. The content of the plasticizer is usually 5 to 20 parts by weight, preferably 7 to 15 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin constituting the PVA film.
　（１－２）加湿装置
　図２に、加湿フィルムを得る工程Ｓ１０で好適に用いられる加湿装置及びこれを含む加湿システムの一例を概略断面図で示している。図２に示される加湿装置３は、長尺のＰＶＡフィルム１を連続的に加湿する（水分率を上昇させる）ための装置であり、内部の相対湿度を調整可能なチャンバ４を含む。チャンバ４は、加湿される対象である長尺のＰＶＡフィルム１をチャンバ４内に導入するための導入口５と、加湿されたフィルム（加湿フィルム）２をチャンバ４から導出するための導出口６とを有する。 (1-2) Humidifier FIG. 2 is a schematic cross-sectional view showing an example of a humidifier suitably used in step S10 for obtaining a humidified film and a humidifying system including the humidifier. The humidifying device 3 shown in FIG. 2 is a device for continuously humidifying the long PVA film 1 (increasing the moisture content), and includes a chamber 4 capable of adjusting the internal relative humidity. The chamber 4 has an introduction port 5 for introducing the long PVA film 1 to be humidified into the chamber 4 and an outlet port 6 for deriving the humidified film (humidified film) 2 from the chamber 4. And have.
　チャンバ４内には複数のガイドロール７，８が配置されている。これらのガイドロール７，８は、チャンバ４内のＰＶＡフィルム１を案内するロールであり、チャンバ４内でのＰＶＡフィルム１の搬送経路を規定する。加湿環境下にあるチャンバ４内に導入口５から連続的に導入されたＰＶＡフィルム１は、当該搬送経路に沿って（各ガイドロール７，８の外周に巻き掛けられた状態で）連続的に搬送される。この搬送過程でＰＶＡフィルム１は、ある滞留時間、加湿環境下にあるチャンバ４内に置かれることによって加湿される。加湿されたフィルム２は、連続的に導出口６から導出され、次の延伸フィルムを得る工程Ｓ２０に供される。あるいは、導出口６から導出された加湿フィルム２を一旦ロール状に巻き取り、後にこのフィルムロールから加湿フィルム２を巻き出して延伸フィルムを得る工程Ｓ２０に供してもよい。好ましくは、加湿フィルム２は、一旦巻き取られることなく、引き続き延伸フィルムを得る工程Ｓ２０に供される。 A plurality of guide rolls 7 and 8 are arranged in the chamber 4. These guide rolls 7 and 8 are rolls for guiding the PVA film 1 in the chamber 4, and define a conveyance path of the PVA film 1 in the chamber 4. The PVA film 1 continuously introduced into the chamber 4 in the humidified environment from the introduction port 5 is continuously along the conveyance path (in a state of being wound around the outer periphery of the guide rolls 7 and 8). Be transported. In this conveyance process, the PVA film 1 is humidified by being placed in a chamber 4 in a humidified environment for a certain residence time. The humidified film 2 is continuously led out from the outlet 6 and subjected to step S20 to obtain the next stretched film. Alternatively, the humidified film 2 led out from the outlet 6 may be temporarily wound into a roll shape, and then the humidified film 2 may be unwound from the film roll to be subjected to step S20 to obtain a stretched film. Preferably, the humidified film 2 is subjected to step S20 to obtain a stretched film without being wound once.
　加湿装置３において、チャンバ４内に設置されるガイドロール群は、位置移動が可能である可動ガイドロール８（図２の例において２個）と、位置移動が可能でない非可動ガイドロール７（図２の例において３個）で構成されている。「位置移動が可能である可動ガイドロール」とは、ガイドロールの回転軸のチャンバ４内における配置位置を移動させることができるガイドロールをいう。非可動ガイドロール７及び可動ガイドロール８は、それぞれ独立して、駆動ロールであってもよいし、フリーロールであってもよい。駆動ロールとは、それに接触するフィルムに対してフィルム搬送のための駆動力を与えることができるロールをいい、モータ等のロール駆動源が直接又は間接的に接続されたロールや、サクションロール（吸引ロール）等が挙げられる。フリーロールとは、単に走行するフィルムを支持する役割を担い、フィルム搬送のための駆動力を与えることができないロールをいう。 In the humidifier 3, the guide roll group installed in the chamber 4 includes a movable guide roll 8 (two in the example of FIG. 2) whose position can be moved, and a non-movable guide roll 7 (FIG. 3 in the example of 2). The “movable guide roll capable of position movement” refers to a guide roll that can move the position of the rotation axis of the guide roll in the chamber 4. The non-movable guide roll 7 and the movable guide roll 8 may be independently a drive roll or a free roll. The driving roll is a roll that can give a driving force for film conveyance to a film that contacts the roll. A roll in which a roll driving source such as a motor is connected directly or indirectly, a suction roll (suction) Roll). The free roll is a roll that simply plays a role of supporting a traveling film and cannot give a driving force for film conveyance.
　可動ガイドロール８を有する加湿装置３によれば、可動ガイドロール８の位置調整によって加湿装置３（チャンバ４）内でのＰＶＡフィルム１の搬送経路長を自在に変化させることができる。ＰＶＡフィルム１の搬送経路長の変化は、加湿装置３（チャンバ４）内での滞留時間の変化を意味している。従って、可動ガイドロール８の位置調整によって、得られる加湿フィルム２の加湿状態（水分率）を制御することができる。すなわち、加湿装置３を用いる場合において、加湿フィルム２の水分率を調整する工程Ｓ１０１は、加湿装置３が有する少なくとも１つの可動ガイドロール８の位置を調整することを含む。 According to the humidifier 3 having the movable guide roll 8, the transport path length of the PVA film 1 in the humidifier 3 (chamber 4) can be freely changed by adjusting the position of the movable guide roll 8. The change of the conveyance path length of the PVA film 1 means the change of the residence time in the humidifier 3 (chamber 4). Therefore, the humidified state (moisture ratio) of the obtained humidified film 2 can be controlled by adjusting the position of the movable guide roll 8. That is, in the case of using the humidifying device 3, the step S <b> 101 for adjusting the moisture content of the humidifying film 2 includes adjusting the position of at least one movable guide roll 8 included in the humidifying device 3.
　従来のフィルム加湿装置においては一般的に、上記特許文献２のように、加湿装置内の加湿環境を制御することによって、得られる加湿フィルムの加湿状態（水分率）を調整していた。しかし、加湿装置内の加湿環境の制御によって加湿フィルムの加湿状態を精密に調整することは容易ではないし、加湿装置内の加湿環境を所望の環境へ調整するにはある程度の時間を要するため、所望の加湿状態（水分率）を有する加湿フィルムを得るまでに多くのフィルムロスが生じるという問題もあった。本発明で好適に用いられる加湿装置３によれば、チャンバ４内におけるＰＶＡフィルム１の搬送経路長、従って滞留時間を短時間で変化させることができるため、仮に加湿フィルム２の加湿状態（水分率）が所望の状態になっていない場合や、所望の加湿状態（水分率）を変化させる場合などにおいても、短時間で所望の加湿状態（水分率）を有する加湿フィルム２を提供することができる。また、可動ガイドロール８の位置移動によって搬送経路長を変化させる加湿装置３によれば、搬送経路長、従って滞留時間を緻密に制御することができるため、加湿フィルム２の加湿状態（水分率）を精密に調整することができる。水分率の精密な調整は、延伸フィルムを得る工程Ｓ２０におけるＰＶＡフィルム１の延伸適性（とりわけ乾式延伸への適性）を向上させ得る。 Conventional film humidifiers generally adjust the humidified state (moisture ratio) of the obtained humidified film by controlling the humidification environment in the humidifier, as described in Patent Document 2 above. However, it is not easy to precisely adjust the humidified state of the humidified film by controlling the humidifying environment in the humidifier, and it takes some time to adjust the humidified environment in the humidifier to the desired environment. There was also a problem that many film losses occurred before obtaining a humidified film having a humidified state (moisture content). According to the humidifying device 3 preferably used in the present invention, since the transport path length of the PVA film 1 in the chamber 4 and thus the residence time can be changed in a short time, the humidified state of the humidified film 2 (water content) ) Is not in the desired state, or when the desired humidification state (water content) is changed, the humidified film 2 having the desired humidification state (water content) can be provided in a short time. . Further, according to the humidifying device 3 that changes the transport path length by moving the position of the movable guide roll 8, the transport path length and accordingly the residence time can be precisely controlled. Can be adjusted precisely. The precise adjustment of the moisture content can improve the stretchability (especially the suitability for dry stretching) of the PVA film 1 in step S20 for obtaining a stretched film.
　加湿装置３が備える非可動ガイドロール７及び可動ガイドロール８の数は図２の例に限定されず、可動ガイドロール８を少なくとも１つ備えていればよい。加湿装置３が備えるガイドロールのすべてが可動ガイドロール８であってもよい。搬送経路長の変化（最大搬送経路長と最小搬送経路長との差）をより大きくできる点、及び搬送経路長をより緻密に制御できる点から、加湿装置３は可動ガイドロール８を２以上有していることが好ましい。 The number of the non-movable guide rolls 7 and the movable guide rolls 8 included in the humidifying device 3 is not limited to the example of FIG. All of the guide rolls provided in the humidifying device 3 may be the movable guide rolls 8. The humidifier 3 has two or more movable guide rolls 8 because the change in the transport path length (difference between the maximum transport path length and the minimum transport path length) can be increased and the transport path length can be more precisely controlled. It is preferable.
　可動ガイドロール８の位置移動は、例えばボールネジ、油圧シリンダー、空気圧シリンダー、水圧シリンダー、電動シリンダー、リニアアクチュエーター等のような機構を用いて行うことができる。 The position of the movable guide roll 8 can be moved using a mechanism such as a ball screw, a hydraulic cylinder, a pneumatic cylinder, a hydraulic cylinder, an electric cylinder, or a linear actuator.
　可動ガイドロール８の位置移動は、例えば図２に示されるように、ＰＶＡフィルム１の搬送経路長を変化させることができるような位置移動であり、これは通常、可動ガイドロール８の平行移動を含む。平行移動とは、位置移動前後の可動ガイドロール８の回転軸が平行であることをいう。可動ガイドロール８の位置移動の方向は特に制限されず、例えば水平方向を基準とするとき、図３に示されるように水平方向と平行であってもよいし、図２に示されるように水平方向から傾いた方向であってもよい。加湿装置３が可動ガイドロール８を２以上有する場合において、これらの可動ガイドロール８は、同じ方向に移動可能であってもよいし、異なる方向に移動可能であってもよい。また、これらの可動ガイドロール８の可動距離も同じであってもよいし、異なっていてもよい。 The position movement of the movable guide roll 8 is a position movement that can change the transport path length of the PVA film 1 as shown in FIG. 2, for example. Including. The parallel movement means that the rotation axis of the movable guide roll 8 before and after the position movement is parallel. The direction of movement of the movable guide roll 8 is not particularly limited. For example, when the horizontal direction is used as a reference, it may be parallel to the horizontal direction as shown in FIG. 3 or horizontal as shown in FIG. The direction may be inclined from the direction. When the humidifying device 3 has two or more movable guide rolls 8, these movable guide rolls 8 may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
　可動ガイドロール８の位置移動方向が水平方向から傾いた方向であることは、加湿装置３の占有面積（設置床面積）を低減させるうえで有利である。水平方向から傾いた方向の好適な一例は、鉛直方向である。すなわちこの場合、可動ガイドロール８は、上下方向（縦方向）に昇降可能なロールである。例えば、加湿されるＰＶＡフィルム１のチャンバ４内への導入においてＰＶＡフィルム１の搬送方向は水平方向であることができ、加湿フィルム２のチャンバ４からの導出において加湿フィルム２の搬送方向も水平方向であることができるが（ただし、これに限定されるものではない。）、この場合、鉛直方向はＰＶＡフィルム１又は加湿フィルム２の搬送方向に対して垂直な方向である。 It is advantageous to reduce the occupied area (installed floor area) of the humidifier 3 that the moving direction of the movable guide roll 8 is inclined from the horizontal direction. A preferred example of the direction inclined from the horizontal direction is the vertical direction. That is, in this case, the movable guide roll 8 is a roll that can be raised and lowered in the vertical direction (vertical direction). For example, in the introduction of the PVA film 1 to be humidified into the chamber 4, the transport direction of the PVA film 1 can be horizontal, and in the lead-out of the humidified film 2 from the chamber 4, the transport direction of the humidified film 2 is also horizontal. However, in this case, the vertical direction is a direction perpendicular to the transport direction of the PVA film 1 or the humidified film 2.
　チャンバ４は、内部の水分調整によって内部の相対湿度を調整可能なものである。長尺のＰＶＡフィルム１を連続的にチャンバ４に通すことによりＰＶＡフィルム１の加湿（水分率の上昇）を連続的に行うことができる。チャンバ４内の相対湿度は、所望する加湿フィルム２の加湿状態（水分率）に応じて設定することができる。チャンバ４内の相対湿度は、例えば２０％以上であり、好ましくは３０％以上であり、さらには４０％以上であってもよい。 The chamber 4 can adjust the internal relative humidity by adjusting the internal moisture. By continuously passing the long PVA film 1 through the chamber 4, the PVA film 1 can be continuously humidified (increase in the moisture content). The relative humidity in the chamber 4 can be set according to the desired humidified state (moisture ratio) of the humidified film 2. The relative humidity in the chamber 4 is, for example, 20% or more, preferably 30% or more, and may be 40% or more.
　上記相対湿度は、通常９９％以下であり、好ましくは９５％以下である。相対湿度があまりに高いと、ＰＶＡフィルム１の温度によってはＰＶＡフィルム１の表面に結露を生じる場合がある。ＰＶＡフィルム１の表面に結露が発生すると、水の蒸発潜熱により、その結露部分においてＰＶＡフィルム１の温度が所望値まで上がらず、その結果、その結露部分において所望の加湿状態（水分率）とならないことがある。また、ＰＶＡフィルム１の表面に結露が生じると、後で結露跡が生じて加湿フィルム２、ひいては延伸フィルムや偏光フィルムの外観品質に悪影響を及ぼすことがある。結露跡とは、結露が生じ、それが乾燥した後に残る乾燥跡をいう。 The relative humidity is usually 99% or less, preferably 95% or less. If the relative humidity is too high, condensation may occur on the surface of the PVA film 1 depending on the temperature of the PVA film 1. When condensation occurs on the surface of the PVA film 1, the temperature of the PVA film 1 does not rise to a desired value in the condensation portion due to the latent heat of evaporation of water, and as a result, the desired humidified state (moisture ratio) does not occur in the condensation portion. Sometimes. Moreover, when dew condensation occurs on the surface of the PVA film 1, dew marks are generated later, which may adversely affect the appearance quality of the humidified film 2, and thus the stretched film and the polarizing film. Condensation traces are dry traces that remain after condensation has formed and dried.
　チャンバ４は、好ましくは、内部の相対湿度とともに内部温度を調整可能なものである。ＰＶＡフィルム１の温度を適度に高めることにより、ＰＶＡフィルム１の加湿を効率的に行うことができる。内部温度は、熱風の供給等により高めることができる。ＰＶＡフィルム１の温度調整のために、熱風の代わりに、又はこれと組み合わせて、赤外線ヒーター、ハロゲンヒーター、パネルヒーター等を用いたり、ガイドロール７，８の少なくとも１つとして熱ロールを用いたりすることもできる。ここでいう熱ロールとは、熱源（例えば、温水等の熱媒や赤外線ヒーター）を内部に備え、表面温度を高めることができるロールをいう。 The chamber 4 is preferably capable of adjusting the internal temperature together with the internal relative humidity. By appropriately increasing the temperature of the PVA film 1, the PVA film 1 can be efficiently humidified. The internal temperature can be increased by supplying hot air or the like. In order to adjust the temperature of the PVA film 1, an infrared heater, a halogen heater, a panel heater, or the like is used instead of or in combination with hot air, or a hot roll is used as at least one of the guide rolls 7 and 8. You can also. The term “heat roll” as used herein refers to a roll provided with a heat source (for example, a heat medium such as warm water or an infrared heater) to increase the surface temperature.
　ＰＶＡフィルム１を加湿処理する際のチャンバ４の内部温度、及びＰＶＡフィルム１の温度は、通常３５℃以上であり、好ましくは４０℃以上であり、より好ましくは４５℃以上である。内部温度及びＰＶＡフィルム１の温度が３５℃以上であることにより、加湿処理の効率を高めることができる。一方、内部温度及びＰＶＡフィルム１の温度があまりに高いとＰＶＡフィルム１の熱劣化を招き得ることから、チャンバ４の内部温度及びＰＶＡフィルム１の温度は、１５０℃以下であることが好ましく、１３０℃以下であることがより好ましく、１００℃以下であることがさらに好ましく、９０℃以下であることが特に好ましい。 The internal temperature of the chamber 4 when the PVA film 1 is humidified and the temperature of the PVA film 1 are usually 35 ° C. or higher, preferably 40 ° C. or higher, more preferably 45 ° C. or higher. When the internal temperature and the temperature of the PVA film 1 are 35 ° C. or higher, the efficiency of the humidification treatment can be increased. On the other hand, if the internal temperature and the temperature of the PVA film 1 are too high, the PVA film 1 may be thermally deteriorated. Therefore, the internal temperature of the chamber 4 and the temperature of the PVA film 1 are preferably 150 ° C. or less, and 130 ° C. More preferably, it is 100 degrees C or less, It is more preferable that it is 90 degrees C or less.
　チャンバ４内でのＰＶＡフィルム１の滞留時間は、所望する加湿フィルム２の加湿状態（水分率）に応じて、可動ガイドロール８の位置調整によって制御することができる。ＰＶＡフィルム１の滞留時間は、例えば５～５００秒程度である。 The residence time of the PVA film 1 in the chamber 4 can be controlled by adjusting the position of the movable guide roll 8 according to the humidified state (moisture content) of the humidified film 2 desired. The residence time of the PVA film 1 is, for example, about 5 to 500 seconds.
　図４は、加湿フィルムを得る工程Ｓ１０で好適に用いられる加湿装置及びこれを含む加湿システムの他の一例を示す概略断面図である。図４に示される加湿装置３は、複数の室からなるチャンバを含むこと以外は図２に示される加湿装置３と同様の構成を有する。具体的には、図４に示される加湿装置３においてチャンバは、ＰＶＡフィルム１の導入口５を含む第１室４ａと、加湿フィルム２の導出口６を含む第２室４ｂとで構成されている。第１室４ａと第２室４ｂとは、それぞれ独立して室内の相対湿度を調整可能なものであり、好ましくは室内の相対湿度とともに内部温度を調整可能なものである。 FIG. 4 is a schematic cross-sectional view showing another example of a humidifier and a humidifying system including the humidifier suitably used in step S10 for obtaining a humidified film. The humidifying device 3 shown in FIG. 4 has the same configuration as the humidifying device 3 shown in FIG. 2 except that it includes a chamber composed of a plurality of chambers. Specifically, in the humidifying device 3 shown in FIG. 4, the chamber is composed of a first chamber 4 a including the inlet 5 for the PVA film 1 and a second chamber 4 b including the outlet 6 for the humidified film 2. Yes. The first chamber 4a and the second chamber 4b are capable of independently adjusting the indoor relative humidity, and are preferably capable of adjusting the internal temperature together with the indoor relative humidity.
　各室内でのＰＶＡフィルム１の搬送経路長を自在に変化させることができるよう、第１室４ａと第２室４ｂとはそれぞれ、上述の可動ガイドロール８を少なくとも１つ備えることが好ましい。第１室４ａが備えるガイドロールのすべてが可動ガイドロール８であってもよく、第２室４ｂが備えるガイドロールのすべてが可動ガイドロール８であってもよい。搬送経路長の変化をより大きくできる点、及び搬送経路長をより緻密に制御できる点から、第１室４ａと第２室４ｂとはそれぞれ、可動ガイドロール８を２以上有していることが好ましい。第１室４ａ及び第２室４ｂに含まれる複数の可動ガイドロール８は、同じ方向に移動可能であってもよいし、異なる方向に移動可能であってもよい。また、これらの可動ガイドロール８の可動距離も同じであってもよいし、異なっていてもよい。 It is preferable that each of the first chamber 4a and the second chamber 4b includes at least one movable guide roll 8 described above so that the transport path length of the PVA film 1 in each chamber can be freely changed. All of the guide rolls provided in the first chamber 4a may be the movable guide roll 8, and all of the guide rolls provided in the second chamber 4b may be the movable guide roll 8. The first chamber 4a and the second chamber 4b each have two or more movable guide rolls 8 because the change in the transfer path length can be further increased and the transfer path length can be controlled more precisely. preferable. The plurality of movable guide rolls 8 included in the first chamber 4a and the second chamber 4b may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
　導出口６側の第２室４ｂ内の相対湿度は、導入口５側の第１室４ａ内の相対湿度より大きいことが好ましい。相対湿度のより低い第１室４ａを通過させた後に相対湿度のより高い第２室４ｂを通過させることにより、ＰＶＡフィルム１の加湿をより効率的に行うことができる。 The relative humidity in the second chamber 4b on the outlet 6 side is preferably larger than the relative humidity in the first chamber 4a on the inlet 5 side. The PVA film 1 can be humidified more efficiently by passing the second chamber 4b having a higher relative humidity after passing the first chamber 4a having a lower relative humidity.
　加湿装置３は、図４に示される第１室４ａと第２室４ｂとの間に第３室を設けるなど、３以上の室（チャンバ）で構成されていてもよい。３以上の室は、好ましくはそれぞれ独立して室内の相対湿度を調整可能なものであり、より好ましくは室内の相対湿度とともに内部温度を調整可能なものである。また、各室内でのＰＶＡフィルム１の搬送経路長を自在に変化させることができるよう、各室はそれぞれ、上述の可動ガイドロール８を少なくとも１つ備えることが好ましい。搬送経路長の変化をより大きくできる点、及び搬送経路長をより緻密に制御できる点から、各室はそれぞれ、可動ガイドロール８を２以上有していることが好ましい。３以上の室に含まれる複数の可動ガイドロール８は、同じ方向に移動可能であってもよいし、異なる方向に移動可能であってもよい。また、これらの可動ガイドロール８の可動距離も同じであってもよいし、異なっていてもよい。 The humidifier 3 may be composed of three or more chambers (chambers) such as providing a third chamber between the first chamber 4a and the second chamber 4b shown in FIG. The three or more chambers are preferably capable of independently adjusting the relative humidity in the room, and more preferably capable of adjusting the internal temperature together with the relative humidity in the room. Moreover, it is preferable that each chamber is provided with at least one movable guide roll 8 described above so that the transport path length of the PVA film 1 in each chamber can be freely changed. It is preferable that each chamber has two or more movable guide rolls 8 because the change in the conveyance path length can be further increased and the conveyance path length can be more precisely controlled. The plurality of movable guide rolls 8 included in three or more chambers may be movable in the same direction or may be movable in different directions. Further, the movable distances of these movable guide rolls 8 may be the same or different.
　加湿装置３を用いる場合において、加湿フィルムを得る工程Ｓ１０は、図１を参照して、好ましくは、加湿装置３から導出された加湿フィルム２の水分率を検出する工程Ｓ１０２と、検出する工程Ｓ１０２で得られる検出結果に基づいて、可動ガイドロール８の位置を制御する工程Ｓ１０３とをさらに含む。工程Ｓ１０２及び工程Ｓ１０３は、上述の加湿装置３を含む加湿システムを用いて行うことができる。 In the case where the humidifier 3 is used, the step S10 for obtaining the humidified film is preferably a step S102 for detecting the moisture content of the humidified film 2 derived from the humidifier 3 with reference to FIG. Step S103 for controlling the position of the movable guide roll 8 based on the detection result obtained in step S103. Process S102 and process S103 can be performed using the humidification system containing the humidification apparatus 3 mentioned above.
　図２及び図４に示されるように、加湿システムは、上述の加湿装置３を備える加湿部と、加湿装置３から導出される加湿フィルム２の水分率を検出する検出部１０と、検出部１０と加湿装置３が備える可動ガイドロール８とに接続され、検出部１０による検出結果に基づいて可動ガイドロール８の位置を制御する制御部２０とを含む。工程Ｓ１０２は検出部１０によって行うことができ、工程Ｓ１０３は制御部２０によって行うことができる。 As shown in FIGS. 2 and 4, the humidifying system includes a humidifying unit including the humidifying device 3 described above, a detecting unit 10 that detects the moisture content of the humidifying film 2 derived from the humidifying device 3, and the detecting unit 10. And a control unit 20 that controls the position of the movable guide roll 8 based on the detection result of the detection unit 10. Step S102 can be performed by the detection unit 10, and step S103 can be performed by the control unit 20.
　Ｓ１０１～Ｓ１０３の一連の工程を含む加湿フィルム２の作製方法は、所望の水分率を有する加湿フィルム２を連続的に、かつ安定的に製造するうえで有利である。すなわち、この方法によれば、検出する工程Ｓ１０２で得られる検出結果に基づいて、加湿フィルム２の水分率が所望値（又は所望範囲内）となるように可動ガイドロール８の位置、従ってＰＶＡフィルム１の搬送経路長をフィードバック制御することができる。 The method for producing the humidified film 2 including the series of steps S101 to S103 is advantageous for continuously and stably producing the humidified film 2 having a desired moisture content. That is, according to this method, based on the detection result obtained in the detecting step S102, the position of the movable guide roll 8 so that the moisture content of the humidifying film 2 becomes a desired value (or within a desired range), and thus the PVA film. One conveyance path length can be feedback-controlled.
　Ｓ１０１～Ｓ１０３の一連の工程を含む加湿フィルムを得る工程Ｓ１０の具体的フローは例えば次のとおりである。まず、加湿装置３内でのＰＶＡフィルム１の搬送経路長を調整することによって、水分率が調整された加湿フィルム２を製造する（工程Ｓ１０１）。次いで、導出口６から導出された加湿フィルム２の水分率を検出部１０によって検出し（工程Ｓ１０２）、水分率検出値が所望値又は所望範囲内であるか否かを判定する。この判定は、検出部１０が行うようにしてもよいし、制御部２０が行うようにしてもよい。水分率検出値が所望値又は所望範囲内である場合、工程Ｓ１０３において制御部２０は、可動ガイドロール８の位置を変化させずに維持する。一方、水分率検出値が所望値又は所望範囲内でない場合、工程Ｓ１０３において制御部２０は、可動ガイドロール８の位置を調整してチャンバ４内でのＰＶＡフィルム１の搬送経路長を変化させる。具体的には制御部２０は、水分率検出値が所望値又は所望範囲よりも大きい場合にはＰＶＡフィルム１の搬送経路長が短くなるように、水分率検出値が所望値又は所望範囲よりも小さい場合にはＰＶＡフィルム１の搬送経路長が長くなるように可動ガイドロール８の位置を調整する。そして、好ましくはＰＶＡフィルム１の搬送経路長を変化させた後に、再度、検出部１０によって加湿フィルム２の水分率を検出し、水分率検出値が所望値又は所望範囲内であるか否かを確認する。以上の制御を水分率検出値が所望値又は所望範囲内となるまで繰り返す。 A specific flow of step S10 for obtaining a humidified film including a series of steps S101 to S103 is, for example, as follows. First, the humidification film 2 in which the moisture content is adjusted is manufactured by adjusting the transport path length of the PVA film 1 in the humidifier 3 (step S101). Next, the moisture content of the humidified film 2 derived from the outlet 6 is detected by the detection unit 10 (step S102), and it is determined whether or not the moisture content detection value is within a desired value or a desired range. This determination may be performed by the detection unit 10 or may be performed by the control unit 20. When the moisture content detection value is within the desired value or the desired range, the control unit 20 maintains the position of the movable guide roll 8 without changing in step S103. On the other hand, when the moisture content detection value is not within the desired value or the desired range, in step S103, the control unit 20 adjusts the position of the movable guide roll 8 to change the transport path length of the PVA film 1 in the chamber 4. Specifically, the control unit 20 determines that the moisture content detection value is smaller than the desired value or the desired range so that the transport path length of the PVA film 1 becomes shorter when the moisture content detection value is larger than the desired value or the desired range. When it is small, the position of the movable guide roll 8 is adjusted so that the transport path length of the PVA film 1 becomes long. And preferably after changing the conveyance path length of the PVA film 1, the moisture content of the humidified film 2 is detected again by the detection unit 10, and whether or not the moisture content detection value is within a desired value or a desired range. Check. The above control is repeated until the moisture content detection value becomes a desired value or within a desired range.
　好ましくは、検出部１０は、加湿フィルム２の水分率を連続的に、あるいは、ある時間間隔毎に継続的に検出し、これに応じて制御部２０は、可動ガイドロール８の位置に係るフィードバック制御を連続的に、あるいは、ある時間間隔毎に継続的に行う。 Preferably, the detection unit 10 detects the moisture content of the humidified film 2 continuously or continuously at certain time intervals, and in response thereto, the control unit 20 feedbacks the position of the movable guide roll 8. Control is performed continuously or continuously at certain time intervals.
　可動ガイドロール８の位置を調整してチャンバ４内でのＰＶＡフィルム１の搬送経路長を変化させるにあたっては、ＰＶＡフィルム１の搬送経路長の変化量と加湿フィルム２の水分率の変化量との相関関係を予め調べておき、これに基づいて搬送経路長の変化量を決定してもよい。加湿装置３が複数の可動ガイドロール８を備える場合、位置移動させる可動ガイドロール８やその数、個々の可動ガイドロール８の移動距離などは、ＰＶＡフィルム１の搬送経路長の変化量が所定値となるよう適宜選択される。 In changing the transport path length of the PVA film 1 in the chamber 4 by adjusting the position of the movable guide roll 8, the change amount of the transport path length of the PVA film 1 and the change amount of the moisture content of the humidified film 2 are calculated. The correlation may be examined in advance, and the amount of change in the conveyance path length may be determined based on the correlation. When the humidifying device 3 includes a plurality of movable guide rolls 8, the amount of change in the transport path length of the PVA film 1 is a predetermined value for the movable guide rolls 8 to be moved, the number of the movable guide rolls 8, the moving distance of the individual movable guide rolls 8, and the like. It chooses suitably so that it may become.
　検出部１０は、加湿装置３から導出された加湿フィルム２を搬送しながらインラインで水分率を検出できるものであることが好ましく、このようなものとして赤外線吸収式の水分率計を好適に用いることができる。上述の水分率検出値として、赤外線吸収式の水分率計による水分率を採用してもよいし、あるいは、赤外線吸収式の水分率計による水分率と乾燥重量法に従う水分率との相関を示す検量線を予め作成しておき、この検量線によって換算される乾燥重量法に従う水分率を水分率検出値として採用してもよい。 The detection unit 10 is preferably capable of detecting the moisture content in-line while transporting the humidified film 2 derived from the humidifier 3, and as such, an infrared absorption moisture meter is preferably used. Can do. The moisture content detected by the infrared absorption type moisture meter may be adopted as the moisture content detection value described above, or the correlation between the moisture content by the infrared absorption type moisture meter and the moisture content according to the dry weight method is shown. A calibration curve may be prepared in advance, and the moisture content according to the dry weight method converted by this calibration curve may be adopted as the moisture content detection value.
　乾燥重量法に従う水分率は、１０５℃で２時間乾燥させたときのフィルムの重量をＷ１、乾燥前のフィルムの重量をＷ０とするとき、次式：
　乾燥重量法による水分率（重量％）＝｛（Ｗ０－Ｗ１）÷Ｗ０｝×１００
に従って求められる。 The moisture content according to the dry weight method is expressed by the following formula when the weight of the film when dried at 105 ° C. for 2 hours is W1, and the weight of the film before drying is W0:
Moisture content by dry weight method (wt%) = {(W0−W1) ÷ W0} × 100
As required.
　制御部２０は、検出部１０からの信号を受信することができ、これに基づいて可動ガイドロール８の位置を制御するコンピュータなどであることができる。 The control unit 20 can be a computer that can receive a signal from the detection unit 10 and controls the position of the movable guide roll 8 based on the signal.
　図示されていないが、フィルム加湿システムは、加湿装置３の上流側に配置されるＰＶＡフィルム１を加熱するための加熱装置を含むことができる。ＰＶＡフィルム１を加熱装置に通した後に加湿装置３に導入することにより、加湿装置３に導入したときに生じ得るＰＶＡフィルム１表面の結露をより効果的に抑制又は防止することができる。上記加熱装置は、内部温度を調整可能な加熱チャンバ（熱風の供給により内部温度を高めることができる熱風オーブン等）、１又は２以上の熱ロール、ヒーター（赤外線ヒーター、ハロゲンヒーター、パネルヒーター等）などであることができる。 Although not shown, the film humidification system can include a heating device for heating the PVA film 1 disposed on the upstream side of the humidification device 3. By introducing the PVA film 1 into the humidifying device 3 after passing through the heating device, dew condensation on the surface of the PVA film 1 that may occur when the PVA film 1 is introduced into the humidifying device 3 can be more effectively suppressed or prevented. The above heating device is a heating chamber in which the internal temperature can be adjusted (such as a hot air oven that can increase the internal temperature by supplying hot air), one or more hot rolls, a heater (infrared heater, halogen heater, panel heater, etc.) And so on.
　加熱装置によるフィルム１の加熱温度は、例えば５０～１５０℃であり、好ましくは６０～１３０℃であり、より好ましくは７０～１２０℃である。加湿装置３に導入したときのＰＶＡフィルム１表面の結露を効果的に抑制又は防止するために、加熱装置によるＰＶＡフィルム１の加熱温度は、ＰＶＡフィルム１を加湿処理する際のチャンバ４の内部温度、及びチャンバ４内でのＰＶＡフィルム１の温度より、好ましくは１０℃以上、より好ましくは２０℃以上高い。 The heating temperature of the film 1 by the heating device is, for example, 50 to 150 ° C., preferably 60 to 130 ° C., more preferably 70 to 120 ° C. In order to effectively suppress or prevent condensation on the surface of the PVA film 1 when introduced into the humidifier 3, the heating temperature of the PVA film 1 by the heating device is the internal temperature of the chamber 4 when the PVA film 1 is humidified. The temperature of the PVA film 1 in the chamber 4 is preferably 10 ° C. or higher, more preferably 20 ° C. or higher.
　加熱装置によるＰＶＡフィルム１の加熱処理は通常、チャンバ４内の相対湿度よりも低い相対湿度環境下で実施される。 The heat treatment of the PVA film 1 by the heating device is usually performed in a relative humidity environment lower than the relative humidity in the chamber 4.
　加湿フィルムを得る工程Ｓ１０で用いられる加湿装置は、当該加湿装置内でのＰＶＡフィルムの搬送経路長を変化させることができるものである限り制限されず、上記可動ガイドロール８を有する加湿装置３のほか、例えば、内部の相対湿度を調整可能なチャンバ内に移動させたり当該チャンバ外へ移動させたりすることが可能な、ＰＶＡフィルムの搬送経路を規定する１又は２以上のガイドロールを備えており、このガイドロールの出し入れによってチャンバ内でのＰＶＡフィルムの搬送経路長を自在に変化させることができるものであってもよい。ただし、設備の簡便さの観点から、上記可動ガイドロール８を有する加湿装置３を用いることが好ましい。 The humidifier used in step S10 for obtaining the humidified film is not limited as long as it can change the transport path length of the PVA film in the humidifier, and the humidifier 3 having the movable guide roll 8 is not limited. In addition, for example, it has one or more guide rolls that define a transport path of the PVA film that can be moved into and out of the chamber where the relative humidity inside can be adjusted. The guide path may be changed so that the transport path length of the PVA film in the chamber can be freely changed. However, it is preferable to use the humidifying device 3 having the movable guide roll 8 from the viewpoint of simplicity of equipment.
　得られる加湿フィルム２の水分率は、加湿フィルム２の厚みにもよるが、好ましくは４～１５重量％であり、より好ましくは５～１３重量％であり、７重量％以上、さらには８重量％以上であってもよい。 Although the moisture content of the obtained humidified film 2 depends on the thickness of the humidified film 2, it is preferably 4 to 15% by weight, more preferably 5 to 13% by weight, 7% by weight or more, and further 8% by weight. % Or more.
　（２）延伸フィルムを得る工程Ｓ２０
　延伸フィルムを得る工程Ｓ２０は、加湿フィルム２を乾式延伸することにより延伸フィルムを得る工程である。乾式延伸とは空中で行う延伸をいい、通常は縦一軸延伸である。乾式延伸としては、表面が加熱された熱ロールと、この熱ロールとは周速の異なるガイドロール（又は熱ロールであってもよい。）との間にフィルムを通し、熱ロールを利用した加熱下に縦延伸を行う熱ロール延伸；距離を置いて設置された２つのニップロール間にある加熱手段（オーブン等）を通過させながら、これら２つのニップロール間の周速差によって縦延伸を行うロール間延伸；テンター延伸；圧縮延伸等を挙げることができる。延伸温度（熱ロールの表面温度や、オーブン内温度等）は、例えば８０～１５０℃であり、好ましくは１００～１３５℃である。 (2) Step S20 for obtaining a stretched film
Step S20 for obtaining a stretched film is a step for obtaining a stretched film by dry-stretching the humidified film 2. Dry stretching refers to stretching performed in the air, and is usually longitudinal uniaxial stretching. As dry stretching, a film is passed between a heated roll whose surface is heated and a guide roll (or a heated roll) having a different peripheral speed from the heated roll, and heating using a heated roll. Hot roll stretching that performs longitudinal stretching below; Between rolls that perform longitudinal stretching due to the difference in peripheral speed between these two nip rolls while passing heating means (such as an oven) between two nip rolls installed at a distance. Stretching; tenter stretching; compression stretching and the like. The stretching temperature (the surface temperature of the hot roll, the temperature in the oven, etc.) is, for example, 80 to 150 ° C., preferably 100 to 135 ° C.
　加湿フィルム２の延伸倍率は、延伸フィルムを偏光フィルムの原料として使用する場合における偏光フィルムの光学特性（特に偏光特性）の観点から、好ましくは３．５倍以上であり、より好ましくは４倍以上である。延伸倍率は、通常８倍程度以下である。 The stretching ratio of the humidified film 2 is preferably 3.5 times or more, more preferably 4 times or more, from the viewpoint of optical properties (particularly polarization properties) of the polarizing film when the stretched film is used as a raw material for the polarizing film. It is. The draw ratio is usually about 8 times or less.
　長尺フィルムとして連続的に得られる延伸フィルムは、一旦巻き取ってフィルムロールとされてもよいし、巻き取ることなく引き続き、例えば偏光フィルム化工程などの次の工程に供給してもよい。 The stretched film continuously obtained as a long film may be wound up once to be a film roll, or may be continuously supplied to the next step such as a polarizing film forming step without being wound up.
　＜偏光フィルム及び偏光板の製造＞
　本発明に係る製造方法によって得られる延伸フィルムは、偏光フィルムの原料として好適に用いることができる。偏光フィルムは、延伸フィルムを二色性色素で染色することにより二色性色素を吸着させる工程；二色性色素が吸着されたフィルムを架橋処理する工程；及び、架橋処理後に水洗する工程、を経て製造することができる。二色性色素としては、ヨウ素又は二色性有機染料を用いることができる。 <Production of polarizing film and polarizing plate>
The stretched film obtained by the production method according to the present invention can be suitably used as a raw material for a polarizing film. The polarizing film includes a step of adsorbing the dichroic dye by dyeing the stretched film with the dichroic dye; a step of crosslinking the film on which the dichroic dye is adsorbed; and a step of washing with water after the crosslinking treatment. It can be manufactured after that. As the dichroic dye, iodine or a dichroic organic dye can be used.
　延伸フィルムを二色性色素で染色する方法としては、例えば、延伸フィルムを二色性色素が含有された水溶液（染色溶液）に浸漬する方法が採用される。延伸フィルムは、染色処理の前に水への浸漬処理（膨潤処理）を施しておくことが好ましい。 As a method of dyeing the stretched film with a dichroic dye, for example, a method of immersing the stretched film in an aqueous solution (dye solution) containing the dichroic dye is employed. The stretched film is preferably subjected to an immersion treatment (swelling treatment) in water before the dyeing treatment.
　二色性色素としてヨウ素を用いる場合は、通常、ヨウ素及びヨウ化カリウムを含有する水溶液に、延伸フィルムを浸漬して染色する方法が採用される。この染色水溶液におけるヨウ素の含有量は、水１００重量部あたり通常０．０１～１重量部である。また、ヨウ化カリウムの含有量は、水１００重量部あたり通常０．５～２０重量部である。染色水溶液の温度は、通常２０～４０℃程度である。 When iodine is used as the dichroic dye, a method of dyeing a stretched film in an aqueous solution containing iodine and potassium iodide is usually employed. The iodine content in this dyeing aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the dyeing aqueous solution is usually about 20 to 40 ° C.
　一方、二色性色素として二色性有機染料を用いる場合は、通常、水溶性の二色性有機染料を含む染色水溶液に、延伸フィルムを浸漬して染色する方法が採用される。染色水溶液における二色性有機染料の含有量は、水１００重量部あたり通常１×１０-4～１０重量部であり、好ましくは１×１０-3～１重量部である。この染色水溶液は、硫酸ナトリウム等の無機塩を染色助剤として含有していてもよい。染色水溶液の温度は、通常２０～８０℃程度である。 On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of dyeing a stretched film in a dyeing aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in the aqueous dyeing solution is usually 1 × 10 −4 to 10 parts by weight, preferably 1 × 10 −3 to 1 part by weight per 100 parts by weight of water. This dyeing aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dyeing aqueous solution is usually about 20 to 80 ° C.
　二色性色素による染色後の架橋処理は、染色されたフィルムを架橋剤含有水溶液に浸漬することにより行うことができる。架橋剤の好適な例はホウ酸であるが、ホウ砂のようなホウ素化合物、グリオキザール、グルタルアルデヒド等の他の架橋剤を用いることもできる。架橋剤は１種のみを使用してもよいし、２種以上を併用してもよい。 The crosslinking treatment after dyeing with a dichroic dye can be performed by immersing the dyed film in an aqueous solution containing a crosslinking agent. A suitable example of the cross-linking agent is boric acid, but other cross-linking agents such as boron compounds such as borax, glyoxal, and glutaraldehyde can also be used. Only 1 type may be used for a crosslinking agent and it may use 2 or more types together.
　架橋剤含有水溶液における架橋剤の量は、水１００重量部あたり通常２～１５重量部であり、好ましくは５～１２重量部である。二色性色素としてヨウ素を用いる場合、この架橋剤含有水溶液はヨウ化カリウムを含有することが好ましい。架橋剤含有水溶液におけるヨウ化カリウムの量は、水１００重量部あたり通常０．１～１５重量部であり、好ましくは５～１２重量部である。架橋剤含有水溶液の温度は、通常５０℃以上であり、好ましくは５０～８５℃である。 The amount of the crosslinking agent in the aqueous solution containing the crosslinking agent is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous solution containing a crosslinking agent preferably contains potassium iodide. The amount of potassium iodide in the crosslinking agent-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution containing a crosslinking agent is usually 50 ° C. or higher, preferably 50 to 85 ° C.
　架橋処理後のフィルムは通常、水洗処理される。水洗処理は、例えば、架橋処理されたポリビニルアルコール系樹脂フィルムを水に浸漬することにより行うことができる。水洗処理における水の温度は通常、１～４０℃程度である。 The film after the crosslinking treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the crosslinked polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 1 to 40 ° C.
　膨潤処理、染色処理、架橋処理及び洗浄処理のいずれか１以上の処理において、必要に応じてフィルムに湿式延伸を施してもよい。 In any one or more of swelling treatment, dyeing treatment, crosslinking treatment and washing treatment, the film may be subjected to wet stretching as necessary.
　水洗後に乾燥処理を施して、偏光フィルムが得られる。乾燥処理は、熱風乾燥機による乾燥、熱ロールに接触させることによる乾燥、遠赤外線ヒーターによる乾燥などであることができる。乾燥処理の温度は、通常３０～１００℃程度であり、５０～９０℃が好ましい。偏光フィルムの厚みは、通常２～４０μｍ程度である。偏光板の薄膜化の観点から、偏光フィルムの厚みは、好ましくは２０μｍ以下であり、より好ましくは１５μｍ以下であり、さらに好ましくは１０μｍ以下である。 A polarizing film is obtained by performing a drying treatment after washing with water. The drying treatment can be drying with a hot air dryer, drying by contacting with a hot roll, drying with a far infrared heater, and the like. The temperature for the drying treatment is usually about 30 to 100 ° C., preferably 50 to 90 ° C. The thickness of the polarizing film is usually about 2 to 40 μm. From the viewpoint of thinning the polarizing plate, the thickness of the polarizing film is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.
　偏光フィルムの片面又は両面に接着剤層を介して熱可塑性樹脂フィルムを貼合することにより偏光板を得ることができる。熱可塑性樹脂フィルムは、透光性を有する熱可塑性樹脂、好ましくは光学的に透明な熱可塑性樹脂で構成されるフィルムである。熱可塑性樹脂フィルムを構成する熱可塑性樹脂は、例えば、鎖状ポリオレフィン系樹脂（ポリプロピレン系樹脂等）、環状ポリオレフィン系樹脂（ノルボルネン系樹脂等）のようなポリオレフィン系樹脂；トリアセチルセルロース、ジアセチルセルロースのようなセルロース系樹脂；ポリエチレンテレフタレート、ポリブチレンテレフタレートのようなポリエステル系樹脂；ポリカーボネート系樹脂；メタクリル酸メチル系樹脂のような（メタ）アクリル系樹脂；ポリスチレン系樹脂；ポリ塩化ビニル系樹脂；アクリロニトリル・ブタジエン・スチレン系樹脂；アクリロニトリル・スチレン系樹脂；ポリ酢酸ビニル系樹脂；ポリ塩化ビニリデン系樹脂；ポリアミド系樹脂；ポリアセタール系樹脂；変性ポリフェニレンエーテル系樹脂；ポリスルホン系樹脂；ポリエーテルスルホン系樹脂；ポリアリレート系樹脂；ポリアミドイミド系樹脂；ポリイミド系樹脂等であることができる。 A polarizing plate can be obtained by bonding a thermoplastic resin film to one or both sides of a polarizing film via an adhesive layer. The thermoplastic resin film is a film composed of a thermoplastic resin having translucency, preferably an optically transparent thermoplastic resin. The thermoplastic resin constituting the thermoplastic resin film is, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like); triacetyl cellulose or diacetyl cellulose. Cellulose resins such as: Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resins; (Meth) acrylic resins such as methyl methacrylate resins; Polystyrene resins; Polyvinyl chloride resins; Acrylonitrile Butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; Hong resins; poly (ether sulfone) resins; polyarylate resin; polyamideimide resin; may be a polyimide resin or the like.
　鎖状ポリオレフィン系樹脂としては、ポリエチレン樹脂、ポリプロピレン樹脂のような鎖状オレフィンの単独重合体のほか、２種以上の鎖状オレフィンからなる共重合体を挙げることができる。より具体的な例は、ポリプロピレン系樹脂（プロピレンの単独重合体であるポリプロピレン樹脂や、プロピレンを主体とする共重合体）、ポリエチレン系樹脂（エチレンの単独重合体であるポリエチレン樹脂や、エチレンを主体とする共重合体）を含む。 Examples of the chain polyolefin resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins. More specific examples include polypropylene resins (polypropylene resins that are homopolymers of propylene and copolymers mainly composed of propylene), polyethylene resins (polyethylene resins that are homopolymers of ethylene and ethylene mainly) A copolymer).
　環状ポリオレフィン系樹脂は、環状オレフィンを重合単位として重合される樹脂の総称である。環状ポリオレフィン系樹脂の具体例を挙げれば、環状オレフィンの開環（共）重合体、環状オレフィンの付加重合体、環状オレフィンとエチレン、プロピレンのような鎖状オレフィンとの共重合体（代表的にはランダム共重合体）、及びこれらを不飽和カルボン酸やその誘導体で変性したグラフト重合体、並びにそれらの水素化物等である。中でも、環状オレフィンとしてノルボルネンや多環ノルボルネン系モノマー等のノルボルネン系モノマーを用いたノルボルネン系樹脂が好ましく用いられる。 Cyclic polyolefin-based resin is a general term for resins that are polymerized using cyclic olefins as polymerization units. Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.
　セルロース系樹脂とは、綿花リンタや木材パルプ（広葉樹パルプ、針葉樹パルプ）等の原料セルロースから得られるセルロースの水酸基における水素原子の一部または全部がアセチル基、プロピオニル基及び／又はブチリル基で置換された、セルロース有機酸エステル又はセルロース混合有機酸エステルをいう。例えば、セルロースの酢酸エステル、プロピオン酸エステル、酪酸エステル、及びそれらの混合エステル等からなるものが挙げられる。中でも、トリアセチルセルロース、ジアセチルセルロース、セルロースアセテートプロピオネート、セルロースアセテートブチレートが好ましい。 Cellulosic resins are those in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) are substituted with acetyl groups, propionyl groups and / or butyryl groups. Further, it refers to a cellulose organic acid ester or a cellulose mixed organic acid ester. For example, cellulose acetate, propionate, butyrate, and mixed esters thereof can be used. Among these, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferable.
　ポリエステル系樹脂は、エステル結合を有する、上記セルロース系樹脂以外の樹脂であり、多価カルボン酸又はその誘導体と多価アルコールとの重縮合体からなるものが一般的である。多価カルボン酸又はその誘導体としては２価のジカルボン酸又はその誘導体を用いることができ、例えばテレフタル酸、イソフタル酸、ジメチルテレフタレート、ナフタレンジカルボン酸ジメチル等が挙げられる。多価アルコールとしては２価のジオールを用いることができ、例えばエチレングリコール、プロパンジオール、ブタンジオール、ネオペンチルグリコール、シクロヘキサンジメタノール等が挙げられる。好適なポリエステル系樹脂の例は、ポリエチレンテレフタレートを含む。 The polyester-based resin is a resin other than the above cellulose-based resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.
　ポリカーボネート系樹脂は、カルボナート基を介してモノマー単位が結合された重合体からなるエンジニアリングプラスチックであり、高い耐衝撃性、耐熱性、難燃性、透明性を有する樹脂である。ポリカーボネート系樹脂は、光弾性係数を下げるためにポリマー骨格を修飾したような変性ポリカーボネートと呼ばれる樹脂や、波長依存性を改良した共重合ポリカーボネート等であってもよい。 Polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolymerized polycarbonate with improved wavelength dependency, or the like.
　（メタ）アクリル系樹脂は、（メタ）アクリル系モノマー由来の構成単位を含む重合体である。該重合体は、典型的にはメタクリル酸エステルを含む重合体である。好ましくはメタクリル酸エステルに由来する構造単位の割合が、全構造単位に対して、５０重量％以上含む重合体である。（メタ）アクリル系樹脂は、メタクリル酸エステルの単独重合体であってもよいし、他の重合性モノマー由来の構成単位を含む共重合体であってもよい。この場合、他の重合性モノマー由来の構成単位の割合は、好ましくは全構造単位に対して、５０重量％以下である。 (Meth) acrylic resin is a polymer containing structural units derived from (meth) acrylic monomers. The polymer is typically a polymer containing a methacrylic acid ester. Preferably, it is a polymer in which the proportion of structural units derived from methacrylic acid esters is 50% by weight or more based on the total structural units. The (meth) acrylic resin may be a methacrylic acid ester homopolymer or a copolymer containing structural units derived from other polymerizable monomers. In this case, the proportion of structural units derived from other polymerizable monomers is preferably 50% by weight or less based on the total structural units.
　（メタ）アクリル系樹脂を構成し得るメタクリル酸エステルとしては、メタクリル酸アルキルエステルが好ましい。メタクリル酸アルキルエステルとしては、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ－プロピル、メタクリル酸イソプロピル、メタクリル酸ｎ－ブチル、メタクリル酸イソブチル、メタクリル酸ｔ－ブチル、メタクリル酸２－エチルヘキシル、メタクリル酸シクロヘキシル、メタクリル酸２－ヒドロキシエチルのようなアルキル基の炭素数が１～８であるメタクリル酸アルキルエステルが挙げられる。メタクリル酸アルキルエステルに含まれるアルキル基の炭素数は、好ましくは１～４である。（メタ）アクリル系樹脂において、メタクリル酸エステルは、１種のみを単独で用いてもよいし２種以上を併用してもよい。 As the methacrylic acid ester that can constitute the (meth) acrylic resin, a methacrylic acid alkyl ester is preferable. Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate. And alkyl methacrylate having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl methacrylate. The carbon number of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, methacrylic acid esters may be used alone or in combination of two or more.
　（メタ）アクリル系樹脂を構成し得る上記他の重合性モノマーとしては、アクリル酸エステル、及びその他の分子内に重合性炭素－炭素二重結合を有する化合物を挙げることができる。他の重合性モノマーは、１種のみを単独で用いてもよいし２種以上を併用してもよい。アクリル酸エステルとしては、アクリル酸アルキルエステルが好ましい。アクリル酸アルキルエステルとしては、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－プロピル、アクリル酸イソプロピル、アクリル酸ｎ－ブチル、アクリル酸イソブチル、アクリル酸ｔ－ブチル、アクリル酸２－エチルヘキシル、アクリル酸シクロヘキシル、アクリル酸２－ヒドロキシエチルのようなアルキル基の炭素数が１～８であるアクリル酸アルキルエステルなどが挙げられる。アクリル酸アルキルエステルに含まれるアルキル基の炭素数は、好ましくは１～４である。（メタ）アクリル系樹脂において、アクリル酸エステルは、１種のみを単独で用いてもよいし２種以上を併用してもよい。 Examples of the other polymerizable monomer that can constitute the (meth) acrylic resin include acrylic acid esters and other compounds having a polymerizable carbon-carbon double bond in the molecule. Other polymerizable monomers may be used alone or in combination of two or more. As the acrylic acid ester, an acrylic acid alkyl ester is preferable. Examples of alkyl acrylate esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate. And alkyl acrylates having an alkyl group having 1 to 8 carbon atoms such as 2-hydroxyethyl acrylate. The number of carbon atoms of the alkyl group contained in the alkyl acrylate is preferably 1 to 4. In the (meth) acrylic resin, acrylic acid esters may be used alone or in combination of two or more.
　その他の分子内に重合性炭素－炭素二重結合を有する化合物としては、エチレン、プロピレン、スチレン等のビニル系化合物や、アクリロニトリルのようなビニルシアン化合物が挙げられる。その他の分子内に重合性炭素－炭素二重結合を有する化合物は、１種のみを単独で用いてもよいし２種以上を併用してもよい。 Other examples of the compound having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene and styrene, and vinylcyan compounds such as acrylonitrile. Other compounds having a polymerizable carbon-carbon double bond in the molecule may be used alone or in combination of two or more.
　熱可塑性樹脂フィルムは、偏光フィルムを保護するための保護フィルムであることができる。また、熱可塑性樹脂フィルムは、位相差フィルム、輝度向上フィルムのような光学機能を併せ持つ保護フィルムであることもできる。例えば、上記材料からなる熱可塑性樹脂フィルムを延伸（一軸延伸又は二軸延伸等）したり、該フィルム上に液晶層等を形成したりすることにより、任意の位相差値が付与された位相差フィルムとすることができる。熱可塑性樹脂フィルムは、その表面に積層される、ハードコート層、防眩層、反射防止層、帯電防止層、防汚層のような表面処理層（コーティング層）を有していてもよい。 The thermoplastic resin film can be a protective film for protecting the polarizing film. The thermoplastic resin film can also be a protective film having an optical function such as a retardation film and a brightness enhancement film. For example, a retardation provided with an arbitrary retardation value by stretching (such as uniaxial stretching or biaxial stretching) a thermoplastic resin film made of the above materials or forming a liquid crystal layer or the like on the film. It can be a film. The thermoplastic resin film may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or an antifouling layer, which is laminated on the surface.
　熱可塑性樹脂フィルムの厚みは通常１～１００μｍであるが、強度や取扱性、偏光板の薄膜化等の観点から５～６０μｍであることが好ましく、５～５０μｍであることがより好ましい。 The thickness of the thermoplastic resin film is usually 1 to 100 μm, but is preferably 5 to 60 μm and more preferably 5 to 50 μm from the viewpoints of strength, handleability, and thinning of the polarizing plate.
　偏光フィルムと熱可塑性樹脂フィルムとの貼合に用いる接着剤としては、水系接着剤、活性エネルギー線硬化性接着剤又は熱硬化性接着剤を用いることができ、好ましくは水系接着剤、活性エネルギー線硬化性接着剤である。 As an adhesive used for laminating the polarizing film and the thermoplastic resin film, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and preferably an aqueous adhesive, an active energy ray. It is a curable adhesive.
　水系接着剤は、接着剤成分を水に溶解したもの又は水に分散させたものである。好ましく用いられる水系接着剤は、例えば、主成分としてポリビニルアルコール系樹脂又はウレタン樹脂を用いた接着剤組成物である。 A water-based adhesive is one in which an adhesive component is dissolved in water or dispersed in water. The aqueous adhesive preferably used is, for example, an adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component.
　接着剤の主成分としてポリビニルアルコール系樹脂を用いる場合、当該ポリビニルアルコール系樹脂は、部分ケン化ポリビニルアルコール、完全ケン化ポリビニルアルコールのようなポリビニルアルコール樹脂であることができるほか、カルボキシル基変性ポリビニルアルコール、アセトアセチル基変性ポリビニルアルコール、メチロール基変性ポリビニルアルコール、アミノ基変性ポリビニルアルコールのような変性されたポリビニルアルコール系樹脂であってもよい。ポリビニルアルコール系樹脂は、酢酸ビニルの単独重合体であるポリ酢酸ビニルをケン化処理して得られるビニルアルコールホモポリマーのほか、酢酸ビニルとこれに共重合可能な他の単量体との共重合体をケン化処理して得られるポリビニルアルコール系共重合体であってもよい。 When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin can be a polyvinyl alcohol resin such as partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, or a carboxyl group-modified polyvinyl alcohol. Further, modified polyvinyl alcohol resins such as acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol may be used. Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymerization of vinyl acetate and other monomers copolymerizable therewith. It may be a polyvinyl alcohol copolymer obtained by saponifying the coalescence.
　ポリビニルアルコール系樹脂を接着剤成分とする水系接着剤は通常、ポリビニルアルコール系樹脂の水溶液である。接着剤中のポリビニルアルコール系樹脂の濃度は、水１００重量部に対して、通常１～１０重量部、好ましくは１～５重量部である。 An aqueous adhesive containing a polyvinyl alcohol resin as an adhesive component is usually an aqueous solution of a polyvinyl alcohol resin. The concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.
　ポリビニルアルコール系樹脂の水溶液からなる接着剤は、接着性を向上させるために、多価アルデヒド、メラミン系化合物、ジルコニア化合物、亜鉛化合物、グリオキザール、グリオキザール誘導体、水溶性エポキシ樹脂のような硬化性成分や架橋剤を含有することが好ましい。水溶性エポキシ樹脂としては、例えばジエチレントリアミン、トリエチレンテトラミン等のポリアルキレンポリアミンと、アジピン酸等のジカルボン酸との反応で得られるポリアミドアミンに、エピクロロヒドリンを反応させて得られるポリアミドポリアミンエポキシ樹脂を好適に用いることができる。かかるポリアミドポリアミンエポキシ樹脂の市販品としては、「スミレーズレジン６５０」（田岡化学工業（株）製）、「スミレーズレジン６７５」（田岡化学工業（株）製）、「ＷＳ－５２５」（日本ＰＭＣ（株）製）等が挙げられる。これら硬化性成分や架橋剤の添加量（硬化性成分及び架橋剤としてともに添加する場合にはその合計量）は、ポリビニルアルコール系樹脂１００重量部に対して、通常１～１００重量部、好ましくは１～５０重量部である。上記硬化性成分や架橋剤の添加量がポリビニルアルコール系樹脂１００重量部に対して１重量部未満である場合には、接着性向上の効果が小さくなる傾向にあり、また、当該添加量がポリビニルアルコール系樹脂１００重量部に対して１００重量部を超える場合には、接着剤層が脆くなる傾向にある。 Adhesives composed of aqueous solutions of polyvinyl alcohol resins are used to improve adhesiveness, such as curable components such as polyhydric aldehydes, melamine compounds, zirconia compounds, zinc compounds, glyoxal, glyoxal derivatives, and water-soluble epoxy resins. It is preferable to contain a crosslinking agent. Examples of water-soluble epoxy resins include polyamide polyamine epoxy resins obtained by reacting polychloroalkylenes such as diethylenetriamine and triethylenetetramine with polycarboxylic acid polyamines such as adipic acid and epichlorohydrin. Can be suitably used. Commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” (manufactured by Taoka Chemical Industry Co., Ltd.), “Smiles Resin 675” (manufactured by Taoka Chemical Industry Co., Ltd.), and “WS-525” (Japan). PMC Co., Ltd.). The addition amount of these curable components and crosslinking agents (the total amount when added as both the curable component and the crosslinking agent) is usually 1 to 100 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. 1 to 50 parts by weight. When the addition amount of the curable component or the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesiveness tends to be small, and the addition amount is polyvinyl. When it exceeds 100 parts by weight with respect to 100 parts by weight of the alcohol-based resin, the adhesive layer tends to become brittle.
　また、接着剤の主成分としてウレタン樹脂を用いる場合の好適な例として、ポリエステル系アイオノマー型ウレタン樹脂とグリシジルオキシ基を有する化合物との混合物を挙げることができる。ポリエステル系アイオノマー型ウレタン樹脂とは、ポリエステル骨格を有するウレタン樹脂であって、その中に少量のイオン性成分（親水成分）が導入されたものである。かかるアイオノマー型ウレタン樹脂は、乳化剤を使用せずに直接、水中で乳化してエマルジョンとなるため、水系の接着剤として好適である。 In addition, as a suitable example when a urethane resin is used as the main component of the adhesive, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group can be given. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion.
　活性エネルギー線硬化性接着剤は、紫外線、可視光、電子線、Ｘ線のような活性エネルギー線の照射によって硬化する接着剤である。活性エネルギー線硬化性接着剤を用いる場合、偏光板が有する接着剤層は、当該接着剤の硬化物層である。 The active energy ray-curable adhesive is an adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. When using an active energy ray-curable adhesive, the adhesive layer of the polarizing plate is a cured product layer of the adhesive.
　活性エネルギー線硬化性接着剤は、カチオン重合によって硬化するエポキシ系化合物を硬化性成分として含有する接着剤であることができ、好ましくは、かかるエポキシ系化合物を硬化性成分として含有する紫外線硬化性接着剤である。ここでいうエポキシ系化合物とは、分子内に平均１個以上、好ましくは２個以上のエポキシ基を有する化合物を意味する。エポキシ系化合物は、１種のみを使用してもよいし２種以上を併用してもよい。 The active energy ray curable adhesive can be an adhesive containing an epoxy compound that is cured by cationic polymerization as a curable component, and preferably an ultraviolet curable adhesive containing such an epoxy compound as a curable component. It is an agent. The epoxy compound here means a compound having an average of 1 or more, preferably 2 or more epoxy groups in the molecule. The epoxy compound may be used alone or in combination of two or more.
　好適に使用できるエポキシ系化合物の具体例は、芳香族ポリオールの芳香環に水素化反応を行って得られる脂環式ポリオールに、エピクロロヒドリンを反応させることにより得られる水素化エポキシ系化合物（脂環式環を有するポリオールのグリシジルエーテル）；脂肪族多価アルコール又はそのアルキレンオキサイド付加物のポリグリシジルエーテルのような脂肪族エポキシ系化合物；脂環式環に結合したエポキシ基を分子内に１個以上有するエポキシ系化合物である脂環式エポキシ系化合物を含む。 Specific examples of the epoxy compound that can be suitably used include a hydrogenated epoxy compound obtained by reacting epichlorohydrin with an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol ( A glycidyl ether of a polyol having an alicyclic ring); an aliphatic epoxy compound such as an aliphatic polyhydric alcohol or a polyglycidyl ether of an alkylene oxide adduct thereof; an epoxy group bonded to the alicyclic ring in the molecule 1 An alicyclic epoxy compound, which is an epoxy compound having at least one, is included.
　活性エネルギー線硬化性接着剤は、硬化性成分として、上記エポキシ系化合物の代わりに、又はこれとともにラジカル重合性である（メタ）アクリル系化合物を含有することができる。（メタ）アクリル系化合物としては、分子内に少なくとも１個の（メタ）アクリロイルオキシ基を有する（メタ）アクリレートモノマー；官能基含有化合物を２種以上反応させて得られ、分子内に少なくとも２個の（メタ）アクリロイルオキシ基を有する（メタ）アクリレートオリゴマー等の（メタ）アクリロイルオキシ基含有化合物を挙げることができる。 The active energy ray-curable adhesive can contain a radically polymerizable (meth) acrylic compound as a curable component, instead of or together with the epoxy compound. The (meth) acrylic compound is a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and at least two in the molecule. And (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having (meth) acryloyloxy groups.
　活性エネルギー線硬化性接着剤は、カチオン重合によって硬化するエポキシ系化合物を硬化性成分として含む場合、光カチオン重合開始剤を含有することが好ましい。光カチオン重合開始剤としては、例えば、芳香族ジアゾニウム塩；芳香族ヨードニウム塩や芳香族スルホニウム塩等のオニウム塩；鉄－アレン錯体等を挙げることができる。また、活性エネルギー線硬化性接着剤が（メタ）アクリル系化合物のようなラジカル重合性硬化性成分を含有する場合は、光ラジカル重合開始剤を含有することが好ましい。光ラジカル重合開始剤としては、例えば、アセトフェノン系開始剤、ベンゾフェノン系開始剤、ベンゾインエーテル系開始剤、チオキサントン系開始剤、キサントン、フルオレノン、カンファーキノン、ベンズアルデヒド、アントラキノン等を挙げることができる。 When the active energy ray-curable adhesive contains an epoxy compound that is cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes. Moreover, when the active energy ray-curable adhesive contains a radical polymerizable curable component such as a (meth) acrylic compound, it is preferable to contain a photo radical polymerization initiator. Examples of the photo radical polymerization initiator include acetophenone initiator, benzophenone initiator, benzoin ether initiator, thioxanthone initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like.
　偏光フィルムに熱可塑性樹脂フィルムを貼合するに先立って、偏光フィルム及び／又は熱可塑性樹脂フィルムの貼合面に、プラズマ処理、コロナ処理、紫外線照射処理、フレーム（火炎）処理、ケン化処理のような表面活性化処理を行ってもよい。この表面活性化処理により、偏光フィルムと熱可塑性樹脂フィルムとの接着性を高めることができる。 Prior to bonding the thermoplastic resin film to the polarizing film, the bonding surface of the polarizing film and / or thermoplastic resin film is subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, and saponification treatment. Such surface activation treatment may be performed. By this surface activation treatment, the adhesion between the polarizing film and the thermoplastic resin film can be enhanced.
　１　ポリビニルアルコール系樹脂フィルム（ＰＶＡフィルム）、２　加湿されたフィルム（加湿フィルム）、３　加湿装置、４　チャンバ、４ａ　チャンバの第１室、４ｂ　チャンバの第２室、５　導入口、６　導出口、７　非可動ガイドロール、８　可動ガイドロール、１０　検出部、２０　制御部。 1 polyvinyl alcohol resin film (PVA film), 2 humidified film (humidified film), 3 humidifier, 4 chamber, 4a chamber 1st chamber, 4b chamber 2nd chamber, 5 inlet, 6 outlet, 7 non-movable guide rolls, 8 movable guide rolls, 10 detection units, 20 control units.

Claims (7)

  1. 　長尺のポリビニルアルコール系樹脂フィルムを連続的に加湿装置に導入して、加湿フィルムを得る工程と、
    　前記加湿装置から導出された前記加湿フィルムを乾式延伸して、延伸フィルムを得る工程と、
    を含み、
    　前記加湿フィルムを得る工程は、前記加湿装置内での前記ポリビニルアルコール系樹脂フィルムの搬送経路長を変化させることによって前記加湿フィルムの水分率を調整する工程を含む、延伸フィルムの製造方法。     A step of continuously introducing a long polyvinyl alcohol-based resin film into a humidifier to obtain a humidified film;
    Dry-stretching the humidified film derived from the humidifier to obtain a stretched film;
    Including
    The step of obtaining the humidified film includes a step of adjusting a moisture content of the humidified film by changing a transport path length of the polyvinyl alcohol resin film in the humidifier.
  2. 　前記加湿装置は、内部の相対湿度を調整可能なチャンバと、前記チャンバ内に配置され、前記ポリビニルアルコール系樹脂フィルムの搬送経路を規定する複数のガイドロールと、を備えており、
    　前記複数のガイドロールの少なくとも１つは、位置移動が可能な可動ガイドロールであり、
    　前記水分率を調整する工程は、前記可動ガイドロールの位置を調整することを含む、請求項１に記載の製造方法。     The humidifier includes a chamber capable of adjusting an internal relative humidity, and a plurality of guide rolls that are disposed in the chamber and define a conveyance path of the polyvinyl alcohol-based resin film,
    At least one of the plurality of guide rolls is a movable guide roll capable of moving the position,
    The manufacturing method according to claim 1, wherein the step of adjusting the moisture content includes adjusting a position of the movable guide roll.
  3. 　前記加湿フィルムを得る工程は、
    　前記加湿装置から導出された前記加湿フィルムの水分率を検出する工程と、
    　前記検出する工程で得られる検出結果に基づいて、前記可動ガイドロールの位置を制御する工程と、
    をさらに含む、請求項２に記載の製造方法。     The step of obtaining the humidified film comprises
    Detecting the moisture content of the humidified film derived from the humidifier;
    A step of controlling the position of the movable guide roll based on the detection result obtained in the detecting step;
    The manufacturing method according to claim 2, further comprising:
  4. 　前記水分率を検出する工程において前記水分率は、前記加湿装置から導出された前記加湿フィルムを搬送しながらインラインで検出する、請求項３に記載の製造方法。 The manufacturing method according to claim 3, wherein in the step of detecting the moisture content, the moisture content is detected in-line while conveying the humidified film derived from the humidifier.
  5. 　前記可動ガイドロールは、水平方向から傾いた方向へ平行移動可能である、請求項２～４のいずれか１項に記載の製造方法。 The manufacturing method according to any one of claims 2 to 4, wherein the movable guide roll is movable in a direction inclined from a horizontal direction.
  6. 　前記チャンバは、前記ポリビニルアルコール系樹脂フィルムが導入される側の第１室と、前記加湿フィルムを導出する側の第２室と、を含み、
    　前記第２室内の相対湿度は、前記第１室内の相対湿度よりも高い、請求項２～５のいずれか１項に記載の製造方法。     The chamber includes a first chamber on the side where the polyvinyl alcohol-based resin film is introduced, and a second chamber on the side where the humidified film is led out,
    The manufacturing method according to any one of claims 2 to 5, wherein a relative humidity in the second room is higher than a relative humidity in the first room.
  7. 　前記第１室及び前記第２室のそれぞれが前記可動ガイドロールを備える、請求項６に記載の製造方法。 The manufacturing method according to claim 6, wherein each of the first chamber and the second chamber includes the movable guide roll.
PCT/JP2016/065260 2015-06-19 2016-05-24 Production method for stretched film WO2016203909A1 (en)

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JP2009276652A (en) * 2008-05-16 2009-11-26 Lintec Corp Light irradiation method, method for producing optical film, and light irradiation device
JP2013071314A (en) * 2011-09-28 2013-04-22 Sumitomo Chemical Co Ltd Acrylic resin film, method of producing the same, and polarizing plate using the same
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