WO2016021432A1 - 偏光フィルムの製造方法 - Google Patents

偏光フィルムの製造方法 Download PDF

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Publication number
WO2016021432A1
WO2016021432A1 PCT/JP2015/071223 JP2015071223W WO2016021432A1 WO 2016021432 A1 WO2016021432 A1 WO 2016021432A1 JP 2015071223 W JP2015071223 W JP 2015071223W WO 2016021432 A1 WO2016021432 A1 WO 2016021432A1
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Prior art keywords
film
polyvinyl alcohol
bath
roll
treatment
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PCT/JP2015/071223
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English (en)
French (fr)
Japanese (ja)
Inventor
圭二 網谷
直紀 吉田
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住友化学株式会社
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Application filed by 住友化学株式会社 filed Critical 住友化学株式会社
Priority to JP2016540157A priority Critical patent/JP6294491B2/ja
Priority to CN201580040056.2A priority patent/CN106575008B/zh
Priority to KR1020177003283A priority patent/KR101990222B1/ko
Publication of WO2016021432A1 publication Critical patent/WO2016021432A1/ja

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors

Definitions

  • the present invention relates to a method for producing a polarizing film that can be used as a constituent member of a polarizing plate.
  • a polarizing film obtained by adsorbing and orienting a dichroic dye such as iodine or a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film.
  • a polarizing film is usually a polarizing plate obtained by laminating a protective film on one or both sides using an adhesive, and is used for image display devices such as liquid crystal televisions, monitors for personal computers, and liquid crystal display devices such as mobile phones. It is used.
  • Patent Document 1 discloses a method in which a polyvinyl alcohol resin film is immersed in water at 30 ° C. for 5 minutes in order to suppress the curling of the film edge that occurs during the stretching of the polyvinyl alcohol resin film and to enable uniform stretching. It is disclosed that the curl angle is 180 ° or less.
  • the polarizing film is continuously unwound from the roll (rolled product) of the polyvinyl alcohol-based resin film while being transported along the film transport path passing through the various treatment baths as described above, and is also used as a swelling bath.
  • a continuous production can be carried out by applying a stretching treatment at any one or more stages from the immersion to the withdrawal from the crosslinking bath.
  • the film may break during continuous production, particularly during the stretching process, and improvements have been demanded from the viewpoint of productivity and the yield of the polarizing film.
  • the problem of film breakage during the stretching process is particularly remarkable when the thickness of the polyvinyl alcohol-based resin film is small.
  • an object of the present invention is to provide a method for producing a polarizing film that can effectively suppress film breakage during stretching even when a thin polyvinyl alcohol-based resin film is used.
  • This invention provides the manufacturing method of the polarizing film shown below.
  • the manufacturing method of a polarizing film whose curl angle in at least one of the film width direction both ends when the said polyvinyl alcohol-type resin film immerses in a swelling bath is less than 90 degrees.
  • the polyvinyl alcohol-based resin film is subjected to a drying treatment between the time when the polyvinyl alcohol-based resin film is unwound from a raw roll and immersed in a swelling bath.
  • [1] or [2] The manufacturing method as described.
  • the polyvinyl alcohol-based resin film is subjected to a widening process between the time when the polyvinyl alcohol-based resin film is unwound from the raw fabric roll and immersed in a swelling bath.
  • the manufacturing method in any one.
  • the polyvinyl alcohol-based resin film unwound from the raw fabric roll is immersed in a swelling bath by being conveyed along two or more rolls selected from a guide roll and a nip roll, Regarding the two or more rolls, L is 2 m or less, or T is 30 seconds, where L is the maximum distance between adjacent rolls and T is the maximum time required for conveyance between adjacent rolls.
  • the method of the present invention it is possible to effectively suppress film breakage at the time of stretching treatment, which has conventionally occurred in a method for producing a polarizing film from a thin polyvinyl alcohol-based resin film.
  • the polarizing film is one in which a dichroic dye (iodine or dichroic dye) is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film.
  • the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film is usually obtained by saponifying a polyvinyl acetate-based resin.
  • the degree of saponification is usually about 85 mol% or more, preferably about 90 mol% or more, more preferably about 99 mol% or more.
  • the polyvinyl acetate resin can be, for example, a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and another monomer copolymerizable therewith.
  • examples of other copolymerizable monomers include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids.
  • the degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10,000, preferably about 1500 to 5,000.
  • polyvinyl alcohol resins may be modified.
  • polyvinyl formal modified with aldehydes polyvinyl acetal, polyvinyl butyral, and the like may be used.
  • an unstretched polyvinyl alcohol-based resin film (raw fabric) having a thickness of 65 ⁇ m or less (for example, 60 ⁇ m or less), preferably 50 ⁇ m or less, more preferably 35 ⁇ m or less, and even more preferably 30 ⁇ m or less is used as a starting material for manufacturing a polarizing film. Film).
  • a thin polarizing film whose market demand is increasing. The thinner the original film, the easier it is to break the film during the stretching process.
  • the film can be effectively suppressed even when the original film is thin.
  • the raw film may be a polyvinyl alcohol-based resin film that has been previously stretched in the gas phase.
  • the width of the original film is not particularly limited and can be, for example, about 400 to 6000 mm. However, the larger the film width, the more likely the film breaks during the stretching process.
  • the raw fabric film is prepared as a roll (raw fabric roll) of a long unstretched polyvinyl alcohol resin film.
  • the polarizing film is a long film by carrying out a predetermined processing step by continuously conveying the long original film from the original film roll along the film conveying path of the polarizing film manufacturing apparatus. It can be continuously produced as a polarizing film.
  • the predetermined treatment steps include a swelling treatment step in which the original film is dipped in a swelling bath, a drawing treatment step in which the film after the swelling treatment step is dipped in the dyeing bath, and a drawing treatment step in which the film after the dyeing treatment is drawn is a crosslinking bath. It is possible to include a cross-linking treatment step that is drawn out after being immersed in the substrate.
  • a uniaxial stretching process is performed in a wet or dry manner between these series of processing steps (that is, before and after any one or more processing steps and / or during any one or more processing steps).
  • Other processing steps may be added as necessary.
  • Each of the above treatment steps may be a treatment of immersing the film in one bath or a treatment of sequentially immersing in two or more baths.
  • FIG. 1 is a sectional view showing typically an example of the manufacturing method of the polarizing film concerning the present invention, and the polarizing film manufacturing device used for it.
  • the polarizing film manufacturing apparatus shown in FIG. 1 transports a raw fabric (unstretched) film 10 made of polyvinyl alcohol resin along a film transport path while continuously unwinding from a raw fabric roll 11.
  • a swelling bath 13, a dyeing bath 15, a crosslinking bath 17, and a washing bath 19 provided on the conveyance path are sequentially passed, and finally, a drying furnace 21 is passed.
  • the obtained polarizing film 23 can be conveyed, for example, to the next polarizing plate production step (step of bonding a protective film on one or both sides of the polarizing film 23) as it is.
  • the arrow in FIG. 1 has shown the conveyance direction of the film.
  • FIG. 1 shows an example in which one bath is provided for each of the swelling bath 13, the dyeing bath 15, the crosslinking bath 17, and the washing bath 19, but if necessary, any one or more treatment baths (swelling bath 13).
  • the baths containing the treatment liquid for treating the polyvinyl alcohol-based resin film provided on the film conveyance path, such as the dyeing bath 15, the crosslinking bath 17, and the washing bath 19, are also collectively referred to as “treatment bath”. .) May be provided in two or more tanks.
  • the film transport path of the polarizing film manufacturing apparatus includes guide rolls 30 to 41, 60, 61 that can support the film to be transported or can further change the film transport direction in addition to the processing bath, and the film to be transported.
  • Guide rolls and nip rolls can be arranged before and after each treatment bath or in the treatment bath, whereby the film can be introduced and immersed in the treatment bath and drawn out from the treatment bath (see FIG. 1). For example, by providing one or more guide rolls in each treatment bath and transporting the film along these guide rolls, the film can be immersed in each treatment bath.
  • nip rolls are arranged before and after each treatment bath (nip rolls 50 to 54), whereby the nip rolls arranged before and after any one or more treatment baths. It is possible to perform inter-roll stretching in which longitudinal uniaxial stretching is performed with a difference in peripheral speed between them.
  • each processing step will be described.
  • the swelling treatment is performed for the purpose of removing foreign matter on the surface of the original film 10, removing the plasticizer in the original film 10, imparting easy dyeability, and plasticizing the original film 10.
  • the processing conditions are determined within a range in which the object can be achieved and within a range in which problems such as extreme dissolution and devitrification of the raw film 10 do not occur.
  • the original film 10 in the swelling treatment, the original film 10 is continuously unwound from the original roll 11 and conveyed along the film conveyance path, and the original film 10 is accommodated in the swelling bath 13 (swelled in a swelling tank). In the treated liquid) for a predetermined time and then withdrawing.
  • the raw film 10 is conveyed along the film conveyance path constructed by the guide rolls 60 and 61 and the nip roll 50 until the original film 10 is unwound and immersed in the swelling bath 13. Is done.
  • the film In the swelling process, the film is transported along the film transport path constructed by the guide rolls 30 to 32.
  • the swelling bath 13 contains boric acid (JP-A-10-153709), chloride (JP-A-06-281816), inorganic acid, inorganic salt, water-soluble organic solvent, alcohols, and the like. It is also possible to use an aqueous solution added in the range of about 0.01 to 10% by weight.
  • the temperature of the swelling bath 13 is, for example, about 10 to 50 ° C., preferably about 10 to 40 ° C., more preferably about 15 to 30 ° C.
  • the immersion time of the raw film 10 is preferably about 10 to 300 seconds, more preferably about 20 to 200 seconds.
  • the temperature of the swelling bath 13 is, for example, about 20 to 70 ° C., preferably about 30 to 60 ° C.
  • the immersion time of the raw film 10 is preferably about 30 to 300 seconds, more preferably about 60 to 240 seconds.
  • the curl angle at at least one of both ends in the film width direction when the raw film 10 is immersed in the swelling bath 13 is less than 90 °.
  • the original film 10 unwound from the original roll 11 is usually in a state in which at least one of the both ends in the width direction (more typically both both ends in the width direction) is warped (floated), Alternatively, when the curl is further increased and curling occurs such that both ends in the width direction are warped toward the center in the width direction, the curl angle when the original film 10 is immersed in the swelling bath 13 is 90 °. By being less than this, film breakage during the stretching process can be suppressed.
  • the curl angles at both ends in the film width direction are less than 90 °.
  • the curl angle at at least one of both ends in the film width direction is preferably 80 ° or less, and more preferably less than 75 °. It is more preferable that the curl angles at both ends in the film width direction are less than 90 ° from immediately after being unwound from the raw fabric roll 11 until being immersed in the swelling bath 13.
  • FIG. 2 is a film cross-sectional view schematically showing how the polyvinyl alcohol-based resin film curls and its curl angle.
  • 2 shows an example in which both ends in the film width direction are curled.
  • FIG. 2A shows a case where the curl angle is 45 °
  • FIG. 2B shows a case where the curl angle is 90 °
  • FIG. (C) has shown the case where a curl angle is 150 degrees.
  • the curl angle is ⁇ °
  • the end of the curled film portion is oriented in the direction of ⁇ ° with respect to the extrapolated surface of the non-curled film surface. That means.
  • the curl angles at both ends in the width direction of the raw film 10 that is continuously immersed in the swelling bath 13 can be measured by the method described in the section of the examples.
  • the curl angle at least one (preferably both) of the both ends of the film width direction when the original film 10 is immersed in the swelling bath 13 to be less than 90 °
  • the atmosphere in the unwinding process from unwinding the original fabric film 10 from the original fabric roll 11 until being immersed in the swelling bath 13 is adjusted to an appropriate condition.
  • Preferred atmospheric conditions are a temperature of 23 ⁇ 5 ° C. and a relative humidity of 20 to 70% RH.
  • a more preferable relative humidity is 20 to 65% RH, and an even more preferable relative humidity is 25 to 60% RH.
  • the time required for the unwinding step (the time from when the original film 10 is unwound from the original roll 11 to when it is immersed in the swelling bath 13) is kept short. Shortening the time is advantageous in suppressing curl growth during the unwinding process, and is also advantageous from the viewpoint of production efficiency. In general, the thinner the raw film, the easier the curl grows during the unwinding process.
  • the required time is preferably 750 seconds or less, more preferably 600 seconds or less, and even more preferably 300 seconds or less when the original film 10 having a thickness of 35 ⁇ m to 65 ⁇ m is used.
  • the raw film 10 having a thickness of less than 35 ⁇ m is used, it is preferably 650 seconds or less, more preferably 300 seconds or less, and even more preferably 150 seconds or less.
  • the required time is usually 10 seconds or more, preferably 20 seconds or more. is there.
  • drying process refers to a process of lowering the moisture content of the original film 10 by volatilizing the moisture in the original film 10.
  • the drying treatment is advantageous in reducing or eliminating curling.
  • it is necessary to perform a drying process so that the degree of dryness of the curled surface of the original film 10 (that is, the degree of decrease in moisture content due to drying) is smaller than the surface on the opposite side.
  • the curled surface is a raw film surface including a surface on the inner side of the curl, and referring to FIG. 2, it is an upper main surface in the drawing.
  • the substrate film 10 to be conveyed is subjected to a widening process.
  • the widening treatment performed for the purpose of widening the film width is advantageous in reducing or eliminating curling when the raw film 10 is immersed in the swelling bath 13.
  • Examples of the widening process include using a roll having a widening function such as an expander roll, a spiral roll, or a crown roll as a guide roll, or using another widening apparatus such as a cross guider, a bend bar, or a tenter clip. .
  • a treatment using a roll having a widening function is preferable because it is simple.
  • a roll having a widening function can be used as the guide rolls 60 and / or 61 shown in FIG. 1, a roll having a widening function can be used.
  • the curled portion is forcibly pressed down on the transported original film 10.
  • This treatment is also advantageous in reducing or eliminating curling when the raw film 10 is immersed in the swelling bath 13, as with the widening treatment.
  • Specific methods include film transport using an apparatus such as a conveyor, a method of pressing a roll or bar (a rod-like object such as a roll that does not rotate itself) against a curled portion, air, nitrogen, Examples thereof include a method of injecting an inert gas with respect to the raw film 10 such as argon onto the curled portion.
  • the maximum distance L between adjacent rolls is the largest value among the distances between adjacent rolls.
  • the distance between adjacent rolls is determined as the distance between adjacent roll centers.
  • the center of a line connecting the centers of a pair of rolls constituting the nip roll is employed instead of the roll center.
  • L is usually 0.01 m or more, preferably 2 m or less, and more preferably 0.05 to 1.5 m.
  • the maximum time T required for conveyance between adjacent rolls is the time required for conveyance between adjacent rolls (in the example of FIG. 1, time T 1 required for conveyance from the guide roll 60 to the guide roll 61, and This is the largest value of the time T 2 ) required for conveyance from the guide roll 61 to the nip roll 50.
  • the time required for transporting between adjacent rolls is obtained as the time from leaving one of the adjacent rolls until contacting the other roll. T is usually 0.5 seconds or longer, preferably 30 seconds or shorter, and more preferably 0.1 to 20 seconds.
  • the unwinding step usually, one or more nip rolls arranged before being immersed in the swelling bath are conveyed while keeping the tension of the original film 10 constant.
  • the original roll 11 The tension applied to the raw film 10 between the nip roll and the nip roll disposed just before dipping in the swelling bath is made higher than the tension applied after the nip roll. Thereby, curl growth during the unwinding step can be suppressed.
  • the tension applied to the original film 10 between the original roll 11 and the nip roll disposed immediately before being immersed in the swelling bath is, for example, 5 to 300 N / mm, and preferably 10 to 200 N / mm.
  • the difference between the tension applied to the original film 10 between the original roll 11 and the nip roll disposed immediately before being immersed in the swelling bath and the tension applied after the nip roll is, for example, 10 N / m or more, preferably 50 N / m or more. That the tension of the original film 10 between the original roll 11 and the nip roll arranged immediately before being immersed in the swelling bath, and that the tension difference is within the above range, suppress the curling of the end of the original film 10. In addition to the above effect, it is also preferable from the viewpoint of suppressing the generation of wrinkles of the raw film 10.
  • the raw film 10 swells in the width direction and the film is wrinkled.
  • a roll having a widening function such as an expander roll, a spiral roll, or a crown roll is used for the guide rolls 30, 31 and / or 32, a cross guider, a bend bar. Or using other widening devices such as tenter clips.
  • Another means for suppressing the generation of wrinkles is to perform stretching.
  • the uniaxial stretching process can be performed in the swelling bath 13 by utilizing the peripheral speed difference between the nip roll 50 and the nip roll 51.
  • the film swells and expands in the film conveyance direction. Therefore, when the film is not actively stretched, for example, it is disposed before and after the swelling bath 13 in order to eliminate the sag of the film in the conveyance direction. It is preferable to take measures such as controlling the speed of the nip rolls 50 and 51.
  • the water flow in the swelling bath 13 is controlled by an underwater shower, or an EPC device (Edge Position Control device: detecting the edge of the film to meander the film. It is also useful to use a device for preventing the above in combination.
  • the film drawn from the swelling bath 13 passes through the guide roll 32 and the nip roll 51 in this order and is introduced into the dyeing bath 15.
  • the dyeing treatment is performed for the purpose of adsorbing and orienting the dichroic dye on the polyvinyl alcohol-based resin film after the swelling treatment.
  • the processing conditions are determined within a range in which the object can be achieved and in a range in which defects such as extreme dissolution and devitrification of the film do not occur.
  • the dyeing process is carried along a film carrying path constructed by guide rolls 33 to 35 and nip roll 51, and the film after swelling treatment is dyed in bath 15 (treatment liquid contained in a dyeing tank). ) For a predetermined time and then withdrawing.
  • the film subjected to the dyeing treatment step is preferably a film subjected to at least some uniaxial stretching treatment, or instead of the uniaxial stretching treatment before the dyeing treatment, Alternatively, in addition to the uniaxial stretching process before the dyeing process, it is preferable to perform the uniaxial stretching process during the dyeing process.
  • An aqueous solution can be used.
  • potassium iodide other iodides such as zinc iodide may be used, or potassium iodide and other iodides may be used in combination.
  • compounds other than iodide for example, boric acid, zinc chloride, cobalt chloride and the like may coexist. When boric acid is added, it is distinguished from the crosslinking treatment described later in terms of containing iodine.
  • the dyeing bath 15 Can be considered.
  • the temperature of the dyeing bath 15 when dipping the film is usually about 10 to 45 ° C., preferably 10 to 40 ° C., more preferably 20 to 35 ° C., and the dipping time of the film is usually 30 to 600 seconds. Degree, preferably 60 to 300 seconds.
  • a water-soluble dichroic dye for example, an aqueous solution having a concentration of dichroic dye / water by weight ratio of about 0.001 to 0.1 / 100 is used for the dyeing bath 15. be able to.
  • This dyeing bath 15 may contain a dyeing assistant or the like, and may contain, for example, an inorganic salt such as sodium sulfate or a surfactant. Only one dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.
  • the temperature of the dyeing bath 15 when dipping the film is, for example, about 20 to 80 ° C., preferably 30 to 70 ° C., and the dipping time of the film is usually about 30 to 600 seconds, preferably about 60 to 300 seconds. is there.
  • the film can be uniaxially stretched in the dyeing bath 15 in the dyeing process. Uniaxial stretching of the film can be performed by a method of making a peripheral speed difference between the nip roll 51 and the nip roll 52 arranged before and after the dyeing bath 15.
  • the widening function such as an expander roll, a spiral roll, or a crown roll is provided on the guide rolls 33, 34 and / or 35 in order to convey the polyvinyl alcohol resin film while removing the wrinkles of the film as in the swelling process.
  • Another means for suppressing the generation of wrinkles is to perform a stretching process as in the swelling process.
  • the film drawn from the dyeing bath 15 passes through the guide roll 35 and the nip roll 52 in this order and is introduced into the crosslinking bath 17.
  • the crosslinking treatment is a treatment performed for the purpose of water resistance and hue adjustment (for example, preventing the film from being bluish) by crosslinking.
  • the crosslinking treatment is carried along the film conveyance path constructed by the guide rolls 36 to 38 and the nip roll 52, and is subjected to the dyeing treatment in the crosslinking bath 17 (treatment liquid accommodated in the crosslinking tank). It can be carried out by immersing the film for a predetermined time and then withdrawing it.
  • the crosslinking bath 17 can be an aqueous solution containing, for example, about 1 to 10 parts by weight of boric acid with respect to 100 parts by weight of water.
  • the crosslinking bath 17 preferably contains iodide in addition to boric acid, and the amount is, for example, 1 to 30 weights per 100 weight parts of water.
  • iodide include potassium iodide and zinc iodide.
  • compounds other than iodide for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate and the like may coexist.
  • the concentration of boric acid and iodide and the temperature of the crosslinking bath 17 can be appropriately changed depending on the purpose.
  • the purpose of the crosslinking treatment is water resistance by crosslinking, and the polyvinyl alcohol resin film is subjected to swelling treatment, dyeing treatment and crosslinking treatment in this order
  • the temperature of the crosslinking bath when dipping the film is usually about 50 to 70 ° C., preferably 53 to 65 ° C., and the dipping time of the film is usually about 10 to 600 seconds, preferably 20 to 300 seconds, more preferably. Is 20 to 200 seconds.
  • the temperature of the crosslinking bath 17 is usually about 50 to 85 ° C., preferably 55 to 80 ° C. .
  • a crosslinking agent containing boric acid / iodide / water 1 to 5/3 to 30/100 in terms of weight ratio is contained. Liquid can be used.
  • the temperature of the crosslinking bath when dipping the film is usually about 10 to 45 ° C., and the dipping time of the film is usually about 1 to 300 seconds, preferably 2 to 100 seconds.
  • the cross-linking treatment may be performed a plurality of times, usually 2 to 5 times.
  • the composition and temperature of each crosslinking bath used may be the same or different as long as they are within the above range.
  • the cross-linking treatment for water resistance by cross-linking and the cross-linking treatment for hue adjustment may be performed in a plurality of steps, respectively.
  • the uniaxial stretching process can also be performed in the crosslinking bath 17 using the peripheral speed difference between the nip roll 52 and the nip roll 53.
  • a widening function such as an expander roll, a spiral roll, or a crown roll is provided on the guide rolls 36, 37 and / or 38 in order to convey the polyvinyl alcohol resin film while removing the wrinkles of the film as in the swelling treatment.
  • Can be used, or other widening devices such as cross guiders, bend bars, tenter clips can be used.
  • Another means for suppressing the generation of wrinkles is to perform a stretching process as in the swelling process.
  • the film drawn from the crosslinking bath 17 passes through the guide roll 38 and the nip roll 53 in this order and is introduced into the cleaning bath 19.
  • the production method of the present invention can include a washing treatment step after the crosslinking treatment step.
  • the washing treatment is performed for the purpose of removing excess chemicals such as boric acid and iodine adhering to the polyvinyl alcohol resin film.
  • the washing treatment can be performed, for example, by immersing the crosslinked polyvinyl alcohol resin film in the washing bath 19 (water), spraying the film with water as a shower, or using these together.
  • FIG. 1 shows an example in which a polyvinyl alcohol resin film is immersed in a cleaning bath 19 to perform a cleaning process.
  • the temperature of the washing bath 19 in the washing treatment is usually about 2 to 40 ° C., and the immersion time of the film is usually about 2 to 120 seconds.
  • a roll having a widening function such as an expander roll, a spiral roll, or a crown roll is used for the guide rolls 39, 40 and / or 41 for the purpose of conveying the polyvinyl alcohol resin film while removing wrinkles.
  • other widening devices such as cross guiders, bend bars, tenter clips can be used.
  • a stretching process may be performed in order to suppress generation of wrinkles.
  • the raw film 10 is uniaxially stretched wet or dry during the series of processing steps (that is, before and after any one or more processing steps and / or during any one or more processing steps). It is processed.
  • a specific method of the uniaxial stretching process is, for example, between rolls that perform longitudinal uniaxial stretching with a peripheral speed difference between two nip rolls (for example, two nip rolls arranged before and after the treatment bath) constituting the film conveyance path. Stretching, hot roll stretching as described in Japanese Patent No. 2731813, tenter stretching, and the like, and inter-roll stretching is preferred.
  • the uniaxial stretching treatment step can be performed a plurality of times before the polarizing film 23 is obtained from the raw film 10. As described above, the stretching treatment is also advantageous for suppressing the generation of wrinkles on the film.
  • the final cumulative draw ratio of the polarizing film 23 based on the original film 10 is usually about 4.5 to 7 times, preferably 5 to 6.5 times.
  • the stretching treatment step may be performed in any processing step, and when the stretching treatment is performed in two or more processing steps, the stretching treatment may be performed in any processing step. According to the present invention, even when the uniaxial stretching process is performed at any stage after the swelling process (including the swelling process), the film breakage during the stretching process can be effectively suppressed.
  • the drying of the film is not particularly limited, but can be performed using a drying furnace 21 as in the example shown in FIG.
  • the drying temperature is, for example, about 30 to 100 ° C.
  • the drying time is, for example, about 30 to 600 seconds.
  • the thickness of the polarizing film 23 obtained as described above is, for example, about 5 to 30 ⁇ m.
  • Processing other than the processing described above can also be added.
  • treatments that can be added include immersion treatment (complementary color treatment) in an aqueous iodide solution that does not contain boric acid, and immersion treatment in an aqueous solution that does not contain boric acid and contains zinc chloride, etc. (zinc) Processing).
  • a polarizing plate can be obtained by bonding a protective film via an adhesive on at least one surface of the polarizing film produced as described above.
  • a protective film for example, a film made of an acetyl cellulose resin such as triacetyl cellulose or diacetyl cellulose; a film made of a polyester resin such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate resin film; Examples include olefin-based resin films; (meth) acrylic-based resin films; and films made of polypropylene-based chain olefin-based resins.
  • (meth) acryl means at least one selected from acrylic and methacrylic.
  • an adhesive used for laminating a polarizing film and a protective film an active energy ray curable adhesive such as an ultraviolet curable adhesive, an aqueous solution of a polyvinyl alcohol resin, or an aqueous solution in which a crosslinking agent is blended.
  • water-based adhesives such as urethane emulsion adhesives.
  • the ultraviolet curable adhesive may be a mixture of a (meth) acrylic compound and a radical photopolymerization initiator, a mixture of an epoxy compound and a cationic photopolymerization initiator, or the like. Further, a cationic polymerizable epoxy compound and a radical polymerizable (meth) acrylic compound may be used in combination, and a photo cationic polymerization initiator and a photo radical polymerization initiator may be used in combination as an initiator.
  • the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
  • the curl angles at both ends in the width direction of the raw film 10 continuously immersed in the swelling bath 13 were measured by the following method.
  • Example 1 An apparatus similar to the polarizing film manufacturing apparatus shown in FIG. 1 except that two crosslinking baths 17 (hereinafter, the first crosslinking bath is referred to as 17a and the second crosslinking bath is referred to as 17b) are used.
  • 17a the first crosslinking bath
  • 17b the second crosslinking bath
  • All the guide rolls 30 to 41 were flat rolls.
  • the film after the second crosslinking treatment was immersed in a cleaning bath 19 containing pure water at 6 ° C., and then dried at 70 ° C. for 3 minutes by passing through a drying furnace 21 to produce a polarizing film 23. .
  • Example 2 Polarizing film production was carried out continuously for 24 hours in the same manner as in Example 1 except that the temperature in the unwinding step was 23 ° C. and the relative humidity was 40% RH. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 15 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 3 A polyvinyl alcohol film having a thickness of 30 ⁇ m (trade name “Kuraray Poval Film VF-PE # 3000” manufactured by Kuraray Co., Ltd., polymerization degree 2400, saponification degree 99.9 mol% or more) was used as a raw film.
  • the polarizing film was continuously manufactured for 24 hours. From the time the polyvinyl alcohol film was unwound from the raw fabric roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 60 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 4 A polarizing film was continuously produced for 24 hours in the same manner as in Example 3 except that the time for the unwinding step was 480 seconds. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 75 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 5 A polarizing film was continuously produced for 24 hours in the same manner as in Example 1 except that the time for the unwinding step was 600 seconds. From the time the polyvinyl alcohol film was unwound from the raw fabric roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 60 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 6> A polarizing film was continuously produced for 24 hours in the same manner as in Example 1 except that the time for the unwinding step was 720 seconds. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 75 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 7 A polarizing film was continuously produced for 24 hours in the same manner as in Example 3 except that the time for the unwinding step was 600 seconds. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 75 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 1 A polarizing film was produced in the same manner as in Example 3 except that the unwinding time was 720 seconds.
  • the curl angle at both ends in the film width direction when the polyvinyl alcohol film was immersed in the swelling bath 13 was 105 °.
  • the film was broken during the stretching treatment in the crosslinking treatment, and a polarizing film could not be obtained.
  • Example 8> Other than having blown hot air of 30 ° C. for 30 seconds from the surface opposite to the curled surface of the polyvinyl alcohol film after the polyvinyl alcohol film was unwound from the roll 11 and immersed in the swelling bath 13.
  • the polarizing film was continuously produced for 24 hours. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 75 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 9> Just as in Comparative Example 1, except that a metal bar for pressing both ends in the film width direction was installed immediately before the nip roll 50 in the unwinding step, and the widening process was performed on both ends in the width direction of the polyvinyl alcohol film. Then, the polarizing film was continuously manufactured for 24 hours. From the time the polyvinyl alcohol film was unwound from the raw fabric roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 60 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Example 10> A polarizing film was continuously produced for 24 hours in the same manner as in Example 3 except that the time for the unwinding step was 300 seconds. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 45 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.
  • Polarizing film production was carried out continuously for 24 hours in the same manner as in Example 3 except that the time for the unwinding step was 150 seconds. From the time the polyvinyl alcohol film was unwound from the raw roll 11 until it was immersed in the swelling bath 13, the curl angle at both ends in the film width direction was 45 ° or less. During operation for 24 hours, no film breakage occurred in any of the treatment steps, and no folding at both ends in the film width direction was observed.

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  • Physics & Mathematics (AREA)
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  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)
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PCT/JP2015/071223 2014-08-04 2015-07-27 偏光フィルムの製造方法 WO2016021432A1 (ja)

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JP2017211657A (ja) 2017-11-30
CN106575008A (zh) 2017-04-19
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TWI654225B (zh) 2019-03-21
KR20170040241A (ko) 2017-04-12
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