JP2013033154A - Process film manufacturing method and manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of processing a resin film into a process film of the resin film, which reduces occurrence of scratches, dents, etc. while satisfying characteristics required for the process film, and includes at least a process step of conveying a long length of the resin film while bringing the film into contact with a process liquid in a process tank.SOLUTION: The method of manufacturing a process film comprises a step of, after the process film obtained through a process step is conveyed from within a processing tank, conveying the process film via a nip roller formed of a first roller and a second roller, which are respectively located upstream and downstream with reference to the direction of conveying the process film, and via a guard roller positioned subsequently to the nip roller. The guard roller is an upper guard roller which is positioned such that the top part of the guard roller is higher than the top part of the second roller in the nip roller.

Description

  The present invention relates to a method for manufacturing a treated film of a resin film from a resin film and a manufacturing apparatus therefor. As a resin film, what is used in various field | areas can be suitably selected according to a process target. In particular, various processed films required to have no fine scratches on the processed film, for example, a polyvinyl alcohol film is used as a resin film in the production of a polarizer. The present invention can be applied in at least one processing step of a process, a dyeing process, a crosslinking process, a stretching process, and a washing process.

  In addition, as the resin film, various optical films such as a transparent protective film for a polarizer such as a cellulose ester-based resin are used, and at least one of the saponification step and the subsequent water washing step treatment, The invention can be applied. An optical film including a polarizer or the like can be used for an image display device such as a liquid crystal display device, an electroluminescence (EL) display device, a plasma display (PD), and a field emission display (FED).

  An optical film such as a polarizer is used for an image display device (particularly, a liquid crystal display device). Usually, the polarizer is produced by dyeing and uniaxially stretching a polyvinyl alcohol (PVA) film. When the PVA-based film is uniaxially stretched, the dichroic material adsorbed (stained) on the PVA molecules is oriented, so that a polarizer is obtained.

  Many methods have been proposed so far to obtain such a polarizer. For example, as a method for producing a polarizer, after an unoriented PVA film is swollen in a swelling bath, iodine or a dichroic dye is adsorbed, and further, treatment such as crosslinking and stretching is performed in an aqueous solution containing boric acid. It has been proposed (Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 10-153709 JP 2004-341515 A

  In recent years, liquid crystal display devices have been improved in performance, and high visibility has been demanded. Accordingly, it is very important that the polarizing plate also has high visibility and good visibility. Therefore, about a polarizing plate, it is calculated | required that visibility is not inhibited about any of a polarizer and its transparent protective film. In addition, if the polarizing plate has scratches or dents (scratches of dots), it is not preferable in that the product is inferior in product inspection and the yield of the product is reduced. A polarizing plate is a laminate of a polarizer and a transparent protective film. Usually, the polarizer and the transparent protective film are bonded together with an adhesive or the like. If there is a mark, the adhesion between the layers due to the adhesive or the like becomes poor.

  One reason for the decrease in visibility in the polarizing plate is the generation of scratches and dents in the polarizer and its transparent protective film. As described above, the polarizer is manufactured by immersing and transporting a PVA film or the like in a staining solution, while the transparent protective film is transported in a saponification treatment or a water washing treatment bath before being bonded to the polarizer. . Usually, when these treatments are performed, there is a tendency that the scratches and dents generated in these increase as the production speed increases. Further, in the manufacture of a polarizer, there is a problem that nicks (knic defects) occur. A knick is a local irregularity defect that occurs when the surface of a PVA film comes into contact with a roll and rubs.

  The present invention is a method for producing a treated film of a resin film from the resin film, comprising at least a treatment step of conveying a long resin film while being brought into contact with a treatment liquid in a treatment tank. It aims at providing the manufacturing method and manufacturing apparatus of a processing film which can reduce the generation | occurrence | production of a scratch, a dent, etc., satisfying the characteristic requested | required of a processing film.

  Furthermore, it aims at providing the manufacturing method and manufacturing apparatus of the process film which can reduce generation | occurrence | production of a scratch, a dent, etc., and can reduce a nick.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the object can be achieved by the following process film production method and production apparatus, and have completed the present invention.

That is, the present invention is a method for producing a treated film of a resin film from the resin film, comprising at least a treatment step of conveying a long resin film while being brought into contact with a treatment liquid in a treatment tank.
At least one of the processing steps includes a first roll and a second roll (on the upstream side based on the transport direction of the processing film, after the processing film obtained by the processing step is unloaded from the processing tank. A nip roll comprising a roll and a downstream side as a second roll) and a guard roll disposed following the nip roll; and
The said guide roll is related with the manufacturing method of the processing film characterized by the top part of the said guide roll being the upper guide roll arrange | positioned above the top part of the 2nd roll in the said nip roll.

  In the process film manufacturing method, the upper guide roll may be provided with a liquid supply means to the surface of the upper guide roll.

  In the method for producing the treated film, the nip roll and the upper guide roll have a direction of an imaginary perpendicular to an imaginary line connecting the center points of the first roll and the second roll of the nip roll set to 0 °, It is preferable that the angle formed by the virtual transport line representing the direction of the processing film transported by the nip roll and the upper guide roll is arranged to be 0 to less than 90 °.

  In the method for producing a treated film, the treatment tank is provided with another nip roll for carrying the resin film into the treatment tank with respect to the nip roll for carrying out the treated film, and the peripheral speed difference between these nip rolls. Thereby, it can carry out, extending | stretching a elongate resin film to a longitudinal direction.

  The manufacturing method of the said processing film can be applied suitably, when the processing film obtained by giving a processing process to the said resin film is an optical film.

  The manufacturing method of the said processing film can be applied when the said resin film is a polyvinyl alcohol-type film and manufacturing the polarizer which is a processing film. In this case, the treatment process includes at least a swelling process, a dyeing process, a crosslinking process, a stretching process, and a washing process, and in any one of the swelling process, the dyeing process, the crosslinking process, the stretching process, and the washing process. Then, after carrying out the obtained treated film from the inside of the treatment tank, it has a step of conveying it through the nip roll and an upper guard roll arranged following the nip roll.

Moreover, this invention is equipped with the at least 1 process tank with which the process liquid for performing arbitrary processes to a resin film is equipped,
The processing tank includes a first roll and a second roll (on the basis of the transport direction of the processing film, the first side for transporting the processing film processed in the processing tank after unloading it from the processing tank. And a guard roll disposed subsequent to the nip roll, and the top of the guide roll is a second roll in the nip roll. It is related with the manufacturing apparatus of the process film characterized by being an upper guide roll arrange | positioned upwards from the top part.

  The said manufacturing apparatus can have a liquid supply means to the surface of the said upper guide roll.

  In the manufacturing apparatus, the nip roll and the upper guide roll have a direction of a virtual perpendicular to a virtual line connecting the center points of the first roll and the second roll of the nip roll set to 0 °, and the virtual perpendicular, the nip roll, and the It is preferable that the angle formed by the virtual transport line representing the direction of the processing film transported by the upper guide roll is arranged to be less than 0 to 90 °.

  The said manufacturing apparatus WHEREIN: The nip roll which carries the said resin film in the said processing tank can be arrange | positioned at the said processing tank with respect to the nip roll which carries out the said processing film.

  Usually, the processing film obtained by performing the processing process which makes a processing liquid contact the resin film (for example, PVA-type film) conveyed continuously is carried out by the nip roll after being carried out from the inside of the processing tank which has a processing liquid. It is conveyed while being drained. Scratches and dents occur in the treated film because fine foreign matter enters with the fluid (treatment liquid) between the treated film and the nip roll, and the foreign matter is sandwiched between the nip rolls. It is thought to occur.

  In the manufacturing method of this invention, the upper guide roll installed above the said nip roll is provided next to the said nip roll. The top part of the upper guide roll is disposed above the top part of the second roll on the downstream side of the nip roll. In this way, by providing the nip roll and then the upper guide roll, the processed film that is transported between the nip rolls does not substantially contact the nip roll after passing between the nip rolls. Led. Therefore, it is considered that scratches and dents that are generated when foreign matter is caught between nip rolls can be suppressed.

  Moreover, in the manufacturing method of this invention, the processed film conveyed through a nip roll hardly contacts a nip roll after passing between nip rolls. Therefore, it is considered that the nick generated by the surface of the treated film that has been drained coming into contact with the nip roll and being rubbed can be suppressed. On the other hand, the processed film that has passed through the nip roll is conveyed by the upper guide roll. However, if the upper guide roll is dry, there is a risk that a nick will occur due to rubbing with the processed film. In the production method of the present invention, a thin liquid film can be formed on the surface of the upper guide roll by providing a liquid supply means to the surface of the upper guide roll. As a result, it is considered that the dry state of the treated film can be improved and nicks can be more effectively suppressed.

  According to the production method of the present invention, a treated film (optical film such as a polarizer) excellent in in-plane optical characteristics can be produced from a PVA film which is a resin film.

It is a conceptual diagram which shows one Embodiment which concerns on the process process in the manufacturing method of the process film of this invention. It is a conceptual diagram which shows one form of the angle regarding arrangement | positioning of the nip roll which concerns on a process process, and an upper guide roll in the manufacturing method of the process film of this invention. It is a conceptual diagram which shows one Embodiment concerning the manufacturing method of a polarizer concerning the manufacturing method of the process film of this invention. It is a conceptual diagram which shows the manufacturing method of a polarizer regarding the manufacturing method of the conventional process film.

  The method for producing a treated film of the present invention will be described below with reference to the drawings. FIG. 1 relates to a treatment process in the method for producing a treated film of the present invention. In FIG. 1, the resin film W and a pair of first roll R1 and second roll R2 arranged in the horizontal direction (the first roll R1 on the upstream side and the second roll R2 on the downstream side based on the transport direction of the treated film). 1), an upper guide roll G, and a processing tank Y having a processing liquid X are shown. The processing film W ′ carried out from the processing tank Y is drained by the nip rolls R1 and R2. In FIG. 1, the resin film W carried into the treatment tank Y is conveyed through the treatment liquid X via two guide rolls g. The number and arrangement of the guide rolls g in the treatment liquid X can be determined as appropriate. The arrangement relationship between the final guide roll g and the nip rolls R1 and R2 in the processing liquid X is not particularly limited, but the processing liquid X and foreign matters scraped off from the surface of the processing film W ′ by the drainage can be smoothly removed. From the viewpoint of dropping, as shown in FIG. 1, it is preferable to arrange the final guide roll g so that the processing film carried out from the final guide roll g is conveyed in the vertical direction toward the nip rolls R1 and R2. .

  As shown in FIG. 1, the first roll R1 and the second roll R2 related to the nip roll are preferably arranged in the horizontal direction in order to drain the processing liquid X and foreign matters from the surface of the processing film W ′. As shown in FIG. 1, by arranging the nip rolls R1 and R2 in the horizontal direction, the processing film passes through the nip rolls R1 and R2 in the vertical direction. The absolute amount of foreign matter sandwiched between the nip rolls R1 and R2 can be reduced.

  On the other hand, the 1st roll R1 and 2nd roll R2 which concern on a nip roll may be arrange | positioned in a non-horizontal direction so that any one roll may become a position higher than the other roll. When the first roll R1 and the second roll R2 are arranged in the non-horizontal direction, it is usually preferable that the first roll R1 is arranged at a position higher than the second roll R2. The first roll R1 and the second roll R2 can also be arranged in the vertical direction. When the first roll R1 and the second roll R2 are arranged in the vertical direction, the lower roll corresponds to the second roll R2. Even when the first roll R1 and the second roll R2 are arranged in the non-horizontal direction, as shown in FIG. 1, the processed film carried out from the final guide roll g is conveyed in the vertical direction toward the nip rolls R1 and R2. It is preferable to arrange the final guide roll g as described above.

  The upper guide roll G is provided following the nip rolls R1 and R2. Further, the top b of the upper guide roll G is disposed above the top a of the second roll R2 in the nip rolls R1 and R2. Thus, by arranging the upper guide roll G with respect to the second roll R2, the contact between the processing film W ′ that has passed through the nip rolls R1 and R2 and the nip rolls R1 and R2 can be reduced.

  If the top part b of the upper guide roll G is arrange | positioned above the top part a of the 2nd roll R2 in the said nip roll R1, R2, there will be no restriction | limiting in particular. In FIG. 1, the upper guide roll G is installed substantially above the second roll R2. With reference to the case where the flow direction of the processing steps of the entire apparatus is from the left side to the right side as shown in FIG. 1, the installation of the upper guide roll G may be arranged on the left side of the second roll R2, It may be arranged on the right side of the first roll R1. From the viewpoint of productivity, the upper guide roll G is preferably disposed in the vertical direction or on the right side of the second roll R2.

  In the upper guide roll G, the top b of the guide roll G is preferably arranged above the top a of the second roll R2 in the nip rolls R1 and R2, but the bottom c of the guide roll G is It does not need to be arranged above the top a of the two rolls R2. However, it is preferable that the bottom c of the guide roll G is disposed above the top a of the second roll R2.

  FIG. 2 is an example showing a preferred embodiment regarding the arrangement of the nip rolls R1 and R2 and the upper guide roll G. As shown in FIG. 2, the upper guide roll G is preferably arranged in the vertical direction or downstream of the second roll R2. Specifically, the direction of the virtual perpendicular v2 with respect to the virtual line v1 connecting the center points s1 and s2 of the first roll R1 and the second roll R2 related to the nip rolls R1 and R2 is 0 °, and the virtual perpendicular v2 and the nip roll It is preferable that the angle A formed by the virtual transport line v3 representing the direction of the processing film W ′ transported by the upper guide roll G is 0 to less than 90 °. The angle A is preferably as small as possible, preferably 75 ° or less, more preferably 60 ° or less, further preferably 30 ° or less, and most preferably 0 °. In FIG. 2, the upper guide roll G1 is disposed when the angle A is 0 °, the upper guide roll G2 is disposed when the angle A is 30 °, and the upper guide roll G3 is disposed when the angle A is 60 °. The arrangement of the guide roll G4 when the angle A is 75 ° is shown.

  In FIG. 1, liquid supply means Q is provided on the upper guide roll G. By supplying various liquids to the surface of the upper guide roll G by the liquid supply means Q, a thin liquid film can be efficiently formed on the surface of the upper guide roll G, and a nick generated on the processing film W ′ is efficiently produced. Can be suppressed. The liquid supply means Q is not particularly limited, and examples thereof include a liquid tray, a dust-free felt, and a nozzle. Various liquids can be supplied by the liquid supply means Q. Examples of the liquid include water and a processing liquid similar to that used in each processing tank.

  In FIG. 1, nip rolls R <b> 1 and R <b> 2 for carrying the resin film W into the processing tank Y are disposed in the processing tank Y in correspondence with the nip rolls R <b> 1 and R <b> 2 for carrying out the processing film W ′ from the processing tank Y. it can. In FIG. 1, the nip rolls carried into the treatment tank Y are not shown. As described above, when the nip rolls R1 and R2 for carrying the resin film and the nip rolls R1 and R2 for carrying the treatment film are arranged in the treatment tank Y, the resin film W is moved in the longitudinal direction due to a difference in peripheral speed between them. This can be done while stretching. Normally, when stretching is performed in the processing step, the peripheral speed of the nip rolls R1 and R2 installed at the rear is faster than the peripheral speed of the nip rolls R1 and R2 disposed in the front in the running direction of the resin film W. The difference in peripheral speed between the nip rolls R1 and R2 is controlled.

  Although not shown in FIG. 1, liquid draining means for one side or both sides of the treated film W ′ can be provided before and after the nip rolls R <b> 1 and R <b> 2. Examples of the liquid draining means include a liquid draining roller, a liquid draining bar, a scraper, and an air knife. In particular, a rotary liquid draining roller and a non-contact type air knife are preferable. The arrangement of the liquid draining means is preferably before the treated film ′ comes into contact with the nip rolls R1 and R2 in order to suppress the generation of scratches and dents.

  The transport speed (mm / min) of the resin film W is usually preferably in the range of 0.1 to 30 m / min, and more preferably in the range of 1 to 15 mm / min. By making a conveyance speed 0.1 mm / min or more, productivity of processing film W '(for example, polarizer) from the resin film W can be improved. On the other hand, by setting the transport speed to 30 m / min or less, it is possible to reduce the convection of the processing liquid X due to shearing.

  The treatment tank Y is filled with a treatment liquid (details will be described later) for performing an arbitrary treatment on the resin film W. The resin film W can be contacted by being immersed in the treatment liquid X. The resin film W is processed with the processing liquid X to obtain a processed film W ′.

  Further, the viscosity of the treatment liquid X is preferably 100 mPa · s or less, more preferably 50 mPa · s or less, and still more preferably 10 mPa · s or less. By setting the viscosity of the treatment liquid X to 100 mPa · s or less, friction between the resin film W and the treatment liquid can be reduced. As a result, the flow of the processing liquid generated due to the conveyance of the resin film W in contact with the processing liquid X can be suppressed, and the occurrence of processing unevenness can be reduced.

  Various resin materials can be used as the resin film used in the method for producing a treated film of the present invention. The resin material is appropriately selected and used according to various uses. As the resin material, a material having translucency in the visible light region can be suitably used in applications such as an optical film.

  Examples of the translucent resin include translucent water-soluble resins. As for the resin film using a translucent water-soluble resin, for example, a PVA film is suitably used for manufacturing a polarizer. Polyvinyl alcohol or a derivative thereof is used for the PVA film. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. can give. The degree of polymerization of polyvinyl alcohol is preferably about 100 to 10,000, and more preferably 1,000 to 10,000. A saponification degree of about 80 to 100 mol% is generally used.

  In addition to the above, PVA films include hydrophilic polymer films such as ethylene / vinyl acetate copolymer partially saponified films, polyene-based oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products, etc. Is mentioned.

  The PVA film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol film.

  Examples of the translucent water-soluble resin include polyvinyl pyrrolidone resins and amylose resins.

  The thickness of the resin film W can be appropriately determined according to the application. As for the thickness of the resin film W, the thing about 10-300 micrometers is used normally, Preferably it is 20-100 micrometers. The film width of the resin film W is preferably in the range of 100 to 4000 mm, and more preferably in the range of 500 to 3500 mm.

  When the resin film W is, for example, a PVA film used for manufacturing a polarizer, the thickness thereof is preferably in the range of 15 to 110 μm, more preferably in the range of 38 to 110 μm, and 50 to 100 μm. Within the range is more preferable, and within the range of 60 to 80 μm is particularly preferable. When the thickness of the PVA-based film is less than 15 μm, the mechanical strength of the PVA-based film is too low to make uniform stretching difficult, and color spots are likely to occur when a polarizer is manufactured. On the other hand, if the thickness of the PVA-based film exceeds 110 μm, sufficient swelling cannot be obtained, and color spots of the polarizer are easily emphasized, which is not preferable.

  About the one aspect | mode of implementation of the manufacturing method of the process film of this invention, the case where an optical film is obtained by giving a process process to a resin film is demonstrated below, referring drawings. FIG. 3 is a conceptual diagram showing an example of a method for producing a polarizer, according to the method for producing a treated film of the present invention. The method for producing a polarizer includes a swelling process A, a dyeing process B, a crosslinking process C, a stretching process D, and a cleaning process E. In FIG. 3, a swelling process A, a dyeing process B, a crosslinking process C, a stretching process D, and a cleaning process E are sequentially performed on the resin film (PVA-based film) W fed out from the raw fabric roll in order, and finally This is a case where a polarizer is manufactured in which the drying step F is performed.

  In FIG. 3, the resin film W is conveyed from the feed roll R through the nip rolls R <b> 1 and R <b> 2 arranged in each processing tank Y. Behind the drying step F, there is a winding roll R ′ for the processing film W ′. After the resin film W is processed in each processing tank Y, it is carried out as a processing film. The nip rolls R1 and R2 are arranged in the horizontal direction in the upper part of the rear part of each processing tank Y. Nip rolls R1 and R2 are arranged in the vertical direction above the front part of the expansion step A. Further, an upper guide roll G is disposed above the nip rolls R1 and R2 disposed in each processing tank Y (excluding the processing tank Y in the cleaning step E). In FIG. 3, the nip rolls R1 and R2 disposed between the swelling process A and the dyeing process B, the dyeing process B and the crosslinking process C, the crosslinking process C and the stretching process D, and the stretching process D and the cleaning process E are It serves as a rear nip roll and a front nip roll.

  In FIG. 3, a treatment liquid X corresponding to each process is used in each treatment tank Y in the swelling process A, the dyeing process B, the crosslinking process C, the stretching process D, and the cleaning process E. In FIG. 3, although the upper guide roll G is arrange | positioned with respect to the nip roll R1, R2, as a process process in each process tank Y which concerns on the swelling process A, the dyeing process B, the bridge | crosslinking process C, and the extending process D, this The arrangement | positioning of nip roll R1, R2 of this invention and the upper guide roll G should just be performed in the process process in any at least 1 process tank Y. FIG. Therefore, the processing step for arranging the nip rolls R1 and R2 and the upper guide roll G according to the method for manufacturing the processed film of the present invention includes a swelling step A, a dyeing step B, a crosslinking step C, a stretching step D, and a cleaning step E. In the method for producing a polarizer, it may be applied in any step, or may be applied in two or more steps, or in all steps. In FIG. 3, the nip rolls R <b> 1 and R <b> 2 and the upper guide roll G are disposed at substantially the same angle and height in each processing tank Y, but the upper guide roll G is disposed in each processing tank Y. Can be designed accordingly.

  In addition, FIG. 4 is a conceptual diagram which shows the manufacturing method of a polarizer regarding the manufacturing method of the conventional process film. FIG. 4 shows that the nip rolls R1 and R2 are arranged behind the treatment tanks Y in the swelling process A, the dyeing process B, the crosslinking process C, the stretching process D, and the cleaning process E in FIG. This is a case where G is not arranged.

  The swelling step A is a step of bringing a PVA film as a raw fabric film into contact with a swelling liquid (treatment liquid). By performing this step, the PVA-based film is washed with water, and the surface of the PVA-based film can be cleaned of stains and anti-blocking agents, and the PVA-based film is swollen to prevent unevenness such as uneven coloring. It becomes possible.

  As the swelling liquid, for example, water can be used. Furthermore, you may add glycerol, potassium iodide, etc. in a swelling liquid suitably. The concentration to be added is preferably 5% by weight or less for glycerin and 10% by weight or less for potassium iodide. The temperature of the swelling liquid is preferably in the range of 20 to 45 ° C, more preferably in the range of 25 to 40 ° C, and still more preferably in the range of 30 to 35 ° C. Moreover, although the contact time with a swelling liquid is not specifically limited, Usually, it is preferable that it is 20 to 300 seconds, it is more preferable that it is 30 to 200 seconds, and it is especially preferable that it is 30 to 120 seconds.

  In the swelling step A, it can be appropriately stretched. The draw ratio is usually 6.5 times or less with respect to the original length of the PVA film. Preferably, from the viewpoint of optical properties, the draw ratio is preferably 1.2 to 6.5 times, more preferably 2 to 6.3 times, and even more preferably 3 to 6.1 times. In the swelling process A, by performing stretching, the stretching in the stretching process D applied after the swelling process A can be controlled to be small and can be controlled so as not to cause stretching of the film. On the other hand, when the stretching ratio in the swelling process A is increased, the stretching ratio in the stretching process is too small. In particular, when the stretching process D is performed after the crosslinking process C, it is not preferable in terms of optical characteristics.

  The dyeing step B is a step of adsorbing the iodine or dichroic dye to the PVA film by bringing the PVA film into contact with a dyeing liquid (treatment liquid) containing iodine or a dichroic dye. The dyeing process B can be performed together with the stretching process D.

  As the staining solution, a solution in which iodine is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent compatible with water may be further added. The concentration of iodine is preferably in the range of 0.01 to 10% by weight, more preferably in the range of 0.02 to 7% by weight, and particularly preferably 0.025 to 5% by weight. . In order to further improve the dyeing efficiency, it is preferable to further add iodide. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.010 to 10% by weight and more preferably 0.10 to 5% by weight in the dyeing bath. Among these, it is preferable to add potassium iodide, and the ratio (weight ratio) of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, and 1: 6 to 1:80. More preferably, it is in the range of 1: 7 to 1:70.

  The contact time with the staining solution is not particularly limited, but is usually preferably within a range of 10 to 200 seconds, more preferably within a range of 15 to 150 seconds, and even more preferably within a range of 20 to 130 seconds. Further, the temperature of the staining solution is preferably in the range of 5 to 42 ° C, more preferably in the range of 10 to 35 ° C, and still more preferably in the range of 12 to 30 ° C.

  The crosslinking step C is, for example, a step of bringing a PVA film into contact with a crosslinking solution (treatment solution) containing a crosslinking agent for crosslinking. The order of the crosslinking step C is not particularly limited. The crosslinking step C can be performed together with the stretching step D. The crosslinking step C can be performed a plurality of times. A conventionally known substance can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination of two or more.

  As the crosslinking liquid, a solution obtained by dissolving the crosslinking agent in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. The concentration of the crosslinking agent in the solution is not particularly limited, but is preferably in the range of 1 to 10% by weight, and more preferably in the range of 2 to 6% by weight.

  Iodide may be added to the cross-linking liquid from the viewpoint that uniform optical characteristics can be obtained in the plane of the polarizer. The iodide is not particularly limited, and examples thereof include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, and iodide. Examples thereof include tin and titanium iodide. Further, the iodide content is preferably in the range of 0.05 to 15% by weight, and more preferably in the range of 0.5 to 8% by weight. The iodide illustrated above may be used individually by 1 type, or may use 2 or more types together. When using 2 or more types together, the combination of boric acid and potassium iodide is preferable. The ratio (weight ratio) of boric acid and potassium iodide is preferably in the range of 1: 0.1 to 1: 3.5, and in the range of 1: 0.5 to 1: 2.5. Is more preferable.

  The temperature of the crosslinking liquid is not particularly limited, but is usually preferably in the range of 20 to 70 ° C, more preferably in the range of 20 to 40 ° C. The contact time with the PVA film is not particularly limited, but is usually preferably in the range of 5 to 400 seconds, more preferably in the range of 50 to 300 seconds, and still more preferably in the range of 150 to 250 seconds.

  The said extending | stretching process D is normally performed by giving uniaxial stretching. This stretching method can be performed together with the dyeing process B and the crosslinking process C. Uniaxial stretching can be performed by utilizing the difference in the peripheral speed of the nip rolls arranged at the front and rear of the treatment tank Y as described above. The stretching is generally performed, for example, after the dyeing step B is performed. In addition, stretching can be performed together with the crosslinking step C.

  In the stretching step D, the total stretching ratio is set to a range of 2 to 6.5 times in terms of the total stretching ratio with respect to the original length of the PVA film. Preferably it is 2.5 to 6.3 times, more preferably 3 to 6.1 times. That is, the total draw ratio refers to a cumulative draw ratio including stretching in those steps when stretching is involved in the later-described swelling step A other than the stretching step D. The total draw ratio is appropriately determined in consideration of the draw ratio in the swelling step A and the like. When the total draw ratio is low, the orientation is insufficient and it is difficult to obtain a polarizer having high optical properties (polarization degree). On the other hand, if the total draw ratio is too high, stretch breakage is likely to occur, and the polarizer becomes too thin, which may reduce the workability in the subsequent process.

  The treatment liquid used in the stretching step D can contain an iodide compound. When the treatment solution contains an iodide compound, the iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight.

  Although the temperature of the said processing bath is not specifically limited, Usually, the inside of the range of 20-70 degreeC is preferable, and the inside of the range of 20-40 degreeC is more preferable. The contact time with the PVA film is not particularly limited, but is usually preferably within a range of 5 to 100 seconds, more preferably within a range of 10 to 80 seconds, and still more preferably within a range of 20 to 70 seconds.

  In the manufacturing method of a polarizer, after performing the above-mentioned process, cleaning process E is performed. The cleaning step E can be performed with an iodide-containing aqueous solution (treatment liquid). As the iodide in the iodide-containing aqueous solution, those described above can be used, and among them, for example, potassium iodide and sodium iodide are preferable. With this iodide-containing aqueous solution, the remaining boric acid used in the crosslinking step can be washed away from the PVA film. When the aqueous solution is an aqueous potassium iodide solution, the concentration thereof is preferably in the range of 0.5 to 20% by weight, more preferably in the range of 1 to 15% by weight, and 1.5 to 7% by weight. Within the range is more preferable.

  Although the temperature of the said iodide containing aqueous solution is not specifically limited, Usually, the inside of the range of 15-40 degreeC is preferable, and the inside of the range which is 20-35 degreeC is more preferable. Moreover, although the contact time with a PVA-type film is not specifically limited, Usually, the inside of the range for 2 to 30 seconds is preferable, and the inside of the range for 3 to 20 seconds is more preferable.

  In addition, in the swelling process A, the dyeing process B, the crosslinking process C, the stretching process D, and the cleaning process E according to the manufacturing method of the polarizer, when the processing process of the present invention is not applied, the PVA film and the processing liquid Are processed by various contact methods. Examples of other contact methods include a method of immersing in a treatment liquid, a method of applying, and a method of spraying. The immersion time in the case of these methods and the temperature of the bath liquid can be appropriately set as necessary.

  After performing each said process, a drying process is finally given and a polarizer is manufactured. As the drying step, an appropriate method such as natural drying, air drying, heat drying or the like can be used, but heat drying is usually preferably used. When performing heat drying, although heating temperature is not specifically limited, Usually, the inside of the range of 25-80 degreeC is preferable, The inside of the range of 30-70 degreeC is more preferable, The inside of the range of 30-60 degreeC is still more preferable. The drying time is preferably about 1 to 10 minutes.

  The obtained polarizer can be made into the polarizing plate which provided the transparent protective film in the at least single side | surface according to the conventional method. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, Examples thereof include cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the present invention is not limited to the materials, blending amounts, and the like described in the examples unless otherwise specified.

Example 1
<Preparation of PVA film>
A raw fabric PVA film (manufactured by Kuraray Co., Ltd., trade name: VF-PS750) was prepared. This PVA film had a width of 3100 mm and a thickness of 75 μm.

<Production of polarizer>
Using the manufacturing apparatus of the present invention shown in FIG. 3, a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process were sequentially performed. More details are as follows. In addition, each processing tank used in each process of a swelling process, a dyeing process, a bridge | crosslinking and extending | stretching process, and a washing | cleaning process was installed horizontally. The conveyance speed of the PVA film was set to 12 m / min. Nip rolls R1 and R2 and an upper guide roll G shown in FIG. 2 are formed by virtual vertical lines v2 and virtual transport lines v3 in the upper part of the rear part of each treatment tank in the swelling process, dyeing process, crosslinking process and stretching process. The angle A was set to 0 °. Further, the final guide roll g was arranged so that the processing film carried out from the final guide roll g of each processing tank Y was conveyed in the vertical direction toward the nip rolls R1 and R2. Each upper guide roll G is provided with a liquid tray as a liquid supply means.

≪Swelling process≫
The treatment tank was filled with a swelling liquid (water, liquid temperature 30 ° C.). The contact time between the swelling liquid and the PVA film was 30 seconds, and the swelling was performed while stretching in the longitudinal direction. The stretching ratio in the machine direction was 2.4 times that of the unstretched PVA film.

≪Dyeing process≫
The treatment tank was filled with a staining solution (0.035 wt% iodine aqueous solution (containing 0.07 wt% potassium iodide), liquid temperature 25 ° C.). Further, the contact time between the dyeing solution and the PVA film was 30 seconds, and dyeing was performed while stretching in the longitudinal direction. The draw ratio in the machine direction was 3.3 times that of the unstretched PVA film.

≪Crosslinking process≫
The treatment tank was filled with a crosslinking liquid (an aqueous solution containing 2.5% by weight boric acid and 2% by weight potassium iodide, liquid temperature of 35 ° C.). The contact time between the crosslinking liquid and the PVA film was 60 seconds, and dyeing was performed while stretching in the longitudinal direction. The draw ratio in the machine direction was 3.5 times that of the unstretched PVA film.

≪Stretching process≫
The treatment tank was filled with a crosslinking liquid (an aqueous solution containing 2.5 wt% boric acid and 2 wt% potassium iodide, liquid temperature 60 ° C.). The contact time between the crosslinking liquid and the PVA film was 60 seconds, and dyeing was performed while stretching in the longitudinal direction. The draw ratio in the machine direction was 6.55 times that of the unstretched PVA film.

≪Cleaning process≫
The treatment tank was filled with the adjusting liquid (2.5 wt% hydrogen iodide aqueous solution, liquid temperature 30 ° C.). The contact time between the adjustment liquid and the PVA film was 15 seconds.

≪Drying process≫
The PVA film after the washing process was performed at a drying temperature of 40 ° C. and a drying time of 200 seconds. Thereafter, both ends of the PVA film were cut and wound up with polyethylene terephthalate as interleaving paper. This produced the roll-shaped polarizer. The thickness of the obtained polarizer was 30 μm.

<Preparation of polarizing plate>
A polarizing plate uses a laminator, and a triacetyl cellulose film (Fuji Film Co., Ltd., trade name: TD80UL) is bonded to both sides of the polarizer by PVA-based adhesion (Nippon Synthetic Chemical Co., Ltd., trade name: NH18). Pasted together. The bonding temperature was 25 ° C. Next, the laminated body after pasting was dried under conditions of 55 ° C. and 300 seconds using an air circulation type constant temperature oven. This produced the polarizing plate.

Comparative Example 1
<Production of polarizer>
The same raw fabric PVA film as in Example 1 was used. Using the manufacturing apparatus shown in FIG. 4, a swelling process, a dyeing process, a crosslinking / stretching process, a washing process, and a drying process were sequentially performed. The conveyance speed of the PVA film was set to 12 m / min.

<Preparation of polarizing plate>
The polarizing plate according to Comparative Example 1 was produced in the same manner as in Example 1.

  The polarizing plates obtained in Examples and Comparative Examples were cut out by 30 m and evaluated as follows. The results are shown in Table 1.

(Confirmation of foreign matter)
About the polarizing plate of each sample, the number of the presence or absence of a crack (bright spot) 200 micrometers or more was confirmed visually.

(Knic defect)
The polarizing plate of each sample was placed under a fluorescent lamp. Another polarizing plate was installed on the light source side of the polarizing plate of the sample so that the respective absorption axes were perpendicular to each other, and in this state, the number of points through which light was lost (knic defects) was counted.

  As can be seen from Table 1, it was confirmed that the polarizers according to the examples have few scratches on the film and can reduce nicks.

R1, R2 Nip roll G Upper guide roll X Treatment liquid Y Treatment tank W Resin film Q Liquid supply means

Claims (10)

In the method for producing a treated film of the resin film from the resin film, which has at least a treatment step of conveying the elongated resin film while being brought into contact with the treatment liquid in the treatment tank.
At least one of the processing steps includes a first roll and a second roll (on the upstream side based on the transport direction of the processing film, after the processing film obtained by the processing step is unloaded from the processing tank. A nip roll comprising a roll and a downstream side as a second roll) and a guard roll disposed following the nip roll; and
The said guide roll is a manufacturing method of the processed film characterized by the top part of the said guide roll being the upper guide roll arrange | positioned above the top part of the 2nd roll in the said nip roll.   The process for producing a treated film according to claim 1, wherein the upper guide roll is provided with means for supplying a liquid to the surface of the upper guide roll.   The nip roll and the upper guide roll are transported by the virtual perpendicular, the nip roll, and the upper guide roll with the direction of the virtual perpendicular to the virtual line connecting the center points of the first roll and the second roll of the nip roll being 0 °. The method for producing a treated film according to claim 1 or 2, wherein an angle formed by a virtual transport line representing a direction of the treated film is arranged to be less than 0 to less than 90 °.   For the nip roll for carrying out the treated film, another nip roll for carrying the resin film into the treatment tank is arranged in the treatment tank. Due to the difference in peripheral speed between these nip rolls, a long resin film is provided. The process for producing a treated film according to any one of claims 1 to 3, wherein the treatment is performed while stretching in the longitudinal direction.   The method for producing a treated film according to any one of claims 1 to 4, wherein the treated film obtained by subjecting the resin film to a treatment step is an optical film. The resin film is a polyvinyl alcohol film,
The treatment step includes at least a swelling step, a dyeing step, a crosslinking step, a stretching step, and a washing step, and in any one of the swelling step, the dyeing step, the crosslinking step, the stretching step, and the washing step, After carrying out the obtained treated film from the inside of the treatment tank, it has a step of conveying it through the nip roll and an upper guard roll arranged following the nip roll,
6. A method for producing a treated film according to claim 5, wherein a polarizer which is a treated film is produced. Including at least one treatment tank that fills a treatment liquid for performing any treatment on the resin film;
The processing tank includes a first roll and a second roll (on the basis of the transport direction of the processing film, the first side for transporting the processing film processed in the processing tank after unloading it from the processing tank. And a guard roll disposed subsequent to the nip roll, and the top of the guide roll is a second roll in the nip roll. An apparatus for producing a treated film, which is an upper guide roll disposed above the top of the processing film.   The manufacturing apparatus according to claim 7, wherein the upper guide roll is provided with means for supplying a liquid to the surface of the upper guide roll.   The nip roll and the upper guide roll are transported by the virtual perpendicular, the nip roll, and the upper guide roll with the direction of the virtual perpendicular to the virtual line connecting the center points of the first roll and the second roll of the nip roll being 0 °. The manufacturing apparatus according to claim 7 or 8, wherein an angle formed by a virtual transport line representing a direction of the processed film is arranged to be less than 0 to less than 90 °.   The nip roll which carries out the said resin film in the said processing tank with respect to the nip roll which carries out the said processing film is arrange | positioned in the said processing tank, The any one of Claims 7-9 characterized by the above-mentioned. Manufacturing equipment.

Images