JP2009258193A - Method and apparatus for manufacturing polarizing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polarizing film which has excellent optical characteristics and is broad by suppressing neck-in occurring in uniaxial stretching. <P>SOLUTION: In a stretching apparatus (5), a part of a roll surface of a first stretching roll (21) installed at an upstream side is exposed to atmospheric air and a remaining part is dipped in a solution. A film 11 is held between the first stretching roll (21) and a roll surface (41) of a first nip roll (31) exposed to atmospheric air and then is guided into a solution (15a) while being brought into close contact with the first stretching roll (21). The film 11 is drawn by being held between a second stretching roll (22) and a second nip roll (32) to perform uniaxial stretching by giving it tension. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a polarizing film, which is obtained by uniaxially stretching a polyvinyl alcohol-based film dyed with a dichroic dye such as iodine or a dichroic dye composed of an organic dye in a predetermined solution. The present invention relates to a method and a manufacturing apparatus.

  In recent years, demand for liquid crystal panels, so-called LCDs, has expanded as display devices such as television devices and personal computer monitor devices. The LCD includes a liquid crystal layer made of a liquid crystal composition, two transparent substrates sandwiching and shielding the liquid crystal layer, and two polarizing films attached to the surfaces of the two transparent plates. As a basic structure, a plurality of plates, sheets, and the like to which a predetermined function is added, such as a light guide plate that guides a backlight, are bonded together. The polarizing film has a so-called polarization axis, transmits only light in a predetermined vibration direction, and absorbs light in other vibration directions. The two polarizing filters that make up the LCD are bonded so that their polarization axes are perpendicular to each other, so the backlight illuminated from the back of the LCD is usually shielded and does not reach the surface of the LCD. When a voltage is applied to the liquid crystal, the vibration direction of the light changes in the liquid crystal layer, and the light can pass through the polarizing filter. Thus, in the LCD, an image is displayed by controlling the voltage applied to the liquid crystal.

  As is well known in the art, polarizing films indispensable for LCD production include polyvinyl alcohol films such as polyvinyl alcohol, polyvinyl formal, and polyvinyl acetal, that is, PVA films, dichroic substances such as iodine, and organic dyes. It is manufactured by so-called uniaxial stretching in which a dichroic dye consisting of the above is dyed and stretched in one direction. And in order to obtain predetermined intensity | strength and to protect from humidity, the protective layer which consists of triacetylcellulose (TAC) etc. is bonded together to the polarizing film. Since optical characteristics such as transmittance and degree of polarization affect the brightness and color reproducibility of the LCD, a polarizing film used in the LCD is required to have high transmittance and high degree of polarization.

  When a raw film is uniaxially stretched, shrinkage called neck-in occurs in a direction perpendicular to the stretching direction, that is, in the width direction of the film. The raw material PVA-based film is supplied as a raw material wound up in a roll shape, and the width of the raw material film that is generally distributed is the same standard length. Therefore, unless a particularly wide film is used as a raw material, the width of the polarizing film that can obtain the neck-in size generated by uniaxial stretching is determined. In recent years, LCDs have been increased in size, and a wider polarizing film has been demanded. A technique for obtaining a wide polarizing film by suppressing neck-in while maintaining necessary optical characteristics is demanded. .

  The film is uniaxially stretched between two stretching rolls for feeding out the film, but the peripheral speed of the downstream stretching roll is made larger than the peripheral speed of the upstream stretching roll to give tension to the film. And stretch. At this time, each stretching roll is provided with a nip roll so that the film does not slide on the stretching roll, and the film is sandwiched between the nip roll and the stretching roll and sent out. Typical uniaxial stretching methods include a so-called dry stretching method in which a film is heated in the air using a heating roll as a stretching roll, and a so-called wet stretching method in which the film is stretched while being immersed in a predetermined solution. Is known. The dry stretching method has a drawback that the film is easily broken, and the film cannot be sufficiently stretched, so that it is difficult to obtain necessary optical characteristics. On the other hand, the wet stretching method is easy to obtain necessary optical characteristics because the film is hardly broken and can be sufficiently stretched. Accordingly, in recent years, the wet stretching method has become mainstream.

JP 2008-15000 A

  Patent Document 1 describes a film manufacturing apparatus that performs a wet stretching method, in which a plurality of stretching rolls capable of changing the roll position are provided, and the film can be stretched over a plurality of stages. Has been. By the way, neck-in mainly occurs when the film is stretched, and the longer the distance that the film is stretched, the so-called stretch distance, the harder the constraint in the width direction of the film and the larger the neck-in. In general, since the film is constrained by the roll in a section wound around the roll and is not stretched, the distance between the stretches is given by the length of the film from one stretch roll to the other stretch roll. . In the film manufacturing apparatus described in Patent Document 1, since the roll position can be changed, the distance between the stretches can be shortened and neck-in can be suppressed.

  Even with the film manufacturing apparatus described in Patent Document 1, it is possible to obtain a wide polarizing film by suppressing neck-in while ensuring optical characteristics, but there are also points to be improved. That is, according to the film manufacturing apparatus described in Patent Document 1, the apparent distance between stretching can be shortened, but in practice, as explained in the following, in the same manner as the conventionally known wet stretching method, The distance between stretching is not short.

  FIG. 5 shows a film manufacturing apparatus composed of a stretching tank and a stretching roll for carrying out a conventionally known wet stretching method. The drawing tank 81 is filled with a predetermined solution 82, and is provided in the solution 82 corresponding to the first and second drawing rolls 83 and 84 and the first and second drawing rolls 83 and 84. 1 and 2 nip rolls 85 and 86 are immersed. The first and second guide rolls 87 and 88 are provided at predetermined positions above the stretching tank 81. In such a film manufacturing apparatus, a PVA film 90 on which a dichroic substance made of iodine is dyed is guided by a first guide roll 87, and by the first nip roll 85 and the first stretching roll 83, It is wound so as to exhibit an inverted S shape in the drawing. Further, the PVA film 90 is wound around the first and second stretching rolls 83 and 84 as indicated by reference numeral 91, and is S-shaped in the drawing by the second stretching roll 84 and the second nip roll 86. Is then guided by the second guide roll 88 and fed to the right as indicated by reference numeral 92. In this manufacturing apparatus, the peripheral speed of the second drawing roll 84 on the downstream side is increased with respect to the peripheral speed of the first drawing roll 83 on the upstream side, and tension is applied to the PVA film 90 to perform uniaxial stretching. ing. As already explained, the distance between the stretches is given by the length of the film from the one stretch roll until it contacts the other stretch roll, so it should be the distance shown at 94. However, the solution 82 is entrained from the portion indicated by the arrows 95 and 96, and is thin between the PVA film 90 and the first stretching roll 83, and between the PVA film 90 and the second stretching roll 84. A layer of solution 82 is formed. Then, since the PVA film 90 does not adhere to the first and second stretching rolls 83 and 84, the frictional force does not work sufficiently, and the PVA film 90 in the dotted lines indicated by reference numerals 97 and 98 is also stretched without being constrained. Will be. That is, in this film manufacturing apparatus, the substantial distance between stretching is the distance obtained by adding the lengths of dotted lines indicated by reference numerals 97 and 98 to the apparent distance between stretching 94.

  Also in the film manufacturing apparatus described in Patent Document 1, a thin solution layer is formed between the film and the stretching roll, as in the known film manufacturing apparatus, so that the film is also wound around the stretching roll. It will be stretched. That is, the substantial distance between stretching becomes long, and neck-in cannot be sufficiently suppressed.

  Furthermore, neck-in occurs when the film is dried. A uniaxially stretched film needs to be dried because it contains a certain amount of moisture, but it shrinks in the width direction when the film dries due to the stress that occurs during stretching and remains inside. End up. That is, neck-in occurs. In the film manufacturing apparatus described in Patent Document 1, no particular consideration is given to suppressing neck-in that occurs when the film is dried.

  The present invention aims to provide a method for producing a polarizing film and a production apparatus for carrying out such a production method, which have solved the above-mentioned conventional problems or problems, and specifically, an excellent optical system. Despite the application of a wet stretching method that can produce a polarizing film having characteristics, the distance between the stretching can be substantially shortened, thereby sufficiently suppressing neck-in and obtaining a wide polarizing film. An object of the present invention is to provide a polarizing film manufacturing method and a manufacturing apparatus. Another object of the present invention is to provide a polarizing film manufacturing method and a manufacturing apparatus provided with a film drying method capable of sufficiently suppressing neck-in that occurs when the film is dried.

  In order to achieve the above-mentioned object, the present invention feeds a raw material film sandwiched between a pair of upstream rolls, further pulls it sandwiched between a pair of downstream rolls, and draws tension by the difference in peripheral speed between the upstream and downstream rolls. When the raw film is wet-stretched, one roll constituting the upstream pair of rolls is immersed in the solution so that a part of the roll surface is exposed to the atmosphere. When the raw film is sandwiched between a pair of upstream rolls, it is sandwiched between portions exposed to the atmosphere, and the film is guided into the solution while being in close contact with the roll. Moreover, it is comprised so that it may dry, winding the stretched film around the roll for drying.

  That is, the invention according to claim 1 is a method in which a polyvinyl alcohol film made of polyvinyl alcohol, polyvinyl formal or polyvinyl acetal is dyed with a dichroic substance or a dichroic dye and immersed in a predetermined solution. A method for producing a polarizing film, which is obtained by uniaxially stretching to obtain a polarizing film, wherein the film is sandwiched between a pair of rolls and sent out, and is disposed downstream of the pair of rolls, and the peripheral speed of the pair of rolls The film is configured to be sandwiched between the pair of rolls in the atmosphere and guided into the predetermined solution when the film is pulled and uniaxially stretched by another pair of rolls driven at a higher peripheral speed. . Moreover, invention of Claim 2 is comprised so that the said uniaxial stretching may be repeated in multiple times in the method of Claim 1. Furthermore, the invention according to claim 3 is configured to wind the uniaxially stretched film around a roll for drying in the method according to any one of claims 1 and 2.

  The invention according to claim 4 is uniaxially stretched while a polyvinyl alcohol film made of polyvinyl alcohol, polyvinyl formal or polyvinyl acetal is dyed with a dichroic substance or a dichroic dye and immersed in a predetermined solution. A polarizing film manufacturing apparatus for obtaining a polarizing film, wherein the manufacturing apparatus includes a stretching tank filled with a predetermined solution, a first pair of rolls fed with the film interposed therebetween, and the first pair. A first pair of rolls, the second pair of rolls being arranged on the downstream side of the first roll and comprising a second pair of rolls driven at a faster peripheral speed than the first pair of rolls with the film interposed therebetween. One of the rolls is provided in the stretching tank so that part of the roll surface is exposed to the atmosphere and the other part is immersed in the solution of the solution, and the first pair of rolls The other roll is constructed as a position in contact with one roll face of said first pair of rolls is provided in the drawing bath to be positioned into the atmosphere. The invention according to claim 5 is the manufacturing apparatus according to claim 4, wherein a pair of rolls that are fed across the film are provided in a plurality of stages from the upstream side to the downstream side, and the pair of rolls are The downstream side is driven at a higher peripheral speed, and one of these rolls is partly exposed to the atmosphere and the other part is in the solution of the solution. The other roll of the pair of rolls is provided in the stretching tank so that the position in contact with the one roll surface is located in the atmosphere. The invention according to claim 6 is the manufacturing apparatus according to any one of claims 4 and 5, wherein a drying device for drying the uniaxially stretched film is provided downstream of the stretching device, The drying equipment Is configured with the roll for drying adapted to be temperature adjusted film is wound, and a air nozzle for blowing drying air to the roll surface of the roll for the drying.

  As described above, according to the present invention, since the film is sandwiched between a pair of rolls in the atmosphere and the film is guided into the solution, the solution is not caught between the roll surface and the film. Accordingly, since the film is substantially closely adhered to the roll surface and restrained, the film is not stretched on the roll surface, and the substantial distance between the stretches can be shortened. For this reason, a wide polarizing film can be obtained by suppressing neck-in. Further, since the film is introduced into the solution and wet-stretched, there is little risk of the film breaking even if it is sufficiently stretched, and a polarizing film having necessary optical characteristics can be easily produced. According to the invention described in claim 2, since the wet stretching method as described above is performed a plurality of times, that is, a plurality of stages, the film can be sufficiently stretched while suppressing the neck-in, and more excellent in optical properties. A wide polarizing film can be obtained. Furthermore, according to the invention described in claim 3, since the uniaxially stretched film is wound around a drying roll and dried, even if the stress generated during stretching remains in the film, the film becomes a drying roll. It closely adheres and dries and shrinks in the width direction. Therefore, a wide polarizing film can be obtained. In addition, according to the invention described in claim 4, since the stretching apparatus has only a stretching tank filled with a predetermined solution and a first and second pair of rolls, a conventionally known stretching apparatus capable of performing a wet stretching method. There is no difference in the necessary configuration equipment and components. Therefore, in a conventionally known stretching apparatus, the stretching apparatus according to the present invention can be configured only by changing the arrangement of the rolls of the component parts, and a polarizing film manufacturing apparatus can be configured at low cost.

  Embodiments of the present invention will be described below. As schematically shown in FIG. 1A, the polarizing film manufacturing apparatus 1 according to the present embodiment includes a swelling tank 2 that swells a raw material film, a dichroic material such as iodine, or an organic material. A dyeing tank 3 for dyeing a film with a dichroic dye comprising a dye, a crosslinking tank 4 for adding a crosslinking agent to give a polymer a network structure and giving the film a predetermined strength, and stretching the film in a predetermined solution Stretching device 5, complementary color tank 6 for adjusting the hue of the stretched film, first drying device 7 for drying the film containing moisture to a predetermined moisture content, and second drying device 8 for drying the film. , And a plurality of nip rolls N, N,..., And a guide roll 2b, 3b, A,.

In such a polarizing film manufacturing apparatus 1, the swelling tank 2, the dyeing tank 3, the crosslinking tank 4, the complementary color tank 6, and the second drying apparatus 8 are the tanks and apparatuses of the conventionally known polarizing film manufacturing apparatus. The configuration is the same, which will be briefly described below.
The swelling tank 2 is filled with a predetermined solution 2a, and when the raw film is guided by a guide roll 2b provided in the solution 2a and immersed in the solution 2a, dirt adhered to the surface of the film In addition, the anti-blocking agent and the like added to the film are washed, and the film absorbs appropriate moisture and swells. By this swelling, it is possible to prevent the occurrence of uneven dyeing at the time of dyeing in the subsequent process. Such a solution 2a is prepared by adding potassium iodide as needed to so-called production water adjusted so that components such as minerals do not exceed a predetermined concentration and a pH value is within a predetermined range. Boric acid, softener, etc. are added at a predetermined concentration.

  The dyeing tank 3 is filled with a solution 3a in which a dichroic dye composed of a dichroic substance such as iodine or an organic dye is added to a predetermined production water at a predetermined concentration. Therefore, when the film is immersed in the solution by the guide roll 3b provided in the solution 3a, the film is dyed with a dichroic substance or a dichroic dye. The crosslinking tank 4 is filled with a solution 4a in which a predetermined production water is added with a boron compound such as boric acid and borax, and a crosslinking agent such as glyoxal and glutaraldehyde. When the film is immersed in the solution 4a by the guide roll 4b provided in the solution 4a, the polymer constituting the film is cross-linked to give a predetermined strength to the film.

  The complementary color tank 6 is filled with a solution 6a obtained by adding a small amount of iodine compound such as potassium iodide or sodium iodide to predetermined production water. When guided by the guide roll 6b provided in the tank 6 and the film is immersed in the solution 6a, unnecessary residues such as boric acid adhered to the film in other pretreatments are washed, and the hue is also Adjusted. As is well known in the art, the second drying device 8 is also provided with a blower for blowing hot air, an electric panel heater, and the like inside, and the film dries while the film is fed through the device.

  The stretching apparatus 5 according to the first embodiment will be described. Although the stretching apparatus 5 is partly different, most of the stretching apparatus 5 is configured in the same manner as a conventionally known stretching apparatus. As shown in FIG. Each of the stretching tank 15 placed so as to have a depth, the first to fourth stretching rolls 21, 22,... For stretching the film, and the first to fourth stretching rolls 21, 22,. The first to fourth nip rolls 31, 32,... Sandwiching the film and the guide rolls 36, 37 are provided. The solution 15a may be added with a boron compound, iodide, or the like, but in the present embodiment, the solution 15a is purified water that has been purified so that the concentrations of minerals, ions, and the like are below a reference value. The stretching apparatus 5 according to the present embodiment is characterized by the positions of the first to fourth stretching rolls 21, 22,... And is not completely submerged in the solution 15a. That is, the 1st-4th extending | stretching roll 21,22, ... is sunk in the solution 15a in the state which the predetermined roll surface was exposed in air | atmosphere as the figure shows. Among the first to fourth stretching rolls 21, 22,..., The distance between the first and second stretching rolls 21, 22 and the distance between the third and fourth stretching rolls 23, 24 are relatively narrow. The interval between the two or three stretching rolls 22 and 23 is relatively wide. The first to fourth nip rolls 31, 32,... Are provided so as to be in contact with the roll surfaces of the first to fourth stretching rolls 21, 22,. The films can be sandwiched in the atmosphere by 21, 22,... And the first to fourth nip rolls 31, 32,. The second and fourth nip rolls 32 and 34 will be described in more detail. The axial centers of the second and fourth nip rolls 32 and 34 are higher than those vertically above the axial centers of the second and fourth stretching rolls 22 and 24. The three stretching rolls 21 and 23 are arranged at positions close to each other. Therefore, when the film is stretched between the first and second stretching rolls 21 and 22 and between the third and fourth stretching rolls 23 and 24, the distance between stretching is sufficiently short. A guide roll 36 is provided in the vicinity of the intermediate position between the second and third stretching rolls 22 and 23 and submerged in the solution 15a, and a guide roll 37 is provided downstream of the fourth stretching roll 24. The film is guided and sent smoothly downstream.

  The drying apparatus according to the present embodiment, that is, the first drying apparatus 7 will be described. As shown in FIG. 1C, the first drying device 7 includes a pair of draining rolls 51 and 51 that drains the film while taking the film, and air that blows off water droplets adhering to the film. Knives 52, 52, a drying roll 53 that dries while winding the film, a predetermined roll surface of the drying roll 53, an air nozzle 54 that blows dry air on the film, and a drying roll 53 A nip roll 55 provided so as to be in contact with the roll surface and a guide roll 57 are included. The drying roll 53 has a mirror-finished roll surface and is provided with heating means such as a heater inside so that the roll surface can be maintained at a predetermined temperature, for example, 50 ° C. ± 5 ° C. Yes.

  The effect | action of the polarizing film manufacturing apparatus 1 which concerns on this Embodiment is demonstrated. A polyvinyl alcohol film such as polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, or the like, a so-called PVA film is applied to the film that is a raw material of the polarizing film. The raw material PVA-based film is supplied as a raw material that is aligned in a predetermined width and wound into a roll. Such an original fabric 10 is attached to the most upstream part of the polarizing film manufacturing apparatus 1, that is, in the vicinity of the swelling tank 2. The film 11 is pulled out from the original fabric 10 and guided to the swelling tank 2 to swell in the solution 2a of the swelling tank 2. The swollen film 11 is guided to the dyeing tank 3 and dyed in the solution 3a. Next, the film 11 is cross-linked in the solution 4 a of the cross-linking tank 4, and then guided to the stretching device 5 via the nip roll N.

  The film 11 is wound around each roll 21, 22, ..., 31, 32, ... in the stretching apparatus 5 as follows. First, while winding the film 11 around the first nip roll 31 about half a turn, the film 11 is sandwiched between the first drawing roll 21 and the first nip roll 31 at a position indicated by reference numeral 41 in the atmosphere, and then the first drawing roll 21 To the solution 15a while being in close contact therewith. Accordingly, the film 11 is wound around the first nip roll 31 and the first stretching roll 21 so as to exhibit an inverted S shape as shown in FIG. 1A when viewed from the axial direction of the roll. Will be. Next, the film 11 is pulled out and pulled out to the atmosphere while being wound around the second stretching roll 22, and sandwiched between the second stretching roll 22 and the second nip roll 32 in the atmosphere, and then again to the second stretching roll 22. It guide | induces in the solution 15a, winding. The film 11 is drawn out into the atmosphere after passing through the guide roll 36 submerged in the solution 15a. The film 11 is wound around the third nip roll 33 and the third stretching roll 23 so as to exhibit an inverted S shape, and is again guided into the solution 15a. At this time, the film 11 is sandwiched between the third drawing roll 23 and the third nip roll 33 at a position indicated by reference numeral 43 in the atmosphere. The film 11 is pulled out and pulled out to the atmosphere while being wound around the fourth stretching roll 24, and after being sandwiched between the fourth stretching roll 24 and the fourth nip roll 34 in the atmosphere, the film 11 is downstream via the guide roll 37. To send.

  The first to fourth stretching rolls 21, 22,... Can be independently driven by controlling the peripheral speed, and the second stretching roll 22 is the third stretching roll rather than the first stretching roll 21. The circumferential speed of the fourth stretching roll 24 is greater than that of 23. Therefore, the film 11 is uniaxially stretched between the first and second stretching rolls 21 and 22 and further uniaxially stretched between the third and fourth stretching rolls 23 and 24. Although the film 11 is not actively stretched between the second and third stretching rolls 22 and 23, the third stretching roll 23 is slightly smaller than the second stretching roll 2 so that the film 11 does not loosen. Since the peripheral speed is increased to give a predetermined tension, the film 11 is slightly stretched. The state in which the film 11 is uniaxially stretched between the first and second stretching rolls 21 and 22 will be described in detail. As shown in FIG. 2, the film 11 is sandwiched between the first stretching roll 21 and the first nip roll 31 at a portion indicated by the reference numeral 41 in the atmosphere, and is attached to the first stretching roll 21. It is guided into the solution 15a while being in close contact. Therefore, the solution 15a is not caught between the film 11 and the first stretching roll 21 from the direction indicated by the arrow Y1. Since the layer of the solution 15a is not formed between the film 11 and the roll surface of the first stretching roll 21, no slip occurs. Therefore, when the film 11 is uniaxially stretched in the solution 15a, the section of the film 11 to be stretched, that is, the distance between the stretches is only the dotted line portion indicated by the reference numeral 46. Similarly, when the film 11 is uniaxially stretched between the third and fourth stretching rolls 23 and 24, the distance between the stretching is also short. That is, since the film 11 is sandwiched between the third stretching roll 23 and the third nip roll 33 at a portion indicated by reference numeral 43 in the atmosphere, the solution 15a does not enter from the direction of the arrow Y2. Accordingly, since the film 11 does not slide in close contact with the third stretching roll 23, the film 11 is stretched only at the dotted line portion indicated by reference numeral 47. According to the stretching apparatus 5 according to the present embodiment, the distance between the stretching can be shortened, so that the neck-in can be sufficiently suppressed.

  The film 11 uniaxially stretched by the stretching device 5 is guided to the complementary color tank 6 via the guide roll A and the nip roll N. The film 11 is immersed in the solution 6a of the complementary color tank 6 to adjust the hue. The film 11 is guided to the first drying device 7 via the nip roll N.

  When the film 11 is drawn off by the draining rolls 51, 51, the film 11 is drained to remove most of the water droplets. Water droplets that remain slightly adhered are blown off by the air knives 52 and 52. After removing water droplets adhering to the surface of the film 11 in this way, the film 11 is wound around the drying roll 53. The film 11 is heated by controlling the roll surface of the drying roll 53 to a predetermined temperature, and drying air is blown onto the film 11 from the air nozzle 54. The film 11 is dried while being in close contact with the roll surface of the drying roll 53 by the drying air and the heat of the drying roll 53. Since shrinkage in the width direction of the film 11 is regulated by the roll surface, neck-in that occurs during drying is suppressed. The film 11 is sent to the second drying device 8 via the nip roll 55 and the guide roll 57. Although the film 11 may be completely dried by the first drying device 7, in the present embodiment, the film 11 is removed so that the moisture content is about 30% in the first drying device 7. It is dry. This is because when the moisture content is 30% or less, the neck-in generated after the film is dried by a conventionally known method is relatively small.

  When the film 11 is dried by the second drying device 8 as is conventionally known, a polarizing film is obtained. The obtained polarizing film is wound up by a winder not shown in the figure. Or it sends to another apparatus, and in order to obtain predetermined intensity | strength and to protect from humidity, the protective layer which consists of triacetylcellulose (TAC) etc. is bonded together.

  FIG. 3 shows a stretching apparatus 5 ′ according to the second embodiment. Elements similar to those of the stretching apparatus 5 according to the first embodiment are given the same reference numerals and will not be described in detail. In the stretching apparatus 5 ′ according to the second embodiment, the positions of the second stretching roll and the second nip roll are different from those of the stretching apparatus 5 according to the first embodiment. That is, the second stretching roll 22a and the second nip roll 32a are both provided in the atmosphere. Although it will be easily understood by those skilled in the art and will not be described, even in this case, the substantial distance between stretching is short. As indicated by the dotted line rolls in the figure, both the second stretching roll 22b and the second nip roll 32b may be immersed in the solution 15a. Even in this case, the substantial distance between stretching is similarly short. Similarly to the stretching apparatus 5 according to the first embodiment, the stretching apparatus 5 ′ according to the second embodiment can sufficiently suppress the neck-in and obtain a wide polarizing film.

  FIG. 4 shows a stretching apparatus 5 ″ according to the third embodiment. Elements similar to the constituent elements of the stretching device 5 according to the first embodiment are not described in detail by adding a dash “′” to the same reference number. The stretching apparatus 5 '' according to the third embodiment is an apparatus in which the stretching apparatus 5 according to the first embodiment is modified. That is, in the stretching apparatus 5 according to the first embodiment, the fifth stretching roll 25 is provided downstream of the second stretching roll 22 'so as to be adjacent to the second stretching roll 22'. Therefore, in the stretching apparatus 5 ″ according to the third embodiment, uniaxial stretching can be performed between the second and fifth stretching rolls 22 ′ and 25.

  Using the polarizing film manufacturing apparatus 1 which concerns on this Embodiment, it uniaxially stretched and obtained polarizing film S1. For comparison, the first to fourth stretching rolls were uniaxially stretched while completely immersed in the solution, and dried without using a drying roll to obtain a polarizing film S2. That is, the polarizing film S2 was obtained by uniaxially stretching by a conventionally known wet stretching and drying by a conventionally known drying method. The manufacturing conditions and comparison results are summarized in the following table.

  From Example 1 above, it was found that a wide polarizing film S1 was obtained despite having optical properties almost equivalent to those of the polarizing film S2 obtained by a conventionally known wet stretching method and drying method. As for the width of the polarizing film, only a polarizing film having a width of about 50% of the width of the original fabric can be obtained by a conventionally known wet stretching method and drying method, whereas the polarizing film according to the present embodiment. It was found that with this manufacturing method, a polarizing film having a width of about 70% of the width of the original fabric can be obtained.

  The polarizing film manufacturing apparatus of this invention is not limited to the said embodiment, It can implement in various forms. For example, in the stretching apparatus 5 according to the first embodiment, the guide roll 36 provided between the second and third stretching rolls 22 and 23 is described as being completely submerged in the solution. However, the guide roll 36 may be provided in the atmosphere, or only a part of the roll surface may be submerged in the solution. Further, the stretching roll is not specifically described as adjusting the temperature, but it is also possible to provide a heating body inside the stretching roll to heat the film and heat the entire stretching roll. When carried out in this way, the film is more easily stretched. The roll diameter can also be modified. In the figure, the nip roll paired with the drawing roll is depicted as having a different roll diameter, but it can also be configured with the same diameter. Further, the roll immersed in the solution while exposing a part of the roll surface to the atmosphere in the stretching tank may be a nip roll instead of the stretching roll. Furthermore, you may provide two or more rolls for drying in a drying apparatus. If two drying rolls are provided and the surface of the film wound around each of the drying rolls is changed, the film can be dried from both sides, so that it can be uniformly dried.

  According to the polarizing film manufacturing apparatus of the present invention, it is possible to obtain a wide film while suppressing neck-in, and therefore, it can be applied to manufacturing a film for other uses other than the polarizing film.

It is a figure which shows typically the polarizing film manufacturing apparatus which concerns on this Embodiment, The (a) is a side view which shows typically the whole polarizing film manufacturing apparatus, The (a) is extending | stretching which concerns on this Embodiment The side view which shows an apparatus typically, The (c) is a side view which shows typically the drying apparatus which concerns on this Embodiment. It is a side view for demonstrating the effect | action of the extending | stretching apparatus which concerns on this Embodiment. It is a side view which shows typically the extending | stretching apparatus which concerns on 2nd Embodiment. It is a side view which shows typically the extending | stretching apparatus which concerns on 3rd Embodiment. It is a side view which shows typically the extending | stretching apparatus which implements a conventionally well-known wet extending | stretching method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polarizing film manufacturing apparatus 2 Swelling tank 3 Dyeing tank 4 Crosslinking tank 5 Stretching apparatus 6 Complementary color tank 7 First drying apparatus 8 Second drying apparatus 10 Original fabric 11 Film 15 Stretching tank 15a Solution 21, 22, 23, 24 1st to 4th stretching rolls 31, 32, 33, 34 1st to 4th nip rolls 52, 52 Air knife 53 Drying roll 54 Air nozzle

Claims (6)

A polarizing film obtained by dyeing a polyvinyl alcohol film made of polyvinyl alcohol, polyvinyl formal or polyvinyl acetal with a dichroic substance or a dichroic dye and uniaxially stretching the film while immersing it in a predetermined solution. A manufacturing method of
The film is sandwiched between a pair of rolls and sent out, and is disposed on the downstream side of the pair of rolls and is sandwiched between another pair of rolls driven at a peripheral speed greater than the peripheral speed of the pair of rolls. When uniaxially stretching
The method for producing a polarizing film, wherein the film is sandwiched between the pair of rolls in the air and guided into the predetermined solution. The method according to claim 1, wherein the uniaxial stretching is repeated a plurality of times. The method according to claim 1, wherein the uniaxially stretched film is wound around a drying roll and dried. A polarizing film obtained by dyeing a polyvinyl alcohol film made of polyvinyl alcohol, polyvinyl formal or polyvinyl acetal with a dichroic substance or a dichroic dye and uniaxially stretching the film while immersing it in a predetermined solution. Manufacturing equipment,
The manufacturing apparatus is disposed on a downstream side of the stretching tank filled with a predetermined solution, a first pair of rolls that are fed with a film interposed therebetween, and the first pair of rolls, and the first pair of rolls sandwiched with the film. A stretching device comprising a second pair of rolls driven at a faster peripheral speed than the pair of rolls of one;
One roll of the first pair of rolls is provided in the stretching tank so that a part of the roll surface is exposed to the atmosphere and the other part is immersed in the solution of the solution,
The other roll of the first pair of rolls is provided in the stretching tank so that a position in contact with one roll surface of the first pair of rolls is located in the atmosphere. Polarizing film manufacturing equipment. 5. The manufacturing apparatus according to claim 4, wherein a pair of rolls fed with a film interposed therebetween are provided in a plurality of stages from the upstream side to the downstream side, and the pair of rolls are driven at a faster peripheral speed toward the downstream side. As well as
One roll of these pair of rolls is provided in the stretching tank with a part of the roll surface exposed to the atmosphere and the other part immersed in the solution of the solution, and the pair of rolls The other roll of the roll is provided in the stretching tank so that a position in contact with the pair of one roll surfaces is located in the atmosphere. In the manufacturing apparatus according to any one of claims 4 and 5, a drying device for drying a uniaxially stretched film is provided downstream of the stretching device,
The drying apparatus includes a drying roll whose temperature is adjusted and a film is wound thereon, and an air nozzle that blows drying air onto a roll surface of the drying roll. , Polarizing film manufacturing equipment.

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