KR102604343B1 - Manufacturing method of polarizing film, manufacturing device and control system of polarizing film - Google Patents

Abstract

(Problem) A method for producing a polarizing film capable of stabilizing the conveyance of a polarizer between a processing tank and a bonding roll even when the moisture content of the polarizer on the oven exit side is low, etc. are provided. (Solution) The method for manufacturing the polarizing film (F) according to the present invention is to arrange the first tension cut roll (20) for conveying the polarizer (F1) between the processing tank (2) and the bonding roll (7). In addition, a tensiometer 30 is disposed between the treatment tank and the bonding roll and on the downstream side of the first tension cut roll, and the control device 40 controls the first tension cut so that the tension measured by the tensiometer is a predetermined value. Controls the peripheral speed of the roll. In addition, after executing the above control, the peripheral speed of the first tension cut roll 20c disposed on the exit side of the treatment tank is measured, and the measured peripheral speed P1c' of the first tension cut roll and the second tension cut roll 60 ) The peripheral speed of the second tension cut roll is controlled so that the ratio of the peripheral speed is a predetermined value.

Description

Manufacturing method of polarizing film, manufacturing device and control system of polarizing film

In the present invention, a raw film is dyed with a dichroic material in a treatment tank and stretched uniaxially, then dried in an oven to produce a polarizer, and a polarizer and a protective film are bonded together with a bonding roll to produce a polarizing film. It relates to a method, a device and a control system for manufacturing a polarizing film. In particular, the present invention relates to a polarizing film manufacturing method, a polarizing film manufacturing apparatus, and a control system capable of stabilizing the transport of the polarizer between the processing tank and the bonding roll even if the moisture content of the polarizer on the oven exit side is low.

Conventionally, a polarizing film containing a polarizer has been used as a structural material for liquid crystal displays, polarized sunglasses, etc. A polarizing film is composed of, for example, a polarizer dyed with a dichroic substance such as iodine, and a protective film that is adhered to the polarizer and protects the polarizer.

For example, as described in Patent Document 1, the polarizing film is a series of processes from manufacturing a long strip-shaped polarizer to bonding a long strip-shaped protective film to obtaining a long strip-shaped polarizing film. It is manufactured using a roll-to-roll method performed on one production line.

Japanese Patent Publication No. 2004-341515

FIG. 3 is a diagram schematically showing a schematic configuration example of a manufacturing apparatus and a control system used in a conventional roll-to-roll method of manufacturing a polarizing film. The arrow indicated by the solid line shown in FIG. 3 means the conveyance direction of each film.

As shown in FIG. 3, in the conventional method for producing a polarizing film, first, the raw film F0 wound on the feeding roll 1 is fed, and then fed into the processing tank 2 (for example, the raw film ( F0) is immersed in a treatment bath (consisting of a swelling treatment tank, a dyeing treatment tank, a crosslinking treatment tank, a stretching treatment tank, and a washing treatment tank) in order from the upstream side of the conveyance direction, and dichroic substances such as iodine and dichroic dyes are added. It is dyed and uniaxially stretched. Next, the polarizer (F1) is obtained by drying in the oven (3). Next, for example, an active energy ray-curable adhesive is applied to both surfaces of the polarizer F1 using the coating machine 6. Additionally, for example, an active energy ray-curable adhesive is applied to one side of the protective film (F2) fed from a feeding roll (not shown) using a coating machine (not shown). Then, the adhesive-coated protective film (F2) is bonded to both sides of the adhesive-coated polarizer (F1) using the bonding roll 7. After that, although not shown altogether, the adhesive between the polarizer (F1) and the protective film (F2) is cured by irradiating active energy rays from an active energy ray irradiation device, and then dried in an oven, and, if necessary, other films ( A polarizing film is manufactured by laminating a surface protection film, etc.).

As shown in FIG. 3, the conventional manufacturing apparatus is disposed between the treatment tank 2 and the bonding roll 7, and polarizer F1 (processed in the treatment tank 2 and then dried in the oven 3) It is provided with a first tension cut roll (20) for conveying the raw film (F0) before processing) and a second tension cut roll (60) for conveying the raw film (F0) in the processing tank (2). there is. In the example shown in FIG. 3, three first tension cut rolls 20a to 20c are arranged as the first tension cut roll 20, and five second tension cut rolls are arranged as the second tension cut roll 60. (60a to 60e) are arranged. In the example shown in FIG. 3, the first tension cut roll 20 and the second tension cut roll 60 are both nip rolls.

The conventional control system 100A includes a control device 40 and an encoder 50.

The encoder 50 measures the rotation speed of the bonding roll 7 and outputs it to the control device 40. The control device 40 calculates the peripheral speed (P0') of the bonding roll 7 based on the input rotation speed of the bonding roll 7 and the pre-stored outer diameter of the bonding roll 7. do. Then, the control device 40 adjusts the peripheral speed of the first tension cut roll 20 so that the ratio of the peripheral speed P0' of the bonding roll 7 and the peripheral speed of the first tension cut roll 20 is a predetermined value. Control (ratio constant control). Specifically, assuming that the peripheral speed of the first tension cut roll 20a is P1a, the peripheral speed of the first tension cut roll 20b is P1b, and the peripheral speed of the first tension cut roll 20c is P1c, the control device 40 Determine the peripheral speeds (P1a, P1b, and P1c) so that P1a/P0' = α1, P1b/P0' = α2, P1c/P0' = α3 (α1, α2, and α3 are predetermined integers), and determine each peripheral speed ( A control signal is transmitted to the driving unit (motor, etc., not shown) of the first tension cut rolls 20a to 20c so that the first tension cut rolls 20a to 20c rotate respectively at P1a to P1c. In general, since the bonding roll 7 rotates at a constant predetermined peripheral speed, the first tension cut roll 20 also rotates at a constant peripheral speed.

Moreover, in the example shown in FIG. 3, the peripheral speed P0' of the bonding roll 7 is calculated based on the result of measuring the rotation speed of the bonding roll 7, and based on the calculated peripheral speed P0' , the peripheral speed of the first tension cut roll 20 is controlled, but without actually measuring or calculating the peripheral speed of the bonding roll 7, the first tension cut roll 7 is controlled based on the set value of the circumferential speed or the rotation speed of the bonding roll 7. 1 In some cases, the peripheral speed of the tension cut roll 20 is controlled.

Additionally, the control device 40 adjusts the peripheral speed of the second tension cut roll 60 so that the ratio between the peripheral speed P0' of the bonding roll 7 and the peripheral speed of the second tension cut roll 60 is a predetermined value. Control (ratio constant control). Specifically, the peripheral speed of the second tension cut roll 60a is P2a, the peripheral speed of the second tension cut roll 60b is P2b, the peripheral speed of the second tension cut roll 60c is P2c, and the peripheral speed of the second tension cut roll 60d is P2c. ) If the peripheral speed of the second tension cut roll 60e is P2d and the peripheral speed of the second tension cut roll 60e is P2e, then the control device 40 has P2a/P0' = β1, P2b/P0' = β2, P2c/P0' = β3, P2d. The peripheral speeds (P2a, P2b, P2c, P2d, and P2e) are determined so that /P0' = β4, P2e/P0' = β5 (β1, β2, β3, β4, and β5 are predetermined integers), and each peripheral speed (P2a ~ A control signal is transmitted to the drive unit (motor, etc., not shown) of the second tension cut rolls 60a to 60e so that the second tension cut rolls 60a to 60e rotate respectively at P2e). As described above, generally, since the bonding roll 7 rotates at a constant peripheral speed, the second tension cut roll 60 also rotates at a constant peripheral speed.

Constant control of the circumferential speed of the second tension cut roll 60 is necessary to stretch the raw film F0 at a predetermined stretching ratio.

In the method for manufacturing a polarizing film using the conventional control system 100A described above, the peripheral speed of the first tension cut roll 20 that conveys the polarizer F1 between the processing tank 2 and the bonding roll 7 is set to It is controlled by constant ratio control, and the set tension at each position of the conveyed polarizer F1 is determined by each ratio (α1 to α3). However, the tension actually generated in the polarizer (F1) varies greatly depending on the state of the polarizer (F1). If the tension actually generated in the polarizer (F1) fluctuates greatly, there may be a problem in conveying the polarizer (F1). Additionally, if excessive tension occurs, the polarizer F1 may break. And even if a polarizing film is manufactured under the same manufacturing conditions, the reproducibility of the tension actually generated in the polarizer (F1) is not good. For this reason, it is necessary to fine-tune each ratio (α1 to α3) manually by the operator.

The method of transporting the polarizer (F1) (transferring between the treatment tank 2 and the bonding roll 7) in the conventional method of producing a polarizing film is likely to cause problems when the polarizer (F1) is relatively large and expandable. does not occur In other words, if the polarizer (F1) is able to expand and contract greatly, even if the actual tension fluctuates greatly, the influence of the tension fluctuation is alleviated by the polarizer (F1) stretching and contracting.

However, in recent years, polarizer (F1) with a low moisture content (for example, the moisture content of the polarizer (F1) on the exit side of the oven 3 is 15% or less) has been manufactured.

Since the polarizer (F1) with a low moisture content hardly expands or contracts, in the conventional method of producing a polarizing film, the influence of tension fluctuations is difficult to alleviate, causing problems in transport of the polarizer (F1) or breaking the polarizer (F1). There is a problem that the risk of harm is increasing.

Therefore, the present invention aims to provide a polarizing film manufacturing method, a polarizing film manufacturing apparatus, and a control system capable of stabilizing the transport of the polarizer between the treatment tank and the bonding roll even if the moisture content of the polarizer on the oven exit side is low. Do this.

In order to solve the above problems, the present invention involves dyeing a raw film with a dichroic material in a treatment tank and stretching it uniaxially, drying it in an oven to produce a polarizer, and bonding the polarizer and the protective film together with a bonding roll. A method of manufacturing a polarizing film, comprising: arranging a first tension cut roll for transporting the polarizer between the processing tank and the bonding roll; and disposing a first tension cut roll between the processing tank and the bonding roll and downstream of the first tension cut roll. A method for manufacturing a polarizing film is provided, including a first control step of disposing a tension meter on the side and controlling the peripheral speed of the first tension cut roll so that the tension measured by the tension meter becomes a predetermined value.

The “tension cut roll” in the present invention (the first tension cut roll and the second tension cut roll in the preferred method described later) does not cause the film to slip on the roll, and has tension on the upstream and downstream sides of the roll. It refers to a roll that can control a car, and as a tension cut roll, for example, a nip roll or a suction roll can be used.

In addition, the "downstream side" in this invention means the downstream side in the conveyance direction of a polarizer or a raw film.

According to the present invention, in the first control process, the peripheral speed of the first tension cut roll is controlled so that the tension measured with a tension meter disposed downstream of the first tension cut roll is a predetermined value (hereinafter, this is appropriately referred to as (Referred to as “constant tension control”). In other words, since the circumferential speed of the first tension cut roll is controlled so that the actually measured tension is a predetermined value, even if the moisture content of the polarizer on the oven exit side is low, the variation in tension that actually occurs in the polarizer is reduced, thereby stabilizing the conveyance of the polarizer. It is possible to do so.

Preferably, a plurality of the tension meters and the first tension cut rolls are arranged alternately between the treatment tank and the bonding roll, and in the first control process, the tension meters and the first tension cut rolls are arranged at the most downstream side. 1 After the peripheral speed is controlled by the combination of the tension cut roll, the peripheral speed is controlled by the combination of the tension meter and the first tension cut roll located on the upstream side compared to the combination located on the most downstream side. Executes sequentially toward .

In the above preferred method, “upstream side” means the upstream side of the conveyance direction of the polarizer or raw film. In addition, in the above preferred method, "control of peripheral speed by combination of the tensiometer disposed most downstream and the first tension cut roll" means that the tension measured by the tensiometer disposed most downstream is predetermined. This means controlling the peripheral speed of the first tension cut roll disposed on the most downstream side so that the value is reached. In addition, in the above preferred method, "control of peripheral speed by a combination of the tension meter and the first tension cut roll disposed on the upstream side rather than the combination disposed on the most downstream side" means the tension disposed on the most downstream side. This means controlling the peripheral speed of the first tension cut roll disposed upstream of the tensiometer and immediately adjacent to the tensiometer so that the tension measured by the tensiometer disposed upstream of the system becomes a predetermined value. In addition, in the above preferred method, "executed sequentially toward the upstream side" means that from control of the peripheral speed by a combination of the tension meter and the first tension cut roll arranged on the most upstream side, This means that control of the peripheral speed by a combination of the tension meter and the first tension cut roll is sequentially performed toward the upstream side.

For example, when three first tension cut rolls and three tension meters are arranged (in order from the downstream side, tensiometer (30a), first tension cut roll (20a), tension meter (30b), first In the case where the tension cut roll 20b, the tension meter 30c, and the first tension cut roll 20c are arranged, a first tension cut roll ( After controlling the peripheral speed of 20a), the peripheral speed of the first tension cut roll 20b is controlled so that the tension measured by the tensiometer 30b is a predetermined value, and then the tension measured by the tensiometer 30c is This means controlling the peripheral speed of the first tension cut roll 20c so that it reaches this predetermined value.

According to the above preferred method, when a plurality of tension meters and first tension cut rolls are arranged alternately, the peripheral speed is controlled by a combination of the tension meter and first tension cut roll arranged at the most downstream side, Since the peripheral speed is controlled sequentially toward the combinations arranged upstream, the control does not diverge and stable peripheral speed control is possible. As a result, in the case of arranging a plurality of tension meters and first tension cut rolls alternately, the variation in tension that actually occurs in the polarizer is reduced, making it possible to stabilize the conveyance of the polarizer.

Preferably, after arranging the first tension cut roll on the exit side of the processing tank and arranging a second tension cut roll for transporting the raw film in the processing tank, and executing the first control process, Measure the peripheral speed of the first tension cut roll disposed on the exit side of the treatment tank, and ensure that the ratio of the measured peripheral speed of the first tension cut roll and the peripheral speed of the second tension cut roll is a predetermined value. 2. It includes a second control process for controlling the peripheral speed of the tension cut roll.

In the present invention, since the circumferential speed of the first tension cut roll is controlled by constant tension control, the circumferential speed of the first tension cut roll disposed on the exit side of the treatment tank is constant, unlike the conventional case where it is controlled by constant ratio control. Rather, it fluctuates.

According to the above preferred method, in the second control process, basically, the ratio of the peripheral speed of the first tension cut roll disposed on the exit side of the treatment tank and the peripheral speed of the second tension cut roll is a predetermined value, and the second tension cut roll is adjusted to a predetermined value. The peripheral speed of the tension cut roll is controlled, that is, constant ratio control is performed. However, since the actually measured peripheral speed is used as the circumferential speed of the first tension cut roll disposed on the exit side of the treatment tank, which serves as the basis for the ratio, the circumferential speed of the first tension cut roll disposed on the exit side of the treatment tank fluctuates as described above. Even if this is done, constant ratio control can be appropriately performed, and it is possible to stretch the raw film at a predetermined predetermined stretching ratio.

The present invention is preferably used when the moisture content of the polarizer on the exit side of the oven is 15% or less. That is, because the moisture content is low, it is preferably used for polarizers that hardly expand or contract.

In addition, “moisture content of a polarizer” means the ratio of moisture contained in the polarizer after being dried in an oven. Specifically, the weight of the polarizer after drying in an oven (weight of the polarizer after drying) and the weight of the polarizer after substantially removing moisture from the dried polarizer (weight of the polarizer after complete drying) were respectively measured, and the following It is obtained by substituting each weight into the equation.

Moisture content of polarizer = (weight of polarizer after drying - weight of polarizer after complete drying)/weight of polarizer after drying × 100

The present invention is preferably used when the thickness of the polarizer on the oven exit side is 20 μm or less. That is, because the thickness is thin, it is preferably used for polarizers that are prone to breakage due to excessive tension.

In addition, in order to solve the above problems, the present invention includes a processing tank that dyes the raw film with a dichroic material and uniaxially stretches it, an oven that dries the raw film treated in the processing tank to produce a polarizer, and A polarizing film manufacturing apparatus comprising a bonding roll for bonding a polarizer and a protective film together, and a first tension cut roll disposed between the processing tank and the bonding roll and conveying the polarizer, between the processing tank and the bonding roll. and a tension meter disposed downstream of the first tension cut roll, and a control device, wherein the control device adjusts the peripheral speed of the first tension cut roll so that the tension measured by the tension meter is a predetermined value. It is also provided as a manufacturing device for controlling a polarizing film.

Furthermore, in order to solve the above problems, the present invention is also provided as a control system used in the manufacturing apparatus of the polarizing film, which includes the tensiometer and the control device.

According to the present invention, even if the moisture content of the polarizer on the oven exit side is low, it is possible to stabilize the conveyance of the polarizer between the processing tank and the bonding roll.

1 is a diagram schematically showing a schematic configuration example of a polarizing film manufacturing apparatus to which the polarizing film manufacturing method according to an embodiment of the present invention is applied.
FIG. 2 is a diagram illustrating in more detail the portion related to the control system among the polarizing film manufacturing apparatus shown in FIG. 1 .
FIG. 3 is a diagram schematically showing a schematic configuration example of a manufacturing apparatus and a control system used in a conventional roll-to-roll method of manufacturing a polarizing film.

Hereinafter, a polarizing film manufacturing method, a polarizing film manufacturing apparatus, and a control system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In addition, in this specification, the numerical range expressed by "lower limit value When multiple numerical ranges are described separately, an arbitrary lower limit value and an arbitrary upper limit value can be selected to set “an arbitrary lower limit value to an arbitrary upper limit value.”

In addition, it should be noted that each drawing is for reference only, and that the dimensions, scale, and shape of members shown in each drawing may be different from the actual ones.

In addition, in the following description, "the manufacturing method of a polarizing film" and "the manufacturing apparatus of a polarizing film" may be simply referred to as the "manufacturing method" and the "manufacturing apparatus", respectively.

1 is a diagram schematically showing a schematic configuration example of a polarizing film manufacturing apparatus to which the polarizing film manufacturing method according to the present embodiment is applied. FIG. 2 is a diagram showing more specifically the part related to the control system according to the present embodiment among the polarizing film manufacturing apparatus shown in FIG. 1. The arrows shown in FIGS. 1 and 2 mean the conveyance direction of each film.

As shown in FIG. 1 or FIG. 2 , the manufacturing apparatus according to the present embodiment includes a series of steps from manufacturing the polarizer (F1) to at least attaching the protective film (F2) to obtaining the polarizing film (F). It is a roll-to-roll manufacturing device performed on two manufacturing lines. The manufacturing apparatus according to the present embodiment includes a processing tank (2) for dyeing the raw film (F0) with a dichroic substance and uniaxially stretching the raw film (F0), and drying the raw film (F0) treated in the processing tank (2). It is disposed between an oven 3 for producing the polarizer F1, a bonding roll 7 for bonding the polarizer F1 and the protective film F2, and the processing tank 2 and the bonding roll 7, and the polarizer It is provided with a first tension cut roll 20 that conveys (F1). The first tension cut roll 20 of this embodiment is arranged in plural numbers. Specifically, as shown in FIG. 2, as the first tension cut roll 20, there are three first tension cut rolls 20a to 20c in order from the downstream side (downstream side in the conveyance direction of the polarizer F1). This is arranged. The first tension cut rolls 20 of this embodiment are all nip rolls.

However, the present invention is not limited to this, and two or four or more first tension cut rolls 20 may be arranged, or only one first tension cut roll 20 may be arranged. Additionally, the first tension cut roll 20 may be another type of roll such as a suction roll.

Additionally, the manufacturing apparatus according to the present embodiment is provided with a tension meter 30 disposed between the processing tank 2 and the bonding roll 7 and on the downstream side of the first tension cut roll 20. The tension meters 30 of this embodiment are arranged in plural numbers (the same number as the first tension cut roll 20). Specifically, as shown in FIG. 2, as the tension meter 30, three tension meters 30a to 30c are arranged in order from the downstream side. This is because three first tension cut rolls 20 are arranged. More specifically, three tension meters 30a to 30c are arranged alternately with three first tension cut rolls 20a to 20c. That is, the tension meter 30a is disposed on the downstream side of the first tension cut roll 20a, and the tension meter 30b is located on the downstream side of the first tension cut roll 20b (of the first tension cut roll 20a). upstream side), and the tension meter 30c is disposed on the downstream side of the first tension cut roll 20c (upstream side of the first tension cut roll 20b).

As the tensiometer 30, for example, a micro-deviation tension detector "LX-100TD" manufactured by Mitsubishi Electric Corporation that uses a micro-displacement method as a measurement principle can be used.

Additionally, the manufacturing device according to this embodiment is provided with a control device 40. The control device 40 is comprised of a computer or PLC (Programmable Logic Controller).

Additionally, the manufacturing apparatus according to the present embodiment is provided with an encoder 70 that measures the rotation speed of the first tension cut roll 20c disposed on the exit side of the treatment tank 2.

The control system 100 according to the present embodiment is configured to include the tensiometer 30, control device 40, and encoder 70 described above.

Additionally, the manufacturing apparatus according to the present embodiment is provided with a second tension cut roll 60 for transporting the raw film F0 in the processing tank 2. The second tension cut roll 60 of this embodiment is arranged in plural numbers. Specifically, as shown in FIG. 2, as the second tension cut roll 60, there are five second tension cut rolls 60a to 60e in order from the upstream side (upstream side in the conveyance direction of the raw film F0). ) is placed. For convenience of illustration, the configuration of the treatment tank 2 in FIG. 2 is simplified and shown as a single tank, but in reality, the treatment tank 2 of the present embodiment is a swelling treatment tank in order from the upstream side. It is composed of five tanks divided into a dyeing treatment tank, a cross-linking treatment tank, a stretching treatment tank, and a washing treatment tank, and the second tension cut roll (60a) is located at the entrance of the swelling treatment tank, and the second tension cut roll (60b) is used for dyeing. At the entrance of the treatment tank, a second tension cut roll (60c) is at the entrance of the crosslinking treatment tank, a second tension cut roll (60d) is at the entrance of the stretching treatment tank, and a second tension cut roll (60e) is at the entrance of the washing treatment tank. Each is placed. The second tension cut rolls 60 of this embodiment are all nip rolls.

However, the present invention is not limited to this, and 2, 3, 4, or 6 or more second tension cut rolls 60 may be arranged, and only one second tension cut roll 60 may be used. It may be placed. Additionally, the second tension cut roll 60 may be another type of roll such as a suction roll.

In addition to the components described above, the manufacturing device according to the present embodiment includes various conventionally known components included in a general polarizing film manufacturing device.

When manufacturing the polarizing film (F) using the manufacturing apparatus related to this embodiment described above, first, the raw film (F0) wound on the feeding roll (1) is fed, and then fed into the processing tank (2) (this embodiment) In this case, the raw film (F0) is immersed in a treatment bath (consisting of a swelling treatment tank, a dyeing treatment tank, a crosslinking treatment tank, a stretching treatment tank, and a washing treatment tank) in order from the upstream side of the conveyance direction of the raw film (F0), and iodine or dichroic dye is added to the raw film (F0). It is uniaxially stretched along with dyeing with a dichroic material such as Next, the polarizer (F1) is obtained by drying in the oven (3). The polarizer (F1) is an optical element that has the property of transmitting light (polarized light) vibrating in only one specific direction and blocking light vibrating in other directions. The polarizer (F1) of this embodiment is in the form of a flexible film.

The raw film (F0) is in the shape of a long strip. In this specification, a long strip shape means a rectangular shape in which the length in the longitudinal direction is sufficiently larger than the length in the width direction (the direction perpendicular to the longitudinal direction). The length of the long strip in the longitudinal direction is, for example, 10 m or more, and is preferably 50 m or more.

The raw film (F0) is not particularly limited, but is preferably a film containing a hydrophilic polymer film (for example, a polyvinyl alcohol-based film, etc.) because it has excellent dyeing properties with a dichroic substance. , more preferably, a hydrophilic polymer film is used. A film containing a hydrophilic polymer film may include a film in which a hydrophilic polymer film and a non-hydrophilic polymer film are laminated. In this case, it is preferable that a hydrophilic polymer film is laminated on the front and/or back side of the non-hydrophilic polymer film. In this case, the hydrophilic polymer film laminated on the front and/or back surface of the non-hydrophilic polymer film may be a thin film with a thickness of several micrometers.

The hydrophilic polymer film is not particularly limited, and conventionally known films can be used. Specifically, hydrophilic polymer films include, for example, polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, polyethylene terephthalate (PET) films, ethylene-vinyl acetate copolymer-based films, and partially saponified films thereof. Films, etc. can be mentioned. In addition to these, polyene-oriented films such as dehydrated PVA and dechlorinated polyvinyl chloride-treated products, and stretched-oriented polyvinylene-based films can also be used. Among these, PVA-based polymer films are preferable because they are particularly excellent in dyeing properties with dichroic substances.

Raw material polymers for PVA-based polymer films include, for example, a polymer obtained by polymerizing vinyl acetate and then saponifying it, a polymer copolymerizing vinyl acetate with a small amount of copolymerizable monomers such as unsaturated carboxylic acid or unsaturated sulfonic acid, etc. You can. The degree of polymerization of the PVA-based polymer is not particularly limited, but is preferably 500 to 10,000, more preferably 1,000 to 6,000 from the viewpoint of solubility in water. Moreover, the saponification degree of the PVA-based polymer is preferably 75 mol% or more, more preferably 98 mol% to 100 mol%.

The thickness of the untreated raw film (F0) is not particularly limited, but is, for example, 15 μm to 110 μm.

As described above, the processing tank 2 of the present embodiment is composed of a swelling treatment tank, a dyeing treatment tank, a crosslinking treatment tank, a stretching treatment tank, and a washing treatment tank, in that order from the upstream side in the conveyance direction of the raw film F0. Each group has a structure described below, for example.

＜Swelling treatment tank＞

The swelling treatment tank is a treatment tank in which the swelling treatment liquid is accommodated. The swelling treatment liquid swells the raw film (F0). As the swelling treatment liquid, for example, water can be used. Additionally, water to which an appropriate amount of an iodine compound such as glycerin or potassium iodide has been added may be used as the swelling treatment liquid. When adding glycerin, the concentration is preferably 5% by weight or less, and when adding an iodine compound such as potassium iodide, the concentration is preferably 10% by weight or less.

＜Dyeing treatment tank＞

The dyeing treatment tank is a treatment tank in which the dyeing treatment liquid is accommodated. The dyeing treatment liquid dyes the raw film (F0). Examples of the dyeing treatment liquid include a solution containing a dichroic substance as an active ingredient. Examples of dichroic substances include iodine and organic dyes. Preferably, a solution in which iodine is dissolved in a solvent can be used as the dyeing treatment solution. As a solvent, water is generally used, but an organic solvent compatible with water may be additionally added. The concentration of iodine in the dyeing treatment liquid is not particularly limited, but is preferably 0.01% by weight to 10% by weight, more preferably 0.02% by weight to 7% by weight, and more preferably 0.025% by weight to 5% by weight. It is more desirable. In order to further improve dyeing efficiency, an iodine compound may be added to the dyeing treatment liquid as needed. Iodine compounds are compounds containing iodine and elements other than iodine in the molecule, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, and iodide. Tin, titanium iodide, etc. can be mentioned.

＜Cross-linking treatment tank＞

The crosslinking treatment tank is a treatment tank in which the crosslinking treatment liquid is accommodated. The crosslinking treatment liquid crosslinks the dyed raw film (F0). As the crosslinking treatment liquid, a solution containing a boron compound as an active ingredient can be used. For example, a solution in which a boron compound is dissolved in a solvent can be used as the crosslinking treatment liquid. As a solvent, water is generally used, but an organic solvent compatible with water may be additionally added. Examples of boron compounds include boric acid and borax. The concentration of the boron compound in the crosslinking treatment liquid is not particularly limited, but is preferably 1% by weight to 10% by weight, more preferably 2% by weight to 7% by weight, and even more preferably 2% by weight to 6% by weight. desirable. Additionally, since a polarizer with uniform optical properties can be obtained, an iodine compound may be added to the crosslinking treatment liquid as needed.

＜Stretching treatment tank＞

The stretching treatment tank is a treatment tank in which the stretching treatment liquid is accommodated.

The stretching treatment liquid is not particularly limited, but for example, a solution containing a boron compound as an active ingredient can be used. As the stretching treatment liquid, for example, a solution obtained by dissolving a boron compound and, if necessary, various metal salts, zinc compounds, etc. in a solvent can be used. As a solvent, water is generally used, but an organic solvent compatible with water may be additionally added. The concentration of the boron compound in the stretching treatment liquid is not particularly limited, but is preferably 1% by weight to 10% by weight, and more preferably 2% by weight to 7% by weight. From the viewpoint of suppressing elution of iodine adsorbed on the film, an iodine compound may be added to the stretching treatment liquid as needed.

＜Washing treatment tank＞

The washing treatment tank is a treatment tank in which the washing treatment liquid is accommodated. The cleaning treatment liquid cleans the raw film (F0) after stretching. The cleaning treatment liquid is a treatment liquid for washing treatment liquids such as dyeing treatment liquid and crosslinking treatment liquid adhering to the raw film (F0). As the cleaning liquid, water such as ion-exchanged water, distilled water, and pure water is typically used.

The oven 3 is formed on the downstream side of the cleaning treatment tank that constitutes the treatment tank 2 described above. The oven 3 is formed to dry the film after processing.

In addition, the treatment tank 2 of the present embodiment has a swelling treatment tank, a dyeing treatment tank, a crosslinking treatment tank, a stretching treatment tank, and a washing treatment tank, but one or two of these treatment tanks may be omitted. On the other hand, the treatment tank 2 may additionally have an adjustment treatment tank (not shown). The adjustment treatment tank is a treatment tank in which the adjustment treatment liquid is accommodated. This conditioning treatment tank is formed between the crosslinking treatment tank and the stretching treatment tank, or between the stretching treatment tank and the washing treatment tank. The adjustment treatment liquid is a solution for color adjustment of the film, etc., and a solution containing an iodine compound as an active ingredient can be used.

The film obtained by drying the raw film (F0) after washing in the oven (3) is the polarizer (F1).

The thickness of the polarizer F1 on the exit side of the oven 3 is not particularly limited, but for example, when it is 20 μm or less, the manufacturing method according to the present embodiment is preferably used.

In addition, the moisture content of the polarizer (F1) on the exit side of the oven 3 is not particularly limited, but when it is 15% or less, the manufacturing method according to the present embodiment is preferably used. For example, when the drying temperature in the oven 3 is 60°C or higher and the drying time is 30 seconds or longer, the moisture content of the polarizer F1 on the exit side of the oven 3 is likely to be 15% or less.

In addition, the polarizer (F1) for which the present invention is preferably used is not limited to a polarizer obtained by stretching a film single layer, and also includes a polarizer obtained by stretching a laminated film coated with a PVA-based resin on a base material.

Representative examples of the above polarizer include Japanese Patent Application Laid-Open No. 51-069644, Japanese Patent Application Publication No. 2000-338329, International Publication No. 2010/100917, Japanese Patent Application Publication No. 2014-059328, and Japanese Patent Application Publication No. 2000-338329. A thin polarizing film described in 2012-73563 is included. These thin polarizing films can be obtained by a manufacturing method including the process of stretching the PVA-based resin layer and the resin substrate for stretching in the state of a laminate and the process of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it becomes possible to stretch without problems such as breakage during stretching because it is supported by the resin base material for stretching.

Next, as shown in FIG. 1, an active energy ray-curable adhesive is applied to both surfaces of the polarizer F1 using a coating machine 6. In this embodiment, a gravure coater is used as the coating machine 6. Additionally, an active energy ray-curable adhesive is applied to one side of the protective film (F2) fed from the feeding roll (5) using the coating machine (6). Then, the adhesive-coated protective film (F2) is bonded to both sides of the adhesive-coated polarizer (F1) using the bonding roll 7.

As the adhesive applied by the coating machine 6, an active energy ray-curable adhesive is used.

As an active energy ray-curable adhesive, a conventionally known adhesive can be used. Active energy ray-curable adhesives generally contain an active energy ray-curable component and a polymerization initiator, and, if necessary, various additives.

Active energy ray curable components can be broadly divided into electron beam curable properties, ultraviolet ray curable properties, and visible light curable properties. In addition, active energy ray-curable components can be roughly divided into radically polymerizable compounds and cationically polymerizable compounds from the viewpoint of the curing mechanism.

Examples of the radically polymerizable compound include compounds having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acryloyl group and a vinyl group. Additionally, either a monofunctional radically polymerizable compound or a bifunctional or more polyfunctional radically polymerizable compound can be used. In addition, these radically polymerizable compounds may be used individually or in combination of two or more types. As the radically polymerizable compound, a compound having a (meth)acryloyl group is preferable, for example, a (meth)acrylamide derivative having a (meth)acrylamide group, (meth)acryloyloxy group having a (meth)acryloyloxy group. Acrylates, etc. can be mentioned.

When using a radically polymerizable compound as an active energy ray-curable adhesive, the polymerization initiator is appropriately selected depending on the active energy ray. When curing the adhesive with ultraviolet rays or visible rays, a polymerization initiator for ultraviolet ray cleavage or visible ray cleavage is used. Examples of such polymerization initiators include benzophenone-based compounds, aromatic ketone compounds, acetophenone-based compounds, aromatic ketal-based compounds, aromatic sulfonyl chloride-based compounds, and thioxanthone-based compounds.

Examples of the cationically polymerizable compound include monofunctional cationically polymerizable compounds having one cationically polymerizable functional group in the molecule, polyfunctional cationically polymerizable compounds having two or more cationically polymerizable functional groups in the molecule, etc. there is. Examples of the cationically polymerizable functional group include an epoxy group, oxetanyl group, and vinyl ether group. Cationically polymerizable compounds having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. Cationically polymerizable compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3- Ethyl-3-(phenoxymethyl)oxetane, etc. can be mentioned. Cationically polymerizable compounds having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

When using a cationically polymerizable compound as an active energy ray-curable adhesive, a cationic polymerization initiator is blended. This cationic polymerization initiator generates cationic species or Lewis acids by irradiation of active energy rays such as visible light, ultraviolet rays, and electron beams, and initiates a polymerization reaction with the epoxy group of the cationically polymerizable compound. As the cationic polymerization initiator, a photoacid generator and a photobase generator can be used.

In the present invention, an active energy ray-curable adhesive that is cured with light containing visible light of 380 nm to 450 nm can also be used. In this case, it is preferable to use an active energy ray-curable adhesive containing a radically polymerizable compound and a polymerization initiator.

Such an active energy ray-curable adhesive is disclosed in, for example, Japanese Patent Application Publication No. 2018-092186, and the active energy ray-curable adhesive described in the above-mentioned publication can be used as the active energy ray-curable adhesive of the present invention. In this specification, for reasons of space, the description of the above-mentioned publication is omitted, but the description of the adhesive in the above-mentioned publication is accepted as is in this specification.

The coating thickness of the adhesive is not particularly limited, but if it is too small, the adhesive strength of the film decreases, and if it is too large, the thickness of the polarizing film (F) becomes relatively too large. From this viewpoint, it is preferable that the coating thickness of the adhesive for the polarizer (F1) and the protective film (F2) is each independently 0.1 μm to 5 μm.

In addition, the viscosity of the adhesive at the start of application is not particularly limited, but if it is too small or too large, the adhesiveness of the adhesive will decrease from the start of application. From this point of view, the viscosity of the adhesive at 25°C at the start of application is preferably adjusted to 1 mPa·s to 100 mPa·s, and the viscosity at 25°C at the start of application is 10 mPa·s to 50 mPa·s. It is more preferable that it is adjusted to mPa·s, and it is especially preferable that it is adjusted to 15 mPa·s to 45 mPa·s.

The protective film (F2) is in the shape of a long strip. In addition, the protective film (F2) is a film (having hydrophobicity) with lower hydrophilicity than the polarizer (F1). The protective film (F2) preferably has excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetylcellulose and triacetylcellulose, acrylic polymers such as polymethyl methacrylate, polystyrene and acrylonitrile-styrene copolymers. Styrene-based polymers such as (AS resin) and polycarbonate-based polymers can be mentioned. In addition, polyolefin-based polymers such as polyethylene, polypropylene, polyolefins with cyclo- or norbornene structures, ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, and alcohol. Phone-based polymer, polyether sulfone-based polymer, polyether ether ketone-based polymer, polyphenylene sulfide-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, arylate-based polymer, polyoxymethylene-based polymer, Epoxy-based polymers or blends of the above polymers can also be cited as examples of polymers that form the protective film (F2). The protective film (F2) may contain one or more types of arbitrary appropriate additives. Additives include, for example, ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, discoloration inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The content of the thermoplastic resin in the protective film (F2) is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, further preferably 60 to 98% by weight, particularly preferably 70 to 97% by weight. It is weight%. If the content of the thermoplastic resin in the protective film (F2) is 50% by weight or less, there is a risk that the thermoplastic resin may not be able to sufficiently exhibit the inherent high transparency.

In addition, the protective film (F2) includes polymer films described in Japanese Patent Application Laid-Open No. 2001-343529, such as (A) a thermoplastic resin having a substituted and/or unsubstituted imide group in the side chain, and and a resin composition containing a thermoplastic resin having substituted and/or unsubstituted phenyl and nitrile groups. Specific examples include films of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. As the film, a film made of a mixed extrusion product of a resin composition, etc. can be used. These films have a small phase difference and a small photoelastic coefficient, so they can solve problems such as unevenness due to deformation of the polarizing film (F), and also have a low moisture permeability, so they are excellent in humidification durability.

Next, as shown in FIG. 1, the adhesive between the polarizer (F1) and the protective film (F2) is cured by irradiating active energy rays from the active energy ray irradiation device 8, and then dried in the oven 9. The active energy ray is appropriately selected depending on the curability of the active energy ray-curable adhesive. Examples of active energy rays include electron beams, ultraviolet rays, and visible rays. Finally, the long strip-shaped surface protection film (F3) fed from the feeding roll 10 is bonded to one side of the polarizer (F1) with the protective film (F2) bonded on both sides by the bonding roll 11, thereby forming a long strip. A strip-shaped polarizing film (F) is obtained. The obtained polarizing film (F) is wound by the winding roll 12.

In addition, in the example shown in FIG. 1, the active energy ray hardening type adhesive is applied to both the polarizer (F1) and the protective film (F2), but it is also possible to apply the adhesive only to both surfaces of the polarizer (F1). In this case, among the total of four coating machines 6 shown in FIG. 1, the two coating machines 6 on the lower side (downstream side in the conveyance direction of the polarizer F1) in FIG. 1 are unnecessary. Additionally, it is also possible to apply the adhesive only to one side of the protective film (F2). In this case, among the total of four coating machines 6 shown in FIG. 1, the two coating machines 6 on the upper side (upstream side of the conveyance direction of the polarizer F1) in FIG. 1 are unnecessary. In addition, in the example shown in FIG. 1, since the protective film (F2) is bonded to both sides of the polarizer (F1), a pair of coaters 6 are arranged on the left and right sides of FIG. 1, and the active energy ray irradiation device 8 ) are arranged in pairs on the left and right, but in the case where the protective film (F2) is bonded only to one side of the polarizer (F1), the coating machine (6) and the active energy ray irradiation device (8) are placed on either the left or right side of FIG. You can place only 1.

Hereinafter, the operation of the control system 100 related to this embodiment will be described.

The control device 40 provided in the control system 100 controls the peripheral speed of the first tension cut roll 20 so that the tension measured by the tension meter 30 is a predetermined value (the first tension cut roll 20 of the present invention) equivalent to a controlled process). Specifically, while manufacturing the polarizing film F, the tensiometer 30 always measures the tension of the polarizer F1 and outputs the tension to the control device 40. And, as shown in FIG. 2, the control device 40 adjusts the tension of the first tension cut roll 20a so that the tension Ta input from the tension meter 30a disposed at the most downstream side becomes a predetermined value. Control the peripheral speed (constant tension control). Specifically, when the input tension Ta is smaller than the value predetermined and stored in the control device 40, the peripheral speed of the first tension cut roll 20a is set to a peripheral speed ( A control signal is transmitted to the drive unit (motor not shown, etc.) of the first tension cut roll 20a so that P1a). Conversely, when the input tension Ta is larger than the value predetermined and stored in the control device 40, the first tension cut roll (20a) is adjusted so that the peripheral speed of the first tension cut roll 20a becomes a small peripheral speed P1a A control signal is transmitted to the driving unit of 20a).

Next, the control device 40 adjusts the first tension cut roll 20b so that the tension Tb input from the tension meter 30b located immediately upstream of the tension meter 30a becomes a predetermined value. Control the peripheral speed (constant tension control). Specifically, when the input tension Tb is smaller than the value predetermined and stored in the control device 40, the control device 40 sets the peripheral speed of the first tension cut roll 20b to a peripheral speed greater than the current point ( A control signal is transmitted to the drive unit (motor not shown, etc.) of the first tension cut roll 20b so that P1b). Conversely, when the input tension Tb is greater than the value predetermined and stored in the control device 40, the first tension cut roll ( 20b) A control signal is transmitted to the driving unit.

Finally, the control device 40 controls the first tension cut roll disposed on the output side of the treatment tank 2 so that the tension Tc input from the tension meter 30c disposed at the most upstream side becomes a predetermined value. (20c) Control the peripheral speed (constant tension control). Specifically, when the input tension Tc is smaller than the value predetermined and stored in the control device 40, the control device 40 sets the peripheral speed of the first tension cut roll 20c to a peripheral speed greater than the current point ( A control signal is sent to the drive unit (motor, etc., not shown) of the first tension cut roll 20c so that P1c). Conversely, when the input tension Tc is greater than the value predetermined and stored in the control device 40, the first tension cut roll ( 20c) A control signal is transmitted to the driving unit.

As described above, in the control system 100 according to the present embodiment, in the first control process, the tension measured by the tension meter 30 disposed downstream of the first tension cut roll 20 is a predetermined value. To achieve this, the peripheral speed of the first tension cut roll 20 is controlled. In other words, since the circumferential speed of the first tension cut roll 20 is controlled so that the actually measured tension becomes a predetermined value, even if the moisture content of the polarizer F1 on the exit side of the oven 3 is low, the moisture content actually occurring in the polarizer F1 is reduced. The fluctuation in tension becomes small, making it possible to stabilize the transport of the polarizer F1.

In addition, the control system 100 according to the present embodiment controls the peripheral speed P1a by the combination of the tension meter 30a and the first tension cut roll 20a disposed at the most downstream side in the first control process. After executing the control, the peripheral speed is sequentially directed to the combinations arranged on the upstream side until the peripheral speed P1c is controlled by the combination of the tension meter 30c and the first tension cut roll 20c arranged on the most upstream side. Execute control. For this reason, control does not diverge and stable peripheral speed control is possible.

The control system 100 according to this embodiment measures the peripheral speed of the first tension cut roll 20c disposed on the exit side of the treatment tank 2 after executing the first control process described above, and measures the measured circumferential speed of the first tension cut roll 20c. The peripheral speed of the second tension cut roll 60 is controlled so that the ratio of the peripheral speed P1c' of the first tension cut roll and the peripheral speed of the second tension cut roll 60 is a predetermined value (second tension cut roll 60 of the present invention) equivalent to a controlled process). Specifically, while the polarizing film F is being manufactured, the encoder 70 always measures the rotation speed of the first tension cut roll 20c and outputs the measurement to the control device 40. The control device 40 determines the peripheral speed of the first tension cut roll 20c ( Calculate P1c'). And, as shown in FIG. 2, the control device 40 sets the ratio of the peripheral speed P1c' of the first tension cut roll 20c and the peripheral speed of the second tension cut roll 60 to a predetermined value, The peripheral speed of the second tension cut roll 60 is controlled (ratio constant control). Specifically, the peripheral speed of the second tension cut roll 60a is P2a, the peripheral speed of the second tension cut roll 60b is P2b, the peripheral speed of the second tension cut roll 60c is P2c, and the peripheral speed of the second tension cut roll 60c is P2c. ) If the peripheral speed of the second tension cut roll 60e is P2d and the peripheral speed of the second tension cut roll 60e is P2e, the control device 40 has P2a/P1c' = β1, P2b/P1c' = β2, P2c/P1c' = β3, P2d. The peripheral speeds (P2a, P2b, P2c, P2d, and P2e) are determined so that /P1c' = β4, P2e/P1c' = β5 (β1, β2, β3, β4, and β5 are predetermined integers), and each peripheral speed (P2a ~ A control signal is transmitted to the driving unit (motor, etc., not shown) of the second tension cut rolls 60a to 60e so that the second tension cut rolls 60a to 60e rotate respectively at P2e).

Since the control system 100 according to the present embodiment controls the peripheral speed of the first tension cut roll 20c by constant tension control in the first control process, the first tension cut roll 20c disposed on the exit side of the treatment tank 2 Unlike the conventional case where the peripheral speed of the tension cut roll 20c is controlled by constant ratio control, the peripheral speed of the tension cut roll 20c is not constant but fluctuates.

And, in the second control process, the control system 100 according to the present embodiment basically controls the peripheral speed (P1c') measured by the first tension cut roll 20c disposed on the exit side of the treatment tank 2. ) and the peripheral speed of the second tension cut roll 60 are controlled so that the ratio of the peripheral speed of the second tension cut roll 60 is a predetermined value, that is, constant ratio control is performed. However, since the actually measured peripheral speed P1c' is used as the peripheral speed of the first tension cut roll 20c disposed on the exit side of the treatment tank 2, which serves as the standard for the ratio, the treatment tank 2 ) Even if the peripheral speed (P1c') of the first tension cut roll (20c) disposed on the exit side of do.

Example

Hereinafter, examples and comparative examples will be described to describe the present invention in more detail. However, the present invention is not limited to the following examples.

<Example>

As the raw film (F0), a 45-μm-thick polyvinyl alcohol film (VF-PS-4500 manufactured by Kuraray Co., Ltd.) with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% was used, and treatment was performed in the treatment tank 2. Specifically, in the treatment tank 2, it was immersed in warm water at 30°C for 60 seconds to swell. Next, it was immersed in an aqueous solution of iodine/potassium iodide (weight ratio = 0.5/8) at a concentration of 0.3%, and the film was dyed while being stretched up to 3.5 times. After that, stretching was performed in a boric acid ester aqueous solution at 65°C so that the total stretching ratio was 6 times. After performing the above treatment in the treatment tank 2, drying was performed in the oven 3 at a drying temperature of 40°C for 3 minutes to obtain a PVA-based polarizer (F1) with a thickness of 18 μm.

The moisture content of this polarizer (F1) at the exit side of the oven 3 was measured and found to be 14%.

The moisture content of the polarizer (F1) was measured as follows.

About 60 minutes after starting the device, an arbitrary point of the polarizer F1 immediately after coming out of the oven 3 was cut into a square shape to obtain a sample piece. The weight of the cut sample piece was quickly measured under standard conditions. After that, the sample piece was forcibly dried at 120°C for 2 hours using a heating oven, and then the weight of the sample piece was quickly measured under standard conditions. In addition, it is thought that the moisture contained in the sample piece has almost disappeared due to this forced drying.

By substituting the weight of the sample piece before forced drying (the weight of the polarizer (F1) after drying) and the weight of the sample piece after forced drying (the weight of the polarizer (F1) after complete drying) into the following equation, the moisture content of the polarizer (F1) is calculated. Saved.

Moisture content of polarizer (F1) = (Weight of polarizer (F1) after drying - Weight of polarizer (F1) after complete drying)/Weight of polarizer (F1) after drying × 100

In the embodiment, as shown in FIGS. 1 and 2, when transporting the polarizer F1, it is disposed between the processing tank 2 and the bonding roll 7 and on the downstream side of the first tension cut roll 20. Constant tension control was performed to control the peripheral speed of the first tension cut roll 20 so that the tension measured with the tensiometer 30 was a predetermined value, and the presence or absence of fracture of the polarizer F1 was investigated. Additionally, fluctuations in tension measured with the tensiometer 30a shown in FIG. 2 were investigated. In addition, even if the variation in tension is measured with the tensiometers 30b and 30c, the amount of variation is the same as when measured with the tensiometer 30a.

＜Comparative example＞

In the comparative example, when transporting the polarizer F1, the ratio of the peripheral speed of the bonding roll 7 and the peripheral speed of the first tension cut roll 20 disposed between the processing tank 2 and the bonding roll 7 is Under the same conditions as in the example, except that ratio constant control was performed to control the peripheral speed of the first tension cut roll 20 so that it was a predetermined value, the presence or absence of fracture of the polarizer F1 and the tension meter 30a ) The fluctuations in tension measured were investigated.

The results of the above tests are shown in Table 1.

As shown in Table 1, in the comparative example, the tension fluctuation was very large, and fracture of the polarizer (F1) occurred within 1 hour from the start of conveyance.

In contrast, in the examples, the tension fluctuation was small and the polarizer (F1) did not break.

F0 ; raw film
F1 ; polarizer
F2 ; protective film
F ; polarizing film
2 ; treatment tank
3 ; Oven
7 ; glue roll
20, 20a, 20b, 20c ; 1st tension cut roll
30, 30a, 30b, 30c; tensiometer
40 ; controller
60, 60a, 60b, 60c, 60d, 60e ; 2nd tension cut roll
70 ; encoder
100 ; control system

Claims (7)

A method of manufacturing a polarizing film by dyeing the raw film with a dichroic material in a treatment tank and stretching it uniaxially, drying it in an oven to produce a polarizer, and bonding the polarizer and the protective film with a bonding roll,
A plurality of first tension cut rolls for conveying the polarizer are arranged between the processing tank and the bonding roll, and a plurality of tension meters are alternately arranged between the processing tank and the bonding roll and on the downstream side of the first tension cut roll,
A first control process for controlling the peripheral speed of the first tension cut roll so that the tension measured by the tension meter is a predetermined value,
In the first control process, after controlling the peripheral speed by the combination of the tension meter and the first tension cut roll disposed at the most downstream side, the roll disposed upstream of the combination disposed at the most downstream side Controlling the peripheral speed by a combination of the tension meter and the first tension cut roll is sequentially performed toward the upstream side,
Method for producing polarizing film. According to claim 1,
The first tension cut roll is disposed on an exit side of the processing tank, and a second tension cut roll is disposed for conveying the raw film in the processing tank,
After executing the first control process, the peripheral speed of the first tension cut roll disposed on the exit side of the treatment tank is measured, and the ratio of the measured peripheral speed of the first tension cut roll and the peripheral speed of the second tension cut roll Including a second control process of controlling the peripheral speed of the second tension cut roll so that it reaches this predetermined value,
Method for producing polarizing film. According to claim 1,
The moisture content of the polarizer at the exit side of the oven is 15% or less,
Method for producing polarizing film. According to claim 1,
The thickness of the polarizer at the exit side of the oven is 20 μm or less,
Method for producing polarizing film. A processing tank for dyeing a raw film with a dichroic material and uniaxially stretching it, an oven for drying the raw film processed in the processing tank to produce a polarizer, a bonding roll for bonding the polarizer and a protective film, and the processing. A polarizing film manufacturing apparatus comprising a first tension cut roll disposed between a tank and the bonding roll and transporting the polarizer,
a tension meter disposed between the treatment tank and the bonding roll and downstream of the first tension cut roll;
Equipped with a control device,
A plurality of the first tension cut rolls and the tension gauge are arranged alternately,
The control device controls the peripheral speed of the first tension cut roll so that the tension measured by the tension meter is a predetermined value,
The control device performs control of the peripheral speed by the combination of the tension meter and the first tension cut roll arranged on the most downstream side, and then controls the tension meter arranged on the upstream side of the combination arranged on the most downstream side. and sequentially performing control of the circumferential speed toward the upstream side by a combination of the first tension cut rolls.
Equipment for manufacturing polarizing films. The tensiometer,
Equipped with the control device,
A control system used in the manufacturing apparatus of the polarizing film according to claim 5. delete

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