KR20220016893A - Optical film manufacturing method and optical film manufacturing apparatus - Google Patents

Abstract

The manufacturing method of the optical film 4 according to an embodiment of the present invention is a method of manufacturing an optical film by subjecting a long film 2 to N treatments (N is an integer greater than or equal to 1), N processing is performed while conveying the film, and during conveyance, the width of the film is continuously measured at each of the plurality of locations 20, and the measurement result at the upstream location among the two locations selected from the plurality of locations and the downstream location The rate of change of the width of the film is calculated based on the measurement result obtained at the same timing among the measurement results in the film.

Description

Optical film manufacturing method and optical film manufacturing apparatus

The present invention relates to a method for manufacturing an optical film and an apparatus for manufacturing an optical film.

An optical film is manufactured by performing at least 1 process for providing a desired optical characteristic, conveying a film normally. For example, when the optical film is a polarizing film, at least one treatment for imparting a linearly polarizing property to the film as an optical property is performed. In the case of manufacturing the optical film as described above, the width of the film is changed in the process of manufacturing the optical film from the film. When a film is conveyed, the change rate of the width of an upstream film width and a downstream film width is known as a neck-in rate (refer patent document 1). The manufacturing process of an optical film WHEREIN: When the neck-in rate of a film deviates from the preset allowable range (management width), a film may fracture|rupture or the thickness of a film may shift|deviate from desired thickness. Therefore, in order to manufacture an optical film suitably, management of a neck-in rate is important.

Patent Document 1: Japanese Patent Laid-Open No. Hei 8-226811

In the technique of patent document 1, in order to compute a neck-in rate, the width|variety of a film is measured at an upstream measuring point and a downstream measuring point. However, in Patent Document 1, in the upstream measurement point and the downstream measurement point, the same location of the film (web in Patent Literature 1), that is, the location of the film measured at the upstream measurement point, passes the downstream measurement point. The width of the film is measured at the downstream measurement point. Therefore, while the film moves from the upstream measurement point to the downstream measurement point, it cannot be confirmed whether the neck-in rate is out of the allowable range.

Then, an object of this invention is to provide the manufacturing method of the optical film which can measure a neck-in rate efficiently, quality is stable, and can reduce material cost, and the manufacturing apparatus of an optical film.

The method for manufacturing an optical film according to an aspect of the present invention is a method of manufacturing an optical film by performing N treatments (N is an integer greater than or equal to 1) on a long film, wherein the N treatments are performed while conveying the film is carried out, during the conveyance, the width of the film is continuously measured at each of a plurality of locations, and obtained at the same timing among the measurement results at the upstream location and the measurement results at the downstream location among the two locations selected from the plurality of locations Based on the measurement result, the change rate of the width|variety of the said film is computed.

An apparatus for manufacturing an optical film according to another aspect of the present invention includes: N processing units (N is an integer of 1 or more) for performing a process for imparting at least optical properties to a film; a conveying mechanism for conveying the film; a plurality of width measuring devices disposed at a plurality of locations on the conveying mechanism and continuously measuring the width of the film being conveyed by the conveying mechanism at each of the plurality of locations, and two width measuring devices selected from the plurality of width measuring devices A calculation unit configured to calculate a rate of change of the width of the film is provided based on the measurement result of the upstream width measurement device and the measurement result obtained at the same timing among the measurement results of the downstream width measurement device.

In the said manufacturing method and the said manufacturing apparatus, the width|variety of a film is measured at several places. Thereby, conveying a film, the width|variety of a film can be measured continuously. Moreover, the change rate of the width of a film is computed based on the measurement result of the width of the film measured at the same timing in an upstream location and a downstream location among the width|variety of the film continuously measured at several places. Therefore, a neck-in rate can be measured efficiently, quality is stable, and the material cost of an optical film can be reduced.

In the manufacturing method, the upstream location may be a position before one of the N treatments is performed, and the downstream location may be a location after the one treatment is performed.

The said manufacturing apparatus WHEREIN: The said upstream width measuring device may be arrange|positioned before one of the said N processing parts, The said downstream width measuring device may be arrange|positioned behind the said one processing part.

The width of the film tends to change when each of the N treatments is performed. Therefore, in the said structure, in the location where the width|variety of a film changes easily, the change rate of the width|variety of a film is computable.

In the manufacturing method, the N processes include an i-1 th process, an i th process, and an i+1 th process (i is an integer of 2 or more), wherein the upstream location is the position of the i-1 process and the position of the i-th process, and the downstream location may be between the position of the i-th process and the position of the i+1-th process.

In the above manufacturing apparatus, the N processing units include an i-1th processing unit, an i-th processing unit, and an i+1th processing unit (i is an integer of 2 or more), and the upstream-side width measuring unit includes the i-1th processing unit. It may be arrange|positioned between a processing part and the said ith processing part, and the said downstream width measuring device may be arrange|positioned between the said ith processing part and the said i+1th processing part.

The width of a film is easy to change when a process is given to a film. Therefore, in the said structure, in the location where the width|variety of a film changes easily, the change rate of the width|variety of a film is computable. In addition, in the above configuration, when the rate of change of the width of the film exceeds the allowable range, the rate of change of the width is due to the i-th treatment or because it is considered that the state of the film before the i-th treatment is changing, By adjusting the rate of change of the width within the allowable range, the problem can be avoided in advance.

In the above production method, the N processes include an i-1 process and an i-th process (i is an integer of 2 or more), wherein the upstream location is at a position during the i-1 process, and the downstream location may be between the position of the i-1th processing and the position of the i-th processing, and the upstream location and the downstream location may be between the position of the i-1th processing and the position of the i-th processing, respectively Alternatively, the upstream location may be at a position before the i-1 process, and the downstream location may be at a location during the i-1 process.

In the above manufacturing apparatus, the N processing units include an i-1th processing unit and an i-th processing unit (i is an integer greater than or equal to 2), the upstream width measuring device is disposed at the position of the i-1th processing unit, and Further, the downstream width measuring device may be disposed between the i-1th processing unit and the i-th processing unit, wherein the upstream side width measuring device and the downstream side width measuring unit are the i-1th processing unit and the i-th processing unit, respectively. Alternatively, the upstream width measuring device may be disposed in front of the i-1th processing unit, and the downstream side width measuring device may be disposed at the position of the i-1th processing unit.

In the above configuration, it is possible to calculate the rate of change of the width when the film is being treated, or the rate of change of the width of the film between the completion of one treatment for the film and the next treatment.

The said manufacturing method WHEREIN: You may measure the said width|variety in the said film by acquiring the image of the at least edge part of a film with an imaging part during the said conveyance.

The said manufacturing apparatus WHEREIN: At least one of the said some width measuring device may have the imaging part which images at least the edge part of the said film.

In this case, the width of the film can be calculated using the image acquired by the imaging unit.

The said manufacturing method WHEREIN: You may measure the said width|variety in the said film based on the brightness|luminance of at least one of the reflected light from the said film by the light which injects into the said film, and transmitted light during the said conveyance.

In the manufacturing apparatus, at least one of the plurality of width measuring devices may have a light detection unit for detecting at least one of reflected light and transmitted light from the film by light incident on the film.

The said manufacturing apparatus WHEREIN: At least 1 width measuring device among the said some width measuring device may have a light irradiation part which irradiates light to the said film. For example, when the difference in the luminance of the light from the surrounding environment is small when the transmitted light from the film is detected, the luminance of the surrounding environment can be increased with the light from the light irradiation unit. As a result, it is easy to measure the width of the film.

In the manufacturing method, the film is conveyed by a conveyance roll, the film on the conveyance roll is irradiated with the light, and the difference in luminance of the reflected light of the film and the conveyance roll generated by the irradiation of the light Based on it, you may measure the said width|variety in the said film by detecting the edge part of the said film.

The said manufacturing apparatus WHEREIN: The said conveyance mechanism has a conveyance roll, the said light irradiation part irradiates light to the said film on the said conveyance roll, At least one width measuring device among the said plurality of width measuring instruments is on the said conveyance roll. You may measure the width|variety of the said film based on the difference of the brightness|luminance of the reflected light of the said film and the said conveyance roll which generate|occur|produce by the light from the said light irradiation part to the said film.

In this case, it is easy to specify the edge part of a film with the difference of the brightness|luminance of the reflected light from a film, and the reflected light from a conveyance roll. As a result, the width of the film can be more accurately calculated based on the position of the end portion. When the reflected light from the film has sufficient luminance for specular reflection, the measurement is not limited to the conveyance roll.

In the manufacturing method, the transmitted light may be transmitted light from the film by light incident on the film through a polarizing filter. Or the said manufacturing method WHEREIN: You may measure the width|variety in the said film based on the brightness|luminance of the light obtained by making the said transmitted light pass through a polarizing film.

One Embodiment of the said manufacturing apparatus may have a polarizing filter between the said light irradiation part and the said film. Or one Embodiment of the said manufacturing apparatus may have a polarizing filter between the said photodetector and the said film.

For example, when the film has a linearly polarized light characteristic, it is easy to measure the width of the film by disposing the polarizing filter in a cross nicol state with the film.

In the manufacturing method, the N treatments may include at least one of swelling treatment, dyeing treatment, crosslinking treatment, stretching treatment, and drying treatment.

The said manufacturing apparatus WHEREIN: The said N processing part may contain at least any one of a swelling processing part, a dyeing|staining processing part, a crosslinking processing part, an extending|stretching process part, and a drying processing part.

An example of the said optical film is a polarizing film.

ADVANTAGE OF THE INVENTION According to this invention, the neck-in rate can be measured efficiently, quality is stable, and the manufacturing method of the optical film which can reduce material cost, and the manufacturing apparatus of an optical film can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram for demonstrating the manufacturing method of the optical film which concerns on one Embodiment.
It is a figure for demonstrating the change of the width|variety of the film in the manufacturing method of an optical film.
3 is a view for explaining a width measuring device and a calculation unit.
4 is a view for explaining an example of a width detector included in the width measuring device.
5 is a view for explaining another example of the width detector of the width measuring device.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. In the drawings, the same reference numerals are attached to the same or corresponding parts, and overlapping explanations are omitted. Dimensional ratios in the drawings do not necessarily coincide with those in the description.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram for demonstrating one Embodiment of this invention. Hereinafter, the case where a polarizing film is manufactured as an optical film is mentioned as an example and demonstrated.

In this embodiment, the polarizing film (optical film) 4 is carried out to the film 2 being conveyed in order, conveying the elongate film 2, by processing N pieces (N is an integer greater than or equal to 1) in order. manufacture The N processes are processes for imparting a linearly polarized light characteristic to the film 2 at least as an optical characteristic. The upper limit of N is not particularly limited, but N is usually an integer of 30 or less, and may be an integer of 25 or less, may be an integer of 20 or less, or may be an integer of 10 or less.

When the film 2 is provided with linearly polarized light characteristics, the film 2 functions as a polarizing film 4 . Since the linearly polarized light characteristic is substantially provided before all N processes are completed, in the manufacturing method of the polarizing film 4 using the film 2, the film 2 functions as the polarizing film 4 during the manufacturing process. has However, for convenience of explanation, unless otherwise stated, the film 2 after all of the N treatments is completed is referred to as the polarizing film 4, and the film before the N treatments are completed is all referred to as the film 2. . When manufacturing the polarizing film 4, a swelling process, a dyeing|staining process, a crosslinking process, an extending|stretching process, and a drying process are normally given to the film 2. The stretching treatment may be performed on the film 2 during any one treatment (eg, crosslinking treatment) or in parallel while performing a plurality of treatments.

The film 2 is a polyvinyl alcohol-type resin film. The example of the length of the longitudinal direction of the film 2 is 1000 m or more and 30000 m or less, Preferably it is the range of 1000 m or more and 20000 m or less. The example of the length of the width direction (direction orthogonal to a longitudinal direction) of the film 2 is 1300 mm - 5000 mm. An example of the thickness of the film 2 before N processing is performed is 10 micrometers - 100 micrometers. The film 2 can be manufactured by well-known methods, such as a melt extrusion method and a solvent casting method. The film 2 may be a purchased film or a film subjected to a process such as stretching or lamination in advance. In FIG. 1, the case where the film 2 is prepared as the raw roll 6, and the film 2 unwound from the raw roll 6 is subjected to N processing to obtain the polarizing film 4 is shown. . When the film 2 is produced by the above method (melt extrusion method, solvent casting method, etc.), for example, the film 2 produced by the above method (melt extrusion method, solvent casting method, etc.) is continuously conveyed, and the You may perform the said N processes during conveyance.

The manufacturing apparatus 10 of the polarizing film 4 includes a plurality of nip rolls 11, a plurality of guide rolls 12, a swelling treatment unit 13 ₁ , a dyeing treatment unit 13 ₂ , a crosslinking treatment unit ( _{13 3} , a washing processing unit ₁₃₄ , and a drying processing unit 135 .

The some nip roll 11 and the some guide roll 12 are contained in the conveyance mechanism of the film 2, and are conveyance rolls for conveying the film 2. The conveyance path|route of the film 2 is comprised by arrange|positioning the some nip roll 11 and the some guide roll 12 suitably.

The nip roll 11 has a function which provides the rotational force of the nip roll 11 to the film 2 by pinching|interposing the film 2 and pressing. The nip roll 11 also has a function of changing the conveyance direction of the film 2 . In the conveyance direction of the film 2 WHEREIN: The film 2 conveyed between the said two adjacent nip rolls 11 by providing a circumferential speed difference to the two adjacent nip rolls 11, for example. A stretching treatment (eg, uniaxial stretching treatment) is applied to the . 1 illustrates the case where the manufacturing apparatus 10 has eight nip rolls 11 . When the six nip rolls 11 are distinguished and demonstrated, as shown in FIG. ₁ , the _six nip rolls 11 are called nip rolls 111-116.

The guide roll 12 supports the film 2 and has a function of changing the conveyance direction of the film 2 . 1 : has illustrated the case where the manufacturing apparatus 10 has the 12 guide rolls 12. As shown in FIG. When the 12 guide rolls 12 are distinguished and described, as shown in FIG. 1 , the 12 guide rolls 12 are called guide rolls 12 ₁ to 12 ₁₂ .

The swelling processing part 13 ₁ is a part which performs a swelling process on the film 2 . The swelling processing unit 13 ₁ has a processing tank in which the processing liquid for the swelling processing is stored. A swelling process is performed to the film 2 by immersing the film 2 in the processing liquid which the swelling processing part 13 ₁ has. In this embodiment, the conveyance path|route of the film which immerses the film 2 in a process liquid is formed by the nip roll _{11 1} and the guide rolls 12 _1-12 . In this configuration, the nip roll 11 ₁ and the guide roll 12 ₃ are before and after the film 2 is subjected to the swelling treatment by the swelling treatment unit 13 ₁ (in other words, the swelling treatment unit 13 ₁ ). before and after).

The said swelling treatment is performed for the objective of the foreign material removal on the surface of the film 2, the plasticizer removal in the film 2, provision of dyeing easiness in a post process, plasticization of the film 2, etc. Conditions for the swelling treatment can be determined within a range that can achieve these objects and within a range in which problems such as extreme dissolution of the film 2 and devitrification do not occur. In the swelling treatment section 13 ₁ , the swelling treatment is performed by immersing the film 2 in, for example, a treatment liquid having a temperature of 10 to 50°C, preferably 20 to 50°C. The time of a swelling process is about 5-300 second, Preferably it is about 20-240 second. An example of the processing liquid in the swelling processing unit 13 ₁ is water. Therefore, the swelling treatment can also serve as the water washing treatment of the film 2 .

The dyeing process part 132 is a part which performs a dyeing process on the film ₂ . _The dyeing process part 132 has the process tank in which the process liquid for dyeing process was stored. A dyeing process is performed to the film ₂ by immersing a film in the process liquid which the dyeing|staining processing part 132 has. In this embodiment, the conveyance path|route of the film which immerses the film ₂ in a process liquid is formed by the nip roll 112 and the guide rolls _{12 4-12} . In this configuration, the nip roll 112 and the guide roll 126 are before and after the dyeing treatment by the dyeing processing unit 132 is applied to the film ₂ (in other words, the dyeing processing unit _{13 2} ) _. before and after).

The processing liquid which the dyeing process part 132 in this embodiment has is the aqueous solution of a dichroic dye, and by a dyeing process, the film ₂ is dyed with a dichroic dye. The dyeing process by a normal dichroic dye is performed for the objective of making the film 2 adsorb|suck a dichroic dye. The treatment conditions are determined according to the desired optical properties within a range that can achieve this purpose and within a range where problems such as extreme dissolution and devitrification of the film 2 do not occur. Examples of the dichroic dye used for dyeing are iodine and dichroic dye.

When iodine is used as the dichroic dye, for example, at a temperature of 10 to 50°C, preferably 15 to 40°C, 0.003 to 0.2 parts by weight of iodine and 0.1 to 10 parts by weight of potassium iodide with respect to 100 parts by weight of water. A dyeing process is performed by immersing the film 2 in the aqueous solution containing part for 10-600 second, Preferably it is 30 to 300 second. Instead of potassium iodide, other iodides such as zinc iodide may be used. You may use another iodide together with potassium iodide. In addition, compounds other than iodide, such as boric acid, zinc chloride, cobalt chloride, etc., may coexist. If it is a treatment liquid containing 0.003 weight part or more of iodine with respect to 100 weight part of water, it can be regarded as a treatment liquid for dyeing.

When a water-soluble dichroic dye is used as the dichroic dye, for example, at a temperature of 20 to 80° C., preferably 30 to 60° C., in an aqueous solution containing 0.001 to 0.1 parts by weight of the dichroic dye with respect to 100 parts by weight of water. , for 10 to 600 seconds, preferably for 20 to 300 seconds, the dyeing treatment is performed by immersing the film 2 . The aqueous solution of the dichroic dye to be used may contain the dyeing aid etc., and may contain the inorganic salt like sodium sulfate, surfactant, etc. Only one type of dichroic dye may be used, and two or more types of dichroic dyes may be used together according to a desired color.

The crosslinking processing part 133 is a part which performs a bridge|crosslinking process on the film ₂ . _The crosslinking processing unit 133 has a processing tank in which the processing liquid for the crosslinking processing is stored. Crosslinking treatment is performed on the film ₂ by immersing the film in the treatment liquid of the crosslinking treatment section 133 . _In this embodiment, the conveyance path|route of the film which immerses the film ₂ in a process liquid is formed by the nip roll 113 and the guide rolls _127-129 . In this configuration, the nip roll 113 and the guide roll 129 are, before and after the crosslinking treatment by the crosslinking treatment unit ₁₃₃ is performed on the film 2 (in other words, the crosslinking treatment unit _{13 3} ) _. before and after).

The crosslinking treatment is a treatment performed for the purpose of water resistance by crosslinking or color adjustment (preventing the film 2 from appearing bluish, etc.).

_The treatment liquid used in the crosslinking treatment section 133 is, for example, an aqueous solution containing, for example, about 1 to 10 parts by weight of boric acid with respect to 100 parts by weight of water. When the dichroic dye used in the dyeing treatment is iodine, the treatment liquid used in the crosslinking treatment section 133 preferably contains iodide in addition to boric acid, and the amount is, for example, ₁ to 100 parts by weight of water. 30 parts by weight. Potassium iodide, zinc iodide, etc. are mentioned as an iodide. Compounds other than iodide, such as zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, and the like, may coexist.

_In the crosslinking treatment in the crosslinking treatment unit 133 , the concentrations of boric acid and iodide and the temperature of the treatment liquid can be appropriately changed according to the purpose.

For example, when the purpose of the crosslinking treatment is water resistance by crosslinking, and the polyvinyl alcohol-based resin film is subjected to swelling treatment, dyeing treatment, and crosslinking treatment in this order, the crosslinking agent-containing solution of the treatment solution has, for example, a concentration It is an aqueous solution of boric acid/iodide/water = 3 to 10/1 to 20/100 by weight. If necessary, other crosslinking agents such as glyoxal or glutaraldehyde may be used instead of boric acid, or boric acid and other crosslinking agents may be used in combination. The temperature of the processing liquid at the time of immersing the film 2 is about 50 degreeC - 70 degreeC normally, Preferably it is 53 degreeC - 65 degreeC, and the immersion time of the film 2 is about 10-600 seconds normally, Preferably it is 20 to 300 second, More preferably, it is 20 to 200 second. When the dyeing treatment and the crosslinking treatment are performed in this order on the film 2 stretched in advance before the swelling treatment, the temperature of the treatment liquid is usually about 50 to 85°C, preferably 55 to 80°C.

When the purpose of the crosslinking treatment is color adjustment, for example, when iodine is used as a dichroic dye, a crosslinking agent-containing solution having a concentration of boric acid/iodide/water = 1 to 5/3 to 30/100 in a weight ratio can be used as the treatment solution. . The temperature of the processing liquid at the time of immersing the film 2 is about 10-45 degreeC normally, and the immersion time of the film 2 is about 1-300 second normally, Preferably it is 2-100 second.

The washing process part 134 is a part which performs a washing process on the film ₂ after a crosslinking process. _The cleaning processing unit 134 has a processing tank in which a processing liquid for cleaning processing is stored. The washing process is performed on the film 2 by immersing the film ₂ in the process liquid which the washing|cleaning process part 134 has. In this embodiment, the conveyance path|route of the film which immerses the film 2 in a process liquid is formed by the nip roll 114 and the guide rolls _{12 10-12 12} . In this configuration, the nip roll 114 and the guide roll _{12 12 are} cleaned before and after the film ₂ is subjected to the cleaning treatment by the cleaning treatment unit 134 ( _in other words, the cleaning treatment unit 134 ). before and after). As a processing liquid in a washing process, the aqueous solution containing water, potassium iodide, and the aqueous solution containing boric acid are mentioned. The temperature of the processing liquid is usually about 2°C to 40°C, and the processing time is usually about 2 seconds to 120 seconds.

As for the washing process _in the washing|cleaning process part 134, you may wash|clean the film 2 by the method of spraying a process liquid as a shower, or the method of using immersion and spraying together.

The drying processing part 135 is a part which performs a drying processing on the film ₂ . In the present embodiment, the drying processing unit ₁₃₅ is a drying apparatus. The film ₂ washed by the washing processing unit 134 is loaded into the drying processing unit 135 , and the film ₂ is dried while the film ₂ passes through the drying processing unit 135 . . In this embodiment, the conveyance path|route of the film which immerses the film ₂ in a process liquid is formed by the nip rolls ₁₁₅ and 116 . In order to support and convey the film ₂ in the drying process part 135, the guide roll 12 may be arrange|positioned suitably. Drying by the drying processing unit 135 is performed for about ₃₀ seconds to about 600 seconds _in the drying processing unit 135 maintained at a temperature of about 40°C to 100°C. _In FIG. 1, the drying process part 135 is shown typically. The dry processing part 135 will not be specifically limited if the water|moisture content adhering to the film ₂ can be dried, Manufacture of a polarizing film WHEREIN: A well-known thing used normally may be sufficient as it.

In the manufacturing apparatus 10, the circumferential speed difference of the at least two nip rolls 11 (the upstream nip roll 11 and the downstream nip roll 11) in the some nip roll 11 is used A stretching treatment of uniaxially stretching the film 2 is performed. In this case, the two nip rolls 11 contributing to the said uniaxial stretching process function as an extending|stretching part.

For example, you may perform the extending|stretching process of carrying out a uniaxial stretching process using the peripheral speed difference of the nip roll 113 arrange|positioned before the bridge|crosslinking processing part ₁₃₃ , _and the nip roll 114 arrange|positioned _{behind the} bridge|crosslinking processing part 133. In this case, since an extending|stretching process is performed in parallel with a crosslinking process, the bridge|crosslinking process part ₁₃₃ also functions as an extending|stretching process part. The stretching treatment is also effective in suppressing the occurrence of wrinkles.

The stretching treatment is mainly performed using two nip rolls ₁₁ disposed before and after one treatment section (eg, the crosslinking treatment section 133 described above), while the stretching treatment is gradually performed using the other nip roll 11. You may do more.

The manufacturing apparatus 10 may have an extending|stretching process part for performing an extending|stretching process separately. _In this case, the extending|stretching process part is arrange|positioned, for example at the rear end of the crosslinking process part 133 (for example, between the crosslinking process part ₁₃₃ and the washing|cleaning process part ₁₃₄ ).

The manufacturing apparatus 10 may have a plurality of processing units of at least one of the swelling processing unit _{13 1} , the dyeing processing unit 13 ₂ , the crosslinking processing unit 13 ₃ , the washing processing unit ₁₃₄ , and the drying processing unit 135 . good. For example, the manufacturing apparatus 10 may be provided with two or more bridge|crosslinking process parts 133 ₃ . It is the same when the manufacturing apparatus 10 is equipped with an extending|stretching process part, and the manufacturing apparatus 10 may be provided with two or more extending|stretching parts, for example.

When manufacturing the polarizing film 4 using the said manufacturing apparatus 10, first, the film 2 is unwound from the original roll 6, and it is made into the some nip roll 11 and the some guide roll 12. The film 2 is conveyed in the longitudinal direction along the conveyance path|route formed. 1 m/min - 60 m/min may be sufficient as the example of a conveyance speed, and they are 1.5 m/min - 50 m/min. In the conveyance route of the film 2, from the raw roll 6 side, the swelling processing unit 13 ₁ , the dyeing processing unit 13 ₂ , the crosslinking processing unit 13 ₃ , the washing processing unit ₁₃₄ , and the drying processing unit ₁₃₅ . ) is installed. Moreover, as mentioned above, the at least two nip rolls 11 also have a function as an extending|stretching part. Therefore, while a swelling process, a dyeing process, a crosslinking process, a washing process, and a drying process are given to the film 2 being conveyed, an extending|stretching process is performed. Thereby, linearly polarized light characteristic (optical characteristic) is provided to the film 2, and the polarizing film 4 is obtained.

The polarizing film ₄ obtained through the drying process part 135 is used for manufacture of the polarizing plate containing the polarizing film 4, for example. For example, the polarizing plate may be manufactured by performing a bonding process of bonding a protective film to one or both surfaces of the polarizing film 4 . The polarizing film ₄ obtained through the drying processing part 135 may be conveyed continuously for manufacture of the said polarizing plate, and may be wound up once in roll shape.

As shown in FIG. 2, in the process of carrying out N processes, conveying the film 2, and manufacturing the polarizing film 4 WHEREIN: The length of the width direction of the film 2 changes. Let the width of the film 2 in the location (henceforth an "upstream location") located on the upstream among arbitrary two locations in conveyance of the film 2 W1, rather than an upstream location Let the width of the film 2 at a location located on the side (hereinafter referred to as "downstream location") be W2, and the rate of change of the width of the film 2 between the upstream location and the downstream location is the neck-in rate When referred to as (%), in this embodiment, a neck-in rate is defined by the following formula|equation.

Neck-in ratio = ((W1-W2)/W1)×100

In one Embodiment of this invention, it further has the monitoring process of monitoring the said neck-in rate. In a monitoring process, as shown in FIG. 1, the width|variety of the film 2 is continuously measured at the some measurement point 20 (plural places) in the film 2 being conveyed. In FIG. 1 , a plurality of measurement points 20 of the width of the film 2 are indicated by arrows. In the case where the plurality of measurement points 20 are distinguished and described, the plurality of measurement points 20 are called measurement points 20 ₁ to 20 ₁₂ .

The measuring point 20 may be a point for measuring the width of the film 2 wound around the nip roll 11 or the guide roll 12 , or may be a point that is not wound on the nip roll 11 or the guide roll 12 . The point for measuring the width of the film 2 may be sufficient. The measuring point 20 shown in FIG. 1 is an example, for example, the measuring point 20 ₁ may be in the position which measures the width|variety of the film 2 sent out from the nip roll 11 ₁ , The measuring point 20 ₄ ) may exist in the position which measures the width|variety of the film ₂ (film ₂ on the guide roll 126) wound around the guide roll 126.

It is preferable that the measurement points 20 ₁ to 203 before the dyeing treatment is performed on the film ₂ are points for measuring the width of the film 2 wound around the nip roll 11 or the guide roll 12 . . _On the other hand, after the measurement point 204 , the relationship between the nip roll 11 or the guide roll 12 and the film 2 is not normally limited.

The measuring point 20 can be arranged, for example, before or after one of the N treatments is applied to the film 2 . For example, the measurement point 201 is a point for measuring the width of the film 2 immediately after being sent out from the state or nip roll 11 _{1 wound around the nip roll 11 1 in} FIG. ₁ , and swelling treatment This is the measurement point before . The measurement point ₂₀₂ is a point for measuring the width of the film _{2 on} the guide roll 123 or immediately after being sent out from the guide roll 123 .

Accordingly, the measurement points 20 ₁ , 20 ₂ are measurement points of the width of the film 2 before and after the swelling treatment is applied to the film 2 . In this way, the measurement points before and after a process is performed (before and after the film is immersed in the processing liquid of a certain processing part) are also measurement points before and after the processing part where the processing is performed.

Other examples of such measurement points 20 are measurement points 20 ₃ , 20 ₄ , measurement points 20 ₅ , 20 ₇ , measurement points 20 ₈ , 20 ₁₀ , and measurement points 20 ₁₁ , 20 ₁₂ . )to be. The measurement points 20 ₃ , 20 ₄ , the measurement points _{205 , 20 7 ,} and the measurement points 20 ₈ , 20 ₁₀ are films before and after the swelling treatment, the dyeing treatment, the crosslinking treatment and the washing treatment are performed. (2) is the measurement point of the width. The measurement points 20 ₁₁ , 20 ₁₂ are measurement points of the width of the film 2 before and after the drying treatment is performed.

The measurement point 20 may be a point at which the width of the film 2 is measured during a process in which one treatment is being performed on the film 2 . An example of such a measurement point ₂₀ is the measurement point ₂₀₆ , 209 . The measurement point 206 is a measurement point in the middle of which the film ₂ is being conveyed between the guide roll ₁₂₇ and the guide roll ₁₂₈ . Similarly, the measurement point _{209 is a measurement point in the middle of the film 2 being conveyed between the guide roll 12 10 and} the guide roll 12 ₁₁ . At the measurement points ₂₀₆ , 209 , the width of the film ₂ in the treatment liquid is measured.

In a monitoring process, the same timing in the said two places among the measurement results which measured the width|variety of the film 2 in each of two places (upstream location and downstream location) previously selected from the some measurement point 20 in advance. Calculate the neck-in rate based on the measurement results measured at (ie, simultaneously). The above "same timing (that is, at the same time)" may be slightly shifted without departing from the spirit of the present invention. The time difference between the measurement at the upstream location and the downstream location is not particularly limited, but may be about 1 minute or less, may be within 30 seconds, may be within 20 seconds, or may be within 10 seconds. It is preferable to automate (automated) and implement a monitoring process.

In the example of the upstream location and the downstream location, the upstream location is before one of the N treatments (hereinafter referred to as "predetermined treatment"), and the downstream location is after the predetermined treatment. For example, when the predetermined treatment is a dyeing treatment, the upstream portion is before the dyeing treatment, and the downstream portion is after the dyeing treatment. "Before predetermined processing" and "after predetermined processing" include cases in which other processing is performed between an upstream location and a downstream location and the "predetermined processing".

If any two adjacent processes among the N processes are referred to as i-1 th processing and i th processing (i is an integer greater than or equal to 2), and corresponding processing units are referred to as i-1 th processing units and i-th processing units, the upstream Any one of the following arrangement examples 1-3 may be sufficient as a location and a downstream location.

[Arrangement Example 1]

The upstream point is at a position during the i-1 processing (position of the i-1 processing unit), and the downstream location is the position of the i-1 processing (i-1 processing unit) and the position of the i-th processing (i-th processing unit) be in between For example, when the i-1th process is a crosslinking process, in the plurality of measurement points _{20 shown} in FIG. 1 , examples of the upstream location and the downstream location are the measurement point 206 and the measurement point 207 . to be.

[Arrangement Example 2]

The upstream location and the downstream location are between the position of the i-1 th processing (i-1 processing unit) and the position of the i th processing (i-th processing unit), respectively. For example, when the i-1th process is a crosslinking process, in the plurality of measurement points 20 _shown in FIG. 1 , examples of the upstream location and the downstream location are the measurement point 207 and the measurement point ₂₀₈ . to be.

[Arrangement Example 3]

The upstream location is at a position before the i-1 processing (i-1 processing unit), and the downstream location is at a position during the i-1 processing (position of the i-1 processing unit). For example, when the i-1th process is a crosslinking process, in the plurality of measurement points 20 _shown in FIG. ₁ , examples of the upstream location and the downstream location are the measurement point 205 and the measurement point 206 . to be.

When i is an integer of 2 or more, the processing following the i-th processing is called the i+1-th processing, and the corresponding processing unit is called the i+1-th processing unit, examples of the upstream location and the downstream location are the following arrangement example 4 it's good too

[Arrangement Example 4]

The upstream location is between the position of the i-1 th processing (i-1 processing unit) and the position of the i th processing (i-th processing unit), and the downstream location is between the position of the i-th processing (i-th processing unit) and the i+ It is between the positions of the 1st process (i+1th processing unit). For example, when the i-1 process is a crosslinking process, in the plurality of measurement points 20 shown in FIG. 1 , examples of the upstream location and the downstream location are the measurement point _{207 and the measurement point 20 10 .} to be.

As a set of the upstream point and the downstream location, for example, the upstream location is the measurement point 20 ₁ and the downstream location is the measurement point 208 . Even if a set of two measurement points ₂₀ that are not adjacent to each other is adopted good.

When the manufacturing apparatus 10 has a plurality of at least one of the swelling processing unit _{13 1} , the dyeing processing unit 13 ₂ , the crosslinking processing unit 13 ₃ , the washing processing unit ₁₃₄ , and the drying processing unit 135 , upstream The location and the downstream location may be a location where processing for the same purpose is performed, respectively, or a location where processing for a different purpose is performed. For example, when the manufacturing apparatus 10 has two or more swelling processing parts 13 ₁ and the two swelling processing parts 13 ₁ are called swelling processing parts 13 ₁ -a, 13 _1- b, an upstream location It may be in the position (or before or after) of the swelling processing part 13 ₁ -a, the downstream location may be in the position (or before or after that) of the swelling processing part 13 ₁ -b, and the upstream part may be the swelling processing part ( 13 ₁ -a) or the position (or before or after) of the swelling processing part 13 _{1 -} b, and a downstream location may exist in the position (or before or after that) of the dyeing|staining processing part 132. The same applies to the case where there are two or more stretching processing units.

The neck-in rate may be calculated from a plurality of sets of an upstream location and a downstream location selected from the plurality of measurement points 20 . For example, the neck-in rate is calculated based on the measurement result at the measurement point _{20 1} and the measurement result at the measurement point 202 , and the measurement result at the measurement point ₂₀₅ and the measurement point 20 You may calculate a neck-in rate based on the measurement result in ₇ ). In the plurality of sets of the upstream location and the downstream location, there may be a set in which the upstream location or the downstream location is common. For example, the neck-in rate is calculated based on the measurement result of the measurement point 201 and the measurement result _of the measurement point ₂₀₂ , and the measurement result _of the measurement point 201 and the measurement point ₂₀₄ are measured. You may calculate a neck-in rate based on a result. Similarly, the neck-in rate is calculated based _on the measurement result of the measurement point ₂₀₅ and the measurement result of the measurement point 207 , and the measurement result of the measurement point ₂₀₆ and the measurement of the measurement point ₂₀₇ . You may calculate a neck-in rate based on a result.

In order to calculate the neck-in ratio, the optical film manufacturing apparatus 10 has a plurality of width measuring devices 30 and a calculation unit 40 as shown in FIG. 3 .

Each width measuring device 30 is a device for continuously measuring the width of the film 2 . The plurality of width measuring devices 30 are arranged one-to-one at the plurality of measurement points 20 . That is, one width measuring device 30 is disposed at one measuring point 20 . In FIG. 3 , among the plurality of width measuring devices 30 , two width measuring devices 30 selected for calculating the neck-in ratio (that is, an upstream width measuring device 30 _UP disposed at an upstream location, and disposed at a downstream location) The downstream width measuring device 30 _DOWN ) and the calculation unit 40 are schematically shown.

The width measuring device 30 has two end detectors 31 . One of the two end detectors 31 is a detector that detects one end 2a in the width direction of the film 2, and the other end 2b is the other end 2b in the width direction of the film. ) (the end opposite to the end 2a). The width measuring device 30 is configured to detect the end portions 2a and 2b of the film 2 according to the state of the film 2 at the measurement point 20 . Therefore, the structure of the width measuring device 30 may differ for every measurement point 20. As shown in FIG. However, the configuration of the two end detectors 31 (two end detectors 31 arranged at one measuring point 20) of one width measuring device 30 is the same.

4 : is a schematic diagram for demonstrating the schematic structure of the edge part detector 31A which is an example of the edge part detector 31. As shown in FIG. 31 A of edge part detectors are detectors applied when measuring the width|variety of the film 2 on the conveyance roll R. The conveyance roll R is the nip roll 11 or the guide roll 12 shown in FIG.

Two end detectors 31A are arranged for the film 2 to detect the ends 2a and 2b, respectively. Since the configuration of the end detector 31A is the same as described above, a case in which the end detector 31A detects the end portion 2a will be described.

The end detector 31A includes a light irradiation unit 32 and a light detection unit 33 . In FIG. 4, the case where the film 2 is arrange|positioned on the conveyance roll R is illustrated.

The light irradiation part 32 irradiates light toward the film 2 . The light irradiation part 32 is comprised so that light may be irradiated to the outer side from the edge part 2a and the edge part 2a of the film 2. Therefore, as shown in FIG. 4 , when the film 2 is disposed on the conveyance roll R, the light from the light irradiation unit 32 does not overlap the film 2 among the conveyance rolls R. Areas that are not covered are also investigated. The light irradiation unit 32 may be a line-type light source extending in the width direction of the film 2 . The light irradiation unit 32 may include, for example, an LED.

The light irradiation unit 32 may be disposed in the case 34 . The case 34 has a window portion 34a in order to irradiate the film 2 with the light output from the light irradiation unit 32 . The window portion 34a may be formed of a material that transmits the light output from the light irradiation portion 32 . For example, examples of the material of the window portion 34a include polycarbonate resin, acrylic resin, vinyl chloride resin, polypropylene resin, polyethylene terephthalate resin, and glass.

The light detection unit 33 detects the luminance of the light (reflected light) reflected by the light irradiated onto the film 2 from the light irradiation unit 32 by the film 2 . The light detection unit 33 may be an imaging unit such as a camera (eg, a CCD camera) that images at least the end 2a of the film 2 . As shown in FIG. 4 , when the film 2 is disposed on the conveyance roll R, the light detection unit 33 is, for example, conveyed from the light irradiated to the film 2 from the light irradiation unit 32 . The luminance of the light reflected from the roll R is also detected.

The light detection unit 33 may be disposed in the case 35 . The case 35 has a window portion 35a for detecting the reflected light by the light detection unit 33 . The window portion 35a may be made of a material that transmits the reflected light. Examples of the material of the window portion 35a are the same as in the case of the window portion 34a.

The measurement points 20 ₁ , 20 ₂ , 20 ₃ before the dyeing treatment is applied to the film 2 are usually points for measuring the width of the film 2 on the conveyance roll R . Thus, the end detector 31A is suitably applied at the measuring points 20 ₁ , 20 ₂ , 20 ₃ .

5 : is a schematic diagram for demonstrating the schematic structure of the edge part detector 31B which is another example of the edge part detector (width measuring device) 31. As shown in FIG. The end detector 31B is a detector applied to the film 2 when linearly polarized light characteristic is generated (when an absorption axis is formed). Usually, the edge part detector 31B can be applied with respect to the film 2 after the dyeing process in the dyeing process part 13 ₂ is performed.

Two end detectors 31B are arranged for the film 2 to detect the ends 2a and 2b, respectively. However, since the configuration of the end detector 31B is the same as described above, a case in which the end detector 31B detects the end portion 2a will be described.

The end detector 31B has a photodetector 36 and a polarization filter 37 .

The light detection unit 36 includes light from the surrounding environment of the film 2 incident on the film 2 and light transmitted through the film 2 (hereinafter referred to as “light from the film 2 ”). detect the luminance of The light detection unit 36 may be an imaging unit such as a camera (eg, a CCD camera) that images at least the end 2a of the film 2 .

The said "light of the surrounding environment of the film 2" is the illumination light from the lighting fixture installed in the factory which manufactures the polarizing film 4, and the element which the said illumination light comprises the manufacturing apparatus 10 (for example, the nip roll 11 ) and a conveying roll R such as the guide roll 12, at least one of the side wall and the bottom wall of the treatment tank of each processing unit shown in FIG. 1, and the light reflected by the factory floor, etc.). In FIG. 5 , the light of the surrounding environment of the film 2 is schematically indicated by a white arrow.

The polarizing filter 37 is a filter having linear polarization characteristics. The polarizing filter 37 is disposed between the light detection unit 36 and the film 2 so that the absorption axis of the film 2 and the absorption axis of the polarizing filter 37 are in a cross nicol state. The cross nicol state is not limited to the case where the angle between the absorption axis of the film 2 and the absorption axis of the polarizing filter 37 is 90°, for example, ±5°, ±10° or 15° with respect to 90°. It is meant to include some degree of error.

The light detection unit 36 and the polarization filter 37 may be disposed in the case 35 having the window portion 35a as in the case of the light detection unit 33 . The window part 35a should just be a material which can transmit the light from the film 2 .

In the case of using only light from the surrounding environment of the film 2, when the difference in luminance between the light from the surrounding environment detected by the light detection unit 36 and the light transmitted through the film 2 is small, the end detector 31B is You may have an auxiliary lighting part (light irradiation part). The configuration of the auxiliary lighting unit may be the same as that of the light irradiation unit 32 . The auxiliary lighting unit may be configured to output light that is smaller than the light irradiation unit 32 or has a power smaller than the power of the light output from the light irradiation unit 32 . The auxiliary lighting unit may be disposed in the case 34 having the window 34a as in the case of the light irradiation unit 32 . The auxiliary lighting unit illuminates the detection area (or imaging area) of the light detection unit 36 and at least one of its periphery, and is arranged so that light from the auxiliary illumination unit is incident on the film 2 as light of the surrounding environment.

You may use the edge part detector 31B, when measuring the width|variety of the film 2 on the conveyance roll R. The end detector 31B can be used, for example, for measurements at measuring points _{205 , 20 8 ,} 20 ₁₀ . In this case, the conveyance roll R is preferably a white roll in order to clarify the difference in luminance.

You may use the edge part detector 31B, when measuring the width|variety of the film 2 between the conveyance roll R and the conveyance roll R. The end detector 31B can be used, for example, to measure the width of the film 2 at the measuring points 20 ₄ , 20 ₆ , 20 ₇ , 20 ₉ , 20 ₁₁ , 20 ₁₂ . In this case, in order to clarify the difference in luminance, a white plate-shaped member or the like may be provided in the background of the detection area of the photodetector 33 (or the background of the imaging area). In the measurement of the width of the film 2 between the two conveying rolls R, when an auxiliary lighting unit is used, the auxiliary lighting unit may be arranged on the same side as the end detector 31B with respect to the film 2, It may be arranged on the side opposite to the end detector 31B with respect to the film 2 .

In the case of measurement of the width of the film ₂ at the measurement points 206 , 209 , the end detector 31B measures the width of the film ₂ in the treatment liquid. In this case, for example, the end detector 31B has a case 35 having a window portion 35a, as shown in FIG. 5, and the case 35 is arranged such that a portion of the window portion 35a is located in the treatment liquid. may be When the portion of the window portion 35a is disposed in the processing liquid, the outer surface of the window portion 35a may be subjected to at least one of hydrophilic treatment, concavo-convex processing, and bevel processing. This makes it easy to accurately detect the edge portion 2a of the film 2 because, for example, bubbles do not easily stay on the outer surface of the window portion 35a. In the measurement of the width of the film 2 in the treatment liquid, when an auxiliary lighting unit is used, for example, the auxiliary lighting unit may illuminate the bottom wall of the treatment tank in which the treatment on the film 2 is performed. In this case, the luminance of the transmitted light irradiated from the auxiliary lighting unit, reflected by the bottom wall of the treatment tank, and transmitted through the film 2 is detected by the light detection unit 36 through the polarizing filter 37 .

The polarizing filter 37 included in the end detector 31B may be disposed on the incident side of light to the film 2 , for example. For example, when the end detector 31B has an auxiliary illumination unit (light irradiation unit), the polarizing filter 37 is disposed between the auxiliary illumination unit and the film 2 , not the light detection unit 33 , the polarizing filter 37 . may be placed. Also in this case, the polarizing filter 37 is arrange|positioned in the film 2 and a cross nicol state.

The calculation unit 40 shown in Figs. 3 to 5 is wired or wirelessly connected to a plurality of width measuring devices 30 (width measuring devices 30 disposed at an upstream location and a downstream location), and a plurality of width measuring devices Based on the measurement result acquired from (30), the said neck-in rate is computed.

Specifically, the calculation part 40 is the edge part 2a and the edge part 2b of the film 2 in the arrangement location of each width measurement device 30 based on the measurement result of the some width measurement device 30. to judge The ends 2a and 2b can be judged by changes in the luminance data that are the measurement results of the width meter 30 .

For example, as shown in FIG. 4 , by a width measuring device 30 including an end detector 31A, the width of the film 2 in which the film 2 is disposed on the conveying roll R is measured. In this case, the light detection part 33 detects the brightness|luminance of the reflected light from the film 2, and the reflected light from the conveyance roll R. Since a difference arises between the brightness|luminance of the reflected light from the film 2, and the brightness|luminance of the reflected light from the conveyance roll R, the calculating part 40 calculates the location where the difference has arisen, the edge part 2a, 2b of the film 2 ) can be determined.

For example, as shown in FIG. 5 , when the width of the film 2 is measured by the width measuring device 30 including the end detector 31B, the polarizing filter 37 and the film 2 are cross nicol. state, light from the film 2 is substantially blocked, while light from other than the film 2 is detected. Therefore, in the image formed from the luminance data detected by the light detection unit 36, a difference in luminance occurs at locations other than the film 2 and the film 2 (the film 2 side is dark, and the film 2 is other than the film 2). is bright), the calculation unit 40 may determine the location where the difference is occurring as the edge portions 2a and 2b of the film 2 .

When the end portions 2a, 2b of the film 2 are specified, the calculation unit 40, for example, the arrangement position of the end detector 31A (or the end detector 31B), and the end portion ( The width of the film 2 is calculated from the relationship with the positions of 2a and 2b). When, for example, the edge part of the conveyance roll R can be specified from the luminance data obtained by the edge detector 31A (or the edge detector 31B), the edge part of the conveyance roll R in the luminance data and the film 2 ), the width of the film 2 is computed from the relationship with the position of the edge parts 2a, 2b, and the position of the edge part of the actual conveyance roll R.

Next, the calculation unit 40 includes two width measuring devices 30 (upstream side width measuring device 30 _UP ) and a downstream side each arranged at an upstream point and a downstream location selected in advance among the plurality of measurement points 20 . A neck-in ratio is computed using the width of the film 2 calculated based on the measurement result of the width measuring instrument _30DOWN ). Examples of the upstream location and the downstream location are as described above.

In the manufacturing method of the said polarizing film 4, and the manufacturing apparatus 10 of the polarizing film 4, the width|variety of the film 2 is the width measuring instrument 30 arrange|positioned at each of the some measurement point 20 (plural places). ) to be measured. Thereby, conveying the film 2, the width|variety of the film 2 can be measured continuously. Moreover, based on the measurement result of the width of the film 2 measured at the same timing in an upstream location and a downstream location among the width|variety of the film 2 continuously measured at the some measurement point 20, a neck-in rate to calculate Therefore, during conveyance of the film 2, the neck-in rate of the film 2 is obtained in real time. That is, the neck-in rate can be efficiently measured. In other words, it is possible to monitor the neck-in rate in real time.

The neck-in rate represents the rate of change of the width of the film 2 . Therefore, for example, in the location where the width measurement is performed, if the permissible range of the neck-in ratio obtained through preliminary experiments or simulations (control width of the neck-in ratio) is exceeded, for example, the film 2 may break in a post-process, or the film ( The thickness of 2) deviate|deviates from the desired thickness (thickness by design), or the film as a defect which is inferior in external appearance, such as desired optical characteristics, stripes, and unevenness, may be manufactured.

Therefore, in the manufacturing method of the said polarizing film (optical film) 4 which can monitor a neck-in rate in real time, and the manufacturing apparatus 10 of the polarizing film 4, when a neck-in rate exceeds a permissible range In, for example, the production of the polarizing film 4 can be stopped. When manufacturing is interrupted, what is necessary is just to adjust the manufacturing conditions of the polarizing film 4 (for example, adjustment of a processing liquid, adjustment of extending|stretching process conditions, etc.) so that a neck-in rate may become a permissible range. Also, for example, manufacturing may be continued while adjusting the neck-in ratio to be within an acceptable range. Thereby, the fracture|rupture of the film 2 in the post-process mentioned above can be prevented, or manufacture of the polarizing film 4 used as the said defect can be suppressed. Therefore, the polarizing film 4 can be manufactured by a stable process. Moreover, the polarizing film 4 with stable quality can be manufactured uniformly. Moreover, the material cost of the polarizing film 4 can be reduced. Moreover, since the polarizing film (optical film) 4 of good quality can be manufactured efficiently, the manufacturing yield of the polarizing film 4 improves.

The width of the film 2 is easy to change when the film 2 is subjected to at least one of N treatments. Therefore, as mentioned above, when an upstream location is before a predetermined process among N processes, and a downstream location is after a predetermined process, the problem in manufacture of the polarizing film 4 (for example, the film 2 in a post-process) fracture of the film 2, deviation from the desired thickness, etc.) is easy to monitor.

For the same reason, it is easy to monitor the neck-in rate contributing to the malfunction in manufacture of the polarizing film 4 also in the case of arrangement examples 1-4 mentioned above. For example, in the batch state, it is possible to specify that a change in state before or after a certain process, a change in state resulting from the process, or a change in state in the middle of the process affects the neck-in rate. Therefore, when the neck-in rate is out of an allowable range, it is easy to adjust manufacturing conditions.

As a result, while being able to further reduce the material cost of the polarizing film 4, the manufacturing yield of the polarizing film 4 can be improved further. Moreover, by a more stable process, quality can manufacture the still more stable polarizing film 4 uniformly.

In the case of measuring the width of the film 2 at the measurement point 20 ₁ (before N treatments are performed), the film 2, for example, has no linearly polarized light characteristic. Therefore, the film 2 is a transparent film which does not have an absorption axis normally. In this case, by detecting the ends 2a and 2b of the film 2 on the conveyance roll R using the width measuring instrument 30 having the end detector 31A shown in FIG. 4 , the The ends 2a and 2b can be reliably detected. As a result, the width of the film 2 can be measured more accurately. Here, the case of the measurement point 20 ₁ has been described by way of example, but the measurement point 20 ₂ , 20 ₃ is also similarly, using the width measurement device 30 having the end detector 31A shown in FIG. 4 , the film The ends 2a and 2b of (2) can be reliably detected.

When the film 2 is subjected to a dyeing treatment and a stretching treatment, linearly polarized light properties are imparted to the film 2 . When the film 2 is conveyed, tension is applied to the film 2 along the conveyance direction of the film 2 . Therefore, while conveying the film 2, when an extending|stretching process is gradually performed in any one of a swelling process, a dyeing process, a crosslinking process, and a drying process, linearly polarization|polarized-light characteristic is gradually provided to the film 2 after a dyeing process. In addition, as shown in FIG. 1, a drying process is normally implemented at the end of N processes. Therefore, in the case of measuring the width of the film 2 after the dyeing treatment and the stretching treatment have been performed, by using the width measuring device 30 having the end detector 31B shown in Fig. 5 , the film 2 is width can be reliably detected. As a result, the width of the film 2 can be measured more accurately.

As shown in FIGS. 4 and 5 , in the form in which the width measuring device 30 includes the cases 34 and 35 , the light irradiating unit 32 and the light detecting units 33 and 36 can be prevented from corrosion by iodine. can Since the processing liquid containing iodine is used for manufacture of the polarizing film 4, iodine exists in a manufacturing environment, and corrodes the light detection parts 33, 36 etc., for example. In contrast, as shown in FIGS. 4 and 5 , by arranging the light irradiation unit 32 and the light detection units 33 and 36 in the cases 34 and 35 , corrosion by the iodine can be prevented. It is preferable to make the inside of the cases 34 and 35 positive pressure by supplying air or the like.

In conjunction with the embodiment described above, various modifications have been described. However, this invention is not limited to the said embodiment and various modified examples, It is shown by a claim, and it is intended that the meaning of a claim and equivalent and all the changes within the range are included.

The case of manufacturing a polarizing film as an optical film was illustrated. However, the present invention can be applied to a method and apparatus for manufacturing an optical film requiring monitoring of the neck-in rate in the process of manufacturing an optical film from the film. Other examples of the optical film include a protective film, a retardation film, a surface treatment film, an antireflection film, and a diffusion film.

The width measuring device having the end detector 31B shown in Fig. 5 is a point for measuring the width of the film subjected to the dyeing treatment and the stretching treatment, the upstream portion when the N treatments include the dyeing treatment and the stretching treatment It can be applied appropriately in the case of In this case, when measuring the width|variety of a film in an upstream location, it is because there exists a tendency for the linearly-polarized-light characteristic to generate|occur|produce in a film. When performing N processings conveying a film, an extending|stretching process is gradually given to a film as mentioned above. Therefore, even if an upstream location is a location which measures the width of the film to which the dyeing process was given, the width measuring device which has the edge part detector 31B is applicable suitably.

The measuring method of the width|variety of the film 2 is not specifically limited to the illustrated method. For example, you may measure a width|variety with measuring instruments, such as a laser type displacement meter and an LED type displacement meter. You may image|photograph the whole film 2 with a camera etc., and may compute the width|variety from the image obtained. As shown in FIG. 3 , in the method of acquiring the positions of the ends 2a and 2b of the film 2 , the positions of the ends 2a and 2b are measured at each of the ends 2a and 2b of the film 2 . Since what is necessary is just to arrange|position the apparatus to do, it is preferable from a viewpoint of installation space and apparatus management (maintenance inspection, etc.).

The extending|stretching process in an extending|stretching part is not limited to the wet extending|stretching method, A dry extending|stretching method may be employ|adopted. In the above-mentioned embodiment, the order of the process illustrated in order to manufacture a polarizing film may be suitably changed or combined in the range which does not deviate from the meaning of this invention. One may be sufficient as the number of the processing tank which each processing part has, and multiple may be sufficient as it. The N processes are not limited to the number of exemplified processes.

The definition of the change rate (neck-in rate) of the width of a film will not be limited to the definition illustrated as long as the rate of change of the width of a film between an upstream location and a downstream location is shown.

The above-described embodiment and various modifications may be appropriately combined within a range not departing from the spirit of the present invention.

2: film
4: Polarizing film (optical film)
10: manufacturing device
11: nip roll (conveying mechanism)
12: guide roll (conveying mechanism)
20: measurement point (plural points)
30: width gauge
30 _UP : Upstream side width measuring device
30 _DOWN : downstream width measuring instrument
32: light irradiation unit
33: light detection unit (imaging unit)
36: light detection unit (imaging unit)

Claims (22)

A method of manufacturing an optical film by subjecting a long film to N treatments (N is an integer greater than or equal to 1),
The N treatments are performed while conveying the film,
During the conveyance, the width of the film is continuously measured at each of the plurality of locations, and the measurement result obtained at the same timing among the measurement result at the upstream location and the measurement result at the downstream location among two locations selected from the plurality of locations Based on, the manufacturing method of the optical film which computes the change rate of the width|variety of the said film. The method according to claim 1, wherein the upstream location is at a position before one of the N treatments is performed,
The manufacturing method of the optical film whose said downstream location exists in the position after said one process was performed. The method according to claim 1 or 2, wherein the N processes include i-1 th processing, i th processing, and i+1 th processing (i is an integer of 2 or more),
the upstream location is between the position of the i-1th treatment and the position of the i-th treatment, and the downstream location is between the position of the i-th treatment and the position of the i+1th treatment. manufacturing method. The method according to claim 1 or 2, wherein the N processes include i-1 th processing and i th processing (i is an integer greater than or equal to 2),
the upstream location is at a position during the i-1 processing and the downstream location is between the location of the i-1 processing and the position of the i-th processing;
the upstream location and the downstream location are respectively between the position of the i-1 th treatment and the position of the i th treatment, or
The manufacturing method of the optical film whose said upstream location exists in the position before the said i-1 process, and the said downstream location exists in the position during the said i-1 process. The manufacturing method of the optical film in any one of Claims 1-4 which measures the said width|variety in the said film by acquiring the image of the at least edge part of a film with an imaging part during the said conveyance. . The width in the film according to any one of claims 1 to 4, wherein the width in the film is determined based on the luminance of at least one of the reflected light and transmitted light from the film by the light incident on the film during the conveyance. The manufacturing method of the optical film to measure. The film according to any one of claims 1 to 6, wherein the film is conveyed by a conveying roll,
By irradiating the light to the film on the conveyance roll, and detecting an edge portion of the film based on the difference in luminance of the reflected light of the film and the conveying roll generated by the irradiation of the light, the above in the film A method of manufacturing an optical film, wherein the width is measured. The method of claim 6 , wherein the transmitted light is transmitted light from the film by light incident on the film through a polarizing filter. The manufacturing method of the optical film of Claim 6 which measures the width|variety in the said film based on the brightness|luminance of the light obtained by making the said transmitted light pass through a polarizing film. The method for producing an optical film according to any one of claims 1 to 9, wherein the N treatments include at least one treatment of swelling treatment, dyeing treatment, crosslinking treatment, stretching treatment, and drying treatment. The method for manufacturing an optical film according to any one of claims 1 to 10, wherein the optical film is a polarizing film. N processing units (N is an integer greater than or equal to 1) for performing a process for imparting at least optical properties to the film;
a conveying mechanism for conveying the film;
a plurality of width measuring devices disposed at a plurality of locations on the conveying mechanism and continuously measuring the width of the film being conveyed by the conveying mechanism at each of the plurality of locations;
Calculation for calculating the rate of change of the width of the film based on the measurement result obtained at the same timing among the measurement result of the upstream width measurement device and the measurement result of the downstream width measurement device among the two width measurement devices selected from the plurality of width measurement devices wealth
A manufacturing apparatus for an optical film comprising a. 13. The method of claim 12, wherein the upstream width measurer is disposed in front of one of the N processing units;
and the downstream width measuring device is disposed behind the one processing unit. The method according to claim 12 or 13, wherein the N processing units include an i-1th processing unit, an i-th processing unit, and an i+1th processing unit (i is an integer greater than or equal to 2),
The upstream width measuring device is disposed between the i-1th processing unit and the i-th processing unit,
The downstream width measuring device is an optical film manufacturing apparatus disposed between the i-th processing unit and the i+1-th processing unit. The method according to claim 12 or 13, wherein the N processing units include an i-1 th processing unit and an i th processing unit (i is an integer of 2 or more),
the upstream-side width measuring device is disposed at the position of the i-1th processing unit, and the downstream-side width measuring device is disposed between the i-1 th processing unit and the i-th processing unit;
the upstream side width measuring device and the downstream side width measuring device are respectively disposed between the i-1 th processing unit and the i th processing unit, or
The apparatus for producing an optical film, wherein the upstream width measuring device is disposed in front of the i-1 processing unit, and the downstream side width measuring device is disposed at the position of the i-1 processing unit. The apparatus for manufacturing an optical film according to any one of claims 12 to 15, wherein at least one of the plurality of width measuring devices has an imaging unit that images at least an end portion of the film. 16. The method according to any one of claims 12 to 15, wherein at least one of the plurality of width measuring devices has a light detection unit for detecting at least one of reflected light and transmitted light from the film by light incident on the film An apparatus for manufacturing an optical film. The apparatus for manufacturing an optical film according to any one of claims 12 to 17, wherein at least one width measurer among the plurality of width measurers has a light irradiator for irradiating light to the film. 19. The method of claim 18, wherein the conveying mechanism has a conveying roll;
The light irradiation unit irradiates light to the film on the conveyance roll,
At least one width measurer among the plurality of width measurers is, based on the difference in luminance of the reflected light of the film and the carrier roll generated by the light from the light irradiating unit to the film on the conveyance roll, the thickness of the film An apparatus for manufacturing an optical film that measures the width. The apparatus for manufacturing an optical film according to claim 18, wherein a polarizing filter is provided between the light irradiation unit and the film. The apparatus for manufacturing an optical film according to claim 17, wherein a polarizing filter is provided between the light detection unit and the film. The apparatus for manufacturing an optical film according to any one of claims 12 to 21, wherein the N processing units include at least one of a swelling processing unit, a dyeing processing unit, a crosslinking processing unit, a stretching processing unit, and a drying processing unit. .

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