WO2006106603A1

WO2006106603A1 - Method for dyeing polyvinyl alcohol film, process for producing polarizing film, and polarizing film and polarizing plate

Info

Publication number: WO2006106603A1
Application number: PCT/JP2006/304874
Authority: WO
Inventors: Masahiko Nose
Original assignee: Masahiko Nose
Priority date: 2005-04-04
Filing date: 2006-03-13
Publication date: 2006-10-12
Also published as: JP2006282918A; TW200702369A

Abstract

In order to minimize uneven dyeing observed in dyeing of a polyvinyl alcohol film (10) as a base material for a polarizing film for a liquid crystal display, a plurality of guide means provided in a dyeing liquid (12) contained in a dyeing tank (11) are constructed by cylinder-type low-pressurization dyeing liquid delivery rollers (16). In the cylinder-type low-pressurization dyeing liquid delivery roller (16), a number of dyeing liquid delivery holes (17) are provided at intervals in a periaxial direction and an axial direction on the circumferential part which faces a polyvinyl alcohol film (10). Both ends of the roller are fixed to a low-pressurization dyeing liquid feed pipe (18) or are supported rotatably through a bearing (21). The low-pressurization dyeing liquid cylinders (16) are successively disposed in a zig-zag form in upper and lower positions in a guide direction of the polyvinyl alcohol film (10), and the polyvinyl alcohol film (10) is turned around and guided in a zig-zag form so that the first and second surfaces of the polyvinyl alcohol film (10) successively face each other.

Description

Dyeing method of polyvinyl alcohol film and production method of polarizing film, and polarizing film and polarizing plate

Technical field

The present invention relates to a dyeing applied to a polyvinyl alcohol film (hereinafter abbreviated as “PVA film”) as a base material in the production of a polarizing film (polarizer) which is a main member of a liquid crystal display (LCD). Method and apparatus (dyeing method), method and apparatus for producing polarizing film including dyeing step and dyeing apparatus according to the dyeing method (manufacturing method), polarizing film produced by the method and apparatus, and the polarizing film The present invention relates to a polarizing plate to be formed. Background art

[0002] As is well known, this type of PVA film is dyed by permeating the dye solution while guiding the dye solution through the guide means having a plurality of guide rollers arranged in the dye solution. This is done by the method (see, for example, Japanese Patent Application Laid-Open No. 10-153709).

[0003] Since the penetration of the staining solution in this known staining method is natural penetration, the staining between the inside and the outside is particularly achieved by minimizing the difference between the penetration rate of the staining solution into the interior and the penetration rate to the surface. There is a limit to minimizing unevenness. For this reason, it is difficult to meet the demand for more uniform dyeing of PVA film, which is necessary for the production of a polarizing film having an even higher level of optical characteristics corresponding to the further increase in display performance of liquid crystal displays in recent years. In addition to the above, there is a problem that a part of the PVA film expands due to air bubbles partially taken in by the contact with the guide roller, and a defect such as wrinkles is formed.

Patent Document 1: Japanese Patent Application Laid-Open No. 10-153709

Disclosure of the invention

Problem that invention tries to solve

[0004] In view of the above situation and problems, the present invention particularly as a dyeing method (method and apparatus) of a PVA film, makes the permeation rate of the dyeing solution to the PVA film more uniform while guiding in the dyeing solution, While being able to minimize dyeing unevenness, PVA film To provide a film which can eliminate the local expansion due to air bubbles and prevent the occurrence of defects such as wrinkles, and a polarization film manufacturing method having more excellent optical characteristics including such a dyeing method It is an object of the present invention to provide (a method and an apparatus), a polarizing film manufactured by the manufacturing method, and a polarizing plate formed using the polarizing film.

Means to solve the problem

[0005] According to the present invention, the above-mentioned problem is basically achieved by using a plurality of guiding means in which a PVA film is placed in a staining solution as described in claims 1 and 3 of the claims. The dye film penetrates the dye solution while guiding it into the dye solution. At least one guide means is provided in the method and apparatus for dyeing a PVA film, and a large number of low pressure dye solution discharge holes are provided in the opposite part of the PVA film. This problem is solved by forming a low-pressure staining solution discharge roller of a cylinder (drum) type that supplies the low-pressure staining solution to the inside through a low-pressure staining solution supply pipe.

[0006] In the method and apparatus for dyeing a PVA film according to the present invention as set forth in claims 1 and 3, low pressure staining solution discharge constituting at least two guiding means according to claims 2 and 4 is provided. It is desirable to turn and guide the PVA film on the roller so that the front and back sides face each other.

The present invention also includes, as described in claim 5, a step of dyeing the PVA film by the method of dyeing a PVA film according to claim 1 or 2, and a drawing step after the step of dyeing. And a method of producing a polarizing film.

Furthermore, the present invention provides an apparatus for producing a polarizing film, comprising the dyeing apparatus for a PVA film according to claim 3 or 4 according to claim 6 and a stretching tank disposed after the dyeing apparatus. .

Furthermore, as described in claim 7, the present invention provides a polarizing film produced by the method or apparatus for producing a polarizing film according to claim 5 or 6, and further comprising a polarizing film according to claim 8. A polarizing plate obtained by adhering a protective film to the polarizing film according to claim 7 is provided.

Effect of the invention

[0010] According to the method and apparatus for dyeing a PVA film of the present invention as claimed in claims 1 and 3 from the dyeing solution discharge hole of the low pressure dyeing solution discharge cylinder constituting the guide means. The low pressure dyeing liquid discharged forms a low pressure dyeing liquid layer on the outer peripheral portion of the low pressure dyeing liquid discharge roller, whereby the PVA film does not contact the low pressure dyeing liquid discharge roller. As a result, there is no risk of causing defects such as wrinkles in the PVA film, and the dyeing action by natural penetration of the dyeing solution similar to the well-known case, except for the low-calorie dyeing solution discharge roller force. On the other hand, in the guide means portion which is driven by the low pressure dyeing liquid discharge roller, the low pressure dyeing liquid discharged from the large number of dye liquid discharge holes flows along the surface of the low pressure dyeing liquid discharge roller. Due to the forced staining action by low pressure penetration, these two staining actions act synergistically, so that uneven dyeing is minimized.

Further, according to the opposing guiding configuration of the front and back sides of the PVA film with respect to the two or more low pressure dyeing liquid discharge cylinders according to the second and fourth aspects, the PVA film force Due to the forced staining effect of low pressure penetration, a more uniform staining is performed.

Furthermore, according to the method and apparatus for producing an eccentric film as claimed in claims 5 and 6, since uneven dyeing is minimized, it is possible to have further excellent optical properties and to be free from defects such as wrinkles etc. Can be manufactured.

Furthermore, the polarizing film and the polarizing plate described in claims 7 and 8 both exhibit better optical properties.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the method and apparatus for dyeing a PVA film according to the present invention will be particularly described with reference to the drawings.

FIG. 1 shows the outline of the configuration of a preferred embodiment of the method and apparatus for dyeing a PVA film according to the present invention, in which a PVA film 10 is introduced into a dyeing solution 12 in a dyeing tank 11. Left force on the side A plurality (three in this case) of low-pressure staining solution discharge rollers 16 are arranged in a zigzag at the bottom and top toward the right, and the left and right portions outside the staining tank 11 The film introduction roller 13 and the guide roller 15, the guide roller 15 and the film lead-out roller 15 are installed in the film, and the force of the film introduction roller 14 is also introduced into the dyeing solution 12 in the dyeing tank 11 through the guide roller 15. The guide rollers are directed in a staggered fashion up and down so that the front and back surfaces alternately face the low-pressure staining solution discharge roller 16 sequentially, and then guide rollers outside the staining tank 11 It is constituted so that it may lead out from 15 to film taking-out roller 15. After this, the PVA film 10 is guided to a stretching tank or the like to produce a polarizing film.

FIGS. 2 and 3 schematically show two embodiments of the low-pressure staining solution discharge cylinder 16, wherein the former has a substantially semi-peripheral portion facing the PVA film 10 (in the staining tank 11, For those located on the lower side, as shown in FIG. 2, a large number of stains are discharged at intervals in the axial direction and around the axis in the lower half and the upper half. It is immobile (non-rotational type) in which holes 17 are formed, and low pressure staining solution supply pipes 18 extending horizontally at both ends are fixed.

On the other hand, the latter forms a low-pressure staining solution supply pipe 18 having a large number of staining solution discharge holes 17 formed around the entire circumference and at intervals in the axial direction and having both ends concentrically extending inside. The low-pressure staining solution supply pipe 18 is a rotary type supported via a bearing 21. The low-pressure staining solution discharge roller 16 on the side facing the PVA film 10 (shown in FIG. As for those located on the lower half side and upper side, there are multiple stain fluid supply and discharge holes 19 that are opened around the axis and in the axial direction at the upper half side), and partitions that horizontally extend both left and right sides A wing 20 is attached.

In the illustrated embodiment, in the case of using the low-pressure staining solution discharge roller 16 of either the stationary type or the rotary type, the staining in the staining tank 11 is performed via the film introduction roller 14 and the guide roller 15. The PVA film 10 introduced into the solution 12 is in the dyeing tank 11 between the first low-pressure dye solution discharge roller 16 and between the adjacent upper and lower low-pressure dye solution discharge rollers 16. Under the staining action by the natural penetration of the staining solution 12 and in the portions of the low-pressure staining solution discharge rollers 16, the low-pressure staining solution discharged outward through the staining solution discharge holes 17 Each of the back side is subjected to a forced staining action by low pressure penetration, and is appropriately stained before being discharged from the staining tank 11.

In the method and apparatus for dyeing a PVA film according to the present invention, a low pressure dyeing solution discharged through the dyeing solution discharge hole 17 of the low pressure dyeing solution discharge cylinder 16 is generally a PVA film. A condition (pressure, flow rate, flow rate, etc.) suitable for making the surface of the ILUM 11 a small amount (for example, about 1 mm) of the surface force of the low-pressure staining solution discharge cylinder 16 as well (non-contact state) Minute thickness (for example, about 1 It can be discharged under conditions suitable for forming a fluidized bed of low-pressure staining solution of about mm), and it can be used in the form of circulating the staining solution 12 in the staining tank 11.

[0020] The discharge conditions of these low-pressure staining solutions are appropriately determined depending on the size (thickness, width) of the PVA film 10, transport conditions (tension, speed, etc.), the temperature of the staining solution 12 in the staining tank 11, etc. While being able to set, the conveyance conditions of these PVA films 10, the temperature of the dyeing liquor 12, etc. can be made adjustable by automatic control.

In the method and apparatus for dyeing a PVA film according to the present invention, in addition, a low-pressure staining solution discharge roller can be rotationally driven (for example, concentric to the end of a rotary low-pressure staining solution discharge cylinder The present invention can be implemented in various forms such as attaching a driven gear and engaging a drive gear installed adjacent to the driven gear, and the present invention is not limited to the above form.

Example

[0022] A swelling tank in front of the dyeing tank, a dyeing tank in which a stationary low pressure dyeing liquid discharge roller substantially as shown in FIG. 2 is disposed substantially in accordance with FIG. Swelling, dyeing, stretching, using a stretching tank, a fixing tank, and a drying device installed after the tank, while controlling the tension and speed (1.5 mZ min), etc. of a PVA film having a width of 1100 mm and a thickness of 80. Iodine dye solution fixing and drying are performed to produce a plurality of polarizing films, and protective films are adhered to both sides of these films to form a plurality of polarizing plates. When the degree, degree of polarization and degree of cross were measured, about 43.4%, about 99.98%, and about 0.01% force were obtained as average values, respectively.

Comparative example

[0023] A PVA film of the same size as the above is obtained using the same swelling tank, stretching tank, etc. as described above, together with a dyeing tank in which a standard guide roller is disposed instead of the low pressure dyeing liquid discharge roller. The film is treated with swelling, dyeing, stretching, etc. under substantially the same conditions as above to produce a plurality of polarizing films, and the single transmittance, the polarization and the cross ratio are measured for a plurality of polarizing plates thus formed. The average value of each was about 42.5%, about 99. 96%, about. It was 03%.

Brief description of the drawings FIG. 1 is a schematic configuration view of an embodiment of a method and apparatus for dyeing a PVA film according to the present invention.

2) A schematic enlarged side sectional view of an embodiment of a low pressure staining solution discharge cylinder, showing a state of being installed in the lower part of the staining tank together with the PVA film.

FIG. 3 is a view similar to FIG. 2 of another embodiment of a low pressure staining solution discharge cylinder.

Explanation of sign

10 PVA film

11 Staining tank

12 Staining solution

13 Film introduction roller

14 Film Guide Roller

15 Guide rollers

16 Low-pressure staining solution discharge roller

17 Dyeing hole

18 Low pressure staining solution supply pipe

19 Dyeing solution supply and discharge hole

20 partition plate

21 bearings

Claims

The scope of the claims

[1] A method of dyeing a polyvinyl alcohol film in which a staining solution permeates while guiding the dyeing solution through a plurality of guiding means in which the polyvinyl alcohol film is placed in the staining solution, at least one guiding means A cylinder-type low-pressure dye solution discharge roller that has a large number of low-pressure dye solution discharge holes on the opposite side of the polyvinyl alcohol film and supplies low-pressure dye solution to the inside through a low-pressure dye solution supply pipe. A method of dyeing polybule alcohol film, characterized in that it comprises.

[2] The polyvinyl alcohol film according to claim 1, characterized in that the polyvinyl alcohol film is diverted and guided to the low pressure staining solution discharge rollers constituting at least two guide means so that the front surface and the back surface face each other. How to dye film.

[3] A dyeing apparatus for polyvinyl alcohol film in which a staining solution permeates while guiding the inside of the staining solution through a plurality of guide means in which the polyvinyl alcohol film is placed in the staining solution, at least one guide means A cylinder-type low-pressure dye solution discharge roller that has a large number of low-pressure dye solution discharge holes on the opposite side of the polyvinyl alcohol film and supplies low-pressure dye solution to the inside through a low-pressure dye solution supply pipe. An apparatus for dyeing polyvinyl alcohol film, characterized in that it comprises.

[4] The polyvinyl alcohol film according to claim 3, characterized in that the polyvinyl alcohol film is diverted and guided to the low pressure staining solution discharge rollers constituting at least two guide means so that the front and back surfaces face each other. Film dyeing equipment.

[5] A method for producing a polarizing film, comprising the steps of dyeing a polybule alcohol film by the method of dyeing polybule alcohol film according to claim 1 or 2, and a stretching step after the dyeing step.

[6] An apparatus for producing a polarizing film, comprising the polyvinyl alcohol film dyeing apparatus according to claim 3 or 4 and a stretching tank disposed after the dyeing apparatus.

[7] A polarized fluorescent material produced by the method or apparatus for producing a polarizing film according to claim 5 or 6.

[8] A polarizing plate formed by adhering a protective film to the polarizing film according to claim 7.