JP2006199722A - Method and apparatus for swelling polyvinyl alcohol film and method and apparatus for producing polarizing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for swelling a polyvinyl alcohol film as a substrate with swelling water in the production of a polarizing film being a main member of a liquid crystal display, with which the whole polyvinyl alcohol film is more uniformly swollen and the yield of a polarizing film is further increased. <P>SOLUTION: Guide rollers composed of a plurality of pressurized water discharge rollers 15 having pressurized water discharge holes opening symmetrically in both the axial directions in the conveying guide direction of a polyvinyl alcohol film 10 are arranged zigzag at the upper part and the lower part in swelling water 12 in a swelling tank 11 and the polyvinyl alcohol film 10 is vertically zigzag conveyed and guided so as to make the surface and the back of the film alternately and successively oppose against the pressurized water discharged rollers 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    This invention is based on swelling water applied to a polyvinyl alcohol film (hereinafter referred to 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). It relates to an improvement of the swelling method.

  As is well known, this type of PVA film is swelled by conveying and guiding the swollen water through a plurality of guide rollers in which the PVA film is placed in the swollen water (for example, see Patent Document 1).

However, since this well-known swelling method of PVA film is swelling by natural penetration of the swelling water into the PVA film, as the PVA film becomes wider as in recent years, unevenness in the penetration of the swelling water occurs. It is difficult to uniformly swell the whole, and as a result, post-swelling treatments (dyeing, stretching, etc.) are difficult to perform uniformly, uneven optical properties as a polarizing film are likely to occur, and yield as a polarizing film (yield) ) Remains at a relatively low value, such as about 75% or less.
JP-A-10-153709

  In view of the situation as described above, the present invention is a method for swelling a PVA film that guides the swollen water through a plurality of guide rollers in which the PVA film is placed in a swelling liquid. Thus, the main object is to provide a polarizing film that can further increase the yield of the polarizing film.

  According to this invention, the above-mentioned problem is basically guided in the swollen water through the plurality of guide rollers in which the PVA film is placed in the swollen water, as described in claim 1 of the claims. In the swelling method of the PVA film, at least one guide roller is constituted by a cylinder (drum) type pressurized water discharge roller in which a large number of pressurized water discharge holes are formed symmetrically on both halves in the axial direction.

  In the method for swelling the PVA film of the sheet according to the first aspect of the present invention, as described in the second aspect, the PVA film is opposed to the pressurized water discharge roller constituting at least two guide rolls, and the front surface and the rear surface are opposed to each other. It is desirable to guide the turning as described above.

  Further, in the method for swelling a PVA film according to claim 1 or 2 according to the present invention, as described in claim 3, the pressurized water discharge hole of the pressurized water discharge roller is arranged around the axis of the surface portion of the pressurized water discharge roller. It is desirable to form it so that it may open to each of the pressurized water guide groove extended in the axial direction of the plurality of strips formed at intervals.

  Furthermore, in the swelling method of the PVA film according to claim 3 of the present invention, as described in claim 4, the axial position of the pressurized water discharge hole in the pressurized water guide groove adjacent to the pressurized water discharge roller can be shifted from each other. preferable. In this case, the shift amount of the position can generally be a half pitch.

  Furthermore, in the swelling method of the PVA film according to any one of claims 1 to 4, as described in claim 5, it is desirable that the pressurized water discharge roller is supported by a water supply end portion (tip portion) of the pressurized water supply pipe system. .

  According to the basic structure of the swelling method of the PVA film according to the present invention as set forth in claim 1, the entire film is swelled almost uniformly, and the yield of the polarizing film is increased to a level exceeding 90%. Confirmed that it will be. Such a high yield is due to the fact that the PVA film introduced into the swollen water is subjected to a swelling action by natural permeation of the swollen water in the same manner as the known method, except for the guide roller comprising the pressurized water discharge roller. In the guide roller section consisting of the discharge roller, it is forced to swell due to the pressurization and penetration of pressurized water discharged from a number of pressurized water discharge holes and flowing along the surface of the roller. It is estimated that

  Moreover, according to the opposing guide structure of the front and back surfaces of the PVA film with respect to the two or more pressure swelling water discharge rollers according to claim 2, the PVA film has a forced swelling action by pressure water penetration from both surfaces. In response, the swelling is more uniform.

  According to the opening structure with respect to the pressurized water guide groove of the pressurized water discharge hole of the pressurized water discharge roller according to claim 3, since the pressurized water flows toward each end in the axial direction along the pressurized water guide groove, the PVA film has a widening action. Since there is no wrinkle or sagging, swelling is more uniform.

  Furthermore, according to the axial position shift configuration such as the half pitch of the pressurized water discharge holes in the adjacent pressurized water guide grooves according to claim 4, the discharge portion of the pressurized water is in a more balanced state. It becomes uniform and the PVA film is subjected to a uniform widening action, so that nearly uniform swelling is ensured.

  Furthermore, according to the support structure by the water supply end part of the pressurized water supply pipe system of the pressurized water discharge roller according to claim 5, it is not necessary to provide an independent support shaft, so that the structure can be made compact.

  Hereinafter, preferred embodiments of the method for swelling a PVA film according to the present invention will be described with reference to the drawings.

  FIG. 1 shows an outline of the configuration of a preferred embodiment of the method for swelling a PVA film according to the present invention. In the swelling water 12 in the swelling tank 11, the PVA film 10 is introduced from the left side to the right side. A plurality (four in this case) of pressurized water discharge rollers 15 and one standard conventional guide roller 16 are disposed in a staggered manner at the lower and upper portions, and the left side outside the swelling tank 11 On the right side, a film introduction roller 17, a standard guide roller 18 and a film outlet roller 19 are installed, and the PVA film 10 introduced into the swelling water 12 in the book water tank 11 through the film introduction roller 17, After sequentially guiding the front and back surfaces in a zigzag manner so that the front surface and the back surface alternately face the pressurized water discharge roller 15, a standard guide roller 18 outside the swelling tank 11 is passed through the guide roller 16. 19, which was configured so as to derive to.

  As shown in FIGS. 2 and 3, each pressurized water discharge roller 15 has a plurality of pressurized water guide grooves 20 formed at equal intervals around the axis on the surface portion. A plurality of outwardly open pressurized water discharge holes 21 are opened at substantially equal intervals at positions symmetrical with respect to the center in the axial direction. The pressurized water discharge holes 21 are opened at positions shifted by a half pitch in the adjacent pressurized water guide grooves 20 and are arranged in a staggered manner as a whole.

  Each of the pressurized water discharge rollers 15 has a pair of left and right water supply end pipe connectors (water supply end pipes) that constitute the water supply end portion of the pressurized water supply pipe system 24 together with the water supply end pipe 25 with the left and right end walls 22 extending concentrically. A connecting pipe 26 is rotatably supported via a bearing 27.

  As for the water supply end pipe 25, as for the pressure water discharge roller 15 located on the lower side in FIG. 1, as for the pressure water discharge roller 15 located on the lower half as shown in FIGS. A large number of water supply holes 28 are formed in the upper half (corresponding to the state in which the top and bottom of FIGS. 2 and 3 are inverted) and spaced around the axis and in the axial direction. In order to suppress the inflow of pressurized water into each of the upper half (see FIGS. 2 and 3) and the lower half where the water supply holes 28 are not formed, a pair of front and rear pressurized water inflow suppression flanges extending over the entire length in the axial direction 29 is attached.

  In the illustrated embodiment, the PVA film 10 introduced into the swelling water 12 in the swelling tank 11 via the film introduction roller 17 is in the upper and lower sides until reaching the first pressurized water discharge roller 15. Between the pressurized water discharge rollers 15, the water is subjected to a swelling action due to natural penetration of the swelling water 12 in the swelling tank 11, and in each of the pressurized water discharge rollers 15, the pressurized water discharged outwardly through the pressurized water discharge holes 21. By the flow along the pressurized water guide groove 20, while being subjected to a widening action, it is subjected to a forced swelling action by pressure permeation from each of the front surface and the back surface, thereby leading out from the swelling tank 11 through a conventional guide roller 16. It is swollen accurately.

  In the method for swelling the PVA film according to the present invention, the pressurized water discharged through the pressurized water discharge hole 21 of the pressurized water discharge roller 15 is generally separated from the surface of the pressurized water discharge roller 15 by a minute amount (for example, about 1 mm). The pressure water flow layer having a minute thickness (for example, about 1 mm) between the PVA film and the surface of the pressure water discharge roller is suitable for the non-contact condition (pressure, flow rate, flow rate, etc.). It is possible to discharge under conditions suitable for formation (see particularly FIG. 4).

  These discharge conditions for the pressurized water can be appropriately set according to the size (thickness, width) of the PVA film 10 and the transport conditions (tension, speed, etc.), the temperature of the swelling water 12 in the swelling tank 11, and the like. The conveyance conditions of these PVA films 10 and the temperature of the swelling water 12 can be adjusted by automatic control.

  In addition, the PVA film swelling method according to the present invention is configured such that the pressurized water discharge roller can be rotationally driven (for example, a concentric driven gear is attached to the end wall of the pressurized water discharge roller and is installed adjacent to the driven gear). Of course, the present invention is not limited to the above-described embodiments.

  Using a dyeing tank, a stretching tank, a fixing tank, and a drying device together with a swelling tank in which a pressurized water discharge roller having a structure as shown in FIGS. When a PVA film having a width of 2600 mm and a thickness of 80 μm was subjected to swelling, dyeing, stretching, dyeing agent fixing, and drying treatment while controlling the tension and speed, etc., a plurality of polarizing films were produced. As an average yield of about 90%.

  For comparison, instead of the pressurized water discharge roller, the same size PVA film as above is used together with a swelling tank in which a standard guide roller is arranged, and the same dyeing tank, stretching tank, and the like. When a plurality of polarizing films were produced by carrying out treatments such as swelling, dyeing and stretching under substantially the same conditions, the average yield of the polarizing film was about 70%.

It is a structure schematic diagram of one Embodiment of the swelling method of the PVA film which concerns on this invention. 2 is a schematic enlarged front view of an embodiment of a water supply end portion of a pressurized water supply pipe system that supports a pressurized water discharge roller located on the lower side and the pressurized water roller in the embodiment shown in FIG. FIG. 3 is a schematic cross-sectional side view of the embodiment shown in FIG. 2 where a PVA film is also shown. FIG. 3 is an enlarged front sectional view of a surface layer portion at a central portion in the axial direction of the pressurized water discharge roller shown in FIG. 2, and shows a discharge state and a flow state of the pressurized water and a separated state from the surface portion of the pressurized water discharge roller of the PVA film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 PVA film 11 Swelling tank 12 Swelling water 15 Pressurized water discharge roller 16 Guide roller 17 Film introduction roller 18 Guide roller 19 Film extraction roller 20 Pressurized water guide groove 21 Pressurized water discharge hole 22 End wall 24 Pressurized water supply pipe system 25 Feed water end pipe 26 Feed water end Pipe connector 27 Bearing 28 Water supply hole 29 Pressurized water inflow suppression flange

Claims (5)

  A method of swelling a polyvinyl alcohol film that guides the swollen water through a plurality of guide rollers in which the polyvinyl alcohol film is placed in the swollen water, and discharges a plurality of pressurized water symmetrically to both halves in the axial direction. A method for swelling a polyvinyl alcohol film, comprising a cylinder-shaped pressurized water discharge roller having a hole.   The method for swelling a polyvinyl alcohol film according to claim 1, wherein the polyvinyl alcohol film is turned and guided to a pressurized water discharge roller constituting at least two guide rolls so that the front surface and the back surface face each other.   The polyvinyl alcohol according to claim 1 or 2, wherein a pressurized water discharge hole of the pressurized water discharge roller is opened in each of a plurality of axially extending pressurized water guide grooves formed on the surface of the pressurized water discharge roller at intervals around the axis. How to swell the film.   The swelling method of the polyvinyl alcohol film of Claim 3 which mutually shifts the position of the axial direction of the pressurized water discharge hole in the pressurized water guide groove which adjoins a pressurized water discharge roller.   The swelling method of the polyvinyl alcohol film in any one of Claims 1-4 which supports a pressurized water discharge roller in the water supply end part of a pressurized water supply pipe system.

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