JP2008238679A - Method for jointing polymer film and method for stretching polymer film using this joint method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the breakage of a TAC film and a joint tape when they are off-line stretched. <P>SOLUTION: A rear end notch 3c is formed in the rear end part of a preceding film 3a, and a tip notch 3d is formed in the tip part of a succeeding film 3b. Each notch 3c or 3d, when a clip 15 is positioned in each notch 3c or 3d, is formed in such a size that the TAC film 3 can not be gripped by the clip 15. The corner parts of each notch are formed approximately in the shape of an arc. The rear end part of the preceding film and the tip part of the succeeding film are jointed together by the joining tape 41. A part jointed by the joining tape 41 of the TAC film 3 is not stretched in a tenter part 5. During stretching in the tenter part 5, the joint of the TAC film 3 and the joint tape 41 are not broken. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for joining a polymer film used in an off-line stretching apparatus, and a method for stretching a polymer film using the same.

  In recent years, due to the rapid development and spread of liquid crystal displays and the like, the demand for cellulose acylate films, particularly triacetyl cellulose films (TAC films) used as protective films for these liquid crystal displays is increasing. With this increase in demand, improvement in productivity is desired. The TAC film is supported by casting a dope containing a TAC and a solvent on a continuously running support using a casting die, and providing the casting film with self-supporting property by drying or cooling. It is manufactured by peeling off from the body, drying and winding up. In such a solution casting method, a film having no foreign matter and excellent optical characteristics can be obtained as compared with a film forming method by melt extrusion.

  In the solution casting method, the support for receiving the dope includes a band and a drum. The drum system is easier to improve the casting speed than the band. Moreover, in order to give self-supporting property on a support body, methods, such as acceleration | stimulation of drying and cooling gelation, are used. On the other hand, stretching is carried out as a method for adjusting the optical properties of the TAC film, particularly the retardation.

However, the optimum speed is different between the film forming speed and the stretching speed, and the film forming speed is a rule. Therefore, if the film forming speed is matched with the film forming speed, it is not possible to sufficiently perform stretching for improving the optical characteristics. Therefore, it has been proposed to perform off-line stretching separately from the solution casting line (see, for example, Patent Document 1).
JP 2002-311240 A

  By the way, as described in Patent Document 1, when stretching off-line separately from the solution casting line, it is preferable to continuously stretch in order to perform stretching efficiently. In this case, it is conceivable to join the leading edge of the succeeding film to the trailing edge of the preceding film. However, the TAC film has a high rigidity, and when joined, the thickness of the joining portion increases and the rigidity is further increased. It will go up. When a non-uniform portion of rigidity occurs due to such joining, the TAC film may be damaged at the portion during stretching, which has been a new problem. For this reason, every time a new TAC film is set in the offline stretching apparatus, it is necessary to set a new TAC film after the trailing end of the preceding TAC film exits the offline stretching apparatus, resulting in a reduction in work efficiency. . In addition, since the tip of the TAC film needs to be bitten into the clip each time it is set, there is also a problem that it takes time to set. Such a problem exists not only in the TAC film but also in other polymer films.

  The present invention has been made to solve the above problems, and a method for joining a polymer film in which the polymer film and the joining tape are not damaged when the polymer film is stretched off-line, and a polymer using the same. It aims at providing the extending | stretching method of a film.

  In order to achieve the above object, the polymer film joining method of the present invention is used in a stretching apparatus that stretches in the film width direction while gripping and conveying both side edges of the polymer film with a plurality of clips, and the stretching apparatus In the method for joining a polymer film, a leading edge of a second polymer film that follows is joined to a trailing edge of a preceding first polymer film in order to continuously feed the polymer film to the first polymer film. A joining step for joining a rear end of the second polymer film and a tip of the second polymer film, and a grip for removing a grip region portion by the clip at a joint portion between the first polymer film and the second polymer film A non-gripable region forming step of forming the non-capable region.

  In addition, a notch is formed by notching a gripping region portion by the clip at both side edges of the rear end portion of the first polymer film and both side edges of the front end portion of the second polymer film. It is preferable to form the non-gripable region by a notch.

  The length of the cutout in the film transport direction is appropriately changed according to the size of the clip and the interval at which the plurality of clips are arranged, and the cutout is formed by cutting the clip into the cutout. The distance from the side end of the clip in the film transport direction is 10 to 100 mm, and the distance from the inner end of the clip in the film stretching direction is 10 to 100 mm. preferable.

  Furthermore, it is preferable that the notch is formed in a substantially rectangular shape with corners having a substantially arc shape. In addition, as said substantially circular arc shape, it is preferable that it is a curvature radius of 10 mm or more, and it is more preferable that it is a curvature radius of 30 mm or more.

  Moreover, it is preferable that the said joining process joins said 1st polymer film and said 2nd polymer film using a joining tape. Examples of the bonding tape include a baseless double-sided tape using an acrylic adhesive.

  Furthermore, it is preferable that the joining step is performed using a joining film that is narrower than the first polymer film and the second polymer film, and that forms the non-gripable region by the narrow portion.

  Further, the polymer film stretching method of the present invention is characterized in that the polymer film joined by the polymer film joining method is sent to the stretching device to perform continuous stretching.

  According to the polymer film joining method of the present invention, the non-gripable region for removing the grip region portion by the clip is formed in the joint portion between the preceding first polymer film and the following second polymer film. The joint portion of the polymer film is not damaged during stretching. Thereby, a some polymer film can be extended | stretched continuously.

  Moreover, since the notch was formed in the both side edges of the rear end part of the first polymer film and the both side edges of the tip part of the second polymer film, the clip does not grip both side edges of the joint part, The joint portion of the polymer film is not damaged during stretching.

  Furthermore, since the notch is formed in a substantially rectangular shape with a substantially arc shape at the corner, breakage of the notch corner due to stress concentration at the notch corner during stretching (notch) Can be prevented.

  In addition, according to the method for stretching a polymer film of the present invention, the polymer film joined by the polymer film joining method is continuously stretched by a stretching apparatus, so that the polymer film can be continuously stretched without being damaged. .

  As shown in FIG. 1, the offline stretching apparatus 2 stretches the TAC film 3, and includes a supply chamber 4, a tenter unit 5, a thermal relaxation chamber 6, a cooling chamber 7, and a winding chamber 8. Prepare. The supply chamber 4 stores a roll-formed TAC film 3 manufactured by a solution casting apparatus. The supply roller 9 supplies the TAC film 3 to the tenter unit 5.

  The TAC film 3 sent to the tenter unit 5 is heated while being gripped and conveyed by the clips 15 (see FIG. 2), and the TAC film 3 is stretched in the film width direction B (see FIG. 2). . The tenter unit 5 preferably extends the TAC film 3 by 100.5% to 300% in the width direction.

  A reservoir 10 is provided between the supply chamber 4 and the tenter unit 5. In the reservoir 10, a TAC film 3 is sent out to the tenter unit 5 after forming a loop for a time required for a film bonding process described later.

  As shown in FIG. 2, the tenter unit 5 conveys the TAC film 3 in the film conveyance direction A and extends in the film width direction B. The first rail 11, the second rail 12, and the rails 11 , 12 are provided with first and second chains (endless chains) 13, 14. The inside of the tenter unit 2 is maintained at a high temperature. Further, if necessary, the tenter unit 5 may divide a plurality of zones in the film transport direction A and change the film heating conditions for each zone. For example, a preheating zone, a heating zone, and a thermal relaxation zone may be provided in order in the film conveyance direction A.

  A number of clips 15 are attached to the first and second chains 13 and 14 at regular intervals. The clip 15 extends along the film width direction B by moving along the rails 11 and 12 while holding the side edge of the TAC film 3. In this embodiment, when the width of the TAC film 3 before stretching is 100%, the stretched width is stretched to be 103%. However, the stretch ratio is not limited to this, and the stretch ratio is desired. It is appropriately changed according to the optical characteristics and the like.

  The first and second chains 13 and 14 are spanned between the driving sprockets 21 and 22 and the driven sprockets 23 and 24, and the first chain 13 is connected by the first rail 11 between these sprockets 21 to 24. The second chain 14 is guided by the second rail 12. The driving sprockets 21 and 22 are provided on the tenter outlet 27 side, these are rotationally driven by a driving mechanism (not shown), and the driven sprockets 23 and 24 are provided on the tenter inlet 26 side.

  As shown in FIG. 3, the clip 15 includes a clip body 31 and a rail attachment portion 32. The clip main body 31 includes a substantially U-shaped frame 33 and a flapper 34, and the flapper 34 is rotatably attached to the frame 33 by an attachment shaft 33a. The flapper 34 has a film gripping position (closed position) where the flapper 34 is in a vertical state (see FIG. 5) and an open position (see FIG. 3) where the engaging head 34a is in contact with the opening member 40 and rotated obliquely. Usually, the film is urged so as to reach the film gripping position by its own weight. At the film gripping position PA, the TAC film 3 is gripped by the film gripping surface 33b and the flapper lower surface 34b.

  The rail attachment portion 32 includes an attachment frame 35 and guide rollers 36, 37, and 38. The first chain 13 or the second chain 14 is attached to the attachment frame 35. The guide rollers 36 to 38 rotate in contact with the support surfaces of the driving sprockets 21 and 22 or in contact with the support surfaces of the first rail 11 or the second rail 12. Thus, the clip body 31 is guided along the rails 11 and 12 without dropping from the sprockets 21 and 22 and the rails 11 and 12.

  An opening member 40 of the clip 15 is disposed in the vicinity of the sprockets 21 to 24. In the driven sprockets 23, 24 of the tenter inlet 26, the opening member 40 contacts the engagement head 34 a of the clip 15 before the film gripping position PA to open it, and the side edge of the TAC film 3. To accept. Then, when passing through the film gripping position PA, the release member 40 is separated from the engaging head 34a, the clip 15 is set from the open position to the gripping position, and the side edge of the TAC film 3 is gripped. Similarly, in the driving sprockets 21 and 22 of the tenter outlet 27, the clip 15 is opened to the open position by the release member 40 at the grip release position PB of the TAC film 3, and the grip of the side edge portion of the TAC film 3 is released. .

  As shown in FIGS. 4 and 5, in order to continuously stretch the TAC film 3 in the tenter unit 5, the rear end of the TAC film (previous film) 3a set in the supply chamber 4 and a new TAC film (Following film) The front end portion of 3b is joined by a joining tape 41 made of an adhesive tape. As a joining method, it joins with the joining tape 41 in the state which accumulated the surface of the rear-end part of the preceding film 3a, and the surface of the front-end | tip part of the succeeding film 3b. The joining tape 41 is made of polyester. In addition, you may make it also join the back surface of each TAC film 3 with the joining tape 41. FIG.

  A rear end notch (notch) 3c is formed on both side edges of the rear end of the preceding film 3a, and a front end notch (notch) 3d is formed on both side edges of the front film 3b. ing. Each notch 3c, 3d is formed in such a size that the TAC film 3 cannot be gripped by the clip 15 when the clip 15 is positioned in each notch 3c, 3d. The corners of the notches 3c and 3d are formed in a substantially arc shape (curvature radius R = 30 mm) in order to relieve stress during stretching. As a method of forming the rear end notch 3c and the front end notch 3d, the rear end notch 3c and the front end notch 3d may be formed by a machine or manually.

  As shown in FIG. 6, when the clip 15 is positioned in the rear end notch 3c, the rear end notch 3c has a distance D1 = 30 mm from the right end of the clip 15 in the film transport direction A, and the film width direction. The distance D2 from the inner end (the upper end or the lower end in FIG. 6) of the clip 15 in B is set to be 70 mm. Further, the rear end notch 3c is such that the film width W1 and the width W2 of the portion where the film width is narrowed by the rear end notch 3c are 0.6 × W1 ≦ W2 ≦ 0.9 × W1. Is formed.

  The leading edge notch 3d has a distance D3 = 30 mm from the left end of the clip 15 in the film transport direction A when the clip 15 is positioned in the leading edge notch 3d, and the inner edge of the clip 15 in the film width direction B (see FIG. 6, the distance D4 from the upper end or the lower end) is 70 mm. The leading edge notch 3d is formed such that the film width W1 and the width W3 of the portion where the film width is narrowed by the leading edge notch 3d are 0.6 × W1 ≦ W3 ≦ 0.9 × W1. ing.

  When joining the rear end portion of the preceding film 3a and the leading end portion of the succeeding film 3b with the joining tape 41, first, as shown in FIG. It puts on the front-end | tip part of the film 3b, and the overlapped part is joined by the joining tape 41 (refer FIG. 5). When the TAC film 3 is bonded, the TAC film 3 stored in the reservoir 10 is conveyed to the tenter unit 5, so that the TAC film 3 can be bonded without stopping the tenter unit 5. This joining may be automatically performed by a machine, or may be performed manually in the case of a simple system. Moreover, you may make it join in the state which faced | matched the rear end of the preceding film 3a, and the front-end | tip of the following film 3b, without overlapping the leading film 3a and the following film 3b.

  In addition, after joining the rear-end part of the preceding film 3a in which the rear-end notch 3c is not formed, and the front-end part of the succeeding film 3b in which the front-end notch 3d is not formed by the joining tape 41, the rear end notch You may make it form the notch 3c and the front-end | tip notch 3d.

  The TAC film 3 is stretched while being gripped by the clips 15 and conveyed. As shown in FIGS. 5 and 6, when the TAC film 3 is stretched by the tenter unit 5, the rear end cutout 3 c of the preceding film 3 a and the front end cutout 3 d of the subsequent film 3 b are gripped by the clip 15. There is nothing to do. The part joined by the joining tape 41 of the TAC film 3 is not stretched by the tenter part 5, and the joining part of the TAC film 3 and the joining tape 41 are not damaged at the time of stretching by the tenter part 5. Thereby, the TAC film 3 can be continuously stretched.

  In order to continuously stretch the TAC film 3, it is necessary to insert the gripping tip 3e gripped by the clip 15 of the succeeding film 3b into the clip 15 (put it on the film gripping surface 33b of the frame 33). There is. When the gripping tip portion 3e is weak and hangs down, the gripping tip portion 3e does not enter the clip 15. Therefore, the gripping tip portion 3e is provided with an adhesive tape (not shown) for increasing the rigidity. It is pasted. In addition, instead of sticking the adhesive tape, the outer width side arcuate part is formed closer to the rear end side than the present embodiment, and the gripping tip part 3e is bent to increase rigidity, and the inner width side arcuate shape is formed. The gripping tip 3e may be surely inserted into the clip 15 by, for example, forming a taper from the portion to the arcuate portion on the outer width side to prevent sagging.

  As shown in FIG. 1, the TAC film 3 is stretched by the tenter unit 5 and then sent out to the ear clip device 42. Both edges of the TAC film 3 are cut by the edge-cutting device 42 and the cut side edges are sent to the crusher 43 by a cut blower (not shown). By the crusher 43, the side edge is crushed into chips. Since this chip is reused for dope preparation, this method is effective in terms of cost. The TAC film 3 whose both edges have been cut by the ear clip device 42 is sent to the thermal relaxation chamber 6.

  The heat relaxation chamber 6 is provided with a large number of rollers 44, and the TAC film 3 is conveyed through the heat relaxation chamber 6 by the rollers 44 to be heat relaxed, and then sent to the cooling chamber 7. In the heat relaxation chamber 6, wind at a desired temperature is blown from a blower (not shown). The temperature of the wind at this time is preferably 20 ° C to 250 ° C.

  After the thermal relaxation, the TAC film 3 is cooled to 30 ° C. or lower in the cooling chamber 7 and then sent to the winding chamber 8. Inside the winding chamber 8, a winding roller 45 and a press roller 46 are provided. The TAC film 3 sent to the winding chamber 8 is wound up by a winding roller 45. At this time, it is pressed by the press roller 46 and wound up.

  Instead of forming the rear end cutout 3c in the preceding film 3a and the front end cutout 3d in the following film 3b, as shown in FIGS. 7 and 8, the rear end and the rear end of the preceding film 3a are shown. You may make it join the front-end | tip of the row film 3b with the joining film 47 and the joining tape 48 in the state which left the clearance gap.

  The bonding film 47 is composed of a base material made of the same material as the TAC film 3, and is formed to be narrower than the TAC film 3. As shown in FIG. 7A, the rear end of the preceding film 3a and the front end of the succeeding film 3b are arranged with a gap left therebetween. Then, as shown in FIG. The bonding film 47 is placed on the rear end portion of the preceding film 3a and the front end portion of the subsequent film 3b. In this state, the surface of the bonding film 47 and the surface of the TAC film 3 are bonded by the bonding tape 48. The bonding film 47 is formed to be narrower than the TAC film 3, and the gap between the rear end portion of the preceding film 3 a and the front end portion of the subsequent film 3 b is a region covered with the bonding film 47 and the bonding film 47. Is divided into an uncovered area 49 which is an area not covered by the. Note that the back surface of the bonding film 47 and the back surface of the TAC film 3 may be bonded by the bonding tape 48.

  As shown in FIG. 8, the bonding film 47 is a distance from the inner end (the upper end or the lower end in FIG. 6) of the clip 15 in the film width direction B when the clip 15 is positioned in the uncovered region 49. D5 = 70 mm, distance D6 = 30 mm from the right end of the clip 15 in the film transport direction A to the rear end of the preceding film 3a, distance D7 = from the left end of the clip 15 in the film transport direction A to the front end of the subsequent film 3b It is formed to be 30 mm and is joined to the TAC film 3. The bonding film 47 is formed such that the film width W4 and the film width W1 are 0.6 × W1 ≦ W4 ≦ 0.9 × W1. In the present embodiment, the non-covering region 49 is a non-gripable region that is not gripped by the clip 15.

  Further, without using the bonding film 47, only the bonding tape 48 formed in the same size as the bonding film 47 is used to bond the rear end of the preceding film 3a and the front end of the subsequent film 3b with a gap therebetween. In addition, an uncovered region 49 may be formed.

  The TAC film 3 only needs to be manufactured by a known solution casting method, and for example, a TAC film described in JP-A-2005-104148 can be used. In particular, in order to improve the film forming speed, a dope containing TAC and a solvent is cast on the peripheral surface of a cooled casting drum, and the cast film is cooled and gelled to be self-supporting. The TAC film having excellent optical characteristics can be produced efficiently and without waste by carrying out the present invention with respect to the TAC film that has been taken and dried through the pin tenter.

  In addition, although this embodiment demonstrated using the TAC film 3 as a polymer film, this invention is applicable to various polymer films, without being limited to the TAC film 3. FIG.

It is a top view which shows an offline extending | stretching apparatus. It is a top view which shows a tenter part. It is a side view which shows a clip. It is a perspective view which shows a preceding film, a subsequent film, and a joining tape. It is a perspective view which shows a preceding film, a succeeding film, a joining tape, and a clip. It is a top view which shows a preceding film, a succeeding film, a joining tape, and a clip. It is a perspective view which shows a preceding film, a subsequent film, a joining film, and a joining tape. It is a top view which shows a preceding film, a subsequent film, a joining film, a joining tape, and a clip.

Explanation of symbols

2 Off-line stretching device 3 TAC film 3a Leading film 3b Trailing film 3c Notch at rear end (notch)
3d Tip notch (notch)
5 Tenter 15 Clip 41 Bonding Tape 47 Bonding Film 48 Bonding Tape 49 Non-covering Area (Ungripping Area)

Claims (6)

A first polymer used in a stretching apparatus that stretches in the film width direction while gripping and conveying both side edges of the polymer film with a plurality of clips, and continuously feeding the polymer film to the stretching apparatus. In the method for joining polymer films, in which the leading end of the second polymer film to be followed is joined to the rear end of the film.
A bonding step of bonding a rear end of the first polymer film and a front end of the second polymer film;
A non-gripable region forming step for forming a non-gripable region for removing a grippable region portion by the clip at a joint portion between the first polymer film and the second polymer film; Film joining method.   A notch is formed by notching a gripping region portion by the clip at both side edges of the rear end portion of the first polymer film and both side edges of the front end portion of the second polymer film. 2. The polymer film joining method according to claim 1, wherein the non-gripable region is formed.   3. The polymer film joining method according to claim 2, wherein the notch is formed in a substantially rectangular shape with a corner portion having a substantially arc shape.   The method for joining polymer films according to any one of claims 1 to 3, wherein in the joining step, the first polymer film and the second polymer film are joined using a joining tape.   The bonding step is performed using a bonding film that is narrower than the width of the first polymer film and the second polymer film, and that forms the non-gripable region by the narrow portion. The method for joining polymer films described in the above.   A method for stretching a polymer film, wherein the polymer film joined by the polymer film joining method according to any one of claims 1 to 5 is sent to the stretching device to perform continuous stretching.

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