JP5704759B2 - Polymer film - Google Patents

Description

  The present invention relates to a polymer film, and more particularly to a polymer film in which knurling is formed at both ends of the film width.

  Polymer films are widely used as optical films and the like because of their features such as excellent light transmittance, flexibility, and light weight thinning. Among them, cellulose ester films using cellulose acylate and the like are optical films such as a protective film for a polarizing plate and a retardation film, which are constituent members of liquid crystal display devices whose market is expanding in recent years, including photographic photosensitive films. Used in film.

  As a method for producing a polymer film, a melt film forming method, a solution film forming method, and the like are known. According to these production methods, a band-shaped polymer film can be obtained.

  From the handling point of the obtained polymer film, the obtained belt-like polymer film is stored and transported in the state of a film roll. The film roll is obtained by pressing the obtained band-shaped polymer film against the winding core and winding it.

  In order to prevent winding deviation and loosening of the polymer film in the film roll, it is known to provide knurling in advance at both ends in the film width direction (hereinafter referred to as ears) using a knurling roller pair. For example, Patent Document 1 discloses that a frustum-shaped knurling having a height of 5 μm to 20 μm is provided at the ear.

JP 2005-298196 A

  However, the truncated pyramid-shaped knurling as in Patent Document 1 has a flat knurling tip. Therefore, when the polymer film is wound around the pass roller, the effect of removing air is small, and the slip occurs on the pass roller, resulting in the polymer film. There was a problem that scratches would occur.

  The present invention has been made in view of such circumstances, and provides a polymer film in which knurling capable of preventing the polymer film from slipping and generating scratches on the pass roller is formed at both ends of the film width. For the purpose.

In order to achieve the above object, the present invention provides a polymer film in which a knurling is formed at both ends of a film width, the knurling has a convex portion, and the tip curvature radius of the convex portion is 1 μm or more and 3 μm. It has the convex part which is the following, and the convex part whose front-end | tip curvature radius of this convex part is 5 micrometers or more, It is characterized by the above-mentioned.

  Protruding portions are formed, and the knurling that makes the tip curvature radius of the projecting portions 1 μm or more and 3 μm or less is formed at both ends of the film width, thereby improving the air removing effect between the polymer film and the pass roller. Therefore, since the polymer film is conveyed without slipping with the pass roller, there is almost no scratch.

  Moreover, since it has the convex part whose front-end | tip curvature radius of a convex part is 5 micrometers or more, it can support the stress of the radial direction at the time of winding of a polymer film, Therefore It can prevent that a knurling gets loose. Therefore, deformation of the film roll can be suppressed.

  In this case, it is preferable that the height of the convex portion having a tip curvature radius of 1 μm or more and 3 μm or less is lower than the height of the projection portion having a tip curvature radius of 5 μm or more.

  The height of the gentle convex part with a tip curvature radius of 5 μm or more is higher than the sharp convex part with a tip curvature radius of 1 μm or more and 3 μm or less, so that the polymer film can be wound with a gentle convex part with a tip curvature radius of 5 μm or more. Since the radial stress at the time of taking is supported, it is possible to prevent a sharp convex portion having a curvature radius of 1 μm or more and 3 μm or less from being crushed.

  According to the polymer film of the present invention, it is possible to provide a polymer film in which knurling capable of preventing the polymer film from slipping and generating scratches at the pass rollers is formed at both ends of the film width.

It is explanatory drawing which shows the outline | summary of a film manufacturing equipment. It is a top view which shows the outline | summary of a knurling provision apparatus. It is the III-III sectional view taken on the line of a knurling provision apparatus. It is an enlarged view of the peripheral surface of a knurling provision roller. It is explanatory drawing which shows a mode that a knurling is provided to a polymer film with a knurling provision roller. It is a top view which shows the outline | summary of the surrounding surface of a knurling provision roller. It is a perspective view which shows the outline | summary of a knurling. It is sectional drawing which shows the outline | summary of a knurling. It is a top view which shows the outline | summary of knurling. It is sectional drawing which shows the outline | summary of the front-end | tip curvature radius of the convex part of a knurling.

  A preferred embodiment of a polymer film in which knurling according to the present invention is formed at both ends of a film width will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, the film manufacturing facility 10 includes a film manufacturing apparatus 12 that manufactures a strip-shaped polymer film 11 and a winding apparatus 14 that forms a film roll 13 formed by winding the polymer film 11.

  The width W of the polymer film 11 is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. The present invention is also effective when the width W of the polymer film 11 is greater than 2500 mm. The thickness of the polymer film 11 is preferably 30 μm or more and 200 μm or less, more preferably 40 μm or more and 150 μm or less, and further preferably 40 μm or more and 100 μm or less. The length of the polymer film 11 is preferably 2000 m or more, and more preferably 4000 m or more and 8000 m or less. Moreover, it is preferable that the diameter (winding radius) of the film roll 13 is 450 mm or more, and it is more preferable that it is 650 mm or more and 920 mm or less.

  In addition, a transport path for the polymer film 11 is provided between the film manufacturing apparatus 12 and the winding apparatus 14. In the transport path of the polymer film 11, the polymer film 11 is transported in the longitudinal direction of the polymer film 11 (hereinafter referred to as “A direction”). In the transport path of the polymer film 11, a knurling application device 15 that applies knurling to both end portions (ear portions) in the width direction of the polymer film 11 is provided.

  The winding device 14 includes a cylindrical winding core 21 that winds the polymer film 11 fed from the knurling device 15. Further, the winding device 14 presses the polymer film 11 fed from the knurling device 15 to the winding core 21 and the polymer film 11 guided by the guide roller 22 in the direction of the winding core 21. And a pressing roller 23.

  As shown in FIGS. 1 and 2, the knurling application device 15 includes a knurling application roller pair 26 that nips the polymer film 11 conveyed in the direction A, and a shift unit 27 that adjusts the pressing force of the knurling application roller pair 26. The knurling roller pair 26 has a heater 28 for adjusting the temperature of the peripheral surface of each roller.

  The knurling roller pairs 26 are respectively disposed on both sides of the polymer film 11 in the width direction (hereinafter referred to as B direction). As shown in FIG. 3, the knurling roller pair 26 includes a cylindrical first roller 31 and a cylindrical second roller 32 that is spaced apart from the first roller 31. The first roller 31 is attached to the first rotation shaft 31x, and the second roller 32 is attached to the second rotation shaft 32x. The first roller 31 faces the second roller 32 through the transport path of the polymer film 11. The first roller 31 is disposed on the first surface 11 h side of the polymer film 11. The second roller 32 is disposed on the second surface 11 t side of the polymer film 11.

  As shown in FIGS. 4 and 5, a plurality of convex knurling teeth 31 b are provided on the peripheral surface 31 a of the first roller 31 at a predetermined pitch. The convex knurling teeth 31b are provided so as to protrude from the peripheral surface 31a and are formed in a quadrangular pyramid shape. The peripheral surface 32a of the second roller 32 is formed flat. In addition, it is preferable that the surrounding surface 32a is smooth.

  As shown in FIG. 6, the convex knurling teeth 31b include side ridges 33ab, 33bc, 33cd, 33da formed by the first side surface 33a to the fourth side surface 33d, and the first side surface 33a to the fourth side surface 33d and the circumferential surface. The peripheral surface side ridges 33ax, 33bx, 33cx, 33dx formed by 31a and the upper surface side ridges 33ay, 33by, 33cy, 33dy formed by the first side surface 33a to the fourth side surface 33d and the upper surface 33y are formed. The

  The angle θ1 of at least one of the four corners formed by the upper surface side edges 33ay to 33dy is greater than 0 ° and equal to or less than 90 °. In addition, the angle θ1 of at least one of the four angles formed by the upper surface side edges 33ay to 33dy is preferably greater than 0 ° and less than 90 °, and more preferably greater than 0 ° and less than or equal to 70 °. preferable. If the angle θ1 of at least one of the angles formed by the upper surface side ridges 33ay to 33dy is greater than 0 ° and 90 ° or less, the other angles may be obtuse. In the drawing, the angle formed by the upper surface side ridges 33ay and 33by is shown as the angle θ1, but the present invention is not limited to this, and the angle formed by the upper surface side ridge 33by and the upper surface side ridge 33cy is the upper surface. The angle θ1 may be either an angle formed by the side ridge 33cy and the upper surface ridge 33dy or an angle formed by the upper surface ridge 33dy and the upper surface ridge 33ay.

In order to form a knurling capable of both preventing winding deviation and winding looseness and preventing ear elongation, the total sum of the lengths of the peripheral surface side ridges 33ax to 33dx formed per 1 cm ^{2 on the} peripheral surface 31a is It is preferably 3 mm or less, and more preferably 2.5 mm or less. The total sum is preferably 0.95 mm or more, and more preferably 1.0 mm or more. Further, the total sum of the lengths of the respective upper surface side ridges 33ay to 33dy formed per 1 cm ^{2 on the} peripheral surface 31a is preferably 0.95 mm or more, and more preferably 1.0 mm or more. The total sum is preferably 3 mm or less, and more preferably 2.5 mm or less. The lengths of the peripheral surface side ridges 33ax to 33dx may be equal to each other or different from each other. The length of each of the peripheral surface side ridges 33ax to 33dx is preferably, for example, not less than 0.25 mm and not more than 0.70 mm. Similarly, the length of each of the upper surface side ridges 33ay to 33dy is preferably 0.25 mm or more and 0.70 mm or less, for example. Further, the number of side ridges 33ab, 33bc, 33cd, 33da is preferably 50 or more and 120 or less per 1 cm ^{2 on the} peripheral surface 31a.

  The convex knurling teeth 31b are not limited to a quadrangular frustum shape, but may be a triangular frustum shape, a pentagonal frustum shape, a hexagonal frustum shape, a frustum shape, or other frustum shapes, or a cylinder or a polygonal shape. It may be a columnar shape such as one or two or more ridges.

  As shown in FIGS. 1 and 2, the shift portion 27 nips the ear portion 11 a of the polymer film 11 using a knurling roller pair 26. The width of the ear portion 11a is preferably 0.001 to 0.01 times the width W of the polymer film 11. Since the first roller 31 and the second roller 32 are adjusted to a predetermined temperature by the heater 28, the ear portion 11a nipped by the knurling roller pair 26 is heated. Furthermore, as shown in FIG. 4, since the convex knurling teeth 31b are provided on the peripheral surface 31a of the first roller 31, the outer shape of the convex knurling teeth 31b is transferred to the ear portion 11a by thermal deformation (see FIG. 5). Thus, the knurling application area 40 is formed in the ear 11a on the first surface 11h side by the knurling application roller pair 26 (see FIG. 2). The knurling application area 40 is a portion of the polymer film 11 that has passed between the first roller 31 and the second roller 32 (see FIG. 3). A plurality of knurlings 41 are arranged in the knurling provision area 40 (see FIG. 4).

  As shown in FIGS. 7 and 8, the knurling 41 has a convex knurling portion 42 and a concave knurling portion 43. The convex knurling portion 42 and the concave knurling portion 43 are formed by pressing the peripheral surface 31a having the convex knurling teeth 31b and the peripheral surface 32a (see FIG. 5). The concave knurling portion 43 is a portion formed so that the protruding end portion of the convex knurling teeth 31b becomes a mold and is recessed from the first surface 11h. The convex knurling part 42 is provided at the periphery of the concave knurling part 43 and is formed to protrude from the first surface 11h. The convex knurling part 42 has a ridge 51 at the protruding end. The convex knurling portion 42 is a part of the polymer film 11 that is pushed out around the convex knurling teeth 31b by the pressing of the convex knurling teeth 31b and the peripheral surface 32a (see FIG. 5).

  As shown in FIG. 9, the convex knurling portion 42 includes four protrusions 42 a to 42 d surrounding the concave knurling portion 43. Edge lines 52a to 52d are formed at the protruding ends of the protrusions 42a to 42d. Intersections 53 of the ridge lines 52a to 52d are formed at the ends of the portions where the protrusions 42a to 42d intersect. Thus, a ridge 51 composed of the ridge lines 52 a to 52 d and the intersection 53 is formed at the protruding end of the convex knurling portion 42. The height H1 (see FIG. 8) of each ridgeline 52a to 52d from the first surface 11h is preferably 3 μm to 30 μm, more preferably 3 μm to 15 μm, and more preferably 3 μm to 9 μm. Particularly preferred.

  As shown in FIGS. 7 and 9, the angle θ2 of at least one of the four corners formed by the ridge lines 52a to 52d is greater than 0 ° and equal to or less than 90 °. If the angle θ2 of at least one of the angles formed by the ridge lines 52a to 52d is greater than 0 ° and 90 ° or less, the other angles may be obtuse. The angle θ2 is preferably greater than 0 ° and less than 90 °. In the figure, the angle θ2 is shown as the angle formed by the ridgeline 52a and the ridgeline 52b. However, the present invention is not limited to this, and the angle formed by the ridgeline 52b and the ridgeline 52c, the ridgeline 52c and the ridgeline 52d, The angle θ2 may be any of the angle formed by the ridgeline 52d and the ridgeline 52a.

  As shown in FIG. 8, the concave knurling part 43 has a recessed part 55. The recessed portion 55 is provided so as to be lower than the first surface 11 h where the knurling 41 is not provided. In FIG. 8, the thickness of the polymer film 11 in the recessed portion 55 is thinner than the thickness of the portion where the knurling 41 is not provided, but the present invention is not limited to this, and the thickness of the polymer film 11 in the recessed portion 55 is The thickness may be equal to the thickness of the portion where the knurling 41 is not provided, or may be thicker than the thickness of the portion where the knurling 41 is not provided. Here, the part where the knurling 41 is not provided refers to a part of the polymer film 11 excluding the knurling provision area 40.

  The convex knurling portion 42 provided on the ear portion 11a prevents slippage and loosening of winding because the polymer film 11 is prevented from slipping when the polymer film 11 is wound up to form a film roll 13. .

  The radius of curvature R of the tip of the convex knurling portion 42 is set to be 1 μm or more and 3 μm or less. By forming a knurling having a tip radius of curvature R of the convex knurling portion 42 of not less than 1 μm and not more than 3 μm at both ends of the film width, the effect of removing air between the polymer film and the pass roller is improved.

  FIG. 10 is a schematic view showing a cross section of the convex knurling portion 42. As shown in FIG. 10, the tip of the convex knurling portion 42 has a radius of curvature. When a knurling having a tip radius of curvature R of the convex knurling portion 42 of 1 μm or more and 3 μm or less is formed at both ends of the film width, the effect of removing air between the polymer film and the pass roller is improved. Therefore, since the polymer film 11 is conveyed without slipping with the pass roller of the film manufacturing facility 10, there is almost no scratch.

  In the present invention, the polymer film 11 is provided with both a convex knurling portion having a tip curvature radius of 1 μm or more and 3 μm or less of the convex knurling portion 42 and a convex knurling portion having a tip curvature radius of the projection knurling portion 42 of 5 μm or more. It is also preferable to impart knurling.

  By forming the knurling with the tip curvature radius of the convex knurling portion being 1 μm or more and 3 μm or less at both ends of the film width, the effect of removing air between the polymer film and the pass roller is improved. Therefore, since the polymer film is conveyed without slipping with the pass roller, there is almost no scratch.

  Moreover, since it has the convex knurling part whose front-end curvature radius of a convex knurling part is 5 micrometers or more, since it can support the stress of the radial direction at the time of winding of a polymer film, it can prevent that knurling gets loose. it can. Therefore, deformation of the film roll can be suppressed.

  In this case, it is preferable that the height of the convex knurling portion having a tip curvature radius of 1 μm or more and 3 μm or less is lower than the height of the convex knurling portion having a tip curvature radius of 5 μm or more.

  The height of the gently convex knurling portion with a tip curvature radius of 5 μm or more is higher than the sharp convex knurling portion with a tip curvature radius of 1 μm or more and 3 μm or less, so that the polymer film is a gentle projection with a tip curvature radius of 5 μm or more. Since the radial stress at the time of winding is supported, it is possible to prevent the sharp convex knurling portion having a curvature radius of 1 μm or more and 3 μm or less from being crushed.

  In order to provide the convex knurling portion with both a sharp convex knurling portion with a tip curvature radius of 1 μm or more and 3 μm or less and a gentle convex knurling portion with a tip curvature radius of 5 μm or more, the knurling imparting device shown in FIGS. This can be achieved by providing two 15 and changing the shape of the convex knurling teeth of the first roller for each knurling applicator, or changing the heating temperature condition of the knurling applicator pair 26 and the nip pressure. Further, the single knurling applicator 15 can also achieve the shape of the convex knurling teeth of the first roller by using a roller in which two types of shapes are mixed.

  When the temperature of the convex knurling teeth is high, the amount of deformation of the base increases, and as a result, a knurling having a high aspect ratio is formed. On the other hand, when the temperature of the convex knurling teeth is low, the amount of deformation of the base is reduced, resulting in gentle knurling. Accordingly, the radius of curvature of the tip increases.

  Thus, by making a difference in temperature between the first knurling applicator and the second knurling applicator, convex knurling portions having different tip curvature radii can be mixed.

  In the above embodiment, the convex knurling portion has a quadrangular frustum shape, but the present invention is not limited to this, and the triangular frustum shape, the pentagonal frustum shape, the hexagonal frustum shape, and the frustum shape Another frustum shape may be sufficient and one or two or more protrusions may be sufficient.

  In addition, the direction which provides each knurling may face any direction. The direction of each knurling may be the same direction or may be random.

(Method for producing polymer film)
In the film manufacturing apparatus 12, a solution film forming method, a melt film forming method, and other film forming methods are performed to produce a polymer film. In the case of a solution casting method, a polymer solution in which a raw material polymer is dissolved in a solvent is flowed to a support to form a liquid film. Thereafter, the liquid film is peeled off, and the solvent is evaporated from the liquid film to obtain a polymer film. In addition, from the viewpoint of workability for peeling off from the support, a self-supporting expression step may be performed before peeling from the support. In the self-supporting expression step, the liquid film may be cooled until the self-supporting property is developed, or the solvent may be evaporated from the liquid film until the self-supporting property is expressed. In the case of the melt film forming method, the melted raw material polymer is extruded into a film using an extruder.

(polymer)
In the said embodiment, the polymer used as the raw material of a polymer film is not specifically limited. When performing the solution casting method, examples of the raw material polymer include cellulose acylate and cyclic polyolefin. On the other hand, when the melt film-forming method is performed, examples of the raw material polymer include cellulose acylate, lactone ring-containing polymer, cyclic polyolefin, and polycarbonate. Among them, cellulose acylate and cyclic polyolefin are preferable, and cellulose acylate containing acetate group and propionate group and cyclic polyolefin obtained by addition polymerization are more preferable, and cyclic polyolefin obtained by addition polymerization is more preferable. It is.

(Use)
The polymer film of the present invention is useful as a polarizing plate protective film or a retardation film. An optically anisotropic layer, an antireflection layer, an antiglare function layer, and the like may be added to the polymer film to form a highly functional film.

  In the film production apparatus 12 shown in FIG. 1, a cellulose acylate film having a length of 5000 m, a width of 1500 mm, and a thickness of 80 μm was produced. Thereafter, the convex portions (convex knurling portions) shown in Examples 1 to 5 and Comparative Examples 1 to 3 in Table 1 below are formed with the knurling applicator 15 having the first roller 31 and the second roller 32. It provided in the part 11a. And the cellulose acylate film by which the knurling 41 was provided to the ear | edge part 11a with the winding device 14 was wound around the winding core 21, and it was set as the film roll 13. FIG.

<Scratch evaluation>
The film after winding was visually observed to confirm the presence or absence of scratches. The case where there was no scratch was evaluated as ◯, the case where there was a very small but no problem in practical use was evaluated as Δ, and the case where there was a scratch having a length of 1 mm or more was evaluated as ×.

<Evaluation of deformation of winding roll over time>
The wound film roll was left for 2 weeks, and the subsequent deformation of the take-up roll was visually evaluated. A film having no deformation was evaluated as ◎, a film having almost no deformation was evaluated as ◯, a product having a slight deformation was evaluated as △, and a film having a large amount of deformation and a deformation mark remained was evaluated as x.

  From Examples 1 and 2 and Comparative Examples 1 to 3 in Table 1, it can be seen that the tip curvature radius R of the convex portion is preferably 1 μm or more and 3 μm or less.

  Further, from Examples 1 to 5 in Table 1, not only a convex portion (convex portion 1) having a tip radius of curvature R of 1 μm to 3 μm but also a convex portion (convex portion 2) having a tip radius of curvature of 5 μm or more was provided. The film has almost no deformation over time of the take-up roll, and has a gentle convex portion (convex portion 2) having a tip curvature radius of 5 μm or more than a sharp convex portion (convex portion 1) having a tip curvature radius of 1 μm or more and 3 μm or less. It can be seen that when the height is high, the winding roll is not deformed with time.

  DESCRIPTION OF SYMBOLS 10 ... Film manufacturing equipment, 11 ... Polymer film, 12 ... Film manufacturing apparatus, 13 ... Film roll, 15 ... Knurling provision apparatus, 17 ... Winding apparatus, 26 ... Knurling provision roller pair, 31 ... First roller, 31b ... Knurling Teeth, 32 ... second roller, 41 ... knurling, 42 ... convex knurling portion (convex portion), 43 ... concave knurling portion, 51 ... ridge, 52 ... ridge line, 53 ... intersection, 55 ... recessed portion

Claims (2)

A knurling is a polymer film formed at both ends of the film width,
The knurling has a convex portion, and has a convex portion whose tip curvature radius is 1 μm or more and 3 μm or less and a convex portion whose tip curvature radius is 5 μm or more. Feature polymer film. The height of the convex portion and the tip curvature radius is 1μm or more 3μm or less, the polymer film of claim 1, wherein the tip radius of curvature is equal to or lower than the height of the convex portion is 5μm or more.

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