JP2011016245A - Stretched polymer film, polarizer film, light scattering film and linearly cuttable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretched polymer film which is obtained by stretching an original polymer film uniaxially only to the lateral direction perpendicular to the conveying direction and which has an excellent molecular orientation property in the lateral direction.SOLUTION: The stretched polymer film is obtained by a method for stretching the long polymer film, which is supplied continuously and conveyed while being held by both ends thereof, to the lateral direction perpendicular to the conveying direction. The method for stretching the polymer film includes: a loosening step of loosening both ends of the polymer film by a member having a rugged shape; a holding step for holding both ends of the polymer film in a loosened state, on a conveyance unit; and a stretching step of stretching the resulting polymer film to the lateral direction by widening the polymer film to the lateral direction perpendicular to the conveying direction while the polymer film is conveyed by the conveyance unit.

Description

  The present invention relates to a stretched polymer film, a polarizer film, a light scattering film, and a linear cutting film. More specifically, the present invention is uniaxially stretched only in the transverse direction with respect to the transport direction and has excellent molecular orientation in the transverse direction. The present invention relates to a stretched polymer film, a polarizer film comprising the stretched polymer film, a light scattering film, and a linear cutting film.

  For example, as described in Patent Document 1, a film stretching machine is known that stretches a film in the width direction by widening the distance between the clips on both sides while gripping and transporting both sides of the film with clips. .

  In the film stretching machine disclosed in Patent Document 1, the conventional clip for gripping the film has a flapper that swings so that the tip can come into contact with the film mounting surface, and the tension of the film mounts the flapper. The contact angle of the flapper with respect to the placement surface is set so as to act in the direction of pressing against the placement surface.

  Here, generally, the gripping portion of the flapper is formed in a flat surface so that the film can be gripped in a flat shape.

JP 2005-104081 A JP-A-4-230704 JP-A-5-11111 JP-A-5-11114 Japanese Patent Laid-Open No. 5-288931 Japanese Patent Laid-Open No. 5-288932

  When stretching the film in a direction transverse to the transport direction, as described in Patent Document 1, while holding and transporting both sides of the film with clips, A film stretching machine for stretching a film in the width direction is known. In some cases, a tenter pin is used instead of the clip.

  The conventional clip for gripping the film has a flapper that swings so that the tip can come into contact with the film mounting surface, and the flapper acts so that the tension of the film acts in the direction of pressing the flapper against the gripping portion. The contact angle of the grip portion is set. Generally, the gripping portion of the flapper is formed in a flat surface so that the film can be gripped in a flat shape.

  The film is subjected to stress to change the molecular arrangement and impart polarization characteristics and the like. The purpose of the stretching technique is to obtain desired optical characteristics by controlling this. However, when the film is simply stretched in the transverse direction with respect to the transport direction, it tends to shrink in the transport direction, so that a tensile stress acts also in the transport direction on the film whose both ends are fixed by clips or the like. When such stress in the transport direction acts, the film will be stretched in the longitudinal direction at the same time as stretching in the lateral direction, and uniaxial stretching only in the lateral direction cannot be realized, giving the film undesirable properties. Result.

  Further, when stretching in the lateral direction, a phenomenon called so-called bowing occurs, and there is a problem in that the orientation direction of the molecules becomes uneven in the lateral direction.

  Techniques for solving such problems are disclosed in, for example, Patent Documents 2, 3, 4, and 5. The techniques disclosed in Patent Documents 2, 3, 4, and 5 are methods for relaxing stretching in the longitudinal direction by utilizing thermal shrinkage of the film after obtaining a film stretched in the longitudinal direction in the transverse stretching step. It is. However, this method requires two steps, a transverse stretching step and a relaxation step, and has a problem that efficiency is poor.

  Patent Document 6 discloses a technique of stretching in the lateral direction while maintaining a state where both end portions of the film are shaped into a waveform. With this method, uniaxial stretching only in the transverse direction can be achieved, and the bowing phenomenon in the transverse direction can be reduced. However, Patent Document 6 does not describe a method for forming a waveform or a stretching method. In particular, means for continuously performing a stretching process or a film, which is most important for film production, is continuously applied to a waveform. No means for forming was disclosed, and it was poor in practicality.

  In view of the above-mentioned present situation, an object of the present invention is to provide a stretched polymer film that is uniaxially stretched only in the transverse direction with respect to the transport direction and has excellent molecular orientation in the transverse direction.

  The present invention for solving the above-described problems is as follows.

1. It is a polymer stretched film obtained by a method of transporting while holding both ends of a long polymer film that is continuously supplied, and stretching the polymer film in a direction transverse to the transport direction while transporting the polymer film. ,
The method
A step of loosening both ends of the polymer film by a member provided with an uneven shape;
A holding step of holding both ends of the loose polymer film in the transport device;
A stretching step of stretching the polymer film in the transverse direction by widening in the transverse direction with respect to the transport direction while transporting the polymer film by the transport device;
A polymer stretched film characterized by comprising:

2. In the method, the polymer film is held in the transverse direction by holding the end of the polymer film with a holding member piece having a concavo-convex holding member piece in a state in which a partial region or the entire region of the polymer film is slackened in the transport direction. 2. The stretched polymer film according to 1, which is a starting material.

3. The method is to start stretching in a transverse direction in a state where a partial region or the entire region of the polymer film is loosened by alternately pressing one surface and the other surface of the polymer film. 3. The stretched polymer film as described in 1 or 2 above.

4). The polarizer film which consists of a polymer stretched film in any one of said 1-3.

5. The light-scattering film which consists of a polymer stretched film in any one of said 1-3.

6). The linear cutting film which consists of a polymer stretched film in any one of said 1-3.

  Since the polymer stretched film of the present invention is selectively stretched only in the transverse direction and uniformly stretched at each position in the transverse direction, it is extremely excellent in molecular orientation in the transverse direction. Therefore, it is suitably used as a polarizer film, a light scattering film, a linear cutting film and the like.

  The polarizer film of the present invention is wide and has a high degree of polarization.

  The light scattering film of the present invention is wide and light scattering is uniform over the entire surface.

  The linear cutting film of the present invention is wide and has a uniform linear cutting property on the entire surface.

(A) is a side view of the clip in the first embodiment (the broken line is a wave-like gripping member), and (b) is an explanatory view (b) showing the relationship between the clip and the film. (A) is a side view of a clip in the second embodiment (broken lines are wavy gripping members), and (b) is an explanatory view (b) showing the relationship between the clip and the film. It is a top view which shows an example of the film extending machine which can be used for manufacture of the polymer stretched film of this invention. It is a front view of a clip and a wavelike holding member. FIG. 4 is a side view of the feeder chain and the wavy gripping member of FIG. 3. FIG. 4 is a partially enlarged side view of the feeder chain and the wavy gripping member of FIG. 3. It is a perspective view of the film extending machine of FIG. It is a cross-sectional perspective view of the film stretching machine in the state holding the film. It is a perspective view of the clip in a first embodiment. (A) is a front view of the clip immediately before holding the film in 1st embodiment, (b) is a side view of the clip just before holding the film in 1st embodiment. (A) is a front view of the clip in the state which hold | maintained the film in 1st embodiment, (b) is a side view of the clip in the state which hold | maintained the film in 1st embodiment. It is a perspective view of a wavy holding member. It is explanatory drawing which shows the relationship between the position of the polymer film in 1st embodiment, and the attitude | position of a clip and a wavy holding member. It is a perspective view of the clip in 2nd embodiment. (A) is a front view of the clip just before holding the polymer film in 2nd embodiment, (b) is a side view of the clip just before holding the polymer film in 2nd embodiment. (A) is a front view of the clip in the state which hold | maintained the polymer film in 2nd embodiment, (b) is a side view of the clip in the state which hold | maintained the polymer film in 2nd embodiment. It is explanatory drawing which shows the relationship between the position of the polymer film in 2nd embodiment, and the attitude | position of a clip and a wave-shaped holding member. It is sectional drawing which shows the behavior of the polymer film at the time of hold | maintaining a polymer film with the clip in 1st embodiment. It is sectional drawing which shows the behavior of the polymer film at the time of hold | maintaining a polymer film with the clip in 2nd embodiment. It is a front view which shows the modification of the member provided with the uneven | corrugated shape. It is a perspective view which shows the other modification of the member provided with the uneven | corrugated shape. It is a side view which shows the modification of a feeder chain and a wave-shaped holding member. It is a conceptual diagram which shows the modification of the method of making a polymer film wave. It is a conceptual diagram which shows the other modification of the method of making a polymer film wave. It is a conceptual diagram which shows the further another modification of the method of making a polymer film wave.

  One aspect of the present invention is obtained by a method of transporting while holding both ends of a long polymer film that is continuously supplied, and stretching in a direction transverse to the transport direction while transporting the polymer film. The method includes a step of loosening both ends of the polymer film by a member provided with an uneven shape, and holding the both ends of the loose polymer film in a transport device A process and a stretching process of stretching the polymer film in the transverse direction by widening the film in the transverse direction with respect to the transport direction while transporting the polymer film by the transport device.

  In the above method, the polymer film that is continuously supplied is preliminarily slackened (preferably after being shaped into a waveform) and then held on the conveying device while maintaining a slackened state (preferably a waveform). It becomes possible, and it becomes possible to stretch | stretch the polymer film shape | molded by the waveform continuously and smoothly to a horizontal direction. By performing such stretching, it is possible to prevent the film from being stretched in the transport direction simultaneously with stretching in the transverse direction, and to produce a film that is selectively stretched only in the transverse direction.

  Here, the state of “loosening” refers to a state in which the actual length of the polymer film existing at a specific interval in the transport state is longer than the specific interval described above. It can be said that the polymer film is excessively supplied. When the shape in the “loosening” state is appearance, for example, a wavy state can be considered. The “wavy state” may be a state in which the shape and period of the peaks and valleys are irregular, but for the purpose of uniform quality, it is desirable that the shape and period of the peaks and valleys be regular. . As a recommended form of "sagging" state, in addition to the state where peaks and valleys like sine curves exist regularly, only the state where valleys exist and valleys like pulsation only The state which exists is mentioned. Further, it may be in the form of fine vibration.

  Further, “shaping into a waveform” means to make a wave shape (that is, not a flat shape) without plastic deformation.

  In a preferred embodiment, the method comprises holding the end of the polymer film with a holding member provided with a holding member piece having a concavo-convex shape in a state where a partial region or the entire region of the polymer film is slackened in the transport direction. The stretching in the transverse direction is started.

  In a preferred embodiment, the method starts lateral stretching in a state where a partial region or the entire region of the polymer film is loosened by alternately pressing one surface and the other surface of the polymer film. Is.

  As the raw material resin for the polymer film employed in the present invention, an appropriate one is appropriately selected according to the purpose. Specific examples include polycarbonate resins, norbornene resins, polyolefin resins, cellulose resins, urethane resins, styrene resins, polyvinyl chloride resins, acrylonitrile / styrene resins, polymethyl methacrylate, polyvinyl acetate, Polyvinylidene chloride resin, acrylonitrile / butadiene / styrene resin, polyamide resin, polyacetal resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene resin, polypropylene resin, nylon resin , Polyvinyl alcohol resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyarylate resin, liquid RESIN, polyamideimide resins, polyimide resins, polytetrafluoroethylene resins. In particular, polycarbonate resins, norbornene resins, polyolefin resins, cellulose resins, urethane resins, styrene resins, polyimide resins, and polyamide resins are preferable because they have good optical properties and strength when formed into a film. .

  Said raw material resin is used individually or in combination of 2 or more types. Moreover, said raw material resin can also be used after performing arbitrary appropriate polymer modification | denaturation. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity.

  The polymer film employed in the present invention can be molded and obtained by various methods. For example, it is obtained by a casting method in which a resin is dissolved in an organic solvent and cast on a support, and the solvent is dried by heating to form a film, or a melt extrusion method in which the resin is melted and extruded from a T-die to form a film. be able to. Further, it is possible to adopt a laminated film in which a thin film layer is further formed on one side or both sides of a molded polymer film by a gravure coater or the like.

  The polymer film can contain other components such as a plasticizer, a stabilizer, a residual solvent, an antistatic agent, and an ultraviolet absorber as necessary, as long as the object of the present invention is not impaired. Further, a leveling agent can be added to reduce the surface roughness. Those having good compatibility with the resin are preferable.

  The thickness range of the polymer film can be selected according to the designed retardation value, stretchability, retardation development property, etc., but those having a thickness of 10 to 500 μm are preferably used. More preferably, it is 10-200 micrometers. If it is said range, sufficient self-supporting property of a film will be obtained and a wide range of workability can be obtained.

  Next, a method for producing the polymer stretched film of the present invention and an example of an apparatus for production will be described in detail below with reference to the drawings. However, the present invention is not limited to these.

  The polymer stretched film of the present invention is stretched in the transverse direction with respect to the transport direction in a state where the polymer film F is shaped into a waveform by holding the polymer film F with the holding members 2 and 55 having a specific shape. Can be manufactured. This method is based on the basic idea that the polymer film F can prevent stretching in the transport direction while being stretched in the transverse direction, and can produce the polymer film F selectively stretched only in the transverse direction. To do.

  Furthermore, another important point of the present method is that in order to realize the stretching operation continuously and smoothly, the supply process of the polymer film F, the polymer film F is continuously shaped into a waveform along the transport direction. There is a step of continuously carrying out a step of gripping both ends of the film F shaped into a waveform with a transport device and a step of stretching the polymer film F in the lateral direction while transporting the polymer film F.

  In this method, as a preferable aspect of the holding member 2 for stretching the polymer film F in a wave shape, the upper teeth and lower teeth of the holding member 2 are engaged with each other. A clip with an uneven shape can be mentioned. If the clip having such a structure is used, the polymer film F can be shaped into a corrugated shape, and the polymer film F can be stretched transversely with respect to the transport direction while maintaining the state. It becomes possible. The period and size of the shape of the irregularities that bite the polymer film F are arbitrarily selected according to the physical properties of the polymer film F and the draw ratio.

An example (first embodiment) of the clip-type holding member 2 is shown in FIG. The surface of the holding member 2 sandwiching the film F is composed of an upper tooth portion (holding member piece) 12 and a lower tooth portion (holding member piece) 11 that are corrugated with each other. Since the polymer film F gripped by such a clip forms a corrugated shape, the object of the present method can be achieved.
As another preferred embodiment of the holding member for stretching the polymer film F in a wave shape in a direction transverse to the conveying direction, a holding member piece like a holding member 55 as shown in FIG. A clip having a structure in which one of 56 and 57 has an uneven shape and the other has a planar shape (second embodiment). The clip having such a structure is preferable because the polymer film F can be stretched by shaping it into a waveform having an arbitrary height or period. Furthermore, when using a device that continuously shapes the polymer film F into a waveform, such as the above-mentioned film overfeed device, the waveform period and height of the shaped polymer film F are not constant. In addition, the end portion of the polymer film F can be securely sandwiched, which is the most preferred embodiment.

  The upper surface of the surface of the holding member 55 sandwiching the polymer film F is an upper tooth portion (holding member piece) 56 having a corrugated uneven shape. On the other hand, the lower surface is a flat surface 57. When such a clip is used to hold a polymer film F that is shaped into a corrugated shape using a film overfeed device, which will be described later, the polymer film F can be stretched in the lateral direction while maintaining the corrugated shape. .

  Next, the outline | summary is demonstrated about the film stretcher 1 which can be used for manufacture of the polymer stretched film of this invention.

  As shown in FIG. 3, the film stretching machine 1 includes a tenter chain 3 in which clips 2 for holding both ends of the polymer film F are provided at equal intervals, and a polymer film F held by the tenter chain 3 with hot air. A heating furnace 4 that heats the polymer film F, and the polymer film F is stretched in the width direction by widening the interval between the tenter chains 3 that hold the polymer film F. In addition, the film stretching machine 1 includes two pairs of front and back surfaces of the polymer film F, each of which circulates in a plane parallel to the transport direction of the polymer film F and perpendicular to the transport surface (horizontal plane) of the polymer film F The film overfeed device 7 includes a feeder chain (endless member) 5 and wavy gripping members 6 a and 6 b that are held in the feeder chain 5 at equal intervals to the clip 2 and sandwich the film F from the front and back.

The apparatus for continuously shaping the polymer film F used in the present invention into a waveform along the conveying direction is particularly a structure as long as the apparatus can continuously shape the polymer film F into a waveform. It is not limited. For example, the film overfeed device 7 as shown in FIG. 3 is preferable because it does not give excessive friction and tension to the polymer film F, and can smoothly shape the waveform.
The figure which looked at the film overfeed apparatus 7 from the side in FIG. 5 is shown. In this film overfeed device 7, a wavy gripping member (front-side gripping piece and backside) that is disposed opposite to both front and back surfaces of the polymer film F and sandwiches the polymer film F while moving in the transport direction of the polymer film F. The wavy gripping member 6 is provided with supercharging protrusions 15 that are arranged in the transport direction of the polymer film F and protrude from each other.

  The wavy gripping members (front side gripping pieces and back side gripping pieces) 6a and 6b of the film overfeed device 7 are fixed to the frames of the upper and lower feeder chains 5 at equal intervals. 5 and 6, the wavy gripping members (front gripping pieces and back gripping pieces) 6a and 6b have the lower teeth 11 and upper teeth 12 of the clip 2 in the transport direction of the polymer film F. Supercharging projections 15 projecting toward the film F so as to extend in the width direction (perpendicular to the conveying direction) of the polymer film F are formed alternately at the same pitch as the waveform period. The wavy gripping members (front side gripping pieces and back side gripping pieces) 6a and 6b are engaged with each other when the upper and lower feeder chains 5 are brought close to each other by the feeder guides 16 and 17.

However, the corrugated gripping members (front gripping pieces and back gripping pieces) 6a and 6b do not come into contact with each other even when reapproaching so as to receive the supercharging protrusions 15, and are sufficiently larger than the thickness of the polymer film F. Bite to leave a large gap. Thus, excessive compressive stress is applied to the central portion of the polymer film F so as not to be damaged.
In addition, the supercharging protrusion 15 loosens the whole area of a film in a longitudinal direction beforehand by pressing the surface of the polymer film F at intervals in the transport direction.
Further, in the film overfeed device 7 used in the present invention, the wavy gripping members (the front side gripping pieces and the back side gripping pieces) 6a and 6b are annular rings that circulate in a plane orthogonal to the transport surface of the polymer film F. A plurality of endless members may be held at equal intervals.
The height, width, shape, period, and speed at which the upper and lower supercharging protrusions 15 approach each other are the lengths necessary for contracting the polymer film F. It is possible to freely select from a minimum bending radius or the like for avoiding breakage of the polymer film F.

In the film stretching machine 1 configured as described above, before the clip 2 grips the polymer film F, first, the wavy gripping members 6a and 6b of the film overfeed device 7 gradually sandwich the polymer film F from the upper and lower surfaces. Go on. That is, the supercharging protrusion 15 gradually presses the surface of the polymer film F.
The clip 2 is configured to hold both side ends of the polymer film F with the holding member 2 while the film overfeed device 7 approaches the wave-like holding members 6 a and 6 b to sandwich the polymer film F. .

  The position of sandwiching the polymer film F from above and below with the wavy gripping member 6 is arbitrary, but it is necessary to sandwich the polymer film F inside the end of the polymer film F. That is, it is because it is necessary to hold | maintain the edge part of the corrugated polymer film F to a conveying apparatus, maintaining the waveform of the polymer film F. FIG. As a specific position for sandwiching the polymer film F, it is preferable that the inside of the polymer film F is sandwiched by 5 mm or more from both ends because it interferes with the holding member (clip) 2 or the like if it is too close to both ends. From the viewpoint of securely fixing the molecular film F to the clip 2, it is more preferable to sandwich the inner side by 10 mm or more from both ends. On the other hand, if the position where the polymer film F is sandwiched from above and below is too far from both ends of the film, the waveform of the portion sandwiched between the holding members (clips) 2 will weaken and the polymer film F will be wasted. The position is preferably within 20 mm from the part.

As the apparatus for stretching the polymer film F in the lateral direction while conveying it, a conventional stretching apparatus can be used without any particular limitation. Two sets of chains are passed through a tenter furnace (heating furnace 4), and a device for fixing both ends of the polymer film F is attached to the chain, and the distance between the two sets of chains increases as the chain moves. Is generally suitable for the present invention.
Conditions such as the temperature of the tenter furnace, the stretching ratio of the polymer film F, and the stretching step are arbitrary, and an optimum value can be selected according to the physical properties of the polymer film F.
Any type of polymer film F can be used. A thermoplastic resin is preferable because it can be easily stretched by heating. Specifically, cellulose resin, vinyl chloride resin, polycarbonate resin, acrylonitrile resin, styrene resin, olefin resin, polysulfone resin, cycloolefin resin, norbornene resin, and the like are preferable.

Next, a specific structure of the film stretching machine 1 will be described.
As shown in FIGS. 3 and 7, the film stretching machine 1 includes a film stretching unit 20, a heating furnace 4, and a film overfeed device 7.
The film stretching section 20 includes two systems of tenter chains 3a and 3b, and clips 2 that hold both side ends of the film F are provided at equal intervals on the tenter chains 3a and 3b.
The tenter chains 3a and 3b are suspended from the drive side sprockets 21a and 21b and the driven side sprockets 22a and 22b.
The four sprockets 21a, 21b, 22a, 22b that suspend the tenter chains 3a, 3b are all arranged in the same plane as shown in FIGS. 3 and 7, the four sprockets 21a, 21b, 22a, and 22b that suspend the tenter chains 3a and 3b all have a rotation axis in the direction perpendicular to the paper surface, and the four sprockets 21a , 21b, 22a, 22b are all arranged on a plane parallel to the paper surface.

  As shown in FIGS. 3 and 7, the two tenter chains 3 a and 3 b are arranged so that one running surface faces each other. The opposing running surfaces of the two systems of tenta chains 3 a and 3 b function as the extending action portion 27.

The opposite running surfaces (extension acting portions 27) of the two systems of tenta chains 3a and 3b are constituted by an introduction-side straight portion 23, an inclined portion 24, and a terminal-side straight portion 25.
The running surfaces of the tenter chains 3a and 3b (the extending action portion 27) are such that the introduction-side straight portion 23 and the distal-side straight portion 25 are opposed to the introduction-side straight portion 23 and the distal-side straight portion 25 of the opposing tenta chains 3a and 3b. Parallel. Further, a tapered portion is formed by the inclined portion 24 of the opposing tenta chains 3a and 3b.

Clips (holding members) 2 are provided at equal intervals on the tenter chains 3a and 3b, and both ends of the film F are gripped by the clips 2.
The shape of the clip 2 will be described later.

  The heating furnace 4 heats the film F held by the tenter chains 3a and 3b with hot air.

Next, the film overfeed device 7 will be described.
The film overfeed device 7 includes two pairs (four systems) of feeder chains 5a, 5b, 5c, and 5d.
As shown in FIG. 7, the feeder chains 5a, 5b, 5c, and 5d are a pair of feeder chains 5a and 5b, and the feeder chains 5c and 5d form another pair.
The four sprockets 30, 31, 32, 33 for suspending the pair of feeder chains 5a, 5b are all arranged in the same plane as shown in FIGS. However, the plane formed by the four sprockets 30, 31, 32, 33 is a plane orthogonal to the plane formed by the four sprockets 21a, 21b, 22a, 22b that suspend the tenter chains 3a, 3b. is there.

  Of the four sprockets 30, 31, 32, 33, the sprockets 30, 32 are drive side sprockets, and the sprockets 31, 33 are driven side sprockets.

The other pair of feeder chains 5c and 5d is arranged in parallel with the aforementioned feeder chains 5a and 5b.
Further, the sprockets 30, 31, 32, 33 included in one pair and the sprockets 30 ', 31', 32 ', 33' included in the other pair have shafts 36, 37, 38 that have the same corresponding sprockets. , 39. Accordingly, the sprockets 30, 31, 32, 33 rotate synchronously, and the feeder chains 5c, 5d also run synchronously.

Among the two pairs (four systems) of feeder chains 5a, 5b, 5c, 5d, a plurality of front side gripping pieces 6a are attached to the upper feeder chains 5a, 5c with reference to FIG. On the other hand, a plurality of back side gripping pieces 6b are attached at equal intervals to the lower feeder chains 5b and 5d with reference to FIG.
A front gripping piece 6a attached to the upper feeder chains 5a and 5c and a back gripping piece 6b attached to the lower feeder chains 5b and 5d constitute a pair of wavy gripping members 6. The shapes of the front gripping piece 6a and the back gripping piece 6b will be described later.

The two pairs (four systems) of feeder chains 5a, 5b, 5c, and 5d described above are all in a region that is substantially surrounded by the tenter chains 3a and 3b of the film extending portion 20.
However, the length of the feeder chains 5 a, 5 b, 5 c, 5 d of the film overfeed device 7 (the distance between the sprocket axes) is shorter than the tenter chains 3 a, 3 b of the film extending portion 20.
Therefore, the starting ends of the feeder chains 5a, 5b, 5c, 5d of the film overfeed device 7 are slightly upstream from the starting ends of the tenter chains 3a, 3b of the film stretching section 20, and the feeder chains 5a, 5b, The end portions 5c and 5d are located at the end portion of the introduction-side straight portion 23.

  The feeder chains 5a, 5b, 5c and 5d of the film overfeed device 7 and the tenter chains 3a and 3b run synchronously.

  The heating furnace 4 is provided at the position of the inclined portion 24 of the tenter chains 3 a and 3 b in the film stretching portion 20.

  Next, the clip (holding member) 2 attached to the tenter chains 3a and 3b will be described.

The clip 2 is attached to the tenter chain 3 via the base 8 as shown in FIGS. That is, the base 8 is fixed to the pin of the tenter chain 3 by known means, and the clip 2 is placed on the base 8.
As shown in FIGS. 4, 9, 10, and 11, the clip 2 has a frame 9 having a substantially U-shape that is open to the polymer film F side, and a flapper 10 is attached to the frame 9. .
That is, the frame 9 has a U shape having an upper side 40, a vertical side 41, and a lower side 42. The upper surface (inner surface) of the lower side 42 of the frame 9 functions as the film mounting surface 45, and has a waveform (lower tooth portion 11) in this embodiment. That is, the film mounting surface 45 as a holding member piece is corrugated and has both a convex portion and a concave portion. In addition, it can be said that the film mounting surface 45 has convex portions provided at a constant interval.

Further, the flapper 10 has a flange portion 46 and a pressing portion 47, and an intermediate portion of the flange portion 46 is fixed to the upper side 40 of the frame 9, and the flapper 10 swings like a pendulum. The swinging direction of the flapper 10 is the width direction of the film F. That is, the pressing portion 47 of the flapper 10 moves along an arc locus. Therefore, as shown in FIG. 10, when the flange portion 46 is in an oblique posture, the pressing portion 47 is separated from the film placement surface 45. On the other hand, when the collar portion 46 is in the hanging posture, the lower surface of the pressing portion 47 approaches the film placement surface 45 and presses the film placement surface 45.
Here, in the flapper 10 of this embodiment, the lower surface of the pressing portion 47 has a waveform (upper tooth portion 12). That is, the pressing portion 47 as the holding member piece is also corrugated and has both a convex portion and a concave portion. It can also be said that the pressing portion 47 is also provided with convex portions with a certain interval.
When the flange 46 is in the hanging position, the corrugated shape of the lower surface of the pressing portion 47 (upper tooth portion 12) matches the corrugated shape of the film placement surface 45 (lower tooth portion 11).

As described above, in the flapper 10, since the intermediate portion of the flange portion 46 is fixed to the upper side of the frame 9, the upper end of the flange portion 46 protrudes above the upper side 40 of the frame 9.
Therefore, the flapper 10 can be swung by pressing the upper end of the flange portion 46 in the lateral direction, and the pressing portion 47 of the flapper 10 can be moved close to and away from the film mounting surface 45 as described above.
In this embodiment, a long clip guide 14 is provided in the vicinity of the tenter chains 3a and 3b, and the upper end of the collar portion is brought into contact with the clip guide 14. The positional relationship between the clip guide 14 and the frame 9 is designed to change from place to place, and the flap guide 10 is swung by pressing the upper end of the flange 46 with the clip guide 14.

  FIG. 4 shows details of the clip 2 holding the polymer film F and the wavy gripping member 6. The clip 2 is fixed to a base 8 attached to the frame of the tenter chain 3 at equal intervals, and can be swung to the top end of the frame 9 having a generally U-shaped frame 9 opened to the polymer film F side. And a flapper 10 pivotally supported by the motor. The flapper 10 is provided with an upper tooth portion 12 that engages with a lower tooth portion 11 provided at the lower end of the lower side of the frame 9 at the front end. Further, the flapper 10 swings while an arm portion 13 extending above the frame is guided by a clip guide 14. The clip 2 grips or releases the side edge of the polymer film F with the lower tooth portion 11 and the upper tooth portion 12 by the swing of the flapper 10.

  As shown in FIG. 9, the lower teeth portion 11 and the upper teeth portion 12 of the clip 2 are engaged with a waveform that periodically rises and falls at a predetermined pitch in the transport direction of the polymer film F.

Next, the front side gripping piece 6a and the back side gripping piece 6b attached to the feeder chains 5a, 5b, 5c, and 5d will be described.
As described above, the four feeder chains 5a, 5b, 5c, and 5d are arranged in two pairs, and the pair of feeder chains (5a, 5b) and (5c, 5d) are arranged one above the other. ing. FIG. 5 shows a pair of feeder chains 5a and 5b. FIG. 6 is an enlarged view of a part of FIG. 5 and shows a wave-like gripping member 6 constituted by a front-side gripping piece 6a and a back-side gripping piece 6b.
In the present embodiment, as shown in FIG. 5, the opposite running surfaces of the feeder chains 5 a and 5 b (or 5 c and 5 d) function as the feed operation unit 50.
In the present embodiment, the feeder guide 16 is provided in the travel path on the feed operation unit 50 side, which is an area surrounded by the feeder chain 5a located on the upper side. The feeder guide 16 has a length over substantially the entire traveling path on the feed operation unit 50 side. And the feeder guide 16 becomes a shape which protrudes the intermediate part of a driving | running | working path outside (it is a lower side on the basis of a figure). More specifically, the feeder guide 16 has a gently inclined guide surface, and the vicinity of the end of the travel path projects outward.

  Similarly, a feeder guide 17 is provided for the feeder chain 5b located in the lower part. The feeder guide 17 has a guide surface that is gently inclined, and the vicinity of the end of the traveling path projects outward.

In this embodiment, the front gripping piece 6a is attached to the upper feeder chain 5a, and the back gripping piece 6b is attached to the lower feeder chain 5b.
The front gripping piece 6a provided in the feeder chain 5a has three supercharging projections 15 formed on the lower surface as shown in FIG.
The supercharging protrusion 15 protrudes toward the polymer film F side, has a rib shape, and has a length at the peak. That is, one supercharging protrusion 15 extends over the entire width of the front side gripping piece 6a. The direction of the peak of the supercharging protrusion 15 is along the width direction of the polymer film F.
A portion where the supercharging protrusion 15 does not exist, that is, a valley portion of the supercharging protrusion 15 is flat. The width W of the supercharging protrusion 15 is smaller than the interval w between the supercharging protrusions 15.
It can be said that the front-side gripping piece 6a is provided with the supercharging protrusions 15 with a certain interval. In the present embodiment, the interval between the supercharging protrusions 15 is constant as a recommended configuration, but the interval between the supercharging protrusions 15 may be irregular. The same applies to the back side gripping piece 6b described later.
Note that the lower surface of the front-side gripping piece 6a may be a corrugated surface like a sine curve.
In the present embodiment, a plurality of front side gripping pieces 6a are provided at equal intervals in the upper feeder chain 5a. From this point as well, it can be said that the supercharging protrusions 15 are provided at regular intervals.
The distance between the front gripping pieces 6a is equal to the distance between the clips 2 described above.

A supercharging protrusion 15 is also provided on the back side gripping piece 6b provided in the lower feeder chain 5b.
It can be said that the supercharging protrusion 15 is also provided with a fixed interval also about the back side holding piece 6b.
The shape and interval of the supercharging protrusion 15 provided on the lower back side gripping piece 6b are the same as those of the front side gripping piece 6a described above. However, the front side gripping piece 6a described above has three supercharging protrusions 15, whereas the lower backside gripping piece 6b has four supercharging protrusions 15.
In the present embodiment, a plurality of back side gripping pieces 6b are provided at equal intervals on the lower feeder chain 5b.
From this point as well, it can be said that the supercharging protrusions 15 are provided at regular intervals.
The interval between the back-side gripping pieces 6b is equal to that of the front-side gripping piece 6a.

The feeder chain 5a located on the upper side and the feeder chain 5b located on the lower side run synchronously, and on the running surface (feed action part) 50 where both face each other, the shafts of the front side gripping piece 6a and the back side gripping piece 6b The hearts always match.
However, as described above, feeder guides 16 and 17 are provided in the feeder chains 5a and 5b, respectively, and the running trajectories of the feeder chains 5a and 5b swell outward in the center. The relative distance from the gripping piece 6b varies depending on the travel position of the feeder chains 5a and 5b.
That is, since the feeder guides 16 and 17 both project the end portions of the feed action portions 50 of the feeder chains 5a and 5b to the outside, the front side gripping pieces 6a and the back side are provided at the end portions of the feed action portions 50 of the feeder chains 5a and 5b. When the gripping piece 6b moves, the distance between the two becomes closest (FIG. 13C row).
On the other hand, at the starting end portion of the feed operating unit 50, the front side gripping piece 6a and the back side gripping piece 6b are open as shown in the A row of FIG. 8 and the A row of FIG.

  Therefore, when the feeder chains 5a and 5b travel and the front side gripping piece 6a and the back side gripping piece 6b circulate and reach the feed operation part 50 (opposing travel surface) side, the front side gripping piece 6a and the back side gripping piece 6b face each other. Thus, thereafter, the front side gripping piece 6a and the back side gripping piece 6b travel through the feed operating portion 50 in the facing posture.

At the starting end of the feed operation unit 50, a gap between the front side gripping piece 6a and the back side gripping piece 6b is greatly opened as shown in the row A of FIG.
Specifically, the peak of the front side gripping piece 6a and the peak of the back side gripping piece 6b are separated from each other in the vertical direction as shown in row A of FIG. As the feed action unit 50 travels, the distance between the two becomes narrower as shown in row B of FIG. 13, and the peaks of the front gripping piece 6a and the peaks of the back gripping piece 6b bite.

Then, as the feed action unit 50 travels, the distance between the two becomes closer, and the front gripping piece 6a and the back gripping piece 6b press the surface of the polymer film F. Here, the front gripping piece 6a and the back gripping piece 6b have supercharging protrusions 15 at alternate positions. For example, the tip of the supercharging protrusion 15 on the front gripping piece 6a side shows the surface of the polymer film F below the drawing. The reaction force at the time of pressing to the side is held by the supercharging protrusion 15 of the back side gripping piece 6b at the opposite position.
Therefore, the polymer film F is shaped into a corrugated shape only at the portion sandwiched between the wave-like gripping members 6 without moving up and down as a whole.
As described above, both the front-side gripping piece 6a and the back-side gripping piece 6b can be said to have the supercharging projections 15 provided at a constant interval, so the front and back surfaces of the polymer film F are spaced in the transport direction. It can also be considered that it is pressed with a gap, and as a result, only the portion sandwiched between the wavy gripping members 6 is loosened and shaped into a waveform.

  Further, since the front side gripping piece 6a and the back side gripping piece 6b gradually approach each other as the feeder chains 5a and 5b run, the polymer film F is gradually sandwiched between the front side gripping piece 6a and the back side gripping piece 6b. It becomes.

When the front side gripping piece 6a and the back side gripping piece 6b reach the vicinity of the terminal portion of the feed operation unit 50, the front side gripping piece 6a and the back side gripping piece 6b are closest to each other.
When the front-side gripping piece 6a and the back-side gripping piece 6b reach the vicinity of the terminal end of the feed operating portion 50, the front-side gripping piece 6a and the back-side gripping piece 6b are engaged with each other as shown in the C and C rows of FIG. Although it becomes an attitude | position, the front side holding piece 6a and the back side holding piece 6b do not contact.
More specifically, even if the front side gripping piece 6a and the back side gripping piece 6b are closest, the peak of the front side gripping piece 6a does not contact the valley of the back side gripping piece 6b, and the valley of the front side gripping piece 6a is The back side gripping piece 6b does not come into contact with the mountain.

  Further, since the width W of the supercharging protrusion 15 is smaller than the interval w between the supercharging protrusions 15, the supercharging protrusion 15 of the front side gripping piece 6 a and the supercharging protrusion 15 of the back side gripping piece 6 b are nested, Will not touch.

  The tenter chain 3 and the feeder chain 5 circulate at the same peripheral speed. As shown in FIGS. 3 and 8, the clip 2 and the wave-like gripping members 6a and 6b are both made of a polymer film F. Are disposed at equal intervals so as to be in the same position in the transport direction of the polymer film F. Further, the same number of supercharging protrusions 15 of the wavy gripping members 6a and 6b are provided corresponding to the vertices of the corrugations of the lower tooth portion 11 and the upper tooth portion 12 of the clip 2, respectively.

  Next, the operation of the film stretching machine 1 will be described.

First, the polymer film F is sandwiched between the wavy gripping members 6a and 6b of the film overfeed device 7 and the supercharging protrusions 15 are alternately pressed from above and below, so that each supercharging protrusion 15 is the apex. A waveform is formed (see column B in FIGS. 8 and 13). That is, it relaxes. At this time, since the film F needs to have an extra length as long as it undulates, the film overfeed device 7 has a speed (for example, 1.2 times faster) than the conveying speed (for example, 15 m / sec) of the feeder chain 5. 18 m / sec), the polymer film F is drawn from the upstream side.
The transport speed of the film overfeed device 7 is preferably faster than the transport speed of the feeder chain 5 as described above, and the appropriate speed range is 1.05 times or more and 1.50 times or less of the transport speed of the feeder chain 5. It is.

  When the film overfeed device 7 pulls in the polymer film F from the upstream side, the polymer film F scrapes the supercharging protrusions 15, so that the supercharging protrusions 15 have less friction with the polymer film F. It is desirable to form with such a material. Further, the supercharging protrusion 15 may be a roller that can rotate independently.

  Further, it is ideal that the length of the polymer film F sandwiched between the wave-like gripping members 6a and 6b completely matches the length of the occlusal shape of the lower tooth portion 11 and the upper tooth portion 12 of the clip 2. However, if the polymer film F is supplied in excess of the grip shape of the clip 2, the clip 2 may cause pleats in the polymer film F. In this embodiment, the length of the polymer film F sandwiched between the corrugated gripping members 6a and 6b is adjusted to be slightly shorter than the length of the gripping shape of the clip 2, and the clip (holding member) 2 pulls the polymer film F further from the upstream side when gripping the polymer film F. However, since the length that the clip 2 draws the polymer film F is very small, an excessive force is not applied to the clip guide 14 or the polymer film F is not damaged.

  When the clip 2 reaches the position where the both ends of the polymer film F are completely held, the wavy gripping members 6a and 6b are separated from each other as shown in the row D of FIG. Open.

The film stretching machine 1 undulates and holds the polymer film F with the clip (holding member) 2 even after the wave-like holding members 6 a and 6 b of the film overfeed device 7 release the polymer film F, and conveys the film. . That is, the film stretching machine 1 starts stretching in the transverse direction with a partial region of the polymer film F previously slackened in the longitudinal direction.
The film stretching machine 1 stretches the polymer film F in the width direction by widening the interval between the tenter chains 3 in the heating furnace 4.

  In the film stretching machine 1, each clip (holding member) 2 holds the polymer film F in a corrugated manner, so the polymer film F is stretched in the width direction (for example, 1 to 2 times) in the heating furnace 4. When this is done, the effective portion at the center of the polymer film F can be freely contracted in the longitudinal direction (conveying direction), and no tensile stress is generated in the longitudinal direction. Thereby, the orientation axis (direction of molecular chain) of the polymer film F can be efficiently aligned in the width direction. In addition, since the stress acts in the vertical direction, the vicinity of both side ends of the polymer film F held by the clip 2 is cut off in a subsequent process.

In the film overfeed device 7 shown in FIG. 3 and subsequent figures, the clip 2 that holds the end of the polymer film F is provided, and the clip 2 has a corrugated surface on both the pressing portion 47 side and the film placement surface 45. I am doing. That is, in FIGS. 9, 10, 11, and 13 in the previous embodiment, the clip (holding member) 2 in which both the pressing portion 47 side and the film placement surface 45 are corrugated is illustrated.
However, the clip 2 is not limited to the one in which the pressing portion 47 side and the film mounting surface 45 are corrugated. As shown in FIG. 2, only one of them is a corrugated shape, a tooth profile, etc. May be flat.

14, 15, 16, and 17 show the outer shape and operation when only the pressing portion 47 side is corrugated and the other (film mounting surface 53) adopts a flat plate-like clip 55. . 14 is a perspective view of the clip corresponding to FIG. 9, FIG. 15 is a side view and a plan view of the clip corresponding to FIG. 10, and FIG. 16 is a side view and a plane of the clip corresponding to FIG. FIG. 17 is an explanatory diagram corresponding to FIG. 13.
The clip 55 includes both a convex portion and a concave portion only on one holding member piece. It can be said that the clip 55 is formed by providing convex portions on one holding member piece with a certain interval.

  However, in FIG. 13 of the previous embodiment, the clip 2 is illustrated so as to close slowly in synchronization with the operation of the wavy gripping members 6a and 6b. However, in the embodiment shown in FIG. The clip 2 is in a fully open state until it bites, and after the wave-like gripping member 6 is completely bitten, it is closed by a momentary movement and is shown as holding the polymer film F.

  Since the other structure regarding the clip 55 is the same as the clip 2 mentioned above, the same number is attached | subjected to the same member and the overlapping description is abbreviate | omitted.

The clip 2 having a waveform on both sides as shown in FIGS. 1, 9, 10, 11, and 13 and only one side as shown in FIGS. When compared with a certain clip 55, there are the following advantages and disadvantages.
That is, when both are corrugated like the former, since the polymer film F is stretched while being held in a wide area, the tensile force applied to the film F becomes more uniform.
On the other hand, when both are corrugated like the former, there exists a possibility that a wrinkle may generate | occur | produce in the polymer film F when the waveform of the film F collapses before holding the film F with the clip 2. FIG.
That is, in the previous embodiment, before the polymer film F is held by the clip 2, the polymer film F is shaped into a waveform by the film overfeed device 7. It is ideal that the shaped waveform completely coincides with the clip 2, but the shape of both may slightly differ depending on the thickness and material of the polymer film F. For example, in rare cases, as shown in FIG. 18 (a), a part of the wave shape of the polymer film F may be collapsed. In such a state, the polymer film F is clipped by the clip 2 provided with a waveform on both sides. When the film is sandwiched, a part of the wave is doubled as shown in FIG.

  On the other hand, in the clip 2 in which only one side is corrugated as shown in FIGS. 2, 14, 15, 16, and 17, there is a gap 52 between the pressing portion 47 and the film mounting surface 46 as shown in FIG. Even if a part of the wave shape is broken, the part escapes into the gap 52, and the situation where the polymer film F is doubled is avoided.

  In the embodiment described above, the corrugated gripping member 6 including the front gripping piece 6a and the back gripping piece 6b is used as an apparatus for loosening and corrugating the polymer film F, and sandwiches the polymer film F with this. As a result, the polymer film F was shaped like a wave.

  However, the present invention is not limited to this configuration. For example, a rack-like member and a gear-like member are provided using a member provided with an uneven shape having a structure similar to the rack 58 and the gear 59 as shown in FIG. You may employ | adopt the structure which pinches | interposes the polymer film F in between.

Moreover, you may employ | adopt the structure which pinches | interposes the polymer film F between the two gear-like members (member provided with the uneven | corrugated shape) 60 like FIG.
20 and 21, both surfaces of the polymer film F are pressed at intervals in the transport direction, and a partial region or the entire region of the polymer film F is slackened in the longitudinal direction.

  In the above-described embodiment, the film overfeed device 7 has the wave-like gripping members (front-side gripping pieces and back-side gripping pieces) 6a and 6b, and the polymer film F is sandwiched between the wave-like gripping members 6a and 6b. However, as shown in FIG. 22, a block 61 having only one protrusion is provided, and the polymer film F may press both surfaces with this block 61. Also in the aspect of FIG. 22, both surfaces of the polymer film F are pressed with a gap in the transport direction, and a partial region or the entire region of the polymer film F is slackened in the longitudinal direction.

Further, the surface of the polymer film F may be pressed by the cylinder 62 regardless of the chain. FIG. 23 shows a configuration in which the surface of the polymer film F is pressed by the cylinder 62.
In the configuration shown in FIG. 23, a dancer roll 63 is arranged on the transport path of the polymer film F, and the polymer film F below the cylinder 62 has a degree of freedom in the transport direction with respect to the transport means (not shown). . That is, the polymer film F is given a certain tension by a roll (dancer roll 63) provided so as to be movable up and down (FIG. 23 (a)). However, since the dancer roll 63 has a degree of freedom in the up-and-down direction, when an external force is applied to the polymer film F and pulled in the traveling direction, the dancer roll 63 rises as shown in FIG. Feed out downstream.
In this embodiment, as shown in FIG. 23B, when the surface of the polymer film F is pressed by the cylinder 62, the dancer roll 63 rises and the polymer film F is fed out, and the polymer film F is loosened. The cylinder 62 moves up and down at regular time intervals, the polymer film F is pressed on the surface side with an interval in the transport direction, and a partial region or the entire region of the polymer film F is slackened in the longitudinal direction (FIG. 23C). ).

Moreover, you may make it wavy by pinching the polymer film F with the clip (holding member) 2 irrespective of the film overfeed apparatus 7. FIG.
When the polymer film F is waved by sandwiching the polymer film F with the clip (holding member) 2, a dancer roll 63 is arranged on the transport path of the polymer film F as shown in FIG. It is desirable to give a degree of freedom.

  As yet another measure for wavy (relaxing) the polymer film F, a method of supplying the polymer film F excessively can be considered. For example, as shown in FIG. 25, a plurality of feeding devices 75 are arranged, and the film F is fed in the direction of the arrow by the feeding device 75. And the feed speed of each roll is slowed down to the downstream. As a result, the polymer film F gradually undulates as shown in FIG.

  Next, the polarizer film of the present invention will be described. The polarizer film of the present invention comprises the stretched polymer film of the present invention.

  The polarizer film of the present invention can be produced by any appropriate method depending on the application, the polymer film to be used, conditions, and the like. Typically, a series of processing steps consisting of swelling, dyeing, crosslinking, stretching, washing, and drying steps are employed for the polymer film.

  Among the processing steps, the stretching step is a step that greatly affects the degree of polarization, which is a main characteristic of the polarizer film, and a high degree of uniaxial stretching is required to obtain a high degree of polarization. For this reason, a general polarizer film is often produced by stretching at a high stretching ratio of 5 to 7 times by longitudinal uniaxial stretching that can achieve high uniaxial stretching properties. However, a polarizer film obtained by longitudinal uniaxial stretching has a high degree of polarization, but it has been difficult to widen the width because of a high stretching ratio. Therefore, in order to achieve widening, it is conceivable to simply stretch the polymer film in the transverse direction with respect to the transport direction using a conventional transverse stretching technique. However, when the polymer film is stretched in the lateral direction, it tends to shrink in the transport direction at the same time, so that a tensile stress acts also in the transport direction on the polymer film having both ends fixed by clips or the like. When such a stress in the conveying direction acts, the polymer film will be stretched in the longitudinal direction simultaneously with stretching in the lateral direction, and as a result, high uniaxial stretchability only in the lateral direction cannot be realized. .

  Therefore, in the present invention, since the polymer film can achieve high uniaxial stretchability only in the transverse direction by the above-described method of “stretching in the transverse direction in a relaxed state”, a wide polarizer film can be obtained. Can do.

  Generally, a polarizer film is used so that its absorption axis direction is orthogonal. For example, in a liquid crystal display device, a polarizer film that has been conventionally produced by longitudinal uniaxial stretching is cut into an arbitrary size, aligned so that the respective absorption axis directions are orthogonal, and then bonded to both sides of a liquid crystal panel. ing. Since the polarizer film of the present invention can be used in a roll-to-roll manner through a polarizer film produced by conventional longitudinal uniaxial stretching and a liquid crystal panel, it greatly contributes to a reduction in production cost.

  The polymer film used for the production of the polarizer film of the present invention is not particularly limited as long as it is a polymer film that can be dyed with a dichroic substance (for example, iodine, dichroic dye). Can be used. For example, a polyvinyl alcohol polymer film is particularly preferably used because it is excellent in dyeability with a dichroic substance.

  The light transmittance of the polarizer film of the present invention is preferably 30% to 50%, more preferably 41% to 50%, and most preferably 43% to 50%. The degree of polarization of the polarizer film of the present invention is preferably 97% or more, more preferably 98% or more, and most preferably 99% or more. That is, when the light transmittance is less than 41% or the polarization degree is less than 97%, the brightness and contrast of the liquid crystal display device are low, and the display quality is deteriorated. The thickness of the polarizer in the polarizer film of the present invention is preferably 1 to 50 μm, more preferably 1 to 40 μm, and most preferably 8 to 30 μm.

  Next, the light scattering film of the present invention will be described. The light scattering film of the present invention is composed of the stretched polymer film of the present invention.

  As in the case of the polarizer film described above, from the viewpoint of productivity, in order to achieve widening, when a polymer film is simply stretched in the transverse direction with respect to the transport direction using a conventional transverse stretching technique, Since it tends to shrink in the conveying direction, tensile stress acts also in the conveying direction on the polymer film having both ends fixed by clips or the like. When such stress in the transport direction acts, the polymer film is stretched in the longitudinal direction simultaneously with stretching in the lateral direction, and high uniaxial stretchability only in the lateral direction cannot be realized. For this reason, it becomes a light-scattering film from which the light-scattering property of the part close | similar to the clip holding the polymer film differs from the light scattering property of the center part far from a clip.

  Therefore, in the present invention, by stretching the polymer film in the transverse direction with respect to the polymer film by the above-described method of “stretching in the transverse direction in a relaxed state”, a high degree of uniaxial stretchability in only the transverse direction is achieved. Since this can be achieved, a light scattering film that is wide and has uniform light scattering over the entire surface can be obtained.

  The polymer film used in the production of the light scattering film of the present invention is not particularly limited as long as it is a polymer film having a function of scattering light. For example, a process for physically forming irregularities on the surface of the polymer film. The light scattering film obtained by coating, the light scattering film in which the surface of the polymer film is coated with the light diffusion layer containing fine particles of the organic substance and the inorganic substance, the inorganic film and the organic substance as the light diffusion component in the polymer film A light scattering film in which fine particles are dispersed may be mentioned.

  As a light-diffusion component in the light-scattering film of this invention, a suitable thing is selected suitably according to the objective. Specific examples of inorganic fine particles include mica, synthetic mica, silica, alumina, calcium oxide, titania, zirconium oxide, zinc oxide, magnesium fluoride, smectite, synthetic smectite, vermiculite, ITO (indium oxide / tin oxide). ), ATO (antimony oxide / tin oxide), tin oxide, indium oxide, cadmium oxide and antimony oxide. On the other hand, examples of the fine particles of the organic substance include polymethyl methacrylate, polyacrylonitrile, polyester, silicone, polyethylene, epoxy, melamine / formaldehyde condensate, benzoguanamine / formaldehyde condensate or benzoguanamine / melamine / formaldehyde condensate. Said light-diffusion component is used individually or in combination of 2 or more types.

As for the shape of the fine particles used as the light diffusing component, the elliptical and substantially flat type particles having long and short sides are advanced in a high degree as the particles are stretched in the lateral direction by the production method of the present invention. Therefore, it becomes a particularly good light scattering film.
In addition, fine particles made of an organic substance are particularly good because the shape of the fine particles is deformed along the orientation and has a high degree of orientation as the polymer film is stretched in the transverse direction by the above-described method. It becomes a light scattering film.

  Next, the linear cutting film of this invention is demonstrated. The linear cutting film of the present invention is composed of the stretched polymer film of the present invention.

  As in the case of the polarizer film and the light scattering film described above, when a polymer film is simply stretched in the transverse direction with respect to the transport direction using the conventional transverse stretching technique, it tends to shrink in the transport direction. Also, tensile stress acts on the polymer film fixed at both ends by a clip or the like in the transport direction. When such stress in the transport direction acts, the polymer film is stretched in the longitudinal direction simultaneously with stretching in the lateral direction, and high uniaxial stretchability only in the lateral direction cannot be realized. For this reason, the stretched polymer film is inferior in linear cutting properties.

  Therefore, in the present invention, by stretching the polymer film in the transverse direction with respect to the polymer film by the above-described method of “stretching in the transverse direction in a relaxed state”, a high degree of uniaxial stretchability in only the transverse direction is achieved. Since this can be achieved, it is possible to obtain an excellent linear cutting film having uniform linear cutting properties over the entire surface.

  It does not restrict | limit especially as a polymer film used for manufacture of the linear cutting film of this invention, Various polymer films can be used. For example, a polymer film composed of a polyethylene resin and a polypropylene resin is particularly preferably used because of excellent processability and oxygen barrier properties.

  The present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the examples. In addition, the measurement methods of various physical properties and optical characteristics are as follows.

(1) Polarization degree Using a spectrophotometer [Murakami Color Research Laboratory Co., Ltd., device name “DOT-3”], the parallel transmittance (T0) and the orthogonal transmittance (T90) were measured, and the following formula:
Polarization degree (%) = {(T0−T90) / (T0 + T90)} 1/2 × 100
Determined by The parallel transmittance (T0) was obtained by measuring a transmittance obtained by superposing two polarizers so that their absorption axes are parallel to each other. The orthogonal transmittance (T90) was obtained by measuring the transmittance obtained by superposing two identical polarizers so that their absorption axes are orthogonal to each other. Note that these transmittances are Y values obtained by correcting the visibility using the 2-degree field of view (C light source) of JlSZ8701-1982.

(2) Uniformity of light scattering The positive fluctuation rate (see the following formula) or negative fluctuation rate (see the following formula) of the haze value measured at intervals of 50 mm in the lateral direction of the optical film is within 3%. “◯” and those exceeding 3% were evaluated as “x”. About haze, it measured using the integrating sphere type haze meter [Nippon Denshoku Co., Ltd. apparatus name "300A"] according to JISK7105.
Rate of change on the plus side (%) = 100 × (maximum value−average value of all measured values) / (average value of all measured values)
Minus fluctuation rate (%) = 100 × (average value of all measured values−minimum value) / (average value of all measured values)

(3) Straight cut property Two samples each having a length of 300 mm in the horizontal direction and 180 mm in the transport direction are cut out from each of the two ends and the center of the film, and a line exactly parallel to the horizontal direction is drawn at intervals of 30 mm. It was. Next, on this line, a new cutter blade was used to make a cut from the end to 50 mm to form a strip, which was used as a test piece. Next, the test piece was placed on the flat desk in the direction where the lateral direction was straight forward in front of the measurer. Next, the right hand held the strip portion at the right end of the test piece, and the left hand held the strip portion next to it. The right hand with the strip was slowly pulled straight forward. This operation was performed five times in order from the right end.
200 mm from the beginning of the tear, the width deviated from the line drawn in the horizontal direction in advance, that is, the straight line is drawn in the horizontal direction, and the absolute value of the deviation from the straight line when it is torn 200 mm is L (mm), It was used as an index of straight cut property.
Among the six points at both ends and the center, the largest value of L was selected, and those having a value of L of 5.0 mm or less were evaluated as “◯”, and those exceeding 5.0 mm were evaluated as “X”.

[Example 1]
Using the clip 2 shown in FIG. 2 and the film stretching machine 1 shown in FIG. 3 and the film overfeed device 7 shown in FIGS. It dye | stained in the dyeing bath of the 5 wt% iodine compound aqueous solution hold | maintained both ends of the polyvinyl alcohol-type polymer film (Average polymerization degree 2400, Saponification degree 99.9 mol%), and hold | maintained at 30 +/- 3 degreeC. Subsequently, while performing a crosslinking reaction in an aqueous solution bath containing 4 wt% boric acid and 3 wt% potassium iodide maintained at 60 ± 3 ° C., the polyvinyl alcohol polymer film was 450% transverse to the transport direction. It extended | stretched so that it might become. The obtained stretched polymer film was dried for 10 minutes in an air circulating constant temperature oven at 40 ± 1 ° C. to obtain a polarizer film having a thickness of 28 μm. The properties of the obtained polarizer film were as shown in Table 1. The “slack amount” in Table 1 indicates the slack amount in the film transport direction. For example, when the length in the transport direction is 400 mm and the slack amount is 100%, the film is slack 400 mm. “Stretch ratio” in Table 1 indicates a transverse stretch ratio with respect to the original fabric width. For example, when the original fabric width is 500 mm and the stretch ratio is 100%, the post-stretch width is 1000 mm.

[Example 2]
The film was stretched in the transverse direction in the same manner as in Example 1 except that the film was slackened to 250% and stretched so that the stretching ratio in the transverse direction was 450%. The properties of the obtained polarizer film were as shown in Table 1.

Example 3
The film was stretched in the transverse direction in the same manner as in Example 1 except that the film was slackened to 300% and stretched in the transverse direction to 500%. The properties of the obtained polarizer film were as shown in Table 1.

Example 4
Using the clip 2 shown in FIG. 2, the film stretching machine 1 shown in FIG. 3, and the film overfeed device 7 shown in FIGS. Holds both ends of a polycarbonate film (polymer film) having a thickness of 70 μm to which 3.0 wt% of fine particles of methacrylate (average particle diameter of 8 μm) are added, and is 35 ° lateral to the conveying direction at 140 ° C. ± 1 ° C. % Stretching was performed. The properties of the obtained light scattering film (polymer stretched film) were as shown in Table 2. The “sag amount” and “stretch ratio” in Table 2 have the same meaning as in Table 1.

Example 5
Implemented except that a polycarbonate film (polymer film) with a thickness of 60 μm to which 4 wt% of silica fine particles (average particle diameter of 4 μm) were added, the amount of looseness was 20%, and the transverse draw ratio was 22% In the same manner as in Example 4, stretching was performed in the transverse direction. The properties of the obtained light scattering film (polymer stretched film) were as shown in Table 2.

Example 6
Using the clip 2 shown in FIG. 2, the film stretching machine 1 shown in FIG. 3, and the film overfeed device 7 shown in FIGS. The both ends of the polypropylene film (polymer film) were held and stretched 45% in the transverse direction to the conveying direction at 140 ° C. ± 1 ° C. The properties of the obtained linear cutting film (polymer stretched film) were as shown in Table 3. The “sag amount” and “stretch ratio” in Table 3 have the same meaning as in Table 1.

Example 7
The film was stretched in the transverse direction in the same manner as in Example 6 except that the film slack amount was 20% and the film was stretched so that the stretching ratio in the transverse direction was 25%. Table 3 shows the characteristics of the obtained linear cutting film.

[Comparative Example 1]
The film was stretched in the transverse direction in the same manner as in Example 1 except that the amount of film sag was 0%. The properties of the obtained polarizer film were as shown in Table 1.

[Comparative Example 2]
The film was stretched in the transverse direction in the same manner as in Example 3 except that the amount of film sag was 0%. The properties of the obtained polarizer film were as shown in Table 1.

[Comparative Example 3]
The film was stretched in the transverse direction in the same manner as in Example 4 except that the amount of film sag was 0%. The properties of the obtained light scattering film were as shown in Table 2.

[Comparative Example 4]
The film was stretched in the transverse direction in the same manner as in Example 5 except that the amount of film sag was 0%. The properties of the obtained light scattering film were as shown in Table 2.

[Comparative Example 5]
The film was stretched in the transverse direction in the same manner as in Example 6 except that the amount of film sag was 0%. Table 3 shows the characteristics of the obtained linear cutting film.

[Comparative Example 6]
The film was stretched in the transverse direction in the same manner as in Example 7 except that the amount of film sag was 0%. Table 3 shows the characteristics of the obtained linear cutting film.

2 Clip (holding member)
6 Wavy gripping member 6a Front side gripping piece 6b Back side gripping piece 11 Lower teeth (holding member piece, wavy gripping member)
12 Upper teeth (holding piece)
55 Holding member 56 Upper tooth part (holding member piece)
57 Plane (holding piece)
F polymer film

Claims (6)

It is a polymer stretched film obtained by a method of transporting while holding both ends of a long polymer film that is continuously supplied, and stretching the polymer film in a direction transverse to the transport direction while transporting the polymer film. ,
The method
A step of loosening both ends of the polymer film by a member provided with an uneven shape;
A holding step of holding both ends of the loose polymer film in the transport device;
A stretching step of stretching the polymer film in the transverse direction by widening in the transverse direction with respect to the transport direction while transporting the polymer film by the transport device;
A polymer stretched film characterized by comprising:   In the method, the polymer film is held in the transverse direction by holding the end of the polymer film with a holding member piece having a concavo-convex holding member piece in a state in which a partial region or the entire region of the polymer film is slackened in the transport direction. The stretched polymer film according to claim 1, which starts.   The method is to start stretching in a transverse direction in a state where a partial region or the entire region of the polymer film is loosened by alternately pressing one surface and the other surface of the polymer film. The stretched polymer film according to claim 1 or 2, characterized in that   A polarizer film comprising the polymer stretched film according to claim 1.   The light-scattering film which consists of a polymer stretched film in any one of Claims 1-3.   The linear cutting film which consists of a polymer stretched film in any one of Claims 1-3.

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