JP5528413B2 - Film winding method, film manufacturing method, and polarizing plate manufacturing method - Google Patents

Description

  The present invention relates to a film winding method, a film manufacturing method, and a polarizing plate manufacturing method.

  Conventionally, various films such as an optical film have been used. As a method for producing these films, for example, there is a method of forming films having various functions by applying a coating liquid to a long support and forming a coating film. The long support itself can also be said to be a kind of film.

  All of these films are wound up, temporarily stored in the form of film rolls, and sent to the next step.

  Thus, the film winding always occurs, and the film winding process is an indispensable process in the production of the film.

  As such a film winding method, Patent Document 1 discloses a straight winding process in which the film is wound around a winding core so that the side edges of the film are aligned, and after the straight winding process, the side edges are formed on the film. And an oscillating winding step of winding the film around the core by periodically vibrating the film or the core in the width direction of the film so as to periodically shift in a certain range with respect to the width direction. The winding method is described.

  Thereby, it is supposed that it can wind up so that an ear | edge extension and winding shift | offset | difference may not arise in the film roll after winding.

JP 2010-150041 A

  However, in the film winding method described in Patent Document 1, it is impossible to eliminate a defect called blocking or black band, which occurs when the convex portions of the film adhere and adhere to each other in the film roll.

  In view of such circumstances, the present invention intends to provide a film winding method and a film manufacturing method capable of simultaneously reducing both black band defects and winding misalignment defects.

  The problems of the present invention can be solved by the following inventions.

  That is, the film winding method of the present invention is a film winding method for winding a film on a winding shaft to a predetermined thickness, and is wound around the winding shaft by rotating the winding shaft. A winding step of winding the film around the winding shaft, and a sliding step of reciprocally sliding the winding shaft relative to the film immediately before winding in the width direction of the film during the winding step; In the slide step, when the thickness of the film wound around the take-up shaft during the reciprocating slide of the take-up shaft is taken as a period, the predetermined amount from when the film starts to be wound on the take-up shaft. The half thickness of the predetermined thickness than the average value of the period until the film is wound up to half the thickness of A relative slide speed, which is a relative slide speed of the winding shaft with respect to the film immediately before winding, and the winding so that an average value of a period from winding to a predetermined thickness is increased. The main feature is that at least one of the rotational speeds of the shaft is controlled.

  This can reduce both black band defects and winding misalignment defects.

  Further, in the film winding method of the present invention, in the slide step, the relative slide is performed so that the period gradually increases from when the film is wound around the winding shaft until the film is wound up to the predetermined thickness. The main feature is that at least one of the speed and the rotational speed of the winding shaft is controlled.

  Thereby, both the black band defect and the winding deviation defect can be further reduced.

  Moreover, the film manufacturing method of the present invention is a film manufacturing method for manufacturing a film with a coating film, the step of applying a coating liquid to a long support, and the film with a coating film by drying the applied coating liquid And a step of winding the coated film by any one of the above-described winding methods.

  Thereby, the film which reduced both the black band defect and the winding gap defect can be manufactured.

  Furthermore, the polarizing plate manufacturing method of the present invention is a manufacturing method of a polarizing plate in which a protective film is bonded to at least one surface of a polarizer, and the protective film is wound into a roll shape by any one of the above winding methods. A winding step, a winding step of unwinding the wound-up protective film, and bonding the unwound protective film to at least one surface of the polarizer; and the polarizer to which the protective film is bonded And a cutting step of cutting to the dimension.

  Both black band defects and winding misalignment defects can be reduced.

It is the schematic showing a film manufacturing line. It is the cross-sectional schematic of the width direction of the film wound up by the winding shaft. It is the cross-sectional schematic diagram of a part of the wound film.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions. In addition, in the present specification, when a numerical range is expressed using “˜”, upper and lower numerical values indicated by “˜” are also included in the numerical range.

<Film production line>
The film production line according to the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a film production line. As shown in FIG. 1, the film production line 10 according to the present invention mainly includes a film production apparatus 20 and a winding apparatus 30.

  In FIG. 1, the film manufacturing apparatus 20 is extremely simplified and described as a simple box because various apparatuses are conceivable as the film manufacturing apparatus 20. For example, the film manufacturing apparatus 20 may be one that manufactures a support by a melt film forming method, a solution film forming method, or the like, or an apparatus that manufactures a film by applying a coating liquid on the support. However, the present invention is not limited thereto, and any film (or support) can be produced as long as the film (or support) is finally wound by a winding device. Good.

  Here, a case where the film manufacturing apparatus 20 is a slot die type coating apparatus will be described as an example. The film manufacturing apparatus 20 which is a slot die coating apparatus supplies the coating liquid to a support traveling from the slot and performs coating. The coating liquid supplied onto the support forms a thin film on the support and is then dried, whereby the solvent component in the coating liquid evaporates and a coating film containing only the solid component is formed.

  Here, the knurling part 42 which is a part in which minute irregularities are formed in advance is formed at both side ends of the support. The slot die coating apparatus also coats the knurling part 42 with a coating solution to form a coating film.

  Next, the winding device 30 will be described. The winding device 30 mainly includes a winding shaft 60, a pair of arms 70, a motor (not shown), an oscillating unit 62, and a control unit (not shown).

  The winding shaft 60 winds the film 40 supplied from the film manufacturing apparatus 20 by rotating the guide roller 50. The arm 70 holds the winding shaft 60 from both sides in the longitudinal direction. The motor rotates the winding shaft 60. The oscillating portion is slid back and forth in the direction indicated by the arrow 90 (the width direction of the film 40).

  The oscillating unit 62 may be configured by, for example, an oscillating motor 61, an eccentric cam 64, and a spring 66. In this case, the oscillating motor 61 rotates the eccentric cam 64, and the eccentric cam 64 pushes the arm 70 biased in the direction of the eccentric cam 64 by the spring 66, so that the arm 70 is slid back and forth. The oscillating portion shown here is merely an example, and any structure or method for winding while reciprocating sliding may be adopted.

  Further, in FIG. 1, the oscillating portion 62 shows a method of reciprocatingly sliding the take-up shaft 60 by reciprocatingly sliding the arm 70. However, the present invention is not limited to this. You may employ | adopt the method to make it.

  Here, the oscillating unit that reciprocally slides the winding shaft is shown, but the present invention is not limited to this, and a method of reciprocatingly sliding the transport position of the film 40 may be adopted. That is, a method in which the take-up shaft 60 slides reciprocally relative to the film 40 immediately before being taken up can be adopted. In this case, the oscillating portion reciprocally slides the film 40 immediately before being wound on the winding shaft 60.

  In the present invention, the reciprocal sliding relative to the film immediately before the take-up shaft is taken up is referred to as oscillating. The control unit controls the rotation speed, oscillation speed, and oscillation movement amount (reciprocating slide amount) of the winding shaft 60.

<Film winding method>
The film winding method of the present invention is characterized in that it oscillates when the film 40 is wound, and is particularly characterized in the oscillating method. Therefore, the oscillating method according to the present invention will be described in more detail with reference to FIGS. FIG. 2 is a schematic cross-sectional view in the width direction of the film wound on the winding shaft. FIG. 3 is a schematic cross-sectional view of a part of the wound film.

  When the film 40 is wound around the winding shaft 60, the film 40 is wound while oscillating. Therefore, both ends of the cross-section in the width direction of the wound film 40 have a zigzag shape as shown in FIG. doing. Here, since the width of the film 40 is the same, in the zigzag peak and valley, when the right end is a peak, the left end is a valley, and when the right end is a valley, the left end is a peak. Become.

  As shown in FIG. 2, in the present invention, the apex and apex width of the peak portions adjacent to each other in the vertical direction are referred to as a period, and the width between the bottom of the trough portion and the apex of the peak portion (passing through the bottom of the trough portion, The shortest distance between the straight line perpendicular to the rotation axis of the take-up shaft 60 and the straight line passing through the apex of the peak adjacent to the valley and perpendicular to the take-up shaft 60 is called amplitude.

  In other words, the period is the thickness of the film wound around the take-up shaft 60 while the take-up shaft 60 is slid back and forth, and the amplitude is half of the distance that the take-up shaft 60 is moved back and forth once. That is, the distance of the one-way slide, not the reciprocation.

  Here, the cycle is controlled by the relative slide speed (hereinafter simply referred to as slide speed) with respect to the film immediately before the take-up shaft 60 is taken up and the take-up speed (rotational speed) of the take-up shaft 60. This is accomplished by controlling at least one of them. The amplitude can be controlled by controlling a relative slide amount (hereinafter simply referred to as a slide amount) with respect to the film immediately before the take-up shaft 60 is taken up.

  In the present invention, the side closer to the take-up shaft 60 is oscillated so that at least the period is smaller and / or the amplitude is larger than the far side. When the period is small, it is preferable that the period gradually increases from the side closer to the winding shaft 60 toward the outer side. When the amplitude is large, the amplitude gradually increases from the side closer to the winding axis 60 toward the outer side. Is preferably small.

  Thereby, both a defect called a blocking or a black band (referred to as a black band defect in the present invention) and a winding deviation defect can be reduced. Here, the black belt defect and the winding deviation defect will be described below.

  FIGS. 3A and 3B show schematic cross sections of several layers of film when 40 films are wound. When the film 40 is wound around the take-up shaft 60, the convex portions 100 in the film 40 may overlap at the same position as shown in FIG. In this case, as the product is wound many times, pressure is strongly applied to the convex portion 100, and the quality of the product deteriorates due to adhesion of this portion or generation of extension due to pressure. become. Moreover, when this part is seen from the outside, it looks like a black belt. This is a black belt defect.

  Therefore, as shown in FIG. 3B, when the film 40 is wound up while being oscillated, the convex portion 100 is displaced, so that the occurrence of a black belt defect can be prevented. However, by winding while oscillating, the adhesiveness deteriorates, so that winding misalignment is likely to occur. The winding misalignment refers to a defect in which the positions of both side ends of a film roll that is wound with a film are partially deviated from the initial position after winding.

  This winding misalignment and black belt defect are in a conflicting relationship with each other, so reducing one defect will increase the other defect and reduce both defects simultaneously. It was difficult. In other words, the winding misalignment can be prevented as it is wound more closely, but it tends to be a black belt defect, and if it is wound without being closely attached, it is difficult to cause a black belt defect, but a winding misalignment is likely to occur.

  As a result of diligent research, the present inventor has found that both the winding misalignment and the black belt defect can be simultaneously reduced by changing the cycle and amplitude of the oscillation by a specific method.

<Evaluation>
The film was wound up by changing the oscillate, and evaluation for producing a film roll was performed. In Comparative Examples 1 to 4, film rolls were produced without changing the period and amplitude of the oscillate. In Examples 1 to 4, film rolls were produced by changing the period or amplitude.

  The produced film roll was examined for black belt defects and winding misalignment. The black belt defect was expressed in four levels: ◎ (none), ○ (very weak), △ (weak), and × (strong) after adhesion. Regarding the winding misalignment, whether the winding misalignment occurred by moving the film roll in the axial direction of the film roll and suddenly stopping the film roll was examined. The occurrence of winding misalignment was expressed in four stages: ◎ (strong), ○ (slightly strong), △ (slightly weak), and x (weak) in the order of difficulty in winding misalignment, that is, in the order of strong winding misalignment resistance. Here, from ◎ to △ are in the range of non-defective products and are not defective in any case. Only x is defective. The evaluation contents and evaluation results are shown in Table 1, and the meanings of the evaluation result symbols are shown in Table 2.

  Referring to Table 1, as described in the remarks, the period “5 → 15” of Example 1 is the average value of the oscillating period on the winding core side from the center of the film roll thickness, that is, the film roll In the thickness direction, the average value of the oscillating period between the portion between the portion closest to the winding core and the outermost portion to the portion closest to the winding core (hereinafter simply referred to as the center-winding core portion) is 5 mm. The average value of the oscillating period on the outer peripheral side of the center of the roll thickness, that is, between the middle and the outermost part between the part closest to the winding core and the outermost part in the thickness direction of the film roll (hereinafter simply referred to as the center) -The average value of the oscillating period (referred to as the outer part) is 15 mm, and in the thickness direction of the film roll, the oscillating period gradually increases from the winding core side toward the outermost side. .

  The cycle “2 → 15” in the third embodiment has the same meaning as the cycle “5 → 15” in the first embodiment except that the numerical values are different.

  In addition, the amplitude of “15 → 5” in Example 4 is an average value of the center-winding portion oscillating amplitude of 15 mm, an average value of the center-outside oscillating amplitude of 5 mm, and the film roll In the thickness direction, the oscillating amplitude gradually decreases from the winding core side toward the outermost side.

  In addition, as described in the remarks, “5/15” in Example 2 has a constant center-winding core oscillating period of 5 mm and a constant central-outer oscillating period of 15 mm. It is shown that.

  Similarly, “15/5” in Example 5 indicates that the oscillation amplitude of the center-winding core portion is constant at 15 mm, and the oscillation amplitude of the center-outside portion is constant at 5 mm.

  A black belt defect is more likely to occur as the winding tension is larger, and a winding misalignment is more likely to occur as the winding tension is smaller. In Comparative Examples 1 to 4 in Table 1, when the winding tension is as large as 400N, the black belt defect is x, when it is 350N, it is Δ, and when it is 300N, it is ○.

  On the other hand, in Examples 1 to 4 in which the cycle or amplitude of the oscillation is changed, the black belt defect is 帯 or Δ even though the winding tension is as large as 500N.

  Further, the winding misalignment in Comparative Examples 1 to 4 is x when the winding tension is small, 300N, and is Δ, when 350N. On the other hand, in Examples 1 to 4, all are ◎ or ○.

  Referring to Example 1, the black belt defect was ◎ and the winding deviation was also ◎, and good results were obtained. Comparing Example 1 and Example 2, in Example 1, the winding misalignment is also ◎, whereas in Example 2, the winding misalignment is ○. Therefore, it can be seen that the winding misalignment can be further reduced by gradually changing the oscillation cycle.

  Comparing Example 1 and Example 3, in Example 1, the cycle of the oscillation is 5 → 15 and the black belt defect is ◎, whereas in Example 3, the cycle is 2 → 15 and the black belt defect is △. Therefore, it can be seen that the effect of reducing the black belt defect is larger when the oscillation period of the center-winding core portion is 5 mm (about 83 times the film thickness) than 2 mm (about 33 times the film thickness).

  When Example 1 and Example 4 are compared, both have a black belt defect ◎ and a winding misalignment defect ◎. Therefore, even if the average value of the oscillating period is changed from 5 mm (center-core part) to 15 mm (center-outer part), the average value of oscillating amplitude is changed from 15 mm (center-core part) to 5 mm (center-outer part). It can be seen that both the black band defect and the winding misalignment can be reduced even when the change is made to (1). From these, it is clear that good results can be obtained even if both the oscillation period and the amplitude are changed simultaneously.

  Comparing Example 4 and Example 5, in Example 4, the winding misalignment is also ◎, whereas in Example 5, the winding misalignment is ○. Therefore, it can be seen that winding deviation defects can be further reduced by gradually changing the oscillation amplitude.

  From the above, it has been found that black band defects and winding misalignment defects can be reduced by increasing the average value of the center-outer part oscillating period than the average value of the center-winding part oscillating period. At this time, it was found that black band defects and winding misalignment can be further reduced by gradually increasing the oscillating period from the core side toward the outside.

  It has also been found that black band defects and winding misalignment can be reduced by making the average value of the oscillating amplitude at the center-outer part smaller than the average value of the oscillating amplitude at the center-winding core part. At this time, it has been found that black band defects and winding deviation defects can be further reduced by gradually decreasing the oscillation amplitude from the winding core side toward the outside.

  Further, according to the research of the present inventors, it is found that the average oscillating period of the center-winding core part is 40 to 250 times the film thickness, and the average oscillating period of the center-outer part is preferably 80 to 1000 times the film thickness. It was. At this time, it was also found that the average oscillating period of the center-outer part is more preferably 3% or more than the average oscillating period of the center-winding core part. Furthermore, at this time, it has been found that it is most preferable that the oscillating period gradually changes from the winding core side to the outside.

  Similarly, for the average oscillation amplitude, the average oscillation amplitude of the center-core portion is 1.5 to 4 times the knurling width of the film edge or the film formed on the knurling, It has been found that the average oscillating amplitude is preferably 0.01 to 2 times the knurling width at the film edge or the film formed on the knurling. At this time, it was also found that the average oscillating amplitude at the center-outer portion is more preferably 3% or more smaller than the average oscillating amplitude at the center-winding core portion. Furthermore, at this time, it has been found that it is most preferable that the oscillating period gradually changes from the winding core side to the outside.

<Production method of polarizing plate>
Next, the manufacturing method of the polarizing plate using the film winding method which concerns on this invention is demonstrated. A polarizing plate is one in which a protective film is laminated on one side or both sides of a deflector.

  Examples of the polarizer include hydrophilic polymers such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. Examples thereof include polyene-based oriented films such as those obtained by adsorbing volatile substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.

  As a material for forming the protective film laminated on one side or both sides of the deflector, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) -Based polymer, polycarbonate-based polymer and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the protective film.

  As materials for forming the protective film, those mentioned above can be considered, but in consideration of deflection characteristics and durability, a cellulose-based polymer such as TAC (triacetyl cellulose) is preferable, and a TAC film is particularly preferable.

  Further, a hard coat layer may be provided on the surface of the protective film to which the polarizer is not adhered, or a treatment for antireflection treatment, diffusion or antiglare may be performed.

  If the manufacturing method of the polarizing plate using the film winding method which concerns on this invention is demonstrated, a protective film will be manufactured in the film manufacturing line mentioned above, and a protective film will be wound up in roll shape using the winding method of this invention.

  Next, the protective film wound up in a roll shape and the polarizer wound up in a roll shape are unwound, and the protective film is bonded to one or both sides of the polarizer. When bonding a protective film to both surfaces of a polarizer, two rolls of the protective film wound up in roll shape can be used, and a protective film can be simultaneously bonded to both surfaces of a polarizer.

  A water-based pressure-sensitive adhesive or the like can be used for adhesion between the polarizer and the protective film. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester.

  Next, the polarizer to which the protective film is bonded is cut into a predetermined size. In this way, a polarizing plate cut to a predetermined size can be produced.

  DESCRIPTION OF SYMBOLS 10 ... Film production line, 20 ... Film production apparatus, 30 ... Apparatus, 40 ... Film, 42 ... Knurling part, 50 ... Guide roller, 60 ... Winding shaft, 61 ... Oscillation motor, 62 ... Oscillation part, 64 ... Eccentric cam , 66 ... Spring, 70 ... Arm, 100 ... Projection

Claims (4)

A film winding method for winding a film on a winding shaft to a predetermined thickness,
A winding step of winding the film wound around the winding shaft around the winding shaft by rotating the winding shaft;
A slide step of reciprocally sliding the take-up shaft relative to the film in the width direction with respect to the film immediately before taking-up during the take-up step;
In the sliding step, if the thickness of the film wound on the winding shaft while the winding shaft is slid once and reciprocally is defined as a period, the predetermined thickness from when the film starts to be wound on the winding shaft. The average value of the period until the film is wound up from the half thickness of the predetermined thickness to the predetermined thickness is larger than the average value of the period until the film is wound up to half the thickness. The film winding method in which at least one of a relative slide speed that is a relative slide speed of the winding shaft with respect to the film immediately before winding and a rotational speed of the winding shaft is controlled.   In the sliding step, the relative sliding speed and the rotational speed of the winding shaft are increased so that the period gradually increases from when the film is wound on the winding shaft until the film is wound to the predetermined thickness. The film winding method according to claim 1, wherein at least one is controlled. A film manufacturing method for manufacturing a film with a coating film,
Applying a coating solution to a long support;
Drying the applied coating solution to form a coated film; and
Winding the film with a coating film by the film winding method according to claim 1 or 2 ,
A method for producing a film. A method for producing a polarizing plate in which a protective film is bonded to at least one surface of a polarizer,
A winding step of winding the protective film in a roll shape by the film winding method according to claim 1 or 2 ,
Unwinding the wound-up protective film and bonding the unwound protective film to at least one surface of a polarizer;
A cutting step of cutting the polarizer to which the protective film is bonded into a predetermined size;
The manufacturing method of the polarizing plate provided with.

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