JP6679268B2 - Method for manufacturing laminated optical film - Google Patents

Description

  The present invention relates to a method for producing a laminated optical film, and more particularly to a method for producing a laminated optical film including a step of laminating films via an adhesive layer.

  Various laminated optical films are used in optical devices such as image display devices (liquid crystal display devices, organic EL display devices, etc.), and one typical example thereof is a polarizing plate used in liquid crystal display devices and the like. Is. In the present specification, the laminated optical film means a laminated body composed of a plurality of films, and at least one of the films constituting the laminated body is an optical film. The optical film refers to a film used for optical applications such as being used as a member of an optical device.

  A polarizing plate is usually manufactured by laminating a protective film on one side or both sides of a polarizing film using an adhesive. In the step of sticking with an adhesive, a device has been conventionally devised in order to prevent the adhesive from leaking from the sticking surface.

  For example, in Japanese Patent Laid-Open No. 2006-88651 (Patent Document 1), an adhesive liquid is supplied to a bonded portion, and a liquid that resists the adhesive liquid that tends to flow toward the edge of the film is supplied from the edge of the film. In addition, it is described that the adhesive liquid diluted with such liquid is removed by suction before bonding. Japanese Unexamined Patent Application Publication No. 11-179871 (Patent Document 2) describes that air is blown to bring the adhesive liquid to the central portion in the width direction and the excessively supplied adhesive is suctioned and removed in advance.

JP, 2006-88651, A JP, 11-179871, A

  However, even by the above method, the adhesive may leak from the edge of the film and may contaminate the film or the manufacturing apparatus.

  Then, the objective of this invention is providing the manufacturing method of the laminated optical film which can prevent an adhesive agent from leaking out from the edge of a film effectively.

The present invention provides the following method for producing a laminated optical film.
[1] A method for producing a laminated optical film having at least two laminated films including a first surface film and a second surface film,
A film having the first surface film forming one surface, the second surface film forming the other surface, and an adhesive layer provided between the first surface film and the second surface film. Lamination, passing between a pair of rolls, a laminating step of applying pressure to the film laminate,
And a suction step of sucking excess adhesive that moves toward both widthwise ends of the film laminate by the pressure.

  [2] The method for producing a laminated optical film according to [1], wherein in the suction step, the arrangement position of the suction port of the suction unit that sucks the adhesive is variable.

  [3] The width of the first surface film and the second surface film is longer than the surface length of the pair of rolls, and the portions that do not come into contact with the pair of rolls in the laminating step are widthwise opposite ends. The method for producing the laminated optical film according to [1] or [2].

  [4] In the suction step, suction ports of suction means for sucking the adhesive are inserted into the space between the first surface film and the second surface film at both widthwise ends of the film laminate. The method for producing a laminated optical film according to [3].

[5] The laminated optical film has at least one inner film laminated between the first surface film and the second surface film,
The widths of the first surface film and the second surface film are longer than that of the inner film, and in the laminating step, portions having no inner film are provided at both end portions in the width direction, [1] to [1]. [4] The method for producing a laminated optical film according to any one of [4].

  [6] The laminated optical film according to any one of [1] to [5], wherein in the suction step, a liquid for diluting the sucked adhesive is supplied and the diluted adhesive is sucked. Production method.

  In the method for producing a laminated optical film of the present invention, it is possible to prevent the adhesive from leaking from the edges of the film.

It is a side view which shows typically an example of the manufacturing method and manufacturing apparatus used for the laminated optical film which concern on this invention. It is a side view which shows typically another example of the manufacturing method of the laminated optical film which concerns on this invention, and the manufacturing apparatus used for it. FIG. 2 is a top perspective view of the vicinity of the pair of bonding rolls of the manufacturing apparatus shown in FIG. 1. It is a figure which shows typically an example of a structure of the front-end | tip of a suction nozzle. It is a figure which shows an example of the positional relationship of the laminated optical film and the suction port of a suction nozzle. It is a figure which shows an example of the positional relationship of the laminated optical film and the suction port of a suction nozzle. It is a figure which shows an example of the positional relationship of the laminated optical film and the suction port of a suction nozzle. It is a figure which shows the moving direction of the adhesive agent in a bonding process, and (a), and the flow (b) of the surrounding atmosphere estimated by the suction of a suction nozzle, when a suction port is inserted between two films. . When the suction port is arranged at a position that substantially coincides with the end faces of the two films, the moving direction of the adhesive in the bonding step (a) and the flow of the ambient atmosphere predicted by the suction of the suction nozzle (b) ) Is a figure which shows.

  The present invention relates to a method for producing a laminated optical film having at least two laminated films including a first surface film and a second surface film. At least one of the films constituting the laminated optical film is an optical film. For example, at least one of the first surface film and the second surface film is an optical film, and typically both are optical films. The laminated optical film obtained by the method of the present invention is an optical member used as one member of an optical device such as an image display device (a liquid crystal display device or the like), and one representative example thereof is a polarizing plate. The polarizing plate is provided with at least a polarizing film and a protective film as films constituting the polarizing plate.

[Method for producing laminated optical film]
The method for producing a laminated optical film of the present invention comprises the following steps:
A laminating step of passing a film laminate, in which a first surface film and a second surface film are laminated via an adhesive layer, between a pair of rolls, and applying pressure to the film laminate; and the pressure. And a suction step of sucking excess adhesive that moves toward both ends in the width direction of the film laminate.

  Further, before the laminating step, an injection step of injecting an adhesive between the first surface film and the second surface film to form an adhesive layer may be included. Further, a curing step of curing or drying the adhesive layer can be included after the suction step. The adhesive layer formed between the first surface film and the second surface film is formed by bonding two films facing each other with the adhesive interposed. When the films constituting the laminated optical film are only the first surface film and the second surface film, the adhesive layer is formed to bond the first surface film and the second surface film, and further another film. When it has (inner film), it is formed to bond two adjacent films. When the number of films constituting the laminated optical film is three or more, it is necessary to form an adhesive layer between the films that need to be bonded with an adhesive, and therefore, two or more adhesive layers are formed. There is.

  Hereinafter, the method for producing a laminated optical film according to the present invention will be described in detail with reference to FIGS. 1 and 2. 1 and 2 are side views showing an example of a method for manufacturing a laminated optical film according to the present invention and a manufacturing apparatus used for the same. FIG. 1 shows a method for producing a laminated optical film in the case of laminating two sheets, that is, a method for producing a laminated optical film composed of two sheets of a first surface film and a second surface film. FIG. 2 shows a method for producing a laminated optical film in the case of laminating three sheets, that is, a method for producing a laminated optical film having a first surface film and a second surface film and an inner film therebetween. In general, a laminated optical film such as a polarizing plate can be continuously obtained as a long product by performing a process in each step while continuously unwinding and transporting a long film as shown in FIG. It can be manufactured. However, the production method of the present invention is not limited to the continuous production using such a long film, and may be a method using a sheet film.

  First, using FIG. 1, a polarizing plate (laminated optical film) is manufactured by laminating two sheets in which a first protective film 20 (first surface film) is laminated on one surface of a polarizing film 10 (second surface film). I will explain how to do it.

  In the manufacturing method shown in FIG. 1, first, a roll (rolled product) of a long polarizing film 10 and a roll of a long first protective film 20 are prepared, and these are continuously fed using a unwinding device (not shown). The film is conveyed while unwinding. Each film is conveyed such that the longitudinal direction thereof is the conveying direction. A guide roll 60 that supports the traveling film is appropriately provided in the film transport path. The arrow in FIG. 1 indicates the film transport direction or the rotation direction of various rolls.

<Injection process>
In this step, an adhesive is injected between the polarizing film 10 and the first protective film 20 by using the injection device 30 to form an adhesive layer (not shown). The device for interposing the adhesive layer is not limited to the injection device 30 as shown in FIG. 1, and for example, depending on the viscosity of the adhesive, a doctor blade method, a wire bar coating method, Appropriately select a coating method such as die coating method, comma coater method, gravure coating method, dip coating method, casting method, and apply it to the bonding surface of at least one of the films that are superposed with an adhesive. You may

  The environmental temperature at which the injection process is performed and the temperature of the adhesive when injected are not particularly limited. These temperatures can be, for example, about 10 to 35 ° C. (about 25 ° C. or the like).

<Laminating process>
In this step, the polarizing film 10 and the first protective film 20 are bonded together via the adhesive layer formed in the injection step. As shown in FIG. 1, a pair of laminating rolls including a film laminate in which a polarizing film 10 and a first protective film 20 that are continuously conveyed are stacked so that their longitudinal directions (conveying directions) are parallel to each other. The film can be bonded by passing pressure between the films 40 and 40 and applying pressure to the film laminate. The pressure applied to the film laminate by the laminating rolls 40, 40 is, for example, about 0.1 to 4 MPa.

  At this time, in the present invention, the adhesive layer (that is, the adhesive constituting the adhesive layer) when the polarizing film 10 and the first protective film 20 are bonded (when the bonding rolls 40, 40 pass). The viscosity is preferably 50 cP or less. By setting the viscosity of the adhesive layer at the time of laminating the film to 50 cP or less, the excess adhesive easily moves when pressure is applied, and therefore the excess adhesive can be efficiently sucked in the suction step.

  On the other hand, if the viscosity of the adhesive layer is too low, the injected adhesive is likely to leak from the film during bonding. Therefore, the viscosity of the adhesive layer at the time of laminating the film is preferably 1 cP or more, and more preferably 3 cP or more.

  The passing speed (conveying speed) of the polarizing film 10 and the first protective film 20 when passing the pair of bonding rolls 40, 40 is not particularly limited, and can be set to 10 m / min or more, for example. If the passing speed is high, it becomes difficult to adjust the suction speed in the suction step. Therefore, the passing speed is preferably 40 m / min or less.

<Suction process>
FIG. 3 shows a top perspective view in the vicinity of the pair of bonding rolls 40, 40 in the manufacturing method and the manufacturing apparatus shown in FIG. As shown in FIG. 3, suction nozzles (suction means) 90 for sucking the adhesive are provided near both ends of the position where pressure is applied to the film laminate by the pair of laminating rolls 40, 40. In this step, the suction nozzle 90 sucks excess adhesive near the widthwise ends of the film laminate. In the laminating step, when pressure is applied to the film laminate, the pressure is also applied to the adhesive agent interposed between the polarizing film 10 and the first protective film 20, and a part of the film laminate in the width direction. Move toward both ends. Excess adhesive near the both ends in the width direction easily leaks from the ends of the laminated film in a later step, and if the adhesive leaks, the laminated film and the manufacturing apparatus are contaminated. In the present invention, the suction step can suck the excess adhesive that has moved in the widthwise both end directions due to the pressure applied in the bonding step, so that the contamination of the film laminate or the manufacturing apparatus due to the adhesive can be suppressed. can do.

  In FIG. 3, the suction nozzle 90 is provided with a pair of bonding rolls 40, 40 in order to efficiently suck the excess adhesive that moves in the width direction both ends of the film laminate by the pressure applied by the bonding rolls 40, 40. It is provided on a straight line (hereinafter referred to as “intersecting straight line”) where the planes including the respective rotation axes of the compound rolls 40 and 40 and the film laminate intersect. However, the arrangement position of the suction nozzle 90 is not limited to the intersection line and may be in the vicinity of the intersection line. The pressure applied to the film laminate by the pair of bonding rolls 40, 40 is maximized on the intersecting straight line, but even in the vicinity thereof, the pressure may vary depending on the diameter, hardness, pressing pressure, etc. of the bonding rolls 40, 40. This is because, although the range is different, pressure is applied to the film laminate, and excess adhesive moves due to the pressure. The vicinity of the intersecting straight line where the suction nozzle 90 is arranged is, for example, in the range of 10 mm upstream from the intersecting straight line and 10 mm downstream from the intersecting straight line. It is preferably in the range of 10 mm from the intersecting straight line to the downstream side of the intersecting straight line, more preferably in the range of 8 mm from the intersecting straight line to the downstream side of the intersecting straight line, and further preferably in the range of 2 mm from the intersecting straight line. In addition, in order to further reduce the chance that the excess adhesive that has moved in the width direction both ends of the film laminate due to the laminating step leaks from the end of the film laminate, the position where the suction nozzle 90 is provided is set at a position where the suction nozzle 90 is provided as a pair. It is preferable that the pressure applied to the film laminate by the compound rolls 40, 40 is closer to the intersecting straight line at which the pressure is maximized.

  The diameter of the bonding rolls 40, 40 is preferably 100 mm or more and 500 mm or less, and more preferably 200 mm or more and 400 mm or less in order to make the pressure applied to the film laminate uniform and improve workability in maintenance work and the like. It is more preferable that there is. Further, in order to make the pressure applied to the film laminate uniform and obtain good durability, the hardness of the bonding roll is preferably 60 to 95 °, and more preferably 70 to 95 °. preferable. The hardness of the laminating roll can be measured with a type A durometer hardness tester specified in JIS K6253.

  The arrangement position of the suction port of the suction nozzle 90 is preferably variable, and the position of the suction port of the suction nozzle 90 is appropriately set according to the type and viscosity of the adhesive and the hardness of the polarizing film 10 and the first protective film 20. It is preferable to adjust. The suction port of the suction nozzle 90 can be variably configured by a three-dimensional position adjusting mechanism. Further, it is preferable that the tip of the suction nozzle 90 has a suction port for sucking the adhesive and a diluent supply port for supplying a liquid such as water for diluting the adhesive. It is preferable that the diluent is supplied from the diluent supply port when the adhesive is sucked from the suction port of the suction nozzle 90. By carrying out in this way, the diluted adhesive is sucked from the suction port, and it is possible to prevent the suction port from being clogged with the adhesive.

  FIG. 4 is a diagram schematically showing an example of the configuration of the tip of the suction nozzle 90. FIG. 4A shows a configuration in which a suction port 91 for sucking the adhesive and a diluent supply port 92 are arranged side by side in the lateral direction at the tip of the suction nozzle 90, and FIG. Shows a structure in which a suction port 91 for sucking the adhesive is provided at the tip of the suction nozzle 90, and a diluent supply port 92 is provided in the upper part near the center thereof. The thickness of the tip of the suction nozzle 90 is preferably 5 mm or less from the viewpoint of easy insertion between the polarizing film 10 and the first protective film 20.

  In FIG. 3, the suction port of the suction nozzle 90 is arranged so as to be inserted between the polarizing film 10 and the first protective film 20, but the suction port of the suction nozzle 90 coincides with the end of the laminated optical film. It may be arranged at the position or outside thereof. In addition, from the viewpoint of efficiently sucking the excess adhesive, it is preferable that the suction port of the suction nozzle 90 is inserted between the polarizing film 10 and the first protective film 20.

  From the viewpoint of inserting the suction port of the suction nozzle 90 between the polarizing film 10 and the first protective film 20, the width of the polarizing film 10 and the first protective film is longer than the surface length of the pair of bonding rolls 40, 40. It is preferable that the pair of laminating rolls 40, 40 have portions not in contact with the laminating rolls 40 at both widthwise ends. The length in the width direction of the portion not in contact with the pair of bonding rolls 40, 40 is preferably 5 mm or more and 100 mm or less at one end, and more preferably 10 mm or more and 50 mm or less. Since the length in the width direction of the non-contact portion is 5 mm or more, when the suction port of the suction nozzle 90 is inserted between the polarizing film 10 and the first protective film 20, the polarizing film 10 and the first protective film 20. It is possible to prevent the end portion from sharply bending due to the insertion of the suction port of the suction nozzle 90, and it is possible to maintain the transportability of the laminated optical film. On the other hand, when the length of the non-contacting portion in the width direction is 100 mm or less, it is possible to prevent the non-contacting portion from being deformed due to its own weight or the like, and maintain the transportability of the laminated optical film. A preferable arrangement position of the suction nozzle 90 will be described later in detail with reference to FIGS.

<Curing process>
This step is a step of curing or drying the adhesive layer of the laminate of the polarizing film 10 and the first protective film 20 that are bonded together via the adhesive layer. When the adhesive layer is made of a water-based adhesive, the water-based adhesive can be dried using the drying device 50 as shown in FIG. The drying method in the drying device 50 is not particularly limited, and a hot air dryer, an infrared heater or the like can be used.

  The drying temperature is preferably 30 to 95 ° C. If the temperature is lower than 30 ° C, the adhesive may not be dried sufficiently. If the drying temperature exceeds 95 ° C, the polarizing performance of the polarizing film 10 may be deteriorated by heat. The drying time can be set to about 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, more preferably 150 to 600 seconds.

  When the adhesive is an active energy ray-curable adhesive, the adhesive layer can be cured by irradiating with active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays. When the said laminated body consists of the polarizing film 10 and the 1st protective film 20, and does not contain the 3rd film (the protective film laminated | stacked on the other surface of the polarizing film 10), an active energy ray is the 1st protective film 20 side. The irradiation may be performed from the side or from the polarizing film 10 side, but preferably from the first protective film 20 side.

  The active energy rays may be visible rays, ultraviolet rays, X-rays, electron rays, etc., but they are easy to handle, easy to prepare an active energy ray-curable adhesive and its stability, and its curing performance. From the viewpoint of, ultraviolet rays are preferably used. The light source of the active energy ray is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp. Etc. can be preferably used.

The light irradiation intensity to the adhesive layer made of the ultraviolet curable adhesive is determined for each composition of the adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is not limited. It is preferably 0.1 to 100 mW / cm ² . When the light irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when the light irradiation intensity is 100 mW / cm ² or less, adhesion due to heat radiated from the light source and heat generated when the adhesive is cured Less likely to cause yellowing of the agent and deterioration of the polarizing film. The light irradiation time to the adhesive layer is also controlled for each composition of the adhesive and is not particularly limited, but the integrated light amount represented by the product of the light irradiation intensity and the irradiation time is 10 to 5000 mJ / It is preferably set to be m ² . By integrated light quantity is 10 mJ / m ² or more to generate a sufficient amount of the active species derived from the polymerization initiator can proceed more reliably the curing reaction, also, that at 5000 mJ / m ² or less, Irradiation time does not become too long, and good productivity can be maintained.

  When the adhesive layer is cured by irradiating with active energy rays, by irradiating the laminated body with the active energy rays in a state of being in close contact with the convex curved surface, it is possible to suppress wrinkles and curls that may occur in the obtained polarizing plate. An outer peripheral surface of a roll such as a guide roll or a cooling roll can be preferably used as the convex curved surface. The temperature of the cooling roll is, for example, 10 to 30 ° C, preferably 15 to 25 ° C.

  The polarizing plate obtained as described above is usually sequentially wound into a film roll by a winding device (not shown).

  Next, using FIG. 2, the first protective film 20 (first surface film) is attached to one surface of the polarizing film 10, and the second protective film 21 (second surface film) is attached to the other surface. A method for manufacturing a polarizing plate (laminated optical film) by laminating three sheets to be laminated will be described.

  In the injection step, an injection device 30 is used to inject an adhesive between the polarizing film 10 and the first protective film 20 to form an adhesive layer (not shown), and the polarizing film 10 and the second protective film 20. An adhesive layer is injected between the films 21 to form an adhesive layer (not shown). The adhesives that compose these two adhesive layers may be the same or different.

  In the bonding step, the film laminated body including the first protective film 20, the polarizing film 10 and the second protective film 21 is bonded via the adhesive layer formed in the injection step. As shown in FIG. 2, a film stack in which a first protective film 20, a polarizing film 10, and a second protective film 21 that are continuously conveyed are stacked so that their longitudinal directions (conveying directions) are parallel to each other. The film can be bonded by passing the body between the pair of bonding rolls 40, 40 and applying pressure to the film laminate. Except for the above description, it is as described in the manufacturing method of FIG.

<Position of suction nozzle>
5 to 7 are diagrams showing an example of the positional relationship between the laminated optical film and the suction port of the suction nozzle in the bonding step of the present invention. In FIG. 5, the width of the first surface film 71 and the second surface film 72 is longer than the surface length of the pair of bonding rolls 40, 40, and the suction port of the suction nozzle 90 has the first surface film 71 and the second surface. The form inserted in the space between the films 72 is shown.

  FIG. 5 (a) shows a case of two sheets of the first surface film 71 and the second surface film 72 being bonded together via the adhesive layer 81. 5 (b) and 5 (c) show a first surface film 71, a second surface film 72, and an inner film 101 arranged between them, with adhesive layers 81 and 82 interposed therebetween. The case where three sheets are pasted together is shown. In FIG. 5B, the width of the inner film 101 is substantially the same as the width of the first surface film 71 and the second surface film 72, and the space between the first surface film 71 and the second surface film 72 is further inside. It is divided by the film 101, and the suction port of the suction nozzle 90 corresponding to each adhesive layer is inserted into the divided space. In FIG. 5C, the width of the inner film 101 is shorter than the widths of the first surface film 71 and the second surface film 72, and the suction nozzle 90 commonly used for sucking the two adhesive layers 81 and 82. The suction port is inserted in the space between the first surface film 71 and the second surface film 72.

  FIG. 5D shows a first surface film 71, a second surface film 72, and three inner films 101, 102, 103 arranged between them, and adhesive layers 81, 82, 83, 84. The case of 5 sheets pasted together via is shown. In FIG. 5D, the width of the three inner films 101, 102, 103 is shorter than the width of the first surface film 71 and the second surface film 72, and the four adhesive layers 81, 82, 83, 84 are sucked. The suction port of the suction nozzle 90 that is commonly used in the above is inserted into the space between the first surface film 71 and the second surface film 72.

  In FIG. 5, a space in which the sucked adhesive moves is formed between the first surface film 71 and the second surface film 72 (including a case where the space is further divided by the inner film). Since the suction port of the suction nozzle 90 is also inserted in the same space, the adhesive can be efficiently sucked by the suction nozzle 90, and high suction efficiency and prevention of leakage of the adhesive are realized. be able to. Further, even if the adhesive that has not been sucked by the suction nozzle 90 is present in the vicinity of the suction port, there is a distance from the suction port to the surface of the laminated optical film or the pair of bonding rolls 40. It is possible to suppress the occurrence of contamination of the laminated optical film and the manufacturing apparatus as a cause. In the case of FIGS. 5 (a) and 5 (b), the space in which the sucked adhesive moves can be more limited as compared with the case of FIGS. 5 (c) and 5 (d). Since the suction port of the nozzle 90 is also inserted in the more limited space, the suction nozzle 90 can suck the adhesive more efficiently. However, when the number of suction nozzles is large, it is not possible to install all the suction nozzles at the positions where the adhesive can be sucked efficiently due to space restrictions, and the adhesive can be sucked efficiently. Since it becomes difficult, it is preferable that the number of suction nozzles is 2 or less at one end. Therefore, when the number of adhesive layers exceeds 3, as illustrated in FIGS. 5C and 5D, it is possible to install a suction nozzle that is commonly used for sucking a plurality of adhesive layers. preferable.

  From the viewpoint of inserting the suction port of the suction nozzle 90 into the space formed between the first surface film 71 and the second surface film 72, the width of the first surface film 71 and the second surface film 72 is a It is preferable to have a portion, which is longer than the surface length of the rolls 40, 40 and does not come into contact with the pair of bonding rolls 40, 40, at both widthwise end portions. The length in the width direction of the portion not in contact with the pair of bonding rolls 40, 40 is preferably 5 mm or more and 100 mm or less at one end, and more preferably 10 mm or more and 50 mm or less. Since the length in the width direction of the non-contact portion is 5 mm or more, when the suction port of the suction nozzle 90 is inserted between the first surface film 71 and the second surface film 72, the first surface film 71 and the first surface film 71 (2) It is possible to prevent the end portion of the front surface film 72 from being sharply bent by inserting the suction port of the suction nozzle 90, and it is possible to maintain the transportability of the laminated optical film. On the other hand, when the length of the non-contacting portion in the width direction is 100 mm or less, it is possible to prevent the non-contacting portion from being deformed due to its own weight or the like, and maintain the transportability of the laminated optical film.

  6, the width of the first surface film 71 and the second surface film 72 is longer than the surface length of the pair of bonding rolls 40, 40, and the suction port of the suction nozzle 90 has the first surface film 71 and the second surface. The form arrange | positioned in the position which substantially corresponds to the end surface of the film 72 is shown. FIG. 6A shows a case of two sheets in which the first surface film 71 and the second surface film 72 are attached via the adhesive layer 81. 6 (b) and 6 (c) show a first surface film 71, a second surface film 72, and a single inner film 101 arranged between them, with adhesive layers 81 and 82 interposed therebetween. The case where three sheets are pasted together is shown. In FIG. 6B, the width of the inner film 101 is substantially equal to the widths of the first surface film 71 and the second surface film 72, and the space between the first surface film 71 and the second surface film 72 is further inside. The suction nozzle 90 is arranged so as to be divided by the film 101 and correspond to each adhesive layer. In FIG. 6C, the width of the inner film 101 is shorter than the width of the first surface film 71 and the second surface film 72, and the suction nozzle 90 commonly used for sucking the two adhesive layers 81 and 82 is It is arranged.

  In FIG. 6, a space in which the sucked adhesive moves is a space formed between the first surface film 71 and the second surface film 72 (including a case where the space is further divided by the inner film). However, the suction nozzle 90 can efficiently suck the adhesive, and high suction efficiency and prevention of leakage of the adhesive can be realized. Further, even if the adhesive that has not been sucked by the suction nozzle 90 exists near the suction port, since there is a distance from the suction port to the pair of bonding rolls 40, such an adhesive causes a problem in the manufacturing apparatus. It is possible to suppress the occurrence of contamination.

  In FIG. 7, the width of the first surface film 71 and the second surface film 72 is substantially the same as the surface length of the pair of bonding rolls 40, 40, and the suction port of the suction nozzle 90 has the first surface film 71 and the first surface film 71. 2 shows a mode in which it is arranged at a position that substantially coincides with the end surface of the front surface film 72. FIG. 7A shows a case of two sheets of the first surface film 71 and the second surface film 72 that are bonded together via the adhesive layer 81. 7 (b) and 7 (c) show a first surface film 71, a second surface film 72, and an inner film 101 arranged between them, with adhesive layers 81 and 82 interposed therebetween. The case where three sheets are pasted together is shown. In FIG. 7B, the width of the inner film 101 is substantially the same as the width of the first surface film 71 and the second surface film 72, and the space between the first surface film 71 and the second surface film 72 is further inside. Suction nozzles 90 that are divided by the film 101 and correspond to the respective adhesive layers are arranged. In FIG. 7C, the width of the inner film 101 is smaller than the width of the first surface film 71 and the second surface film 72, and the suction nozzle 90 commonly used for sucking the two adhesive layers 81 and 82 is It is arranged.

  In FIG. 7, a space in which the sucked adhesive moves is formed between the first surface film 71 and the second surface film 72 (including a case where the space is further divided by the inner film). However, the suction nozzle 90 can efficiently suck the adhesive, and high suction efficiency and prevention of leakage of the adhesive can be realized.

  Note that, as shown in FIG. 5, FIG. 6 shows the case where the suction port of the suction nozzle 90 is inserted into the space formed between the first surface film 71 and the second surface film 72. As described above, the adhesive can be sucked more efficiently than in the case where the suction port of the suction nozzle 90 is arranged at a position that substantially coincides with the end faces of the first surface film 71 and the second surface film, which is preferable. . The mechanism that causes a difference in suction efficiency between the two will be considered with reference to FIGS. 8 and 9.

  8A and 8B, in the bonding step of bonding two sheets, the suction port of the suction nozzle 90 is inserted into the space formed between the first surface film 71 and the second surface film 72. The case is shown. 9 (a) and 9 (b), in the bonding step of bonding two sheets, the suction port of the suction nozzle 90 is arranged at a position substantially coincident with the end faces of the first surface film 71 and the second surface film 72. Indicates the case. The arrow A shown in FIGS. 8A and 9A indicates the moving direction of the excess adhesive when pressure is applied in the bonding step. An arrow B shown in FIGS. 8B and 9B indicates an expected flow of the ambient atmosphere caused by suction from the suction port of the suction nozzle 90. When the suction port of the suction nozzle 90 is inserted into the space formed between the first surface film 71 and the second surface film 72, as shown in FIGS. It can be expected that the excess adhesive that moves in the direction is efficiently sucked by the suction nozzle 90, while the suction port of the suction nozzle 90 substantially coincides with the end faces of the first surface film and the second surface film 72. 9A and 9B, the excess adhesive that moves in the width direction both ends may slightly leak from the periphery of the suction nozzle 90, as shown in FIGS. 9A and 9B. In addition, the suction force of the suction nozzle may reach the suction of the ambient air in addition to the suction of the adhesive agent, and the suction efficiency may not be as high as that shown in FIGS. 8 (a) and 8 (b). Can be expected.

<Polarizing film, protective film, adhesive>
Next, the polarizing film 10, the protective film (the first protective film 20, the second protective film 21) and the adhesive will be described.

(1) Polarizing Film The polarizing film 10 shown in FIGS. 1 and 2 may be a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented, and a uniaxially stretched polyvinyl alcohol-based resin film may have two colors. Those in which the sex dye is adsorbed and oriented are preferably used.

  As the polyvinyl alcohol-based resin forming the polyvinyl alcohol-based resin film, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The degree of saponification of the polyvinyl alcohol resin can be in the range of 80.0 to 100.0 mol%, preferably 90.0 to 100.0 mol%, more preferably 94.0. It is in the range of 100.0 mol%. When the saponification degree is less than 80.0 mol%, the water resistance and the wet heat resistance of the obtained single-sided protective polarizing plate are deteriorated.

The saponification degree is a unit ratio (mol%) of a ratio of acetic acid groups (acetoxy groups: —OCOCH ₃ ) contained in a polyvinyl acetate-based resin, which is a raw material of a polyvinyl alcohol-based resin, to hydroxyl groups in the saponification step. This is represented by the following formula:
Degree of saponification (mol%) = 100 × (number of hydroxyl groups) / (number of hydroxyl groups + number of acetic acid groups)
Is defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.

  The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 10000, more preferably 1500 to 8000, and further preferably 2000 to 5000. The average degree of polymerization of the polyvinyl alcohol-based resin can also be determined according to JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain preferable polarization performance, and if it exceeds 10,000, the solubility in a solvent is deteriorated, and it becomes difficult to form a polyvinyl alcohol-based resin film.

  The dichroic dye contained (adsorption orientation) in the polarizing film 10 can be iodine or a dichroic organic dye. Specific examples of the dichroic organic dye include red BR, red LR, red R, pink LB, rubin BL, Bordeaux GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Includes Sky Blue, Direct First Orange S, and First Black. The dichroic dyes may be used alone or in combination of two or more.

  The polarizing film 10 comprises a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; It can be manufactured through a step of treating the alcohol-based resin film with a boric acid aqueous solution; and a step of washing with water after the treatment with the boric acid aqueous solution.

  The polyvinyl alcohol resin film is a film formed from the above-mentioned polyvinyl alcohol resin. The film forming method is not particularly limited, and a known method such as a melt extrusion method or a solvent casting method can be adopted. The thickness of the polyvinyl alcohol-based resin film is, for example, about 10 to 150 μm.

  The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before the dyeing of the dichroic dye, at the same time as the dyeing, or after the dyeing. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed at these plural stages.

  In uniaxial stretching, stretching may be performed uniaxially between rolls having different peripheral speeds, or uniaxial stretching may be performed using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the atmosphere, or wet stretching in which a polyvinyl alcohol-based resin film is swollen using a solvent. The stretching ratio is usually about 3 to 8 times.

  As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution (dyeing solution) containing the dichroic dye is adopted. The polyvinyl alcohol-based resin film is preferably subjected to a dipping treatment (swelling treatment) in water before the dyeing treatment.

  When iodine is used as the dichroic dye, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide and dyeing is usually employed. The content of iodine in this dyeing aqueous solution is usually about 0.003 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.1 to 20 parts by weight per 100 parts by weight of water. The temperature of the dyeing aqueous solution is usually about 20 to 40 ° C. The immersion time (dyeing time) in the dyeing aqueous solution is usually about 20 to 600 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic pigment, a method of immersing the polyvinyl alcohol resin film in a dyeing aqueous solution containing a water-soluble dichroic organic dye and dyeing is usually employed. The content of the dichroic organic dye in the dyeing aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight, per 100 parts by weight of water. This dyeing aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dyeing aqueous solution is usually about 20 to 80 ° C. The immersion time (dyeing time) in the dyeing aqueous solution is usually about 20 to 600 seconds.

  The boric acid treatment after dyeing with the dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 20 parts by weight, preferably about 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 10 to 600 seconds, preferably about 60 to 420 seconds, more preferably about 90 to 300 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

  The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the polyvinyl alcohol resin film treated with boric acid in water. The temperature of water in the water washing treatment is usually about 1 to 40 ° C. The immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain the polarizing film 10. The drying treatment includes various methods such as a method of blowing hot air, a method of contacting with a hot roll, and a method of heating with an IR heater, and any of them can be preferably used. The method of drying by contacting with a hot roll is preferable in that the drying time can be shortened because the drying efficiency is improved, and the film can be widened by suppressing the shrinkage in the width direction. is there. The drying temperature in the drying step means the atmospheric temperature in the drying furnace in the case of a drying equipment such as a method of blowing hot air or a drying furnace such as an IR heater, and contact-type drying such as a heat roll. In the case of equipment, it means the surface temperature of the thermo roll.

  The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 40 to 80 ° C. The drying treatment time is usually about 30 to 600 seconds, preferably 80 to 300 seconds. The thickness of the polarizing film 10 is usually about 2 to 40 μm.

  By the drying treatment, the moisture content of the polarizing film 10 is reduced to a practical level. The water content thereof is usually adjusted to 5 to 45% by weight, more preferably 7 to 40% by weight. If it is less than 5% by weight, the flexibility of the polarizing film 10 may be lost and the polarizing film 10 may be damaged or broken after drying. If it is more than 45% by weight, the adhesion with the protective film may be reduced. Is not sufficiently exhibited, and problems such as poor appearance and film breakage in the line and contaminating the process are likely to occur.

  The film width of the long polarizing film 10 is not particularly limited and can be usually about 0.2 to 2 m.

(2) Protective film The protective film (first protective film 20 or second protective film 21) used as the first surface film or the second surface film is laminated on the polarizing film 10 to protect the polarizing film 10. Is at least responsible. The protective film is not particularly limited as long as it has translucency (preferably transparency), and may be a thermoplastic resin film or a film made of a glass material. Examples of the film made of a glass material include glass films described in JP 2012-247785 A, WO 12/090693 A, JP 08-283041 A, and the like.

  Specific examples of the thermoplastic resin forming the protective film include, for example, polyolefin resins such as chain polyolefin resins (polypropylene resin etc.) and cyclic polyolefin resins (norbornene resin etc.); cellulose triacetate, cellulose diacetate. Such as a cellulose ester resin; a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate; a polycarbonate resin; a (meth) acrylic resin such as a polymethyl methacrylate resin; or a mixture thereof. It may be a transparent resin film made of a copolymer or the like.

  Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resin and polypropylene resin, and copolymers of two or more chain olefins. More specific examples include polypropylene resin (polypropylene resin which is a propylene homopolymer or copolymer mainly containing propylene), polyethylene resin (polyethylene resin which is an ethylene homopolymer or ethylene). And a copolymer).

  Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerized unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137 and the like. Resins. Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or their derivatives, and their hydrides. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as the cyclic olefin are preferably used.

  The cellulose ester-based resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of the hydroxyl groups are modified with other substituents can also be used. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable.

  The polyester resin is a resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or its derivative and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. A divalent diol can be used as the polyhydric alcohol, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

  A polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin may be a resin called modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolycarbonate having improved wavelength dependence, or the like.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of the (meth) acrylic resin include, for example, poly (meth) acrylic acid ester such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylic acid. Ester copolymer; Methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer; Methyl (meth) acrylate-styrene copolymer (MS resin etc.); Methyl methacrylate and alicyclic hydrocarbon group It includes a copolymer with a compound having (for example, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.). Preferably, a polymer containing poly (meth) acrylic acid C _1-6 alkyl ester as a main component such as methyl poly (meth) acrylate is used, and more preferably, methyl methacrylate is a main component (50 to 100). % By weight, preferably 70 to 100% by weight) is used.

  The protective film can contain various additives as needed. Specific examples of additives include optical brighteners, dispersants, surfactants, heat stabilizers, light stabilizers, ultraviolet absorbers, infrared absorbers, antistatic agents, antioxidants, lubricants, organic dyes, pigments. , Inorganic dyes and the like.

  The thickness of the protective film is usually about 2 to 300 μm, preferably 10 μm or more, preferably 200 μm or less, more preferably 150 μm or less, and further preferably 100 μm or less. Although the film width of the long protective film is not particularly limited, in the laminating step, a space is formed between the protective film and the polarizing film at both ends in the width direction of the film laminate, and a suction nozzle sucks in the space. In the form in which the mouth is inserted, it is preferable that the protective film and the polarizing film have substantially the same width.

  The protective film may be obtained by subjecting the thermoplastic resin film to a stretching treatment. An arbitrary retardation value can be given by stretching. The protective film having a predetermined retardation property is also called an optical compensation film or a retardation film. Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include the machine flow direction (MD) of the unstretched film, the direction (TD) orthogonal thereto, and the direction oblique to the machine flow direction (MD). The biaxial stretching may be simultaneous biaxial stretching in which two stretching directions are simultaneously performed, or sequential biaxial stretching in which the stretching is performed in a predetermined direction and then in another direction.

  The protective film may have a surface treatment layer such as a hard coat layer, an antiglare layer, an antistatic layer, an antireflection layer, or an antifouling layer on the surface opposite to the surface laminated with the polarizing film 10. Good.

  Further, in order to improve the adhesiveness with the polarizing film 10, it is preferable to perform a surface activation treatment on the bonding surface of the protective film prior to the injection of the adhesive. Specific examples of the surface activation treatment include plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment (immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide). Instead of the bonding surface of the protective film, or together with the bonding surface of the protective film, the bonding surface of the polarizing film 10 may be subjected to surface activation treatment.

  In the example shown in FIG. 2, the first protective film 20 and the second protective film 21 may be the same kind of film or different kinds of films.

(3) Adhesive Examples of the adhesive used in the present invention include a water-based adhesive and an active energy ray-curable adhesive. Usually, the amount of adhesive injected in the injection process is larger when using a water-based adhesive than when using an active energy ray-curable adhesive, and the problem of adhesive leakage from the end is more likely to occur. Therefore, the effect of the present invention that the leakage of the adhesive can be suppressed is more remarkable when the water-based adhesive is used.

  The water-based adhesive is one in which the adhesive component is dissolved in water or dispersed in water. The water-based adhesive that is preferably used is, for example, an adhesive composition that uses a polyvinyl alcohol-based resin or a urethane resin as a main component. When the adhesive layer 31 is formed of a water-based adhesive, its thickness is usually 1 μm or less.

  When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin includes partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and methylol group. A modified polyvinyl alcohol-based resin such as modified polyvinyl alcohol or amino group-modified polyvinyl alcohol may be used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponification of polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymerization of vinyl acetate and other monomers copolymerizable with it. It may be a polyvinyl alcohol-based copolymer obtained by saponifying the combined product.

  A water-based adhesive containing a polyvinyl alcohol-based resin as an adhesive component is usually an aqueous solution of polyvinyl alcohol-based resin. The concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.

  The adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin contains a curable component such as a polyhydric aldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal, a glyoxal derivative, and a water-soluble epoxy resin in order to improve the adhesiveness. It is preferable to add a crosslinking agent. As the water-soluble epoxy resin, for example, a polyamidoamine obtained by reacting a polyalkylenepolyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid, a polyamidepolyamine epoxy resin obtained by reacting epichlorohydrin Can be preferably used. Commercially available products of such polyamide polyamine epoxy resin include "SUMIREZ RESIN 650" (manufactured by Taoka Chemical Industry Co., Ltd.), "SUMIREZ RESIN 675" (manufactured by Taoka Chemical Industry Co., Ltd.), "WS-525" (Japan PMC Co., Ltd. etc. are mentioned. The addition amount of these curable components and cross-linking agents (when the curable components and cross-linking agents are added together, the total amount thereof) is usually 1 to 100 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. It is 1 to 50 parts by weight. When the addition amount of the curable component or the cross-linking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesiveness tends to be small, and the curable component or When the addition amount of the crosslinking agent exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the adhesive layer tends to become brittle.

  When a urethane resin is used as the main component of the adhesive, a mixture of a polyester type ionomer type urethane resin and a compound having a glycidyloxy group can be given as an example of a suitable adhesive composition. The polyester type ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced therein. Such an ionomer type urethane resin is suitable as a water-based adhesive because it directly emulsifies in water to form an emulsion without using an emulsifier.

  The active energy ray curable adhesive is an adhesive that can be cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. As the active energy ray-curable adhesive, an active energy ray-curable adhesive having an epoxy compound that is cured by cationic polymerization as a curable component can be more preferably used, and more preferably such an epoxy compound is a curable component. It is a UV curable adhesive. The epoxy-based compound as used herein means a compound having an average of 1 or more, and preferably 2 or more epoxy groups in the molecule. The epoxy compounds may be used alone or in combination of two or more.

  An example of an epoxy compound that can be suitably used is a hydrogenated epoxy compound obtained by reacting epichlorohydrin with an alicyclic polyol obtained by performing a hydrogenation reaction on an aromatic ring of an aromatic polyol (oil Glycidyl ether of polyol having cyclic ring); Aliphatic epoxy compound such as polyglycidyl ether of aliphatic polyhydric alcohol or alkylene oxide adduct thereof; One epoxy group bonded to alicyclic ring in the molecule It includes an alicyclic epoxy compound which is an epoxy compound having the above.

  The active energy ray-curable adhesive may further contain a radical-polymerizable (meth) acrylic compound as a curable component. The (meth) acrylic compound is a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and at least two in the molecule. (Meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having a (meth) acryloyloxy group.

  When the active energy ray-curable adhesive contains an epoxy compound that is cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the cationic photopolymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes and the like. When the active energy ray-curable adhesive contains a radical-polymerizable curable component such as a (meth) acrylic compound, it preferably contains a photo-radical polymerization initiator. Examples of the radical photopolymerization initiator include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthones, fluorenones, camphorquinones, benzaldehydes, and anthraquinones.

[Polarizing plate manufacturing process]
A polarizing plate can be produced using the laminated optical film including the polarizing film 10 and the protective film obtained as described above. The laminated optical film may be used as a polarizing plate as it is, or the laminated optical film may be subjected to the following treatment to prepare a polarizing plate.

<Curing process>
After the curing step, curing may be carried out at a temperature of room temperature or higher for at least half a day, usually several days or longer to obtain sufficient adhesive strength (curing step). Such a curing step is typically performed in a state of being rolled up. The preferred curing temperature is in the range of 30 to 50 ° C, more preferably 35 to 45 ° C. If the curing temperature exceeds 50 ° C., so-called “roll tightness” is likely to occur in the roll wound state. The humidity during curing is not particularly limited, but is preferably selected so that the relative humidity is in the range of about 0 to 70% RH. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

<Excision process>
In the above bonding step, when the polarizing film 10 and the protective film have widthwise both ends that do not contact the pair of bonding rolls 40, a cutting step of cutting the portion including the widthwise both ends in this step is performed. May be. At this time, it is preferable to cut the polarizing film 10, the protective film, and the adhesive layer so that the side end surfaces thereof are aligned.

  The excision method is not particularly limited, but for example, a method generally called a slitter can be preferably used. An example of a slitter is a method using a razor blade called a leather blade. Even with the method using the same leather blade, there are hollow cutting that slits in the air without providing a backup guide, and the groove roll method that stabilizes the meandering of the slit by inserting the blade into a grooved roll as a backup guide. is there. In addition, a method of using two circular blades called shear blades to apply slits by applying contact pressure to the lower blades with the upper blade while rotating according to the transport of the film, and blades called shear blades and score blades It is possible to use a method of pressing by pressing it on a quenching roll or the like, and a method of combining two shear blades and slitting while cutting like scissors. Among them, the “groove roll method using a leather blade”, which is a method in which the slit position of the film can be easily changed and the traveling is easily stabilized, is preferably used.

<Adhesive layer forming step>
After the curing step, a pressure-sensitive adhesive layer forming step of laminating a pressure-sensitive adhesive layer on the outer surface of the protective film of the laminated optical film may be performed to obtain a pressure-sensitive adhesive layer-attached polarizing plate. A polarizing plate can be attached to a liquid crystal cell by using such an adhesive layer.

  The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer may be any conventionally known appropriate pressure-sensitive adhesive, for example, acrylic pressure-sensitive adhesive, urethane pressure-sensitive adhesive, silicone pressure-sensitive adhesive, polyester pressure-sensitive adhesive, polyamide pressure-sensitive adhesive, Examples thereof include polyether adhesives, fluorine adhesives, rubber adhesives and the like. Above all, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by using a pressure-sensitive adhesive in the form of, for example, an organic solvent solution, coating it on a protective film with a die coater, a gravure coater, or the like and drying it, or performing a release treatment. It can also be provided by a method of transferring a sheet-like pressure-sensitive adhesive formed on a formed plastic film (referred to as a separate film) onto a protective film. Whichever method is used, it is preferable that a separate film is attached to the surface of the pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer can be, for example, 2 to 40 μm.

  10 Polarizing film, 20 1st protective film, 21 2nd protective film, 30 Injection device, 40 Laminating roll, 50 Drying device, 71 1st surface film, 72 2nd surface film, 81, 82, 83, 84 Adhesive Layer, 101, 102, 103 Inner film, 90 Suction nozzle (suction means), 91 Suction port, 92 Diluent supply port.

Claims (6)

A method for producing a laminated optical film having at least two laminated films, including a first surface film and a second surface film,
A film having the first surface film forming one surface, the second surface film forming the other surface, and an adhesive layer provided between the first surface film and the second surface film. Lamination, passing between a pair of rolls, a laminating step of applying pressure to the film laminate,
And a suction step of sucking excess adhesive that moves toward both widthwise ends of the film laminate by the pressure.   The method for manufacturing a laminated optical film according to claim 1, wherein, in the suction step, the position of the suction port of the suction unit that sucks the adhesive is variable.   The width of the first surface film and the second surface film is longer than the surface length of the pair of rolls, and has a portion that does not come into contact with the pair of rolls at both ends in the width direction in the laminating step. Item 3. A method for producing a laminated optical film according to Item 1 or 2.   In the suction step, a suction port of a suction unit that sucks the adhesive is inserted in a space between the first surface film and the second surface film at both ends in the width direction of the film laminate. The method for producing a laminated optical film according to claim 3. The laminated optical film has at least one inner film laminated between the first surface film and the second surface film,
The width of the first surface film and the second surface film is longer than that of the inner film, and in the laminating step, portions having no inner film are provided at both ends in the width direction. The method for producing a laminated optical film according to any one of 1.   The method for manufacturing a laminated optical film according to claim 1, wherein in the suction step, a liquid for diluting the sucked adhesive is supplied and the diluted adhesive is sucked.

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