Method and apparatus for manufacturing polarizing plates

Abstract

To provide a method for manufacturing a polarizer that facilitates detection of a decrease in a suction volume of liquid adhesive.SOLUTION: A method for manufacturing a polarizer includes: a process of passing a long film laminate 40 having a polarizer film, an optical film, and a liquid adhesive layer between the polarizer film and the optical film between a pair of rolls 52, 54 to apply pressure to the film laminate 40; a suction process to suction excess liquid adhesive AD between the polarizer film 10 and the optical films 20, 30 with a suction nozzle 82; a process of supplying diluent liquid with diluent liquid supply nozzles 84, 86 to an inside of the suction nozzle 82 and / or to a tip of the suction nozzle 82; and a process for monitoring an internal pressure of the liquid supply nozzles 84, 86 for dilution and / or a flow rate of the liquid flowing through the liquid supply nozzles 84, 86 for dilution.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing a polarizing plate.

Background Art

[0002] Conventionally, it is known to bond a polarizer film, an optical film such as a protective film, and a laminate containing a liquid adhesive between these films by passing the laminate between a pair of bonding rolls.

[0003] In such a bonding method, application of pressure by the bonding rolls causes excess liquid adhesive to move to end portions in the width direction of the laminate. For this reason, bonding is continued while sucking the excess liquid adhesive with a suction nozzle to remove it from the laminate, and a liquid such as water is supplied to the nozzle in order to prevent clogging of the suction nozzle.

Prior Art Literature

Patent Literature

[0004]

Patent Literature 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, even when water or the like is supplied, clogging of part or all of the suction nozzle may occur due to solidification of the liquid adhesive, and moreover, due to suction of foreign matter, suction of the polarizer film or the optical film, or the like, the suction amount of the excess liquid adhesive may be insufficient. If the suction amount of the liquid adhesive is insufficient, the liquid adhesive overflows from between the films, causing process contamination and quality deterioration.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for manufacturing a polarizing plate that can easily detect a decrease in the suction amount of a liquid adhesive.

Means for Solving the Problem

[0007] A method for manufacturing a polarizing plate according to one aspect of the invention includes the steps of passing a long film laminate having a polarizer film, an optical film, and a liquid adhesive layer provided between the polarizer film and the optical film between a pair of rolls and applying pressure to the film laminate, A suction step in which excess liquid adhesive between the polarizer film and the optical film is suctioned using a suction nozzle, A step of supplying a dilution liquid to the inside of the suction nozzle and / or to the tip of the suction nozzle using a dilution liquid supply nozzle, The method includes a step of monitoring the internal pressure of the dilution liquid supply nozzle and / or the flow rate of the liquid flowing through the dilution liquid supply nozzle.

[0008] In the above method, the width of the pair of rolls is narrower than the width of the film laminate. Excess liquid adhesive accumulating at both ends in the width direction of the film laminate can be sucked up with the suction nozzle.

[0009] In the above method, a dilution liquid is supplied to the tip of a single suction nozzle from both an upstream liquid supply nozzle located on the upstream side in the transport direction of the film laminate, and a downstream liquid supply nozzle located on the downstream side in the transport direction of the film laminate. The internal pressure and / or flow rate can be monitored for both the upstream liquid supply nozzle and the downstream liquid supply nozzle.

[0010] A polarizing plate manufacturing apparatus according to one embodiment includes a pair of rolls for applying pressure to a long film laminate having a polarizer film, an optical film, and a liquid adhesive layer provided between the polarizer film and the optical film, A suction nozzle for sucking up excess liquid adhesive between the polarizer film and the optical film, A dilution liquid supply nozzle that supplies a dilution liquid to the inside of the suction nozzle and / or to the tip of the suction nozzle, The system includes a sensor that monitors the internal pressure of the dilution liquid supply nozzle and / or the flow rate of the liquid flowing through the dilution liquid supply nozzle. [Effects of the Invention]

[0011] According to the present invention, a method and apparatus for manufacturing a polarizing plate that makes it easy to detect a decrease in the amount of liquid adhesive absorbed is provided. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a flowchart showing an example of the manufacturing method and apparatus of this embodiment. [Figure 2] Figure 2 is a partial cross-sectional view showing one end of the roll in Figure 1, viewed from above. [Figure 3] Figure 3 is a schematic diagram showing the vicinity of the nozzle assembly in Figure 2, viewed from the opening side. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described with reference to the drawings.

[0014] Figure 1 is a flow diagram showing a method and apparatus for manufacturing a polarizing plate according to one embodiment of the present invention. Figure 2 is a partial cross-sectional view showing one end of the roll 52 in Figure 1 viewed from above. Figure 3 is a schematic diagram of the vicinity of the nozzle assembly 80 in Figure 2 viewed from the opening side.

[0015] The polarizing plate manufacturing method according to this embodiment comprises a pressure application step, a suction step, a dilution liquid supply step, and a monitoring step. The polarizing plate manufacturing apparatus according to this embodiment comprises a pair of rolls 52, 54, a suction nozzle 82, dilution liquid supply nozzles 84, 86, and sensors M1, M2. A detailed description follows below.

[0016] (Pressure application process) In the method for producing a polarizing plate according to the present embodiment, first, a step is performed in which a film laminate 40 having a polarizer film 10, optical films 20 and 30, and a liquid adhesive layer provided between the polarizer film 10 and the optical films 20 and 30 is passed between a pair of rolls 52 and 54 to apply pressure to the film laminate 40.

[0017] (Polarizer film) An example of the polarizer film 10 is a stretched film dyed with a dichroic dye. An example of the dichroic dye is an iodine-based compound such as iodine. An example of the film is a polyvinyl alcohol-based film. The polarizer film may be crosslinked with a crosslinking agent such as boron.

[0018] The polarizer film may contain a cured product of an aligned polymerizable liquid crystal compound and a dichroic dye, wherein the dichroic dye is dispersed and aligned in the cured product of the polymerizable liquid crystal compound. In that case, the polarizer film may include an alignment film.

[0019] The thickness of the polarizer film may be 30 µm or less, and preferably 5 µm or more and 25 µm or less.

[0020] (Optical film) The optical films 20 and 30 are films capable of transmitting light. The optical films 20 and 30 may be the same as or different from each other.

[0021] An example of the optical film is a resin film, and examples of the resin include polyvinyl alcohol-based resins, cellulose-based resins (such as triacetyl cellulose), polyolefin-based resins (such as polypropylene-based resins), cyclic olefin-based resins (such as norbornene-based resins), acrylic resins (such as polymethyl methacrylate-based resins), polyester-based resins (such as polyethylene terephthalate-based resins), and polyimide-based resins (polyimide, polyamideimide), etc.

[0022] The optical film may be a protective film, a phase difference film (such as a λ / 2 phase difference plate or a λ / 4 phase difference plate), and / or a window film. The optical film may also be a laminated film. For example, the optical film may further include a base film, an adhesive layer, a tack layer, a release film (weakly adhered to the tack layer and peeled off from the tack layer when the film laminate is attached to another component), a protective film (strongly adhered to the tack layer and peeled off together with the tack from other films to be protected), and so on.

[0023] There are no limitations on the thickness of the optical film; it can be between 200 and 300 μm.

[0024] There is no limit to the total thickness of the film laminate 40; it can be between 10 and 500 μm.

[0025] There are no particular limitations on the width of the polarizer film 10 and the optical films 20 and 30, and they can be between 500 and 2,500 mm.

[0026] The polarizer film 10 and the optical films 20 and 30 are long films (rolls), and their longitudinal length can be 100 to 100,000 m, or 8,000 m or less.

[0027] In this process, as shown in Figure 1, the polarizer film 10, the optical film 20 guided by the roll 5, and the optical film 30 guided by the roll 7 are stacked. In this embodiment, the polarizer film 10 and the film laminate 40 are conveyed horizontally.

[0028] Liquid adhesive is supplied from a nozzle 70 connected to line L1 to the areas where the polarizer film 10 and the optical film 20 overlap, and to the areas where the polarizer film 10 and the optical film 30 overlap. The amount of liquid adhesive supplied can be set appropriately according to the type and viscosity of the adhesive in the liquid adhesive.

[0029] This forms a film laminate 40 having a polarizer film 10, optical films 20 and 30, and a liquid adhesive layer provided between the polarizer film 10 and the optical films 20 and 30, which is then supplied between a pair of rolls 52 and 54. Between the pair of rolls 52 and 54, pressure is applied to the film laminate 40 in the thickness direction by the rolls. The bonding pressure can be, for example, 0.1 to 4.0 MPa.

[0030] Liquid adhesives may contain an adhesive and, if necessary, a diluent (solvent).

[0031] The adhesive is not particularly limited, and various conventionally known adhesives can be used. For example, polyvinyl alcohol-based adhesives, polyurethane-based adhesives, isocyanate-based adhesives, and adhesives consisting of the polyvinyl alcohol-based adhesive and a water-soluble crosslinking agent such as boric acid, borax, glutaraldehyde, melamine, and oxalic acid can be used. In particular, considering that it provides the best adhesion to the polarizer film 10, it is preferable to use a polyvinyl alcohol-based adhesive.

[0032] The liquid (solvent) used to dilute the liquid adhesive is not particularly limited and may be, for example, water. Furthermore, the liquid adhesive may contain other additives or catalysts such as acids as needed.

[0033] Furthermore, there are no particular limitations on the viscosity of the liquid adhesive, but it is preferably in the range of 1 to 1000 mPa·s, and more preferably in the range of 1 to 100 mPa·s.

[0034] Figure 2 shows a top view of the vicinity of the end of roll 52 in Figure 1. The film laminate 40 is conveyed upward according to the conveying direction A indicated by the arrow in the figure. As described above with respect to Figure 1, liquid adhesive AD is supplied between the polarizer film 10 and the optical film 20, and between the polarizer film 10 and the optical film 30, respectively, just before being sandwiched between the pair of rolls 52 and 54 of the film laminate 40.

[0035] The width of the polarizer film 10 is smaller than the width of the optical films 20 and 30. Similarly, the width (axial length) of the rolls 52 and 54 is smaller than the width of the optical films 20 and 30, leaving unpressed portions (unpressed areas) at both ends of the film laminate 40 in the width direction, where the film laminate 40 is not pressed by the rolls 52 and 54 and the polarizer film 10 is not laminated. The excess liquid adhesive AD is pushed out to the outside of the rolls in the width direction, i.e., to the unpressed areas at both ends of the film laminate 40 in the width direction, as the film laminate 40 is pressed by the rolls 52 and 54, and accumulates in these unpressed areas.

[0036] (Suction process) Next, a suction process is performed in which the excess liquid adhesive AD accumulated in the non-pressed area is sucked up by a suction nozzle 82 provided on the nozzle assembly 80.

[0037] Figure 2 shows a horizontal cross-sectional view of the nozzle assembly 80. The nozzle assembly 80 includes a suction nozzle 82 and a dilution liquid supply nozzle 84.

[0038] The opening 82O of the suction nozzle 82 is located on the roll-side end face 80S of the nozzle assembly 80. The suction nozzle 82 is provided with a line L4 having a suction pump P1. Excess liquid adhesive AD is sucked out from the opening 82O of the suction nozzle 82 and removed from the film laminate 40.

[0039] Figure 3 is an enlarged view of the vicinity of the nozzle assembly 80 in Figure 2, as seen from the nozzle side. The nozzle assembly 80 is located between the upper optical film 20 and the lower optical film 30. Therefore, excess adhesive between the optical film 20 and the optical film 30 is sucked up by the nozzle assembly 80. As shown in Figure 2, the area where the nozzle assembly 80 is located is a non-pressed area in the film laminate 40, that is, an area that is not pressed by the pair of rolls 52, 54 and where the polarizer film 10 does not exist.

[0040] (Dilution liquid supply process) As shown in Figures 2 and 3, the openings 84O and 86O of the dilution liquid supply nozzles 84 and 86 are provided on the roll-side end face 80S of the nozzle assembly 80. Specifically, the openings 84O and 86O are positioned to supply the dilution liquid to the tip 82t of the suction nozzle 82, i.e., the wall forming the opening 82O. In this embodiment, two dilution liquid supply nozzles are provided for one nozzle assembly 80, with the opening 84O of one dilution liquid supply nozzle (downstream liquid supply nozzle) 84 being located downstream of the opening 82O of the suction nozzle 82 in the transport direction A of the film laminate 40, and the opening 86O of the other dilution liquid supply nozzle (upstream liquid supply nozzle) 86 being located upstream of the opening 86O of the suction nozzle 82 in the transport direction A of the film laminate 40.

[0041] There are no particular limitations on the position of the nozzle assembly 80, but it is preferable that it satisfies the following conditions. First, let's explain the position of the end face 80S of the nozzle assembly 80, where the openings 82O ​​and 84O are formed, as shown in Figure 2. The distance G between the end face 80S of the nozzle assembly 80 and the end faces 52S and 54S of the rolls 52 and 54 is preferably 0 to 10 mm.

[0042] Next, we will explain the position of the center of gravity (center) 82G of the opening 82O of the suction nozzle 82 of the nozzle assembly 80, as shown in Figure 3. First, the position of the centroid 82G of the opening 82O of the suction nozzle 82 in the Z direction perpendicular to the plane containing the film laminate 40 will be explained. Using the point RP where the plane P10 containing the central axis 52X of the roll 52 and the central axis 54X of the roll 54 intersects with the film laminate 40 as the reference point (distance 0), and assuming that the direction approaching the central axis 52X of one roll 52 is the +Z coordinate and the direction approaching the central axis 54X of the other roll 54 is the -Z coordinate, the position of the centroid 82G of the opening 82O of the suction nozzle 82 in the Z-axis direction is preferably within ±15 mm, and more preferably within ±5 mm, with respect to the position of Z=0.

[0043] Next, in Figure 3, the position of the center of gravity 82G of the opening 82O of the suction nozzle 82 in the transport direction of the film laminate 40 will be explained. Using the point RP where the plane P10 containing the central axis 52X of the roll 52 and the central axis 54X of the roll 54 intersects with the film laminate 40 as a reference, and taking the direction opposite to the transport direction A of the film laminate 40 as the -Y coordinate, the position of the center of gravity 82G in the Y-axis direction is preferably 0 to -20 mm with respect to the position Y=0.

[0044] As shown in Figure 2, line L2 with pump P2 is connected to diluent supply nozzle 84, and line L3 with pump P3 is provided to diluent supply nozzle 86. Diluent liquid is supplied through lines L2 and L3, respectively. The diluent liquid may be the same as or different from the diluent liquid in the liquid adhesive. A typical diluent liquid is water. The supply rate of the diluent liquid is usually set to an appropriate constant value.

[0045] By supplying dilution liquid from dilution liquid supply nozzles 84 and 86, the liquid at the tip of the suction nozzle 82 is diluted, which can suppress the adhesion of adhesive at the tip of the suction nozzle 82.

[0046] The supplied diluent is drawn in through the suction nozzle 82.

[0047] (Monitoring process) Next, the internal pressure of the dilution liquid supply nozzles 84 and 86, and / or the flow rate of the liquid flowing through the dilution liquid supply nozzles 84 and 86, are monitored by sensors. This monitoring continues while the laminated film is pressed and bonded.

[0048] Sensor M1 is installed on line L2, and sensor M2 is installed on line L3. Sensors M1 and M2 detect the internal pressure and / or flow rate of the fluid over time, respectively.

[0049] If the adhesive solidifies or precipitates inside or at the tip of the suction nozzle 82, or if the suction nozzle 82 sucks up the film, and the amount of liquid adhesive sucked by the suction nozzle 82 decreases, the state of the liquid at the openings of the dilution liquid supply nozzles 84 and 86 changes, causing the outputs (internal pressure, flow rate) of sensors M1 and M2 to change.

[0050] Therefore, by setting thresholds for the outputs of sensors M1 and M2, it is possible to monitor whether the output of sensor M1 fluctuates significantly and issue a warning if it does. When a warning is issued, checking the situation can help prevent major problems such as liquid adhesive overflow.

[0051] The measurements from sensors M1 and M2 can be monitored, for example, by a computer.

[0052] (action) One possible method for monitoring the amount of excess liquid adhesive AD suction is to measure and monitor the pressure or flow rate of the suction nozzle 82. However, the suction nozzle 82 may also draw in gases such as air from the environment in addition to the liquid adhesive AD and diluent liquid, and the measured values ​​of the internal pressure and flow rate can fluctuate significantly due to factors other than blockage. Therefore, even if the pressure or flow rate of the suction nozzle 82 is monitored, it is difficult to accurately grasp the decrease in the amount of liquid adhesive AD suction due to blockage or other reasons.

[0053] In contrast, since no gas enters the dilution liquid supply nozzles 84 and 86, changes in the internal pressure and flow rate of the dilution liquid supply nozzles can be monitored to accurately and quickly recognize changes in the flow state of liquids such as the liquid adhesive AD near the outlet opening of the suction nozzle 82. Therefore, blockage of the suction nozzle 82, a decrease in the amount of liquid adhesive suctioned due to film suction, etc., can be quickly detected.

[0054] The present invention is not limited to the above embodiments and can take various modified forms.

[0055] For example, in Figure 2, two dilution liquid supply nozzles are provided, but either one may be used, and the position and shape of the opening that supplies the dilution liquid to the tip of the suction nozzle may also be in other configurations. Furthermore, the dilution liquid supply nozzle may be configured to supply the dilution liquid inside the suction nozzle.

[0056] Furthermore, in the above embodiment, the transport direction of the polarizer film 10 and the film laminate 40 is horizontal, but the transport direction can be set as appropriate. For example, the transport direction of the polarizer film 10 and the film laminate 40 may be vertical.

[0057] Furthermore, in the above embodiment, the width of the pair of rolls is narrower than the width of the film laminate, but the width of the pair of rolls may be the same as or wider than the width of the film laminate. In this case, excess liquid adhesive accumulates upstream of the lamination rolls of the film laminate, but even in this case, similar effects can be produced by suction with a suction nozzle, supply of dilution liquid with a dilution liquid nozzle, and monitoring of the internal pressure / flow rate of the dilution liquid supply nozzle.

[0058] Furthermore, in the above embodiment, the two optical films 20 and 30 are bonded to the polarizer film simultaneously with a liquid adhesive, but it is also possible to bond only one of the optical films. [Explanation of Symbols]

[0059] 10...Polarizer film, 20,30...Optical film, 40...Film laminate, 52,54...Roll, 82...Suction nozzle, 84...Dilution liquid supply nozzle (downstream liquid supply nozzle), 86...Dilution liquid supply nozzle (upstream liquid supply nozzle), AD...Liquid adhesive, M1,M2...Sensor.

Claims

1. A process of passing a long film laminate having a polarizer film, an optical film, and a liquid adhesive layer provided between the polarizer film and the optical film between a pair of rolls and applying pressure to the film laminate, A suction step in which excess liquid adhesive between the polarizer film and the optical film is suctioned using a suction nozzle, A step of supplying a dilution liquid to the inside of the suction nozzle and / or to the tip of the suction nozzle using a dilution liquid supply nozzle, A method for manufacturing a polarizing plate, comprising the step of monitoring the internal pressure of the dilution liquid supply nozzle and / or the flow rate of the liquid flowing through the dilution liquid supply nozzle to detect a decrease in the amount of liquid adhesive aspirated by the suction nozzle.

2. The width of the pair of rolls is narrower than the width of the film laminate. The method for manufacturing a polarizing plate according to claim 1, wherein excess liquid adhesive accumulating at both ends in the width direction of the film laminate is sucked up with the suction nozzle.

3. For each suction nozzle, a dilution liquid is supplied to the tip of the suction nozzle from both an upstream liquid supply nozzle located on the upstream side in the transport direction of the film laminate, and a downstream liquid supply nozzle located on the downstream side in the transport direction of the film laminate. A method for manufacturing a polarizing plate according to claim 1 or 2, wherein the internal pressure and / or flow rate are monitored for both the upstream liquid supply nozzle and the downstream liquid supply nozzle.

4. A pair of rolls for applying pressure to a long film laminate having a polarizer film, an optical film, and a liquid adhesive layer provided between the polarizer film and the optical film, A suction nozzle for sucking up excess liquid adhesive between the polarizer film and the optical film, A dilution liquid supply nozzle that supplies a dilution liquid to the inside of the suction nozzle and / or to the tip of the suction nozzle, A sensor that monitors the internal pressure of the dilution liquid supply nozzle and / or the flow rate of the liquid flowing through the dilution liquid supply nozzle, A polarizing plate manufacturing apparatus comprising means for detecting a decrease in the amount of liquid adhesive aspirated by the suction nozzle based on the measurement value of the sensor.

5. A pair of rolls for applying pressure to a long film laminate having a polarizer film, an optical film, and a liquid adhesive layer provided between the polarizer film and the optical film, A suction nozzle for sucking up excess liquid adhesive between the polarizer film and the optical film, A dilution liquid supply nozzle that supplies a dilution liquid to the inside of the suction nozzle and / or to the tip of the suction nozzle, The system includes a sensor that monitors the internal pressure of the dilution liquid supply nozzle and / or the flow rate of the liquid flowing through the dilution liquid supply nozzle, For each suction nozzle, a dilution liquid is supplied to the tip of the suction nozzle from both an upstream liquid supply nozzle located on the upstream side in the transport direction of the film laminate, and a downstream liquid supply nozzle located on the downstream side in the transport direction of the film laminate. A polarizing plate manufacturing apparatus that monitors the internal pressure and / or flow rate for both the upstream liquid supply nozzle and the downstream liquid supply nozzle.

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