JP5766909B2 - Optical film bonding method - Google Patents

Description

  The present invention relates to a method for bonding an optical film to a substrate.

  In recent years, liquid crystal display devices are used in various devices. In general, the production of such a liquid crystal display device includes a step of bonding various optical films on a liquid crystal display substrate.

  As a method for laminating such an optical film, as shown in FIG. 6, a strip-shaped film 100 in which a release film 102 is stuck to an optical film 101 via an adhesive layer (not shown) is used. Leave at least the optical film 101 and the pressure-sensitive adhesive layer in a direction perpendicular to the longitudinal direction, separate the release film 102 from the film piece cut out by the cutting, and attach the adhesive surface on the optical film 101 to the substrate 105. A method of attaching a pair of rollers 104 to corresponding positions is known (for example, see Patent Document 1).

  In the above method, as shown in FIG. 7, the optical film 101 can be continuously bonded to the substrate 105 by repeating the above-described operation.

  Further, in the cited document 2, the front end of the optical film is used to prevent deformation of the pressure-sensitive adhesive layer of the optical film (protrusion in a mountain shape: defective streaks) that accompanies the suspension of the laminating operation with the separated film peeled off. The technique which peels a separator film over a certain range beforehand from the part to the advancing direction is disclosed.

  Furthermore, in the cited document 3, a release film having a pressure-sensitive adhesive layer formed on the surface of a strip-shaped optical film having at least one surface made of a non-adhesive surface is optically inserted through the pressure-sensitive adhesive layer. A technique is disclosed in which a release film bonded to an optical film is bonded to a non-adhesive surface of the film, and then the release film is peeled off from the pressure-sensitive adhesive layer, and the optical film is bonded to a display substrate via the pressure-sensitive adhesive layer. Yes. And it is disclosed by the said technique that a defect inspection can be favorably performed with respect to the optical film before a release film is bonded together, and as a result, manufacturing cost can be reduced.

Japanese Patent Laying-Open No. 2004-361741 (released on December 24, 2004) JP 2004-338408 A (released on December 2, 2004) JP 2009-205138 A (published on September 10, 2009)

  However, in the configurations of Patent Documents 1 and 3, bubbles (referred to as “bonded bubbles”) as shown in FIG. 8 are mixed between the optical film 101 and the substrate 105, or streak-like defects are generated. This causes a problem.

  Moreover, in the structure of patent document 2, since it is necessary to use the optical film of a magnitude | size larger than the predetermined area | region in a to-be-adhered thing, production efficiency is bad.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to bond an optical film capable of suppressing air bubbles and streak defects between the optical film and the substrate with high production efficiency. To realize the method.

  In order to solve the above-mentioned problems, the present inventor has intensively studied the cause of air bubbles mixed between the optical film and the substrate. As a result, it was considered that the exposure of the pressure-sensitive adhesive layer to the outside air for a relatively long time was one of the causes of air bubbles mixing between the optical film and the substrate.

  Specifically, in the conventional optical film laminating method, as shown in FIG. 7, while laminating the previous optical film 101, the release film 102 in the belt-like film 100 used for the next laminating. Is peeled off (for example, see FIG. 11 and paragraph [0094] of Patent Document 1 and FIGS. 1 and 4 of Patent Document 2).

  In addition, in patent document 3, while performing pasting of the previous optical film 101, although the one part state of the peeling film 102 in the strip | belt-shaped film 100 used for the next bonding is not specifically disclosed. If it is those skilled in the art, like patent documents 1 and 2, it is clear that a part of exfoliation film 102 in beltlike film 100 used for the next pasting has exfoliated.

  For this reason, a part of adhesive layer in the strip | belt-shaped film 100 peels until the past board | substrate 105 is conveyed after the pasting of the previous optical film 101 is completed, and the next pasting is performed. You will be exposed to the open air. The adhesive layer in the strip-like film 100 from which the release film 102 has been peeled is exposed to the outside air until the past optical film 101 is bonded and the next substrate 105 is transported. It was considered that the pressure-sensitive adhesive was deformed and bubbles were mixed in the pressure-sensitive adhesive layer, and as a result, bubbles were mixed between the optical film and the substrate.

  Then, this inventor suppresses mixing of the bubble between an optical film and a board | substrate by performing peeling of the peeling film in the strip | belt-shaped film used for a bonding process only after the previous bonding process is completed. As a result, the present inventors have newly found that it is possible to suppress the streak-like defects and have completed the present invention. On the other hand, since the tact calculation at the time of conveyance was made on the basis of conveyance of a panel (those with an optical film bonded to a substrate), the timing at which the peeling film is peeled off from the polarizing plate is the previous bonding. It was before the process was completed. Therefore, the release film is kept waiting in a state where the release film is partially peeled off.

  That is, the optical film laminating method according to the present invention is a belt-shaped film for conveying in the longitudinal direction a belt-like film having a release film stuck on the optical film via an adhesive layer in order to solve the above-mentioned problems. After the film transporting step, the substrate transporting step for transporting the substrate, and the strip-shaped film transporting step, the optical film and the adhesive layer in the strip-shaped film, the length corresponding to the bonding region in the substrate, leaving the release film. A cutting step for cutting the film, a peeling film separating step for separating the release film from the belt-like film, and a pressure-sensitive adhesive layer in the belt-like film from which the release film has been peeled, The optical film is continuously bonded to the substrate by repeating a series of processes including a combination process, and in the next series of processes. That the release film separation process is characterized by performing only after bonding step in the previous series of steps is completed.

  According to the said method, in order to perform a peeling film separation process only after the previous bonding process is completed, the adhesive layer in a strip | belt-shaped film is exposed to external air until the previous bonding process is completed. Can be prevented. For this reason, it can suppress that the adhesive in an adhesive layer deform | transforms and a bubble mixes in an adhesive layer. As a result, it is possible to suppress mixing of bubbles and generation of streak defects between the optical film and the substrate.

  Moreover, in the said method, an optical film can be used efficiently and optical film bonding can be performed with high production efficiency.

  In addition, in paragraphs [0024] to [0025] of Patent Document 3, the “manufacturing method of the optical display unit according to the third aspect of the present invention does not cut the release film bonded to the optical film. The method further includes a cutting step of cutting the optical film and the pressure-sensitive adhesive layer, and the optical film and the pressure-sensitive adhesive layer after being cut are conveyed through the release film. According to the present invention, the adhesive layer that is the bonding surface of the optical film can be configured not to be exposed until just before the bonding, so that foreign matters can be prevented from being mixed into the bonding surface of the optical film. Has been. This simply describes the effect on the “method of cutting the release film bonded to the optical film”, and Patent Document 3 states that “peeling of the release film in the band-shaped film used in the bonding step is performed. Since nothing is specifically disclosed about “to be performed only after the pasting step is completed”, it is difficult for those skilled in the art to arrive at the present invention from Patent Document 3 and the like.

  In the optical film bonding method according to the present invention, the release film separation step is performed only after the substrate used for bonding with the strip-shaped film after the release film separation step is conveyed to the start position of the bonding step. Is preferred.

  According to the said method, since it can prevent that an adhesive layer is exposed to external air until it conveys the board | substrate used for bonding to the starting position of the said bonding process, the adhesive in an adhesive layer is It can deform | transform and can suppress more that a bubble mixes in an adhesive layer. As a result, it is possible to further suppress the mixing of bubbles and the generation of streak defects between the optical film and the substrate.

  In the bonding method of the optical film which concerns on this invention, it is preferable to perform the said peeling film separation process in a series of processes only after the said cutting process in the same process.

  According to the said method, since the said peeling film isolation | separation process is performed only after the said cutting process, the time when an adhesive layer touches external air can further be shortened.

  In the bonding method of the optical film which concerns on this invention, it is preferable to perform the said peeling film isolation | separation process simultaneously with the said bonding process.

  According to the above method, the time during which the pressure-sensitive adhesive layer is exposed to the outside air can be further shortened.

  As described above, the optical film laminating method according to the present invention is characterized in that the peeling film separating step in the next series of steps is performed only after the pasting step in the previous series of steps is completed. .

  For this reason, there exists an effect that generation | occurrence | production of the bubble mixing between the optical film and a board | substrate and generation | occurrence | production of a stripe defect can be suppressed with high production efficiency.

It is the front view which showed typically the strip | belt-shaped film conveyance process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate. It is the front view which showed typically the board | substrate conveyance process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate. It is the front view which showed typically the cutting process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate. It is the front view which showed typically the peeling film separation process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate. It is the front view which showed typically the bonding process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate. It is the front view which showed typically one process in the pasting method of the conventional optical film. It is the front view which showed typically another 1 process in the pasting method of the conventional optical film. It is a figure which shows typically the bonding bubble which generate | occur | produces in the bonding method of the conventional optical film.

  An embodiment of the present invention will be described as follows.

  The optical film laminating method according to the present embodiment is optical by repeating a series of steps including a strip-shaped film conveying step, a substrate conveying step, a cutting step, a peeling film separating step, and a laminating step. This is a method of continuously bonding a film to a substrate. Hereinafter, each process is demonstrated based on FIGS.

(1) Band-shaped film conveyance process FIG. 1: is the front view which showed typically the band-shaped film conveyance process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate.

  As shown in FIG. 1, in the belt-shaped film transporting step, the belt-shaped film 3 having the release film 2 attached on the optical film 1 via an adhesive layer (not shown) is transported in the longitudinal direction. is there.

  More specifically, in the band-shaped film conveyance process of the present embodiment, the band-shaped film 3 is cut in a length corresponding to the bonding region in the substrate 5 (see FIG. 2) in the subsequent cutting process. The belt-like film 3 is transported so that the length from the leading edge to the position where it is cut in the cutting step corresponds to the bonding area in the substrate 5 (see FIG. 2).

  In the present embodiment, the belt-like film 3 is unwound from the wound unwinding roll 4, and the unwound belt-like film 3 is wound from the side of the release film at the edge portion 6 having a sharp tip. The release film 2 is separated from 3, and the separated release film 2 is taken up by a take-up roll 9.

  The unwinding of the strip film 3 from the unwinding roll 4 can be performed, for example, by transporting the strip film 3 by a supply roller that sandwiches the strip film 3 from both sides.

  Here, the control of the position of the belt-like film 3 is performed by, for example, inputting a necessary length of the belt-like film 3 in advance into a computer or the like that controls the feeding roller and rotating the feeding roller based on the setting. be able to. Further, a sensor for detecting the position of the belt-like film 3 may be installed and controlled while monitoring the position of the belt-like film 3.

  In the method according to the present embodiment, the separation of the release film 2 in the strip film 3 used in the bonding process in the next series of steps is performed only after the bonding process in the previous series of steps is completed. For this reason, in this Embodiment, until the bonding process in the next series of steps is completed, the band-like film used for the next series of steps is only before the position P where the release film 2 is separated from the band-like film 3. 3 is not conveyed.

  The adhesive constituting the pressure-sensitive adhesive layer includes (meth) acrylate, oxetane, styrene butadiene rubber, butyl rubber, natural rubber, silicone rubber, polyisoprene, polybutene, polyvinyl ether, and acrylic resin. And polyester type.

  Examples of the substrate include a liquid crystal display substrate, a plasma display substrate, an organic EL substrate, a TFT substrate, a glass substrate used for a printed substrate, a synthetic resin substrate, and the like, and a substrate on which components such as cells and electrodes are formed in advance. May be used.

  As the release film, acrylic resin film, acetyl cellulose resin film including triacetyl cellulose film, polyester resin film, polyolefin resin film which is a polymer of chain or cyclic olefin, polycarbonate resin film, Examples thereof include films made of a thermoplastic resin such as a polyether ether ketone resin film, a polysulfone resin film, and an ethylene vinyl acetate copolymer film.

  Examples of the optical film include a polarizing film and a retardation film, and a composite film in which two or more of these are combined may be used.

(2) Board | substrate conveyance process FIG. 2: is the front view which showed typically the board | substrate conveyance process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate.

  As shown in FIG. 2, a board | substrate conveyance process is a process of conveying the board | substrate 5 to the predetermined | prescribed position for performing a bonding process. The substrate 5 can be transported by a conventionally known method such as a transport roller.

  The timing for carrying out the substrate transporting process is not particularly limited, but it is completed by the time the peeled film separating process for transporting the substrate 5 is started from the viewpoint of suppressing air bubbles from being mixed into the adhesive layer. It is preferable.

(3) Cutting Process FIG. 3 is a front view schematically showing a cutting process when the optical film according to the present embodiment is bonded to a substrate.

  As shown in FIG. 3, the cutting step is a length corresponding to the bonding region in the substrate 5 except for the optical film 1 and the pressure-sensitive adhesive layer in the belt-like film 3 and the release film 2 after the belt-like film conveying step. It is the process of cutting into.

  The cutting can be performed by the cutting means 8, for example. Examples of the cutting means 8 include a hydraulic cutter using a Thomson blade or a guillotine cutter using a motor crank, a laser cutter, a round blade rolling cutter, a round blade knife blade pulling cutter, and the like.

  In the present embodiment, the band-shaped film 3 is cut in a direction substantially perpendicular to the longitudinal direction, but the cutting direction can be appropriately changed according to the shape of the required optical film.

(4) Peeling film separation process FIG. 4: is the front view which showed typically the peeling film separation process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate.

  In this embodiment, the release film separation step is performed almost simultaneously with the bonding step.

  As shown in FIG. 4, the release film separation step is a step of separating the release film 2 from the strip-like film 3 cut out by the cutting.

  In the release film separation step in the present embodiment, the cut strip film 3 is wound around the edge portion 6 having a sharp tip from the release film 2 side, and the release film 2 is peeled off from the strip film 3. .

  Moreover, in this Embodiment, if the said peeling film isolation | separation process is performed only after the bonding process in a previous series of processes is completed, a peeling film separation process will be bonded with the strip | belt-shaped film after the said peeling film separation process. The substrate 5 used for the bonding may be performed before being conveyed to the start position of the bonding step, may be performed simultaneously with the conveyance, or may be performed after the conveyance, but the substrate 5 is started of the bonding step. It is preferable to carry out only after transporting to the position.

  By carrying out the release film separation step only after transporting the substrate 5 used for pasting with the strip-like film 3 after the release film separation step to the start position of the pasting step, adhesion is performed during the transportation of the substrate 5. The agent layer can be prevented from being exposed to the outside air, and as a result, the adhesive component in the pressure-sensitive adhesive layer expands, and bubbles can be mixed and the occurrence of streak-like defects can be further suppressed.

  In the present embodiment, the case where the strip film 3 is separated from the strip film 3 by winding the strip film 3 from the release film 2 side at the edge portion 6 having a sharp tip has been described. This is not a limitation. For example, the release film 2 may be separated from the belt-like film 3 by using a roll instead of the edge portion 6 and winding the belt-like film 3 from the release film 2 side in the roll.

  Moreover, although this Embodiment demonstrated the case where the said peeling film isolation | separation process was performed only after the said cutting process in the process, it does not restrict to this. For example, the cutting step may be performed during the release film separation step. More specifically, a cutting step may be performed when the strip-shaped film 3 comes to a predetermined position during the release film separation step.

(5) Bonding process FIG. 5: is the front view which showed typically the bonding process at the time of bonding the optical film which concerns on this Embodiment to a board | substrate.

  As shown in FIG. 5, the bonding step is a step of bonding the pressure-sensitive adhesive layer in the strip film 3 from which the release film 2 has been separated to the bonding region in the substrate 5.

  In the bonding step of the present embodiment, bonding is performed while feeding the band-shaped film 3 and the substrate 5 from which the release film 2 has been separated to the pair of bonding rollers 10.

  Here, the cut-out strip film 3 and the strip-like film 3 (uncut strip-like film) used for pasting the next substrate are all peeled off from the cut-out strip film 3. Are connected to each other through the release film 2. For this reason, until all the peeling films 2 are peeled from the cut-out strip film 3, the uncut belt-like film 3 is also fed out together with the cut-out strip film 3.

  Here, in the conventional method, before the pasting step of the previous substrate is completed, the end of the strip-shaped film 3 passes through the position where the release film of the strip-shaped film is separated. A peeling film will be isolate | separated in a part of 3, and a peeling film separation process will be performed before the previous bonding process is completed (refer FIG. 7).

  On the other hand, in this Embodiment, as shown in FIG. 5, until the said bonding process of the board | substrate 5 is completed, the peeling film separation process of the strip | belt-shaped film 3 used for the bonding with respect to the following board | substrate is performed. Instead, the leading end of the strip-shaped film 3 is sent out only to a position before the position P where the release film 2 is separated from the strip-shaped film 3.

  For this reason, according to the method which concerns on this Embodiment, compared with the conventional method, it prevents that the adhesive layer in the strip | belt-shaped film 3 is exposed to external air until the previous bonding process is completed. be able to. Therefore, the adhesive component in the pressure-sensitive adhesive layer expands, and bubbles can be mixed in and the occurrence of streak defects can be suppressed. As a result, bubbles are mixed or streaked between the optical film 1 and the substrate 5. The occurrence of defects can be suppressed.

  As described above, in the method according to the present embodiment, the strip-shaped film 3 and the substrate 5 that have been cut out are fed to the bonding roller 10 side, whereby the strip-shaped film 2 is separated and the strip-shaped film 2 is separated. The pressure-sensitive adhesive layer in the film 3 is bonded to the corresponding position on the substrate 5. And after the said bonding process is completed, with respect to the next board | substrate, it is optical by performing the strip | belt-shaped film conveyance process mentioned above, a board | substrate conveyance process, a cutting process, a peeling film separation process, and a bonding process similarly. The film can be continuously bonded to the substrate.

  In the method according to the present embodiment, the peeling film separation step for the next substrate is performed only after the bonding step is completed, but the other steps are performed before the bonding step is completed. May be.

  In the above description, the case where the release film separation step is performed almost simultaneously with the bonding step is described, but the present invention is not limited to this. After performing a peeling film separation process, you may perform a bonding process. If the separation of the release film in the band-shaped film used in the bonding step is performed only after the previous bonding step is completed, the same effects as those of the present embodiment can be obtained.

  However, when performing the said peeling film isolation | separation process simultaneously with the said bonding process like this embodiment, since the time when an adhesive layer touches external air can be shortened, an effect is especially large.

  Moreover, in this Embodiment, you may perform the position preparation process which adjusts the position of the board | substrate 5 and the strip | belt-shaped film 3 cut out before the bonding process, and in that case, the said position preparation process is performed. After that, it is preferable to perform a release film separation step.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The bonding method of the optical film of this invention can suppress mixing of the bubble between an optical film and a board | substrate. For this reason, it can use suitably for various substrates, such as a liquid crystal display substrate, which needs to bond an optical film.

DESCRIPTION OF SYMBOLS 1 Optical film 2 Peeling film 3 Strip | belt-shaped film 4 Unwinding roll 6 Edge part 8 Cutting means 9 Winding roll 10 Bonding roller 100 Band-shaped film 101 Optical film 102 Peeling film 104 Roller 105 Board | substrate

Claims (3)

A belt-shaped film transporting step for transporting a belt-shaped film having a release film attached to the optical film via an adhesive layer in the longitudinal direction;
A substrate transfer process for transferring the substrate;
After the belt-shaped film transporting step, the optical film and the pressure-sensitive adhesive layer in the belt-shaped film are cut to a length corresponding to the bonding region in the substrate, leaving the release film, and
A release film separating step for separating the release film from the strip film,
A bonding step of bonding the pressure-sensitive adhesive layer in the strip-shaped film from which the release film has been peeled, to the bonding region in the substrate;
Is a method of continuously bonding an optical film to a substrate by repeating a series of steps including:
The release film separation step is performed only after the substrate used for bonding with the strip film after the release film separation step is conveyed to the start position of the bonding step,
An optical film laminating method, wherein the peeling film separating step in the next series of steps is performed only after the pasting step in the previous series of steps is completed. The release film separation step in a series of steps, bonding method of the optical film according to claim 1, characterized in that only after the cutting step. The method for laminating an optical film according to claim 1 or 2, wherein the peeling film separating step is performed simultaneously with the laminating step.

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