CN111432979A - Method for cutting laminated film and method for manufacturing same - Google Patents

Abstract

The present invention provides a method for cutting a laminated Film (FX) in which a plurality of resin layers (S3, S5, S4) having different materials are laminated is cut along a cutting line (C). The plurality of resin layers (S3, S5, S4) are cut by scanning the cutting line (C) of the laminated Film (FX) with a plurality of laser beams (L1, L2) having different wavelengths.concretely, among the plurality of resin layers (S3, S5, S4), the resin layers (S4, S5) showing a photodecomposition reaction due to absorption of a 1 st laser beam (L1) are cut with a 1 st laser beam (L1), and among the plurality of resin layers (S3, S5, S4), the resin layer (S3) showing a photodecomposition reaction due to absorption of a 2 nd laser beam (L2) is cut with a 2 nd laser beam (L2).

Description

Method for cutting laminated film and method for manufacturing same

Technical Field

The present invention relates to a method for cutting a laminated film in which a plurality of resin layers having different materials are laminated, and a method for manufacturing the same.

The present application claims priority based on japanese patent application No. 2017-235351, applied on 12/7/2017, and japanese patent application No. 2018-208864, applied on 11/6/2018, the contents of which are incorporated herein by reference.

Background

For example, optical films such as a polarizing plate and a retardation film (retardation plate) are attached to optical display panels such as a liquid crystal panel and an organic E L panel, and in general, these optical films are made by winding a long film from a roll of a material and cutting (dicing) the wound film into a width and a length corresponding to the optical display panel.

In the cutting process of an optical film, a cutter has been used. However, when the cutting process is performed by a cutter, foreign matter such as film dust is likely to be generated during the cutting process. When the optical film having such foreign matter adhered thereto is stuck to an optical display panel, display defects and the like may occur in the optical display panel.

Therefore, in recent years, an optical film is cut (cut) using a laser (see, for example, patent documents 1 to 3). Specifically, patent document 1 discloses a method for producing a resin film medium, which includes a 1 st dicing step of dicing a part of a functional layer and a resin film by a laser and a 2 nd dicing step of dicing the remaining resin film by a dicing blade, in dicing a laminate including the resin film and one or more functional layers.

On the other hand, patent document 2 discloses a method for manufacturing a polarizing plate in which other layers constituting the polarizing plate are cut with only a release film of the polarizing plate left, the layer immediately before the layer formed of the laser low absorption film is cut with a laser from the surface protective film layer, and then the layer formed of the laser low absorption film is cut with a cutter.

On the other hand, patent document 3 discloses a method for cutting a polarizing plate, including a groove forming step of cutting a high absorptance film by irradiation of laser light and forming a groove in a low absorptance film; and a tearing process of tearing the low absorption film along the groove.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5359356

Patent document 2: japanese patent No. 4743339

Patent document 3: japanese patent No. 5481300

Disclosure of Invention

Problems to be solved by the invention

A typical polarizing plate is configured as a laminated film in which a polyvinyl alcohol (PVA) layer serving as a polarizer is sandwiched between a triacetyl cellulose (TAC) layer serving as an upper protective layer and a cycloolefin polymer (COP) layer serving as a lower protective layer, for example.

When such a laminated film is cut with a laser beam (for example, a carbon dioxide laser, a wavelength of 9.4 μm), a layer which is easy to cut (a layer having a high laser light absorption rate) is formed other than the COP layer, and therefore, the laminated film is cut by photodecomposition processing with less heat generation, and the cross-sectional quality is favorably maintained. On the other hand, since the COP layer is a layer that is difficult to cut (a layer having a low laser light absorption rate), the COP layer is cut by thermal processing using molecular vibration, and there is a problem that the cross-sectional quality is deteriorated.

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide a method for cutting a laminated film, such as a polarizing plate, in which a plurality of resin layers having different materials are laminated, can be cut with high accuracy, and the cross-sectional quality of the cut laminated film can be maintained satisfactorily, and a method for producing a laminated film using the method for cutting a laminated film.

Means for solving the problems

As a method for solving the above-described problems, according to an aspect of the present invention, there is provided a method for cutting a laminated film in which a plurality of resin layers different in material are laminated is cut along a cutting line, wherein the plurality of resin layers are cut by scanning the cutting line of the laminated film with a plurality of laser beams different in wavelength.

In the method of cutting the laminated film, a resin layer showing a photodecomposition reaction due to absorption of the 1 st laser light among the plurality of resin layers may be cut by the 1 st laser light, and a resin layer showing a photodecomposition reaction due to absorption of the 2 nd laser light among the plurality of resin layers may be cut by the 2 nd laser light, by scanning a cutting line of the laminated film with a 1 st laser light and a 2 nd laser light having a different wavelength from the 1 st laser light.

In the method of cutting the laminated film, the 1 st laser may be a laser beam excited by a carbon dioxide laser, and the 2 nd laser may be a laser beam excited by a YAG laser, an excimer laser, or a semiconductor laser.

According to another aspect of the present invention, there is provided a method for manufacturing a laminated film in which a plurality of resin layers having different materials are laminated, the method including a dicing step of dicing the plurality of resin layers along dicing lines, wherein the dicing step uses any of the above-described dicing methods.

In the method for manufacturing the laminated film, the laminated film is a polarizing plate in which at least a cycloolefin polymer (COP) layer and a polyvinyl alcohol (PVA) layer are laminated, the PVA layer may be cut by the 1 st laser, and the COP layer may be cut by the 2 nd laser.

In the method of manufacturing the laminated film, the laminated film may further include a triacetyl cellulose (TAC) layer, the laminated film may be a polarizing plate in which the COP layer, the PVA layer, and the TAC layer are sequentially laminated, the TAC layer and the PVA layer may be cut by the 1 st laser, and the COP layer may be cut by the 2 nd laser.

In the method of manufacturing the laminated film, the 2 nd laser light may be laser light excited by a YAG laser, an excimer laser, or a semiconductor laser.

In the method for manufacturing a laminated film, the laminated film may be a laminated film for an image display device including at least 2 or more of flexibility selected from a circular polarizing plate, a window film, and a touch sensor.

Effects of the invention

As described above, according to the aspect of the present invention, the laminated film in which the plurality of resin layers having different materials are laminated is cut by photolysis processing with little heat generation using laser beams having different wavelengths, whereby the plurality of resin layers constituting the laminated film can be cut with high accuracy, and the cross-sectional quality of the cut laminated film can be maintained favorably.

Drawings

Fig. 1 is a cross-sectional view showing a stacked structure of polarizing plates.

Fig. 2 is a perspective view showing an example of the laser processing apparatus.

Fig. 3 is a perspective view showing a specific configuration of the laser irradiation device.

Fig. 4 is a cross-sectional view for explaining a cutting process of a polarizing plate.

FIG. 5 is a graph showing the transmittance of COP, PVA, TAC and PET for light having a wavelength of 2.0 to 14.0 μm.

FIG. 6 is a graph showing the transmittance of COP for light having a wavelength of 200 to 500 μm.

Fig. 7 is a perspective view showing another example of the laser processing apparatus.

Fig. 8 is a cross-sectional view showing a laminated structure of polarizing plates to which surface protective films are attached.

Fig. 9 is a cross-sectional view for explaining a cutting process of the polarizing plate shown in fig. 8.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the drawings used in the following description, for the sake of easy understanding of the features, the portions to be the features are shown in an enlarged scale in some cases, and the dimensional ratios of the respective components are not necessarily the same as the actual ones. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not necessarily limited to these examples, and may be appropriately modified and implemented within a range not changing the gist thereof.

(method of cutting laminated film)

The method for cutting a laminated film to which a plurality of resin layers having different materials are laminated is characterized in that, when the laminated film is cut along a cutting line, the plurality of resin layers are cut by scanning the cutting line of the laminated film with a plurality of laser beams having different wavelengths.

In this embodiment, as a specific example of a cutting method to which the laminated film of the present invention is applied, for example, a case of cutting a polarizing plate (laminated film) FX shown in fig. 1 is exemplified.

Polarizing plate FX as shown in fig. 1, the uppermost layer of polarizing plate FX is protected by surface protective film S2. The surface protective film S2 is formed into a sheet of a predetermined size together with the polarizing plate FX by a cutting process, and is attached to a liquid crystal panel, and then peeled and removed from the polarizing plate FX.

As such a surface protective film S2, a polyethylene terephthalate (PET) film can be used.

The polarizing plate FX has a laminated structure in which a polarizer layer S5 (resin layer) is sandwiched between a pair of protective layers S3 and S4 (resin layers). Specifically, the polarizing plate FX of the present embodiment is a laminated film in which a cycloolefin polymer (COP) layer as a protective layer S3 on the lower layer side, a polyvinyl alcohol (PVA) layer as a polarizer layer S5, and a triacetyl cellulose (TAC) layer as a protective layer S4 on the upper layer side are sequentially laminated.

The laminated structure of the polarizing plate FX shown in fig. 1 is merely an example, and is not necessarily limited to such a laminated structure, and a material, a thickness, and the like used for each resin layer (film) may be appropriately changed as a laminated film in which a plurality of resin layers (films) having different materials are laminated.

(Flexible image display device)

The method for producing a laminated film to which the present invention is applied can be suitably used for producing a laminated film suitable for a flexible image display device (flexible laminated film for an image display device).

The flexible image display device includes a flexible laminate film for an image display device and an organic E L display panel, and is configured to be freely bendable while disposing a flexible laminate for an image display device on the visible side of the organic E L display panel.

The flexible laminate for an image display device may be a laminate containing at least 2 or more selected from a window film (hereinafter, may be abbreviated as "window"), a circularly polarizing plate, and a touch sensor. The window, the circularly polarizing plate, and the touch sensor are all members having flexibility (flexibility).

The order of stacking the window, the circularly polarizing plate, and the touch sensor is arbitrary, but a configuration in which the window, the circularly polarizing plate, and the touch sensor are stacked in this order from the visible side, or a configuration in which the window, the touch sensor, and the circularly polarizing plate are stacked in this order from the visible side is preferable. If the circularly polarizing plate is present on the visible side of the touch sensor, the pattern of the touch sensor is not easily recognized, and the visibility of the display image is improved, which is preferable.

The window, the circularly polarizing plate, and the touch sensor may be laminated by bonding using an adhesive, or the like. In addition, a light-shielding pattern may be formed on at least one surface of any of the window, the circularly polarizing plate, and the touch sensor.

(Window)

The window is disposed on the visible side of the flexible image display device, and serves as a protective layer for protecting other components from external impact or environmental changes such as temperature and humidity.

Conventionally, glass has been used as such a protective layer, but the window of a flexible image display device is formed of a transparent substrate having flexibility as described above, rather than a rigid and hard material like glass. The transparent substrate may comprise a hard coat layer on at least one side.

(transparent substrate)

The transparency of the transparent substrate used for a window is preferably 70% or more, more preferably 80% or more, in visible light transmittance. The transparent substrate is not particularly limited as long as it is a polymer film having transparency, and any material may be used.

Specifically, polyolefins such as polyethylene, polypropylene, polymethylpentene, and cycloolefin derivatives having a unit containing a norbornene or cycloolefin monomer; (modified) celluloses such as diacetyl cellulose, triacetyl cellulose, and propionyl cellulose; acrylic acids such as methyl methacrylate (co) polymers; polystyrenes such as styrene (co) polymers; acrylonitrile/butadiene/styrene copolymers; acrylonitrile/styrene copolymers; ethylene-vinyl acetate copolymers; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyarylate; polyamides such as nylon; polyimides such as polyimides, polyamide imides and polyether imides; polysulfones such as polyether sulfones and polysulfones; polyvinyl alcohols; polyvinyl acetals; polyurethanes; and films of polymers such as epoxy resins. Further, an unstretched film or a uniaxially or biaxially stretched film comprising these polymers may be used.

These polymers may be used alone or in combination of 2 or more. Among them, a polyamide film, a polyamideimide film, a polyimide film, a polyester film, an olefin film, an acrylic film, and a cellulose film, which are excellent in transparency and heat resistance, are preferably used.

It is preferable to disperse inorganic particles such as silica, organic fine particles, rubber particles, and the like in the transparent base material. The transparent substrate may contain compounding agents such as colorants such as pigments and dyes, fluorescent brighteners, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, and solvents. The thickness of the transparent substrate is preferably 5 to 200 μm, and more preferably 20 to 100 μm.

(hard coating)

In order to prevent scratches on the surface of the transparent substrate (to improve scratch resistance), a hard coat layer may be provided on at least one side of the window. The thickness of the hard coat layer is not particularly limited, and may be, for example, 2 to 100 μm. If the thickness of the hard coat layer is less than 2 μm, it is difficult to ensure sufficient scratch resistance. On the other hand, if the thickness of the hard coat layer is more than 100 μm, flexibility may be reduced, and curling due to curing shrinkage may be caused.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material which forms a crosslinked structure by irradiation with an active energy ray or thermal energy, and among them, a material which forms a crosslinked structure by irradiation with an active energy ray, that is, a material which is cured by an active energy ray is preferable.

The hard coat composition contains at least 1 polymer of a radical polymerizable compound and a cation polymerizable compound. The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group may be any functional group that can cause a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specific examples thereof include a vinyl group and a (meth) acryloyl group. When the radical polymerizable compound has 2 or more radical polymerizable groups, the radical polymerizable groups may be the same or different.

The number of radical polymerizable groups contained in 1 molecule of the radical polymerizable compound is preferably 2 or more in order to increase the hardness of the hard coat layer. The radical polymerizable compound is preferably a compound having a (meth) acryloyl group in view of high reactivity, and preferably a compound called a multifunctional acrylate monomer having 2 to 6 (meth) acryloyl groups in 1 molecule, an oligomer called an epoxy (meth) acrylate, a urethane (meth) acrylate, or a polyester (meth) acrylate having several (meth) acryloyl groups in a molecule and having a molecular weight of several hundreds to several thousands is used. Preferably, the ink composition contains 1 or more selected from epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate.

The cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetane group, or a vinyl ether group. The number of the cationically polymerizable groups contained in 1 molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the scratch resistance of the hard coat layer.

The cationically polymerizable compound is preferably a compound having at least 1 cyclic ether group of an epoxy group and an oxetanyl group as a cationically polymerizable group. A cyclic ether group is preferable because the shrinkage accompanying the polymerization reaction is small. Further, compounds having an epoxy group among cyclic ether groups are readily available from the market in various structures, and do not adversely affect the scratch resistance and durability of the resulting hard coating layer.

In addition, when the hard coat composition contains a radical polymerizable compound and a cation polymerizable compound, there is an advantage that the compatibility with the radical polymerizable compound can be easily controlled. The oxetanyl group among the cyclic ether groups has the effect of easily increasing the polymerization degree as compared with an epoxy group, being low in toxicity, accelerating the rate of formation of a network of the obtained cationic polymerizable compound in the obtained hard coat layer, and preventing an unreacted monomer from remaining in the film even in a region where the hard coat layer is mixed with the radical polymerizable compound. In addition, there are advantages in that a separate network is formed.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ethers of alicyclic polyhydric alcohols; alicyclic epoxy resins obtained by epoxidizing compounds containing a cyclohexene ring or a cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide or a peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl (meth) acrylate; bisphenols such as bisphenol a, bisphenol F and hydrogenated bisphenol a, or alkylene oxide adducts thereof; glycidyl ethers and novolac epoxy resins produced by the reaction of a derivative such as a caprolactone adduct with epichlorohydrin; glycidyl ether type epoxy resins derived from bisphenols, and the like.

The hard coating composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and the like. From among these, the polymerizable compound can be appropriately selected and used according to the kind of the polymerizable compound used. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating, and generate radicals or cations to advance radical polymerization and cationic polymerization.

The radical polymerization initiator may be any one that can release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

The active energy ray radical polymerization initiator includes a Type1 radical polymerization initiator which generates radicals by decomposition of molecules and a Type2 radical polymerization initiator which coexists with a tertiary amine and generates radicals by a hydrogen abstraction reaction, and they may be used alone or in combination.

The cationic polymerization initiator may be any initiator that can release a substance that initiates cationic polymerization by at least one of irradiation with active energy rays and heating. As the cationic polymerization initiator, for example, aromatic iodonium salts, aromatic sulfonium salts, cyclopentadienyl iron (II) complexes, and the like can be used. They can initiate cationic polymerization by some kind of irradiation with active energy rays or heating, or can initiate cationic polymerization by any kind of irradiation with active energy rays or heating, depending on the difference in structure.

The polymerization initiator may be contained in an amount of 0.1 to 10 wt% based on 100 wt% of the entire hard coat composition. When the content of the polymerization initiator is less than 0.1% by weight, it is difficult to sufficiently advance the curing, and it is difficult to achieve the mechanical properties and adhesion of the finally obtained coating film.

On the other hand, when the content of the polymerization initiator is more than 10% by weight, poor adhesion, a crack phenomenon, and a curl phenomenon due to curing shrinkage may occur.

The hard coating composition may further comprise one or more selected from solvents and additives. The solvent may be any solvent capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and any solvent conventionally known as a solvent for a hard coat composition in the art may be used without limitation. Examples of the additive include inorganic particles, a leveling agent, a stabilizer, a surfactant, an antistatic agent, a lubricant, and an antifouling agent.

[ circularly polarizing plate ]

For example, by converting external light incident to the display device into right-circularly polarized light, which is reflected by the organic E L panel and becomes left-circularly polarized light, the left-circularly polarized light can be blocked by the circular polarizing plate, and as a result, the influence of reflected light is suppressed, and only the light-emitting component of the organic E L is transmitted, whereby an image can be easily observed, and therefore, the circular polarizing plate is used.

In order to realize the function as circularly polarized light, it is necessary to laminate and combine a linearly polarizing plate and a λ/4 phase difference plate, and the angle between the absorption axis of the linearly polarizing plate and the slow axis of the λ/4 phase difference plate is theoretically 45 °, but in practice, it is only necessary to set the angle to 45 ° ± 10 °.

The linearly polarizing plate and the λ/4 phase difference plate do not necessarily need to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis may be satisfied in the above range. It is preferred to achieve fully circularly polarized light at all wavelengths. However, this is not necessarily required in practice, and therefore the circularly polarizing plate used in the flexible image display device may include an elliptically polarizing plate. Further, the visibility in a state where the polarized sunglasses are worn may be improved by laminating a λ/4 phase difference film on the visible side of the linear polarizing plate and setting the emitted light to circularly polarized light.

The linear polarizing plate is a functional layer having a function of passing light vibrating in the transmission axis direction and blocking polarized light of vibration components perpendicular thereto. The linearly polarizing plate may be configured to include a linearly polarizing plate alone or a linearly polarizing plate and a protective film attached to at least one surface of the linearly polarizing plate. The thickness of the linear polarizer may be 200 μm or less, and is preferably 0.5 to 100 μm. If the thickness of the linear polarizer is greater than 200 μm, flexibility may be reduced.

The linear polarizer is a member that functions as a polarizer layer in a linear polarizing plate, and examples thereof include a film-type polarizer produced by dyeing and stretching a polyvinyl alcohol (PVA) -based film. Further, the polarizing performance is exhibited by adsorbing a dichroic dye such as iodine to the PVA film oriented by stretching, or by orienting the dichroic dye by stretching the PVA film in a state of being adsorbed to the molecules of the PVA film.

In addition to the above, the film-type polarizing plate may be produced by various steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying. The stretching step and the dyeing step may be performed using a PVA-based film alone, or may be performed in a state of being laminated with another film such as polyethylene terephthalate. The PVA film used is preferably 10 to 100 μm in thickness and 2 to 10 times in draw ratio.

Although the linear polarizing plate having a film-type polarizer as a linear polarizer and the circularly polarizing plate having the linear polarizing plate have been described above, it is preferable to use a thinner polarizer (film polarizer) by making the thickness of the circularly polarizing plate thinner in order to improve the flexibility of the circularly polarizing plate.

An example of such a thin-film polarizing plate is a liquid crystal coating type polarizing plate formed by coating a liquid crystal polarizing composition. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound.

The liquid crystalline compound is preferably one having a property of exhibiting a liquid crystal state, and particularly one having a high-order alignment state such as a smectic state, because it can exhibit high polarization performance. Further, it preferably has a polymerizable functional group.

The dichroic dye compound is a dye that exhibits dichroism by being aligned together with the liquid crystal compound, and may have liquid crystal properties or a polymerizable functional group. A certain compound contained in a typical liquid crystal polarizing composition has a polymerizable functional group.

The liquid crystal polarizing composition preferably contains an initiator and a solvent, and may further contain additives such as a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, and a silane coupling agent.

The liquid crystal polarizing layer may be manufactured by coating a liquid crystal polarizing composition on an alignment film and forming a liquid crystal polarizing layer. Such a liquid crystal polarizing layer has an advantage that the thickness can be reduced as compared with a film type polarizing plate. In this case, the thickness of the liquid crystal polarizing layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

For example, an alignment film can be produced on a substrate by applying an alignment film-forming composition to an appropriate substrate and imparting alignment properties to the substrate by rubbing, polarized light irradiation, or the like.

The alignment film-forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like in addition to the alignment agent.

Examples of the orientation agent include polyvinyl alcohols, polyacrylates, polyamide acids, and polyimides. In the case of the application of photo-alignment (irradiation with polarized light), it is preferable to use an alignment agent containing a cinnamate group. The weight average molecular weight of the polymer used as the orientation agent may be 10000 to 1000000. The thickness of the alignment film is preferably 5 to 10000nm, and particularly preferably 10 to 500nm, since the alignment regulating force is sufficiently exhibited.

The liquid crystal polarizing layer formed on the substrate having the alignment film may be peeled off from the substrate, or a 2 nd substrate may be bonded to a laminate in which the substrate, the alignment film, and the liquid crystal polarizing layer are laminated, and the liquid crystal polarizing layer may be transferred to the 2 nd substrate. When the liquid crystal polarizing layer is transferred to the 2 nd substrate, the 2 nd substrate can be made to function as a protective film, a retardation plate, or a transparent substrate for a window.

As the protective film, any transparent polymer film may be used, and materials and additives exemplified as transparent substrates may be used. Among them, cellulose-based films, olefin-based films, acrylic films, and polyester-based films are preferably used. Further, the protective film may be a coating type protective film obtained by applying and curing a cationic curing composition such as an epoxy resin or a radical curing composition such as an acrylate.

Further, a plasticizer, an ultraviolet absorber, an infrared absorber, a pigment, a colorant such as a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like may be contained as necessary. The thickness of the protective film may be 200 μm or less, and preferably 1 to 100 μm. If the thickness of the protective film is more than 200 μm, flexibility may be reduced. In addition, the protective film may also function as a window.

The λ/4 phase difference plate is a film that imparts a phase difference of λ/4 in a direction (in-plane direction of the film) orthogonal to the traveling direction of incident light. The λ/4 retardation plate can be, for example, a stretched retardation plate produced by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. Further, a phase difference adjusting agent, a plasticizer, an ultraviolet absorber, an infrared absorber, a pigment, a colorant such as a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like may be contained as necessary. The thickness of the stretched retardation film is preferably 200 μm or less, and more preferably 1 to 100 μm. If the thickness of the tension type retardation film is larger than 200 μm, flexibility may be reduced.

The λ/4 retardation plate may be a liquid crystal coating type retardation plate formed by coating a liquid crystal composition. The liquid crystal composition for forming a liquid crystal-coated retardation plate contains a liquid crystal compound having a property of exhibiting a liquid crystal state such as a nematic state, a cholesteric state, or a smectic state. Some of the liquid crystalline compounds contained in the liquid crystal composition have a polymerizable functional group.

In addition, the liquid crystal composition may include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coated retardation plate can be produced by coating a liquid crystal composition on an alignment film and curing the coating to form a liquid crystal retardation layer in the same manner as in the above-described operation for the liquid crystal polarizing layer.

The liquid crystal coating type retardation plate can be formed to be thinner than the stretching type retardation plate. Specifically, the thickness of the liquid crystal polarizing layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm. The liquid crystal-coated retardation plate may be peeled from the substrate and then transferred to be laminated, or the substrate may be laminated as it is. The substrate may also function as a protective film, a retardation plate, or a transparent substrate for a window.

In general, a retardation plate often exhibits a larger birefringence as the wavelength is shorter, and exhibits a smaller birefringence as the wavelength is longer. In this case, since a phase difference of λ/4 cannot be given in all visible light regions, it is often designed to reach λ/4 for around 560nm, which is high in visibility. The retardation plate preferably has an in-plane retardation of 100 to 180nm, more preferably 130 to 150 nm.

When a reverse dispersion λ/4 phase difference plate using a material having a wavelength dispersion characteristic of birefringence opposite to that of the conventional one is used for the circularly polarizing plate, visibility is improved, which is preferable. When such a material is used as the tension type phase difference plate, for example, a material described in japanese patent application laid-open No. 2007-232873 and the like can be used. In the case of a liquid crystal coated retardation plate, the materials described in jp 2010-30979 a can be used.

As another method, a technique is known in which a λ/4 phase difference plate and a λ/2 phase difference plate are combined to obtain a wide-band λ/4 phase difference plate (see, for example, japanese patent application laid-open No. 10-90521). The lambda/2 phase difference plate is manufactured by the same material and method as the lambda/4 phase difference plate. In this case, the combination of the stretching type retardation plate and the liquid crystal coating type retardation plate is arbitrary, but it is preferable to use the liquid crystal coating type retardation plate because the film thickness can be reduced.

In order to improve the visibility of the circularly polarizing plate in the oblique direction, a method of laminating a front C-plate is also known (see, for example, japanese patent application laid-open No. 2014-224837). The positive C plate may be a liquid crystal coated retardation plate or a stretched retardation plate. The phase difference in the thickness direction is preferably from-200 to-20 nm, more preferably from-140 to-40 nm.

(touch sensor)

The touch sensor is a typical member used as an input tool of a flexible image display device. As the touch sensor, for example, various types of touch sensors such as a resistive film type, a surface acoustic wave type, an infrared ray type, an electromagnetic induction type, and a capacitance type can be used, and among them, the capacitance type is preferably used.

The capacitive touch sensor can be divided into an active region and an inactive region located in an outer region of the active region. The active region is a region corresponding to a region (display portion) of the display panel on which a screen is displayed, and is a region in which a user's touch is sensed. On the other hand, the inactive area is an area corresponding to an area (non-display portion) where no screen is displayed in the image display device.

The touch sensor may include: the liquid crystal display device includes a substrate having a flexible characteristic, a sensing pattern formed on an active region of the substrate, and sensing lines formed on an inactive region of the substrate and connected to an external driving circuit via the sensing pattern and a pad portion.

As the substrate having a flexible property, the same material as the transparent substrate of the window can be used. The substrate of the touch sensor preferably has a toughness of 2000 MPa% or more in order to suppress cracking of the touch sensor. More preferably, the toughness is 2000MPa to 30000 MPa%. Here, "toughness" refers to a property obtained from a Stress (MPa) -strain (%) curve (Stress-strain curve) obtained by a tensile test of a polymer material. That is, a tensile test is performed to obtain a stress (MPa) -strain (%) curve from the time of applying a stress to the fracture point of the test polymer material, and the curve is defined by the area of the curve obtained.

The sensing pattern may include a 1 st pattern formed along a 1 st direction and a 2 nd pattern formed along a 2 nd direction. The 1 st pattern and the 2 nd pattern are arranged in different directions from each other. The 1 st pattern and the 2 nd pattern are formed on the same layer, and in order to sense a touched point, the patterns must be electrically connected. The 1 st pattern is a form in which the unit patterns are connected to each other via a joint. On the other hand, the 2 nd pattern is a structure in which the unit patterns are separated from each other in an island-like form. Thus, in order to electrically connect the 2 nd pattern, an additional bridge electrode is required.

The sensing pattern may use a known transparent electrode material. Examples thereof include Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), zinc oxide (ZnO), Indium Zinc Tin Oxide (IZTO), Cadmium Tin Oxide (CTO), PEDOT (poly (3, 4-ethylenedioxythiophene)), Carbon Nanotubes (CNT), graphene, and a metal wire, and 2 or more of them may be used alone or in combination. Among them, ITO is preferably used.

The metal used for the metal wire is not particularly limited, but examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium (japanese laid-open: テレニウム), chromium, and the like. These may be used alone or in combination of 2 or more.

The bridge electrode may be formed on an upper portion of the sensing pattern with an insulating layer interposed therebetween. The bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, and may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of 2 or more of these metals.

Since the 1 st pattern and the 2 nd pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the tab of the 1 st pattern and the bridge electrode. In addition, the layer covering the sensing pattern may be formed. In the latter case, the bridge electrode may be connected to the 2 nd pattern via a contact hole formed in the insulating layer.

As a method for appropriately compensating for a difference in transmittance between a pattern region where a pattern is formed and a non-pattern region where no pattern is formed, specifically, as a method for appropriately compensating for a difference in light transmittance induced by a difference in refractive index between these regions, the touch sensor may further include an optical adjustment layer between the substrate and the electrode.

The optical adjustment layer may contain an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by applying a photocurable composition containing a photocurable organic binder and a solvent onto a substrate. In addition, the photocurable composition may include inorganic particles. The inorganic particles are used to increase the refractive index of the optical adjustment layer.

As the photocurable organic binder included in the photocurable composition, for example, a copolymer of monomers such as an acrylate monomer, a styrene monomer, and a carboxylic acid monomer can be used. The photocurable organic binder may be, for example, a copolymer containing repeating units different from each other, such as repeating units containing an epoxy group, repeating units containing an acrylate, repeating units containing a carboxylic acid, and the like.

Examples of the inorganic particles contained in the photocurable composition include zirconium dioxide particles, titanium dioxide particles, and aluminum oxide particles. The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing assistant.

(adhesive layer)

Each layer (window, circularly polarizing plate, touch sensor) forming the flexible laminate for an image display device and a film member (linearly polarizing plate, λ/4 retardation plate, or the like) constituting each layer may be bonded to each other via an adhesive layer formed of an adhesive.

Examples of the adhesive include general-purpose adhesives such as aqueous adhesives, organic solvent adhesives, solventless adhesives, solid adhesives, solvent-volatile adhesives, moisture-curable adhesives, heat-curable adhesives, anaerobic curable adhesives, active energy ray-curable adhesives, curing agent-mixed adhesives, hot-melt adhesives, pressure-sensitive adhesives (pressure-sensitive adhesives), and remoistenable adhesives. Among them, water-based adhesives, solvent-volatile adhesives, active energy ray-curable adhesives, and adhesives are generally used.

The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive strength, and is preferably 0.01 to 500 μm, and more preferably 0.1 to 300 μm. When the laminate for a flexible image display device has a plurality of adhesive layers, the thickness and type of each adhesive layer may be the same or different.

The water-based adhesive is an adhesive mainly containing water, and a polyvinyl alcohol polymer, a water-soluble polymer such as starch, or a water-dispersed polymer such as an ethylene-vinyl acetate emulsion or a styrene-butadiene emulsion can be used as a main polymer. In addition to water and the main agent polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be added.

In the case of bonding with an aqueous solvent volatile adhesive, adhesiveness can be provided by injecting the aqueous solvent volatile adhesive between the layers to be bonded, bonding the layers to be bonded, and then drying the layers.

The thickness of the adhesive layer when an aqueous adhesive is used is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. When an aqueous adhesive is used for the plurality of adhesive layers, the thickness and type of each adhesive layer may be the same or different.

The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material, which is irradiated with an active energy ray to form an adhesive layer. The active energy ray-curable composition may contain at least 1 polymer of a radical polymerizable compound and a cation polymerizable compound.

Specific examples of the radical polymerizable compound and the cation polymerizable compound described here are the same as those contained in the hard coat composition described above. Among them, a radical polymerizable compound is preferably used. In particular, as the radical polymerizable compound contained in the active energy ray-curable adhesive used for forming the adhesive layer, a compound having an acryloyl group is preferably used. In addition, in order to reduce the viscosity of the active energy ray-curable adhesive itself, it is preferable to include a monofunctional compound as the radical polymerizable compound.

The cationic polymerizable compound is the same as the compound described in the hard coat composition.

Among them, as the cationically polymerizable compound used in the active energy ray-curable adhesive, an epoxy compound is preferably used. In addition, in order to reduce the viscosity as the adhesive composition, it is preferable to include a monofunctional compound as the reactive diluent.

The active energy ray-curable adhesive may further contain a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and they can be appropriately selected and used according to the kind of the polymerizable compound. Specific examples of the radical polymerization initiator, the cationic polymerization initiator, and the radical and cationic polymerization initiators include those similar to those described in the polymerization initiator contained in the hard coat composition.

The active energy ray-curable composition may further contain an ion scavenger, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoaming agent solvent, an additive, a solvent, and the like. In the case of using an active energy ray-curable adhesive, the adhesive can be bonded by applying an active energy ray-curable composition to one or both of the adhesive layers, bonding the adhesive layers, and irradiating active energy rays through one or both of the adhesive layers to cure the adhesive layers. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm. When a multilayer active energy ray-curable adhesive is used, the thickness and type of each layer may be the same or different.

The pressure-sensitive adhesive may be classified into, for example, an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, and the like, depending on the type of the base polymer. The laminate for a flexible image display device may be used for bonding the layers of the laminate. The binder may further contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like in addition to the main polymer.

The adhesive layer bonding layer is formed by dissolving and dispersing each component constituting the adhesive in a solvent to obtain an adhesive composition, applying the adhesive composition onto a substrate, and drying the adhesive composition. The adhesive layer formed of the adhesive composition may be formed by directly applying the adhesive composition to an adherend, or by transferring an adhesive composition separately formed on a substrate.

In addition, a release film is preferably used to cover the pressure-sensitive adhesive surface before bonding.

When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 500 μm, more preferably 1 to 300 μm. When a multilayer adhesive is used, the thickness and type of each layer may be the same or different.

(light-shielding pattern)

The light shielding pattern may be applied as at least a part of a bezel or a housing of the flexible image display device. The wiring disposed at the edge of the flexible image display device is hidden by the light-shielding pattern and is hard to be viewed, thereby improving the visibility of the image.

The light blocking pattern may be in the form of a single layer or a plurality of layers. The color of the light-shielding pattern is not particularly limited, and the light-shielding pattern has various colors such as black, white, and metallic colors. The light-shielding pattern may be formed of a pigment for color development, and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. In addition, they can be used alone or in a mixture of 2 or more.

The light shielding pattern can be formed by various methods such as printing, photolithography, and inkjet. The thickness of the light-shielding pattern is preferably 1 to 100 μm, and more preferably 2 to 50 μm. Further, the light-shielding pattern may be given a shape such as an inclination in the thickness direction thereof.

The film thickness of the above-described film, functional layer, device, and the like can be measured by a general film thickness measuring method. Examples of the film thickness measuring method include a method using a cross-sectional observation using an electron microscope, a method using a level difference detector, a film thickness measuring method using an optical interference method such as spectroscopic interference method or laser interference method, and a film thickness measuring method using spectroscopic ellipsometry.

< laser processing device >

Fig. 2 is a perspective view showing an example of the laser processing apparatus 30 used in the dicing step of the present embodiment.

The laser processing apparatus 30 shown in fig. 2 includes a laser irradiation apparatus (irradiation tool) 31 for irradiating a polarizing plate FX with laser light L, a laser scanning apparatus (scanning tool) 32 for scanning the laser light L along a cutting line C of the polarizing plate FX, and a drive control apparatus (drive control tool) 33 for controlling the drive of each part.

Fig. 3 is a perspective view showing a specific configuration of the laser irradiation device 31.

The laser irradiation device 31 shown in fig. 3 includes a 1 st laser light source 34A that emits a 1 st laser light L1, a 2 nd laser light source 34B that emits a 2 nd laser light L2, a dichroic mirror (optical path switching means) 35 that transmits or reflects the 1 st laser light L1 and the 2 nd laser light L2 and emits the 1 st laser light L1 and the 2 nd laser light L2 in the same direction, a condensing lens (condensing optical system) 36 that condenses the 1 st laser light L1 and the 2 nd laser light L1 onto a polarizing plate FX, and 1 st and 2 nd position adjusting mechanisms 37A and 37B (position adjusting means) that are disposed on an optical path between the dichroic mirror 35 and the condensing lens 36 and adjust irradiation positions of the 1 st laser light L1 and the 2 nd laser light L2 that irradiate the polarizing plate FX.

In the laser processing apparatus 30 shown in fig. 2, the 1 st laser light L1 and the 2 nd laser light L2 having different wavelengths are collectively described as the laser light L, and in the following description, the 1 st laser light L1 and the 2 nd laser light L2 are collectively described as the laser light L without making any special distinction.

The 1 st laser light source 34A outputs the 1 st laser light L1 by pulse oscillation, the 2 nd laser light source 34B outputs the 2 nd laser light L2 having a wavelength different from that of the 1 st laser light L1 by pulse oscillation, and specifically, in the present embodiment, carbon dioxide (CO) is used₂) As the 1 st laser light source 34A, a YAG laser oscillator was used as the 2 nd laser light source 34B. in this case, the 1 st laser light L1 was an infrared laser light having a wavelength of 9.4 μm, and the 2 nd laser light L2 was an ultraviolet laser light having a wavelength of 266 nm.

As the 2 nd laser source 34B, an excimer laser oscillator (ultraviolet laser having a wavelength of 157 to 351 nm), a semiconductor laser (L D: L aser Diode) excited solid-state pulse laser oscillator (infrared laser having a wavelength of 2940 nm), a pulse fiber laser oscillator (infrared laser having a wavelength of 3 μm), a CO pulse laser oscillator (infrared laser having a wavelength of 5.5 μm), or the like can be used.

The dichroic mirror 35 transmits one laser beam (1 st laser beam L1 in the present embodiment) of the 1 st laser beam L1 and the 2 nd laser beam L2 having different wavelengths from each other, and reflects the other laser beam (2 nd laser beam L2 in the present embodiment).

When the arrangement of the 1 st laser light source 34A and the 2 nd laser light source 34B is reversed, a dichroic mirror that reflects the 1 st laser light L1 (one laser light) and transmits the 2 nd laser light L2 (the other laser light) may be used as the dichroic mirror 35, and a dichroic prism may be used instead of the dichroic mirror 35.

The condenser lens 36 is formed of, for example, an f θ lens having a function of correcting the scanning speed of the laser light L (L1, L2) to be constant.

The 1 st and 2 nd position adjusting mechanisms 37A and 37B are formed by, for example, a current mirror, and have a function as a scanner (scanning tool) capable of two-axis scanning of the laser beam L (L1 and L2) in a plane parallel to the polarizing plate FX.

Specifically, the 1 st position adjustment mechanism 37A includes a mirror 38a that reflects the laser beam L (L1, L2) toward the 2 nd position adjustment mechanism 37B, and an actuator 39a that adjusts the angle of the mirror 38a, and the mirror 38a is attached to a rotation shaft 40a of the actuator 39a that is rotatable about the Z axis.

On the other hand, the 2 nd position adjustment mechanism 37B includes a mirror 38B for reflecting the laser beam L (L1, L2) reflected by the mirror 38a of the 1 st position adjustment mechanism 37A toward the condenser lens 36, and an actuator 39B for adjusting the angle of the mirror 38B, and the mirror 38B is attached to a rotation shaft 40B of the actuator 39B rotatable about the Y axis.

In the 1 st and 2 nd position adjusting devices 37A and 37B, the irradiation position of the laser beam L (L1 and L2) irradiated to the polarizing plate FX can be adjusted by biaxial scanning by adjusting the angles of the mirrors 38a and 38B while controlling the driving of the actuators 39a and 39B by the drive control device 33 described later.

For example, in the 1 st and 2 nd position adjusting mechanisms 37A and 37B, by adjusting the irradiation position of the laser light L (L1 and L02) irradiated to the polarizing plate FX, the laser light L1 (L1 and L2) indicated by a solid line in fig. 3 can be condensed at the condensed point Qa on the polarizing plate FX, the laser light L (L1 and L2) indicated by a one-dot chain line in fig. 3 can be condensed at the condensed point Qb on the polarizing plate FX, and the laser light L (L1 and L2) indicated by a two-dot chain line in fig. 3 can be condensed at the condensed point Qc on the polarizing plate FX.

As shown in fig. 2, the laser scanner 32 includes a slider mechanism (not shown) using, for example, a linear motor, and the laser irradiation device 31 can be moved in the width direction (X-axis direction) V1 of the polarizing plate FX, the longitudinal direction (Y-axis direction) V2 of the polarizing plate FX, and the thickness direction (Z-axis direction) V3 of the polarizing plate FX under the control of a drive controller 33 described later.

The laser scanning device 32 is not limited to the operation of moving the laser irradiation device 31, and may move the polarizing plate FX itself, and in this case, the laser L (L1, L2) from the laser irradiation device 31 may be scanned (traced) along the cutting line C of the polarizing plate FX, or both the laser irradiation device 31 and the polarizing plate FX may be moved.

The drive control device 33 is electrically connected to the 1 st and 2 nd laser light sources 34A and 34B included in the laser irradiation device 31, and controls the drive of the 1 st and 2 nd laser light sources 34A and 34B, specifically, the drive control device 33 switches the drive (ON/OFF) of the 1 st laser light source 34A and the 2 nd laser light source 34B, and the drive control device 33 controls the power and the number of pulse oscillations of the laser light L (L1 and L2) emitted from the 1 st and 2 nd laser light sources 34A and 34B.

Thereby, the 1 st laser L1 and the 2 nd laser L2 can be selectively irradiated to the polarizing plate FX, and in addition, the energy amount per unit area of the laser light L (L1, L2) irradiated to the polarizing plate FX can be variably adjusted.

The drive controller 33 is electrically connected to the laser scanner 32 and controls the moving speed of the laser scanner 32, thereby variably adjusting the energy amount per unit area of the laser beam L (L1, L2) irradiated to the polarizing plate FX while variably adjusting the scanning speed of the laser beam L (L1, L2).

The drive control unit 33 is electrically connected to the 1 st and 2 nd position adjusting mechanisms 37A and 37B included in the laser irradiation device 31, and controls the drive of the 1 st and 2 nd position adjusting mechanisms 37A and 37B, whereby the irradiation position of the laser beam L (L1 and L2) irradiated to the polarizing plate FX can be adjusted by biaxial scanning.

< cutting Process of polarizing plate >

From the viewpoint of exhibiting the effect of the present invention, it is particularly preferable that the laminated film cut by the cutting method of the present invention contains at least a layer containing a cycloolefin polymer such as a COP layer.

In the case where a cutting method generally used in film cutting, such as a cutting method by a carbon dioxide laser, is used for the COP layer, a cut surface having a good finish state as described above cannot be obtained. In contrast, when the cutting method of the present invention is applied to a laminated film including a COP layer, particularly a polarizing plate including a COP layer, a significant effect can be obtained.

Specifically, as a method for cutting a laminated film to which the present invention is applied, a step of cutting the polarizing plate FX using the laser processing apparatus 30 will be described with reference to fig. 4(a) and (b). Fig. 4(a) and (b) are cross-sectional views showing the cutting process of polarizing plate FX in this order.

In this embodiment, a description will be given of a cutting process of a polarizing plate (laminated film) in which a TAC layer, a PVA layer (film-type polarizer layer), and a COP layer are sequentially laminated as the polarizing plate FX.

When the polarizing plate FX is cut by the laser processing apparatus 30, first, as shown in fig. 4(a), the 1 st laser light L1 is scanned along the cutting line C of the polarizing plate FX while the 1 st laser light L1 is irradiated to the polarizing plate FX (referred to as the 1 st scanning.) the cutting line C may be set on the polarizing plate FX so that a single sheet of a desired size can be obtained after cutting.

At this time, the upper-layer-side protective layer (TAC layer) S4 and the polarizer layer (PVA layer) S5, which show photodecomposition reaction due to absorption of the 1 st laser light L1, among the layers S3, S5, and S4 constituting the polarizing plate FX, are cut by the 1 st laser light L1. in the 1 st scan by the 1 st laser light L1, it is preferable that the focal position U1 of the 1 st laser light L1 is set to a position deeper than the polarizer layer (PVA layer) S5.

Thus, the polarizing plate FX has a slit V along the cutting line C. The groove V is cut to a depth that intercepts the upper-layer-side protective layer (TAC layer) S4 and the polarizer layer (PVA layer) S5.

Then, as shown in fig. 4(b), while irradiating the polarizing plate FX with the 2 nd laser light L2, the 2 nd laser light L2 is scanned along the cutting line C of the polarizing plate FX (referred to as the 2 nd scan).

At this time, the lower protective layer (COP layer) S3 showing photodecomposition reaction due to absorption of the 2 nd laser light L2 among the layers S3, S5, S4 constituting the polarizing plate FX is cut with the 2 nd laser light L2 in the 2 nd scanning with the 2 nd laser light L2, it is preferable that the focal position U2 of the 2 nd laser light L2 is set at a deeper position than the lower protective layer (COP layer) S3.

Thus, the notch V is formed to be deeper in the depth direction from the position where the polarizer layer (PVA layer) S5 is cut, and to be deeper than the protective layer (COP layer) S3 on the lower layer side. However, in the present cutting process, polarizing plate FX may be cut along cutting line C by the 2 nd pass.

Fig. 5 shows transmittance of "COP", "PVA", "TAC", and "PET", which are constituent materials of the protective layer S3 on the lower layer side, the polarizer layer S5, the protective layer S4 on the upper layer side, and the surface protective film S2, for light having a wavelength of 2.0 to 14.0 μm. The COP is shown in FIG. 6, where transmittance for light having a wavelength of 200 to 500 μm is shown.

As shown in fig. 5, it is understood that COP shows substantially no light absorption (transmittance is substantially 100%) with respect to 1 st laser L1 (carbon dioxide laser) having a wavelength of 9.4 μm, and PVA, TAC, and PET other than COP show a certain degree of light absorption, while, as shown in fig. 6, COP shows a certain degree of light absorption with respect to 2 nd laser L2 (YAG laser, fourth high frequency) having a wavelength of 266 nm.

Therefore, when the polarizing plate FX is intended to be cut only by the 1 st laser L1, the upper protective layer (TAC layer) S4 and the polarizer layer (PVA layer) S5 are layers that are easily cut (layers having a high absorptivity of the 1 st laser L1), and therefore are cut by photodecomposition processing with less heat generation, whereas the lower protective layer (COP layer) S3 is a layer that is difficult to cut (layer having a low absorptivity of the 1 st laser L1), and therefore, the cross-sectional quality is deteriorated by thermal processing cutting by molecular vibration.

In contrast, in the cutting method to which the present invention is applied, the upper protective layer (TAC layer) S4 and the polarizer layer (PVA layer) S5 are cut with the 1 st laser L1, and the lower protective layer (COP layer) S3 is cut with the 2 nd laser L2 in this case, since any of the layers S3, S5, and S4 are cut with photodecomposition processing in which heat generation is small, a cut surface in a finished state can be obtained in the polarizing plate FX after cutting.

In the case where the polarizing plate FX is cut only with the 2 nd laser L2, the polarizing plate FX is cut by the photodecomposition process with less heat generation, but the processing speed is significantly slow because the laser power is weak, and thus the cutting method with only the 2 nd laser L2 is industrially inefficient.

As described above, in the cutting method of the present embodiment, by cutting the polarizing plate FX by the photodecomposition process with little heat generation using the 1 st and 2 nd laser beams L1, L2 having different wavelengths, the polarizing plate FX. can be cut with high accuracy along the cutting line C, and the cut surface of the polarizing plate FX can be finished well without damaging the polarizing plate FX, so that the method can be applied to further narrowing the frame of the display region of the optical display device.

(other embodiments)

The present invention is not necessarily limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

Specifically, in the cutting step, for example, the polarizing plate FX may be cut by using a laser processing apparatus 30A shown in fig. 7, instead of the laser processing apparatus 30 shown in fig. 2. Fig. 7 is a perspective view showing the structure of the laser processing apparatus 30A. In the following description, the same parts as those of the laser processing apparatus 30 are not described, and the same reference numerals are used in the drawings.

< laser processing device >

The laser processing apparatus 30A shown in fig. 7 includes a 1 st laser irradiation device 31A for irradiating a 1 st laser L1 and a 2 nd laser irradiation device 31B for irradiating a 2 nd laser L2, in place of the above-described laser irradiation device 31, and in other words, the laser processing apparatus 30A includes the 1 st laser irradiation device 31A having the 1 st laser source 34A and the 2 nd laser irradiation device 31B having the 2 nd laser source 34B separately.

When the 1 st laser irradiation device 31A and the 2 nd laser irradiation device 31B are separately provided, the 1 st and 2 nd laser irradiation devices 31A and 31B may be configured such that the dichroic mirror 35 is omitted from the configuration of the laser irradiation device 31 and the 1 st or 2 nd laser light L1 or L2 is emitted from the 1 st or 2 nd laser light sources 34A and 34B toward the 1 st position adjustment mechanism 37A.

The 1 st laser irradiation device 31A and the 2 nd laser irradiation device 31B are respectively moved and operated by the laser scanning device 32, and are respectively drive-controlled by the drive control device 33.

When the polarizing plate FX is cut by using the laser processing apparatus 30A shown in fig. 7, first, the 1 st laser irradiation apparatus 31A scans the 1 st laser light L1 along the cutting line C of the polarizing plate FX while irradiating the 1 st laser light L1 to the polarizing plate FX.

Thus, the protective layer (TAC layer) S4 and the polarizer layer (PVA layer) S5 on the upper layer side among the layers S3, S5, S4 constituting the polarizing plate FX are cut by the 1 st laser L1.

Then, the 2 nd laser irradiator 31B scans the 2 nd laser light L2 along the cutting line C of the polarizing plate FX while irradiating the 2 nd laser light L2 to the polarizing plate FX.

In this way, the lower protective layer (COP layer) S3 among the layers S3, S5, S4 constituting the polarizing plate FX is cut by the 2 nd laser L2, and therefore, in the cutting step, the polarizing plate FX can be cut along the cutting line C by the 2 nd scanning similarly to the case where the laser processing apparatus 30 shown in fig. 2 is used.

In the case of using the laser processing apparatus 30A shown in fig. 7, the 2 nd laser beam L2 can be scanned by the 2 nd laser irradiation apparatus 31B while following the scanning of the 1 st laser beam L1 by the 1 st laser irradiation apparatus 31A, and therefore, in the case of using the laser processing apparatus 30A shown in fig. 7, the cutting of the polarizing plate FX can be performed at a higher speed than in the case of using the laser processing apparatus 30 shown in fig. 2.

Further, the sheet cut out from the polarizing plate FX according to the embodiment of the present invention may be further laminated with a retardation film, a brightness enhancement film, or the like by providing a new adhesive layer by applying an adhesive to the lower protective layer (COP layer) S3 and laminating the sheet to the liquid crystal panel through the adhesive layer.

For example, a polarizing plate FX' shown in fig. 8 has a structure in which a surface protective film (PET film) S2 is bonded to each of both surfaces of a lower protective layer (COP layer) S3 and an upper protective layer (TAC layer) S4, which sandwich a polarizer layer (PVA layer) S5, so as to be freely separable.

< cutting Process of polarizing plate >

The cutting process of the polarizing plate FX' using the laser processing apparatus 30 will be described with reference to fig. 9(a) to (c). Fig. 9(a) to (c) are cross-sectional views showing the cutting step of polarizing plate FX' in this order.

When the polarizing plate FX' is cut by the laser processing apparatus 30, first, as shown in fig. 9(a), the 1 st laser light L1 is scanned along the cutting line C of the polarizing plate FX while the 1 st laser light L1 is irradiated to the polarizing plate FX (referred to as the 1 st scanning).

At this time, the upper layer side surface protection film (PET layer) S2, the upper layer side protection layer (TAC layer) S4, and the polarizer layer (PVA layer) S5, which show photodecomposition reaction due to absorption of the 1 st laser light L1 among the layers (films) S2, S3, S5, S4, and S2 constituting the polarizing plate FX', are cut by the 1 st laser light L1. in the 1 st scanning by the 1 st laser light L1, the focal position U1 of the 1 st laser light L1 is preferably set to a position deeper than the polarizer layer (PVA layer) S5.

Thus, the polarizing plate FX 'has a cut groove V' along the cutting line C. The dicing groove V' is formed to a depth that cuts the upper surface protective film (PET film) S2, the upper protective layer (TAC layer) S4, and the polarizer layer (PVA layer) S5.

Then, as shown in fig. 9(b), while irradiating the polarizing plate FX 'with the 2 nd laser light L2, the 2 nd laser light L2 is scanned along the cutting line C of the polarizing plate FX' (referred to as 2 nd scan).

At this time, the lower protective layer (COP layer) S3 showing photodecomposition reaction due to absorption of the 2 nd laser light L2 among the layers (films) S2, S3, S5, S4, and S2 constituting the polarizing plate FX' is cut by the 2 nd laser light L2. in the 2 nd scanning by the 2 nd laser light L2, it is preferable to set the focal position U2 of the 2 nd laser light L2 at a position deeper than the lower protective layer (COP layer) S3.

Thereby, the cut groove V' is formed at a depth of the protective layer (COP layer) S3 on the lower layer side further in the depth direction from the position of the cut polarizer layer (PVA layer) S5.

Then, as shown in fig. 9(C), while irradiating the polarizing plate FX 'with the 1 st laser light L1, the 1 st laser light L1 is scanned along the cutting line C of the polarizing plate FX' (referred to as the 3 rd scan).

At this time, the surface protection film (PET film) S2 on the lower layer side showing photodecomposition reaction due to absorption of the 1 st laser light L1 among the layers (films) S2, S3, S5, S4, and S2 constituting the polarizing plate FX' is cut by the 1 st laser light L1, and in the 3 rd scan by the 1 st laser light L1, the focal position U3 of the 1 st laser light L1 is preferably set to a deeper position than the surface protection film (PET film) S2 on the lower layer side.

Thus, the dicing groove V' is formed at a depth of the surface protection film (PET film) S2 from the position of the protective layer (COP layer) S3 on the lower layer side in the depth direction. Therefore, in this cutting process, polarizing plate FX' can be cut along cutting line C by the 3 rd pass.

As described above, in the cutting method of the present embodiment, by using the 1 st and 2 nd laser beams L1, L2 having different wavelengths, the polarizing plate FX 'is cut by photodecomposition processing with little heat generation, and the polarizing plate FX' can be cut with high precision along the cutting line C.

In the present embodiment, although the above-described 1 st laser L1 is used for the 3 rd laser beam when the 3 rd laser beam is used as the laser beam used in the 3 rd scan, a laser beam having a wavelength different from that of the 1 st and 2 nd laser beams L1 and L2 may be used as long as the surface protective film (PET film) S2 on the lower layer side can be cut by photodecomposition reaction, and the same applies to the 4 th and subsequent scans.

That is, in the cutting method of the laminated film to which the present invention is applied, a laser having a wavelength capable of cutting by the light decomposition reaction may be appropriately selected and used in accordance with a resin layer to be cut among a plurality of resin layers constituting the laminated film.

The method of cutting the laminated film to which the present invention is applied is not limited to the case of cutting the polarizing plates FX and FX' described above, and the present invention can be widely applied to a cutting step of cutting a laminated film in which a plurality of resin layers having different materials are laminated.

In the method for producing a laminated film to which a plurality of resin layers having different materials are laminated, the present invention can be widely applied to the method for producing a laminated film including the above-described dicing step.

The laminated film produced by applying the present invention may include optical films such as retardation films and brightness enhancement films in addition to the polarizing plates FX and FX' described above, and the dicing method of the present invention may be applied to the case where the laminated film in which these optical films are laminated is diced.

In addition, as a method of scanning the laser beam with respect to the dicing line, there may be mentioned a method of repeatedly scanning the laser beam in one direction along the dicing line, a method of repeatedly scanning the laser beam back and forth between the start point and the end point of the dicing line, and a method of simultaneously scanning a plurality of laser beams L along the dicing line.

Description of the symbols

30 laser processing apparatus, 31 laser irradiation apparatus (irradiation means), 32 laser scanning apparatus (scanning means), 33 drive control apparatus (drive control means), 34A 1 st laser light source, 34B 2 nd laser light source, 35 dichroic mirror (optical path switching means), 36 condenser lens (condensing optical system), 37A 1 st position adjusting mechanism, 37B 2 nd position adjusting mechanism, FX 'polarizing plate (laminated film), S2 surface protective film (PET film), protective layer (COP layer) on the S3 lower layer side, protective layer (TAC layer) on the S4 upper layer side, S5 polarizing plate layer (PVC layer), L laser, L1 st laser light (3 rd laser light), L2 nd laser light, C cut line, U1, U2, U3 focal position, V, V' cut groove.

Claims (8)

1. A method for cutting a laminated film, which comprises cutting a laminated film in which a plurality of resin layers having different materials are laminated along a cutting line,

the plurality of resin layers are cut by scanning a cutting line of the laminated film with a plurality of laser lights having different wavelengths.

2. The method for cutting a laminated film according to claim 1,

scanning a cutting line of the laminated film with a 1 st laser and a 2 nd laser having a different wavelength from the 1 st laser, thereby cutting a resin layer showing a photodecomposition reaction due to absorption of the 1 st laser among the plurality of resin layers with the 1 st laser, and cutting a resin layer showing a photodecomposition reaction due to absorption of the 2 nd laser among the plurality of resin layers with the 2 nd laser.

3. The method for cutting a laminated film according to claim 1 or 2,

the 1 st laser is laser excited by a carbon dioxide laser,

the 2 nd laser is laser excited by a YAG laser, an excimer laser or a semiconductor laser.

4. A method for producing a laminated film, characterized by laminating a plurality of resin layers of different materials,

the manufacturing method includes a cutting process of cutting the plurality of resin layers along a cutting line,

the cutting method according to any one of claims 1 to 3 is used in the cutting step.

5. The method for manufacturing a laminated film according to claim 4,

the laminated film is a polarizing plate in which at least a COP layer as a cycloolefin polymer layer and a PVA layer as a polyvinyl alcohol layer are laminated,

cutting the PVA layer using the 1 st laser,

cutting the COP layer with the 2 nd laser.

6. The method for manufacturing a laminated film according to claim 5,

the laminated film further includes a TAC layer which is a polarizing plate in which the COP layer, the PVA layer and the TAC layer are sequentially laminated,

cutting the TAC layer and the PVA layer by the 1 st laser,

cutting the COP layer with the 2 nd laser.

7. The method for manufacturing a laminated film according to claim 5,

the 2 nd laser is laser excited by a YAG laser, an excimer laser or a semiconductor laser.

8. The method for manufacturing a laminated film according to claim 4,

the laminated film is a laminated film for an image display device, which includes at least 2 or more of flexibility selected from a circularly polarizing plate, a window film, and a touch sensor.

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