TWI666474B - Method for producing a protection-film-attached optical film - Google Patents

Abstract

The present invention provides a method for manufacturing an optical film with a protective film, which includes a step of attaching a protective film on the surface of the optical film, and an optical film with a protective film obtained by the step of attaching the protective film. The peeling force of the protective film at both ends in the width direction with respect to the optical film is improved compared to other parts of the optical film with the protective film. This manufacturing method preferably further includes a step of removing both ends in the width direction after the step of bonding the protective film.

Description

Method for manufacturing optical film with protective film

The present invention relates to a method for manufacturing an optical film with a protective film, which is formed by layering a protective film on an optical film surface area, and more particularly to the method for manufacturing an optical film as a polarizing plate.

An optical film used for an image display device such as a liquid crystal display device is sometimes a laminated film composed of a plurality of films. For example, a polarizing plate, which is a type of optical film, generally has an optical film with a protective film laminated on one or both sides of the polarizing film that is an optical film, and further laminated optical films with other optical functions if necessary. Composition. The polarizing plate is generally a long laminated film (polarizing plate) obtained by laminating other raw material films continuously rolled out from the film roll by continuously laminating raw material films continuously rolled and transported from the film roll. It is rolled into a roll shape, that is, it is manufactured by a roll-to-roll method.

In a roll-to-roll optical film manufacturing method, when an optical film such as a polarizing plate for manufacturing a long strip is rolled up, in order to protect the surface of the optical film, it is generally performed by the same method before the winding. Roller-to-roller peelable protective film (also known as surface protection) Film), and is wound in the form of an optical film with a protective film (for example, Japanese Patent Application Laid-Open No. 2008-275722 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2012-121269 (Patent Document 2)). This protective film is a film for temporary protection on the surface of an optical film product. For example, when the image display device is assembled (more specifically, after the optical film with the protective film is attached to the image display element), it is peeled off. Remove.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-275722

[Patent Document 2] Japanese Patent Laid-Open No. 2012-121269

As described above, since the protective film is accompanied by a peeling step of peeling and removing it from the optical film, it is required to have an antistatic property useful for preventing the generation of static electricity during peeling. In addition, in order to improve the antistatic performance and at the same time facilitate the peeling step, low adhesion to the optical film (low peeling force of the protective film from the optical film) is also required. However, the lower density of the protective film has caused a new problem called "floating". In this specification, the term "floating" refers to the width direction of the optical film with a protective film when it is manufactured, or when the manufactured optical film with a protective film is rolled and stored / carried in the form of a roller. At the end, the protective film is partially peeled from the surface of the optical film, and at this part, the protective film is in a floating state. When such a "floating" occurs in an optical film with a protective film, for example, the optical film with a protective film is passed through a clamp in a later step. In the case of a nip roll, the air that has penetrated into the "floating" part may be squeezed and compressed between the nip rolls, and the compressed air may cause stripe marks on the optical film to be of poor quality.

Here, an object of the present invention is to provide a method for manufacturing an optical film with a protective film, which can suppress the protective film not only during the production of the optical film with a protective film (especially when the optical film is a polarizer) "Floating" problem, and in the peeling step of the protective film, the low adhesion of the protective film to the optical film is also achieved, and the protective film can be easily peeled and removed.

This invention provides the manufacturing method of the optical film with a protective film shown below.

[1] A method for manufacturing an optical film with a protective film, comprising a step of attaching a protective film on the surface of the optical film, wherein the optical film with a protective film obtained by the step of attaching the protective film is The peeling force of the protective film with respect to the optical film at both ends in the width direction is improved compared to other portions of the optical film with the protective film.

[2] The manufacturing method according to [1], further comprising a step of removing both ends in the width direction after the step of bonding the protective film.

[3] The manufacturing method according to [1] or [2], which further includes a step of performing a corona treatment before the step of bonding the protective film to increase the peeling force.

[4] The manufacturing method according to [3], wherein the corona The treatment is performed on the optical film.

[5] The manufacturing method according to any one of [1] to [4], wherein a peeling force of the protective film from the optical film is 0.09 N / 25 mm or more at both ends in the width direction.

[6] The manufacturing method according to [1] or [2], wherein the protective film includes an adhesive layer adhered to the surface and a substrate film supporting the adhesive layer, and by using the adhesive The adhesive force of the portions constituting the two ends in the width direction of the layer is improved as compared with other portions to increase the peeling force.

[7] The manufacturing method according to any one of [1] to [6], wherein the optical film is a polarizing plate.

According to the present invention, a method for manufacturing an optical film with a protective film can be provided, which can be suppressed not only when the optical film with a protective film is manufactured or when the manufactured optical film with a protective film is rolled up and stored / rolled in a roll form The problem of "floating" of the protective film, and at the same time in the peeling step of the protective film, the low adhesiveness of the protective film to the optical film is also achieved, and the protective film can be easily peeled and removed.

That is, according to the present invention, since the adhesiveness between the optical film and the protective film is improved at both ends in the width direction, when manufacturing the optical film with the protective film, specifically, at the time of bonding the protective film, Later, when the optical film with a protective film is wound up, and when it is stored / transported in a roll state, the "floating" problem of the protective film can be suppressed, and the above-mentioned quality defects can also be suppressed. In addition, during the period until the peeling step of the protective film is performed, if the If the optical film with a protective film having improved adhesion at both ends in the width direction is removed in advance in the both ends in the width direction, the protective film can be peeled and removed relatively easily in the above-mentioned peeling step. The present invention is particularly effective for a polarizing plate that is prone to poor quality due to "floating" of a protective film.

1. 1'‧‧‧ polarizing plate with protective film

10, 10’‧‧‧ polarizing plate

20, 20’‧‧‧ protective film

100‧‧‧Polarizer

200‧‧‧The first protective film

300‧‧‧ 2nd protective film

400‧‧‧ Adhesive layer

500‧‧‧ isolation film

A‧‧‧ Both ends of the polarizing plate with protective film in the width direction

Figures 1 (a) to (c) are schematic diagrams showing a method for manufacturing a polarizing plate with a protective film according to the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of a layer configuration of a polarizing plate.

FIG. 3 is a schematic plan view for explaining the evaluation method for floating.

In the following, the present invention will be described in more detail by taking the case where the optical film is a polarizing plate as an example, but the present invention is not limited to this example, and the following description will be applied to the case where the optical film is a polarizing plate as an example. Other optical films. Other optical films may be single-layer films or multilayer films.

Referring to FIG. 1, the manufacturing method of the protective film-attached polarizing plate of the present invention is characterized by the steps of attaching the protective film 20 to the surface of the polarizing plate 10 [FIG. 1 (a) and (b)]. The protective film 20 with respect to the polarizing plate 10 in the width direction ends A of the protective film-attached polarizing plate 1 obtained from the step of attaching the protective film 20 is compared with the other portions of the polarizing plate 1 with the protective film. For those who improve. By controlling the peeling force so as to increase the peeling force at both end portions A in the width direction, bonding the polarizing plate 10 and the protective film 20 can suppress the above-mentioned "floating" problem and further effectively suppress the above-mentioned quality defects. This feature is based on the need to suppress The idea that the peeling force (adhesiveness) of the entire bonding interface between the polarizing plate 10 and the protective film 20 can be increased by only increasing the peeling force at both ends A in the width direction, and the review results supporting this idea.

In addition, in this way, the polarizing plate 1 with a protective film that enhances the peeling force not only for the entire area of the above-mentioned bonding interface but only for both ends A in the width direction can be removed by so-called The protective film-attached polarizing plate 1 'formed by the polarizing plate 10' and the protective film 20 'from which both ends A in the width direction have been removed is easily obtained with simple steps [FIG. 1 (c)]. In the protective film-attached polarizing plate 1 ′, the peeling step in the protective film 20 ′ (for example, the peeling step after attaching the protective film-attached polarizing plate 1 ′ and the image display element) can be relatively easily performed. The protective film 20 'is peeled and removed, so that the antistatic performance of the polarizing plate 1' with a protective film can be improved, and the ease of implementation of the peeling step can be improved. Increasing the peeling force and setting the width direction both ends A to be removed outside the effective width range of the polarizing plate 1 with a protective film will not reduce the yield of the polarizing plate 1 'with a protective film.

Hereinafter, an embodiment is shown and the manufacturing method of the polarizing plate with a protective film of this invention is demonstrated in detail. A plurality of embodiments shown below are different in a specific method for improving the peeling force in the width direction both ends A of the polarizing plate 1 with a protective film.

<First Embodiment>

The method for manufacturing a polarizing plate with a protective film according to this embodiment includes the following steps in order: the warranty obtained in order to attach the protective film 20 to the surface of the polarizing plate 10 The peeling force of the protective film 20 on the polarizing plate 10 at both ends A in the width direction of the protective film is improved compared to other parts of the polarizing plate 1 with a protective film, and the surface is applied to the bonding surface. A step of activating treatment, and a step of attaching a protective film 20 on the surface of the polarizing plate 10.

As described above, it is preferable that the step of attaching the protective film 20 further includes a step of removing both ends A in the width direction.

Each step will be described below.

(1) Steps for surface activation treatment

〔Polarizer〕

The layer structure of the polarizing plate 10 used in this step is not particularly limited as long as it includes a polarizer, but usually includes a polarizer and a protective film laminated on at least one side thereof. A protective film can also be laminated on the two areas of the polarizer. The protective film is usually laminated and bonded to a polarizer through an adhesive layer.

The polarizing plate 10 may include a layer (or film) other than a polarizer and a protective film. For example, in general, polarizing plates are circulated on the market, and most of them are polarizing plates with an adhesive layer on an outer area of the polarizing plate, which is useful for bonding an image display element (such as a liquid crystal cell) or other optical components with an adhesive layer. The polarizing plate 10 used in the present invention may also include such an adhesive layer. When the adhesive layer is included, it is usually a separator on the outer area of the adhesive layer to protect the surface (outside) of the adhesive layer.

In addition, the protective film of the polarizing plate 10 may be provided with a surface treatment such as a hard coat layer, an anti-glare layer, an anti-reflection layer, an anti-static layer, and an anti-fouling layer on the outside (the surface opposite to the polarizer). Layer (coated layer) By. Further, the polarizing plate 10 may include a layer or film having optical functions other than a polarizer. One example is a retardation film.

An example of the layer structure of the polarizing plate 10 is shown in FIG. The polarizing plate 10 shown in FIG. 2 includes: a polarizer 100; a first protective film 200 adhered to one side of the polarizer 100; a second protective film 300 adhered to the other side of the polarizer 100; and laminated on the second An adhesive layer 400 on the outer surface of the protective film 300; an isolation film 500 laminated on the outer surface of the adhesive layer 400. Not only the polarizer 100 and the protective film (the first protective film 200, the second protective film 300), but also the layer structure of the adhesive layer 400 and the release film 500 is also a preferred layer structure of the polarizing plate 10 used in the present invention one.

The polarizing film 100 is an optical film having the property of absorbing linearly polarized light having a vibration plane having a parallel optical axis and penetrating linearly polarized light having a vibration plane having a vertical optical axis. Polyvinyl alcohol resin film. As the dichroic pigment, iodine and a dichroic organic dye can be used. The polyvinyl alcohol-based resin constituting the polarizer 100 may be, in addition to polyvinyl alcohol, a saponified product of polyvinyl acetate, vinyl acetate and other monomers copolymerizable therewith (e.g., ethylene and unsaturated carboxylic acid). Etc.) saponified vinyl alcohol copolymers. The thickness of the polarizer 100 is usually about 5 to 40 μm.

The polarizing film 100 can include a step of uniaxially stretching the polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye. A pigmented polyvinyl alcohol-based resin film is prepared by a method of treating a boric acid aqueous solution and a step of washing with a boric acid aqueous solution after the treatment. Made. Dyeing of a dichroic dye can be performed by immersing a film in an aqueous solution containing a dichroic dye, and treatment by a boric acid solution can be performed by immersing a film in an aqueous solution of boric acid.

The uniaxial extension of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic pigment. When the one-axis extension is performed after dyeing, the one-axis extension may be performed before or during the boric acid treatment. Furthermore, one-axis extension may be performed in the plural stages of these.

The first and second protective films 200 and 300 may be thermoplastic resin films having translucency (preferably optically transparent). Specific examples of the thermoplastic resin include polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); polyester resins (poly Ethylene terephthalate resins, etc.); (meth) acrylic resins (methacrylic methyl resins, etc.); cellulose resins (such as cellulose triacetate, cellulose diacetate cellulose acetate) Resin, etc.); Polycarbonate resin; Polyvinyl alcohol resin; Polyvinyl acetate resin; Polyarylate resin; Polystyrene resin; Polyether fluorene resin; Polyfluorene resin; Polyamine resin Resins; polyimide-based resins; and mixtures and copolymers thereof. The thickness of the first and second protective films 200 and 300 is, for example, about 5 to 200 μm, preferably 10 to 150 μm, and more preferably 15 to 100 μm. In the present specification, "(meth) acrylfluorenyl" means at least one selected from acrylfluorenyl and methacrylfluorenyl.

As shown in the example in FIG. 2, when the first protective film 200 is provided on one side of the polarizer 100 and the second protective film 300 is provided on the other side, the first protective film 200 and the second protective film 300 can be heated by the same kind The plastic resin may be composed of different types of thermoplastic resins.

The polarizer 100, the first protective film 200, and the second protective film 300 can be bonded through an adhesive layer. As the adhesive for forming the adhesive layer, an aqueous adhesive (that is, one in which the adhesive component is dissolved or dispersed in water) or an active energy ray-curable adhesive can be used.

The adhesive component of the water-based adhesive may be, for example, a polyvinyl alcohol resin or a urethane resin. The active energy ray-curable adhesive may be, for example, a curable composition containing an active energy ray-curable compound such as an epoxy-based compound or a (meth) acrylic compound and a polymerization initiator. The active energy ray-curable adhesive may be a solventless adhesive, or may include an organic solvent. If a solventless adhesive is used, a drying process for removing the solvent is not required. When an active energy ray-curable adhesive is used, after the protective film is pasted through the adhesive layer, active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams are irradiated, preferably ultraviolet rays, to cure the adhesive layer. Therefore, in this case, the adhesive layer in the polarizing plate 10 is composed of a cured product of an active energy ray-curable adhesive.

As shown in the example in FIG. 2, when the first protective film 200 is provided on one surface of the polarizer 100 and the second protective film 300 is provided on the other surface, the first adhesive layer and the first protective film 200 are bonded together. The second adhesive layer combined with the second protective film 300 may be formed of the same type of adhesive, or may be formed of different types of adhesives, but from the viewpoint of manufacturing efficiency, it is preferably formed of the same type of adhesives. .

The adhesive layer 400 can be used to attach a protective film to an image display element (such as a liquid crystal cell) or other optical components. The light plate includes the adhesive constituting the adhesive layer 400, and examples thereof include (meth) acrylic adhesives, urethane adhesives, polysiloxane adhesives, polyester adhesives, polyamide adhesives, and polyacrylates. Ether-based adhesives, fluorine-based adhesives, rubber-based adhesives, and the like. Among them, (meth) acrylic adhesives are preferably used from the viewpoints of transparency, adhesion, reliability, and reworkability. The thickness of the adhesive layer 400 is usually 2 to 40 μm.

The barrier film 500 is provided for the purpose of temporarily protecting the adhesive layer 400 when storing, transporting, and inspecting a polarizing plate with a protective film. The isolation film 500 of the protective adhesive layer 400 is, for example, peeled off immediately before the polarizing plate with the protective film is attached to an image display element or other optical member.

The release film 500 is generally composed of a thermoplastic resin film subjected to a release treatment on one side, and the release treatment surface is adhered to the adhesive layer 400. The thermoplastic resin constituting the separator 500 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate and polyethylene naphthalate. Resin, etc.

The layer configuration of the polarizing plate 10 used in this step is not limited to the example shown in FIG. 2, and it may be, for example, the following layer configuration.

a) Omitting the isolation film 500, or omitting the configuration of the adhesive layer 400 and the isolation film 500, b) omitting the configuration of either the first protective film 200 and the second protective film 300, c) used as the second protective film 300 Optical compensation like retardation film The structure of the compensation film, d) In addition to the first protective film 200 and the second protective film 300, it also has a configuration of an optical compensation film such as a retardation film.

One example of the above b) is to omit the structure of the second protective film 300, and a suitable specific example is to directly laminate the adhesive layer 400 on the surface of the polarizer 100 opposite to the first protective film 200 to become the first protective film 200 / polarizer 100 / adhesive layer 400 / separator film 500.

A suitable specific example of the above c) is a layer constitution of the first protective film 200 / the polarizer 100 / the retardation film (the second protective film 300) / the adhesive layer 400 / the release film 500. A suitable specific example of the above d) is a layer constitution of the first protective film 200 / the polarizer 100 / the second protective film 300 / the retardation film / the adhesive layer 400 / the release film 500. At this time, the second protective film 300 and the retardation film can be bonded through an adhesive layer, for example.

The retardation film is an optical film having optical anisotropy such as one axis or two axes. For example, the retardation film may be a stretched film of a thermoplastic resin. In addition to the thermoplastic resins exemplified above for the first and second protective films 200 and 300, polydifluoroethylene / polymethyl methacrylate copolymer, liquid crystal polyester, cellulose acetate, Saponification of ethylene-vinyl acetate copolymer, polyvinyl chloride, etc. The stretching ratio is usually about 1.01 to 6 times.

〔Protective film〕

The protective film 20 attached to the polarizing plate 10 is a temporarily bonded film for protecting the surface of the polarizing plate. Generally, for example, after a polarizing plate with a protective film is attached to an image display element or other optical member, together with it The adhesive layer is peeled and removed together.

The protective film 20 may include a base film made of a thermoplastic resin and an adhesive layer provided on one side thereof. The thermoplastic resin constituting the substrate film may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. Resin, etc. Regarding the adhesive layer included in the protective film 20, the description of the aforementioned adhesive layer 400 is used. The protective film 20 is bonded to the surface of the polarizing plate 10 through the adhesive layer.

〔Surface activation treatment〕

The surface activation treatment performed before the step of bonding the protective film 20 on the surface of the polarizing plate 10 may be a corona treatment, a plasma treatment, an ultraviolet irradiation treatment, a flame (flame) treatment, a saponification treatment (such as Soaking of alkaline aqueous solution of sodium or potassium hydroxide). Among them, since it can be implemented relatively easily, and the effect of improving the peeling force (adhesion) of the protective film 20 to the polarizing plate 10 is also good, it is preferable to use corona treatment and plasma treatment, and more preferably to use corona. deal with. For example, when the corona treatment is performed, the larger the corona discharge amount, the higher the peeling force tends to be. The amount of corona discharge is usually 10W‧min / m ² or more. To improve the peeling force and effectively suppress the occurrence of "floating", it is preferably 15W‧min / m ² or more. In addition, the upper limit of the amount of corona discharge is usually 80 W‧min / m ² or less.

The surface activation treatment is performed only on the bonding surface portions of the polarizing plate 1 with a protective film obtained by bonding the protective film 20 to the polarizing plate 10 to be included in both ends A in the width direction. Thereby, the polarizing plate 1 with a protective film with the peeling force of the both ends A of the width direction higher than the other part of the polarizing plate 1 with a protective film can be obtained. In this way, Although the peeling force is higher than that of the other parts of the polarizing plate 1 with a protective film, since the other parts are not subjected to a surface activation treatment, in other words, it can be said that the peeling force at the both ends A in the width direction is higher than that of the untreated surface The situation (partially) of the activation treatment is further improved.

In addition, in an embodiment, the protective film 20 composed of a base film and an adhesive layer provided on one side of the protective film 20 has a width smaller than that of the base film, and both ends of the protective film 20 are not formed. The base film portion of the adhesive layer. When such a protective film 20 is used, both ends A in the width direction of the polarizing plate 1 with a protective film refer to both ends of the base film and the polarizing plate bonded through the adhesive layer, and do not include the above-mentioned non-adhesion. Substrate film part of the agent layer. The part of the substrate film is not bonded to the polarizing plate, and the "floating" problem will not occur in the first place.

The surface activation treatment is preferably performed on at least the bonding surface portion of the polarizing plate 10 side to be included in the both end portions A in the width direction. For example, when corona treatment is used, it was unexpectedly found that even if corona treatment is performed on the bonding surface portion of the protective film 20 side to be included in both ends A in the width direction, the tendency to increase the peeling force cannot be confirmed. Therefore, the bonding surface portion to which the corona treatment is performed preferably includes at least the bonding surface portion on the polarizing plate 10 side to be included in the both end portions A in the width direction.

The width of both end portions A in the width direction subjected to the surface activation treatment is not particularly limited as long as the adhesiveness sufficiently suppressing "floating" is obtained, and each single end portion is, for example, 1 mm or more, and preferably 5 mm or more. The upper limit of the width is not particularly limited, and although it is also affected by the width of the polarizing plate 1 with a protective film, each individual end may be, for example, 25 mm or less, It is preferably 15 mm or less.

In order to effectively suppress "floating", the peeling force at both ends A in the width direction is preferably 0.09 N / 25 mm or more, and more preferably 0.1 N / 25 mm or more. When the peeling force is less than 0.09 N / 25 mm, the adhesiveness at the both end portions A in the width direction becomes insufficient, and there is a concern that "floating" cannot be effectively suppressed. Moreover, the peeling force at the both ends A in the width direction is usually 0.20 N / 25 mm or less. When the peeling force exceeds 0.20N / 25mm, there is a concern that it is not easy to perform the peeling step and the productivity is reduced. The measurement method of the peeling force is based on the description of the example item mentioned later.

The surface activation treatment can be performed continuously on the raw material film (the polarizing plate 10 and / or the protective film 20) that is continuously conveyed. More specifically, for example, in the case of a corona treatment, a corona discharge device may be provided in advance at positions of both ends of the polarizing plate 10 in the width direction on the transportation path of the long polarizing plate 10 that is continuously conveyed. While continuously carrying the polarizing plate 10, corona treatment is continuously performed on both ends in the width direction of the polarizing plate 10 passing through the corona discharge device.

In general, a polarizing plate with a protective film obtained in the state of a long object is used to adjust the width in the width direction to a desired value, or to remove parts that are difficult to use in terms of quality and appearance in terms of products. Both ends in the width direction are cut and removed. More typically, not only in the width direction, but also in the length direction, they are cut to adjust to a desired value, and formed into a sheet to be bonded to an image display element or the like. Such a long polarizing plate with a protective film generally has an effective width (actually used as a product width), and both ends in the width direction outside the effective width range are excluded. The width direction both end portions A in which the peeling force is improved are preferably provided in the width direction both end portions outside the effective width range. Accordingly, when the step of removing both end portions A in the width direction is performed, even if this step is performed, the reduction in the yield of the polarizing plate 1 'with a protective film can be prevented.

(2) Steps of attaching the protective film 20

Bonding of the protective film 20 to the polarizing plate 10 can be performed by a conventionally known method. For example, the surface of the long polarizing plate 10 that is continuously conveyed (for example, if the polarizing plate is corona-treated on both ends in the width direction, the surface on the side where the corona-treatment is performed is used. ), A long protective film 20 that is also continuously conveyed is arranged, and the laminated body is continuously laminated with the protective film 20 by applying pressure from above and below with a laminating roller. The polarizing plate 1 with a protective film shown in FIG. 1 (b) can be obtained through this step. The obtained long polarizer 1 with a protective film can be wound into a roll shape.

According to the method of the present invention that further enhances the peeling force of both end portions A in the width direction, when manufacturing the polarizing plate 1 with a protective film, specifically, when the protective film 20 is bonded to the polarizing plate 10, after bonding, The problem of "floating" of the protective film 20 can be effectively suppressed when the polarizing plate 1 of the protective film is rolled up and when it is stored / transported in a roll state.

(3) Step of removing both ends A in the width direction

In this step, if the both ends A in the width direction of the polarizing plate 1 with a protective film having an improved peeling force are cut and removed, a polarizing plate with a protective film capable of peeling and removing the protective film 20 ′ can be obtained more easily. 1 '[Figure 1 (c)]. For cutting, a conventionally known cutting (cutting) means such as a shear cutter can be used. As described above, the width of the polarizing plate 1 with the protective film can be removed. At the same time, both ends of the sheet are cut in the longitudinal direction to obtain a polarizing plate 1 'with a protective film on a sheet having a desired size.

The cutting width at the time of cutting and removing both ends in the width direction of the polarizing plate 1 with a protective film is not particularly limited as long as the portion removed by cutting includes the entire width direction both ends A in the peeling force. Usually, a polarizing plate 1 'with a protective film having an effective width is produced by cutting and removing.

<Second Embodiment>

The method for manufacturing a polarizing plate with a protective film in this embodiment includes the following steps in order: preparing a protective film 20 having an adhesive force at a portion constituting both ends A in the width direction of the adhesive layer which is improved compared to other portions. And a step of laminating the protective film 20 on the surface of the polarizing plate 10.

That is, compared with the first embodiment described above, the surface activation treatment is performed in order to increase the peeling force of both ends A in the width direction of the polarizing plate 1 with a protective film, and the purpose of this embodiment is to increase the width in both directions. The peeling force of the end portion A is a protective film 20 having an improved adhesive force of the adhesive layer at a portion corresponding to both end portions A in the width direction. Those with ordinary knowledge in the technical field can easily understand that by this method, a polarizing plate 1 with a protective film having improved peeling force only at both ends A in the width direction can also be obtained, and can be used in the same manner as the first The same effect is achieved in the embodiment.

The step of attaching the protective film 20 and the step of removing both end portions A in the width direction, which are preferably successively implemented, are the same as the first embodiment described above, and the description in the first embodiment is cited.

The protective film 20 used in this embodiment is the same as the first embodiment described above, and may include a base film made of a thermoplastic resin and an adhesive layer provided on one side thereof. The adhesive layer of the protective film 20 used in this embodiment can be formed by separately applying adhesive compositions having different adhesive forces from each other. Specifically, the adhesive layer can be provided in the width direction of the polarizing plate 1 corresponding to the protective film. The portion A at both ends is composed of an adhesive layer X composed of an adhesive composition having a higher adhesive force, and an adhesive layer Y composed of an adhesive composition having a lower adhesive force provided on the other portions. .

Methods for increasing the adhesive force of the adhesive composition include, for example, increasing the molecular weight of the resin component in the adhesive composition (for example, (meth) acrylic polymer if it is a (meth) acrylic adhesive). Method, or a method of adding a tackifier resin to the adhesive composition.

[Example]

Hereinafter, examples and comparative examples are shown to further specifically describe the present invention, but the present invention is not limited to these examples. In the following examples, the peeling force of the protective film from the polarizing plate in the polarizing plate with a protective film was measured according to the following method.

(Peel force of protective film)

A test piece having a size of 25 mm × 150 mm was cut out of the obtained long polarized plate with a protective film from the widthwise end portion of the bonding interface including the corona treatment. At this time, the test piece was cut out so that the short-side direction was parallel to the longitudinal direction of the long polarizing plate with a protective film. Next, the release film was peeled from the test piece, and it was bonded to the glass substrate using the adhesive layer which the test piece had. Next, fix the polarizer side of the test piece while using the island The AGS-D type testing machine manufactured by Tsusho Seisakusho Co., Ltd. peeled the protective film from the polarizing plate at a peeling angle of 180 ° and a peeling speed of 300 mm / min, and measured the peeling force (unit: N / 25 mm).

<Example 1>

[1] Fabrication and surface activation of polarizing plates

The long raw film is continuously rolled up and conveyed from the film roll, and continuous production of the long polarizing plate 10 having the layer structure shown in FIG. 2 is performed. The layer structure of the polarizing plate 10 is a first protective film 200 (TAC film) with a thickness of 60 μm / a polarizer 100 with a thickness of 25 μm (adsorbed and aligned with an iodine-extended polyvinyl alcohol film) / a second protective film 300 with a thickness of 50 μm (ring Retardation film made of a polyolefin resin) / adhesive layer 400 ((meth) acrylic adhesive layer) with a thickness of 20 μm / separation film 500 (poly-p-phenylene with a release treatment on one side) Ethylene dicarboxylate film). Both the first protective film 200 and the second protective film 300 are ultraviolet-curing adhesives that are cured by an active energy ray-curable adhesive (a curable compound containing a cationic polymerizable epoxy-based compound and a photocationic polymerization initiator). An adhesive layer made of a hardened product of "ADEK Corporation" (KR-70T)) is bonded to the polarizer 100. The width of the polarizing plate 10 is 1330 mm. The effective width of the polarizing plate 10 is 1250 mm, so the width of the end portion outside the effective width range becomes 40 mm at each single end portion.

Subsequently, the polarizing plate 10 obtained as described above was continuously transported, and two corona discharge devices were used to corona-treat both ends in the width direction of the outer surface of the first protective film 200. From the effective width of the polarizing plate 10, the width of the widthwise end portion and each of the two end portions after corona treatment are within a range of about 15 mm outside the effective width (the outside is not more than The adhesive layer of the protective film 20 is present, and the area where the adhesive layer is not adhered), and the corona discharge amount is set to 73 W · min / m ² .

〔2〕 Lamination of protective film to polarizing plate

A long protective film 20 (formed by a (meth) acrylic adhesive layer and a polyethylene terephthalate film, thickness 53 μm) is continuously unwound and transported from a film roll, and is disposed at the same time as [1] The outer surface of the first protective film 200 of the obtained polarizing plate 10 after the corona treatment was laminated with a protective film 20 through a laminating roller to continuously manufacture a long polarizing plate with a protective film.

<Examples 2 to 3>

A polarizing plate with a protective film was obtained in the same manner as in Example 1 except that the amount of corona discharge was as shown in Table 1.

<Comparative example 1>

A polarizing plate with a protective film was obtained in the same manner as in Example 1 except that corona treatment was not performed on both ends of the protective film 20 in the width direction of the polarizing plate 10. In addition, "Pf" in Table 1 means a protective film.

<Comparative example 2>

A polarizing plate with a protective film was obtained in the same manner as in Example 1 except that the corona treatment was not performed.

About the polarizing plate with a protective film obtained by the Example and the comparative example, the peeling force of the protective film was measured according to the said method. The results are shown in Table 1. In addition, the polarizing plate with a protective film obtained in the examples and comparative examples was evaluated for the presence or absence of floating in accordance with the following procedure, and the size of the polarizing plate when floating occurred. The results are shown in Table 1.

(Floating evaluation)

Referring to FIG. 3, a test piece having a size of 700 mm × 1330 mm was cut out of the obtained polarizing plate with a protective film. At this time, the test piece was cut out so that the short-side direction was parallel to the longitudinal direction of the long polarizing plate with a protective film. The long-side direction (1330 mm) of the test piece was parallel to the width direction of the polarizing plate 10 and was the same width as the width of the polarizing plate 10. The “one end surface of the polarizing plate with a protective film” described in FIG. 3 refers to the end surface of the adhesive layer of the protective film 20. While visually confirming the presence or absence of the float of the obtained test piece, the float was evaluated by using the "loft invasion degree L" defined as the distance from the inner end of the float to the effective end as an index. size. The smaller L is, the larger the float is evaluated.

In Examples 1 to 3, no floating was recognized in the long polarized plate with the protective film and the test piece before the test piece was cut out. On the other hand, in Comparative Examples 1 and 2, both ends of the long polarizing plate with a protective film before cutting of the test piece were recognized as floating almost in the entire length direction, even when cut out at an arbitrary position. In each of the above test pieces, about 20 floats were recognized in Comparative Examples 1 and 2. The floating invasion L shown in Table 1 is the maximum of about 20 floating.

The optical film with a protective film has been described above as an example of a polarizing plate with a protective film, but it can also be expected to be stored and transported in the state of a roll when the optical film other than the polarizing plate is wound up. In this case, the problem of "floating" of the protective film can be suppressed, thereby suppressing the above-mentioned poor quality. In addition to the protective film, other optical films include films having optical functions such as a retardation film, a brightness enhancement film, an anti-glare film, a light diffusion film, and a polarizer.

Claims (7)

A method for manufacturing an optical film with a protective film includes a step of bonding a protective film on the surface of the optical film, wherein the optical film with a protective film obtained by the aforementioned step of bonding a protective film is in a width direction thereof. The peeling force of the protective film on the optical film at both ends is improved compared to the other portions of the optical film with the protective film. The manufacturing method according to item 1 of the scope of patent application, further comprising the step of removing both ends in the width direction after the step of bonding the protective film. The manufacturing method according to item 1 or 2 of the scope of patent application, which further includes a step of performing a corona treatment before the step of attaching the protective film to increase the peeling force. The manufacturing method according to item 3 of the scope of patent application, wherein the corona treatment is performed on the optical film. The manufacturing method according to item 1 or 2 of the scope of patent application, wherein the peeling force of the protective film from the optical film is 0.09 N / 25 mm or more at both ends in the width direction. The manufacturing method according to item 1 or 2 of the scope of the patent application, wherein the protective film comprises an adhesive layer adhered to the surface and a base film supporting the adhesive layer, and by using the adhesive layer The adhesive force of the portions constituting the both ends in the width direction is improved as compared with other portions to increase the peeling force. The manufacturing method according to item 1 or 2 of the scope of patent application, wherein the optical film is a polarizing plate.