TWI681032B - Surface-protective film for transparent conductive film, and transparent conductive film using the same - Google Patents

Abstract

The present invention provides a surface-protective film for a transparent conductive film in which an adhesive layer maintains smoothness of the surface, which has excellent handling properties even when attached on the transparent conductive film, which improves defects in appearance arising from the surface-protective film in the production and manufacturing and processing steps of the transparent conductive film, and which has good productivity in transparent electrode manufacturing steps for a touch panel and a transparent conductive film using the same. The present invention is a surface-protective film 5 for a transparent conductive film used by attached on the other surface of a transparent conductive film in which a transparent conductive film is formed on a surface of a resin film, wherein an adhesive layer 2 is laminated on one surface of a base film 1 by using an adhesive including an acrylic resin composition, a crosslinking agent, and a crosslinking catalyst, a storage modulus a of the adhesive layer at 30℃ is 4.0×10⁵ Pa or more and the adhesive powers a and b with respect to a PET film of the adhesive layer after aging for 5 days at 40℃ satisfy the relationship of 0.9

a/b

Description

Surface protective film for transparent conductive film and transparent conductivity using the protective film membrane

The present invention relates to a surface protective film for a transparent conductive film used for bonding to the other surface of a resin film having a transparent conductive film formed on one surface, and a transparent conductive film using the surface protective film. More specifically, the present invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. In the surface protective film for a transparent conductive film, the formed adhesive layer maintains the smoothness of the surface, Even if it is attached to the transparent conductive film, it has excellent handling properties. In the manufacturing and processing processes of the transparent conductive film, the appearance defects caused by the surface protective film are improved, and the transparent electrode manufacturing process for the touch panel The productivity in the is good.

Conventionally, in the technical fields of touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic ELs, solar cells, etc., transparent conductive films (hereinafter, sometimes referred to as "conductive films" ") is widely used for forming transparent electrodes. This transparent conductive film is formed with a transparent conductive film composed of, for example, ITO (indium tin oxide compound), AZO, or GZO (a compound in which aluminum or gallium is added to ZnO (zinc oxide)) on one surface of the substrate .

In addition, in the process of the transparent electrode for the touch panel, a variety of heating processes and reagent treatment processes are required. For example, the transparent conductive film formed with a transparent conductive film made of ITO, AZO, or GZO is annealed Crystallization process of metal oxide film, printing process of resist, etching process, process of forming circuit wiring using silver paste, printing process of insulating layer, punching process, etc. In the manufacturing process of such a transparent electrode, in order to prevent fouling and damage on the surface of the transparent conductive film opposite to the surface on which the transparent conductive film is formed, a surface protective film for a transparent conductive film is bonded and used.

In the manufacturing process of the transparent electrode, annealing treatment, formation of circuit wiring using silver paste, and the like are subjected to heat treatment at a temperature of about 150° C. Therefore, the protective film for a transparent conductive film is required to have heat resistance.

Various proposals have been made regarding protective films for transparent conductive films used in the production of transparent electrodes for touch panels and the like. For example, Patent Document 1 proposes a surface protective film for a transparent conductive film, which is provided with an adhesive layer on a single surface of a substrate made of a thermoplastic resin film having a melting point of 200° C. or higher. Some people think that it has better heat resistance than a surface protective film for a transparent conductive film using a polyolefin resin such as polyethylene or polypropylene as a base material.

In addition, Patent Document 2 proposes a method for manufacturing a surface protective film for a transparent conductive film, in which a base film containing polyethylene terephthalate resin and/or polyethylene naphthalate resin is After coating the adhesive on one side, at the specified temperature. Residence time. Dry with tensile tension. After the surface protective film for a transparent conductive film obtained by this manufacturing method is bonded to the transparent conductive film, even if it undergoes a heating process, it does not cause a large curl.

Patent Document 3 proposes a transparent conductive film and protection A resin film of a film, wherein a transparent conductive film is provided on one surface of the resin film, and a protective film is provided on the surface of the resin film opposite to the surface on which the transparent conductive film is provided, the protective film being composed of a first film and a second film And the first film and the second film are sequentially arranged on the resin film. The heat shrinkage rate of the first film after heating at 150°C for 30 minutes is 0.5% or less in both MD and TD directions. The second film has the same The difference in linear expansion coefficient of the resin film with the transparent conductive film and the protective film is a linear expansion coefficient of 40 ppm/°C or less. If this invention is applied, a transparent conductive film free of dimensional changes and curling caused by heat treatment in processing processes such as touch panelization can be obtained.

In addition, Patent Document 4 proposes a table for a transparent conductive film The surface protection film uses a predetermined thickness and a bending-resistant peeling film to smooth the surface of the adhesive layer of the surface protection film and improve the appearance defects.

【Prior Art Literature】 【Patent Literature】

Patent Document 1: Japanese Patent Laid-Open No. 2003-170535

Patent Document 2: Japanese Patent No. 4342775

Patent Document 3: Japanese Patent Laid-Open No. 11-268168

Patent Document 4: Japanese Patent Laid-Open No. 2013-226676

The present invention provides a surface protective film for a transparent conductive film in which the adhesive layer of the surface protective film maintains the smoothness of the surface and the appearance defects are improved as in Patent Document 4. The surface protection film of Patent Document 4 is characterized by using a peeling film having a bending resistance of 0.30 mN to 40 mN at 40°C, but it has the bending resistance The flexible film has a problem that the thickness becomes thicker and the cost increases. In addition, when manufacturing the surface protection film or when the user uses the surface protection film, the winding diameter of the surface protection film may be limited depending on the specifications of the processing machine used. In this case, the surface protection film using the release film with a thick base material has the following problem compared to the surface protection film using the release film with a thin base material: rolling up with a predetermined winding diameter The winding length at the time becomes shorter, and the productivity in the transparent electrode manufacturing process for touch panels decreases.

The present invention has been completed in view of the above circumstances, and its object is to provide Provided is a surface protective film for a transparent conductive film and a transparent conductive film using the same. The surface protective film for a transparent conductive film is in a state of being rewound from a drum, and the adhesive for the surface protective film for a transparent conductive film The layer maintains the smoothness of the surface and has excellent handleability even when it is bonded to the transparent conductive film. In the manufacturing and processing processes of the transparent conductive film, the appearance defects due to the surface protection film for the transparent conductive film are obtained Improvement, and good productivity in the transparent electrode manufacturing process for touch panels.

The surface protective film for a transparent conductive film is manufactured by applying an adhesive on a base film or a release film, and after evaporating the solvent in the adhesive during the drying process, bonding the release film or the base film, and Roll into a roll shape. The inventors conducted intensive studies and found that the cured state of the adhesive layer 15 minutes after the start of drying is related to the uneven deformation of the surface of the adhesive layer. Furthermore, it was found that by using an adhesive layer that cures within 15 minutes after the start of drying, even when a release film with a thin substrate thickness is used for the adhesive application of the adhesive layer of the surface protective film for a transparent conductive film In the case of the present invention, it is also possible to suppress the deformation of the surface of the adhesive layer to be adhered to the adherend, resulting in uneven deformation, thereby completing the present invention.

In the process of surface protection film, the adhesive is usually applied on the base film and dried to form an adhesive layer, and then cured in the state of the roll, but during this curing period, due to the roll of the roll The peeling film is deformed due to tight influence. Therefore, when the adhesive layer is cured after the peeling film is deformed, the surface shape of the peeling film is transferred to the surface of the adhesive layer, which will become the appearance of the transparent conductive film after the transparent conductive film is manufactured and processed. The reason for the deterioration.

The technical idea of the present invention is as follows: while the surface protective film for a transparent conductive film is cured in a roll shape, the adhesive layer is cured before the peeling film is deformed, thereby suppressing the peeling film from being deformed Deformation of the surface of the adhesive layer to maintain smoothness.

That is, while the surface protective film for a transparent conductive film according to the present invention is cured in a roll shape, the adhesive layer to which the release film is bonded is pulled before being deformed by the deformation of the release film, and then bonded The curing of the adhesive layer prevents unevenness on the surface of the adhesive layer attached to the adherend, thereby maintaining smoothness.

The inventors found that the state of curing of the adhesive layer can be grasped by comparing the force of the adhesive layer 15 minutes after the start of drying of the adhesive layer and the completion of the aging (aging). More specifically, if 15 minutes after the drying of the adhesive layer starts and the ratio of the adhesive force of the adhesive layer to the PET film after the aging (curing) is completed (the adhesive force after the aging is completed divided by 15 minutes after the start of drying) The value obtained by the adhesive force) is within a predetermined range, even if the peeling film with a thin base material is used for the bonding application of the adhesive layer of the surface protective film for the transparent conductive film In this case, it is possible to suppress deformation of the surface of the adhesive layer to be bonded to the adherend.

In order to solve the above problems, the present invention provides the following surface protective film for a transparent conductive film.

A surface protective film for a transparent conductive film, which is applied to the other surface of a resin film having a transparent conductive film formed on one surface, and is characterized in that the surface protective film for a transparent conductive film is on a base film An adhesive layer is laminated on one side of the adhesive layer. An acrylic adhesive containing an acrylic resin composition, a crosslinking agent and a crosslinking catalyst is used for the adhesive layer. The storage modulus of the adhesive layer at 30°C is 4.0 ×10 ⁵ Pa or more, and the adhesive force of the adhesive layer to the PET film 15 minutes after the drying of the adhesive layer starts and the adhesion of the adhesive layer to the PET film after aging at 40°C for 5 days The force satisfies the relationship of the following formula (1).

a/b

2.0 式(1) 0.9

a/b

2.0 Formula (1)

(Here, a is the adhesive force of the adhesive layer to the PET film 15 minutes after the drying of the adhesive layer starts, and b is the adhesive force of the adhesive layer to the PET film after aging at 40°C for 5 days. Adhesion)

In addition, the present invention provides a transparent conductive film obtained by laminating the above-mentioned surface protective film for a transparent conductive film to the other surface of a resin film having a transparent conductive film formed on one surface .

The present invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. The surface protective film for a transparent conductive film of the present invention maintains the formed adhesive layer in a state of being rewound from the drum The smoothness of the surface, even when attached to a transparent conductive film, also has excellent handling properties, in In the manufacturing process of the transparent conductive film, defects in appearance defects caused by the surface protective film are improved, and the productivity in the transparent electrode process for touch panels is good.

In addition, in recent years, with the thinning of the casing of high-function portable terminals such as smartphones, the thinning of the transparent conductive films used has continued to progress. The surface protective film for a transparent conductive film of the present invention has a very small curl even after a heating process in the state of being attached to a thinned transparent conductive film in the process of a transparent electrode for a touch panel. Thereby, the workability and production efficiency of the manufacturing process of the transparent electrode for touch panels can be greatly improved.

1‧‧‧ Base film

2‧‧‧adhesive layer

3‧‧‧ peeling film

4‧‧‧ Adhesive film

5‧‧‧ Surface protective film for transparent conductive film

6‧‧‧Resin film

6a‧‧‧One side of resin film

6b‧‧‧The other side of the resin film

7‧‧‧Transparent conductive film

10‧‧‧Transparent conductive film

11‧‧‧Laminated film

21‧‧‧Drum for peeling film

22‧‧‧Roller for substrate film

23‧‧‧Binder coating device

24‧‧‧ drying oven

25, 26‧‧‧ pressure roller

27‧‧‧Roller for surface protective film for transparent conductive film

Fig. 1 is a cross-sectional view showing an example of the surface protective film for a transparent conductive film of the present invention.

[FIG. 2] A cross-sectional view showing an example of bonding the surface protective film for a transparent conductive film of the present invention to a transparent conductive film.

[FIG. 3] A schematic diagram showing an example of a method for manufacturing a surface protective film for a transparent conductive film of the present invention.

Hereinafter, the present invention will be described in detail based on the embodiments.

FIG. 1 is a cross-sectional view showing an example of the surface protective film for a transparent conductive film of the present invention. The surface protective film 5 for a transparent conductive film is laminated with an adhesive layer 2 on one side of a transparent flexible base film 1. The surface of the adhesive layer 2 to be bonded to the adherend is laminated with a peeling film 3 that has been peeled off to protect the surface of the adhesive layer through the peeled surface.

As the base film 1, a transparent plastic film having flexibility is used. Thus, it is possible to directly conduct conductivity in a state where the surface protective film for a transparent conductive film of the present invention is bonded and bonded to the other surface of the transparent conductive film on which the transparent conductive film is formed on one surface of the substrate Visual inspection of the membrane. Examples of the plastic film used as the base film 1 include polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate. Diester and other polyester films. In addition to the polyester film, as long as it is a plastic film having the required strength and having optical compatibility, other types of plastic films can also be used. The base film 1 is an unstretched film, a unidirectional or biaxially stretched film, etc., and is not particularly limited, but the base film preferably has a low heat shrinkage rate.

Moreover, the surface protection for transparent conductive films concerning this invention The thickness of the base film 1 of the film is not particularly limited, and may be selected according to the transparent conductive film used. In the case where the thickness of the transparent conductive film used is 100 μm or more, the handleability of the transparent conductive film itself is not too bad. Therefore, the surface protective film mainly focuses on protecting the surface of the transparent conductive film. Therefore, a surface protective film having a thickness of about 25 to 75 μm can be used for the base film 1 of the surface protective film.

On the other hand, the transparent conductive film used is as thin as 50 μm In the case below, the handleability of the transparent conductive film itself is poor. Therefore, the handleability of the surface protective film is also considered, and it is preferable to use a thick transparent conductive film of the base film. The specific thickness of the base film is preferably about 100 to 188 μm.

In addition, an adhesive layer may be laminated on the base film 1 as needed The anti-fouling layer, antistatic layer, oligomer prevention layer, hard coating to prevent damage, corona discharge treatment, anchor coating treatment, etc. are easy to bond Sexual treatment.

The adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention is preferably an acrylic adhesive. In particular, a two-component adhesive in which an acrylic adhesive and a cross-linking agent are prepared (mixed) immediately before use is preferred.

As the acrylic adhesive, a (meth)acrylic polymer (acrylic resin composition) to which a crosslinking agent is added and, if necessary, a tackifier is preferably added. (Meth)acrylic polymers are usually n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate and other main monomers and acrylonitrile, vinyl acetate, methyl methacrylate , Ethyl acrylate and other comonomers, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide and other functional monomers are copolymerized and The polymer. The monomer composition constituting the (meth)acrylic polymer is preferably 50% or more of the (meth)acrylic monomer, and the (meth)acrylic monomer may be 100%.

Examples of the crosslinking agent include isocyanate compounds, epoxy compounds, melamine compounds, and metal chelate compounds. Among them, isocyanate compounds are preferred. Further, a polyisocyanate compound having at least 2 or more than 3 isocyanate (NCO) groups in one molecule is preferable.

Although the polyisocyanate compound is classified into aliphatic isocyanate, aromatic isocyanate, acyclic isocyanate, and alicyclic isocyanate, it may be any one. Specific examples of the difunctional isocyanate compound include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). Compounds; methylene diphenyl diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (H6XDI), o- tolidine diisocyanate ( o- tolidine diisocyanate, TOID), toluene diisocyanate (TDI) and other aromatic isocyanate compounds.

Examples of trifunctional or higher isocyanate compounds include biuret-type modified products of diisocyanates (compounds having two NCO groups in one molecule), trimeric isocyanate-based modified products; and trimethylolpropane (TMP ), adducts (polyol-modified products) of trivalent or higher polyhydric alcohols (compounds having at least 3 or more OH groups in one molecule), etc.

Although the amount of crosslinking agent added considers (meth)acrylic polymers The kind, degree of polymerization, amount of functional groups, etc. may be determined, and are not particularly limited, but usually the crosslinking agent is about 0.5 to 10 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer.

Moreover, the surface protection for transparent conductive films concerning this invention When the film is cured in a roll shape, the adhesive layer needs to be cured before the peeling film is deformed. Therefore, in order to promote the crosslinking reaction between the (meth)acrylic polymer and the crosslinking agent, a crosslinking catalyst is added Better. The cross-linking catalyst may be any substance that acts as a catalyst for the reaction (cross-linking reaction) between the (meth)acrylic polymer and the cross-linking agent. When a polyisocyanate compound is used as the cross-linking agent, Organic compounds such as amine compounds such as tertiary amines, organic tin compounds, organic lead compounds, organic zinc compounds, organic iron compounds, etc.

Examples of the tertiary amine include trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, triethylenediamine, and morpholine derivatives , Piperazine derivatives, etc.

Examples of the organotin compound include dialkyltin oxide, fatty acid salts of dialkyltin, and fatty acid salts of stannous.

The amount of crosslinking catalyst added may be determined in consideration of the type, degree of polymerization, amount of functional groups, type of crosslinking catalyst, amount of addition, etc. of the (meth)acrylic polymer, although it is not particularly limited. 100 parts by weight, usually about 0.01 to 0.5 parts by weight.

In addition, in order to suppress the adhesive composition after the preparation of the crosslinking agent Excessive viscosity increase, gelation, and extended pot life of the adhesive composition may contain a cross-linking retarder as needed.

Examples of the crosslinking retarder include β-ketoacid such as methyl acetoacetate, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, and stearyl acetoacetate. Β-diketones such as esters, acetone, 2,4-hexanedione, acetophenone, etc. In particular, it is preferably at least one or more selected from the group consisting of acetone acetone and ethyl acetate. These crosslinking retarders are keto-enol tautomeric compounds. In the adhesive composition using the polyisocyanate compound as the crosslinking agent, by isolating the isocyanate group of the crosslinking agent, the crosslinking agent can be suppressed Excessive viscosity increase and gelation of the adhesive composition can extend the pot life of the adhesive composition.

Although the addition amount of the cross-linking retarder is not particularly limited, it is usually about 1.0 to 5.0 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer.

In addition, a tackifier can be added to the adhesive as needed. Make Examples of the viscosity-imparting agent include rosin, benzofuran-indene, terpenes, petroleum, and phenols.

In addition, the surface protection for the transparent conductive film according to the present invention In the adhesive layer 2 of the protective film, an antistatic agent may be mixed as needed. As the antistatic agent, an antistatic agent having good dispersibility in the (meth)acrylic polymer or good compatibility with the (meth)acrylic polymer is preferred. Examples of usable antistatic agents include surfactants, ionic liquids, alkali metal salts, metal oxides, metal fine particles, conductive polymers, carbon, and carbon nanotubes. From the viewpoints of transparency and affinity with (meth)acrylic polymers, surfactants, ionic liquids, alkali metal salts, and the like are preferred. The amount of antistatic agent added to the binder can be appropriately determined in consideration of the type of antistatic agent and the compatibility with the base polymer. In addition, the type and addition of the antistatic agent are specifically considered in consideration of the peeling voltage required when peeling the surface protective film for a transparent conductive film from the transparent conductive film, the contamination of the adherend, the adhesive strength, etc. the amount.

Moreover, the surface protection for transparent conductive films concerning this invention Although the thickness of the adhesive layer 2 of the film is not particularly limited, it is preferably about 5 to 50 μm, and more preferably about 5 to 30 μm. When the thickness of the adhesive layer 2 exceeds 50 μm, the cost of manufacturing the surface protective film for a transparent conductive film increases, which impairs competitiveness. When the thickness of the adhesive layer 2 is less than 5 μm, there is a problem that the adhesion to the transparent conductive film is reduced, or when foreign substances are mixed when the surface protective film is attached to the transparent conductive film, the transparent conductive The sex membrane is greatly deformed.

In addition, the adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention has a peeling strength to the surface of the adherend of about 0.05 to 0.5 N/25 mm, and a light adhesive micro-adhesive layer good. By forming a surface protective film for a transparent conductive film having such a micro-adhesive layer, excellent handleability that can be easily peeled off from the adherend can be obtained.

Moreover, the surface protection for transparent conductive films concerning this invention The material of the film release film 3 is not particularly limited. Examples of materials that can be used for the release film include polyolefin films such as polyethylene films, polypropylene films, and polymethylpentene films, and the use of polysiloxane-based release agents on the surfaces of films such as polyester films. A release film, a fluororesin film, a polyimide film, etc. which have undergone a peeling treatment. In addition, it may be a film in which a plurality of films are laminated using an adhesive, or a laminated film in which a resin is melt-extruded on a film and laminated. These single-layer films or laminated films are subjected to a peeling treatment using a peeling agent such as a polysiloxane-based peeling agent to obtain a peeling film.

Moreover, the surface protection for transparent conductive films concerning this invention The thickness of the peeling film 3 of the film is not particularly limited, and a peeling film of a thickness that is easy to use may be selected. Usually it is about 19μm~75μm release film.

When the peeling film 3 is thick, the total length of the surface protective film for a transparent conductive film is shortened and the manufacturing cost increases in a drum of the same winding diameter rolled into a drum shape. Therefore, it is necessary to guide the peeling film 3 to an appropriate thickness. In addition, the peeling film 3 is preferably a peeling film obtained by peeling a single-layer polyester film, and a peeling film obtained by subjecting a film formed by multi-layering a polyester film using an adhesive to a peeling process.

In addition, an adhesive layer 2 and a release film 3 are sequentially laminated on the base film 1 The method may be performed by a well-known method and is not particularly limited. Specifically, it may be a method in which the adhesive layer 2 is coated on the base film 1 and dried, and then the release film 3 is bonded, and the adhesive layer 2 is coated on the release film 3 and dried, and then the base film 1 is bonded. Any of the methods.

In addition, the formation of the adhesive layer on the base film 1 can be performed by a known method. Specifically, a reverse coating method, a comma coat method, a gravure printing method, a slit die coating method, and a Mayer bar coat can be used A well-known coating method such as a method, an anchor coat method, and the like.

In addition, a method of performing a peeling treatment on the peeling film 3 is known through Method can be carried out. Specifically, a peeling agent is applied on one side of the peeling film 3 by a coating method such as a gravure printing method, a Mayer bar coat method, an anchor coat method, and the like by heating or The release agent may be dried and cured by ultraviolet irradiation or the like. If necessary, the film to be subjected to the peeling treatment may be subjected to pretreatments such as corona treatment, plasma treatment, anchor coating and the like to improve the adhesion of the peeling agent to the film.

In addition, FIG. 2 shows the surface of the transparent conductive film of the present invention. A schematic configuration diagram of an example of the laminated film 11 in which the protective film is bonded to the transparent conductive film.

The laminated film 11 is a laminated film formed by bonding the adhesive film 4 to the surface of the transparent conductive film 10 with the adhesive layer 2 thereof. The adhesive film 4 is a surface protective film 5 for the transparent conductive film of the present invention. The peeling film 3 is peeled off. In the transparent conductive film 10, a transparent conductive film 7 is formed on one surface 6a of the resin film 6. The adhesive film 4 is bonded to the other surface 6b of the resin film 6.

Examples of the transparent conductive film 10 include a polyethylene terephthalate (PET) film formed with a transparent conductive film such as ITO, AZO, or GZO, and a ring formed with a transparent conductive film such as ITO, AZO, or GZO. Polyolefin film, etc. Such transparent conductive films are widely used in the formation of transparent electrodes in the technical fields such as touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic ELs, and solar cells.

The surface protective film for a transparent conductive film of the present invention exerts the following excellent effects: In the process of manufacturing a transparent electrode such as a touch panel, it is possible to greatly improve the operation Performance and production efficiency, even if it is a thin transparent conductive film, it will not reduce workability and handling.

In addition, FIG. 3 is a schematic diagram showing an example of a method for manufacturing a surface protective film for a transparent conductive film of the present invention.

The peeling film 3 and the base film 1 are repeatedly released from the drum 21 wound with the peeling film 3 and the drum 22 wound with the base film 1. On one surface of the base film 1, an adhesive is applied by an adhesive application device 23. The base film 1 coated with the adhesive is dried in the drying furnace 24 to form the adhesive film 4. The surface of the adhesive film 4 on which the adhesive layer was formed was opposed to the surface of the release film 3 subjected to the peeling treatment, and was pressure-bonded using pressure rollers 25 and 26 to obtain a surface protective film 5 for a transparent conductive film. The transparent conductive film surface protective film 5 is rolled up by the roller 27. Normally, the storage and transportation of the surface protective film 5 for a transparent conductive film are performed in the state of the drum 27. When bonding to the transparent conductive film 10, the surface protective film 5 for transparent conductive film is rewound from the drum 27.

【Example】

Hereinafter, the present invention will be further described based on examples.

(Production of surface protective film for transparent conductive film of Example 1)

On one side of the biaxially stretched polyester film with a thickness of 25 μm, a coating is applied by the Mel-Bar method to make the thickness of the dried polysiloxane film 0.1 μm. The coating is an addition reaction type Polysiloxane (manufactured by Toray Dow Corning, product name: SRX-211 with 100 parts by weight of platinum catalyst SRX-212 added with 1 part by weight) is a paint diluted with toluene/ethyl acetate 1:1 mixed solvent. Furthermore, drying and curing were carried out in a hot-air circulation type oven at a temperature of 120° C. for 1 minute to obtain the release film of Example 1.

In addition, the adhesive layer is formed using an adhesive composition, the adhesive The mixture composition is an HDI-based crosslinking agent (Japan Polyurethane Industry Co., Ltd.) added to 100 parts by weight of an acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate with a solid content of 40%. Manufactured, product name: CORONATEHX) 4 parts by weight, a crosslinking catalyst of 0.03 parts by weight of dibutyltin dilaurate and mixed to obtain a binder composition. The above-mentioned adhesive composition was coated on a polyethylene terephthalate film with a thickness of 125 μm, so that the thickness of the adhesive layer after drying was 20 μm, and the adhesive was applied in a hot air circulation oven at a temperature of 130°C. Dry for 1 minute. Then, the silicone-treated surface of the release film of Example 1 prepared above was laminated and laminated on the surface of the adhesive layer to obtain a surface protective film for a transparent conductive film of Example 1.

(Production of surface protective film for transparent conductive film of Example 2)

A surface protective film for a transparent conductive film of Example 2 was obtained in the same manner as in Example 1, except that the amount of the crosslinking agent added was 6 parts by weight relative to 100 parts by weight of the acrylic polymer.

(Production of surface protective film for transparent conductive film of Example 3)

A surface protective film for a transparent conductive film of Example 3 was obtained in the same manner as in Example 1, except that the amount of the crosslinking agent added was 8 parts by weight relative to 100 parts by weight of the acrylic polymer.

(Production of surface protective film for transparent conductive film of Comparative Example 1)

A surface protective film for a transparent conductive film of Comparative Example 1 was obtained in the same manner as in Example 1, except that the drying temperature of the adhesive layer was 100°C.

(Production of surface protective film for transparent conductive film of Comparative Example 2)

In addition to the use of 100 parts by weight of acrylic polymer copolymerized with butyl acrylate, 2-ethylhexyl acrylate and acrylic acid with a solid content of 40%, an epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name) is added : TETRAD-C) A binder composition obtained by mixing 4 parts by weight as a binder composition, in the same manner as in Example 1, a surface protective film for a transparent conductive film of Comparative Example 2 was obtained.

(Production of a surface protective film for a transparent conductive film of Comparative Example 3)

In addition to the use of 100 parts by weight of acrylic polymer copolymerized with 2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate and having a solid content of 40%, an HDI-based crosslinking agent (Japanese polyurethane) is added Manufactured by an industrial company, product name: CORONATE HX) 1 part by weight, 0.03 parts by weight of dibutyltin dilaurate as a crosslinking catalyst and mixed to obtain a binder composition as the binder composition, the same as Example 1 Method, a surface protective film for a transparent conductive film of Comparative Example 3 was obtained.

(Production of a surface protective film for a transparent conductive film of Comparative Example 4)

A surface protective film for a transparent conductive film of Comparative Example 4 was obtained in the same manner as in Example 1, except that dibutyltin dilaurate as a crosslinking catalyst was not added.

The method and test results of the evaluation test are shown below. Here, "hard coating PET film" is used as an example of the base material (film) for transparent conductive films.

(Determination of storage modulus)

For the samples obtained in Examples and Comparative Examples, the storage of the adhesive layer at 30°C after aging for 5 days in a 40°C environment was measured using a viscoelasticity measuring device (manufactured by ABM, dynamic viscoelasticity measuring device Reogel-E4000) Modulus.

(Determination of PET film adhesion)

For the samples obtained in the examples and comparative examples, the adhesion of the adhesive layer to the PET film was measured 15 minutes after the drying of the adhesive layer started and after aging for 5 days in an environment of 40°C.

The sample was attached to a biaxially stretched polyethylene terephthalate film (made by Mitsubishi Resin Co., Ltd., DIA FOIL T100) with a thickness of 38 μm by reciprocating a 2 kg rubber roller once. After leaving it in an environment of 23°C and 50% RH for 1 hour, using a small desktop tester (Shimadzu Corporation, EZ-L), the peeling of the PET film in the direction of 180° at a peeling speed of 300 mm/min was measured. Adhesion.

(Measurement of initial adhesion of surface protective film for transparent conductive film set)

A PET film (manufactured by KIMOTO, product name: KB film #) which has been subjected to hard coating treatment on one side of a biaxially stretched polyester film having a thickness of 50 μm and which has also been used for hard coating treatment of an ITO film is used. 50G01). The transparent conductive film cut to a width of 25 mm was bonded to the surface of the PET film subjected to the hard coating process with a surface protective film, and then stored in an environment of 23° C. and 50% RH for 1 hour to prepare an initial bond. Determination of force samples. Then, using a tensile tester, the strength when peeling the surface protective film for a transparent conductive film at a peeling speed of 300 mm/min in the direction of 180° was measured and used as the initial adhesion force (N/25 mm).

As the measuring device, a small desktop test device model EZ-L manufactured by Shimadzu Corporation was used.

<Measurement of adhesion after heating of surface protective film for transparent conductive film>

The transparent conductive film cut to a width of 25 mm was bonded to the surface of the PET film subjected to the hard coating treatment, and then stored at 150°C for 1 hour as a sample for measuring the adhesion after heating. Except for this, it was measured in the same manner as the measurement of the initial adhesive force, and this was regarded as the adhesive force after heating (N/25 mm).

As the measuring device, a small desktop test device model EZ-L manufactured by Shimadzu Corporation was used.

(Method for confirming handleability when bonding surface protective film for transparent conductive film on hard coating PET film)

As the surface protective film for a transparent conductive film described below, a sample subjected to an appearance inspection of the surface protective film for a transparent conductive film was used. A surface protective film for a transparent conductive film was stuck on the hard coating surface of the PET film (product name: KB film #50G01 manufactured by Kimoto Co., Ltd.) after hard coating treatment, and then the laminate was cut into A4 size. Hold one of the four corners of the cut sample and vibrate 20 times back and forth with the film surface fanning in the air. Then, visually confirm whether the hard-coated PET film is bent or deformed. The samples with no bending or deformation on the hard coating-treated PET film were evaluated as (○), and the samples with bending or deformation were evaluated as (×).

(Method of visual inspection of surface protective film for transparent conductive film)

Using a test coater, a roll product (400 mm width×100 m/roll) of a surface protective film for a transparent conductive film was produced, and the plate was kept in an oven at 40° C. for 5 days to cure the adhesive. Then, the appearance of the sample at a position 50 m away from the edge (position substantially equidistant from both ends) of the surface protective film for a transparent conductive film after rewinding from the roll product was visually observed. The sample with a smooth surface of the adhesive layer was evaluated as (○), the sample with weak irregularities on the surface of the adhesive layer was evaluated as (△), and the sample with strong irregularities on the surface of the adhesive layer was evaluated as ( ×).

(Method of visual inspection of hard coating treatment film)

As the surface protective film for a transparent conductive film described below, a sample subjected to an appearance inspection of the surface protective film for a transparent conductive film was used. A surface protective film for a transparent conductive film was laminated on the hard coating surface of the hard coating PET film (manufactured by KIMOTO, product name: KB film #50G01), and then subjected to heat treatment at 150°C for 1 hour. After peeling off the surface protective film for the transparent conductive film, the surface state of the hard coating-treated PET film was visually observed. A sample with a hard coating-treated PET film having a smooth appearance was evaluated as (◯), a sample with weak deformation of unevenness was evaluated as (△), and a sample with strong deformation of unevenness was evaluated as (×).

Table 1 shows the measurement results for each sample. In Table 1, "Polymer A" is an acrylic polymer described in Example 1, "Polymer B" is an acrylic polymer described in Comparative Example 2, and "Polymer C" is described in Comparative Example 3. The acrylic polymer, "crosslinking agent 1" is the HDI-based crosslinking agent described in Example 1 and Comparative Example 3, and "crosslinking agent 2" is the epoxy-based crosslinking agent described in Comparative Example 2. In addition, the value of the storage modulus in Table 1 is expressed by a form in which the mantissa and the exponent are described before and after E, and 4.0×10 ⁵ is, for example, 4.0E+05.

The following judgment is made from the measurement results shown in Table 1.

In Examples 1 to 2, the ratio of the adhesive force to the PET film of the adhesive layer used for the surface protective film for a transparent conductive film after 15 minutes from the start of drying of the adhesive layer and after aging at 40°C for 5 days "(A/b) is 1.4~1.6, the change of the adhesive force 15 minutes after the start of drying and the completion of aging (aging) is small, and the unevenness of the surface of the adhesive layer is very small. The hard-coated PET film using this surface protection film has a good appearance. In addition, the handleability when the surface protective films for transparent conductive films of Examples 1 to 2 were bonded to hard-coated PET films was also very good.

Regarding Example 3, "the ratio of the adhesive force to the PET film 15 minutes after the drying of the adhesive layer started and after aging at 40°C for 5 days" (a/b) was 2.0, compared with Examples 1 to 2, The irregularities on the surface of the adhesive layer slightly increased, but the irregularities on the surface of the adhesive layer were not transferred to the hard-coated PET film, and a hard-coated PET film with good appearance was obtained.

On the other hand, for Comparative Examples 1-2, "the drying of The ratio of the adhesive force to the PET film after 15 minutes at the beginning and after aging at 40°C for 5 days" (a/b) was 2.3 to 8.5, and the surface protective film for the transparent conductive film had irregularities on the surface of the adhesive layer. Therefore, when the laminated product bonded to the hard coating PET film is heat-treated, the uneven shape of the surface of the adhesive layer is transferred to the hard coating On the cloth-treated PET film, the appearance of the hard-coated PET film is reduced.

In addition, in Comparative Example 3, the storage modulus of the adhesive layer was as low as less than 4.0×10 ⁵ Pa, “the ratio of the adhesion of the adhesive layer to the PET film 15 minutes after the drying of the adhesive layer started and after aging at 40°C for 5 days. "(A/b) is 1.5. However, the surface protective film for a transparent conductive film of Comparative Example 3 had irregularities on the surface of the adhesive layer. Therefore, when the laminated product bonded to the hard-coated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard-coated PET film, and the hard-coated PET film Appearance drops.

For Comparative Example 4 where no crosslinking catalyst was added, in the evaluation of the adhesion of the PET film 15 minutes after the drying of the adhesive layer started, the adhesive layer was agglomerated and destroyed, and the surface protective film for the transparent conductive film was in the adhesive layer The surface has irregularities. Therefore, when the laminated product obtained by bonding the hard-coated PET film is heated, the uneven shape of the surface of the adhesive layer is transferred to the hard-coated PET film, and the appearance of the hard-coated PET film decline.

【Industrial Applicability】

The surface protective film for a transparent conductive film of the present invention has a very small curl even after a heating process in the state of being attached to a thinned transparent conductive film in the process of a transparent electrode for a touch panel . Thereby, the workability and production efficiency of the manufacturing process of the transparent electrode for touch panels can be greatly improved. In addition, the surface protective film for a transparent conductive film of the present invention can be used as a transparent conductive material in the technical fields such as touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic EL, solar cells, etc. Surface protective films for film manufacturing and processing are widely used.

1‧‧‧ Base film

2‧‧‧adhesive layer

3‧‧‧ peeling film

4‧‧‧ Adhesive film

5‧‧‧Surface protective film for transparent conductive film

Claims (2)

A surface protective film for a transparent conductive film used on the other surface of a transparent conductive film laminated to a resin film having a transparent conductive film formed on one surface, characterized in that the surface for the transparent conductive film The protective film is laminated with an adhesive layer on one side of the base film. The adhesive layer is coated with a polyisocyanate compound containing (meth)acrylic polymer, as a crosslinking agent, and an organic compound as a crosslinking catalyst. After the acrylic adhesive of the metal compound, it is formed by drying at a temperature of 130° C. for 1 minute. The acrylic adhesive contains 4 to 10 parts by weight of the crosslinking agent relative to 100 parts by weight of the (meth)acrylic polymer. 0.01 to 0.5 parts by weight of the cross-linking catalyst, the storage modulus of the adhesive layer at 30° C. is 4.0×10 ⁵ Pa or more, and 15 minutes after the drying of the adhesive layer starts, the adhesive layer is applied to the PET film The adhesive force of the adhesive layer and the adhesive force of the adhesive layer to the PET film after aging for 5 days at 40 ℃ satisfy the relationship of the following formula (1): 0.9

a/b

2.0 Formula (1) where a is the adhesion of the adhesive layer to the PET film 15 minutes after the drying of the adhesive layer starts, and b is the adhesion of the adhesive layer to the PET film after aging at 40°C for 5 days force. A transparent conductive film, which is a transparent transparent film obtained by bonding the surface protective film for a transparent conductive film as described in item 1 of the patent application range to the other surface of a resin film having a transparent conductive film formed on one surface Conductive film.

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