TWI627255B - Surface-protective film for transparent conductive film, and transparent conductive film using the same - Google Patents

Abstract

The invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. The adhesive layer of the surface protective film for a transparent conductive film maintains the smoothness of the surface, even if it is bonded to the transparent conductive film. It also has excellent handleability. In the manufacturing and processing processes of the transparent conductive film, the appearance defect caused by the surface protective film is improved, and the productivity is good in the manufacturing process of the transparent electrode for touch panels. A surface protective film 5 for a transparent conductive film is used by being bonded to the other surface of a transparent conductive film having a transparent conductive film formed on one surface of a resin film, and laminated on one side of the base film 1 The adhesive layer 2 is made of an adhesive containing an acrylic resin composition, a cross-linking agent, and a cross-linking catalyst. The adhesive layer after aging at 40 ° C for 5 days at 30 ° C has a storage modulus a of 4.0 × 10 ⁵ Above Pa, the storage modulus b and a at 30 ° C of the adhesive layer 15 minutes after the start of drying satisfy the relationship of 0.9 a / b 1.3.

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 by being bonded to the other surface of a transparent conductive film having a transparent conductive film formed on one surface of a resin film, 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, an adhesive layer formed maintains surface smoothness. It has excellent handleability even when bonded to a transparent conductive film. In the manufacturing and processing processes of transparent conductive films, defects caused by the appearance defects of the surface protective film are improved, and transparent electrodes for touch panels are manufactured. Good productivity in the manufacturing process.

In the technical fields such as touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic ELs, and solar cells, transparent conductive films (hereinafter, sometimes referred to simply as "conductive films" ") Is widely used for forming applications such as transparent electrodes. This transparent conductive film has a transparent conductive film made 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 manufacturing process of the transparent electrode for a touch panel, various heating processes and reagent processing processes are required. For example, a 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 glue, printing process of insulating layer, punching process, etc. In the manufacturing process of such a transparent electrode, a surface protective film for a transparent conductive film is bonded and used in order to prevent contamination or damage on the opposite side of the surface of the transparent conductive film on which the transparent conductive film is formed.

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

Various proposals have been made regarding a protective film for a transparent conductive film used in a manufacturing process of a transparent electrode such as a touch panel. For example, Patent Document 1 proposes a surface protective film for a transparent conductive film, in which an adhesive layer is provided on one surface of a substrate made of a thermoplastic resin film having a melting point of 200 ° C. or higher. Compared with a surface protective film for a transparent conductive film using a polyolefin resin such as polyethylene and polypropylene as a base material, it has good heat resistance.

In addition, Patent Document 2 proposes a method for producing a surface protective film for a transparent conductive film, in which a substrate film containing a polyethylene terephthalate resin and / or a polyethylene naphthalate resin is used. After the adhesive is applied on one side, it is dried at a predetermined temperature, residence time, and tensile tension. It is thought that 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, a large curl does not occur.

Patent Document 3 proposes a resin film with a transparent conductive film and a protective film, wherein a transparent conductive film is provided on one side of the resin film, and a protection is provided on a resin film surface opposite to the surface on which the transparent conductive film is provided. Film, the protective film is composed of a first film and a second film, and the first film and the second film are sequentially arranged from the resin film, and the thermal shrinkage of the first film after heating at 150 ° C for 30 minutes is between MD and TD Both directions are 0.5% or less, and the second film has a linear expansion coefficient whose difference from the linear expansion coefficient of the above-mentioned resin film with a transparent conductive film and a protective film is 40 ppm / ° C or less. If this invention is applied, the transparent conductive film which does not have the dimensional change and curl caused by the heat processing in processing processes, such as a touch panel formation, can be obtained.

In addition, Patent Document 4 proposes a surface protective film for a transparent conductive film. By using a release film having a predetermined thickness and a bending resistance, the surface of the adhesive layer of the surface protective film is smoothed, and appearance defects are improved.

[Existing technical 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 Application Publication 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 in the same manner as in Patent Document 4. The surface protection film of Patent Document 4 is characterized by use A peeling film having a bending resistance at 40 ° C. of 0.30 mN to 40 mN, but a film having this bending resistance has a problem that the thickness is increased and the cost is increased. In addition, when manufacturing a surface protection film or when a user uses a 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, compared with a surface protection film using a release film with a thin substrate, a surface protection film using a release film with a thick substrate has the following problems: The roll-up length at the time of shortening is shortened, and productivity in a manufacturing process of a transparent electrode for a touch panel is reduced.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. Next, the adhesive layer of the surface protective film for transparent conductive films maintains the smoothness of the surface, and has excellent handleability even when bonded to the transparent conductive film. It is caused by the manufacturing and processing processes of transparent conductive films. The appearance defect of the surface protective film for a transparent conductive film is improved, and the productivity in a manufacturing process of a transparent electrode for a touch panel is good.

A surface protective film for a transparent conductive film is produced by applying an adhesive to a base film or a release film, and evaporating a solvent in the adhesive during a drying process, and then attaching the release film or the base film to the surface protective film. Roll into a roll shape. The inventors conducted intensive studies and found that the curing state of the adhesive layer 15 minutes after the start of drying is related to the uneven shape of the surface of the adhesive layer. Furthermore, it was found that by using an adhesive layer in which an adhesive layer is cured within 15 minutes after the start of drying, even when a thin release film is used for the surface of a transparent conductive film In the case of the application of the adhesive layer of the protective film, it is possible to suppress the deformation of the unevenness on the surface of the adhesive layer to be adhered to the adherend, and the present invention was completed.

In the manufacturing process of the surface protective film, the base film is usually coated with an adhesive and dried to form an adhesive layer, and then is cured in a roll state. However, during this curing period, the Deformation of the release film occurs due to the effects of winding and the like. Therefore, in the case where the adhesive layer is cured after the release film is deformed, the surface shape of the release film is transferred to the surface of the adhesive layer. When the transparent conductive film is manufactured and processed, this will become a significant appearance of the transparent conductive film. Cause of deterioration.

The technical idea of the present invention is as follows: during curing of the surface protective film for a transparent conductive film in a roll shape, curing of the adhesive layer is performed before the release film is deformed, so that even if the release film is deformed, it can be suppressed The surface of the adhesive layer is deformed, thereby maintaining smoothness.

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

The inventors have found that by comparing the storage modulus of the adhesive layer 15 minutes after the drying of the adhesive layer and the completion of the aging (aging), the progress of curing of the adhesive layer can be grasped. More specifically, if the ratio of the storage modulus after the drying of the adhesive layer 15 minutes after the aging (aging) is completed (the storage modulus after the aging is completed divided by the storage modulus 15 minutes after the drying Value) within a predetermined range, even when the release film with a thin substrate thickness In the case of bonding the adhesive layer of the surface protective film for a transparent conductive film, it is possible to suppress uneven deformation of the surface of the adhesive layer to be adhered 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 adhered to the other surface of a transparent conductive film in which a transparent conductive film is formed on one surface of a resin film, and is characterized in that it is a surface protective film for a transparent conductive film It is formed by laminating an adhesive layer on one side of a base film. The adhesive layer is formed using an adhesive containing an acrylic resin composition, a crosslinking agent, and a crosslinking catalyst, and is aged at 40 ° C. The storage modulus of the adhesive layer at 30 ° C after 5 days is 4.0 × 10 ⁵ Pa or more, and the storage mold of the adhesive layer at 30 ° C after the adhesive layer starts to dry for 15 minutes The relationship between the number and the storage modulus of the adhesive layer at 30 ° C after aging at 40 ° C for 5 days satisfies the following formula (1).

(Here, a is the storage modulus of the adhesive layer at 30 ° C after aging at 40 ° C for 5 days, and b is the adhesive layer at 30 ° C after the adhesive layer starts to dry for 15 minutes. (Storage modulus at ℃)

The present invention also provides a transparent conductive film obtained by bonding the surface protective film for a transparent conductive film described above to the other surface of a transparent conductive film having a transparent conductive film formed on one surface of a resin film. Transparent conductive film.

The present invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. The table for a transparent conductive film of the present invention The surface protective film is wound from the drum, and the formed adhesive layer maintains the smoothness of the surface. Even if it is bonded to the transparent conductive film, it has excellent handling properties. It is used in the manufacturing and processing processes of transparent conductive films. The defect due to the appearance defect of the surface protection film is improved, and the productivity in the manufacturing process of the transparent electrode for a touch panel is good.

In addition, in recent years, as the thickness of a housing of a high-function portable terminal such as a smartphone is reduced, the thickness of a transparent conductive film used has been continuously reduced. In the manufacturing process of the transparent electrode for a touch panel, the surface protective film for a transparent conductive film of the present invention has a very small curl even after being subjected to a heating process in a state of being bonded to a thin transparent conductive film. . This can significantly improve workability and production efficiency in the manufacturing process of the transparent electrode for a touch panel.

1‧‧‧ substrate 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‧‧‧ roller for peeling film

22‧‧‧ Roller for substrate film

23‧‧‧Adhesive coating device

24‧‧‧ Drying Furnace

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 a surface protective film for a transparent conductive film of the present invention.

FIG. 2 is a cross-sectional view showing an example in which the surface protective film for a transparent conductive film of the present invention is bonded to a transparent conductive film.

FIG. 3 is a schematic diagram showing an example of a method for producing 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 a surface protective film for a transparent conductive film of the present invention. The surface protective film 5 for a transparent conductive film has an adhesive layer 2 laminated on one surface of a transparent flexible substrate film 1. Laminated adhesive layer 2 The surface is adhered to the surface of the adherend, and the treated release film 3 is laminated to protect the surface of the adhesive layer through the peeled surface.

As the base film 1, a transparent flexible plastic film is used. Accordingly, the surface conductive film for a transparent conductive film of the present invention can be directly adhered and bonded to the other surface of the transparent conductive film having the transparent conductive film formed on one surface of the substrate. Visual inspection of the film. Examples of the plastic film used as the base film 1 include polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polyisophthalate. Polyester film such as polybutylene terephthalate. In addition, in addition to the polyester film, as long as it is a plastic film having the required strength and optical compatibility, other resin types of plastic films may be used. The base film 1 is an unstretched film, a uniaxially or biaxially stretched film, and the like, and is not particularly limited, but the heat shrinkage of the base film is preferably low.

The thickness of the base film 1 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited, and it may be selected according to the transparent conductive film to be used. When 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 protection film having a thickness of about 25 to 75 μm of the base film 1 of the surface protection film can be used.

On the other hand, when the transparent conductive film used is as thin as 50 μm or less, the handleability of the transparent conductive film itself is poor. Therefore, the handleability of the surface protective film must also be considered. A transparent conductive film is preferred. The specific thickness of the substrate film is preferably about 100 to 188 μm.

In addition, if necessary, an antifouling layer, an antistatic layer, an oligomer preventing layer, or an anti-damage layer for preventing surface dirt can be laminated on the opposite side of the surface on which the adhesive layer 2 is laminated on the base film 1. Hard-coating, corona discharge treatment, anchor coating treatment, etc.

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-liquid type 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) is preferably one in which a crosslinking agent is added and a tackifier is added if necessary. (Meth) acrylic polymers are usually main monomers such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, and acrylonitrile, vinyl acetate, and methyl methacrylate. And other comonomers such as acrylic acid, ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylolmethacrylamide, etc. Polymer. The monomer composition of the (meth) acrylic polymer is preferably 50% or more, and the (meth) acrylic monomer may be 100%.

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

The polyisocyanate compound is classified into an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an alicyclic isocyanate, and the like, and 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 dimethylene diisocyanate (H6XDI), o- tolidine Diisocyanate (TOID), toluene diisocyanate (TDI) and other aromatic isocyanate compounds.

Examples of the trifunctional or higher isocyanate compounds include biuret-type modifiers and trimer isocyanate-type modifiers of diisocyanates (compounds having two NCO groups in one molecule); and trimethylolpropane (TMP ), Adducts (polyol modifiers) of trivalent or higher polyols (compounds having at least 3 or more OH groups in one molecule) such as glycerol, and the like.

The addition amount of the cross-linking agent may be determined in consideration of the type, degree of polymerization, and amount of functional groups of the (meth) acrylic polymer. Although it is not particularly limited, it is usually relative to 100 parts by weight of the (meth) acrylic polymer. The crosslinking agent is set to about 0.5 to 10 parts by weight.

In addition, the surface protective film for a transparent conductive film according to the present invention needs to cure the adhesive layer before the peeling film is deformed during curing in a roll shape. Therefore, in order to promote the (meth) acrylic polymer, For a crosslinking reaction with a crosslinking agent, a crosslinking catalyst is preferably added. 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. In the case of using a polyisocyanate compound as the cross-linking agent, Organic compounds such as amine compounds such as tertiary amines, organic tin compounds, organic lead compounds, organic zinc compounds, and organic iron compounds are produced.

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

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

The addition amount of the cross-linking catalyst may be determined in consideration of the type of the (meth) acrylic polymer, the degree of polymerization, the amount of functional groups, the type of the cross-linking catalyst, and the amount of the cross-linking catalyst. Although not particularly limited, it is relative to acrylic 100 parts by weight of the polymer is usually about 0.01 to 0.5 parts by weight.

In addition, in order to suppress excessive viscosity increase, gelation, and prolong the pot life of the adhesive composition after the preparation of the crosslinking agent, a crosslinking delaying agent may be contained as necessary.

Examples of the crosslinking delaying agent include β-keto acids such as methyl ethyl acetate, ethyl ethyl acetate, octyl ethyl acetate, oleyl ethyl acetate, lauryl ethyl acetate, and stearyl ethyl acetate. Β-diketones such as esters, acetoacetone, 2,4-hexanedione, and benzophenone acetone. Particularly, at least one or more members selected from the group consisting of acetoacetone and acetoacetate are preferred. These crosslinking delaying agents are keto-enol tautomeric compounds. In a binder composition using a polyisocyanate compound as a crosslinking agent, by blocking the isocyanate group of the crosslinking agent, the cross-linking agent can be inhibited from being formulated. Excessive viscosity increase and gelation of the adhesive composition can extend the pot life of the adhesive composition.

Although the addition amount of a crosslinking delaying agent is not specifically limited, About 1.0-5.0 weight part is usually added with respect to 100 weight part of (meth) acrylic-type polymers.

In addition, a tackifier may be added to the adhesive as needed. Make Examples of the tackifier include rosin, benzofuranindene, terpene, petroleum, and phenol.

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

The thickness of the adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited, but 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 a surface protective film for a transparent conductive film increases, and thus competitiveness is impaired. When the thickness of the adhesive layer 2 is less than 5 μm, there are problems in that the adhesiveness to the transparent conductive film is reduced, or when a foreign matter is mixed when the surface protective film is bonded to the transparent conductive film, the conductive is transparent The sexual film 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 an adherend of about 0.05 to 0.5 N / 25 mm. A micro-adhesive layer with a slight adhesiveness is preferred. By forming a surface protective film for a transparent conductive film having such a micro-adhesive layer, it is possible to obtain an excellent operability that can be easily peeled from an adherend.

The material of the release film 3 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited. Examples of the material of the release film that can be used include polyolefin films such as polyethylene films, polypropylene films, and polymethylpentene films, and the use of polysiloxane-based release agents on the surface of films such as polyester films. A release film, a fluororesin film, a polyimide film, or the like subjected to a release treatment. In addition, a film in which a plurality of films are laminated using a bonding agent, or a laminated film in which a resin is melt-extruded on the film and laminated may be used. These single-layer films or laminated films are subjected to a release treatment using a release agent such as a polysiloxane-based release agent to obtain a release film.

The thickness of the release film 3 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited, and a release film having a thickness that is easy to use may be selected. Usually, it is a release film of about 19 to 75 μm.

When the release film 3 is thick, the length of the surface protective film for a transparent conductive film is shortened in a roll having the same roll diameter as a roll, and the manufacturing cost is increased. Therefore, the release film 3 is guided to an appropriate thickness. The release film 3 is preferably a release film obtained by performing a release treatment on a single-layer polyester film, and a release film obtained by performing a release treatment on a film in which a polyester film is laminated in multiple layers using an adhesive.

The method of sequentially laminating the adhesive layer 2 and the release film 3 on the base film 1 may be performed by a known method, and is not particularly limited. Specifically, the method may be a method of applying the adhesive layer 2 on the base film 1 and drying and attaching the release film 3, and applying the adhesive layer 2 on the release film 3 and drying and attaching the base film 1 Any one of the methods.

The formation of the adhesive layer on the base film 1 can be performed by a known method. Specifically, known coating methods such as a reverse coating method, a comma coat method, a gravure printing method, a slot die coating method, a Mel bar coating method, and an air knife coating method can be used.

A method of applying a peeling treatment to the release film 3 may be performed by a known method. Specifically, a release agent is applied to one surface of the release film 3 by a coating method such as a gravure printing method, a Mayer bar coat method, an air knife coating method, and the like, and heat or ultraviolet irradiation is applied to the release film. The release agent may be dried and cured. If necessary, the film to be subjected to the peeling treatment may be previously subjected to pretreatment such as corona treatment, plasma treatment, anchor coating or the like to improve the adhesiveness of the release agent to the film.

In addition, FIG. 2 is a schematic configuration diagram showing an example of a laminated film 11 obtained by bonding the surface protective film for a transparent conductive film of the present invention to a transparent conductive film.

This laminated film 11 is a laminated film obtained by bonding an adhesive film 4 to the surface of a transparent conductive film 10 with its adhesive layer 2. The adhesive film 4 is a surface protective film for a transparent conductive film of the present invention. 5 is obtained by peeling the release film 3 from above. The transparent conductive film 10 has a transparent conductive film 7 formed on one surface 6 a of the resin film 6. The adhesive film 4 is bonded to the other surface 6 b 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. Like polyolefin film. Such transparent conductive films are widely used in transparent electric fields in the technical fields such as touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic ELs, and solar cells. Extreme formation use.

The surface protective film for a transparent conductive film of the present invention exhibits the following excellent effects: In the manufacturing process of a transparent electrode such as a touch panel, workability and production efficiency can be greatly improved, and even a thin transparent conductive film can be used. Does not reduce workability and handling.

Moreover, FIG. 3 is a schematic diagram which shows an example of the manufacturing method of the surface protection film for transparent conductive films of this invention.

The release film 3 and the base film 1 are continuously discharged from the drum 21 where the release film 3 subjected to the peeling treatment is wound, and the drum 22 where the base film 1 is wound, respectively. An adhesive is applied to one surface of the base film 1 by an adhesive application device 23. The adhesive-coated substrate film 1 is dried in a drying furnace 24 to form an adhesive film 4. The surface of the pressure-sensitive 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 pressure bonding was performed using pressure rollers 25 and 26 to obtain a surface protective film 5 for a transparent conductive film. The surface protective film 5 for a transparent conductive film is rolled up into a drum 27. Normally, the surface protective film 5 for a transparent conductive film is stored and transported in a state of a drum 27. When bonded to the transparent conductive film 10, the surface protective film 5 for a transparent conductive film is wound back from the drum 27.

[Example]

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

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

On one side of the biaxially stretched polyester film having a thickness of 25 μm, a coating was applied by the Mel bar method so that the thickness of the dried polysiloxane film was 0.1 μm. The coating is an addition reaction Polysiloxane (manufactured by Toray Dow Corning, product name: SRX-211 100 parts by weight with platinum catalyst SRX-212 1 part by weight) Toluene / A coating obtained by diluting a 1: 1 mixed solvent of ethyl acetate. Furthermore, it dried and solidified in the hot-air circulation type oven of 120 degreeC for 1 minute, and obtained the peeling film of Example 1.

In addition, the adhesive layer is formed using an adhesive composition, which is an acrylic polymer 100 having a solid content of 40% by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate. An adhesive composition obtained by adding and mixing 4 parts by weight of HDI-based crosslinking agent (manufactured by Japan Polyurethane Industry Co., Ltd., product name: CORONATE HX) and 0.03 parts by weight of dibutyltin dilaurate as a crosslinking catalyst. The adhesive composition was coated on a polyethylene terephthalate film having a thickness of 125 μm so that the thickness of the dried adhesive layer was 20 μm. The adhesive was dried in a hot air circulation oven at a temperature of 130 ° C. 1 minute. Then, the silicone- treated surface of the release film of Example 1 produced as described above was laminated on the surface of the adhesive layer to obtain a surface protective film for the transparent conductive film of Example 1.

(Production of a surface protective film for a 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 based on 100 parts by weight of the acrylic polymer.

(Production of a surface protective film for a transparent conductive film in 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 drying temperature of the adhesive layer was 120 ° C.

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

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

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

A surface protective film for a transparent conductive film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the drying temperature of the adhesive layer was 100 ° C.

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

In addition to using 100% by weight of an acrylic polymer having a solid content of 40% by copolymerizing 2-ethylhexyl acrylate, butyl acrylate, and 2-hydroxyethyl acrylate, a polyurethane-based crosslinking agent (Japanese polyurethane (Product name: CORONATE HX) manufactured by Kogyo Co., Ltd. 1 part by weight and 0.03 parts by weight of dibutyltin dilaurate as a cross-linking catalyst were mixed and the adhesive composition was the same as Example 1 except that the adhesive composition was the same Method to obtain a surface protective film for a transparent conductive film of Comparative Example 3.

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

In addition to the addition of an epoxy-based crosslinking agent (made by Mitsubishi Gas Chemical Co., Ltd., 100% by weight of an acrylic polymer having a solid content of 40% by copolymerizing butyl acrylate, 2-ethylhexyl acrylate and acrylic acid) : TETRAD-C) In the same manner as in Example 1 except that the adhesive composition obtained by mixing 4 parts by weight of the adhesive composition was a surface protective film for a transparent conductive film of Comparative Example 4.

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

(Measurement of storage modulus)

For the samples obtained in the examples and comparative examples, a viscoelasticity measuring device was used. (Reogel-E4000, a dynamic viscoelasticity measuring device manufactured by ABM Co., Ltd.) The storage modulus (b) of the adhesive layer at 30 ° C 15 minutes after the drying of the adhesive layer was started, and the storage modulus at 40 ° C for 5 days The storage modulus (a) of the adhesive layer at 30 ° C.

In the following Table 1, the storage modulus (b) is abbreviated as "storage modulus (b) before curing", and the storage modulus (a) is abbreviated as "storage modulus (a) after curing", The ratio (a / b) of the two is abbreviated as "the ratio after curing / before curing (a / b)".

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

A PET film (KIMOTO company, product name: KB film) that has been hard-coated on one side of a biaxially stretched polyester film with a thickness of 50 μm and also hard-coated for ITO film is used. # 50G01). A transparent protective film cut to a width of 25 mm was bonded to the surface of the hard-coated surface of the PET film with a surface protective film, and then stored in an environment of 23 ° C and 50% RH for 1 hour to make an initial adhesion. Force measurement sample. Then, using a tensile tester, the strength when the surface protective film for a transparent conductive film was peeled in a direction of 180 ° at a peeling speed of 300 mm / minute was measured, and this was used as the initial adhesive force (N / 25 mm).

As the measurement device, a small-sized desktop test device of the type EZ-L manufactured by Shimadzu Corporation was used.

<Measurement of Adhesion After Heating of Surface Protective Film for Transparent Conductive Film>

A transparent protective film cut to a width of 25 mm was bonded to a hard-coated surface of a PET film with a surface protective film, and then stored at 150 ° C for 1 hour as a sample for measuring adhesion after heating. In addition, with the initial adhesion The measurement of the force was performed similarly, and this was made into the adhesive force after heating (N / 25mm).

As the measurement device, a small-sized desktop test device of the type EZ-L manufactured by Shimadzu Corporation was used.

(Method for confirming handling properties when a surface protective film for a transparent conductive film is bonded to a hard-coated PET film)

As a surface protective film for a transparent conductive film described below, a sample having a visual inspection of the surface protective film for a transparent conductive film was used. A surface protective film for a transparent conductive film was bonded to a hard-coated surface of a hard-coated PET film (manufactured by KIMOTO Co., Ltd .: KB film # 50G01), and the laminated product was cut to A4 size. Hold one of the four corners of the cut sample, and vibrate back and forth 20 times with the film surface fanning in the air. Then, it was visually confirmed that the hard-coated PET film was bent or deformed. A sample without bending or deformation on the hard-coated PET film was evaluated as (○), and a sample having bending or deformation was evaluated as (×).

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

A rolled product (400 mm width × 100 m / roll) of a surface protective film for a transparent conductive film was produced using a test coater, and was held in an oven at 40 ° C. for 5 days to cure the adhesive. Then, the external appearance of a sample of a portion (positions approximately equidistant from both ends) of the transparent protective film surface protective film 50 m from the roll (a position approximately equidistant from both ends) after being wound from the roll was visually observed. A sample with a smooth surface of the adhesive layer was evaluated as (○), a sample having weak unevenness on the surface of the adhesive layer was evaluated as (△), and a sample having strong unevenness on the surface of the adhesive layer was evaluated as ( ×).

(Method for visual inspection of hard-coated film)

As a surface protective film for a transparent conductive film described below, a sample having a visual inspection of the surface protective film for a transparent conductive film was used. PET for hard coating A film (manufactured by KIMOTO Corporation, product name: KB film # 50G01) was bonded with a surface protective film for a transparent conductive film on the hard-coated surface, and then heat-treated at 150 ° C. for 1 hour. After peeling the surface protective film for a transparent conductive film, the surface state of the hard-coated PET film was visually observed. A sample with a smooth outer appearance of the hard-coated PET film was evaluated as (○), a sample having weak unevenness was evaluated as (Δ), and a sample having strong unevenness was evaluated as (×).

The measurement results for each sample are shown in Table 1. In Table 1, "Polymer A" is the acrylic polymer described in Example 1, "Polymer B" is the acrylic polymer described in Comparative Example 3, and "Polymer C" is the polymer described in Comparative Example 4. In the acrylic polymer, "crosslinking agent 1" is the HDI-based crosslinking agent described in Example 1, and "crosslinking agent 2" is the epoxy-based crosslinking agent described in Comparative Example 4. In addition, the value of the storage modulus in Table 1 is represented by a format in which a mantissa and an index are described before and after E, and 4.0 × 10 ⁵ is described as 4.0E + 05, for example.

From the measurement results shown in Table 1, the following judgments were made.

In Examples 1 and 2, the storage layer of the adhesive layer used in the surface protective film for a transparent conductive film, "The adhesive layer 15 minutes after the drying of the adhesive layer started at 30 ° C and the storage modulus at 40 ° C The ratio of the storage modulus of the adhesive layer at 30 ° C after 5 days aging ("a / b") is 1.0 to 1.2, the change of the adhesive force before and after the heating process is small, and the unevenness on the surface of the adhesive layer is very small ( small). The appearance of the hard-coated PET film using this surface protective film was good. In addition, when the surface protective film for the transparent conductive film of Examples 1 to 2 was bonded to a hard-coated PET film, the handleability was also very good.

Regarding Example 3, as compared with Examples 1 and 2, the unevenness on the surface of the adhesive layer was slightly increased, but the unevenness on the surface of the adhesive layer was not transferred to the hard-coated PET film, and a good appearance was obtained. Hard-coated PET film.

On the other hand, in Comparative Example 1 to which no cross-linking catalyst was added, the adhesive used in the surface protective film for a transparent conductive film was "the adhesive layer 15 minutes after the drying of the adhesive layer started at 30 ° C. The ratio of the storage modulus at that time to the storage modulus of the adhesive layer at 30 ° C after aging at 40 ° C for 5 days "(a / b) is 27.5. The surface protective film for a transparent conductive film on the adhesive layer The surface is uneven. Therefore, when the laminated product laminated with 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. Appearance drops.

In Comparative Example 2, "The ratio of the storage modulus of the adhesive layer at 30 ° C 15 minutes after the drying of the adhesive layer started at 30 ° C to the storage modulus of the adhesive layer at 30 ° C after aging at 40 ° C for 5 days "(A / b) is 1.5, and a surface protective film for a transparent conductive film has unevenness on the surface of the adhesive layer. Therefore, in the processing of PET with hard coating When the laminated product obtained by film bonding 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 appearance of the hard-coated PET film is deteriorated.

In addition, in Comparative Example 3 using an adhesive layer having a low storage modulus, "The storage modulus of the adhesive layer 15 minutes after the drying of the adhesive layer started at 30 ° C and after aging at 40 ° C for 5 days The ratio "(a / b) of the storage modulus of the adhesive layer at 30 ° C was 1.1, but the surface protective film for a transparent conductive film of Comparative Example 3 had unevenness on the surface of the adhesive layer. Therefore, when the laminated product laminated with 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. Appearance drops.

In Comparative Example 4, the adhesive used in the surface protective film for a transparent conductive film, "the storage layer of the adhesive layer 15 minutes after the drying of the adhesive layer started at 30 ° C and aged at 40 ° C for 5 days The ratio “(a / b) of the storage modulus of the subsequent adhesive layer at 30 ° C.” was 10.0, and a surface protective film for a transparent conductive film had unevenness on the surface of the adhesive layer. Therefore, when the laminated product laminated with 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. Appearance drops.

[Industrial Applicability]

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

Claims (2)

A surface protective film for a transparent conductive film, which is used for bonding to the other surface of a transparent conductive film in which a transparent conductive film is formed on one surface of a resin film. The surface of the transparent conductive film is characterized in that: The protective film is formed by laminating an adhesive layer on one side of the base film. The adhesive layer is formed using an adhesive containing an acrylic resin composition, an isocyanate crosslinking agent, and a crosslinking catalyst, and is aged at 40 ° C. After 5 days, the storage modulus of the adhesive layer at 30 ° C. is 4.0 × 10 ⁵ Pa or more, and the storage modulus of the adhesive layer at 30 ° C. after the adhesive layer starts to dry for 15 minutes is less than that at 30 ° C. The storage modulus of the adhesive layer after aging at 40 ° C for 5 days at 30 ° C satisfies the relationship of the following formula (1): Wherein, a is the storage modulus of the adhesive layer at 30 ° C after aging at 40 ° C for 5 days, and b is the storage modulus of the adhesive layer at 30 ° C after the adhesive layer starts to dry for 15 minutes. . A transparent conductive film comprising a surface protective film for a transparent conductive film described in item 1 of the scope of patent application, which is bonded to the other surface of a transparent conductive film having a transparent conductive film formed on one surface of a resin film. The obtained transparent conductive film.