TWI666293B - 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, defects due to the appearance of the surface protective film are improved, and the productivity in the manufacturing process of the transparent electrode for a touch panel is good. A surface protective film 5 for a transparent conductive film, which is used for bonding to the other surface of a resin film having a transparent conductive film formed on one surface, and having isocyanate-containing compounds on one surface of the base film 1 Adhesive layer 2 laminated with a cross-linking agent and an acrylic adhesive of a cross-linking catalyst. The storage modulus of the adhesive layer at 30 ° C. is 4.0 × 10 ⁵ Pa or more, and drying of the adhesive layer begins 15 The reaction rate K of the adhesive layer after 75 minutes was 75% or more.

Description

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

The present invention includes a surface protective film for a transparent conductive film used for bonding to 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 surface smoothness. It has excellent handleability even if it is bonded to a transparent conductive film. In the manufacturing and processing processes of transparent conductive films, defects caused by the appearance of the surface protective film are improved, and in the process of manufacturing transparent electrodes for touch panels Good productivity.

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 process of manufacturing transparent electrodes for touch panels, a variety of heating processes and reagent processing processes are required. For example, a transparent conductive film having 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, 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 substrate, it has better 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. 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 the 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, a transparent conductive film that does not have dimensional changes and curl caused by heat treatment in processing processes such as 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 defects in appearance are improved. .

[Existing technical literature] [Patent Literature]

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

Patent Document 2: Japanese Patent No. 4342775

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

Patent Document 4: Japanese Patent Application Publication No. 2013-226676

The present invention provides a transparent guide in which the adhesive layer of a surface protective film maintains the smoothness of the surface and the defect of the appearance is improved in the same manner as in Patent Document 4. Surface protective film for electrical film. The surface protection film of Patent Document 4 is characterized in that a peeling film having a bending resistance of 0.30 mN to 40 mN at 40 ° C is used. However, the 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, the surface protection film using a release film having a thick substrate has a problem that, compared with a surface protection film using a release film having a thin substrate, it is rolled up with a predetermined winding diameter. At this time, the roll-up length becomes shorter, and productivity in a manufacturing process of a transparent electrode for a touch panel decreases.

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. 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 transparent conductive films. It is caused by transparent conductive during the manufacturing and processing of transparent conductive films. The defect of the external appearance of the surface protective film for sexual films is improved, and the productivity in a transparent electrode manufacturing process for a touch panel is good.

A surface protective film for a transparent conductive film is produced by coating an adhesive on 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 a roll. Into a roller 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. It was further found that by using an adhesive layer, a cured adhesion occurred within 15 minutes after the start of drying. Agent, even when a release film having a thin base material is used for bonding an adhesive layer of a surface protective film for a transparent conductive film, it is possible to suppress the above-mentioned adhesive layer from being adhered to the adhesive layer. The surface of the object is deformed by unevenness, thereby completing the present invention.

In the process of manufacturing a surface protection film, an adhesive is usually applied to a substrate film and dried to form an adhesive layer, and then the film is cured in a roll state. However, during this curing period, the Deformation of the release film occurs due to the short-term influence. Therefore, when 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, the transparent conductive film will have a significant appearance. 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, the adhesive layer is applied before the adhesive layer to which the release film is bonded is deformed and pulled by the deformation of the release film. Curing to prevent unevenness on the surface of the adhesive layer bonded to the adherend, thereby maintaining smoothness.

The inventors have found that by measuring the reaction rate of the adhesive layer 15 minutes after the drying of the adhesive layer and the storage modulus of the adhesive layer after aging (aging) are completed, the progress of curing of the adhesive layer can be grasped. More specifically, if the reaction rate of the adhesive layer 15 minutes after the drying of the adhesive layer starts and the storage modulus of the adhesive layer after the aging (aging) is completed are within a predetermined range, When the release film with a thin substrate is used for bonding the adhesive layer of the surface protective film for a transparent conductive film, it is possible to suppress the occurrence of the surface of the adhesive layer to be adhered to the adherend. Deformation of bumps.

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 used for bonding to the other surface of a resin film having a transparent conductive film formed on one surface, wherein the surface protective film for a transparent conductive film has a substrate An adhesive layer obtained by laminating an acrylic adhesive containing an isocyanate crosslinking agent and a crosslinking catalyst on one side of the material film. The storage modulus of the adhesive layer at 30 ° C is 4.0 × 10 ⁵ Pa Above, and the reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of the adhesive layer represented by the following formula is 15 minutes or more.

Reaction rate K (%) = (1-a / b) × 100

When (here, a is the peak intensity ratio of the drying start 1730cm through Fourier transform infrared light absorption of the adhesive layer 15 minutes after spectrophotometric determination 2270cm ^-1 / ^-1 of the adhesive layer, b uncured the adhesive layer transform infrared absorption peak intensity of 2270cm ^-1 / 1730cm ^-1 spectrophotometry ratio obtained through the Fourier)

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

The invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. The surface for a transparent conductive film of the invention In the state where the protective film is wound from the drum, the formed adhesive layer maintains the smoothness of the surface, and has excellent handleability even when bonded to a transparent conductive film. In the manufacturing process of the transparent conductive film, The defect caused by the appearance of the surface protection film is improved, and the productivity is good in the manufacturing process of the transparent electrode for a touch panel.

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. Adhesive layer 2 to be attached On the surface of the adherend, a release-treated peeling film 3 is laminated to protect the surface of the adhesive layer via 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. As the plastic film used as the base film 1, preferred examples include polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polyethylene terephthalate. 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. Although not particularly limited, it is preferred that the base film has a low heat shrinkage rate.

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 prevention 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 A hard-coating layer, or an adhesion-prone treatment such as a corona discharge treatment or an anchor coat 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, and among them, an acrylic adhesive using an isocyanate-based crosslinking agent and a crosslinking catalyst is preferred. Transparent conductive film A surface protective film is used in a state where the transparent conductive film is protected, and there is no particular limitation on the composition of the acrylic adhesive, and there is no particular limitation on the composition of the acrylic adhesive. material.

As the acrylic adhesive, a (meth) acrylic polymer (acrylic resin composition) is preferably an adhesive in which a crosslinking agent is added and a tackifier is required to be added. (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. Comonomers such as acrylic acid, ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylolmethacrylamide, etc. Polymer. The (meth) acrylic monomer having a preferable monomer composition constituting the (meth) acrylic polymer is 50% or more, and the (meth) acrylic monomer may be 100%.

As the crosslinking agent, an isocyanate compound is preferable, and among them, a polyisocyanate compound having at least three 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 xylylene diisocyanate (H6XDI), o- tolidine diisocyanate ( o- tolidine Diisocyanate, TOID), toluene diisocyanate (TDI) and other aromatic isocyanate compounds.

Examples of the trifunctional or higher isocyanate compound include biuret-type modifiers, isocyanurate-type modifiers of diisocyanates (compounds having two NCO groups in one molecule), and trimethylol groups. Adducts (polyol modifiers) of trivalent or higher polyhydric alcohols (compounds having at least 3 or more OH groups in one molecule) such as propane (TMP), glycerol, and the like.

The addition amount of the cross-linking agent may be determined in consideration of the type, degree of polymerization, functional group amount, and the like of the (meth) acrylic polymer. Although it is not particularly limited, it is usually made based on 100 parts by weight of the (meth) acrylic polymer The crosslinking agent is 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, it is preferable to add a crosslinking catalyst. 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 isocyanate-based cross-linking agent. Examples include amine compounds such as tertiary amines, and organotin. Compound Compounds, organic lead compounds, organic zinc compounds, organic iron compounds and the like.

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 amount of the crosslinking delaying agent is not particularly limited, it is relative to (meth) acrylic acid. 100 parts by weight of the enoic acid polymer is usually added at about 1.0 to 5.0 parts by weight.

In addition, a tackifier may be added to the adhesive as needed. Examples of the tackifier include rosin, benzofuran-indene, 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 the antistatic agent that can be used 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 is preferably a micro-adhesive having a slight adhesiveness with a peeling strength of about 0.05 to 0.5 N / 25 mm on the surface of the adherend. Floor. By forming a surface protective film for a transparent conductive film having such a micro-adhesive layer, it is possible to obtain excellent operability which is easy to peel 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, 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 the film and laminated. 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, it may be a method in which the adhesive layer 2 is coated on the base film 1 and the release film 3 is bonded after drying. Either a method, a method of applying the adhesive layer 2 on the release film 3, and a method of attaching the base film 1 after drying, and the like.

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

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 Mel bar coating method, or an air knife coating method, and the release agent is dried by heating, ultraviolet irradiation, or the like, Just solidify. 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 in which an adhesive film 4 is adhered 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 used in touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, In the technical fields such as liquid crystal panels, organic ELs, and solar cells, they are widely used for forming applications such as transparent electrodes.

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 type Polysiloxane (manufactured by Toray Dow Corning, product name: 100 parts by weight of SRX-211 was added with platinum catalyst SRX-212 (1 part by weight) and diluted with a toluene / ethyl acetate 1: 1 mixed solvent. 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 having a solid content of 40%, which is copolymerized with 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate. Adhesive composition obtained by adding 4 parts by weight of HDI-based cross-linking agent (manufactured by Japan Polyurethane Industry Co., Ltd., CORONATE HX) and 0.03 parts by weight of dibutyltin dilaurate as a cross-linking catalyst to 100 parts by weight of the product. . 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. The reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of this sample was 92%.

(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. The reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of this sample was 82%

(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 thickness of the adhesive layer was 40 μm. Of this sample The reaction rate K of the adhesive layer 15 minutes after the start of drying of the adhesive layer was 82%.

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

A surface protective film for a transparent conductive film of Example 4 was obtained in the same manner as in Example 1 except that the drying temperature of the adhesive layer was 120 ° C. The reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of this sample was 77%.

(Production of a surface protective film for a 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 set to 100 ° C. The reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of this sample was 56%.

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

In addition to the addition of HDI-based cross-linking agents (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 used as the adhesive composition Method to obtain a surface protective film for a transparent conductive film of Comparative Example 2. The reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer of this sample was 90%.

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

A surface protective film for a transparent conductive film of Comparative Example 3 was obtained in the same manner as in Comparative Example 2 except that the amount of the crosslinking agent added was 2 parts by weight based on 100 parts by weight of the acrylic polymer. 15 minutes after the drying of the adhesive layer of this sample started The reaction rate K of the adhesive layer was 74%.

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 reaction rate K)

An adhesive is applied to the film, and the solvent in the adhesive is dried in a hot-air circulation type oven, and then a release film is attached to the surface of the adhesive layer. After this sample was left for 15 minutes at 23 ° C and 50% RH, the release film was peeled off, and the infrared absorption spectrum of the surface of the adhesive layer was measured by Fourier transform infrared absorption spectrometry. Determination attributable to the isocyanate crosslinking agent (-N = C = O) 2270cm ^-1 to a peak intensity attributed to the binder (meth) acrylate C = O peak intensity of 1730cm ^-1, 2270 cm calculated The peak intensity ratio of ^-1 / 1730 cm ^-1 was taken as the peak intensity ratio (a) of the sample.

In the same way, the peak intensity when uncured is obtained as follows: without adding a cross-linking catalyst to the adhesive, dried in a hot air circulation oven at 80 ° C, and quickly (for example, within 1 minute) of the sample peak intensity adhesive layer 2270cm ^-1 / 1730cm ^-1, and the peak intensity as uncured ratio (b). The reaction rate K was determined by the following formula.

Reaction rate K (%) = (1-a / b) × 100

(Here, a is the peak intensity ratio of 2270cm ^-1 / 1730cm ^-1 obtained by Fourier transform infrared absorption photometry of the adhesive layer of the sample, and b is the Fourier transform infrared absorption photometry of the adhesive layer when it is not cured. (The obtained peak intensity ratio of 2270cm ^-1 / 1730cm ^-1 )

(Measurement of storage modulus)

After the samples obtained in the examples and comparative examples were aged in an oven at 40 ° C for 5 days, the storage of the adhesive layer at 30 ° C was measured using a viscoelasticity measuring device (manufactured by ABM Co., dynamic viscoelasticity measuring device Reogel-E4000). Modulus.

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

A PET film (manufactured by KIMOTO Corporation, 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 used 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. Other than that, it measured similarly to the measurement of the initial adhesive force, and this was made into the adhesive force (N / 25mm) after heating.

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

(Laminating a transparent conductive film surface to a hard-coated PET film How to check the handleability at the time of protective 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 part (positions approximately equidistant from both ends) of the transparent protective film surface protective film 50 m away 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. A surface protective film for a transparent conductive film was bonded to a hard-coated treatment surface of a hard-coated PET film (manufactured by KIMOTO, product name: KB film # 50G01), and then subjected to heat treatment 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. The outer surface of the hard-coated PET film Samples with apparent smoothness were evaluated as (○), samples with weak unevenness were evaluated as (Δ), and samples with strong uneven deformation were 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, and "Polymer B" is the acrylic polymer described in Comparative Example 2. 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 to 3, the reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer used in the surface protective film for a transparent conductive film was 82 to 92%, and the change in adhesive force before and after the heating process Is small, and the unevenness on the surface of the adhesive layer is very small (small). Good appearance of the hard-coated PET film using this surface protection film it is good. In addition, when the surface protective film for a transparent conductive film of Examples 1 to 3 was bonded to a hard-coated PET film, the handleability was also very good.

Regarding Example 4, the reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer was 77%, and the unevenness of the surface of the adhesive layer slightly increased compared with Examples 1 to 3. However, the uneven shape on the surface of the adhesive layer was not transferred to the hard-coated PET film, and a hard-coated PET film with good appearance was obtained.

On the other hand, in Comparative Example 1, the reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer used in the surface protective film for a transparent conductive film was as low as 56%. As a result, the surface protective film for the transparent conductive film of Comparative Example 1 had unevenness on the surface of the adhesive layer. When the laminated product obtained by laminating the hard-coated PET film was subjected to heat treatment, The uneven shape of the surface is transferred to the hard-coated PET film, and the appearance of the hard-coated PET film is reduced.

In addition, in Comparative Example 2, the storage modulus of the adhesive layer was as low as less than 4.0 × 10 ⁵ Pa, and the reaction rate K of the adhesive layer 15 minutes after the start of drying of the adhesive layer showed a value as high as 90%. However, the surface protective film for a transparent conductive film of Comparative Example 2 had irregularities on the surface of the adhesive layer. When a laminated product laminated with a hard-coated PET film was subjected to heat treatment, The uneven shape of the surface is transferred to the hard-coated PET film, and the appearance of the hard-coated PET film is reduced. Similarly, in Comparative Example 3, the storage modulus of the adhesive layer was as low as less than 4.0 × 10 ⁵ Pa, and the reaction rate K of the adhesive layer 15 minutes after the drying of the adhesive layer started was 74%. However, the surface protective film for a transparent conductive film of Comparative Example 3 had irregularities on the surface of the adhesive layer. When a laminated product laminated with a hard-coated PET film was subjected to heat treatment, The uneven shape of the surface is transferred to the hard-coated PET film, and the appearance of the hard-coated PET film is reduced.

[Industrial possibilities]

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 the operability and production efficiency of 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 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, and solar cells. Surface protection films for the manufacture and processing of thin films are widely used.

Claims (2)

A surface protective film for a transparent conductive film, which is used on the other surface of a transparent conductive film that is bonded to a resin film having a transparent conductive film formed on one surface. The surface of the transparent conductive film is characterized in that: The protective film has an adhesive layer. The adhesive layer is obtained by laminating an acrylic adhesive containing an isocyanate crosslinking agent and a crosslinking catalyst on one side of the substrate film. The adhesive layer is at 30 ° C. The storage modulus is 4.0 × 10 ⁵ Pa or more, and the reaction rate K of the isocyanate-based crosslinking agent contained in the adhesive layer 15 minutes after the adhesive layer is dried from the adhesive layer represented by the following formula is 15 minutes. It is 75% or more, and the reaction rate K (%) = (1-a / b) × 100, where a is obtained through the Fourier transform infrared absorption spectrophotometry of the adhesive layer 15 minutes after the drying of the adhesive layer is started. The peak intensity ratio of 2270cm ^-1 / 1730cm ^-1 , b is the peak intensity ratio of 2270cm ^-1 / 1730cm ^-1 obtained by Fourier transform infrared absorption photometry of the adhesive layer when uncured, and the isocyanates belonging to the group were measured. ^2270cm-1 peak of the isocyanate crosslinking agent (-N = C = O) of In the home of the binder (meth) acrylate after the C = O peak intensity of 1730cm ^-1, the formula by calculating the start of the adhesive layer was dried adhesive layer after 15 minutes contained The reaction rate K of the isocyanate-based crosslinking agent. A transparent conductive film is a transparent film obtained by bonding the surface protective film for a transparent conductive film described in item 1 of the patent application to the other surface of a resin film having a transparent conductive film formed on one surface. Conductive film.