TW201610080A - Surface-protective film for transparent conductive film, and transparent conductive film using the same - Google Patents

Abstract

The present invention provides a surface-protective film for a transparent conductive film in which an adhesive layer maintains smoothness of the surface, which has excellent handling properties even when attached on the transparent conductive film, which improves defects in appearance arising from the surface-protective film in the production and manufacturing and processing steps of the transparent conductive film, and which has good productivity in transparent electrode manufacturing steps for a touch panel and a transparent conductive film using the same. The present invention is a surface-protective film 5 for a transparent conductive film used by attached on the other surface of a transparent conductive film in which a transparent conductive film is formed on a surface of a resin film, wherein an adhesive layer 2 is laminated on one surface of a base film 1 by using an adhesive including an acrylic resin composition, a crosslinking agent, and a crosslinking catalyst, a storage modulus a of the adhesive layer at 30 DEG C is 4.0*105 Pa or more and the adhesive powers a and b with respect to a PET film of the adhesive layer after aging for 5 days at 40 DEG C satisfy the relationship of 0.9 ≤ a/b ≤ 2.0.

Description

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

The present invention relates to a surface protective film for a transparent conductive film which is bonded to the other surface of a resin film having a transparent conductive film formed on one surface thereof, 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, and the adhesive layer formed in the surface protective film for a transparent conductive film maintains the smoothness of the surface. Even when it is bonded to a transparent conductive film, it has excellent handleability, and in the manufacturing process of a transparent conductive film, the defect of the surface defect of the surface protection film is improved, and the manufacturing process of the transparent electrode of a touch panel is manufactured. The productivity is good.

In the technical fields of touch panels, electronic papers, electromagnetic 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. In the transparent conductive film, 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)) is formed on one surface of the substrate. .

In addition, in the process of the transparent electrode for a touch panel, a plurality of processes of the heating process and the reagent process are subjected to, for example, an annealing process for forming a transparent conductive film formed of a transparent conductive film made of ITO, AZO or GZO. The crystallization process of the metal oxide film, the printing process of the resist, the etching process, the process of forming the circuit wiring by using the silver paste, the printing process of the insulating layer, the punching process, and the like. In the process of the transparent electrode, in order to prevent the surface of the transparent conductive film from being on the opposite side of the surface on which the transparent conductive film is formed, the surface protective film for a transparent conductive film is bonded and used.

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

Various proposals have been made regarding a protective film for a transparent conductive film used in a process of a transparent electrode for a touch panel or the like. For example, Patent Document 1 proposes a surface protective film for a transparent conductive film provided with a binder layer on one surface of a substrate composed of a thermoplastic resin film having a melting point of 200 ° C or higher. It is considered that the heat resistance is better than that of the surface protective film for a transparent conductive film using a polyolefin resin such as polyethylene or polypropylene as a substrate.

Further, Patent Document 2 proposes a method for producing a surface protective film for a transparent conductive film, which comprises a substrate film containing a polyethylene terephthalate resin and/or a polyethylene naphthalate resin. After applying the adhesive on one side, at the specified temperature. Stay time. The tensile tension is dried. After the surface protective film for a transparent conductive film obtained by the above-described production method is bonded to the transparent conductive film, even if it is subjected to a heating process, no large curl is generated.

Patent Document 3 proposes a transparent conductive film and protection a resin film of a film in which a transparent conductive film is provided on one surface of a resin film, and a protective film is provided on a surface of the resin film opposite to the surface on which the transparent conductive film is provided, and the protective film is composed of a first film and a second film. And the first film and the second film are sequentially disposed on the resin film, and the heat shrinkage rate of the first film after heating at 150 ° C for 30 minutes is 0.5% or less in both the MD and TD directions, and the second film has the above The difference in linear expansion coefficient of the resin film having a transparent conductive film and a protective film is a linear expansion coefficient of 40 ppm/° C. or less. According to the invention, it is possible to obtain a transparent conductive film which is free from dimensional change and curl due to heat treatment in a processing such as touch panel formation.

Further, Patent Document 4 proposes a table for a transparent conductive film. The surface protective film is made to have a smooth surface of the adhesive layer of the surface protective film by using a release film having a predetermined thickness and bending resistance, and the appearance defect is improved.

[Prior Art Literature] [Patent Literature]

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

Patent Document 2: Japanese Patent No. 4342775

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

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

In the same manner as in the case of the patent document 4, the adhesive layer of the surface protective film maintains the smoothness of the surface and the surface protective film for a transparent conductive film having improved appearance defects. The surface protective film of Patent Document 4 is characterized in that a release film having a bending resistance of 0.30 mN to 40 mN at 40 ° C is used, but the bending resistance is obtained. The curved film has a problem that the thickness is increased and the cost is increased. Further, when the surface protective film is manufactured or when the user uses the surface protective film, the winding diameter of the surface protective film may be limited depending on the specifications of the processing machine to be used. In this case, as for the surface protective film using the release film having a thick substrate thickness, compared with the surface protective film using the release film having a thin substrate thickness, there is a problem that the diameter is rolled up by a predetermined winding diameter. The roll-up length becomes shorter, and the productivity in the transparent electrode process for the touch panel is degraded.

The present invention has been made in view of the above circumstances, and the object thereof is to provide A surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film, and a surface protective film for a transparent conductive film in a state of being rewinded from a roll, and a surface protective film for a transparent conductive film The layer maintains the smoothness of the surface, and has excellent handleability even when it is bonded to the transparent conductive film. In the process of manufacturing and processing the transparent conductive film, the surface defects of the surface protective film for the transparent conductive film are poor. Improved and good productivity in the transparent electrode process for touch panels.

The surface protective film for a transparent conductive film is produced by applying a binder to a base film or a release film, evaporating the solvent in the adhesive in a drying process, and then adhering the release film or the base film, and Rolled into a roll shape. As a result of intensive studies, the inventors have found that the cured state of the adhesive layer 15 minutes after the start of drying is related to the uneven deformation of the surface of the adhesive layer. Further, it has been found that the adhesive which is cured within 15 minutes after the start of drying by using the adhesive layer is used for the bonding of the adhesive layer having a thin substrate thickness to the adhesive layer for the transparent conductive film. In the case of the above, it is also possible to suppress The surface of the adhesive layer to be attached to the surface to be adhered is deformed by unevenness, thereby completing the present invention.

In the process of the surface protective film, the adhesive film is usually applied on the substrate film. After the mixture is dried and formed into a binder layer, it is aged in a roll state, but during the aging period, deformation of the release film occurs due to the influence of winding of the roll or the like. 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, and when the transparent conductive film is manufactured or processed, the appearance of the transparent conductive film becomes remarkable. The reason for the deterioration.

The technical idea of the present invention is as follows: a surface for a transparent conductive film When the protective film is aged in a roll shape, the adhesive layer is cured before the release film is deformed, whereby even if the release film is deformed, deformation of the surface of the adhesive layer can be suppressed, and smoothness can be maintained.

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

The present inventors have found that it is possible to grasp the progress state of the curing of the adhesive layer by comparing the force of the adhesive layer after the start of drying of the adhesive layer for 15 minutes and after the aging (aging). More specifically, if the adhesion of the adhesive layer is 15 minutes later and after the aging (aging) is completed, the ratio of the adhesion of the adhesive layer to the PET film (after the aging is completed, the adhesion is divided by 15 minutes after the start of drying). When the value obtained by the adhesive force is within a predetermined range, the peeling film having a thin substrate thickness is used for the bonding of the adhesive layer of the surface protective film for a transparent conductive film. In this case, it is also possible to suppress deformation in which the surface of the adhesive layer to be bonded to the adherend is uneven.

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 bonded to the other surface of a resin film having a transparent conductive film formed on one surface thereof, characterized in that the surface protective film for the transparent conductive film is on the substrate film The adhesive layer of the acrylic adhesive layer containing the acrylic resin composition, the crosslinking agent and the crosslinking catalyst is laminated on one side, and the storage modulus of the adhesive layer at 4.0 ° C is 4.0×10. ⁵ Pa or more, and the adhesion of the adhesive layer to the PET film after 15 minutes from the start of drying of the adhesive layer and the adhesion of the adhesive layer to the PET film after aging for 5 days at 40 ° C are satisfied. The relationship of the following formula (1).

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

Moreover, the present invention 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 resin film having a transparent conductive film formed on one surface thereof. .

The present invention provides a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film. The surface protective film for a transparent conductive film of the present invention is maintained in a state in which the adhesive layer is formed by rewinding from the roll. Smoothness of the surface, even when applied to a transparent conductive film, has excellent handleability. In the manufacturing process of the transparent conductive film, the defects of the appearance defects due to the surface protective film are improved, and the productivity in the transparent electrode process for a touch panel is good.

In addition, in recent years, as the casing of a high-function portable terminal such as a smart phone has become thinner, the thickness of the transparent conductive film to be used has been increasing. In the process for producing a transparent electrode for a touch panel, the surface protective film for a transparent conductive film of the present invention has a very small curl generated by a heating process even in a state of being bonded to a thin transparent conductive film. Thereby, the workability and production efficiency of the process of the transparent electrode for touch panels can be greatly improved.

1‧‧‧Base film

2‧‧‧Binder layer

3‧‧‧Release film

4‧‧‧Adhesive film

5‧‧‧Surface protective film for transparent conductive film

6‧‧‧ resin film

6a‧‧‧One side of the resin film

6b‧‧‧The other side of the resin film

7‧‧‧Transparent conductive film

10‧‧‧Transparent conductive film

11‧‧‧Laminated film

21‧‧‧Rolling roller

22‧‧‧Roller for substrate film

23‧‧‧Binder coating device

24‧‧‧ drying oven

25, 26‧‧‧ pressure roller

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

[Fig. 1] 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] Fig. 2 is a cross-sectional view showing an example in which a surface protective film for a transparent conductive film of the present invention is bonded to a transparent conductive film.

[Fig. 3] is a schematic view 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 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 a pressure-sensitive adhesive layer 2 laminated on one surface of a transparent flexible substrate film 1. The adhesive layer 2 is to be bonded to the surface of the adherend, and the release-treated release film 3 for protecting the surface of the adhesive layer is laminated by the peeled surface.

As the base film 1, a transparent flexible plastic film is used. Thus, the surface of the transparent conductive film for a transparent conductive film of the present invention can be directly bonded to the other surface of the transparent conductive film having the transparent conductive film formed on one surface of the substrate. The appearance of the film is checked. As the plastic film used as the substrate film 1, preferred are polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate. A polyester film such as a diester. Further, in addition to the polyester film, a plastic film of another resin type may be used as long as it is a plastic film having desired strength and optical compatibility. The base film 1 is an unstretched film, a unidirectional or biaxially stretched film, or the like, and is not particularly limited, but preferably has a low heat shrinkage ratio of the base film.

Further, the surface protection of the transparent conductive film according to the present invention The thickness of the base film 1 of the film is not particularly limited, and may be selected depending on the transparent conductive film to be used. When the thickness of the transparent conductive film to be used is 100 μm or more, the handleability of the transparent conductive film itself is not so bad. Therefore, the surface protective film mainly focuses on protecting the surface of the transparent conductive film. Therefore, a surface protective film having a thickness of the base film 1 of the surface protective film of about 25 to 75 μm can be used.

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

In addition, an adhesive layer may be laminated on the substrate film 1 as needed. An antifouling layer, an antistatic layer, an oligomer preventing layer, a hard coat layer for preventing damage, or a corona discharge layer laminated on the opposite surface of the surface of 2 to prevent surface fouling Treatment such as adhesion and anchor coating treatment.

The viscosity of the surface protective film for a transparent conductive film according to the present invention The mixture layer 2 is preferably an acrylic adhesive. In particular, a two-part type adhesive which is prepared (mixed) before the use of the acrylic adhesive and the crosslinking agent is preferred.

As an acrylic binder, in (meth)acrylic polymers It is preferable that a binder is added to the (acrylic resin composition) and a binder is added as needed. The (meth)acrylic polymer is usually a main monomer such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate or isodecyl acrylate with acrylonitrile, vinyl acetate or methyl methacrylate. Copolymerization of comonomers such as ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide, etc. The resulting polymer. The monomer composition constituting the (meth)acrylic polymer is preferably 50% or more of the (meth)acrylic monomer, and the (meth)acrylic monomer may be 100%.

As a crosslinking agent, an isocyanate compound and epoxidation are mentioned. A compound, a melamine compound, a metal chelate compound or the like, among which an isocyanate compound is preferred. Further, a polyisocyanate compound having at least two or more isocyanate (NCO) groups in one molecule is preferred.

The polyisocyanate compound may be classified into an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an aliphatic cyclic isocyanate, or the like, and may be any. Specific examples of the difunctional isocyanate compound include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). a compound; methylene diphenyl diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated dimethyl dimethyl diisocyanate (H6XDI), o- tolidine diisocyanate, An aromatic isocyanate compound such as TOID) or toluene diisocyanate (TDI).

Examples of the trifunctional or higher isocyanate compound include a biuret-type modified product of a diisocyanate (a compound having two NCO groups in one molecule) and a trimerized isocyanate-type modified product; and trimethylolpropane (TMP) An adduct (polyol modified product) of a trivalent or higher polyvalent alcohol (a compound having at least three or more OH groups in one molecule) such as glycerin.

The amount of cross-linking agent is considered as a (meth)acrylic polymer The type, the degree of polymerization, the amount of the functional group, and the like are not particularly limited, but the crosslinking agent is usually about 0.5 to 10 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

Further, the surface protection of the transparent conductive film according to the present invention When the film is aged in a roll shape, it is necessary to cure the adhesive layer before the release film is deformed. Therefore, in order to promote the crosslinking reaction between the (meth)acrylic polymer and the crosslinking agent, a crosslinking catalyst is added. Preferably. The crosslinking catalyst may be one which acts as a catalyst for the reaction (crosslinking reaction) of the (meth)acrylic polymer and the crosslinking agent, and when the polyisocyanate compound is used as the crosslinking agent, An organometallic compound such as an amine compound such as a tertiary amine, an organotin compound, an organic lead compound, an organozinc compound or an organic iron compound is used.

Examples of the tertiary amine include a trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, triethylene glycol diamine, and morpholin derivative. , piperazine derivatives, and the like.

The organotin compound may, for example, be a dialkyltin oxide, a fatty acid salt of a dialkyltin or a fatty acid salt of stannous.

The amount of the crosslinking catalyst to be added may be determined in consideration of the type of the (meth)acrylic polymer, the degree of polymerization, the amount of the functional group, the type of the crosslinking catalyst, the amount of addition, and the like, and is not particularly limited, and is polymerized with respect to the acrylic acid. 100 parts by weight of the substance is usually about 0.01 to 0.5 parts by weight.

In addition, in order to suppress the binder composition after the preparation of the crosslinking agent Excessive viscosity rise, gelation, and prolongation of the pot life of the adhesive composition may include a crosslinking retarder as needed.

Examples of the crosslinking retardation agent include β-keto acid such as methyl acetoacetate, ethyl acetate, octyl acetate, acetonitrile acetate, lauryl acetate, and stearyl acetate. a β-diketone such as ester, acetamidine acetone, 2,4-hexanedione or benzamidineacetone. In particular, it is preferably at least one selected from the group consisting of ethyl acetate and ethyl acetate. These crosslinking retardation agents are keto-enol tautomer compounds, and in the binder composition having a polyisocyanate compound as a crosslinking agent, the isocyanate group which is blocked by the crosslinking agent can inhibit the preparation of the crosslinking agent. The excessive viscosity and gelation of the adhesive composition can prolong the pot life of the adhesive composition.

The amount of the crosslinking retardation agent to be added is not particularly limited, and is usually about 1.0 to 5.0 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

In addition, an adhesive may be added to the adhesive as needed. Make Examples of the tackifier include rosin, benzofuran-quinone, terpene, petroleum, and phenol.

In addition, the surface of the transparent conductive film according to the present invention is protected by a surface. In the adhesive layer 2 of the film, an antistatic agent may be mixed as needed. The antistatic agent is preferably an antistatic agent which is dispersible in a (meth)acrylic polymer or which is compatible with a (meth)acrylic polymer. Examples of the antistatic agent that can be used include surfactants, ionic liquids, alkali metal salts, metal oxides, metal fine particles, conductive polymers, carbon, and carbon nanotubes. Surfactants, ionic liquids, alkali metal salts and the like are preferred from the viewpoints of transparency, affinity with a (meth)acrylic polymer, and the like. The amount of the antistatic agent to be added to the binder can be appropriately determined in consideration of the kind of the antistatic agent and the compatibility with the base polymer. In addition, the type of the antistatic agent and the addition of the antistatic agent are specifically set in consideration of the peeling voltage, the contamination of the adherend, the adhesive force, and the like which are required when the surface protective film for a transparent conductive film of the present invention is peeled off from the transparent conductive film. the amount.

Further, the surface protection of the transparent conductive film according to the present invention The thickness of the adhesive layer 2 of the film is not particularly limited, but is preferably, for example, a thickness of about 5 to 50 μm, and more preferably a thickness of about 5 to 30 μm. When the thickness of the adhesive layer 2 exceeds 50 μm, the cost of producing the surface protective film for a transparent conductive film increases, which impairs competitiveness. When the thickness of the adhesive layer 2 is less than 5 μm, there is a problem that the adhesion to the transparent conductive film is lowered, or when a surface protective film is bonded to the transparent conductive film, foreign matter is mixed therein, and transparent conductive is used. The film is greatly deformed.

Further, the adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention has a peel strength of about 0.05 to 0.5 N/25 mm on the surface of the adherend, and a micro-adhesive layer having a slight adhesiveness. good. By providing the surface protective film for a transparent conductive film having such a micro-adhesive layer, it is possible to obtain excellent workability which is easily peeled off from the adherend.

Further, the surface protection of the transparent conductive film according to the present invention The material of the release film 3 of the film is not particularly limited. The material of the release film which can be used is, for example, a polyolefin film such as a polyethylene film, a polypropylene film or a polymethylpentene film, or a release film using a polyoxyalkylene-based release agent or the like on the surface of a film such as a polyester film. The release film, the fluororesin film, the polyimide film, and the like which have been subjected to the release treatment are applied. Further, a film obtained by laminating a plurality of films using a bonding agent, a film obtained by melt-extruding a resin on a film, and laminating them may be used. A release treatment is performed on the single-layer film or the laminate film using a release agent such as a polyoxyalkylene-based release agent to obtain a release film.

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

When the release film 3 is thick, the entire length of the surface protective film for a transparent conductive film is shortened in the roll having the same winding diameter, and the manufacturing cost is increased. Therefore, the release film 3 needs to be guided to an appropriate thickness. Further, the release film 3 is preferably a release film obtained by subjecting a single-layer polyester film to a release treatment, and a release film obtained by subjecting a film obtained by laminating a plurality of polyester films to a laminate using a bonding agent.

Further, the adhesive layer 2 and the release film 3 are sequentially laminated on the substrate film 1. The method can be carried out by a known method, and is not particularly limited. Specifically, a method in which the adhesive layer 2 is applied onto the base film 1 and dried, and then the release film 3 is bonded, and the adhesive layer 2 is applied onto the release film 3 and dried, and then the base film 1 is bonded. Any of the methods and the like.

Further, the formation of the adhesive layer on the base film 1 can be carried out by a known method. Specifically, a reverse coating method, a comma coat method, a gravure printing method, a slit die coating method, a Mayer bar coat can be employed. A known coating method such as a method or an oven coat method.

Further, a method of performing a peeling treatment on the release film 3 is known. The method can be carried out. 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 coating method, or an oven coat method, and is heated or The release agent may be dried and solidified by ultraviolet irradiation or the like. The film to be subjected to the release treatment may be subjected to a pretreatment such as corona treatment, plasma treatment, or anchor coating to improve the adhesion of the release agent to the film.

2 is a surface showing a transparent conductive film of the present invention. A schematic configuration diagram of an example of the laminated film 11 in which a protective film is bonded to a transparent conductive film.

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

Examples of the transparent conductive film 10 include a polyethylene terephthalate (PET) film in which a transparent conductive film such as ITO, AZO, or GZO is formed, and a ring in which a transparent conductive film such as ITO, AZO, or GZO is formed. Polyolefin film and the like. Such a transparent conductive film is widely used for forming a transparent electrode or the like in a technical field such as a touch panel, an electronic paper, an electromagnetic wave shielding material, various sensors, a liquid crystal panel, an organic EL, or a solar cell.

The surface protective film for a transparent conductive film of the present invention exhibits an excellent effect of greatly improving the operation of a transparent electrode such as a touch panel. In terms of properties and production efficiency, even a thin transparent conductive film does not deteriorate workability and handleability.

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

The release film 3 and the base film 1 are repeatedly discharged from the roll 21 wound by the release film 3 subjected to the release treatment and the roll 22 wound by the base film 1. The adhesive is applied to one surface of the base film 1 by the adhesive coating device 23. The base film 1 coated with the adhesive is dried in a drying oven 24 to form an adhesive film 4. The surface of the adhesive film 4 on which the adhesive layer is formed is opposed to the surface of the release film 3 subjected to the release treatment, and is pressure-bonded by the 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 wound up on the drum 27. In general, the storage and transportation of the surface protective film 5 for a transparent conductive film are performed in the state of the drum 27. When bonded to the transparent conductive film 10, the surface protective film 5 for a transparent conductive film is rewinded from the drum 27.

[Examples]

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

(Production of Surface Protective Film for Transparent Conductive Film of Example 1)

On one side of the biaxially stretched polyester film having a thickness of 25 μm, the coating was applied by a Myrtle method to make the thickness of the dried polyoxyalkylene film 0.1 μm, and the coating was an addition reaction type. Polysiloxane (manufactured by Toray Dow Corning, product name: SRX-211 100 parts by weight, 1 part by weight of platinum catalyst SRX-212) was diluted with a toluene/ethyl acetate 1:1 mixed solvent. Further, the film was dried and solidified in a hot air circulating oven at a temperature of 120 ° C for 1 minute to obtain a release film of Example 1.

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

(Production of Surface Protective Film for Transparent Conductive Film of Example 2)

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

(Production of Surface Protective Film for Transparent Conductive Film of Example 3)

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

(Production of Surface Protective Film for Transparent Conductive Film of Comparative Example 1)

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

(Production of Surface Protective Film for Transparent Conductive Film of Comparative Example 2)

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

(Production of Surface Protective Film for Transparent Conductive Film of Comparative Example 3)

In addition to using 100 parts by weight of an acrylic polymer having a solid content of 40% copolymerized with 2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate, an HDI crosslinking agent (Japanese polyurethane) is added. The adhesive composition obtained by the industrial company, the product name: CORONATE HX), and the binder composition obtained by mixing and mixing 0.03 part by weight of dibutyltin dilaurate as a crosslinking catalyst as a binder composition, the same as in the first embodiment. In the manner of obtaining a surface protective film for a transparent conductive film of Comparative Example 3.

(Production of Surface Protective Film for Transparent Conductive Film of Comparative Example 4)

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

Hereinafter, the method and test results of the evaluation test are shown. Here, The "hard coating-treated PET film" is used as an example of a substrate (film) for a transparent conductive film.

(Measurement of storage modulus)

For the samples obtained in the examples and the comparative examples, the viscoelasticity measuring apparatus (manufactured by ABM, dynamic viscoelasticity measuring apparatus Reogel-E4000) was used to measure the storage of the adhesive layer after curing for 5 days at 40 ° C for 30 days. Modulus.

(Measurement of adhesion to PET film)

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

The sample was attached to a biaxially stretched polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Inc., DIA FOIL T100) having a thickness of 38 μm by reciprocating a 2 kg rubber roller. After being allowed to stand in an environment of 23° C. and 50% RH for 1 hour, the PET film was peeled off in a direction of 180° at a peeling speed of 300 mm/min using a small table type test apparatus (EZ-L, manufactured by Shimadzu Corporation). Adhesion.

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

A PET film which was subjected to a hard coating treatment on a single surface of a biaxially stretched polyester film having a thickness of 50 μm and which was also used for hard coating treatment of an ITO film (manufactured by KIMOTO Co., Ltd., product name: KB film # 50G01). The transparent conductive film cut into a 25 mm-wide transparent conductive film was bonded to the surface of the PET film subjected to the hard coating treatment, and then stored in an environment of 23 ° C and 50% RH for 1 hour to prepare an initial bond. The sample of the force is measured. Then, the strength at the time of peeling the surface protective film for transparent conductive films in the direction of 180 degrees at a peeling speed of 300 mm/min was measured using a tensile tester, and this was made into the initial adhesive force (N / 25 mm).

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

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

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

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

(Method for confirming the handleability when a surface protective film for a transparent conductive film is bonded to a hard coating-treated PET film)

A sample subjected to visual inspection of the surface protective film for a transparent conductive film was used as the surface protective film for a transparent conductive film described below. The surface protective film for a transparent conductive film was bonded to the hard-coated surface of the PET film (KIMOTO Co., Ltd., product name: KB film #50G01) after the hard coating process, and the laminated product was cut into the A4 size. One of the four corners of the cut sample was taken and vibrated back and forth 20 times in such a manner that the film surface was fanned in the air. Then, it was confirmed by visual observation whether or not the PET film of the hard coating treatment was bent or deformed. The sample which was not bent and deformed on the hard-coated PET film was evaluated as (○), and the sample which was bent or deformed was evaluated as (×).

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

A roll of a surface protective film for a transparent conductive film (400 mm width × 100 m/volume) was produced by a test coater, and the mixture was kept in an oven at 40 ° C for 5 days to cure the adhesive. Then, the appearance of the sample of the surface protective film for the transparent conductive film after the rewinding of the roll product from the edge 50 m from the edge (a position equidistant from both ends) was observed by visual observation. The sample having a smooth surface of the adhesive layer was evaluated as (○), and a sample having weak unevenness on the surface of the adhesive layer was evaluated as (Δ), and a sample having strong unevenness on the surface of the adhesive layer was evaluated as ( ×).

(Method of visual inspection of hard coating film)

A sample subjected to visual inspection of the surface protective film for a transparent conductive film was used as the surface protective film for a transparent conductive film described below. The surface protective film for transparent conductive films was bonded to the hard-coated surface of the hard-coated PET film (KIMOTO Co., Ltd., product name: KB film #50G01), and then heat-treated at 150 ° C for 1 hour. After the surface protective film for the transparent conductive film was peeled off, the surface state of the hard coating-treated PET film was visually observed. The sample having a smooth appearance of the hard-coated PET film was evaluated as (○), the sample having the uneven deformation of the uneven shape was evaluated as (Δ), and the sample having the uneven deformation 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 2, and "Polymer C" is described in Comparative Example 3. The acrylic polymer, "crosslinking agent 1" is the HDI crosslinking agent described in Example 1 and Comparative Example 3, and the "crosslinking agent 2" is the epoxy crosslinking agent described in Comparative Example 2. Further, the value of the storage modulus in Table 1 is expressed by the form of the mantissa and the index before and after E, and for example, 4.0 × 10 ^{5 is} recorded as 4.0E+05.

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

In the adhesive layers used for the surface protective film for transparent conductive films in Examples 1 and 2, the ratio of the adhesive force to the PET film after 15 minutes from the start of drying of the adhesive layer and after aging at 40 ° C for 5 days "(a/b) is 1.4 to 1.6, and the change in the adhesive force after completion of aging (aging) after 15 minutes from the start of drying is small, and the unevenness on the surface of the adhesive layer is extremely small. The hard coating-treated PET film using the surface protective film had a good appearance. In addition, the handleability when the surface protective film for transparent conductive films of Examples 1-2 was bonded to the hard-coating PET film was also excellent.

With respect to Example 3, "the ratio of the adhesive force to the PET film after 15 minutes from the start of drying of the adhesive layer to the temperature at 40 ° C for 5 days" (a/b) was 2.0, which was compared with Examples 1 and 2. The unevenness on the surface of the adhesive layer was slightly increased, but 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 having a good appearance was obtained.

On the other hand, for Comparative Examples 1 and 2, "the dryness of the adhesive layer was opened. After the first 15 minutes, the ratio of the adhesion to the PET film after the aging for 5 days at 40 ° C (a/b) was 2.3 to 8.5, and the surface protective film for the transparent conductive film was uneven on the surface of the adhesive layer. Therefore, when the laminate which is bonded to the hard coating-treated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard coat layer. On the cloth treated PET film, the appearance of the hard coating treated PET film was lowered.

Further, in Comparative Example 3, the storage modulus of the adhesive layer was as low as less than 4.0 × 10 ⁵ Pa, and the ratio of the adhesion to the PET film after 15 minutes from the start of drying of the adhesive layer and after aging at 40 ° C for 5 days. (a/b) is 1.5. However, the surface protective film for a transparent conductive film of Comparative Example 3 produced irregularities on the surface of the adhesive layer. Therefore, when heat-treating the laminated product bonded to the hard-coated PET film, the uneven shape of the surface of the adhesive layer is transferred to the hard-coated PET film, and the PET film is hard-coated. The appearance is declining.

In Comparative Example 4 in which no crosslinking catalyst was added, the adhesion of the adhesive layer was evaluated in the adhesion of the PET film 15 minutes after the start of drying of the adhesive layer, and the surface protective film for the transparent conductive film was on the adhesive layer. The surface produces bumps. Therefore, when the laminate obtained by laminating the hard-coated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred onto the hard-coated PET film, and the appearance of the hard-coated PET film is applied. decline.

[Industrial Applicability]

In the process for producing a 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. . Thereby, the workability and production efficiency of the process of the transparent electrode for touch panels can be greatly improved. Further, 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 of touch panels, electronic paper, electromagnetic wave shielding materials, various sensors, liquid crystal panels, organic EL, solar cells, and the like. A surface protective film for the production and processing of a film is widely used.

1‧‧‧Base film

2‧‧‧Binder layer

3‧‧‧Release film

4‧‧‧Adhesive film

5‧‧‧Surface protection film for transparent conductive film

Claims (2)

A surface protective film for a transparent conductive film, which is used for bonding to a surface of a resin film having a transparent conductive film formed on one surface thereof, characterized in that the surface protective film for the transparent conductive film is on a substrate The adhesive layer of the acrylic adhesive layer containing the acrylic resin composition, the crosslinking agent and the crosslinking catalyst is laminated on one side of the film, and the storage modulus of the adhesive layer at 30 ° C is 4.0 × 10 ⁵ Above Pa, and the adhesion of the adhesive layer to the PET film after 15 minutes from the start of drying of the adhesive layer and the adhesion of the adhesive layer to the PET film after aging for 5 days at 40 ° C satisfy the following formula (1) )Relationship: Where a is the adhesion of the adhesive layer to the PET film 15 minutes after the start of drying of the adhesive layer, and b is the adhesion of the adhesive layer to the PET film after aging at 40 ° C for 5 days. A transparent conductive film obtained by laminating a surface protective film for a transparent conductive film according to claim 1 of the invention to the other surface of a resin film having a transparent conductive film formed on one surface thereof Conductive film.