TW201606039A - 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 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 attaching 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 laminated on one surface of a base film 1 is formed 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 after aging for 5 days at 40 DEG C is 4.0*10<SP>5</SP> Pa and a storage modulus b at 30 DEG C of the adhesive layer 15 minutes after the start of drying and a satisfy the relationship of 0.9 ≤ a/b ≤ 1.3.

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 surface smoothness. Even when it is bonded to a transparent conductive film, it has excellent handleability, and in the process of manufacturing and processing a transparent conductive film, the defect of the appearance of the surface protective film is improved, and it is manufactured by the transparent electrode for a touch panel. The productivity in the process 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 a transparent electrode or the like. 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 manufacturing 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, annealing of the transparent conductive film formed with the transparent conductive film composed 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 manufacturing process of such a transparent electrode, in order to prevent contamination or damage on the opposite side surface of the surface of the transparent conductive film on which the transparent conductive film is formed, a surface protective film for a transparent conductive film is bonded and used.

In the manufacturing process of the transparent electrode, 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 for a protective film for a transparent conductive film used in a manufacturing 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. This is superior to the surface protective film for a transparent conductive film using a polyolefin resin such as polyethylene or polypropylene as a base material.

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, it is dried at a predetermined temperature ‧ dwell time ‧ tensile tension It is considered that the surface protective film for a transparent conductive film obtained by the production method does not cause a large curl even after a heating process after being bonded to the transparent conductive film.

Patent Document 3 proposes a resin film having a transparent conductive film and a protective film, wherein a transparent conductive film is provided on one surface of the resin film, and protection is provided on the surface of the resin film opposite to the surface on which the transparent conductive film is provided. a film, wherein the protective film is composed of a first film and a second film, and the first film and the second film are sequentially disposed from the resin film, and the heat shrinkage rate of the first film after heating at 150 ° C for 30 minutes is in MD and TD The direction is 0.5% or less in the direction, and the second film has a coefficient of linear expansion which is 40 ppm/° C. or less from the linear expansion coefficient of the resin film having the transparent conductive film and the protective film. According to the invention, it is possible to obtain a transparent conductive film which does not undergo dimensional change and curl due to heat treatment in a processing such as touch panel formation.

Further, Patent Document 4 proposes a surface protective film for a transparent conductive film which is formed by smoothing the surface of the adhesive layer of the surface protective film by using a peeling film having a predetermined thickness and bending resistance, and the appearance defect is improved.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open 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 Patent Laid-Open 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 by use The peeling resistance at 40 ° C is a peeling film of 0.30 mN to 40 mN, but the film having such bending resistance 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 wound at a predetermined winding diameter. The winding length at the time of starting is shortened, and the productivity in the manufacturing process of the transparent electrode for a touch panel is lowered.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a surface protective film for a transparent conductive film and a transparent conductive film using the surface protective film, and the surface protective film for a transparent conductive film is rewinded from the drum. The adhesive layer of the surface protective film for a transparent conductive film maintains the smoothness of the surface, and has excellent handleability even when it is bonded to the transparent conductive film. In the manufacturing process of the transparent conductive film, the process is caused by The surface defects of the surface protective film for a transparent conductive film are improved, and the productivity in the transparent electrode manufacturing process for a touch panel is good.

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 surface of the transparent conductive film even if the release film having a small thickness of the substrate is used. In the case of the bonding application of the adhesive layer of the protective film, the deformation of the surface of the adhesive layer to be adhered to the adherend can be suppressed, and the present invention has been completed.

In the manufacturing process of the surface protective film, the adhesive is usually applied to the base film and dried to form a binder layer, and then cured in a roll state, but during the ripening period, it may be due to the roll. The deformation of the release film occurs due to the influence of shrinkage 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 to suppress the curing of the adhesive layer before the release film is deformed while the surface protective film for a transparent conductive film is cured in a roll shape, thereby suppressing deformation of the release film. The surface of the adhesive layer is deformed to maintain smoothness.

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

The present inventors have found that the state of curing of the adhesive layer can be grasped by comparing the storage modulus 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 ratio of the storage modulus after the start of drying (aging) after 15 minutes from the start of drying of the adhesive layer (the storage modulus after completion of aging is divided by the storage modulus after 15 minutes from the start of drying) The value of the substrate is within a predetermined range, even in the case of a thin film having a thin substrate thickness When the adhesive layer for the surface protective film for transparent conductive films is used for bonding, it is also possible to suppress deformation of the surface of the adhesive layer to be adhered to the adherend.

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

A surface protective film for a transparent conductive film which is bonded to the other surface of a resin film having a transparent conductive film formed on one surface thereof, wherein the surface protective film for a transparent conductive film is a substrate film The adhesive layer is formed by laminating a pressure-sensitive adhesive layer on one side, and the adhesive layer is formed by using an adhesive containing an acrylic resin composition, a crosslinking agent and a crosslinking catalyst, and aging at 40 ° C for 5 days. The storage modulus of the adhesive layer at 30 ° C is 4.0×10 ⁵ Pa or more, and the storage modulus of the adhesive layer at 30° C. after drying the adhesive layer for 15 minutes is at 40° C. The storage modulus of the adhesive layer after aging for 5 days at 30 ° C satisfies the relationship of the following formula (1).

0.9 a/b 1.3 formula (1)

(here, a is the storage modulus of the adhesive layer after aging for 5 days at 40 ° C at 30 ° C, and b is the adhesive layer after drying the adhesive layer for 15 minutes at 30 Storage modulus at °C)

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, and the transparent conductive film of the present invention In the state in which the surface protective film is rewinded from the drum, the formed adhesive layer maintains the smoothness of the surface, and has excellent handleability even when it is bonded to the transparent conductive film, and is manufactured and processed in the transparent conductive film. Among them, the defect of the appearance defect due to the surface protective film is improved, and the productivity in the manufacturing process of the transparent electrode for a touch panel is good.

In addition, in recent years, as the 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. 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 in which it is bonded to a thin transparent conductive film in a manufacturing process of a transparent electrode for a touch panel. . Thereby, the workability and production efficiency of the manufacturing process of the transparent electrode for touch panels can be greatly improved.

1‧‧‧Base film

2‧‧‧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. Laminated adhesive layer 2 Adhered to the surface of the adherend, the 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 base film 1, preferred are polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polypair. A polyester film such as polybutylene terephthalate. 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 uniaxial or biaxially stretched film, or the like, and is not particularly limited, but the heat shrinkage rate of the base film is preferably low.

Further, 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 may be selected depending on the transparent conductive film to be used. When the transparent conductive film to be used has a thickness of 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, when the transparent conductive film to be used is as thin as 50 μm or less, the handleability of the transparent conductive film itself is inferior, and therefore, the handleability of the surface protective film is also considered, and the thickness of the base film is thick. A transparent conductive film is preferred. The thickness of the specific base film is preferably about 100 to 188 μm.

Further, an antifouling layer, an antistatic layer, an oligomer preventing layer, and damage prevention for the purpose of preventing surface fouling on the opposite side surface of the surface of the base film 1 on which the adhesive layer 2 is laminated may be laminated as needed. The hard coat layer is subjected to an easy adhesion treatment such as a corona discharge treatment or an anchor coating treatment.

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

As the acrylic binder, a binder is added to the (meth)acrylic polymer (acrylic resin composition), and a binder to which a tackifier is added as needed is preferable. 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 (meth)acrylic polymer constituting the (meth)acrylic polymer is preferably 50% or more, and the (meth)acrylic monomer may be 100%.

The crosslinking agent may, for example, be an isocyanate compound, an epoxy compound, a melamine compound or a metal chelate compound, and among them, 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 is classified into an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an alicyclic isocyanate, or the like, and may be any of them. Specific examples of the difunctional isocyanate compound include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). Compound; methylene diphenyl diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated dimethylene diisocyanate (H6XDI), o-toluene diisocyanate ( o- tolidine) An aromatic isocyanate compound such as Diisocyanate, 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 the crosslinking agent 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, and the like, and is not particularly limited, and is usually 100 parts by weight based on the (meth)acrylic polymer. The crosslinking agent is made to be about 0.5 to 10 parts by weight.

Further, in the surface protective film for a transparent conductive film according to the present invention, it is necessary to cure the adhesive layer before the release film is deformed while being cured in a roll shape, and therefore, in order to promote the (meth)acrylic polymer In the crosslinking reaction with the crosslinking agent, it is preferred to add a crosslinking catalyst. 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 amine compound such as a tertiary amine, an organotin compound, an organic lead compound, an organozinc compound, or an organic metal compound such as an organic iron compound is obtained.

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 relative to the acrylic. The polymer is usually used in an amount of from 0.01 to 0.5 parts by weight per 100 parts by weight.

Further, in order to suppress excessive viscosity increase, gelation, and prolongation of the pot life of the adhesive composition after the preparation of the crosslinking agent, a crosslinking retardation agent may be contained 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, by blocking the isocyanate group of the crosslinking agent, it is possible to suppress 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 rosins, benzofurans, terpenes, petroleums, and phenols.

Further, in the adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention, an antistatic agent may be mixed as needed. As the antistatic agent, an antistatic agent which is excellent in dispersibility in a (meth)acrylic polymer or compatibility with a (meth)acrylic polymer is preferable. 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 is specifically set in consideration of the required peeling static voltage, the contamination of the adherend, the adhesive force, and the like when the surface protective film for a transparent conductive film according to the present invention is peeled off from the transparent conductive film. , the amount added.

In addition, 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, and is preferably a thickness of, for example, about 5 to 50 μm, and 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. A micro-adhesive layer having a slight adhesiveness is preferred. 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 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 a polyolefin film such as a polyethylene film, a polypropylene film, or a polymethylpentene film, and 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, and a laminated 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 type release agent to obtain a release film.

Further, 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 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 roll diameter, and the manufacturing cost is increased. Therefore, the release film 3 is 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.

In addition, the method of laminating the adhesive layer 2 and the peeling film 3 in this order on the base film 1 can be carried out by a well-known method, and is not specifically 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 known coating method such as a reverse coating method, a comma coating method, a gravure printing method, a slit die coating method, a Meyer bar coating method, or an air knife coating method can be employed.

Further, the method of performing the release treatment on the release film 3 may be carried out by a known method. Specifically, a release agent is applied to one surface of the release film 3 by a coating method such as a gravure printing method, a Mayer bar coating method, or an air knife coating method, and is heated or irradiated with ultraviolet rays or the like. The release agent can be dried and solidified. 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.

In addition, FIG. 2 is a schematic configuration diagram showing an example of a laminated film 11 obtained by bonding a surface protective film for a transparent conductive film of the present invention 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 a surface protective film for a transparent conductive film of the present invention. 5 is obtained by peeling off the release film 3. 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 transparent electricity in touch panel, electronic paper, electromagnetic wave shielding material, various sensors, liquid crystal panels, organic EL, solar cells, and the like. The formation of the poles.

The surface protective film for a transparent conductive film of the present invention exhibits an excellent effect of greatly improving workability and production efficiency in a manufacturing process of a transparent electrode such as a touch panel, and even a thin transparent conductive film. It does not reduce workability and handling.

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 continuously discharged from the roll 21 obtained by winding 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 as 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 polysiloxane film to be 0.1 μm, and the coating was an addition reaction. Type polyoxyalkylene (manufactured by Toray Dow Corning, product name: SRX-211 100 parts by weight added with platinum catalyst SRX-212 1 part by weight) with toluene / A coating obtained by diluting 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.

Further, the adhesive layer is formed using a binder composition which is an acrylic polymer 100 having a solid content of 40% obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate. To the parts by weight, 4 parts by weight of an HDI-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name: CORONATE HX), and 0.03 parts by weight of dibutyltin dilaurate as a crosslinking catalyst were added and mixed. 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 dried in a hot air circulating oven at a temperature of 130 ° C. 1 minute. Then, the poly silicon film is peeled alumoxane Example 1 produced above (Silicone) treated surface bonded to the upper surface of the laminate adhesive layer, a surface protection film obtained 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 drying temperature of the adhesive layer was 120 °C.

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

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

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

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

(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-based 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)

An epoxy-based crosslinking agent is added to 100 parts by weight of an acrylic polymer having a solid content of 40% obtained by copolymerizing butyl acrylate, 2-ethylhexyl acrylate and acrylic acid (Mitsubishi Gas Chemical Co., Ltd., product name) In the same manner as in Example 1, 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 the binder composition obtained by mixing the mixture of TETRAD-C) was used.

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, a viscoelasticity measuring device was used. (Remogel-E4000, manufactured by ABM, Dynamic Resilience Measuring Device Reogel-E4000) The storage modulus (b) of the adhesive layer at 30 ° C after 15 minutes from the start of drying of the adhesive layer and 5 days after curing at 40 ° C. The storage modulus (a) of the adhesive layer at 30 °C.

In the following Table 1, the storage modulus (b) is abbreviated as "the storage modulus (b) before aging), and the storage modulus (a) is abbreviated as "the storage modulus after curing (a)", The ratio (a/b) of both is abbreviated as "proportion after maturity/pre-maturing (a/b)".

(Measurement of Initial Adhesive Force of Surface Protective Film for Transparent Conductive Film)

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. In addition to this, initial bonding The measurement of the force was measured in the same manner, and this was taken as the adhesive force after heating (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 inspection 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. Treating PET in hard coating A surface protective film for a transparent conductive film was bonded to a hard coating surface of a film (manufactured by 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 3, and "Polymer C" is described in Comparative Example 4. The acrylic polymer, "crosslinking agent 1" is the HDI-based crosslinking agent described in Example 1, and "crosslinking agent 2" is the epoxy-based crosslinking agent described in Comparative Example 4. 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 in the surface protective film for transparent conductive films in Examples 1 and 2, "the storage modulus of the adhesive layer after 15 minutes from the start of drying of the adhesive layer at 30 ° C and at 40 ° C The ratio of the storage modulus of the adhesive layer after aging for 5 days at 30 ° C (a/b) is 1.0 to 1.2, the change of the adhesive force before and after the heating process is small, and the unevenness of the surface of the adhesive layer is very small ( 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.

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

On the other hand, in Comparative Example 1 in which the crosslinking catalyst was not added, the adhesive layer used for the surface protective film for a transparent conductive film, "the adhesive layer after the start of drying of the adhesive layer for 15 minutes at 30 ° C The ratio of the storage modulus of the adhesive layer to the storage modulus at 30 ° C after 5 days of aging at 40 ° C (a/b) is 27.5, and the surface protective film for the transparent conductive film is on the adhesive layer. The surface has irregularities. 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 2, the ratio of the storage modulus of the adhesive layer at 30 ° C after 15 minutes from the start of drying of the adhesive layer to the storage modulus of the adhesive layer at 30 ° C after aging for 5 days at 40 ° C (a/b) is 1.5, and the surface protective film for transparent conductive films has unevenness on the surface of the adhesive layer. Therefore, in the treatment of PET with hard coating When the laminate obtained by laminating the film is subjected to heat treatment, the uneven shape on the surface of the adhesive layer is transferred to the hard-coated PET film, and the appearance of the hard-coated PET film is lowered.

Further, in Comparative Example 3 in which the adhesive layer having a low storage modulus was used, "the storage modulus of the adhesive layer after 30 minutes from the start of drying of the adhesive layer at 30 ° C and after aging at 40 ° C for 5 days" The ratio (a/b) of the storage modulus at 30 ° C of the adhesive layer was 1.1, but the surface protective film for a transparent conductive film of Comparative Example 3 had 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, the adhesive used in the surface protective film for a transparent conductive film, "the storage modulus of the adhesive layer after 15 minutes from the start of drying of the adhesive layer at 30 ° C and the aging at 40 ° C for 5 days" The ratio (a/b) of the storage modulus of the adhesive layer at 30 ° C was 10.0, and the surface protective film for a transparent conductive film 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.

[Industrial Applicability]

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 in which it is bonded to a thin transparent conductive film in a manufacturing process of a transparent electrode for a touch panel. . Thereby, the workability and production efficiency of the manufacturing process of the transparent electrode for touch panels can be greatly improved. Further, the surface protective film for a transparent conductive film of the present invention can be used as a touch panel, an electronic paper, an electromagnetic wave shielding material, various sensors, a liquid crystal panel, Surface protective films for the production and processing of transparent conductive films used in the technical fields such as organic EL and solar cells are widely used.

1‧‧‧Base film

2‧‧‧Binder layer

3‧‧‧Release film

4‧‧‧Adhesive film

5‧‧‧Surface protective 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 is formed by laminating a pressure-sensitive adhesive layer on one side of the film, and the adhesive layer is formed by using an adhesive containing an acrylic resin composition, a crosslinking agent, and a crosslinking catalyst, and the adhesion is performed after aging at 40 ° C for 5 days. The storage modulus of the agent layer at 30 ° C is 4.0×10 ⁵ Pa or more, and the adhesive layer of the adhesive layer after drying for 15 minutes is stored at 30° C. and aged at 40° C. for 5 days. The storage modulus of the subsequent adhesive layer at 30 ° C satisfies the relationship of the following formula (1): 0.9 a/b 1.3 Formula (1) wherein a is the storage modulus of the adhesive layer at 30 ° C after aging for 5 days at 40 ° C, and b is the adhesive layer after drying the adhesive layer for 15 minutes at 30 ° C. The storage modulus under. A transparent conductive film obtained by bonding a surface protective film for a transparent conductive film according to claim 1 to the other surface of a resin film having a transparent conductive film formed on one surface thereof Sex film.