TW201610079A - 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 is laminated on one surface of a base film 1 by using an acrylic-based including an isocyanate crosslinking agent and crosslinking catalyst, a storage modulus a of the adhesive layer at 30 DEG C is 4.0*10<SP>5</SP> Pa or more and a reaction rate K of the adhesive layer 15 minutes after the start of drying of the adhesive layer is 75% or more.

Description

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

The present invention includes 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 defects in the appearance of the surface protective film are improved in the production and processing of the transparent conductive film, and the transparent electrode process for the touch panel is improved. 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 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 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 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. 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, it is dried at a predetermined temperature ‧ dwell time ‧ tensile tension 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 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 curling 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 made to have a smooth surface of the adhesive layer of the surface protective film by using a peeling film having a predetermined thickness and bending resistance, and the defect of the appearance 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

According to the present invention, in the same manner as in Patent Document 4, the adhesive layer of the surface protective film maintains the smoothness of the surface and the transparent defect of the appearance defect is improved. A surface protective film for electrical films. The surface protective film of Patent Document 4 is characterized in that a release film having a bending resistance at 40° C. of 0.30 mN to 40 mN is used. However, 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 it is rolled up at a predetermined winding diameter. The roll-up length at the time is shortened, and the productivity in the manufacturing process of the transparent electrode for the 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 a 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, and is caused by transparent conductive in the production process of the transparent conductive film. The defect of the appearance of the surface protective film for a film is improved, and the productivity in the transparent electrode process for a touch panel is favorable.

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, bonding the release film or the base film, and rolling the film. In the shape of a roller. 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 was found that the adhesive layer was cured by using the adhesive layer within 15 minutes after the start of drying. In the case where the release film having a small thickness of the substrate is used for the bonding application of the adhesive layer of the surface protective film for a transparent conductive film, it is possible to suppress the adhesion of the adhesive layer to be adhered. The surface on the object is deformed by unevenness, thereby completing the present invention.

In the process of the surface protective film, the adhesive is usually applied to the base film and dried to form a binder layer, and then matured in a roll state, but during the ripening period, the roll is rolled up. The deformation of the release film occurs immediately after the influence. Therefore, when the adhesive layer is cured after the release film is deformed, the surface shape of the release film is transferred to the surface of the adhesive layer, and when the transparent conductive film is manufactured or processed, the appearance of the transparent conductive film is 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 other words, while the surface protective film for a transparent conductive film according to the present invention is lapped in a roll shape, the adhesive layer is formed before the adhesive layer in which the release film is bonded is deformed by the deformation of the release film. The curing prevents unevenness on the surface of the adhesive layer attached to the adherend, thereby maintaining smoothness.

The present inventors have found that the progress of curing of the adhesive layer can be grasped by measuring the reaction rate of the adhesive layer after 15 minutes from the start of drying of the adhesive layer and the storage modulus of the adhesive layer after completion of aging (aging). More specifically, if the reaction rate of the adhesive layer after 15 minutes from the start of drying of the adhesive layer and the storage modulus of the adhesive layer after completion of aging (aging) are within a predetermined range, even in When the release film having a small thickness of the substrate is used for the bonding application of the adhesive layer of the surface protective film for a transparent conductive film, it is also possible to suppress the occurrence of the surface of the adhesive layer to be bonded to the adherend. Deformation of the bumps.

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

A surface protective film for a transparent conductive film, which is used for bonding to a 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 has a base film An adhesive layer obtained by laminating an acrylic adhesive containing an isocyanate crosslinking agent and a crosslinking catalyst on one surface of the material film, the storage modulus of the adhesive layer at 30 ° C is 4.0 × 10 ⁵ Pa As described above, the reaction rate K of the adhesive layer after the start of drying of the adhesive layer represented by the following formula in the adhesive layer is 75% or more.

Reaction rate K (%) = (1-a / b) × 100

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

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 a surface for a transparent conductive film of the present invention In the state in which the 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. The defect due to the appearance of the surface protective film is improved, and the productivity is good in the manufacturing process of the transparent electrode for a touch panel.

In addition, in recent years, as the 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. Adhesive layer 2 to be laminated On the surface of the adherend, the release-treated release film 3 for protecting the surface of the adhesive layer is laminated on the surface to be peeled off.

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, for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polyparaphenylene is preferable. 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 coat treatment.

The adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention is preferably an acrylic adhesive. Among them, an acrylic adhesive using an isocyanate crosslinking agent and a crosslinking catalyst is preferred. When the surface of the transparent conductive film is used to protect the transparent conductive film, the adhesive having a small change in the adhesive force before and after the heat treatment is not particularly limited. The composition of the acrylic adhesive is not particularly limited, and a known one can be used. material.

As the acrylic binder, a binder to which a crosslinking agent is added to a (meth)acrylic polymer (acrylic resin composition) and to which a tackifier is added 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. Copolymerizable monomers such as ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide and other functional monomers Polymer. The (meth)acrylic monomer having a preferred monomer composition of the (meth)acrylic polymer is 50% or more, and the (meth)acrylic monomer may be 100%.

The crosslinking agent is preferably an isocyanate compound, and a polyisocyanate compound having at least three 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 aliphatic cyclic 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). a compound; methylene diphenyl diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated 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 modified isocyanurate type; and a trimethylol group; 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 propane (TMP) or 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 made with respect to 100 parts by weight of the (meth)acrylic polymer. The crosslinking agent is 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 a catalyst which acts as a catalyst for the reaction (crosslinking reaction) of the (meth)acrylic polymer and the isocyanate crosslinking agent, and examples thereof include an amine compound such as a tertiary amine and an organic tin. Compound An organometallic compound such as an organic lead compound, an organic zinc compound or an organic iron compound.

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 retarder added is not particularly limited, and is relative to (meth) propyl. 100 parts by weight of the olefinic polymer is usually added in an amount of about 1.0 to 5.0 parts by weight.

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

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. 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 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, but is preferably a thickness of 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 is preferably a micro-adhesive having a light adhesiveness with a peel strength of about 0.05 to 0.5 N/25 mm on the surface of the adherend. Floor. By forming 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. 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 binder, 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 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 performing a release treatment on a film obtained by laminating a plurality of polyester film layers using a binder.

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, it may be a method in which the adhesive layer 2 is applied onto the base film 1 and dried to adhere the release film 3 The method is a method in which the adhesive layer 2 is applied onto the release film 3, and the substrate film 1 is bonded and dried.

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

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 Meyer bar coating method, or an air knife coating method, and the release agent is dried by heating or ultraviolet irradiation or the like. It can be cured. 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.

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

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 polyoxyalkylene film 0.1 μm, and the coating was an addition reaction type. Polyoxane (manufactured by Toray Dow Corning, product name: SRX-211 was added to 100 parts by weight of platinum catalyst SRX-212 (1 part by weight) and 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.

Further, the adhesive layer is formed using a binder composition which is an acrylic polymer having a solid content of 40% obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate. A binder composition obtained by adding 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, and mixing them, in an amount of 100 parts by weight . 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. The reaction rate K of the adhesive layer after 15 minutes from the start of drying of the adhesive layer of this sample was 92%.

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

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

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

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

(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. The reaction rate K of the adhesive layer after 15 minutes from the start of drying of the adhesive layer of this sample was 56%.

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

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 2. The reaction rate K of the adhesive layer after 15 minutes from the start of drying of the adhesive layer of this sample was 90%.

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

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

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 reaction rate K)

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

In the same manner, the peak intensity at the time of uncaturation is determined as follows: a cross-linking catalyst is not added to the binder, and after drying in a hot air circulating oven at 80 ° C, the sample is quickly measured (for example, within 1 minute). peak intensity adhesive layer 2270cm ^-1 / 1730cm ^-1, and the peak intensity as uncured ratio (b). The reaction rate K was determined by the following formula.

Reaction rate K (%) = (1-a / b) × 100

(Here, a is an adhesive layer of a sample using Fourier transform infrared spectrophotometry absorbance peak intensity ratio obtained 2270cm ^-1 / 1730cm ^-1, b is an adhesive layer at the time of conversion uncured through Fourier transform infrared absorption spectrophotometry the resulting peak intensity ratio 2270cm ^-1 / 1730cm ^-1) of

(Measurement of storage modulus)

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

(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. 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.

(The surface of the transparent conductive film is bonded to the hard coating PET film Method for confirming the handling property when the film is protected)

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 (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. Will be hard coated outside the PET film The sample which was smooth was evaluated as (○), the sample which produced the uneven deformation of the uneven shape was evaluated as (Δ), and the sample which produced the strong deformation of the uneven shape 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, and "polymer B" is the acrylic polymer 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 examples 1 to 3, the reaction rate K of the adhesive layer after the start of drying of the adhesive layer used for the surface protective film for a transparent conductive film was 82 to 92%, and the change in the adhesive force before and after the heating process was changed. It is small, and the unevenness of the surface of the adhesive layer is very small (small). The appearance of the hard coated PET film using this surface protective film is good it is good. In addition, the handleability when the surface protective film for transparent conductive films of Examples 1-3 was bonded to the hard-coating PET film was also excellent.

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

On the other hand, in Comparative Example 1, the reaction rate K of the adhesive layer after 15 minutes from the start of drying of the adhesive layer used for the surface protective film for a transparent conductive film was as low as 56%. As a result, the surface protective film for a transparent conductive film of Comparative Example 1 has irregularities on the surface of the adhesive layer, and when the laminated product obtained by bonding the hard-coated PET film is heat-treated, the adhesive layer is The uneven shape of the surface was transferred onto the hard-coated PET film, and the appearance of the hard-coated PET film was lowered.

Further, in Comparative Example 2, the storage modulus of the adhesive layer was as low as less than 4.0 × 10 ⁵ Pa, and the reaction rate K of the adhesive layer after 15 minutes from the start of drying of the adhesive layer showed a value of up to 90%. However, the surface protective film for a transparent conductive film of Comparative Example 2 has irregularities on the surface of the adhesive layer, and when the laminate bonded to the hard coating-treated PET film is heat-treated, the adhesive layer is The uneven shape of the surface was transferred onto the hard-coated PET film, and the appearance of the hard-coated PET film was lowered. Also, in Comparative Example 3, the storage modulus of the adhesive layer down to less than 4.0 × 10 ⁵ Pa, and the dried adhesive layer is an adhesive layer of the reaction was started after 15 minutes was 74% K. However, the surface protective film for a transparent conductive film of Comparative Example 3 has irregularities on the surface of the adhesive layer, and when the laminate which is bonded to the hard coating-treated PET film is subjected to heat treatment, the adhesive layer is The uneven shape of the surface was transferred onto the hard-coated PET film, and the appearance of the hard-coated PET film was lowered.

[Industrial use possibilities]

The surface protective film for a transparent conductive film of the present invention has a very small curl in a manufacturing process of a transparent electrode for a touch panel even after being subjected to a heating process in a state of being bonded to a thin transparent conductive film. . Thereby, the operability 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 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 a transparent conductive film has a binder The adhesive layer is obtained by laminating an acrylic adhesive containing an isocyanate crosslinking agent and a crosslinking catalyst on one side of the substrate film, and the storage modulus of the adhesive layer at 30 ° C is 4.0. ×10 ⁵ Pa or more, and the adhesive layer has a reaction rate K of 75% or more after 15 minutes from the start of drying of the adhesive layer represented by the following formula, and the reaction rate K (%) = (1-a/b) × 100 wherein, for a dried adhesive layer is 2270 cm ^-1 beginning transform infrared absorption spectrophotometry of the adhesive layer obtained after 15 minutes through the Fourier / ^1730cm-1 peak intensity ratio, b is the time of the uncured adhesive layer than through Fourier transform infrared spectrophotometry absorbance peak intensity obtained 2270cm ^-1 / 1730cm ^-1 of. 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.