CN106189893B - Surface protection film for transparent conductive film and transparent conductive film using same - Google Patents
Surface protection film for transparent conductive film and transparent conductive film using same Download PDFInfo
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- CN106189893B CN106189893B CN201510349780.5A CN201510349780A CN106189893B CN 106189893 B CN106189893 B CN 106189893B CN 201510349780 A CN201510349780 A CN 201510349780A CN 106189893 B CN106189893 B CN 106189893B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
- C09J7/38—Pressure-sensitive adhesives [PSA]
- C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C09J7/385—Acrylic polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
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Abstract
The invention provides a surface protection film for a transparent conductive film, and a transparent conductive film using the same, wherein an adhesive layer of the surface protection film for the transparent conductive film maintains surface smoothness, has excellent handling performance even if the surface protection film is adhered to the transparent conductive film, improves appearance defect caused by the surface protection film in the manufacturing and processing processes of the transparent conductive film, and has good productivity in the manufacturing process of a transparent electrode for a touch panel, a surface protection film 5 for the transparent conductive film is adhered to one surface of a resin film with the transparent conductive film formed on the other surface, an adhesive layer 2 laminated on one surface of a base material film 1 is formed by using an adhesive containing an acrylic resin composition, a cross-linking agent and a cross-linking catalyst, and the storage modulus a of the adhesive layer after 5 days of aging at 40 ℃ at 30 ℃ is 4.0 × 105Pa or more, and a satisfies a relation of 0.9. ltoreq. a/b. ltoreq.1.3 between storage modulus b and a at 30 ℃ of the adhesive layer 15 minutes after the start of drying.
Description
Technical Field
The present invention relates to a surface protective film for a transparent conductive film, which is used by being 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, in which an adhesive layer is formed to maintain surface smoothness, which has excellent handleability even when the surface protective film is bonded to a transparent conductive film, which has improved appearance defects due to the surface protective film in the production and processing processes of the transparent conductive film, and which has good productivity in the production process of a transparent electrode for a touch panel, and a transparent conductive film using the surface protective film.
Background
Conventionally, 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, transparent conductive films (hereinafter, also simply referred to as "conductive films") have been widely used for the formation of transparent electrodes and the like. The transparent conductive film is formed on one surface of a base material, and is formed of, for example, ITO (indium tin oxide compound), AZO, GZO (compound in which aluminum or gallium is added to ZnO (zinc oxide)), or the like.
In the process for manufacturing the transparent electrode for a touch panel, various heating steps and reagent treatment steps are performed, for example, a crystallization step of a metal oxide film, a printing step of a resist, an etching step, a step of forming a wiring circuit using silver paste, a printing step of an insulating layer, a punching step, and the like, by annealing a transparent conductive film on which a transparent conductive film made of ITO, AZO, GZO, or the like is formed. In the process for producing such a transparent electrode, a surface protective film for a transparent conductive film is used by being bonded to the transparent conductive film in order to prevent the occurrence of stain or damage on the surface of the transparent conductive film opposite to the surface on which the transparent conductive film is formed.
In the process for producing the transparent electrode, heat treatment is performed at a temperature of about 150 ℃ for annealing, formation of a wiring circuit using a silver paste, and the like, and therefore, the protective film for a transparent conductive film is required to have heat resistance.
Various protective films for transparent conductive films have been proposed for use in the production process of transparent electrodes for touch panels and the like. For example, patent document 1 proposes a surface protective film for a transparent conductive film, in which an adhesive layer is provided on one surface of a base material made of a thermoplastic resin film having a melting point of 200 ℃. It is considered that the heat resistance is better than that of a surface protective film for a transparent conductive film using a polyolefin resin such as polyethylene or polypropylene as a base material.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2003-170535
Patent document 2: japanese patent No. 4342775
Patent document 3: japanese laid-open patent publication No. 11-268168
Patent document 4: japanese patent laid-open publication No. 2013-226676
Disclosure of Invention
Problems to be solved by the invention
The present invention provides a surface protective film for a transparent conductive film, which has an adhesive layer of the surface protective film maintaining surface smoothness and improved appearance defect defects, as in patent document 4. The surface protection film of patent document 4 is characterized by using a release film having a stiffness of 0.30mN to 40mN at 40 ℃, but the film having this stiffness has a problem of increasing thickness and cost. In addition, when manufacturing the surface protective film or when the user uses the surface protective film, the roll-up diameter of the surface protective film may be limited depending on the specifications of the processing machine used. In this case, the surface protective film using a release film having a large substrate thickness has the following problems as compared with the surface protective film using a release film having a small substrate thickness: the roll length when the transparent electrode is rolled up at a predetermined roll diameter (the roll き has a diameter of り) is shortened, and the productivity in the process of manufacturing the transparent electrode for a touch panel is lowered.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a surface protective film for a transparent conductive film, which maintains surface smoothness of an adhesive layer of the surface protective film for a transparent conductive film in a state of being unwound from a roll body (ロール body), has excellent handling properties even when it is bonded to the transparent conductive film, improves defects in appearance caused by the surface protective film for a transparent conductive film in a manufacturing process and a processing process of the transparent conductive film, and has good productivity in a manufacturing process of a transparent electrode for a touch panel, and a transparent conductive film using the surface protective film.
Means for solving the problems
The surface protective film for a transparent conductive film is produced by the following method: the adhesive is applied to a base film or a release film, a solvent in the adhesive is evaporated in a drying step, and then the release film or the base film is attached and wound into a roll shape. The present inventors have conducted extensive studies and, as a result, have found that the cured state of the adhesive layer 15 minutes after the start of drying is related to uneven deformation of the surface of the adhesive layer. Further, the present inventors have found that the use of an adhesive in which the adhesive layer is cured within 15 minutes after the start of drying can suppress the occurrence of uneven deformation on the surface of the adhesive layer to be bonded to an adherend even when a release film having a small substrate thickness is used for bonding the adhesive layer of a surface protective film for a transparent conductive film, and have completed the present invention.
In the process for producing a surface protective film, generally, an adhesive is applied to a base film and dried to form an adhesive layer, and then curing is performed in a roll state, but during this curing period, deformation of the release film occurs due to the influence of the winding-up of the roll (roll き り) and the like. Therefore, when the adhesive layer is cured after the deformation of the release film, the surface shape of the release film is transferred to the surface of the adhesive layer, and this causes a significant deterioration in the appearance of the transparent conductive film when the transparent conductive film is subjected to the manufacturing and processing processes.
The technical concept of the invention is as follows: the adhesive layer is cured before the release film is deformed while maintaining the surface protective film for the transparent conductive film in a roll form, whereby even if the release film is deformed, the deformation of the surface of the adhesive layer is suppressed, and smoothness is maintained.
That is, while maintaining the surface protective film for a transparent conductive film according to the present invention in a roll form, the adhesive layer to which the release film is bonded is cured before the adhesive layer is deformed by being pulled by the deformation of the release film, thereby preventing the occurrence of irregularities on the surface of the adhesive layer bonded to the adherend and maintaining smoothness.
The present inventors have found that the progress of curing of the adhesive layer can be grasped by comparing the storage modulus of the adhesive layer 15 minutes after the start of drying the adhesive layer and after the completion of aging (curing). More specifically, if the ratio of the storage modulus of the adhesive layer after 15 minutes from the start of drying to that after aging (curing) (a value obtained by dividing the storage modulus after aging by the storage modulus after 15 minutes from the start of drying) is within a predetermined range, even when a release film having a small substrate thickness is used for the application of the adhesive layer of the surface protective film for a transparent conductive film, the deformation of the adhesive layer to be bonded to the adherend can be suppressed.
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 by being bonded to the other surface of a resin film having a transparent conductive film formed on one surface thereof,
the surface protective film for a transparent conductive film is formed by laminating an adhesive layer on one surface of a base film, wherein the adhesive layer is formed by using an adhesive containing an acrylic resin composition, a crosslinking agent and a crosslinking catalyst, and the adhesive layer after aging for 5 days at 40 ℃ has a storage modulus at 30 ℃ of 4.0 × 105Pa or more, and the storage modulus at 30 ℃ of the adhesive layer after 15 minutes of starting drying the adhesive layer and the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days satisfy the following formula (1).
A/b is more than or equal to 0.9 and less than or equal to 1.3 formula (1)
(where a is the storage modulus of the adhesive layer at 30 ℃ after aging at 40 ℃ for 5 days, and b is the storage modulus of the adhesive layer at 30 ℃ after drying the adhesive layer for 15 minutes)
The present invention also provides a transparent conductive film obtained by bonding the surface protective film for a transparent conductive film to the other surface of a resin film having a transparent conductive film formed on one surface thereof.
ADVANTAGEOUS EFFECTS OF INVENTION
The surface protective film for a transparent conductive film of the present invention maintains surface smoothness of a formed adhesive layer in a state of being unwound from a roll body, has excellent handling properties even when being bonded to the transparent conductive film, improves defective appearance due to the surface protective film in processes of manufacturing and processing the transparent conductive film, and has good productivity in a process of manufacturing a transparent electrode for a touch panel.
In recent years, as the casing of a high-function portable terminal such as a smartphone is made thinner, the thickness of the transparent conductive film used is made thinner. The surface protective film for a transparent conductive film according to the present invention generates very little curling even after a heating step in a state of being bonded to a thinned transparent conductive film in a process for manufacturing a transparent electrode for a touch panel. This can significantly improve the workability ( property) and the production efficiency of the process for producing the transparent electrode for a touch panel.
Drawings
Fig. 1 is a cross-sectional view showing an example of a surface protective film for a transparent conductive film of the present invention.
Fig. 2 is a cross-sectional view showing an example in which the transparent conductive film of the present invention is bonded to a transparent conductive film with a surface protective film.
Fig. 3 is a schematic view showing an example of the method for producing a surface protective film for a transparent conductive film according to the present invention.
Detailed Description
The present invention will be described in detail below 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 is formed by laminating an adhesive layer 2 on one surface of a transparent flexible base film 1. A release film 3 subjected to a release treatment for protecting the surface of the adhesive layer is laminated on the surface of the adhesive layer 2 to be bonded to an adherend via its surface subjected to a release treatment.
As the base film 1, a transparent flexible plastic film is used. As a result, the appearance of the transparent conductive film of the present invention can be directly inspected in a state where the transparent conductive film is bonded to the other surface of the transparent conductive film having the transparent conductive film formed on one surface of the base material by the surface protection film. Examples of the plastic film used as the base film 1 include polyester films such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate. In addition to the polyester film, other types of plastic films may be used as long as they have a desired strength and optical suitability. The base film 1 is not particularly limited, and may be an unstretched film, a uniaxially or biaxially stretched film, or the like, but preferably has a low heat shrinkage rate.
The thickness of the base film 1 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited, and may be selected according to the transparent conductive film to be used. When the transparent conductive film to be used has a thickness of 100 μm or more, the handling property of the transparent conductive film itself is not so poor, and therefore the surface protective film is mainly focused on protecting the surface of the transparent conductive film. Therefore, a surface protective film having a thickness of about 25 to 75 μm can be used as the base film 1.
On the other hand, when the transparent conductive film to be used is as thin as 50 μm or less, the handling property of the transparent conductive film itself is poor, and therefore, considering the handling property of the surface protective film, it is preferable to use a transparent conductive film having a large thickness of the base film. The thickness of the substrate film is preferably about 100 to 188 μm.
If necessary, an anti-fouling layer for the purpose of preventing surface fouling, an antistatic layer, an oligomer-preventing layer, a hard coat layer for preventing scratches, or an adhesion-facilitating treatment such as corona discharge treatment or anchor coating (アンカーコート) treatment may be laminated on the surface of the base material film 1 opposite to the surface on which the adhesive layer 2 is laminated.
The adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention is preferably an acrylic adhesive. Particularly preferred is a two-pack type adhesive prepared (blended) with an acrylic adhesive and a crosslinking agent immediately before use.
As the acrylic adhesive, an adhesive in which a crosslinking agent and, if necessary, an adhesion-imparting agent are added to a (meth) acrylic polymer (acrylic resin composition) is preferable. The (meth) acrylic polymer is usually a polymer obtained by copolymerizing a main monomer such as N-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, and the like, with a comonomer such as acrylonitrile, vinyl acetate, methyl methacrylate, ethyl acrylate, and the like, and a functional monomer such as acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylolmethacrylamide, and the like. The monomer composition constituting the (meth) acrylic polymer is preferably 50% or more of the (meth) acrylic monomer, and the (meth) acrylic monomer may be 100%.
Examples of the crosslinking agent include isocyanate compounds, epoxy compounds, melamine compounds, metal chelate compounds, and the like, and among them, isocyanate compounds are preferable. Further preferred are polyisocyanate compounds having at least 2 or 3 or more isocyanate (NCO) groups in one molecule.
The polyisocyanate compound is classified into aliphatic isocyanate, aromatic isocyanate, acyclic isocyanate, alicyclic isocyanate, and the like, and may be any one. Specific examples of the difunctional isocyanate compound include aliphatic isocyanate compounds such as Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI); aromatic isocyanate compounds such as diphenylmethane diisocyanate (MDI), Xylylene Diisocyanate (XDI), hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenyldiisocyanate (TOID), and Tolylene Diisocyanate (TDI).
Examples of the trifunctional or higher isocyanate compound include a biuret-type modified product and an isocyanurate-type modified product of diisocyanates (compounds having 2 NCO groups in one molecule); and adducts (polyol modified products) of a trivalent or higher polyhydric alcohol (a compound having at least 3 OH groups in one molecule) such as Trimethylolpropane (TMP) and glycerin.
The amount of the crosslinking agent to be added is not particularly limited, and may be determined in consideration of the kind, polymerization degree, functional group amount, etc. of the (meth) acrylic polymer, and is usually about 0.5 to 10 parts by weight relative to 100 parts by weight of the (meth) acrylic polymer.
In addition, since the adhesive layer needs to be cured before the release film is deformed during the maintenance in a roll form of the surface protective film for a transparent conductive film according to the present invention, it is preferable to add a crosslinking catalyst in order to promote the crosslinking reaction between the (meth) acrylic polymer and the crosslinking agent. The crosslinking catalyst may be any one that functions as a catalyst for the reaction (crosslinking reaction) between the (meth) acrylic polymer and the crosslinking agent, and when a polyisocyanate compound is used as the crosslinking agent, there may be mentioned amine compounds such as tertiary amines, organic tin compounds, organic lead compounds, organic zinc compounds, organic iron compounds and other organic metal compounds.
Examples of the tertiary amine include trialkylamines, N' -tetraalkyldiamines, N-dialkylaminols, triethylenediamine, morpholine derivatives, and piperazine derivatives.
Examples of the organotin compound include dialkyltin oxide, fatty acid salts of dialkyltin, fatty acid salts of stannous, and the like.
The amount of the crosslinking catalyst to be added is not particularly limited, and may be determined in consideration of the type, polymerization degree, functional group amount, type, amount and the like of the (meth) acrylic polymer, and is usually about 0.01 to 0.5 parts by weight relative to 100 parts by weight of the acrylic polymer.
In addition, a crosslinking retarder may be contained as necessary in order to suppress excessive viscosity increase and gelation of the adhesive composition after the preparation of the crosslinking agent and to prolong the pot life of the adhesive composition.
The crosslinking retarder is β -ketoester such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, β -diketone such as acetylacetone, 2, 4-hexanedione, benzoylacetone, etc., particularly preferably at least one member selected from the group consisting of acetylacetone and ethyl acetoacetate.
The amount of the crosslinking retarder added is not particularly limited, and is usually about 1.0 to 5.0 parts by weight per 100 parts by weight of the (meth) acrylic polymer.
Further, an adhesion promoter may be added to the adhesive as needed. Examples of the tackifier include rosin-based, coumarone-based, terpene-based, petroleum-based, and phenol-based ones.
The adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention may be mixed with an antistatic agent as needed. As the antistatic agent, an antistatic agent having good dispersibility in the (meth) acrylic polymer or compatibility with the (meth) acrylic polymer is preferable. Examples of the antistatic agent that can be used include surfactant systems, ionic liquids, alkali metal salts, metal oxides, metal fine particles, conductive polymers, carbon nanotubes, and the like. From the viewpoint of transparency, affinity with the (meth) acrylic polymer, and the like, a surfactant system, an ionic liquid, an alkali metal salt, and the like are preferable. The amount of the antistatic agent added to the adhesive can be appropriately determined in consideration of the kind of the antistatic agent and the compatibility with the base polymer. The type and amount of the antistatic agent are specifically set in consideration of the required peeling static voltage, staining property of an adherend, adhesive strength, and the like when the surface protective film for a transparent conductive film according to the present invention is peeled from the transparent conductive film.
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, for example, preferably about 5 to 50 μm, and more preferably about 5 to 30 μm. When the thickness of the adhesive layer 2 exceeds 50 μm, the cost for producing the surface protective film for a transparent conductive film increases, and thus competitiveness is impaired. When the thickness of the adhesive layer 2 is less than 5 μm, there are problems as follows: when the adhesion to the transparent conductive film is reduced or foreign matter is mixed in when the surface protective film is bonded to the transparent conductive film, the transparent conductive film is largely deformed.
The adhesive layer 2 of the surface protective film for a transparent conductive film according to the present invention is preferably a micro adhesive layer having a slight adhesiveness with a peel strength of about 0.05 to 0.5N/25mm from the surface of an adherend. By forming the surface protective film for a transparent conductive film having such a micro adhesive layer, excellent workability can be obtained in which the film can be easily peeled from an adherend.
The material of the release film 3 of the surface protective film for a transparent conductive film according to the present invention is not particularly limited. Examples of the material of the release film that can be used include a polyolefin film such as a polyethylene film, a polypropylene film, and a polymethylpentene film, a release film obtained by applying a release treatment using a release agent such as a silicone-based release agent to the surface of a film such as a polyester film, a fluororesin film, and a polyimide film. Further, the adhesive may be a film obtained by laminating 2 or more films using an adhesive, or a laminated film obtained by melt-extruding a resin on a film and laminating the film. A release film is obtained by performing a release treatment on the single-layer film or the laminated film using a release agent such as a silicone release agent.
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. In general, the thickness of the release film is usually about 19 μm to 75 μm.
When the release film 3 is made thick, the entire length of the surface protective film for a transparent conductive film is shortened and the manufacturing cost is increased in a roll wound in a roll shape having the same winding diameter, and therefore, the release film 3 is made to have an appropriate thickness. The release film 3 is preferably a release film obtained by subjecting a single-layer polyester film to a release treatment, or a release film obtained by subjecting a film obtained by laminating a plurality of polyester films to a release treatment using an adhesive.
The method for laminating the adhesive layer 2 and the release film 3 in this order on the base film 1 may be carried out by a known method, and is not particularly limited. Specifically, the method may be any of a method of applying the adhesive layer 2 on the base film 1, drying the adhesive layer, and then bonding the release film 3, a method of applying the adhesive layer 2 on the release film 3, drying the adhesive layer, and then bonding the base film 1, and the like.
The adhesive layer can be formed on the base film 1 by a known method. Specifically, a known coating method such as a reverse coating method, a comma coating method, a gravure printing method, a slot die coating method, a meyer rod coating method, or an air knife coating method can be used.
The method of applying the peeling treatment to the peeling film 3 may be performed by a known method. Specifically, the release agent may be 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 then dried and cured by heating, ultraviolet irradiation, or the like. If necessary, the film to be subjected to the peeling treatment may be subjected to pretreatment for improving the adhesion of the peeling agent to the film, such as corona treatment, plasma treatment, anchor coating, or the like.
Fig. 2 is a schematic configuration diagram showing an example of a laminated film 11 in which a surface protective film for a transparent conductive film of the present invention is bonded to a transparent conductive film.
The laminated film 11 is a laminated film in which an adhesive film 4 is bonded to the surface of a transparent conductive film 10 with the adhesive layer 2 thereof, and the adhesive film 4 is obtained by peeling a release film 3 from a surface protection film 5 for a transparent conductive film of the present invention. The transparent conductive film 10 has a transparent conductive film 7 formed on one surface 6a of a resin film 6. The adhesive film 4 is bonded to the other surface 6b of the resin film 6.
Examples of the transparent conductive film 10 include a polyethylene terephthalate (PET) film on which a transparent conductive film such as ITO, AZO, or GZO is formed, and a cyclic polyolefin film on which a transparent conductive film such as ITO, AZO, or GZO is formed. Such transparent conductive films are widely used for forming transparent electrodes and the like 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.
The surface protective film for a transparent conductive film of the present invention exhibits the following excellent effects: in the manufacturing process of the transparent electrode of the touch panel and the like, the workability and the production efficiency can be greatly improved, and even if the transparent conductive film is thinned, the workability and the handling performance are not reduced.
Fig. 3 is a schematic view showing an example of the method for producing a surface protective film for a transparent conductive film according to the present invention.
The release film 3 and the base film 1 are continuously discharged from a roll 21 wound with the release film 3 subjected to the release treatment and a roll 22 wound with the base film 1, respectively. An adhesive is applied to one surface of the base film 1 by an adhesive application device 23. The adhesive-coated base film 1 is dried in a drying furnace 24 to form an adhesive film 4. The surface of the adhesive film 4 on which the adhesive layer is formed and the surface of the release film 3 subjected to the release treatment are opposed to each other and pressure-bonded by pressure- bonding rollers 25 and 26, thereby obtaining a surface protection film 5 for a transparent conductive film. The transparent conductive film is rolled up as a roll 27 with the surface protective film 5. Normally, the transparent conductive film is stored and transported in the state of a roll 27 with the surface protection film 5. When the transparent conductive film is bonded to the transparent conductive film 10, the surface protection film 5 for the transparent conductive film is unwound from the roll 27.
[ examples ]
The present invention will be further described below based on examples.
(preparation of surface protective film for transparent conductive film of example 1)
A biaxially oriented polyester film having a thickness of 25 μm was coated on one surface thereof with a paint obtained by diluting an addition reaction type silicone (product name: SRX-211100 parts by weight manufactured by Toray Dow Corning, to which a platinum catalyst SRX-2121 parts by weight was added) with a toluene/ethyl acetate 1:1 mixed solvent by a Meyer rod method so that the thickness of the silicone film after drying became 0.1 μm. Further, the film was dried and cured in a hot air circulating oven at a temperature of 120 ℃ for 1 minute to obtain a release film of example 1.
The adhesive layer was formed using an adhesive composition obtained by adding 4 parts by weight of an HDI crosslinking agent (product name: CORONETHX manufactured by NIPPON POLYURETHANE INDUSTRIAL CO., LTD.) and 0.03 part by weight of dibutyltin dilaurate as a crosslinking catalyst to 100 parts by weight of an acrylic polymer having a solid content of 40% obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate, and mixing them. The adhesive composition was applied to a polyethylene terephthalate film having a thickness of 125 μm so that the thickness of the adhesive layer after drying was 20 μm, and the adhesive was dried in a hot air circulating oven at a temperature of 130 ℃ for 1 minute. Then, the silicone treated surface of the release film of example 1 prepared as described above was laminated on the surface of the adhesive layer to obtain a surface protective film for a transparent conductive film of example 1.
(preparation 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 changed to 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 set to 120 ℃.
(preparation of surface protective film for transparent conductive film of comparative example 1)
A surface protection film for a 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.
(preparation 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 set to 100 ℃.
(preparation 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 example 1 except that an adhesive composition obtained by adding and mixing 1 part by weight of HDI-based crosslinking agent (product name: CORONETHX, manufactured by NIPPON POLYURETHANE INDUSTRIAL CO., LTD.) and 0.03 part by weight of dibutyltin dilaurate as a crosslinking catalyst to 100 parts by weight of an acrylic polymer having a solid content of 40% obtained by copolymerizing 2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate was used as the adhesive composition.
(preparation of surface protective film for transparent conductive film of comparative example 4)
A surface protective film for a transparent conductive film of comparative example 4 was obtained in the same manner as in example 1, except that an adhesive composition obtained by adding 4 parts by weight of an epoxy-based crosslinking agent (trade name: TETRAD-C, manufactured by Mitsubishi gas chemical corporation) 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 was used as the adhesive composition.
The method of the evaluation test and the test results are shown below. Here, a "hard coat treated PET film" is used as an example of the substrate (film) for the transparent conductive film.
(measurement of storage modulus)
The samples obtained in examples and comparative examples were measured for storage modulus (b) at 30 ℃ of the adhesive layer 15 minutes after the start of drying and storage modulus (a) at 30 ℃ of the adhesive layer after curing at 40 ℃ for 5 days, using a viscoelasticity measuring apparatus (manufactured by ABM corporation, Reogel-E4000).
In table 1 below, the storage modulus (b) is abbreviated as "storage modulus before curing (b)", the storage modulus (a) is abbreviated as "storage modulus after curing (a)", and the ratio (a/b) between them is abbreviated as "ratio after curing/before curing (a/b)".
(measurement of initial adhesion of surface protective film for transparent conductive film)
A PET film (manufactured by KIMOTO, Inc.; brand: KB film #50G01) which had been subjected to a hard coating treatment on one surface of a biaxially oriented polyester film having a thickness of 50 μm and was also used for the hard coating treatment of an ITO film was used. A transparent conductive film cut to a width of 25mm was bonded to the surface of the PET film subjected to the hard coat treatment with a surface protective film, and then stored at 23 ℃ and 50% RH for 1 hour to prepare a sample for measuring an initial adhesive force. Then, the strength when the surface protective film for the transparent conductive film was peeled in the 180 ° direction at a peeling speed of 300 mm/min was measured by using a tensile tester, and this was used as the initial adhesion (N/25 mm).
A small bench test apparatus EZ-L manufactured by Shimadzu corporation was used as the measuring apparatus.
< measurement of adhesion force after heating of surface protective film for transparent conductive film >
A transparent conductive film cut to a width of 25mm was bonded to the hard-coated surface of the PET film with a surface protective film, and then stored at 150 ℃ for 1 hour to obtain a sample for measuring the adhesion after heating, and the measurement was carried out in the same manner as the measurement of the initial adhesion to obtain the adhesion after heating (N/25 mm).
A small bench test apparatus EZ-L manufactured by Shimadzu corporation was used as the measuring apparatus.
(method of confirming handling Property when surface protective film for transparent conductive film was laminated on hard coat treated PET film)
A sample obtained by subjecting a transparent conductive film surface protective film to an appearance inspection was used as the following transparent conductive film surface protective film, the transparent conductive film surface protective film was bonded to a hard coat treated surface of a hard coat treated PET film (manufactured by KIMOTO, Inc., brand name: KB film #50G01), and the laminate was cut into A4 size, 1 of 4 corners of the cut sample was held, and the film was oscillated back and forth 20 times in the air using the film surface, and then the presence or absence of bending and deformation of the hard coat treated PET film was visually confirmed, and the sample having no bending and deformation of the hard coat treated PET film was evaluated as (○) and the sample having bending and deformation was evaluated as (×).
(method of inspecting appearance of surface protective film for transparent conductive film)
A roll product of the surface protective film for a transparent conductive film (roll length: × 100m having a width of 400 mm) was produced using a test coater, and the roll product was heated in an oven at 40 ℃ for 5 days to cure the adhesive, and then the appearance of the sample of the surface protective film for a transparent conductive film unwound from the roll product at a position 50m from the end (a position approximately equidistant from both ends) was visually observed, and the sample having a smooth surface of the adhesive layer was evaluated as (○), the sample having weak unevenness formed on the surface of the adhesive layer was evaluated as (△), and the sample having strong unevenness formed on the surface of the adhesive layer was evaluated as (×).
(method of inspecting appearance of hard coating film)
A sample in which an appearance inspection was performed on a surface protective film for a transparent conductive film was used as the surface protective film for a transparent conductive film, the surface protective film for a transparent conductive film was attached to a hard coat treated surface of a hard coat treated PET film (manufactured by KIMOTO, Inc., brand name: KB film #50G01), and then, a heating treatment was performed at 150 ℃ for 1 hour, the surface state of the hard coat treated PET film was visually observed after peeling the surface protective film for a transparent conductive film, the sample in which the appearance of the hard coat treated PET film was smooth was evaluated as (○), the sample in which uneven weak deformation was generated was evaluated as (△), and the sample in which uneven strong deformation was generated was evaluated as (×).
The measurement results for the respective samples are shown in table 1, wherein "polymer a" is the acrylic polymer described in example 1, "polymer B" is the acrylic polymer described in comparative example 3, "polymer C" is the acrylic polymer described in comparative example 4, "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, and the values of the storage modulus in table 1 are shown in the form of mantissas and indices before and after E, for example, 4.0 × 105Is noted as 4.0E + 05.
[ Table 1]
The following judgment was made from the measurement results shown in Table 1.
In examples 1 to 2, the ratio "(a/b) of the storage modulus at 30 ℃ of the adhesive layer used in the surface protective film for the transparent conductive film," the storage modulus at 30 ℃ of the adhesive layer after 15 minutes from the start of drying of the adhesive layer to the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days "was 1.0 to 1.2, and the change in adhesive force before and after the heating step was small and the unevenness on the surface of the adhesive layer was very small (small). The hard-coated PET film using the surface protective film had good appearance. In addition, the transparent conductive film of examples 1 to 2 was bonded to the hard coat treated PET film with a surface protective film, and the handling property was also very good.
In example 3, although the irregularities on the surface of the adhesive layer were slightly larger than those in examples 1 to 2, the irregularities on the surface of the adhesive layer were 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 in which no crosslinking catalyst was added, the ratio "(a/b) of the storage modulus at 30 ℃ of the adhesive layer 15 minutes after the start of drying of the adhesive layer to the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days was 27.5, and unevenness was generated on the surface of the adhesive layer in the surface protective film for a transparent conductive film. Therefore, when a laminate product formed by laminating the hard coat treated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard coat treated PET film, and the appearance of the hard coat treated PET film is degraded.
In comparative example 2, "the ratio of the storage modulus at 30 ℃ of the adhesive layer after 15 minutes from the start of drying of the adhesive layer to the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days" (a/b) was 1.5, and irregularities were formed on the surface of the adhesive layer by the surface protective film for a transparent conductive film. Therefore, when a laminate product formed by laminating the hard coat treated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard coat treated PET film, and the appearance of the hard coat treated PET film is degraded.
In comparative example 3 using an adhesive layer having a low storage modulus, "the ratio of the storage modulus at 30 ℃ of the adhesive layer 15 minutes after the start of drying of the adhesive layer to the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days" (a/b) was 1.1, but the surface protection film for the transparent conductive film of comparative example 3 had irregularities on the surface of the adhesive layer. Therefore, when a laminate product formed by laminating the hard coat treated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard coat treated PET film, and the appearance of the hard coat treated PET film is degraded.
In comparative example 4, the ratio "(a/b) of the storage modulus at 30 ℃ of the adhesive layer 15 minutes after the start of drying of the adhesive layer to the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days was 10.0, and unevenness was generated on the surface of the adhesive layer by the surface protective film for a transparent conductive film. Therefore, when a laminate product formed by laminating the hard coat treated PET film is subjected to heat treatment, the uneven shape of the surface of the adhesive layer is transferred to the hard coat treated PET film, and the appearance of the hard coat treated PET film is degraded.
[ Industrial Applicability ]
The surface protective film for a transparent conductive film according to the present invention generates very little curling even after a heating step in a state of being bonded to a thinned transparent conductive film in a process for manufacturing a transparent electrode for a touch panel. Thus, the workability and the production efficiency of the manufacturing process of the transparent electrode for a touch panel can be greatly improved. The surface protective film for a transparent conductive film of the present invention can be widely used as a surface protective film for manufacturing and processing a transparent conductive film, which is used 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.
[ description of symbols ]
1 … base film, 2 … adhesive layer, 3 … release film, 4 … adhesive film, 5 … surface protection film for transparent conductive film, 6 … resin film, one surface of 6a … resin film, the other surface of 6b … resin film, 7 … transparent conductive film, 10 … transparent conductive film, 11 … laminated film, roll of 21 … release film, roll of 22 … base film, 23 … adhesive coating device, 24 … drying furnace, 25, 26 … pressure welding roller, and roll of 27 … surface protection film for transparent conductive film.
Claims (2)
1. A surface protective film for a transparent conductive film, which is used by being bonded to the other surface of a resin film having a transparent conductive film formed on one surface thereof,
the surface protective film for transparent conductive film is formed by laminating a base material film, an adhesive layer and a stripping film in sequence,
the adhesive layer is formed by using an adhesive composition, the adhesive composition only contains 0.5-10 parts by weight of a cross-linking agent and 0.01-0.5 part by weight of more than one cross-linking catalyst selected from the group consisting of amine compounds and organic metal compounds relative to 100 parts by weight of (meth) acrylic polymers, the cross-linking agent is only isocyanate compounds,
the (meth) acrylic polymer is a copolymer obtained by copolymerizing 1 or more monomers selected from the group consisting of N-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, with 1 or more monomers selected from the group consisting of acrylonitrile, vinyl acetate, methyl methacrylate, ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, and N-methylolmethacrylamide,
the storage modulus of the adhesive layer at 30 ℃ after aging at 40 ℃ for 5 days was 4.0 × 105Pa or more, and the storage modulus at 30 ℃ of the adhesive layer after 15 minutes of drying of the adhesive layer and the storage modulus at 30 ℃ of the adhesive layer after aging for 5 days at 40 ℃ satisfy the following formula (1),
a/b is more than or equal to 0.9 and less than or equal to 1.3 formula (1)
Where a is the storage modulus at 30 ℃ of the adhesive layer after aging at 40 ℃ for 5 days, b is the storage modulus at 30 ℃ of the adhesive layer after drying the adhesive layer for 15 minutes,
the surface protective film for a transparent conductive film is produced by winding the film into a roll.
2. A transparent conductive film obtained by bonding an adhesive film obtained by peeling a release film from the 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.
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| JP2014-161801 | 2014-08-07 |
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| JP6319919B2 (en) * | 2016-12-21 | 2018-05-09 | 藤森工業株式会社 | Method for producing surface protective film for transparent conductive film |
| CN106898414B (en) * | 2017-01-20 | 2018-09-21 | 江西沃格光电股份有限公司 | Touch screen high resistance film and preparation method thereof and touch screen |
| JP6871049B2 (en) * | 2017-04-12 | 2021-05-12 | 住友化学株式会社 | Optical laminate and liquid crystal display device |
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| JP2970782B2 (en) | 1991-05-21 | 1999-11-02 | 三菱鉛筆株式会社 | Ink composition for ethanolic metallic color |
| JPH11268168A (en) | 1998-03-24 | 1999-10-05 | Kanegafuchi Chem Ind Co Ltd | Plastic film with transparent conducting film and protective film |
| JP2003170535A (en) | 2001-12-05 | 2003-06-17 | Nitto Denko Corp | Surface protecting film for transparent conducting film |
| JP2004319045A (en) * | 2003-04-18 | 2004-11-11 | Lintec Corp | Sheet for manufacturing optical disk, and optical disk |
| JP5591477B2 (en) * | 2008-03-13 | 2014-09-17 | 日東電工株式会社 | Optical member pressure-sensitive adhesive composition, optical member pressure-sensitive adhesive layer, pressure-sensitive adhesive optical member, transparent conductive laminate, touch panel, and image display device |
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| TWI627255B (en) | 2018-06-21 |
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