TW201546233A - Protective film, and protective-film-attached film on which transparent conductive film is to be laminated - Google Patents

Abstract

A protective film (1) comprising a base material (11) and an adhesive agent layer (12) laminated on one surface of the base material (11), wherein the adhesive agent layer (12) comprises an adhesive agent produced by curing an adhesive composition, the adhesive composition contains 60% by mass or more of at least one energy-ray-curable compound having a molecular weight of 500 to 10000, and the adhesion force of the protective film (1) to a non-alkali glass is 20 to 300 mN/25 mm. The protective film (1) exhibits an excellent peel property even after being heated.

Description

Protective film and film for transparent conductive film lamination with protective film

The present invention relates to a protective film for protecting a film for a transparent conductive film laminate or the like, a method for producing the same, and a film for a transparent conductive film laminate with a protective film.

In recent years, in various mobile electronic devices such as smart phones and tablet computers, the use of touch panels as displays has gradually increased. Examples of the touch panel include a resistive film method and a capacitive method. However, in the above mobile electronic device, a capacitive method is mainly used.

In the touch panel, a transparent conductive film made of a patterned tin-doped indium oxide (ITO) or the like is laminated on a film for a transparent conductive film layer mainly composed of a transparent plastic substrate. film. Further, as an example, a hard coat layer is provided on one side of the uncoated transparent conductive film in the transparent plastic substrate.

In order to protect the surface on one side of the uncoated transparent conductive film in the above-mentioned film for transparent electroconductive film lamination (or transparent conductive film), and in order to improve operability, it is proposed to attach a protective film on the surface (Patent Document 1) 2). Such a protective film includes a base film and an adhesive layer, and is attached to the film for a transparent conductive film laminate via the adhesive layer.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-154593

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-170535

Here, on the surface of the film for transparent conductive film lamination (film for transparent conductive film lamination with protective film) to which the protective film is attached, the surface on one side of the protective film is not attached, by vacuum evaporation The transparent conductive film is formed by a sputtering method, a CVD method, an ion plating method, or the like. Then, the transparent conductive film is patterned by etching treatment or the like.

However, in recent years, from the viewpoint of improving electrical conductivity, the above transparent conductive film is often subjected to heat treatment before or after the patterning process to increase the crystallinity of a material (for example, ITO) which forms a transparent conductive film.

The adhesive used in the adhesive layer of the protective film disclosed in Patent Documents 1 and 2 is a thermosetting acrylic adhesive, and when heated as described above, the adhesive force (peeling force) is remarkably increased. Therefore, when the protective film is peeled off after using the protective film, it is difficult to peel off from the transparent conductive film, and workability is lowered.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a protective film which is excellent in peelability after heating, a method for producing the same, and a transparent conductive film layer with a protective film which is excellent in peelability of the protective film after heating. film.

In order to achieve the above object, a first aspect of the present invention provides a protective film comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the adhesive layer is an adhesive formed by hardening an adhesive composition. In the above-mentioned adhesive composition, one or two or more kinds of energy ray curable compounds having a molecular weight of 500 to 10,000 are contained in an amount of 60% by mass or more, and the adhesion of the protective film to the alkali-free glass is 20 to 300 mN/25 mm. (Invention 1).

According to the invention (Invention 1), the adhesive layer is formed of an adhesive obtained by curing the adhesive composition, and the adhesive force is set within the above range, even when the transparent conductive film is crystallized, The increase in adhesion is also suppressed, and excellent peeling properties are exerted. As described above, since the protective film of the present invention is excellent in heat resistance after heating, it can also be referred to as a "heat-resistant protective film".

In the above invention (Invention 1), at least one of the energy ray-curable compounds has an oxyalkylene chain, and the amount of the alkylene oxide in the total amount of the energy ray-curable compound is preferably from 35 to 90% by mass. ).

In the above invention (Invention 2), the amount of the energy ray-curable compound having the oxyalkylene chain in the total amount of the energy ray-curable compound is preferably 40% by mass or more (Invention 3).

In the above invention (Inventions 1 to 3), it is preferred that the energy ray curable compound is a polyfunctional (meth) acrylate (Invention 4).

In the above invention (Invention 4), it is preferred that the polyfunctional (meth) acrylate is a trifunctional or higher (meth) acrylate (Invention 5).

In the above invention (Inventions 1 to 5), the above-mentioned adhesive composition It is preferred that the adhesive component having a weight average molecular weight of more than 10,000 is not contained (Invention 6).

In the above invention (Inventions 1 to 6), the protective film is attached to the surface of one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, and the transparent conductive film is laminated on the film for the transparent conductive film layer. It is preferred to be stripped at any stage (Invention 7).

In the above invention (Invention 7), when a hard coat layer is formed on one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, the protective film is preferably attached to the hard coat layer (Invention 8) ).

The present invention provides a method for producing a protective film, which is a method for producing the protective film (Inventions 1 to 8), wherein a coating liquid containing the adhesive composition is applied to one surface of the substrate. The coating layer of the adhesive composition is formed by drying, and the coating layer is irradiated with an energy ray to cure the coating layer to form an adhesive layer (Invention 9).

In the above invention (Invention 9), it is preferred to irradiate the energy ray of the coating layer in the presence of oxygen (Invention 10).

The present invention provides a film for a transparent conductive film layered with a protective film, comprising: a film for a transparent conductive film layer; and the protective film (Inventions 1 to 8) attached to the film for a transparent conductive film layer The surface of one side of the transparent conductive film is not laminated (Invention 11).

The peeling property of the protective film of the present invention is still excellent after heating. According to the method for producing a protective film of the present invention, such a protective film can be easily produced. Further, the film for a transparent conductive film laminate with a protective film of the present invention is protected. The peeling property of the protective film is excellent after heating, and exhibits excellent workability.

1‧‧‧Protective film

11‧‧‧Substrate

12‧‧‧Adhesive layer

2‧‧‧Transparent film for transparent conductive film

21‧‧‧Transparent plastic substrate

22‧‧‧hard coating

23‧‧‧Optical adjustment layer

3‧‧‧Thin film for transparent conductive film lamination with protective film

4‧‧‧Transparent conductive film

Fig. 1 is a cross-sectional view showing a protective film according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a film for a transparent conductive film laminate with a protective film according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[protective film]

The protective film 1 according to an embodiment of the present invention comprises a substrate 11 and an adhesive layer 12 laminated on one surface (upper side in the first drawing) of the substrate 11.

(1) Substrate

As the substrate 11, a heat resistance which can withstand the heating conditions when the transparent conductive film is crystallized can be used. The heating condition is usually 100 to 180 ° C, preferably about 130 to 150 ° C. Specifically, it is preferred to use a heat shrinkage ratio after heating the film 1 at 150 ° C for 1 hour into the range described later.

As such a substrate 11, for example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyimide, polyetherimide, polycarbonate, A plastic film composed of a resin such as polymethylpentene, polyphenylene sulfide or a liquid crystal polymer is preferable, and may be a film composed of a single layer or a film of a plurality of layers of the same type or different types. Among the above, polyethylene terephthalate film is particularly preferred.

In addition, in the above plastic film, in addition to the filler, it is also possible It contains additives such as heat resistance improver and ultraviolet absorber.

In order to improve the adhesion to the adhesive layer 12, the substrate 11 may be subjected to a surface treatment such as an oxidation method or a roughening method or a primer treatment as needed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone/ultraviolet irradiation treatment, and the like, and examples of the unevenness method include Sandblasting method, spray coating method, etc. These surface treatment methods can be appropriately selected depending on the type of the base film.

In consideration of heat resistance, workability, and cost, the thickness of the substrate 11 is preferably 50 to 200 μm, particularly preferably 75 to 150 μm, and more preferably 100 to 125 μm.

(2) Adhesive layer

The adhesive layer 12 is cured by one or two or more adhesive compositions (hereinafter sometimes referred to as "adhesive composition P") containing 60% by mass or more of the energy ray curable compound having a molecular weight of 500 to 10,000. Made of adhesive. The adhesive layer 12 composed of the adhesive which cures the adhesive composition P is suppressed from the heating condition when the transparent conductive film is crystallized, and the adhesive strength is suppressed, and the peeling property is excellent. Further, since the protective film 1 including the adhesive layer 12 does not need to be air-dried (during the need for maintenance), the cost advantage is also large.

The energy ray-curable compound has a molecular weight of 500 to 10,000, preferably 1,000 to 7,500, more preferably 1,500 to 5,000. When the molecular weight of the energy ray curable compound is 500 or more, a stable adhesive layer 12 can be formed. And, the molecular weight of the energy ray curable compound is 10,000 Hereinafter, the increase in the adhesive strength after heating of the obtained adhesive is suppressed.

The content of the energy ray-curable compound in the adhesive composition P is 60% by mass or more, preferably 75% by mass or more, and particularly preferably 90% by mass or more. When the content of the energy ray curable compound is 60% by mass or more, the increase in the adhesive strength after heating of the obtained adhesive is suppressed.

In consideration of the peeling property after the heating of the adhesive, the adhesive composition P does not contain an adhesive component having a weight average molecular weight of more than 10,000, and for example, an acrylic polymer which is generally used as an adhesive main component is preferably contained. When it is contained, the content is preferably 40% by mass or less in the adhesive composition P, more preferably 25% by mass or less, and still more preferably 10% by mass or less. Further, the weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

It is preferable that at least one of the energy ray-curable compounds has an oxyalkylene chain, and an oxyalkylene chain having any alkenyl group having 2 to 4 carbon atoms is more preferable, and an oxyethylene chain is particularly preferable. The oxyalkylene chain imparts adhesion to the resulting adhesive.

The amount of the alkylene oxide in the total amount of the energy ray-curable compound is preferably from 35 to 95% by mass, particularly preferably from 45 to 90% by mass, and more preferably from 55 to 85% by mass. When the amount of the alkylene oxide in the total amount of the energy ray-curable compound is 35% by mass or more, the obtained adhesive exhibits a good adhesive force, and the amount of the alkylene oxide is 95% by mass or less, whereby the adhesive can be easily adhered. The agent is hardened, and sufficient adhesion to the substrate 11 can be ensured.

Further, the amount of the energy ray-curable compound having an oxyalkylene chain in the total amount of the energy ray-curable compound is 40% by mass or more. Preferably, 60% by mass or more is particularly preferable, and 90% by mass or more is further more preferable. When the amount of the energy ray-curable compound having an oxyalkylene chain is 40% by mass or more, the obtained adhesive exerts a good adhesive force.

As the energy ray-curable compound, an acrylic monomer or an oligomer is preferably used in the range in which the adhesion of the protective film 1 is within the range described later. Specific examples thereof include polyfunctional (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate. Among them, polyfunctional (meth) acrylate is preferred. Therefore, the energy ray-curable compound having an oxyalkylene chain is preferably an alkylene oxide-modified polyfunctional (meth) acrylate. In the present specification, (meth) acrylate means both acrylate and methacrylate. Other similar terms are also the same.

From the viewpoint of curability, the polyfunctional (meth) acrylate is preferably a trifunctional or higher functional group, the tetrafunctional hexa-6 functional group is particularly preferred, and the tetrafunctional quinone-5 functional group is further preferred.

Examples of the polyfunctional (meth) acrylate include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butanediol di(meth)acrylate, and neopentyl glycol. (Meth) acrylate, hexanediol di(meth) acrylate, trimethylolethane tri(meth) acrylate, trimethylolpropane tri(meth) acrylate, pentaerythritol tris (methyl) ) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris (meth) acrylate, triallyl (methyl) Acrylate and the like. Among the above, pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate are preferred, and pentaerythritol tetraacrylate and dipentaerythritol hexaacrylate are particularly preferred. Therefore, as the polyfunctional (meth) acrylate having an oxyalkylene chain, an oxyalkylene-modified pentaerythritol tetraacrylate and an alkylene oxide-modified dipentaerythritol hexaacrylate are particularly preferable. According to these, the obtained adhesive is particularly excellent in peelability after heating.

The above polyfunctional (meth) acrylate may be used alone or in combination of two or more. As the polyfunctional (meth) acrylate, only the alkylene oxide (especially ethylene)-modified pentaerythritol tetraacrylate and/or alkylene oxide (especially ethylene)-modified dipentaerythritol hexaacrylate, or a combination of alkylene oxides (especially It is more preferred to modify the pentaerythritol tetraacrylate and/or alkylene oxide (especially ethylene)-modified dipentaerythritol hexaacrylate and the non-oxyalkylene-modified pentaerythritol tetraacrylate and/or dipentaerythritol hexaacrylate.

When ultraviolet rays are used as the active energy ray for curing the adhesive composition P, it is preferred that the adhesive composition P contains a photopolymerization initiator. By containing a photopolymerization initiator, the energy ray curable compound can be effectively cured, and the hardening time and the amount of irradiation of the active energy ray can be reduced.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropyl-1-one, 1 -hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)benzene 2-(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2- Methyl hydrazine, 2-ethyl hydrazine, 2-tert-butyl hydrazine, 2-amino hydrazine, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chlorothioxanthone, 2 , 4-dimethyl Thiophenone, 2,4-diethylthioxanthone, benzoin dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy- 2-methyl-1[4-(1-methylvinyl)phenyl]acetone], 2,4,6-trimethylbenzylidene-diphenyl-phosphine oxide, and the like. These may be used alone or in combination of two or more.

The photopolymerization initiator is used in an amount ranging from 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the energy ray-curable compound, and is preferably used in an amount of from 1 to 10 parts by mass.

The adhesive composition P may contain various additives such as an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, and the like as needed.

The thickness of the adhesive layer 12 is preferably 5 to 100 μm, particularly preferably 10 to 75 μm, and further preferably 15 to 50 μm. When the thickness of the adhesive layer 12 is within the above range, good adhesion and peeling force can be exhibited.

(3) Use

In the protective film 1 of the present embodiment, it is preferable that the surface of one side of the uncoated transparent conductive film in the film for a transparent conductive film laminate is used as an adherend. Thereby, the film for a transparent conductive film laminate (or a transparent conductive film in which a transparent conductive film is laminated on the film for a transparent conductive film laminate) can be protected, and workability can be improved.

In other words, the protective film 1 is attached to the surface of one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, and after the transparent conductive film is laminated on the film for a transparent conductive film layer, it is peeled off at any stage. good. In addition, a hard coat layer or the like may be formed on one side of the unconfined transparent conductive film in the film for a transparent conductive film laminate. In this case, the protective film 1 is attached to the hard coat layer or the like (see FIG. 2).

However, the use of the protective film 1 is not limited thereto, and various articles placed under heating conditions can be used as the adherend.

(4) Physical properties

(4-1) Adhesion

The adhesion of the protective film 1 of the present embodiment to the alkali-free glass is 20 to 300 mN/25 mm, preferably 30 to 250 mN/25 mm, and particularly preferably 40 to 150 mN/25 mm. When the adhesive film is adhered to the film for a transparent conductive film layer by the adhesive force, it is possible to prevent lifting and peeling during the process, and it is easy to bring the peeling force after heating into the range described later.

Further, the adhesive force in the present specification basically means an adhesive force measured by a 180° peeling method according to JIS Z0237:2009, and the measurement sample is set to have a width of 25 mm and a length of 100 mm, and this is measured at 0.5 MPa and 50 ° C. The measurement sample was attached to the adherend after pressurization for 20 minutes, and then allowed to stand under normal pressure, 23 ° C, and 50% RH for 24 hours, and then measured at a peeling speed of 300 mm/min.

(4-2) Peel force before heating

In the protective film 1 of the present embodiment, the protective film 1 is adhered to the surface of one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, and then peeled off when the protective film 1 is peeled off from the film for transparent conductive film laminate. The force (peeling force before heating) is preferably 150 mN/25 mm or less, particularly preferably 20 to 125 mN/25 mm, and further preferably 40 to 100 mN/25 mm. In addition, when a hard coat layer or the like is formed on one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, the protective film 1 is attached to the hard coat layer or the like (the same applies hereinafter).

When the peeling force (peeling force before heating) is 150 mN/25 mm or less, it is possible to effectively prevent the peeling force after heating from becoming excessive. And if When the peeling force is 20 mN/25 mm or more, the protective film 1 can be prevented from peeling off from the film for transparent conductive film lamination in various processes.

(4-3) Peeling force after heating

In the protective film 1 of the present embodiment, the protective film 1 is attached to the surface of one side of the uncoated transparent conductive film in the film for a transparent conductive film layer, and is heated at 150 ° C for 1 hour, and then laminated from the transparent conductive film. The peeling force (peeling force after heating) when the protective film 1 is peeled off by the film is preferably 150 mN/25 mm or less, more preferably 50 to 125 mN/25 mm, and further preferably 75 to 100 mN/25 mm.

When the peeling force (peeling force after heating) is 150 mN/25 mm or less, the protective film 1 can be peeled off from the film for transparent conductive film lamination without any problem. According to the protective film 1 of the present embodiment, since the increase in the adhesive force after heating is suppressed, the peeling property excellent as described above is exhibited.

Further, the peeling force in the present specification basically means an adhesive force measured by a 180° peeling method according to JIS Z0237:2009, and the measurement sample is set to have a width of 25 mm and a length of 100 mm, and this is measured at 0.5 MPa and 50 ° C. The measurement sample was attached to the adherend after pressurization for 20 minutes, and heated at normal pressure at 150 ° C for 1 hour, and then placed under normal pressure, 23 ° C, and 50% RH for 24 hours, at a peeling speed of 300 mm. /minator.

(4-4) Thermal shrinkage after heating

The heat shrinkage rate of the protective film 1 of the present embodiment after heating at 150 ° C for 1 hour is preferably 0.0 to 1.0% in the MD direction (manufacturing line direction) of the substrate 11 , and particularly preferably 0.0 to 0.7%. Preferably, 0.0 to 0.5% is further preferred. And, in the TD (Transverse Direction) of the substrate 11 The direction (the direction orthogonal to the manufacturing line; the width direction) is preferably -0.2 to 0.5%, particularly preferably -0.1 to 0.4%, and further preferably 0.0 to 0.3%. Further, the absolute value of the difference in thermal shrinkage ratio between the protective film 1 and the film for transparent conductive film lamination described later is preferably less than 0.1% in both the MD direction and the TD direction.

When the heat shrinkage rate after the heating of the protective film 1 is within the above range, and the absolute value of the difference in heat shrinkage ratio between the protective film 1 and the transparent conductive film laminated film is within the above range, the protective film can be suppressed from being attached. The bending of the film for transparent conductive film lamination (the film for transparent conductive film lamination with a protective film) can maintain operability satisfactorily.

(5) Method for producing protective film

In order to manufacture the protective film 1 of the present embodiment, as an example, first, a coating liquid containing an adhesive composition P and optionally a diluent solvent is applied to one surface (the upper surface in the first drawing) of the substrate 11 and Drying is performed to form a coating layer of the adhesive composition P.

As the diluent solvent, for example, an aliphatic hydrocarbon such as hexane, heptane or cyclohexane, an aromatic hydrocarbon such as toluene or xylene, a halogenated hydrocarbon such as dichloromethane or ethylene dichloride, methanol, ethanol, propanol or butyl can be used. Alcohol, 1-methoxy-2-propanol and other alcohols, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, butyl acetate and other esters, ethyl cellosolve The cellosolve is a solvent or the like.

The concentration/viscosity of the coating liquid prepared in this manner is not particularly limited as long as it is within the range that can be applied, and may be appropriately selected depending on the situation. For example, the solid content concentration diluted to the adhesive composition P is 10 to 80% by mass. In addition, when a coating solution is obtained, the addition of a diluent solvent or the like is not a requirement, and as long as the viscosity of the adhesive composition P can be applied, So as not to add a dilution solvent.

The drying of the coating liquid can be carried out by air drying, but it is usually carried out by heat treatment (hot air drying is preferred). When the heat treatment is performed, the heating temperature is preferably from 50 to 120 ° C, and particularly preferably from 50 to 100 ° C. Further, the heating time is preferably from 10 seconds to 10 minutes, and particularly preferably from 50 seconds to 2 minutes.

Next, the coating layer of the adhesive composition P is irradiated with an active energy ray, and the coating layer is cured to form an adhesive layer, whereby the protective film 1 is obtained.

As the active energy ray, ultraviolet rays, electron rays, and the like are usually used. The amount of irradiation of the active energy ray varies depending on the type of the energy ray. For example, when it is ultraviolet ray, the amount of light of 50 to 1000 mJ/cm ² is preferably 100 to 500 mJ/cm ² . Further, when it is an electron beam, it is preferably about 10 to 1000 krad.

The irradiation of the above active energy ray can be carried out in the presence of oxygen. In other words, it is possible to irradiate the active energy ray in a normal atmosphere without performing a nitrogen purge or by laminating a coating material on the coating layer of the adhesive composition P. Thereby, the adhesive composition P is sufficiently hardened. That is, the protective film 1 of the present embodiment can be produced by the above-described simple method.

[Thin film for transparent conductive film laminate]

The film 3 for a transparent conductive film laminate with a protective film according to the embodiment of the present invention comprises a film 2 for a transparent conductive film layer 2 and one side of the uncoated transparent film 4 in the film 2 for a transparent conductive film layer. The surface (the surface on the lower side in FIG. 2) is attached to the protective film 1 via the adhesive layer 12.

As an example, the transparent conductive film laminate film 2 of the present embodiment is configured to include a transparent plastic substrate 21 and a surface on one side of the uncoated transparent conductive film 4 in the transparent plastic substrate 21 (in FIG. 2, the lower side) Side surface) The formed hard coat layer 22 and the refractive index matching layer 23 formed on the surface (the upper surface in FIG. 2) on one side of the uncoated transparent conductive film 4 in the transparent plastic substrate 21 are formed. However, the hard coat layer 22 and/or the index matching layer 23 may be omitted or replaced with layers having other functions.

As the transparent plastic substrate 21, those having a transparency and heat resistance can be appropriately selected from plastic films known as conventional optical substrates. Examples of such a plastic film include a polyester film such as a polyethylene terephthalate film, a polybutylene terephthalate film, or a polyethylene naphthalate film, a polyethylene film, and a polypropylene film. , diethyl phthalocyanine film, triethylene fluorene cellulose film, acetonitrile cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate film, poly Styrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyether quinone film, polyimine film, fluororesin film, polyfluorene A plastic film such as an amine film, an acrylic resin film, a norbornene resin film or a cycloolefin resin film, or a laminated film thereof.

In the above, in order to provide appropriate strength to a touch panel or the like, a polyester film, a polycarbonate film, a polyimide film, a norbornene resin film, a cycloolefin resin film, or the like is preferable. Among these, a polyester film is particularly preferable from the viewpoints of transparency and thickness precision, and a polyethylene terephthalate film is further preferable.

The thickness of the transparent plastic substrate 21 is not particularly limited, but is usually 15 to 300 μm, and preferably 30 to 250 μm. Further, the transparent plastic substrate 21 can be subjected to the same surface treatment as the substrate 11 of the protective film 1 described above for the purpose of improving the adhesion to the layer provided on the surface thereof.

The hard coat layer 22 is not particularly limited, and may be formed of a conventionally known material, for example, a material containing an energy ray-curable compound. Examples of the energy ray-curable compound include an acrylic monomer or an oligomer, and specific examples thereof include polyfunctional (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate. Wait.

The thickness of the hard coat layer 22 is not particularly limited, but is usually 1 to 20 μm, and preferably 2 to 10 μm.

The refractive index matching layer 23 is used for a layer in which it is difficult to observe the pattern of the transparent conductive film 4 formed on the transparent conductive film laminate film 2 and to improve the visibility of the touch panel. The index matching layer 23 is composed of, for example, a combination of a high refractive index layer and a low refractive index layer, and the material is not particularly limited.

The thickness of the index matching layer 23 is not particularly limited, but is usually 0.03 to 1 μm, and preferably 0.05 to 0.5 μm.

In the transparent conductive film laminate film 3 with a protective film according to the present embodiment, the transparent conductive film 4 patterned in the exposed area layer of the index matching layer 23 in the transparent conductive film laminate film 2 is obtained to obtain transparent conductive Film. As an example, the transparent conductive film 4 is formed by forming a film by a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, or the like, and then patterning by photolithography, etching, or the like. Further, heat treatment is performed in order to increase the crystallinity of the transparent conductive film before or after the above patterning.

The material of the transparent conductive film 4 can be used without any particular limitation as long as it has both transparency and conductivity. Examples thereof include tin-doped indium oxide (ITO), iridium oxide (IrO ₂ ), and indium oxide. (In ₂ O ₃ ), tin oxide (SnO ₂ ), fluorine-doped tin oxide (FTO), indium oxide-zinc oxide (IZO), zinc oxide (ZnO), gallium-doped zinc oxide (GZO), aluminum doping A transparent conductive metal oxide such as zinc oxide (AZO), molybdenum oxide (MoO ₃ ), or titanium oxide (TiO ₂ ).

In the crystallization process of the transparent conductive film 4, the film 3 for a transparent conductive film layered with a protective film is usually heated to 100 to 180 ° C and heated to about 130 to 150 ° C. Since the protective film 1 exhibits excellent releasability after heating, the protective film 1 can be easily peeled off from the film 2 for transparent conductive film (transparent conductive film) after lamination of the transparent conductive film 4.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, each of the embodiments disclosed in the above embodiments includes all the design changes and equivalents belonging to the technical scope of the present invention.

For example, another layer may be interposed between the substrate 11 and the adhesive layer 12 in the protective film 1, and other layers (for example, a hard coat layer) may be laminated on the surface of the substrate 11 on the side opposite to the side of the adhesive layer 12. Wait).

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the scope of the invention is not limited to the examples and the like.

[Preparation Example 1]

Ethylene oxide-modified pentaerythritol tetraacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester ATM-35E"), molecular weight: 1892, ethylene oxide content: 81 mass, uniformly mixed as an energy ray-curable compound %) 100 parts by mass (converted in solid content; the same below), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one as photoinitiator ( 3 parts by mass, manufactured by BASF Corporation, trade name "IRGACURE 907" And 67 parts by mass of toluene as a diluent solvent, the coating liquid 1 of the adhesive composition having a solid content concentration of about 60% by mass was prepared. In the adhesive composition, the amount of ethylene oxide in the total amount of the energy ray-curable compound was 81% by mass.

[Preparation Example 2]

Ethylene oxide-modified pentaerythritol tetraacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester ATM-35E", molecular weight: 1892, ethylene oxide content: 81 mass, uniformly mixed as an energy ray-curable compound %) as a light ray-curable compound, dipentaerythritol hexaacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester A-DPH", molecular weight: 578), 40 parts by mass, as light 2 parts by mass of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (manufactured by BASF Corporation, trade name "IRGACURE 907"), and as an initiator The coating liquid 2 of the adhesive composition having a solid content concentration of about 60% by mass was prepared by diluting 67 parts by mass of toluene in the solvent. In the adhesive composition, the amount of ethylene oxide in the total amount of the energy ray-curable compound was 49% by mass.

[Preparation Example 3]

Ethylene oxide-modified dipentaerythritol hexaacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester A-DPH-12E", molecular weight: 1106, ethylene oxide content, which is an energy ray-curable compound : 48 mass %) 100 parts by mass of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one as a photoinitiator (manufactured by BASF Corporation) 3 parts by mass of "IRGACURE 907") and 67 parts by mass of toluene as a diluent solvent, a coating liquid 3 of an adhesive composition having a solid content concentration of about 60% by mass was prepared. In the adhesive composition, ethylene oxide is hard in energy rays The amount in the total amount of the compound was 48% by mass.

[Preparation Example 4]

Ethylene oxide-modified dipentaerythritol hexaacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester A-DPH-12E", molecular weight: 1106, ethylene oxide content, which is an energy ray-curable compound 80 parts by mass of 80 parts by mass of dipentaerythritol hexaacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester A-DPH", molecular weight: 578) 20 parts by mass as an energy ray curable compound 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (manufactured by BASF Corporation, trade name "IRGACURE 907") as a photoinitiator, 3 parts by mass And 67 parts by mass of toluene as a diluent solvent, a coating liquid 4 of an adhesive composition having a solid content concentration of about 60% by mass was prepared. In the adhesive composition, the amount of ethylene oxide in the total amount of the energy ray-curable compound was 38% by mass.

[Preparation Example 5]

Ethylene oxide-modified pentaerythritol tetraacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester ATM-35E", molecular weight: 1892, ethylene oxide content: 81 mass, uniformly mixed as an energy ray-curable compound %) 30 parts by mass of dipentaerythritol hexaacrylate (manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., trade name "NK Ester A-DPH", molecular weight: 578), 70 parts by mass as light ray-curable compound, as light 2 parts by mass of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (manufactured by BASF Corporation, trade name "IRGACURE 907"), and as an initiator Diluting the solvent to 67 parts by mass of toluene to prepare a solid concentration of about 60% by mass of the coating liquid 5 of the adhesive composition. In the adhesive composition, the amount of ethylene oxide in the total amount of the energy ray-curable compound was 24% by mass.

[Preparation Example 6]

An acrylate copolymer was prepared by copolymerizing 20 parts by mass of 2-ethylhexyl acrylate, 75 parts by mass of butyl acrylate, and 5 parts by mass of 4-hydroxybutyl acrylate. The molecular weight of the acrylate copolymer was measured by the method described later, and the weight average molecular weight (Mw) was 200,000.

6 parts by mass of hexamethylene diisocyanate-based isocyanurate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX") as a crosslinking agent in an amount of 100 parts by mass of the above acrylate copolymer Further, as the methyl ethyl ketone as a diluent solvent, a coating liquid 6 of an adhesive composition having a solid concentration of about 28% by mass was prepared.

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by a gel permeation chromatography (GPC) method under the following conditions (GPC measurement).

<Measurement conditions>

. GPC measuring device: manufactured by TOSOH CORPORATION, HLC-8020

. GPC column (passed in the following order): manufactured by TOSOH CORPORATION

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

. Determination of solvent: tetrahydrofuran

. Measuring temperature: 40 ° C

[Example 1]

As a substrate, it was dried by Meyer Bar on an easy-adhesion layer of a polyethylene terephthalate film (thickness: 125 μm, heat shrinkage ratio: MD direction 0.5% / TD direction 0.3%) having an easy-adhesion layer. The coating liquid 1 prepared in Preparation Example 1 was applied in such a manner that the film thickness after the film thickness became 15 μm. After the coating layer was dried in an oven at 70 ° C for 1 minute, the coating layer was irradiated with ultraviolet rays having a light amount of 200 mJ/cm ² by a high pressure mercury lamp to form an adhesive layer, thereby obtaining a protective film.

The obtained protective film was attached to a film for a transparent conductive film laminate having a refractive index matching layer on one side and a hard coat layer on the other surface (manufactured by LINTEC Corporation, trade name "OPTERIA HM540-50", thickness: 50 μm, heat The shrinkage ratio: 0.5% in the MD direction / 0.3% in the TD direction) on the hard coat side, thereby obtaining a film for a transparent conductive film laminate with a protective film. In addition, the heat shrinkage rate of the film for the base material and the transparent conductive film laminate was measured by the same method as the test example 3 described later (the same applies hereinafter).

[Example 2]

A film for a transparent conductive film laminate with a protective film was produced in the same manner as in Example 1 except that the coating liquid 2 prepared in Preparation Example 2 was used as the coating liquid of the adhesive composition.

[Example 3]

A film for a transparent conductive film laminate with a protective film was produced in the same manner as in Example 1 except that the coating liquid 3 prepared in Preparation Example 3 was used as the coating liquid of the adhesive composition.

[Example 4]

Coating liquid 4 prepared in Preparation Example 4 was used as a coating for an adhesive composition A film for a transparent conductive film laminate with a protective film was produced in the same manner as in Example 1 except for the above.

[Example 5]

A tape was produced in the same manner as in Example 1 except that a polyethylene terephthalate film having an easy-adhesion layer (thickness: 125 μm, heat shrinkage ratio: 0.4% in the MD direction/0.2% in the TD direction) was used as the substrate. A film for laminating a transparent conductive film of a protective film.

[Comparative Example 1]

A film for a transparent conductive film laminate with a protective film was produced in the same manner as in Example 1 except that the coating liquid 5 prepared in Preparation Example 5 was used as the coating liquid of the adhesive composition.

[Comparative Example 2]

As a substrate, on an easy-adhesion layer of a polyethylene terephthalate film having an easy-adhesion layer (thickness: 125 μm, heat shrinkage ratio: 0.5% in the MD direction/0.3% in the TD direction), by an applicator ( The coating liquid 6 prepared in Preparation Example 6 was applied in such a manner that the film thickness after drying became 20 μm, and the coating layer was dried in an oven at 90 ° C for 1 minute. A release film (manufactured by LINTEC Corporation, trade name "SP-PET381031") which was subjected to a release treatment with an oxime-based release agent was laminated on the coating layer so that the release-treated surface and the coating layer were etched. Thereafter, the adhesive layer was formed by air drying in an environment of 23 ° C and 50% RH for 7 days to obtain a protective film.

A film for a transparent conductive film laminate with a protective film was produced in the same manner as in Example 1 using the above protective film.

[Test Example 1] (Measurement of adhesion)

The protective film prepared in the examples and the comparative examples was cut into a test piece of a length of 100 mm and a width of 25 mm, and was attached to the alkali-free glass at a pressure of 0.5 MPa and 50 ° C for 20 minutes, in a standard environment (23). Leave at °C, 50% RH) for 24 hours. Thereafter, in a standard environment (23 ° C, 50% RH), the protective film side was peeled off at a peeling angle of 180° and a peeling speed of 300 mm/min using a tensile tester, and the adhesion (mN/25 mm) was measured. .

[Test Example 2] (Measurement of peeling force)

The film for a transparent conductive film laminate with a protective film prepared in the examples and the comparative examples was cut into a test piece of a length of 100 mm and a width of 25 mm, and a tensile tester was used under a standard environment (23 ° C, 50% RH). The peeling angle of 180° and the peeling speed of 300 mm/min peeled off the protective film side, and the force required for peeling (peeling force; mN/25 mm) (peeling force before heating) was measured.

Then, the test piece was heated at 150 ° C for 1 hour in an oven, and then left in a standard environment (23 ° C, 50% RH) for 24 hours, and the peeling force (peeling force after heating) was measured in the same manner as above. The results are shown in Table 1.

[Test Example 3] (Measurement of heat shrinkage rate)

From the protective film produced in the examples and the comparative examples, a test piece of 100 mm × 100 mm was cut out, and a standard line was marked from the end in the MD direction and the TD direction on one side to the inner side of 10 mm, and the initial standard line interval was measured. Next, the test piece was heated at 150 ° C for 1 hour in an oven, and then placed under a standard environment (23 ° C, 50% RH) for 24 hours. The dimensions after the test were measured at the same positions as before the test, and the heat shrinkage ratio (%) in the MD direction and the TD direction was determined by the following formula. The results are shown in Table 1.

Heat shrinkage rate (%) = {(l _{0 -} l ₁ ) / l ₀ } × 100

l ₁ : size after test (mm)

l ₀ : initial standard line spacing (mm)

[Test Example 4] (Measurement of the amount of bending)

Test pieces of 100 mm × 100 mm were cut out from the protective film prepared in the examples and the comparative examples, and heated at 150 ° C for 1 hour in an oven, and then left in a standard environment (23 ° C, 50% RH) for 24 hours. Next, the test piece was placed on a water platform, and the maximum value of the vertical distance (mm) from the table top was measured, and this was made into the bending amount (mm). The results are shown in Table 1.

As is clear from Table 1, the increase in the peeling force after heating of the protective film produced in Examples 1 to 5 was suppressed. Further, the bending of the protective film produced in Examples 1 to 4 after heating was also suppressed.

[Industrial availability]

The protective film of the present invention is useful for improving the protection and handleability of a film for a transparent conductive film laminate or a transparent conductive film.

1‧‧‧Protective film

11‧‧‧Substrate

12‧‧‧Adhesive layer

Claims (11)

A protective film comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the adhesive layer is composed of an adhesive which hardens the adhesive composition, and the adhesive composition contains 60 One or two or more kinds of energy ray-curable compounds having a molecular weight of 500 to 10,000 or more by mass% or more, and the adhesion of the protective film to the alkali-free glass is 20 to 300 mN/25 mm. The protective film according to claim 1, wherein at least one of the energy ray-curable compounds has an oxyalkylene chain, and the amount of the alkylene oxide in the total amount of the energy ray-curable compound is 35 to 95 mass. %. The protective film according to the second aspect of the invention, wherein the energy ray-curable compound having the oxyalkylene chain is 40% by mass or more in the total amount of the energy ray-curable compound. The protective film according to claim 1, wherein the energy ray curable compound is a polyfunctional (meth) acrylate. The protective film according to claim 4, wherein the polyfunctional (meth) acrylate is a trifunctional or higher (meth) acrylate. The protective film according to claim 1, wherein the adhesive composition does not contain an adhesive component having a weight average molecular weight of more than 10,000. The protective film according to the first aspect of the invention, wherein the protective film is attached to the transparent conductive film laminate film and has an unlaminated transparent conductive layer. The surface on one side of the film is peeled off at any stage after the transparent conductive film is laminated on the film for transparent conductive film laminate. The protective film according to claim 7, wherein a hard coat layer is formed on one side of the uncoated transparent conductive film in the transparent conductive film laminate film, and the protective film is attached to the hard coat layer. A method for producing a protective film according to any one of claims 1 to 8, wherein the coating of the adhesive composition is applied to one surface of the substrate. The liquid is dried to form a coating layer of the above-mentioned adhesive composition, and the coating layer is irradiated with energy rays to cure the coating layer to form an adhesive layer. The method for producing a protective film according to claim 9, wherein the irradiation of the energy ray of the coating layer is performed in the presence of oxygen. A film for a transparent conductive film laminate with a protective film, comprising: a film for a transparent conductive film laminate; and the protective film according to any one of claims 1 to 8, which is attached to the transparent conductive material The surface of one side of the film for the film laminate which is not laminated with the transparent conductive film.