KR102538731B1 - Laminated film for supporting the transparent conductive layer - Google Patents

Abstract

The laminated film 20 has a base film 16 for supporting the transparent conductive layer 17 and a protective film 14 supporting the base film 16 via the pressure-sensitive adhesive layer 15 . The base film 16 and the protective film 14 each contain a cycloolefin resin. The film thickness of the base film 16 is 5 μm or more and 40 μm or less. The heat shrinkage rate A (%) of the width direction at the time of heating at 140 degreeC for 90 minutes of the base film 16 is 0.01 % or more and 0.20 % or less. When the thermal contraction rate of the protective film 14 in the width direction at the time of heating at 140°C for 90 minutes is set to B (%), it is 0.02 ≤ A/B ≤ 0.50.

Description

Laminated film for supporting the transparent conductive layer

This invention relates to the laminated|multilayer film for support of a transparent conductive layer used for manufacture of a touch sensor panel, for example.

Most mobile displays are equipped with touch panels. In this touch panel, a transparent conductive film in which a transparent conductive layer is supported by a base film is often used. This transparent conductive film is obtained by peeling the protective film together with the pressure-sensitive adhesive layer from a laminate in which a transparent conductive layer is formed by laminating a base film and a protective film supporting a transparent conductive layer through an pressure-sensitive adhesive layer.

Here, an example of a laminate in which the transparent conductive layer is formed is disclosed in Patent Literature 1. In Patent Literature 1, PET (polyethylene terephthalate) resin is used for the base film and the protective film, and the absolute value of the difference in thermal shrinkage between the base film and the protective film is reduced, thereby suppressing the generation of curl.

However, since the birefringence of the PET resin is very high, when a base film containing the PET resin is combined with a display, iridescence occurs. In addition, when a protective film made of PET resin is used, foreign matter detection sensitivity is lowered in the inspection step. Therefore, using a cycloolefin resin (COP resin) for a base film and a protective film is being studied. For example, in Patent Literature 2, COP resin is used for the base film and the protective film, and the amount and direction of curl are controlled by suppressing dimensional fluctuations of the base film and the protective film due to heat shrinkage.

Japanese Patent Publication No. 5506011 (see claim 1, paragraphs [0032], [0076], FIGS. 1, 2, etc.) Japanese Unexamined Patent Publication No. 2016-107503 (see claim 1, paragraphs [0095], [0105], [0106], Fig. 1, etc.)

By the way, in recent years, flexibility is requested|required of a display, and flexibility is requested|required similarly also in a touch panel. To cope with this flexibility, a further thinned transparent conductive film is required. In addition, roll-to-roll roll-to-roll production of transparent conductive films is also demanded in order to improve productivity.

Then, using the protective film containing COP resin which suppressed the dimensional change by heat shrinkage, and the thin base film containing COP resin, the protective film and base film were laminated|stacked with the adhesive layer interposed, and the base film After forming a transparent conductive layer on the base film, peeling the protective film from the base film together with the pressure-sensitive adhesive layer to produce a thinned transparent conductive film. As a result, in the process of peeling the protective film from the base film, the transparent conductive film is deformed. It turns out that this happens. If this base film is thin, when peeling a protective film, it is thought that the cause is that the base film is pulled to the protective film side via the adhesive layer, and wrinkles arise in the base film. If the transparent conductive film is deformed, the transparent conductive layer may be damaged (eg broken) when the transparent conductive film is wound into a roll shape.

In particular, in Patent Document 2, since the thermal shrinkage rate of the protective film is small, the shrinkage stress generated during heat processing is small, and the glass transition temperature (Tg) of the protective film is low, so the stress generated during heat processing is relieved. . Therefore, sufficient residual stress cannot be obtained, and it is necessary to peel the protective film with a high peeling force. For this reason, when the base film is made thin, it is considered that the base film tends to be pulled toward the protective film side in the peeling step, and the transparent conductive film becomes more easily deformed.

The present invention has been made to solve the above problem, and its object is to be able to suppress deformation of the transparent conductive film at the time of peeling of the protective film after forming the transparent conductive layer even if the base film is thin, thereby making it thin. It is to provide a laminated film for support of a transparent conductive layer that makes it possible to manufacture the transparent conductive film of the above with high productivity.

The laminated film of one aspect of the present invention is a laminated film for supporting a transparent conductive layer of a transparent conductive film,

A base film for supporting the transparent conductive layer;

It has a protective film that supports the base film through an adhesive layer,

The base film and the protective film each include a cycloolefin resin,

The film thickness of the base film is 5 μm or more and 40 μm or less,

The heat shrinkage rate A (%) of the base film in the width direction at the time of heating at 140 ° C. for 90 minutes is 0.01% or more and 0.20% or less,

When the thermal contraction rate of the protective film in the width direction at the time of heating at 140 ° C. for 90 minutes is B (%),

0.02 ≤ A/B ≤ 0.50

am.

According to the structure of the laminated film, even if the base film is thin, deformation of the base film and the transparent conductive layer (transparent conductive film) can be suppressed during peeling of the protective film after forming the transparent conductive layer on the base film. there is. This makes it possible to manufacture a thin transparent conductive film with high productivity by roll-to-roll.

1 is a cross-sectional view showing a schematic configuration of a touch panel display device according to an embodiment of the present invention.
2 is a cross-sectional view showing another configuration of the touch panel display device.
FIG. 3 is a flow chart showing the flow of a method for manufacturing a transparent conductive film used in the touch sensor panel of the touch panel display device of FIG. 1 or 2 .
4 is a cross-sectional view showing a manufacturing process of the transparent conductive film.
5 : is explanatory drawing which shows the outline structure of the manufacturing apparatus which manufactures the optical film contained in the laminated|multilayer film used for manufacture of the said transparent conductive film.
6 is a flow chart showing the flow of the method for manufacturing the optical film.

An embodiment of the present invention will be described based on the drawings as follows. In addition, in this specification, when expressing a numerical range as A-B, the value of the lower limit A and the upper limit B shall be included in the numerical range.

[Touch panel display device]

1 is a cross-sectional view showing a schematic configuration of a touch panel display device 1 of the present embodiment. A touch panel display device (1) is configured with a touch sensor panel (3) on a display unit (2). The display unit 2 is configured of, for example, a liquid crystal display device, but may be configured of another display device such as an organic EL (Electro-Luminescence) display device also called OLED (Organic Light-Emitting Diode).

In the touch sensor panel 3, an adhesive layer 13, a transparent conductive film 12, an adhesive layer 13, a transparent conductive film 12, and an adhesive layer 13 are formed on a glass substrate 11 as a transparent substrate in this order. It is made up of layers. Each transparent conductive film 12 is formed by laminating a base film 16 and a transparent conductive layer 17 in this order. Among the two transparent conductive films 12, the transparent conductive film 12 closer to the glass substrate 11 is located so that the base film 16 is on the glass substrate 11 side than the transparent conductive layer 17. there is. The other transparent conductive film 12 (transparent conductive film 12 on the side closer to the display unit 2) is positioned so that the base film 16 is on the display unit 2 side rather than the transparent conductive layer 17.

2 is a cross-sectional view showing another configuration of the touch panel display device 1. As shown in FIG. As shown in the same figure, the touch sensor panel 3 of the touch panel display device 1 includes an adhesive layer 13, a transparent conductive film 12, and an adhesive layer 13 on a glass substrate 11 in this order. It may be constituted by laminating with . In this configuration, the transparent conductive film 12 is positioned so that the base film 16 is closer to the display unit 2 side than the transparent conductive layer 17 .

1 or 2, the transparent conductive layer 17 can be formed of, for example, indium oxide (ITO) containing tin oxide or a conductive film containing metal nanowires. From the viewpoint of not breaking the transparent conductive layer 17 even when bending is repeated in consideration of flexibility and exhibiting good bending durability, it is preferable to configure the transparent conductive layer 17 with a conductive film containing metal nanowires. desirable. The adhesive layer 13 is composed of, for example, an optical adhesive film. The transparent conductive film 12 can be manufactured, for example, as follows.

(Method of manufacturing transparent conductive film)

3 is a flow chart showing the flow of the manufacturing method of the transparent conductive film 12. 4 is a sectional view showing a manufacturing process of the transparent conductive film 12 . The transparent conductive film 12 includes a laminated film preparation step (S1), a transparent conductive layer forming step (S2), and a protective film peeling step (S3).

(S1: Laminate Film Preparation Process)

In S1, the laminated film 20 is prepared. This laminated film 20 is formed by laminating a protective film 14 and a base film 16 with an adhesive layer 15 interposed therebetween. The base film 16 is composed of a thin film having a thickness of 5 µm or more and 40 µm or less, as will be described later. Here, the laminated film 20 is previously wound up in a roll shape. In addition, a cured resin layer (hard coat layer) may be formed on at least one surface of the base film 16 . Details of this laminated film 20 will be described later.

(S2: Transparent Conductive Layer Forming Step)

In S2, the laminated film 20 wound in a roll shape is unwound, and the transparent conductive layer 17 is formed on the base film 16 of the unwound laminated film 20 to form the laminated body 10 with a transparent conductive layer. get For example, by conveying the laminated film 20 in a vacuum apparatus and forming the transparent conductive layer 17 on the base film 16 by a vacuum process such as sputtering or vapor deposition, a transparent conductive layer formed laminate ( 10) is obtained. Alternatively, the transparent conductive layer 17 may be patterned into a desired shape by etching. Alternatively, the composition constituting the transparent conductive layer 17 may be applied to the surface of the base film 16 and dried to form the transparent conductive layer 17 to obtain the laminate 10 with a transparent conductive layer. . Either way, the obtained laminate 10 with a transparent conductive layer is wound up in a roll shape.

(S3; protective film peeling process)

In S3, the laminate 10 with a transparent conductive layer wound into a roll is unwound, and the protective film 14 is peeled together with the pressure-sensitive adhesive layer 15 from the laminate 10 with a transparent conductive layer. Thereby, the thin transparent conductive film 12 which has the transparent conductive layer 17 on the thin base film 16 is obtained. The obtained transparent conductive film 12 is wound up in roll shape.

In this way, according to the method for manufacturing the transparent conductive film 12 described above, the thin transparent conductive film 12 can be manufactured roll-to-roll by using the laminated film 20 having the thin base film 16. can be manufactured This makes it possible to manufacture the thin transparent conductive film 12 with high productivity.

[Details of laminated film]

Next, the details of the laminated film 20 mentioned above are demonstrated. The laminated film 20 is a laminated film for support of the transparent conductive layer 17 included in the transparent conductive film 12 . This laminated film 20 has the base film 16 for supporting the transparent conductive layer 17, and the protective film 14 which supports the base film 16 via the adhesive layer 15.

The base film 16 and the protective film 14 each contain a cycloolefin resin (COP resin). This can solve problems that arise when, for example, PET resin is used as a film material. That is, it is possible to avoid the occurrence of iridescence on the display and the decrease in foreign matter detection sensitivity in the inspection process.

The film thickness of the base film 16 is 5 μm or more and 40 μm or less. When the film thickness of the base film 16 is within the above range, cracks occur in the base film 16 during bending and conveyance of the transparent conductive film 12, and the transparent conductive layer 17 is damaged (eg broken). can reduce it Therefore, the thin transparent conductive film 12 can be manufactured with high productivity by roll-to-roll. That is, the laminated film 20 suitable for manufacturing the thin transparent conductive film 12 with high productivity can be realized.

In this regard, since the base film 16 is too thin if the film thickness of the base film 16 is less than 5 μm, when conveying the transparent conductive film 12 while bending it with a conveyance roll, the base film 16 It becomes prone to cracking, and as a result, the transparent conductive layer 17 on the base film 16 breaks, and poor conduction tends to occur. Conversely, when the film thickness of the base film 16 exceeds 40 μm, the transparent conductive layer 17 on the base film 16 rolls at the time of bending in the roll at the time of conveyance of the transparent conductive film 12. It is stretched in the circumferential direction and easily broken, which also tends to cause poor conduction.

Moreover, the heat shrinkage rate A (%) of the width direction at the time of heating at 140 degreeC for 90 minutes of the base film 16 is 0.01 % or more and 0.20 % or less. In this way, damage to the transparent conductive layer 17 can be suppressed at the time of heat processing (including drying) of the transparent conductive layer 17 and at the time of peeling of the protective film 14, and the transparent conductive film 12 The laminated film 20 suitable for manufacture of can be realized.

In this regard, when the thermal contraction rate A exceeds 0.20%, since the thermal shrinkage of the base film 16 at the time of heat processing of the transparent conductive layer 17 is too large, the transparent conductive layer 17 on the base film 16 It is considered that the contraction of the base film 16 cannot be followed and is easily broken, so that poor conduction tends to occur. Conversely, when the thermal contraction rate A is less than 0.01%, the shrinkage stress generated in the base film 16 during heat processing of the transparent conductive layer 17 is small, and sufficient residual stress is not obtained. For this reason, it becomes difficult to uniformly peel the protective film 14 from the base film 16, and the point where the base film 16 is partially pulled toward the protective film 14 side arises. At such a point, it is considered that the transparent conductive layer 17 on the base film 16 is partially broken, and poor conduction tends to occur.

In addition, when the thermal contraction rate in the width direction at the time of heating at 140 ° C. for 90 minutes of the protective film 14 is B (%),

0.02 ≤ A/B ≤ 0.50

am. By satisfying this conditional expression, it becomes possible to peel the protective film 14 from the base film 16 using the difference in thermal contraction rate of the base film 16 and the protective film 14. Therefore, it becomes possible to peel off the protective film 14 easily, without weakening the adhesive force of the adhesive layer 15.

If it is estimated about the expression mechanism of this action effect, it is as follows. That is, when the laminated film 20 is heated in the process of forming the transparent conductive layer 17, the protective film 14 and the base film 16 have different shrinkage forces during heating, and then when cooled (normal temperature ), residual stress is generated in the pressure-sensitive adhesive layer 15 and the protective film 14. When peeling the protective film 14 from the roll-shaped laminated film 20, not only tension in the longitudinal direction by the peeling roll but also shrinkage in the width direction due to the residual stress occurs, so the peeling triggers protection It becomes possible to peel the film 14 with less force.

In this way, when the protective film 14 is peeled off easily, when the protective film 14 is peeled off, it becomes difficult for the base film 16 to be pulled toward the protective film 14 side, and the base film 16 supported by the It becomes difficult for the transparent conductive layer 17 to be pulled toward the protective film 14 side. As a result, deformation of the transparent conductive film 12 at the time of peeling of the protective film 14 (creation of wrinkles or folds) can be reduced.

In this regard, when A/B exceeds 0.50, since the difference in thermal shrinkage rate between the base film 16 and the protective film 14 is small (because A/B approaches 1), using the difference in thermal shrinkage amount It becomes difficult to peel the protective film 14 from the base film 16. As a result, it becomes necessary to peel the protective film 14 with a high peeling force. When the peeling force of the protective film 14 is high, the transparent conductive film 12 is pulled toward the protective film 14 side during peeling and is easily deformed. On the other hand, if A/B is less than 0.02, the thermal contraction rate B of the protective film 14 becomes too large with respect to the thermal contraction rate A of the base film 16. In this case, when the transparent conductive layer 17 is heat processed, the protective film 14 thermally shrinks greatly and the edge of the protective film 14 is easily peeled off. ), it becomes difficult to uniformly peel in the width direction. As a result, at the time of peeling of the protective film 14, wrinkles easily form in the base film 16, and the transparent conductive film 12 becomes easy to deform.

Moreover, since the protective film 14 can be peeled easily without weakening the adhesive force of the adhesive layer 15, the adhesive force of the adhesive layer 15 protects the protective film 14 from the base film during transport before peeling. (16) The situation of peeling off can be avoided. Therefore, the case where the peeled protective film 14 is rolled up by the conveyance roll and the laminate 10 with a transparent conductive layer is broken is also eliminated.

The film thickness of the protective film 14 is 40 µm or more and 100 µm or less, and is preferably thicker than the film thickness of the base film 16 . In this configuration, the shrinkage force due to the heat of the protective film 14 can be appropriately generated with respect to the thickness of the base film 16 . Thereby, during conveyance at the time of heat processing of the transparent conductive layer 17, it is possible to reduce the occurrence of wrinkles in the base film 16 under the influence of thermal contraction of the protective film 14. Therefore, when the transparent conductive layer forming layered product 10 is wound up, damage to the transparent conductive layer 17 on the base film 16 can be reduced. In addition, the mechanical strength of the protective film 14 is sufficiently ensured, and the damage (for example, cracking) of the protective film 14 during transportation is sufficiently reduced.

In addition, as described above, from the viewpoint of exhibiting good bending durability, the transparent conductive layer 17 is preferably composed of a conductive film containing metal nanowires. From this, it can be said that the substrate film 16 preferably constitutes the laminated film 20 for supporting a conductive film containing metal nanowires as the transparent conductive layer 17 .

[About the materials of each floor]

Next, materials and the like of each layer constituting the above-described laminate 10 with a transparent conductive layer will be described.

<Transparent Conductive Film>

(substrate film)

It is preferable that the base film contains a cycloolefin resin from the viewpoint of easy control of optical properties.

The cycloolefin resin is not particularly limited as long as it is a resin having a unit of a monomer composed of a cyclic olefin (cycloolefin). As the cycloolefin resin used for the base film, either a cycloolefin polymer (COP) or a cycloolefin copolymer (COC) may be used. The cycloolefin copolymer refers to an amorphous cyclic olefin resin that is a copolymer of a cyclic olefin and an olefin such as ethylene.

As said cyclic olefin, polycyclic cyclic olefin and monocyclic cyclic olefin exist. Examples of such polycyclic cyclic olefins include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, butylnorbornene, dicyclopentadiene, and dihydrodicyclopenta. Diene, methyldicyclopentadiene, dimethyldicyclopentadiene, tetracyclododecene, methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, tetracyclopentadiene, etc. are mentioned. Moreover, cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, cyclododecatriene etc. are mentioned as a monocyclic cyclic olefin.

Cycloolefin resins can also be obtained commercially, and examples thereof include “ZEONOR” by Nippon Zeon, “ARTON” by JSR, “TOPAS” by Polyplastic, and “APEL” by Mitsui Chemicals. .

The surface of the base film is previously subjected to an etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, or an undercoat treatment to improve adhesion to the transparent conductive layer formed on the base film. you can improve it. In addition, before forming the transparent conductive layer, the surface of the substrate film may be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

It is preferable that it is 130 degreeC or more, and, as for the glass transition temperature of the cycloolefin resin which forms a base film, it is more preferable that it is 140 degreeC or more. Thereby, generation|occurrence|production of curl after a heat treatment process can be suppressed, dimensional stability can be improved, and the yield of a subsequent process can be ensured.

(transparent conductive layer)

The material constituting the transparent conductive layer is not particularly limited as long as it contains an inorganic material, and is from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten. A metal oxide of at least one type of metal selected from is preferably used. The said metal oxide may further contain the metal atom shown in the said group as needed. For example, indium oxide (ITO) containing tin oxide, tin oxide (ATO) containing antimony, and the like are preferably used.

The thickness of the transparent conductive layer is not particularly limited, but is preferably 10 nm or more in order to obtain a continuous film having good conductivity with a surface resistance of 1×10 ³ Ω/□ or less. The film thickness is preferably in the range of 15 to 35 nm, more preferably in the range of 20 to 30 nm, in order to cause a decrease in transparency or the like when the film thickness is too thick. When the thickness of the transparent conductive layer is less than 10 nm, the electrical resistance on the surface of the film increases, and it becomes difficult to form a continuous film. Moreover, when the thickness of a transparent conductive layer exceeds 35 nm, the fall of transparency etc. may be caused.

The method for forming the transparent conductive layer is not particularly limited, and conventionally known methods can be employed. Specifically, dry processes such as a vacuum deposition method, a sputtering method, and an ion plating method can be exemplified. In addition, an appropriate method may be employed according to the required film thickness.

The transparent conductive layer can be crystallized by performing heat annealing treatment (for example, in an air atmosphere at 80 to 150°C for about 30 to 90 minutes) as needed. By crystallizing the transparent conductive layer, in addition to reducing the resistance of the transparent conductive layer, transparency and durability are improved. The means for converting the amorphous transparent conductive layer to crystalline is not particularly limited, but an air circulation oven, an IR heater, or the like is used.

Regarding the definition of "crystalline", a transparent conductive film in which a transparent conductive layer is formed on a base film is immersed in hydrochloric acid having a concentration of 5% by weight at 20 ° C. for 15 minutes, then washed with water and dried, and the resistance between terminals of 15 mm is measured with a tester, and when the resistance between the terminals does not exceed 10 kΩ, conversion of the ITO film to crystalline is assumed to have been completed. In addition, the measurement of surface resistance value can be measured by the 4-probe method according to JISK7194.

Alternatively, the transparent conductive layer may be patterned by etching or the like. Regarding patterning of the transparent conductive layer, it can be carried out using a conventionally known photolithography technique. As the etchant, an acid is preferably used. Examples of the acid include inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid and phosphoric acid, organic acids such as acetic acid, mixtures thereof, and aqueous solutions thereof. For example, in a transparent conductive film used for a capacitive touch panel or a matrix resistive touch panel, the transparent conductive layer is preferably patterned in a stripe shape. In the case of patterning the transparent conductive layer by etching, if the transparent conductive layer is crystallized first, patterning by etching may be difficult. Therefore, it is preferable to perform the annealing treatment of the transparent conductive layer after patterning the transparent conductive layer.

When the transparent conductive layer is formed by a dry process such as sputtering, the substrate film is conveyed in a laminated state on the protective film with an adhesive layer interposed therebetween, the transparent conductive layer is formed on the substrate film, and roll-to-roll It is preferable to continuously process as a long transparent conductive layer forming laminate with a roll. By setting it as a laminate with a transparent conductive layer, in the roll-to-roll manufacturing method, breakage of the laminate with a transparent conductive layer can be prevented, and the yield of subsequent steps can be secured.

《Metal Nanowire》

As a material constituting the transparent conductive layer, metal nanowires can also be used. A metal nanowire refers to a conductive material whose material is metal, its shape is needle-like or filamentous, and its diameter is nanometer size. The metal nanowire may be linear or curved. When a transparent conductive layer composed of metal nanowires is used, a good electrical conduction path can be formed even with a small amount of metal nanowires because the metal nanowires become a network, and a transparent conductive film with low electrical resistance can be obtained. can In addition, by forming the metal nanowires into a net shape, openings are formed in the gaps between the nets, so that a transparent conductive film having high light transmittance can be obtained.

The ratio of the thickness d to the length L (aspect ratio: L/d) of the metal nanowire is preferably in the range of 10 to 100000, more preferably in the range of 50 to 100000, and particularly preferably 100 It is within the range of to 10000. In this way, when a metal nanowire having a large aspect ratio is used, the metal nanowires cross well, and a small amount of the metal nanowire can develop higher conductivity. As a result, a transparent conductive film having high light transmittance can be obtained.

Further, in the present specification, "thickness of metal nanowire" means the diameter when the cross section of the metal nanowire is circular, and when it is elliptical, it means its short diameter, and when it is polygonal, it means the longest diagonal it means. The thickness and length of the metal nanowires can be confirmed using a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowire is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably within the range of 10 to 100 nm, and most preferably within the range of 10 to 50 nm . Within this range, a transparent conductive layer having high light transmittance can be formed.

The length of the metal nanowire is preferably in the range of 2.5 to 1000 μm, more preferably in the range of 10 to 500 μm, and particularly preferably in the range of 20 to 100 μm. Within this range, a transparent conductive film with high conductivity can be obtained.

As the metal constituting the metal nanowire, any appropriate metal may be used as long as it is a highly conductive metal. As a metal which comprises the said metal nanowire, silver, gold, copper, nickel etc. are mentioned, for example. Moreover, you may use the material which plated these metals (for example, gold plating process). Among them, silver or copper is preferable from the viewpoint of conductivity.

As a method for producing the metal nanowire, any suitable method may be employed. For example, a method of reducing silver nitrate in a solution, a method of applying a voltage or current applied to the surface of a precursor from the tip of a probe, extracting metal nanowires from the tip of the probe, and continuously forming the metal nanowires. there is. In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by reducing a liquid phase of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone.

Silver nanowires of uniform size are described, for example, in Xia, Y. et al., Chem. Mater. (2002), 14, 4736-4745, Xia, Y. et al., Nano letters (2003) 3 (7), mass production is possible according to the method described in 955-960.

The transparent conductive layer can be formed by coating a composition for forming a transparent conductive layer containing the metal nanowires on the transparent substrate. More specifically, a dispersion (composition for forming a transparent conductive layer) in which the metal nanowires are dispersed in a solvent is applied onto the transparent substrate, and then the coated layer is dried to form a transparent conductive layer.

Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, and aromatic solvents. From the viewpoint of reducing the environmental load, it is preferable to use water.

The dispersion concentration of the metal nanowire in the composition for forming a transparent conductive layer containing the metal nanowire is preferably in the range of 0.1 to 1% by mass. Within this range, a transparent conductive layer having excellent conductivity and light transmittance can be formed.

The composition for forming a transparent conductive layer including the metal nanowires may further contain any suitable additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of metal nanowires and a surfactant that prevents aggregation of metal nanowires. The type, number and amount of additives used may be appropriately set according to the purpose. In addition, the composition for forming the transparent conductive layer may contain any suitable binder resin as needed, as long as the effects of the present invention are obtained.

As a method of applying the composition for forming a transparent conductive layer including the metal nanowires, any suitable method may be employed. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, relief printing, intaglio printing, and gravure printing.

As a method for drying the applied layer, any suitable drying method (for example, natural drying, blowing drying, heat drying) can be employed. For example, in the case of heat drying, the drying temperature is typically in the range of 100 to 200°C, and the drying time is typically in the range of 1 to 10 minutes.

When the transparent conductive layer contains metal nanowires, the thickness of the transparent conductive layer is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 3 μm, particularly preferably It is in the range of 0.1-1 micrometer. Within this range, a transparent conductive film having excellent conductivity and light transmittance can be obtained.

When the transparent conductive layer contains metal nanowires, the total light transmittance of the transparent conductive layer is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more.

(Adhesive layer)

As the pressure-sensitive adhesive layer, as long as it has transparency, it can be used without particular limitation. Specifically, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy-based rubbers, fluorine-based rubbers, natural rubbers, and synthetic rubbers. A polymer such as a base polymer can be appropriately selected and used. In particular, acrylic adhesives are preferably used in view of excellent optical transparency, appropriate adhesive properties such as wettability, cohesiveness and adhesiveness, and excellent weather resistance and heat resistance.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and a method of applying the pressure-sensitive adhesive composition to a release liner and transferring the pressure-sensitive adhesive composition to a protective film after drying (transfer method), a method of directly applying the pressure-sensitive adhesive composition to the protective film and drying it (direct yarn method) ) or co-extrusion. Moreover, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, etc. can also be used suitably for an adhesive as needed.

The preferred thickness of the pressure-sensitive adhesive layer is 5 µm to 100 µm, more preferably 10 µm to 50 µm, and still more preferably 15 µm to 35 µm.

(protective film)

The protective film is preferably formed of an amorphous resin in consideration of handling properties such as winding with a roll. As the amorphous resin, it is preferable to use a cycloolefin resin having excellent transparency, mechanical strength, thermal stability, water barrier properties, isotropy, and the like. The cycloolefin resin is also preferable from the viewpoint of suppressing curling after the heat treatment step and improving dimensional stability.

It is preferable that it is 130 degreeC or more, and, as for the glass transition temperature of the amorphous resin which forms a protective film, it is more preferable that it is 140 degreeC or more. In this way, curling after the heat treatment process can be suppressed, dimensional stability can be improved, and the yield of the subsequent process can be secured.

Like the base film, the surface of the protective film is subjected to an etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, or an undercoat treatment in advance to improve adhesion to the adhesive layer on the protective film. You can do it. In addition, before forming the pressure-sensitive adhesive layer, the surface of the protective film may be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like as needed.

The thickness of the protective film is preferably 10 to 150 μm, more preferably 30 to 110 μm, and still more preferably 40 to 100 μm. In this thickness range, it is possible to reduce the formation of wrinkles in the base film under the influence of heat shrinkage of the protective film during transportation of the laminate during heat processing of the transparent conductive layer while ensuring the mechanical strength of the protective film.

[Film manufacturing method]

The above-described base film and protective film (hereinafter collectively also referred to as "optical film") can be produced by, for example, a solution cast film forming method. Fig. 5 is an explanatory diagram showing a schematic configuration of the optical film manufacturing apparatus 31 of the present embodiment, and Fig. 6 is a flow chart showing the flow of the optical film manufacturing method. The optical film manufacturing method of the present embodiment is a method for manufacturing an optical film by a solution casting film forming method, including a stirring preparation step (S31), a casting step (S32), a peeling step (S33), and a first drying step (S34 ), an extending process (S35), a 2nd drying process (S36), a cutting process (S37), an embossing process (S38), and a winding process (S39) are included. Hereinafter, each process is demonstrated.

<Stirring preparation process>

In the stirring preparation step, at least resin and the solvent are stirred in the stirring vessel 51 of the stirring device 50 to prepare dope which is cast on the support body 33 (endless belt). As the resin, for example, a cycloolefin resin can be used. As the solvent, a mixed solvent of a good solvent and a poor solvent can be used. In addition, a good solvent refers to an organic solvent having the property of dissolving resin (solubility), 1,3-dioxolane, THF (tetrahydrofuran), methyl ethyl ketone, acetone, methyl acetate, methylene chloride (dichloromethane) etc. corresponds to this. On the other hand, a poor solvent refers to a solvent that does not have the property of dissolving a resin alone, and methanol, ethanol, and the like correspond to this.

<Flexible Process>

In the casting step, the dope prepared in the stirring preparation step is fed to the casting die 32 through a conduit via a pressurized metering gear pump or the like, and a supporting body 33 made of a rotationally driven stainless steel endless belt that feeds it endlessly. Dope is cast from the casting die 32 at the casting position of the phase. And flexible dope is dried on the support body 33, and the flexible film 35 (web) is formed. The inclination of the casting die 32, that is, the discharge direction of the dope from the casting die 32 to the support 33, is an angle to the normal of the surface of the support 33 (the surface on which the dope is cast), and is 0° to 90 degrees. What is necessary is just to set suitably so that it may fall within the range of °.

The support body 33 is held by a pair of rolls 33a and 33b and a plurality of rolls (not shown) positioned between them. A driving device (not shown) for applying tension to the support 33 is provided on one or both of the rolls 33a and 33b, and the support 33 is tensioned by this and used in a state in which it is stretched taut. do.

In the casting step, the cast film 35 formed by the dope casted on the support 33 is heated on the support 33, and the cast film 35 can be peeled from the support 33 by the peeling roll 34. Evaporate the solvent until In order to evaporate the solvent, there is a method of blowing air from the web side, a method of transferring heat with a liquid from the back side of the support 33, a method of transferring heat from the front and back by radiant heat, and the like, if used appropriately, alone or in combination. do.

<Peel-off step>

In the casting step, after drying and solidifying or cooling and solidifying the cast film 35 on the support 33 until it has a film strength capable of being peeled off, in the peeling step, the peeling roll 34 is applied while the cast film 35 is self-supporting. ) is peeled off by

In addition, it is preferable that the residual solvent amount of the cast film 35 on the support body 33 at the time of peeling is in the range of 50 to 120% by mass depending on the strength and weakness of the drying conditions, the length of the support body 33, and the like. In the case of peeling when the amount of residual solvent is greater, if the flexible film 35 is too soft, flatness is impaired during peeling, and wrinkles and vertical stripes due to peeling tension are likely to occur. The amount of residual solvent in is determined. In addition, the residual solvent amount is defined by the following formula.

Residual solvent amount (% by mass) = (mass of web before heat treatment - mass of web after heat treatment) / (mass of web after heat treatment) × 100

Here, heat treatment at the time of measuring the amount of residual solvent means performing heat treatment at 115 degreeC for 1 hour.

<First drying step>

The cast film 35 peeled from the support 33 is dried in the drying device 36 . Inside the drying apparatus 36, the cast film 35 is conveyed with the some conveyance roll arrange|positioned in the zigzag shape seen from the side, and the cast film 35 is dried in the meantime. The drying method in the drying device 36 is not particularly limited, and the cast film 35 is generally dried using hot air, infrared rays, heating rolls, microwaves, or the like. A method of drying the cast film 35 with hot air is preferred in terms of simplicity. In addition, the 1st drying process should just be performed as needed.

<Stretching process>

In the stretching step, the cast film 35 dried in the drying device 36 is stretched by the tenter 37 . The stretching direction at this time is either a film conveyance direction (MD direction; Machine Direction), a transverse direction perpendicular to the conveyance direction within the film plane (TD direction; Transverse Direction), or both of these directions. In the stretching step, a tenter method in which both edge portions of the cast film 35 are fixed with clips or the like and then stretched is preferable in order to improve the flatness and dimensional stability of the film. In the tenter 37, drying may be performed in addition to stretching.

<2nd drying process>

The cast film 35 stretched by the tenter 37 is dried in the drying device 38. Inside the drying apparatus 38, the cast film 35 is conveyed with the some conveyance roll arrange|positioned in a zigzag shape as seen from the side, and the cast film 35 is dried in the meantime. The drying method in the drying device 38 is not particularly limited, and the cast film 35 is generally dried using hot air, infrared rays, heating rolls, microwaves, or the like. A method of drying the cast film 35 with hot air is preferred in terms of simplicity.

After the cast film 35 is dried in the drying device 38, it is conveyed toward the winding device 41 as the optical film F.

<Cutting process, embossing process>

Between the drying apparatus 38 and the winding apparatus 41, the cutting part 39 and the embossing process part 40 are arrange|positioned in this order. In the cutting part 39, the cutting process of cutting both ends of the width direction with a slitter is implemented, conveying the optical film F formed into a film. In the optical film F, the portion remaining after cutting both ends constitutes a product portion to be a film product. On the other hand, the part cut from the optical film F is collected by the chute and reused again as part of the raw material for forming a film.

After the cutting step, the embossing process (knurling process) is given to the both ends of the width direction of the optical film F by the embossing process part 40. Embossing is performed by pressing a heated embossing roller against both ends of the optical film F. Fine irregularities are formed on the surface of the embossing roller, and by pressing the embossing roller against both ends of the optical film F, the irregularities are formed on the both ends. By such an embossing process, winding shift|offset|difference and blocking (sticking of films) in the next winding-up process can be suppressed as much as possible.

<Winding process>

Finally, the optical film F on which the embossing process has been completed is wound up by the winding device 41 to obtain an original winding (film roll) of the optical film F. That is, at a winding-up process, a film roll is manufactured by winding up around a winding core, conveying optical film F. As for the winding method of the optical film F, a generally used winder may be used, and there are methods for controlling the tension such as constant torque method, constant tension method, taper tension method, and program tension control method in which the internal stress is constant. , you can use them separately. The winding length of the optical film (F) is preferably from 1000 to 7200 m. In addition, it is preferable that the width|variety at that time is 1000-3200 mm width, and the film thickness should just adjust suitably in the range of 10-150 micrometers.

Example

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

≪Example 1≫

<Production of protective film P-1>

(Preparation of dope)

The following composition was put into a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore diameter of 34 µm and a sintered metal filter having an average pore diameter of 10 µm to prepare a cycloolefin polymer solution.

<Dope composition>

Cycloolefin polymer (“Aton” (registered trademark) manufactured by JSR) 150 parts by mass

380 parts by mass of dichloromethane

Next, the following composition containing the cycloolefin polymer solution prepared above was introduced into a disperser to prepare a fine particle dispersion.

<fine particle dispersion>

Fine particles (Aerosil R812: Nippon Aerosil Co., Ltd., primary average particle diameter: 7 nm, apparent specific gravity 50 g/L) 4 parts by mass

76 parts by mass of dichloromethane

10 parts by mass of cycloolefin polymer solution

Then, 100 parts by mass of the cycloolefin polymer solution and 0.75 parts by mass of the fine particle dispersion were mixed to prepare dope for film forming.

(Production of protective film)

Subsequently, the dope for film forming prepared above was uniformly cast on a stainless belt support body at a temperature of 31°C and a width of 1800 mm using an endless belt casting apparatus. The temperature of the stainless belt support body was controlled at 28 degreeC.

On the stainless belt support body, the solvent was evaporated until the amount of residual solvent in the casted (cast) film became 30% by mass. Then, the cast film (web) was peeled from the stainless belt support body at a peeling tension of 128 N/m. While drying the peeled web, it was stretched at a draw ratio of 20% (1.20 times) in the longitudinal direction by conveying tension, then conveyed to a tenter stretching device, and conveyed in a tenter at a draw ratio of 40% (1.40 times) in the width direction. . At this time, the drying conditions from peeling to tenter were adjusted so that the amount of residual solvent at the time of extending|stretching might be 5 mass %. In addition, the temperature of the tenter stretching device was set to 135°C, and the stretching speed was set to 200%/min.

Next, the web (film) after extending|stretching was introduce|transduced into the drying apparatus, and drying was complete|finished, conveying it with many rollers in the drying apparatus. Then, after slitting both ends of the obtained film in the width direction, embossing was performed and the protective film P-1 whose dry film thickness is 60 micrometers was produced.

<Production of base film F-1>

The dope used in the production of the protective film P-1 described above was cast on a stainless belt support. And the solvent was evaporated on the stainless belt support body until the amount of residual solvent in the cast|flow_spreaded (cast) film became 30 mass %. Next, the cast film (web) was peeled from the stainless belt support body at a peeling tension of 128 N/m. The peeled web was introduced into a drying zone, and drying was terminated while being conveyed by a large number of rollers. Then, while applying heat at 160°C to the web, it is stretched by 5% in the width direction using a tenter, and after slitting both ends in the width direction of the obtained film, embossing is performed, and a substrate having a dry film thickness of 18 μm Film F-1 was produced.

<Production of laminated film L-1>

(Manufacture of adhesive S-1)

By normal solution polymerization, an acrylic polymer with a weight average molecular weight of 600,000 was obtained at butyl acrylate/acrylic acid = 100/6 (weight ratio). To 100 parts by weight of this acrylic polymer, 6 parts by weight of an epoxy crosslinking agent (trade name "Tetrad C (registered trademark)" manufactured by Mitsubishi Gas Chemical) was added to prepare an acrylic adhesive.

(Manufacture of laminated film)

On the release-treated surface of the PET film subjected to the release treatment, the adhesive S-1 obtained in the above manner was applied and heated at 120°C for 60 seconds to form a pressure-sensitive adhesive layer having a thickness of 20 µm. Next, the PET film was bonded to the protective film P-1 produced above through the pressure-sensitive adhesive layer. Then, the PET film was peeled, and the adhesive layer formation protective film P-1 in which the adhesive layer was formed in one side of protective film P-1 was produced.

Next, the adhesive layer formation protective film P-1 and the base film F-1 prepared above were bonded together through the adhesive layer to prepare laminated film L-1.

<Production of transparent conductive film M-1>

(Formation of Transparent Conductive Layer A)

After the method using the polyol described in Y. Sun, B. Gates, B. Mayers, & Y. Xia, "Crystalline silver nanowires by soft solution processing", Nano letters, (2002), 2(2) 165 to 168, In the presence of polyvinylpyrrolidone (PVP), silver nanowires were obtained by dissolving silver sulfate in ethylene glycol and reducing it. That is, in this embodiment, silver nanowires synthesized by a modified polyol method described in US Provisional Application No. 60/815,627 (Cambrios Technologies Corporation) were used.

(Manufacture of laminate with transparent conductive layer)

A silver nanowire water dispersion composition containing 0.5% w/v of the silver nanowires (short axis diameter of about 70 nm to 80 nm, aspect ratio of 100 or more) synthesized by the above method in an aqueous medium (Cambrios Technologies Corporation ClearOhm™, Ink- A AQ) was applied onto the surface of the base film F-1 of the laminated film L-1 using a slot die coater so that the film thickness after drying was 1.5 µm, and dried. After that, a pressure treatment was performed at a pressure of 2000 kN/m ² , a transparent conductive layer A was formed on the base film F-1, and a laminate with a transparent conductive layer was obtained. After that, the laminate with a transparent conductive layer was wound into a roll shape.

(Peel off of protective film)

The protective film P-1 was peeled together with the adhesive S-1, unwinding and conveying the roll-shaped transparent conductive layer-forming laminate prepared above. Thus, a transparent conductive film M-1 in which the transparent conductive layer A was supported by the base film F-1 was obtained. Finally, the obtained transparent conductive film M-1 was wound up in a roll shape.

«Examples 2 to 7, Comparative Examples 1 to 8»

In the amount of residual solvent, film thickness, and tenter when the web is peeled from the support during production of the base film and the protective film so that the thermal contraction rate A of the base film and the thermal contraction rate B of the protective film are the values shown in Table 1 Substrate films F-2 to F-10 and protective films P-2 to P-8 were produced in the same manner as in Example 1, except that the stretching ratio and stretching temperature in the longitudinal and transverse directions were adjusted. Then, the base films F-1 to F-10 and the protective films P-1 to P-8 are appropriately selected so as to be the combination described in Table 1, and laminated through the pressure-sensitive adhesive S-1 or the pressure-sensitive adhesive S-2, and the laminated film L-2 to L-15 were obtained. In addition, the preparation method of adhesive S-2 is mentioned later.

Then, in the same manner as in Example 1, a transparent conductive layer A was formed on the base film to produce a roll-shaped laminate with a transparent conductive layer. Then, transparent conductive films M-2 to M15 were obtained by unwinding the roll-shaped transparent conductive layer-forming laminate and peeling the protective film together with the pressure-sensitive adhesive. Finally, the obtained transparent conductive films M-2 to M-15 were rolled up.

(Manufacture of adhesive S-2)

Adhesive S-2 was prepared in the same manner as in the preparation of adhesive S-1, except that the epoxy-based crosslinking agent (trade name "Tetrad C (registered trademark)" manufactured by Mitsubishi Gas Chemical Co., Ltd.) was changed to 4 parts by weight.

≪Evaluation≫

(1) Measurement of thickness

The thickness of the protective film and the base film was measured using a micro gauge type thickness meter (manufactured by Mitutoyo Corporation).

(2) Thermal shrinkage in the width direction

The thermal contraction rates of the base film and the protective film in the width direction were measured as follows. Specifically, the base film and the protective film are cut into 100 mm in the width direction and 100 mm in the length direction (the cut film is called a "test piece"), and cross marks (X marks) are formed at two points at both ends in the width direction, , The length (mm) before heating between the two central points of the cross mark was measured with a CNC coordinate measuring machine (LEGEX774 manufactured by Mitutoyo Co., Ltd.). After that, the test piece was put into an oven and subjected to heat treatment (140°C, 90 minutes). After cooling at room temperature for 1 hour, the length (mm) after heating between two points was measured again with a CNC three-dimensional measuring machine, and the thermal contraction rate in the width direction was determined by substituting the measured value into the following formula.

Thermal shrinkage rate (%) = [{Length before heating (mm) - Length after heating (mm)}/Length before heating (mm)] × 100

(3) Deformation during peeling

The deformation of the transparent conductive film at the time of peeling off the protective film on which the pressure-sensitive adhesive layer was formed was evaluated based on the following evaluation criteria.

≪Evaluation Criteria≫

○: No deformation occurred in the transparent conductive film during peeling of the protective film, and no deformation occurred after winding up.

(triangle|delta): The transparent conductive film was deformed at the time of peeling of the protective film, but the deformity did not occur after winding up.

x: Strain occurred in the transparent conductive film at the time of peeling of the protective film, and the strain remained after winding up.

(4) energization test

The prepared transparent conductive film is cut into 100 mm in the width direction and 100 mm in the length direction (the cut film is referred to as a “test piece”), and heat treatment is performed at 120° C. for 40 minutes on the test piece in a hot air circulation oven. did Then, the surface resistance of the test piece was measured by the 4-terminal method according to JIS K7194 at 9 locations, and evaluated based on the following evaluation criteria.

≪Evaluation Criteria≫

○: The surface resistance was 110 Ω/□ or more at 0 out of 9 places.

(triangle|delta): The surface resistance was 110 Ω/□ or more in 1 place out of 9 places.

x: The surface resistance was 110 Ω/square or more at 2 or more out of 9 places.

(5) Bending current durability

The produced transparent conductive film is cut into 200 mm in width direction and 100 mm in length direction (the cut film is referred to as “test piece”), and heat treatment is performed on the test piece at 120° C. for 40 minutes in a hot air circulation oven. did Thereafter, the test piece was bent and fixed by 180 degrees in the width direction (with the longitudinal direction as the bending axis) between two glass plates so as to have a bending diameter of 3 mmΦ, and left to stand for 500 hours in an environment of 60°C and 90% RH. Thereafter, the surface resistance of the bent portion of the test piece was measured by the 4-terminal method according to JIS K7194, and evaluated based on the following evaluation criteria.

≪Evaluation Criteria≫

○: The surface resistance was 110 Ω/□ or less.

△: The surface resistance was greater than 110 Ω/□ and less than 200 Ω/□.

x: The surface resistance was larger than 200 Ω/□.

Table 1 shows the evaluation results for Examples 1 to 7 and Comparative Examples 1 to 8.

From Table 1, in Comparative Examples 5 and 6, the bending current durability is poor (x). In Comparative Example 6, the thickness of the base film was 3 μm, and since the base film was too thin, the base film cracked when bending and conveying the transparent conductive film in which the transparent conductive layer was formed on the base film with a roll. It is easy, and as a result, it is considered that the transparent conductive layer is broken and the conduction defect is generated. Further, in Comparative Example 5, the thickness of the base film was 50 µm, and since the base film was too thick, the transparent conductive layer on the base film stretched in the circumferential direction of the roll during bending and conveying of the transparent conductive film by the roll. This is considered to be caused by failure of the current supply.

In contrast, in Examples 1 to 7, the film thickness of the base film is 5 μm or more and 40 μm or less, and the bending resistance of the transparent conductive film is good (○ or △). From this, in Examples 1 to 7, breakage of the transparent conductive layer at the time of bending and conveying by the roll of the transparent conductive film can be suppressed, and a thin transparent conductive film can be produced with high productivity by roll-to-roll. can be said to be possible.

In addition, in Comparative Examples 3 and 4, energization failure occurred. In Comparative Example 3, the thermal shrinkage rate A of the base film was as large as 0.25%, and since the thermal shrinkage of the base film during heat processing of the transparent conductive layer was too large, the transparent conductive layer on the base film could not follow the shrinkage of the base film. It is thought that there is no current, and it is broken, and an energization defect has occurred. In Comparative Example 4, since the thermal contraction rate A of the base film is as small as 0.001%, the shrinkage stress generated in the base film during heat processing of the transparent conductive layer is small, and sufficient residual stress cannot be obtained. For this reason, it is considered that it is difficult to uniformly peel the protective film from the base film, and at the time of peeling, the base film is partially pulled toward the protective film side, and the transparent conductive layer 17 is broken, resulting in poor conduction. .

On the other hand, in Examples 1-7, the heat shrinkage rate A of the width direction of a base film is 0.01 % or more and 0.20 % or less, and favorable results ((circle) or (triangle|delta)) were obtained in the electrification test. From this, it can be said that in Examples 1 to 7, the transparent conductive film can be manufactured while suppressing breakage of the transparent conductive layer at the time of heat processing of the transparent conductive layer and peeling of the protective film.

In Comparative Examples 1 and 2, deformation occurred in the transparent conductive film during peeling of the protective film. In Comparative Example 1, A/B is as large as 0.60, and since the difference in thermal contraction rate between the base film and the protective film is small, it becomes difficult to peel the protective film from the base film using the difference in thermal shrinkage amount. For this reason, it is considered that as a result of peeling the protective film with a high peeling force, the transparent conductive film was pulled toward the protective film side and deformed. Moreover, in Comparative Example 2, A/B is as small as 0.01, and the thermal contraction rate B of the protective film is large with respect to the thermal contraction rate A of the base film. For this reason, during the heat processing of the transparent conductive layer, the protective film greatly thermally shrinks and peels off at the ends of the protective film, making it difficult to uniformly peel the protective film from the base film in the width direction at the time of peeling. As a result, it is considered that the base film was wrinkled at the time of peeling of the protective film, and the transparent conductive film was deformed.

Further, in Comparative Example 7, in order to facilitate peeling of the protective film, the protective film and the base film were laminated via the adhesive S-2, which has a weaker adhesive force than the adhesive S-1, to prepare a laminate with a transparent conductive layer, there is. In this configuration, since the adhesive force of the pressure-sensitive adhesive S-2 is weak, the protective film is naturally peeled off during transport of the laminate with a transparent conductive layer, the peeled protective film is rolled up by the transport roll and the remaining film is broken, so various evaluations have been conducted. could not be carried out

In Comparative Example 8, the thermal contraction rate A of the base film and the thermal shrinkage rate B of the protective film are set equal to Example 3 of Patent Document 2 described above. In this configuration, since the value of A/B is too large (because the value of A/B is close to 1), the protective film cannot be peeled off from the base film using the difference in thermal shrinkage amount, and the protective film has a high peeling force. As a result of the peeling, it is considered that the transparent conductive film was deformed.

«Examples 8 to 11»

The amount of residual solvent, film thickness, stretching ratio in the longitudinal direction and width direction in the tenter, and stretching temperature at the time of peeling the web from the support during production of the protective film so that the film thickness of the protective film becomes the value shown in Table 2 Protective films P-9 to P-12 were produced in the same manner as in Example 1, except that . And the base film F-1 was laminated|stacked on each protective film P-9-P-12 via the adhesive S-1, the laminated film L-16-L-19 was produced, and laminated|multilayer film L-16-L- After forming the transparent conductive layer A on No. 19, protective films P-9 to P-12 were peeled off to produce transparent conductive films M-16 to M-19.

≪Evaluation≫

(6) Wrinkles during transport of the laminated film

In the process of forming a transparent conductive film, the conveyance state of the laminated film was observed and evaluated based on the following evaluation criteria.

≪Evaluation Criteria≫

(double-circle): Wrinkles do not occur during conveyance of the laminated film.

○: Weak wrinkles occur during transportation of the laminated film, but the wrinkles disappear when the laminated film is wound up.

x: Weak wrinkles occur during conveyance of the laminated film, and wrinkles remain even after winding up the laminated film.

Table 2 shows the evaluation results for Examples 8 to 11. For reference, Table 2 shows the results of evaluating wrinkles during transport of the laminated film according to the same evaluation criteria for Example 1 as well.

From Table 2, it can be said that when the film thickness of the protective film is 40 µm or more and 100 µm or less, and is thicker than the film thickness of the base film, it is possible to effectively reduce the occurrence of wrinkles during conveyance of the laminated film. This is because shrinkage force due to the heat of the protective film can be appropriately generated in the above film thickness range of the protective film, so during transportation of the transparent conductive layer during heat processing, it is affected by the heat shrinkage of the protective film and wrinkles in the base film. This is thought to be because the occurrence of this can be further reduced.

«Example 12»

A transparent conductive film M-20 was produced in the same manner as in Example 1 except that the transparent conductive layer A was replaced with the transparent conductive layer B. More specifically, it is as follows.

<Production of transparent conductive film M-20>

(Preparation of resin composition for forming cured resin layer)

100 parts by weight of an ultraviolet curable resin composition (trade name "UNIDIC (registered trademark) RS29-120" manufactured by DIC Corporation) and 0.2 part by weight of acrylic spherical particles having a modal particle diameter of 1.9 µm (trade name "MX-180TA" manufactured by Soken Chemical Co., Ltd.) A curable resin composition containing spherical particles was prepared.

(Formation of Cured Resin Layer)

The prepared curable resin composition containing the spherical particles was applied to the surface of the base film F-1 of the laminated film L-1 to form a coating layer. Next, the coating layer was irradiated with ultraviolet rays from the side where the coating layer was formed to form a cured resin layer having a thickness of 1.0 μm.

(Formation of Transparent Conductive Layer B)

The laminated film L-1 on which the cured resin layer was formed was put into a winding-type sputtering device, and an amorphous indium-tin oxide layer having a thickness of 27 nm (composition: SnO ₂ 10 wt%; hereinafter also referred to as ITO) was formed on the surface of the cured resin layer. ) was formed to produce a laminate with a transparent conductive layer. More specifically, after pretreatment of the surface of the cured resin layer by glow discharge, the laminated film L-1 having the cured resin layer is disposed in a vacuum chamber of a magnetron type sputtering apparatus in opposition to an ITO target, and the air is replaced with argon. Sputter deposition was performed at 1 m/min at an applied voltage of DC 9 kW in an environment of a vacuum degree of 2×10 ^-3 Torr obtained by complete replacement. Next, with reference to paragraphs [0046] to [0050] of Japanese Unexamined Patent Publication No. 11-243296, an ITO conductive film is formed as a transparent conductive layer B on the surface of the cured resin layer formed on the base film F-1, After obtaining the layered product with a transparent conductive layer, the protective film P-1 with adhesive S-1 was peeled while conveying, and the transparent conductive film M-20 was produced. And the produced transparent conductive film M-20 was wound up in roll shape.

≪Evaluation≫

(7) Repeated bending durability

The produced transparent conductive film M-20 was put into a hot air circulation type oven, and heat treatment was performed at 120°C for 40 minutes. After that, using a durability tester (manufactured by Yuasa System Equipment, product name "Flat body unloaded U-shaped stretch tester"), minimum bending diameter: 3 mmφ, speed: 30 times/minute, number of bending times: 50,000 times, test temperature : On conditions of 23 degreeC, it bent repeatedly with the transparent conductive layer inward. Then, the surface resistance of the sample was measured by the 4-terminal method according to JIS K7194, and evaluated based on the following evaluation criteria. In addition, the rate of change of the surface resistance value was calculated from the following formula.

Change rate of surface resistance value (%) = {(Surface resistance value after bending 50,000 times - Surface resistance value before bending) / (Surface resistance value before bending)} × 100

≪Evaluation Criteria≫

(double-circle): The rate of change of the surface resistance value was 10% or more and less than 20%.

○: The change rate of the surface resistance value was 20% or more and less than 30%.

x: The change rate of the surface resistance value was 30% or more.

The evaluation results for Example 12 are shown in Table 3. For comparison, Table 3 shows the results of evaluation of repeated bending durability on the same evaluation criteria for Example 1 as well.

In Example 1, a conductive film containing silver nanowires is used as the transparent conductive layer A, whereas in Example 12, an ITO conductive film is used as the transparent conductive layer B. It turns out that the conductive film containing the silver nanowires has excellent repeated bending durability compared to the ITO conductive film and is less likely to break. From this point of view, it can be said that it is preferable to use a conductive film containing silver nanowires as the transparent conductive layer.

[supplement]

From the above, the laminated film demonstrated in this embodiment can be expressed as follows.

1. As a laminated film for supporting a transparent conductive layer of a transparent conductive film,

A base film for supporting the transparent conductive layer;

It has a protective film that supports the base film through an adhesive layer,

The base film and the protective film each include a cycloolefin resin,

The film thickness of the base film is 5 μm or more and 40 μm or less,

The heat shrinkage rate A (%) of the base film in the width direction at the time of heating at 140 ° C. for 90 minutes is 0.01% or more and 0.20% or less,

When the thermal contraction rate of the protective film in the width direction at the time of heating at 140 ° C. for 90 minutes is B (%),

0.02 ≤ A/B ≤ 0.50

Laminated film, characterized in that.

2. The layered film according to 1 above, wherein the protective film has a film thickness of 40 μm or more and 100 μm or less, and is thicker than the film thickness of the base film.

3. The laminated film according to 1 or 2 above, which is for supporting a conductive film containing metal nanowires as the transparent conductive layer.

In addition, the laminate with a transparent conductive layer described in this embodiment can be expressed as follows.

4. A laminate with a transparent conductive layer comprising a transparent conductive layer positioned on the base film of the laminate film according to any one of 1 to 3 above.

In addition, the manufacturing method of the transparent conductive film demonstrated in this embodiment can be expressed as follows.

5. A step of forming the transparent conductive layer on the base film of the laminated film according to any one of 1 to 3 to obtain a laminate with a transparent conductive layer, and winding the laminate with a transparent conductive layer into a roll shape;

and a step of unwinding the transparent conductive layer forming laminate, peeling the protective film from the transparent conductive layer forming laminate, and winding the transparent conductive film having the transparent conductive layer on the base film in a roll shape. Method for producing a transparent conductive film to be.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and may be expanded or modified without departing from the scope of the present invention.

The laminated film for support of the transparent conductive layer of the present invention can be used, for example, for production of a transparent conductive film used in a touch sensor panel of a touch panel display device.

10: laminate with transparent conductive layer
12: transparent conductive film
14: protective film
15: adhesive layer
16: base film
17: transparent conductive layer
20: laminated film

Claims (3)

As a laminated film for supporting a transparent conductive layer of a transparent conductive film,
A base film for supporting the transparent conductive layer;
It has a protective film that supports the base film through an adhesive layer,
The base film and the protective film each include a cycloolefin resin,
The film thickness of the base film is 5 μm or more and 40 μm or less,
The heat shrinkage rate A (%) of the base film in the width direction at the time of heating at 140 ° C. for 90 minutes is 0.01% or more and 0.20% or less,
When the thermal contraction rate of the protective film in the width direction at the time of heating at 140 ° C. for 90 minutes is B (%),
0.02 ≤ A/B ≤ 0.50
Phosphorus, laminated film. According to claim 1,
The film thickness of the said protective film is 40 micrometers or more and 100 micrometers or less, and is thicker than the film thickness of the said base film. According to claim 1 or 2,
A laminated film for supporting a conductive film containing metal nanowires as the transparent conductive layer.

Images