KR20150139682A - Base film for metal mesh - Google Patents

Abstract

Provided in the present invention is a base material film for a metal mesh, which is a laminate film comprising a base film made with a polymer, and a primer coating layer formed on at least one side of the base film, wherein the coating layer is formed by coating a curing resin composition including an acrylic resin on the base film, and curing the same, and has refractive ratio of 1.40 to 1.51. The base material film for a metal mesh has a thin coating layer, while having not only chemical resistance and adhesion to a metallic material, but also excellent permeability to a beam.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a base film for metal meshes,

More particularly, the present invention relates to a base film for a metal mesh having a coating layer formed of a thin film of 300 nm or less and having an excellent adhesion to a metal material and an improved total light transmittance.

The demand for medium and large sized touch panels including tablets is rapidly increasing. In such a large and medium sized touch panel, a GFF type touch panel using two ITO films on the bottom of the cover glass has been mainly used. However, indium (Indium), the main raw material of ITO film, has recently experienced a sharp price increase due to the restriction of indium production by the Chinese government. In the domestic and overseas touch panel industry, where almost all ITO film is imported from Nitto Denko of Japan, the company is struggling to secure price competitiveness of large area touch panels.

As a result, ITO film, which accounts for about 40% of touch screen cost, has been replaced by metal mesh, silver nanowire, carbon nanotube (CNT), and graphene There is an active attempt to

Among the substitutes, metal meshes are considered as the most likely candidates (see KR2010-0048931A, KR2010-0089880A, KR2012-0138287A, KR2013-0008876A, etc.). Recently, metal-meshed films are attracting more attention as ITO substitute films because they are technically advantageous for the implementation of middle- to large-sized touch panels. As the size of the touch panel is accelerated and it is expected to be applied to TV, the metal mesh method is getting more attention. It is difficult to use ITO film due to the problem of uniformity in large-sized displays over 20 inches, and instead of ITO film, ITO glass is mainly used, but a costly alternative film is being developed in various ways.

Metal mesh is advantageous in that it is easier to apply touch to a large screen because it is less costly than current ITO film and it has low resistance value due to its metal characteristics. On the other hand, it has a lower light transmittance than ITO, The disadvantage is that the touch pattern is faint. In order to overcome such disadvantages, it is important to reduce the line width. However, if the line width is reduced to 3 μm, it can be applied to tablet PCs or notebook PCs of 15 inches or less. Therefore, it is necessary to fabricate an electrode film on a transparent substrate of a glass or plastic film by finely finishing the metal in an orthogonal form so as to be invisible to a few micrometers.

In order to form a fine pattern on the film, the adhesive force between the film surface and the metal used as the substrate must be very good. In addition, during the process for forming the metal pattern, The chemical resistance characteristic that no change is required is also required. PET, which is used as an existing base film, does not satisfy the above characteristics at the same time.

An object of the present invention is to provide a base film for a metal mesh having a coating layer formed of a thin film of 300 nm or less while exhibiting excellent chemical resistance and adhesiveness to a metal material as well as improved total light transmittance.

The metal film base film of the present invention is a laminated film comprising a base film of a polymeric material and a primer coating layer formed on at least one side of the base film, wherein the coating layer comprises a curable resin composition comprising an acrylic resin, And is cured, and has a refractive index of 1.40 to 1.51.

The base metal film for metal mesh preferably has a total light transmittance of 92.5% or more and a haze value of 1% or less as measured by the ASTM D-1003 method.

The thickness of the coating layer is preferably 50 to 300 nm.

It is preferable that the curable resin composition comprises 10 to 500 parts by weight of inorganic particles for adjusting refractive index with respect to 100 parts by weight of an acrylic resin.

The acrylic resin may be a (meth) acrylate monomer, a urethane (meth) acrylate, an epoxy (meth) acrylate, a polyester Fluorene (meth) acrylate, and the like.

The curable resin composition is preferably thermosetting.

The inorganic particles are preferably hollow or porous fine particles.

The inorganic particles are preferably silica having an average primary particle size of 10 to 200 nm as measured by the BET method.

Another advantage of the base film for metal mesh according to the present invention is that it has excellent adhesion to a metal mesh laminated on a base film.

Another advantage of the base film for metal mesh according to the present invention is that the refractive index of the primer coating layer is adjusted and the transmittance of the base film for metal mesh including the same is high.

1 is a schematic cross-sectional view of a base film for metal mesh (10, 20) according to the present invention.

Hereinafter, the metal base film for metal mesh of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view of a base film for metal mesh (10, 20) according to the present invention. 1, a metal mesh base film 10, 20 of the present invention includes a base film 11 made of a polymer material and a laminated film 12 having a primer coating layer 12 formed on one surface of the base film 11 1a) or a laminated film (FIG. 1B) in which primer coating layers 22, 23 are formed on both sides of the base film 21. The base film for metal mesh (10, 20) according to the present invention is characterized in that the primer coating layer is formed by applying a curable resin composition comprising an acrylic resin on a base film and then curing, and has a refractive index of 1.3 to 1.5 .

1. Base film (11, 21)

In the base films 10 and 20, the base films 11 and 21 are excellent in mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, optical characteristics, and the like, have. Any film having sufficient mechanical and thermal stability and high visible light transmittance can be used without limitation. In particular, in order to be used as a member for an image display device, the light transmittance at a wavelength of 400 to 800 nm is preferably 70% or more, more preferably 80% or more, and the haze value is preferably 5% Preferably 3% or less.

The base film may typically be a polymeric polymer film such as polycarbonate, polyolefin, polyvinyl resin, or polyester.

Preferably, a synthetic linear polyester film is used, and a polymer film having a high transmittance such as a polyethylene terephthalate (PET) film or a polyethylene naphthalate (PEN) film having both light transmittance and thermal stability is used.

The thickness of the base film is not particularly limited, and a typical thickness is in the range of 5 to 500 mu m, preferably 20 to 250 mu m.

The polymer polymer film used in the base film may be chemically treated by corona treatment, plasma treatment or the like for the purpose of improving the adhesion with the primer layer or the like, thereby improving the surface tension, , A partially hydrolyzed copolymer, a highly polar primer treatment, or the like, or subjected to roughing treatment, stretching or heat treatment, water repellent treatment for thermal stability, or containing a small amount of fine particles or filler It can be done. On the other hand, the base film may be obtained by bonding two or more films by a known method.

2. Primer coating layers (12, 22, 23)

In the base film for metal mesh according to the present invention, the primer coating layer is formed by applying a curable resin composition containing an acrylic resin onto a base film and then thermally curing and / or photo-curing. In the present invention, the refractive index of the coating layer is 1.3 to 1.6.

2.1. Curable resin

The curable resin composition includes a curable acrylic resin and an inorganic particle for controlling refractive index.

The acrylic resin for forming the primer coating layer is a composition containing a compound having at least one (meth) acryloyl group in the molecule. Examples of the compound having a (meth) acryloyl group include (meth) acrylate monomers, urethane (meth) acrylates, epoxy (meth) acrylates, polyester (meth) acrylates, polyether (Meth) acrylate such as polycarbonate (meth) acrylate and fluorene (meth) acrylate. These may be used singly or in combination of two or more kinds. At least one of an acrylate monomer, a urethane acrylate and an epoxy acrylate is preferably used from the viewpoint of promptly accelerating the curing reaction.

(Meth) acrylate monomer, an urethane (meth) acrylate, an epoxy (meth) acrylate, a polyester (meth) acrylate and the like are used in order to adjust the physical properties in consideration of the improvement of the curability, (Meth) acrylate oligomer such as polyether (meth) acrylate, polycarbonate (meth) acrylate and the like may optionally be added to the curable resin composition.

If necessary, a polyfunctional resin having three or more functional groups, such as trimethylol propane triacrylate, trimethylol propane trimethacrylate, ditrimethylol propane tetraacrylate, ditrimethylol propyl acrylate, Pentaerythritol tetramethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, pentaerythritol tetramethacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, A (meth) acrylate having two or more acryloyl groups such as acrylate as a monomer component may be further added.

The above-mentioned curable resin composition may contain other photo-curable oligomers or monomers, photoinitiators, sensitizers, crosslinking agents, ultraviolet absorbers, polymerization inhibitors, fillers, thermoplastic resins and the like as components other than the photo- May be contained in a range that does not interfere with physical properties such as water absorption. In particular, when ultraviolet irradiation is applied as an active energy ray, a photoinitiator is essential. As the photoinitiator, known ones such as benzoin-based, acetophenone-based, thioxanthone-based, phosphine oxide-based, and peroxide-based ones can be used.

Commercially available acrylic resins can be used in a suitable solvent, for example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, aromatic compounds such as toluene and xylene, Hexanone, isopropanol, and the like. The amount of these solvents to be used is not particularly limited, and usually 0 to 300 parts by weight based on 100 parts by weight of the total solid content of the curable resin composition can be purchased and used.

2.2. Inorganic particles for controlling refractive index

The refractive index-controlling inorganic particles contained in the curable resin composition function to improve the transmittance of the base film for metal mesh by lowering the reflectance of the base film. The reflectance of the base film serves as a factor for lowering the light transmittance. Therefore, when the refractive index of the primer coating layer is adjusted to lower the reflectance of the surface of the base film, the transmittance of the metal mesh base film can be improved by a lower reflectance.

The present invention is characterized in that means for adding refractive index controlling inorganic particles to a resin composition for forming a coating layer for controlling the refractive index of the primer coating layer is adopted. The inorganic particles used for this purpose include, for example, silica particles , Alumina particles, metal powders, and any inorganic particles capable of controlling the refractive index difference between the base film and air.

Preferably, hollow or porous inorganic particles are used, and hollow or porous silica fine particles are more preferably used. The silica fine particles may be, for example, dry silica, wet silica, silica fine particles dispersed in a colloidal form, and the like. The fine silica particles may be surface-treated by a known method. As the surface treatment method, there are a physical surface treatment such as a plasma discharge treatment and a corona discharge treatment, and a chemical surface treatment using a coupling agent, but chemical treatment is preferably used.

The silica may be spherical or water-phase, and preferably has an average primary particle diameter (spherical equivalent diameter: BET method) of 10 to 200 nm, more preferably 20 to 80 nm. If the range of the average particle size is satisfied, the transparency of the resulting coating film (resin layer) is not lowered, and the surface hardness can be improved. On the other hand, it is also possible to mix particles of two or more components having different average particle diameters so that the average of the total is included in the above-mentioned range.

It is preferable that the above-mentioned inorganic particles are contained in a proportion of 10 to 500 parts by weight based on 100 parts by weight of the acrylic resin. The refractive index of the acrylic resin for hard coating is usually about 1.52. If the content of the inorganic particles is less than 10 parts by weight, there is no effect of lowering the refractive index of the coating layer. Accordingly, the refractive index difference between the base film layer (for example, the refractive index of the polyethylene terephthalate film = 1.57-1.58) Was not found to be effective. On the other hand, if the amount exceeds 500 parts by weight, the effect of improving the permeability is rather reduced, and the surface roughness of the resin layer is increased due to particles excessively contained in excess of the proper amount (roughness), defects occur in the metal layer on the resin layer, There is a problem that the surface roughness is also increased and the quality is deteriorated.

On the other hand, the lower the refractive index of the coating layer, the better. However, according to the experiment of the inventors, when the acrylic resin is used as the curable resin, the lower limit of the refractive index of the primer coating layer, which is controlled by the addition of the inorganic particles (for example, the refractive index of silica to 1.40 and the refractive index of the hollow silica to 1.37) It is confirmed to be about 1.4.

2.3. Formation of primer coating layer

The composition containing the above-mentioned curable acrylic resin is diluted with an appropriate solvent and prepared as a coating solution, and then coated and cured on a base film to form a primer coating layer.

Examples of the organic solvent capable of dissolving the acrylic resin include ketones such as acetone, methyl ethyl ketone and cyclohexanone, methanol, ethanol, propanol, benzyl alcohol, and alcohol, glycol ether and ester. Some examples of the solvent include cyclohexanone, methyl ethyl ketone, benzyl alcohol, diethylene glycol alkyl ether, phenoxy propanol, propylene glycol methyl ether acetate, tetrahydrofuran, N-methylpyrrolidone, etc. Or a mixture of two or more of them may be used. If necessary, an aromatic or aliphatic hydrocarbon solvent such as toluene, xylene or hexane may be added as a diluent in order to improve the coating defects and adhesion to the base film. The amount of diluent should not exceed 40% of solvent.

The solid content in the coating liquid is preferably 0.1 to 20% by weight. When the solid content is 0.1% by weight or less, it is difficult to form a coating film by coating due to the dilute concentration. On the other hand, when the content of the solid content exceeds 20% by weight, it is not easy to uniformly cure, and there is a problem that blocking occurs during winding even if curing occurs.

The coating solution may optionally contain an antioxidant, a stabilizer, an additive for controlling adhesion to other layers, and the like.

The coating liquid is applied on a base film according to a known method such as gravure coating, microgravure coating, knife coating, bar coating, roll coating, spin coating and the like. On the other hand, the coating may be formed by an offline coating or an inline coating method depending on the timing.

The application of the coating solution is carried out by applying a primer solution on the base film at a coating amount of 0.01 to 10 g / m ² , drying and curing and forming a primer layer having a thickness of 50 to 300 nm. If the thickness of the primer layer is less than 50 nm, the chemical resistance of the primer layer is lowered. If the thickness exceeds 300 nm, the primer coating surface and the surfaces of the primer layer are wound at a constant pressure to cause blocking or hardening of the primer layer.

The curing of the primer coating layer may be performed by a method such as thermal curing, thermal curing or energy ray curing, alone or in combination.

The heat curing is performed, for example, by heating with a hot air drier at a temperature of 100 to 150 ° C for a time of 5 to 60 seconds to cure the coating layer simultaneously with drying. According to the thermosetting method as described above, there is an additional advantage that productivity can be improved because the curing speed is higher than that according to the photo-curing. On the other hand, the energy ray curing can be performed using, for example, an ultraviolet irradiation apparatus using a xenon lamp, a high-pressure mercury lamp, a metal halide lamp or the like, or an electron beam accelerator having an energy of 100 to 500 eV. Among them, according to the thermosetting method, there is an advantage that the hardening speed is higher than that in the case of the photo-curing, and the productivity can be improved.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited by these examples.

Example 1

Base film: A polyethylene terephthalate film having a thickness of 100 占 퐉 was used (XU46H, Toray Hi-tech Co., Ltd.).

2 parts by weight of a curing agent (product of ATSC, TKA-100) based on 100 parts by weight of an acrylate polymer resin (SAP-1500M40, product of ATSC Co., Ltd.) , And 10 parts by weight of silica particles (MIP40-EP manufactured by CENEFE Co., Ltd.) having a particle diameter of 30 nm were prepared.

Preparation of Base Film: The coating solution was applied to the base film at a coating amount of 0.01 to 10 g / m < ² > using a bar coater using a bar coater and cured at 130 DEG C for 30 seconds, To prepare a base film for metal mesh having a primer coating layer formed thereon.

Example 2

A metal mesh base film was prepared in the same manner as in Example 1, except that a coating liquid containing 50 parts by weight of silica particles was prepared in 100 parts by weight of the acrylate polymer resin.

Example 3

In the same manner as in Example 1 except that a coating solution containing 100 parts by weight of silica particles per 100 parts by weight of the acrylate polymer resin was prepared and the thickness of the primer coating layer was 100 nm, A film was prepared.

Example 4

In the same manner as in Example 1 except that a coating solution containing 200 parts by weight of silica particles per 100 parts by weight of the acrylate polymer resin was prepared and the thickness of the primer coating layer was 100 nm, A film was prepared.

Example 5

The procedure of Example 1 was repeated except that a coating liquid containing 300 parts by weight of silica particles per 100 parts by weight of the acrylate polymer resin was prepared and the thickness of the primer coating layer was 100 nm, A film was prepared.

Example 6

The procedure of Example 1 was repeated except that a coating liquid containing 300 parts by weight of silica particles per 100 parts by weight of the acrylate polymer resin was prepared and the thickness of the primer coating layer was 100 nm, A film was prepared.

Comparative Example 1

Only the base film on which no primer coating layer was formed was evaluated as a control.

Comparative Example 2

In Example 1, a metal mesh base film was prepared in the same manner as in Example 1, except that silica particles were not included in preparing the primer coating solution.

evaluation

(1) Optical characteristics (transmittance, haze)

The total light transmittance and haze measured by the ASTM D-1003 method were measured using a spectrophotometer (Model NDH5000, manufactured by Nippon Denshoku).

(2) Measurement of refractive index

A black tape was attached to the film surface opposite to the side on which the coated film was formed, and the absolute reflectance on the coating film side was measured using a reflection spectroscopic film thickness meter (" FE-3000 " manufactured by Otsuka The refractive index was measured.

(3) Chemical resistance

The chemical characteristics in the substrates prepared according to the above-mentioned Comparative Examples and Examples were examined. The chemical properties of the films were determined by SEM and UV-Vis, after immersing each sample in a 4% NaOH solution at room temperature (25 ° C). Min, and the value was measured at least 10 different points in each sample to improve reliability. As a result of the test, the time when the change in haze value measured according to ASTD D-1003 before and after the test was kept at 0.5% or less was observed without visual and physical changes as compared with before the test.

(4) Adhesion to metals

A 100 nm Cu-metal layer was formed on the primer coating layer using a sputtering machine. The adhesion to the metal layer was confirmed by a cross-cut evaluation according to ASTM D3002.

- 5B: No dropouts

- 4B: The falling side is within 5%

- 3B: The falling side is within 5 ~ 15%

- 2B: falling side within 15 ~ 35%

- 1B: falling side within 35 ~ 65%

Coating thickness
(nm) Particle content
(Parts by weight) Refractive index Transmittance
(%) Haze
(%) Chemical resistance
(4% NaOH) Metal
Adhesion Example 1 100 10 1.51 92.6 0.69 5min 4B Example 2 100 50 1.51 92.7 0.64 5min 4B Example 3 100 100 1.50 92.9 0.71 5min 4B Example 4 100 200 1.47 93.3 0.72 5min 4B to 5B Example 5 100 300 1.43 94.3 0.67 5min 4B to 5B Example 6 100 500 1.46 93.1 0.75 5min 4B Comparative Example 1 0 No additives 1.64 91.83 0.85 1 min 4B Comparative Example 2 100 No additives 1.52 92.1 0.65 5min 4B

It was confirmed through the examples that the silica particle content was 300% by weight as well as the excellent permeability characteristics as compared with the base film without the primer coating layer, as well as the chemical and metal adhesion properties important for metal mesh formation.

10.20. Base film for metal mesh
11. 21. Base film
12, 22, 23. Primer coating layer

Claims (11)

A laminated film comprising a base film made of a polymer material and a primer coating layer formed on at least one side of the base film,
Wherein the coating layer is formed by coating a curable resin composition containing an acrylic resin on a base film and then curing the composition and having a refractive index of 1.4 to 1.52. The base film for metal mesh according to claim 1, wherein the total light transmittance measured by the ASTM D-1003 method is 92.5% or more and the haze value is 1% or less. The base film for a metal mesh according to claim 1, wherein the coating layer has a thickness of 50 to 300 nm. The base film for a metal mesh according to claim 1, wherein the curable resin composition comprises 10 to 500 parts by weight of an inorganic particle for adjusting refractive index with respect to 100 parts by weight of an acrylic resin. The method of claim 1, wherein the acrylic resin is selected from the group consisting of (meth) acrylate monomers, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, polyether Wherein the resin is a resin obtained from at least one monomer selected from the group consisting of (meth) acrylate and fluorene (meth) acrylate. The metal mesh base film according to claim 1, wherein the curable resin composition is of a thermosetting type The base film for metal mesh according to claim 4, wherein the inorganic particles are hollow or porous fine particles. The base film for metal mesh according to claim 4, wherein the inorganic particles are silica having an average primary particle diameter of 10 to 200 nm as measured by the BET method. The base film for metal mesh according to claim 1, wherein a change in haze value measured according to ASTD D-1003 is 0.5% or less before and after immersion in a 4 wt% NaOH solution at room temperature for 5 minutes or longer. The adhesive sheet according to claim 1, characterized in that the adhesive force between the base film and the primer layer measured by the cross-cut evaluation method is 4B or more after the primer layer is formed on both surfaces of the substrate layer, By weight based on the total weight of the metal film. The base film for metal mesh according to claim 1, wherein the adhesion between the primer and the metal layer after the metal layer is disposed on the frying layer is 4B or more by the cross-cut evaluation method.

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