Capacitive touch panel
Provided is a capacitive touch panel which has enhanced sensitivity and is usable in an image display panel, etc. in this capacitive touch panel, a window, a first transparent film having a first transparent conductive electrode pattern formed on one surface thereof, and a second transparent film having a second transparent conductive electrode pattern which is formed on one surface thereof and disposed with respect to the first transparent film in such a manner as to allow a capacitance to be formed therebetween, are stacked in turn. The capacitive touch panel comprises a first transparent inter-layer resin provided between the window and the first transparent film, and a second transparent inter-layer resin provided between the first transparent film and the second transparent film, wherein the first transparent inter-layer resin has a dielectric constant greater than that of the second transparent inter-layer resin.
1. A capacitive touch panel comprising:
a window;
a first transparent film having a first transparent conductive electrode pattern formed on one surface thereof;
a second transparent film having a second transparent conductive electrode pattern formed on one surface thereof and disposed with respect to the first transparent film in such a manner as to allow a capacitance to be formed therebetween, are stacked in turn;
a first transparent inter-layer resin provided between the window and the first transparent film, the first transparent inter-layer resin is in direct contact with the first transparent film, and a surface of the first transparent conductive electrode pattern farthest from the window is coplanar with a surface of the first transparent inter-layer resin farthest from the window; and
a second transparent inter-layer resin provided between the first transparent film and the second transparent film, wherein
the first transparent inter-layer resin has a dielectric constant greater than that of the second transparent inter-layer resin.
2. The capacitive touch panel as defined in claim 1 , wherein each of the dielectric constant of the first transparent inter-layer resin and the dielectric constant of the second transparent inter-layer resin is in the range of 2 to 8.
3. The capacitive touch panel as defined in claim 1 , wherein the dielectric constant of the first transparent inter-layer resin is greater than the dielectric constant of the second transparent inter-layer resin by at least 30% thereof.
4. The capacitive touch panel as defined in claim 1 , wherein each of the first transparent inter-layer resin and the second transparent inter-layer resin has a thickness of 25 μm or more.
5. The capacitive touch panel as defined in claim 1 , wherein the first transparent conductive electrode pattern is formed on a surface of the first transparent film between the first transparent film and the window, and the second transparent conductive electrode pattern is formed on a surface of the second transparent film between the second transparent film and the window.
6. The capacitive touch panel as defined in claim 1 , wherein the first transparent conductive electrode pattern is formed on a surface of the first transparent film between the first transparent film and the window, and the second transparent conductive electrode pattern is formed on a surface of the second transparent film on a side opposite to the window.
7. The capacitive touch panel as defined in claim 1 , wherein at least one of the first transparent inter-layer resin and the second transparent inter-layer resin is a cured body of an ultraviolet-curable liquid resin.
8. The capacitive touch panel as defined in claim 7 , wherein the ultraviolet-curable liquid resin has a viscosity of 100,000 mPa·s to 500 mPa·s.
9. The capacitive touch panel as defined in claim 7 , wherein the ultraviolet-curable liquid resin is comprised of an ultraviolet-curable optical resin adhesive composition comprising: a urethane acrylate-based polymer containing a (meth)acryloyl group and a hydroxyl group on side chains thereof; and a photopolymerization initiator.
10. The capacitive touch panel as defined in claim 9 , wherein the urethane acrylate-based polymer has a weight-average molecular weight of 5,000 to 500,000.
11. The capacitive touch panel as defined in claim 9 , wherein the ultraviolet-curable optical resin adhesive composition further comprises a monofunctional (meth)acrylate compound as a reactive diluent.
12. The capacitive touch panel as defined in claim 9 , wherein a mixing amount of the photopolymerization initiator is in the range of 0.1 to 30 weight % with respect to an entirety of the ultraviolet-curable optical resin adhesive composition.
13. The capacitive touch panel as defined in claim 1 , wherein, at least one of the first transparent inter-layer resin and the second transparent inter-layer resin is composed of a pressure-sensitive adhesive.
14. The capacitive touch panel as defined in claim 13 , wherein the pressure-sensitive adhesive is selected from the group consisting of an acryl-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a fluorine-based pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, a polyether-based pressure-sensitive adhesive, and mixtures thereof.
15. The capacitive touch panel as defined in claim 13 , wherein the first transparent inter-layer resin is composed of a pressure-sensitive adhesive, and wherein the pressure-sensitive adhesive of the first transparent inter-layer resin comprises a polymer formed from a monomer component selected from the group consisting of (meth)acrylate, methyl acrylate, ethyl acrylate and butyl acrylate each containing an alkoxyl group and/or a hydroxyl group.
16. The capacitive touch panel as defined in claim 13 , wherein the second transparent inter-layer resin is composed of a pressure-sensitive adhesive, and wherein the pressure-sensitive adhesive of the second transparent inter-layer resin comprises a polymer formed from a monomer component which is one or more selected from the group consisting of: an alkyl acrylate ester containing a straight- or branched-chain alkyl group of 6 to 10 carbon atoms; an alkyl methacrylate ester containing a straight- or branched-chain alkyl group of 1 to 10 carbon atoms; a (meth)acrylate ester containing an aromatic or alicyclic hydrocarbon group; a nitrogen-containing monomer; and a fluorine-containing monomer.
17. The capacitive touch panel as defined in claim 13 wherein each of the first transparent inter-layer resin and the second transparent inter-layer resin has a total light transmittance of 90% or more in a visible light wavelength region.
18. The capacitive touch panel as defined in claim 13 , wherein each of the first transparent inter-layer resin and the second transparent inter-layer resin has a haze of 3% or less.
19. An image display panel comprising the capacitive touch panel as defined in claim 1 , and a liquid crystal panel laminated to the capacitive touch panel.
20. An image display panel comprising the capacitive touch panel as defined in claim 1 , and an organic EL panel laminated to the capacitive touch panel.