Pressure-sensitive adhesive sheet for touch panel, laminate for touch panel, and capacitance-type touch panel

Patent metadata

Field	Value
Publication number	US-10464290-B2
Application number	US-201715665509-A
Country	US
Kind code	B2
Filing date	Aug 1, 2017
Priority date	Mar 4, 2015
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive sheet for a touch panel which is excellent for the operability of a capacitance-type touch panel, which is able to suppress the occurrence of malfunctions in a capacitance-type touch panel in a wide range of temperature environments from low temperatures to high temperatures, and which is also excellent in pressure-sensitive adhesion. In addition, another object of the present invention is to provide a laminate for a touch panel and a capacitance-type touch panel which include a pressure-sensitive adhesive sheet for a touch panel. In the pressure-sensitive adhesive sheet for a touch panel of the present invention, a relative dielectric constant obtained by impedance measurement at 1 MHz at 20° C. is 4.0 or more, a temperature dependency obtained from a temperature dependency evaluation test is 25% or less, and a 180 degree peel strength with respect to glass is 0.2 to 1.2 N/mm.

First claim

What is claimed is:

1. A pressure-sensitive adhesive sheet for a touch panel,
wherein a relative dielectric constant obtained by impedance measurement at 1 MHz at 20° C. is 4.0 or more,
a temperature dependency obtained from a temperature dependency evaluation test is 25% or less, and
a 180 degree peel strength with respect to glass is 0.2 to 1.2 N/mm, wherein the temperature dependency evaluation test comprises interposing a pressure-sensitive adhesive sheet for a touch panel between aluminum electrodes while a temperature is raised from −10° C. to 40° C. at intervals of 10° C., the relative dielectric constant of the pressure-sensitive adhesive sheet is calculated using impedance measurement at 1 MHz at each temperature at intervals, and the minimum value and the maximum value are selected from the relative dielectric constant calculated at each temperature at intervals, and a value obtained from the expression [{(maximum value−minimum value)/minimum value}×100] (%) is taken as the temperature dependency,
wherein the pressure-sensitive adhesive sheet comprising:
a first layer having a relative dielectric constant determined by impedance measurement at 1 MHz at 20° C. of 4.0 or more and a temperature dependency A of 25% or less; and
a second layer having a relative dielectric constant determined by impedance measurement at 1 MHz at 20° C. of 4.0 or less and a temperature dependency B of 20% or less,
wherein the second layer is provided on both surfaces of the first layer, and
the relative dielectric constant of the first layer at 20° C. is higher than the relative dielectric constant of the second layer at 20° C.

2. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein the temperature dependency is 20% or less.

3. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein a ratio of a thickness of the second layer with respect to a thickness of the first layer is 0.05 to 0.5.

4. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein a glass transition temperature of the first layer is 0° C. or less.

5. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein, in the temperature dependency evaluation test, in a case where the first layer is used instead of the pressure-sensitive adhesive sheet for a touch panel, a maximum value of the relative dielectric constant of the first layer is in a range of −10° C. to 40° C.

6. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein the first layer includes a (meth)acrylic resin and the (meth)acrylic resin has a repeating unit derived from a monomer having at least one group selected from a group consisting of a hydroxyl group, a nitrogen-containing functional group, and a carboxyl group, and
the monomer is used in an amount of 10% by mass or more with respect to 100% by mass of the monomer total mass used for polymerization of the (meth)acrylic resin.

7. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 ,
wherein the second layer includes a (meth)acrylic resin and a hydrophobic compound.

8. The pressure-sensitive adhesive sheet for a touch panel according to claim 7 ,
wherein the hydrophobic compound included in the second layer includes at least one resin selected from a group consisting of a terpene-based resin, a rosin-based resin, a coumarone indene-based resin, a rubber-based resin, and a styrene-based resin.

9. The pressure-sensitive adhesive sheet for a touch panel according to claim 7 ,
wherein a content of the hydrophobic compound is 20% to 80% by mass with respect to the second layer total mass, and is 1% to 30% by mass with respect to the pressure-sensitive adhesive sheet for a touch panel total mass.

10. A laminate for a touch panel comprising:
the pressure-sensitive adhesive sheet for a touch panel according to claim 1 ; and
a capacitance-type touch panel sensor.

11. The laminate for a touch panel according to claim 10 , further comprising:
a protective substrate,
wherein the capacitance-type touch panel sensor, the pressure-sensitive adhesive sheet for a touch panel, and the protective substrate are in this order.

12. A capacitance-type touch panel comprising at least:
a display device;
the pressure-sensitive adhesive sheet for a touch panel according to claim 1 ; and
a capacitance-type touch panel sensor, in this order.

13. The pressure-sensitive adhesive sheet for a touch panel according to claim 2 ,
wherein a ratio of a thickness of the second layer with respect to a thickness of the first layer is 0.05 to 0.5.

14. The pressure-sensitive adhesive sheet for a touch panel according to claim 2 ,
wherein a glass transition temperature of the first layer is 0° C. or less.

15. The pressure-sensitive adhesive sheet for a touch panel according to claim 3 ,
wherein a glass transition temperature of the first layer is 0° C. or less.

16. The pressure-sensitive adhesive sheet for a touch panel according to claim 2 ,
wherein, in the temperature dependency evaluation test, in a case where the first layer is used instead of the pressure-sensitive adhesive sheet for a touch panel, a maximum value of the relative dielectric constant of the first layer is in a range of −10° C. to 40° C.

17. The pressure-sensitive adhesive sheet for a touch panel according to claim 3 ,
wherein, in the temperature dependency evaluation test, in a case where the first layer is used instead of the pressure-sensitive adhesive sheet for a touch panel, a maximum value of the relative dielectric constant of the first layer is in a range of −10° C. to 40° C.

18. The pressure-sensitive adhesive sheet for a touch panel according to claim 4 ,
wherein, in the temperature dependency evaluation test, in a case where the first layer is used instead of the pressure-sensitive adhesive sheet for a touch panel, a maximum value of the relative dielectric constant of the first layer is in a range of 10° C.to 40° C.

Assignees

• Fujifilm Corp

Inventors

• Tanaka Satoshi
• Naoi Kenji

Classifications

• C09J145/02

  Coumarone-indene polymers · CPC title

• C09J145/00

  Adhesives based on homopolymers or copolymers of compounds having no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic or in a heterocyclic system; Adhesives based on derivatives of such polymers (based on polymers of cyclic esters of polyfunctional acids C09J131/00; based on polymers of cyclic anhydrides or imides C09J135/00) · CPC title

• C09J193/04

  Rosin · CPC title

• C09J133/04

  Homopolymers or copolymers of esters {(C09J143/04 takes precedence)} · CPC title

• B32B9/045

  of synthetic resin · CPC title