Conductive laminate, and touch panel comprising same

Abstract

The present invention is relates to conductive laminate. The conductive laminate is applied to a touch panel or touch screen, thereby exhibiting excellent durability, and a pressure-sensitive adhesive layer included in the conductive laminate may prevent a change in resistance of a conductive layer, and effectively inhibit lift-off or peeling, or generation of bubbles at a pressure-sensitive adhesive interface. As a result, performances of the touch panel or touch screen including the conductive laminate may be stably maintained for a long time.

Claims

1. A conductive laminate, comprising: a substrate layer; a pressure-sensitive adhesive layer formed on one or both surfaces of the substrate layer; and a conductive layer present between the substrate layer and the pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition comprising 100 parts by weight of a pressure-sensitive adhesive polymer, and 0.1 to 35 parts by weight of a polymerized product of a monomer mixture comprising a thiol compound, wherein the thiol compound and the monomer mixture constitute the polymerized product, wherein the polymerized product has a weight average molecular weight of 1,000 to 200,000, wherein the conductive layer has a resistance change rate of 10% or less, and wherein the thiol compound is a compound of Formula 1:
HSR[Formula 1] where R is an unsubstituted alkyl group or an alkyl group substituted with at least one substituent selected from the group consisting of a thiol group, a hydroxyl group and an oxyranyl group, or a substituent of Formula 2, ##STR00002## where A is an alkylene group, R.sub.a is hydrogen, an alkyl group, or -L.sub.1-C(-L.sub.2-OC(O)-L.sub.3-SH).sub.nR.sub.(3-n), in which L.sub.1 to L.sub.3 are each independently an alkylene group, R is hydrogen or an alkyl group, and n is a number from 1 to 3.

2. The conductive laminate of claim 1, further comprising a metal mesh layer present between the substrate layer and the pressure-sensitive adhesive layer.

3. The conductive laminate of claim 2, wherein the metal mesh layer comprises silver, copper or an alloy thereof.

4. The conductive laminate of claim 1, further comprising a transparent substrate attached to the pressure-sensitive adhesive layer.

5. The conductive laminate of claim 1, wherein the pressure-sensitive adhesive layer has a peeling strength of 1,900 gf/25 mm or more at a room temperature, relative to a polycarbonate film when the pressure-sensitive adhesive layer is formed on the polycarbonate film.

6. The conductive laminate of claim 1, wherein the pressure-sensitive adhesive polymer comprises 80 to 99.99 parts by weight of a (meth)acrylic acid ester monomer and 0.01 to 20 parts by weight of a copolymerizable monomer having a crosslinkable functional group.

7. The conductive laminate of claim 6, wherein the crosslinkable functional group is a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group or a derivative thereof.

8. The conductive laminate of claim 1, wherein the pressure-sensitive adhesive polymer has a weight average molecular weight of 300,000 to 2,000,000.

9. The conductive laminate of claim 1, wherein the thiol compound is a compound in which R of Formula 1 is an unsubstituted alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted with a hydroxyl group, or an alkyl group having 1 to 20 carbon atoms substituted with an oxyranyl group.

10. The conductive laminate of claim 1, wherein the monomer mixture comprises 0.01 to 10 parts by weight of a thiol compound, relative to 100 parts by weight of the monomer.

11. The conductive laminate of claim 1, wherein the monomer mixture comprises a (meth)acrylic acid ester monomer.

12. The conductive laminate of claim 1, wherein the monomer mixture comprises a copolymerizable monomer having a crosslinkable functional group.

13. The conductive laminate of claim 1, wherein the pressure sensitive adhesive composition further comprises a multifunctional crosslinking agent at 0.01 to 10 parts by weight, relative to 100 parts by weight of the pressure-sensitive adhesive polymer.

14. A touch panel, comprising the conductive laminate of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 to 3 are diagrams of exemplary conductive laminates.

(2) FIG. 4 is a diagram showing a method of measuring a resistance change rate.

MODES OF INVENTION

(3) Hereinafter, exemplary embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms. The following embodiments are described in order to enable those of ordinary skill in the related art to embody and practice the present invention.

(4) Hereinafter, each physical properties shown in Examples and Comparative Examples were evaluated by the following methods.

(5) 1. Durability Test

(6) A sample was prepared by laminating a hard coating layer of a poly(ethylene terephthalate)(PET) film (thickness: 100 m) and a polycarbonate(PC) film (thickness: 1 mm) by means of a pressure-sensitive adhesive layer of Example or Comparative Example, cutting the resulting product to a size of 50 mm (width)100 mm (length), and putting the cut product in an autoclave at 60 C. under 5 atm for 30 minutes. Afterward, the sample was left at 80 C. for about 240 hours, and then durability was evaluated.

(7) The durability was evaluated by examining whether or not generation of bubbles and occurrence of lift-off/peeling according to the following criteria:

(8) <Criteria for Evaluating Bubble Generation>

(9) O: When bubbles were not observed or a small amount of bubbles having a diameter of 100 m or less were observed at a pressure-sensitive adhesive interface using an optical microscope

(10) X: When bubbles having a diameter of 100 m or more, or groups of bubbles having a diameter of 100 m or less were observed at a pressure-sensitive adhesive interface using an optical microscope

(11) <Criteria for Evaluating Lift-off/Peeling>

(12) O: When there was no lift-off and peeling at a pressure-sensitive adhesive interface

(13) X: When lift-off and/or peeling occurred at a pressure-sensitive adhesive interface

(14) 2. Resistance Change Rate Test

(15) A resistance change rate was measured by the method shown in FIG. 5. As a commercially available conductive film, a PET film (201) (hereinafter, referred to as a conductive PET) having an ITO conductive layer (202) formed on one surface thereof was cut into a size of 30 mm50 mm (widthlength). Subsequently, as shown in FIG. 5, a silver paste (502) was applied to both ends of the film to have a width of 10 mm, and plasticized at 150 C. for 30 minutes. A double-sided pressure-sensitive adhesive tape having releasing films (102) attached to both surfaces thereof, which was manufactured in Example or Comparative Example, was cut into a size of 30 mm40 mm (widthlength), and the releasing film was removed from one surface of the pressure-sensitive adhesive tape, and then a pressure-sensitive adhesive layer (101) was attached to the conductive layer (202) by matching a center of the pressure-sensitive adhesive layer (101) with a center of the PET film (201). Then, an initial resistance R.sub.i of the conductive layer (202) was measured using a resistance measurer (501). After measuring the initial resistance, the sample having the structure shown in FIG. 5 was maintained at 60 C. and a relative humidity of 90% for 240 hours, and a resistance R.sub.a of the conductive layer (202) was measured using the same measurer (501) used above. The measured value was put into Equation 1 to measure a resistance change rate R.
R=[(R.sub.aR.sub.i)/R.sub.i]100[Equation 1]

(16) 3. Evaluation of Peeling Strength

(17) A double-sided pressure-sensitive adhesive tape of Example or Comparative Example was cut to have a width of 1 inch, and attached to a PC film by pressing the tape twice with a 2 kg roller. After about 30 minutes of the attachment, a peeling strength was measured while the pressure-sensitive adhesive tape was peeled in a width direction at a peeling angle of 180 and a peeling rate of 300 mm/min. A peeling strength of each pressure-sensitive adhesive tape was measured three times by the same method, and an average of the measured peeling strengths was used as a representative value.

(18) 4. Measurement of Molecular Weight (Mw)

(19) A molecular weight was measured using a GPC apparatus under the following conditions. To prepare a calibration curve, measurement results were converted using standard polystyrene produced by Agilent System.

(20) <Conditions for Measuring Molecular Weight (Mw)>

(21) Measurer: Agilent GPC (Agilent 1200 series, USA)

(22) Column: Two PL Mixed Bs connected

(23) Column Temperature: 40 C.

(24) Eluent: Tetrahydrofuran (THF)

(25) Flow Rate: 1.0 mL/min

(26) Concentration: Up to 2 mg/mL (100 l injection)

Preparation Example 1: Preparation of Acrylic Polymer Solution (A)

(27) 58 parts by weight of n-butyl acrylate, 40 parts by weight of methyl acrylate, and 2 parts by weight of 2-hydroxyethyl acrylate were put into a reaction vessel in which a nitrogen gas was refluxed and a cooling apparatus was equipped to facilitate temperature control. Subsequently, 200 parts by weight of ethyl acetate was added as a solvent with respect to 100 parts by weight of a monomer. The reaction vessel was purged with a nitrogen gas for about 60 minutes, a temperature was maintained at about 60 C., and 0.04 parts by weight of azobisisobutyronitrile(AIBN) was input as a reaction initiator to initiate a reaction. After about 8 hours of the reaction, a reaction product was diluted with ethyl acetate to have a solid content of about 30 wt %, thereby obtaining an acrylic polymer solution (A) having a weight average molecular weight (Mw) of about 800,000 and a polydispersity index (M.sub.w/M.sub.n) of about 5.2.

Preparation Example 2: Preparation of Acrylic Low Molecular Weight Polymer Solution (B)

(28) 58 parts by weight of n-butyl acrylate, 40 parts by weight of methyl acrylate, and 2 parts by weight of 2-hydroxyethyl acrylate were put into the reaction vessel as used in Preparation Example 1, and 100 parts by weight of ethyl acetate was put thereinto as a solvent with respect to 100 parts by weight of the monomer. The reaction vessel was purged with a nitrogen gas for about 60 minutes, a temperature was maintained at about 60 C., and 5 parts by weight of N-dodecane thiol was put with respect to 100 parts by weight of the monomer. In addition, 0.04 parts by weight of azobisisobutyronitrile(AIBN) was input as a reaction initiator with respect to 100 parts by weight of the monomer to initiate a reaction. After about 8 hours of the reaction, a reaction product was diluted with ethyl acetate to have a solid content of about 30 wt %, thereby obtaining a low molecular weight polymer solution (B) having a weight average molecular weight (Mw) of about 6,000 and a polydispersity index (M.sub.w/M.sub.n) of about 1.8.

Preparation Example 3: Preparation of Acrylic Polymer Solution (C)

(29) 58 parts by weight of n-butyl acrylate, 40 parts by weight of methyl acrylate, and 2 parts by weight of 2-hydroxyethyl acrylate were put into the reaction vessel as used in Preparation Example 1, and 150 parts by weight of ethyl acetate was put thereinto as a solvent with respect to 100 parts by weight of the monomer. The reaction vessel was purged with a nitrogen gas for about 60 minutes, a temperature was maintained at about 60 C., and 0.03 parts by weight of N-dodecane thiol was put with respect to 100 parts by weight of the monomer. In addition, 0.04 parts by weight of azobisisobutyronitrile(AIBN) was put as a reaction initiator with respect to 100 parts by weight of the monomer to initiate a reaction. After about 8 hours of the reaction, a reaction product was diluted with ethyl acetate to have a solid content of about 30 wt %, thereby obtaining a polymer solution (C) having a weight average molecular weight (Mw) of about 780,000 and a polydispersity index (M.sub.w/M.sub.n) of about 2.8.

Example 1

(30) The acrylic polymer solution (A) of Preparation Example 1, the acrylic low molecular weight polymer solution (B) of Preparation Example 2, and an isocyanate crosslinking agent (toluene diisocyanate (TDI)) were blended, thereby obtaining a pressure-sensitive adhesive composition. The polymer solution(B) was blended to have solid content in the solution(B) of 0.5 parts by weight, relative to 100 parts by weight of the solid content in the solution (A), and the crosslinking agent was blended at 0.3 parts by weight, relative to 100 parts by weight of the solid content in the solution(A). The pressure-sensitive adhesive composition was coated on a releasing-treated surface of a releasing-treated PET film (thickness: about 50 m), and the coated product was left at about 120 C. for about 3 minutes, thereby forming a transparent pressure-sensitive adhesive layer having a thickness of about 50 m. Subsequently, a releasing-treated surface of another releasing-treated PET Film (thickness: about 50 m) was laminated on the pressure-sensitive adhesive layer, thereby manufacturing a pressure-sensitive adhesive tape having the structure of FIG. 1.

Examples 2 and 3 and Comparative Examples 1 to 3

(31) Pressure-sensitive adhesive tapes were manufactured by the same method as described in Example 1, except components blended in the preparation of the pressure-sensitive adhesive composition and ratios thereof were controlled as shown in Table 1.

(32) TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 1 2 3 Blending ratio (A) 100 100 100 100 100 of polymer (B) 0.5 5 30 40 solution (C) 100 Blending ratio of 0.3 0.3 0.3 0.3 0.3 0.3 crosslinking agent Unit of blending ratio: weight ratio (in case of polymer solution, based on solid content) Crosslinking agent: isocyanate-based crosslinking agent (TDI)

(33) Physical properties measured with respect to the pressure-sensitive adhesive tape of Example or Comparative Example were summarized in Table 2.

(34) TABLE-US-00002 TABLE 2 Example Comparative Example 1 2 3 1 2 3 Generation of bubbles X Lift-off/peeling X Peeling strength 2390 2440 2310 2430 2150 1820 (gf/25 mm) Resistance change rate 7 4 2 14 2 5 (%)