FLEXIBLE CONDUCTIVE FILM AND ITS PREPARATION METHOD

Abstract

A flexible conductive film is comprised of a flexible base and a conductive layer coated on it. The flexible base uses Surlyn resin as the matrix. It uses silver nanowire as the conductive layer.

Claims

1. A flexible conductive film, wherein the flexible conductive film comprising: a flexible base film and a conductive layer coated on a surface of the flexible base film, and the flexible base film includes the following parts by weight: 70-90 parts of aqueous medium; 5-20 parts of Surlyn resin; 1-5 parts of antioxidants; Leveling agent 0.5-2 parts; Functional particles 0.1-0.5 parts; 1-2 parts of antifoaming agent.

2. The flexible conductive film according to claim 1, wherein the flexible base film has a thickness of 20 to 50 μm.

3. The flexible conductive film according to claim 1, wherein said functional particles are nano TiO.sub.2, nano ZnO, nano SiO.sub.2, any one of nano-CeO.sub.2 inorganic nano-filled particles.

4. The flexible conductive film according to claim 1, wherein the aqueous medium is water with a resistivity of 18 MΩ*cm at 25° C.; and the antioxidant is an compound of phosphite and phenolic antioxidants; the leveling agent is an aqueous leveling agent; the antifoaming agent is a silicone antifoaming agent.

5. The flexible conductive film according to claim 1, wherein the conductive layer is a conductive paste coated and cured on a surface of the flexible base film, and the conductive paste is made by mixing any one or more of silver nanowires, gold nanowires, copper nanowires, nickel nanowires, silver nanoparticles, gold nanoparticles, copper nanoparticles, and nickel nanoparticles.

6. The flexible conductive film according to claim 5, wherein the conductive layer is a silver nanowire conductive paste coated and cured on a surface of the flexible base film.

7. The flexible conductive film according to claim 6, wherein the silver nanowire conductive paste contains 0.1-0.5% of silver nanowires, and the silver nanowires have a diameter of 10-100 nm, The aspect ratio is ≥1000.

8. A method of preparing a flexible conductive film according to claim 1, comprising the steps of: (1) weigh the flexible base film raw material according to the parts by weight of each component, add the aqueous medium to the three-necked flask, heat to a slightly boiling state, add Surlyn resin while stirring, and stir at a speed of 100-200 rpm, After the Surlyn resin is dissolved, an antioxidant, a leveling agent, a functional particle, an antifoaming agent are sequentially added, and the mixture is continuously stirred for 2 to 2.5 hours to obtain a flexible base film coating liquid, which is ready for use; (2) the flexible base film coating liquid prepared in the step (1) is coated on the carrier film by slit coating at a coating speed of 10-20 m/min, and cured to obtain a flexible base film; (3) uniformly coating the conductive paste on the surface of the flexible base film by slit coating, the coating speed is 10-20 m/min, and the curing temperature is 70-130° C. to obtain a conductive layer; (4) the flexible base film and the conductive layer after curing are removed from the carrier film by laser mode to obtain a flexible conductive film.

9. The method for preparing a flexible conductive film according to claim 8, wherein the curing method of the flexible base film in the step (2) is performed by hot air curing or far infrared heating curing or electric heating curing.

10. The method of preparing a flexible conductive film according to claim 9, wherein the hot air curing temperature is 50 to 100° C., and the electric heating curing temperature is 80 to 130° C.

11. The method for preparing a flexible conductive film according to claim 8, wherein the viscosity of the flexible base film coating liquid in the step (1) is 5-30 mpa.s, and the surface tension is 20-40 mN/m.

12. The method for preparing a flexible conductive film according to claim 8, wherein the carrier film is any one of PET, PMMA, COP, which play a bearing role in the preparation process of the conductive film.

13. The method for preparing a flexible conductive film according to claim 12, wherein the thickness of the carrier film is 100-188 μm.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Please find below a clear and comprehensive description of the technical scheme of this invention with an embodiment. Apparently, the embodiment described represents only some, not all embodiments. Based on embodiments in this invention, all other embodiments obtained by those skilled in this art not through creative work fall into the scope of protection of this invention.

[0034] Embodiment 1

[0035] A type of flexible conductive film, which consist of a flexible base and a conductive layer coated on it. The flexible base is comprised of below components with below parts by weight: [0036] Ultra-pure water, 70; [0037] Surlyn resin, 5; [0038] Antioxidant, 1; [0039] Leveling agent, 0.5; [0040] Functional particle, 0.1; [0041] Defoamer, 1.

[0042] The flexible conductive film preparation method in this embodiment includes the following steps: [0043] (1) Weigh and take raw materials of the flexible base as per parts by weight, add ultra-pure water into a 3-neck flask, heat to slightly boil, and add Surlyn resin while stirring at 100 rpm. After Surlyn resin dissolves, add antioxidants, leveling agents, functional particles, and defoamers in turn, continue to stir for 2 h until well mixed, to make flexible base coating liquid for usage in the following steps; [0044] (2) Unreel 188 μm thick PET (polyethylene terephthalate) at 100 m/min and conduct corona treatment on PET (polyethylene terephthalate) base film with 1.0 kw power; apply the flexible base coating liquid prepared in Step (1) on one side of the corona treated PET (polyethylene terephthalate) in the die coating way, at the flow of 50 ml/min and speed of 10 m/min; cure with hot wind at 50° C., or electrical heating at 130° C. , for 2 min, to make flexible bases 20 μm thick; [0045] (3) Apply silver nanowire conductive pulps evenly on the surface of flexible bases in the die coating way, with pump speed 30 ml/min, wet film thickness 30 μm, application speed 10 m/min, curing temperature gradually increasing from 70° C. to 130° C. for 2 min, to form an even conductive layer; [0046] (4) Remove the cured flexible base and conductive layer from the carrier film using laser, to obtain a flexible conductive film.

[0047] Conduct a weathering test on the flexible conductive film made in this embodiment under the following test conditions: [0048] UV (Ultraviolet rays) resistance test: irradiation intensity 0.35 W/M.sup.2, temperature 60° C., duration 240 h; [0049] Xenon weathering test: irradiation intensity 0.8 W/M.sup.2, temperature 40° C., humidity 55%, duration 240 h; [0050] High temperature and humidity test: temperature 85° C., humidity 85%, duration 240 h; [0051] Thermal shock test: low temperature −30° C., high temperature 90° C., duration 240 h. The weathering test results are shown in Table 1.

TABLE-US-00001 TABLE 1 Flexible conductive film weathering test results Xenon High UV weathering temperature Thermal Weathering test resistance test and humidity shock Resistance R (%) 0.5-1.0 0.5-1.0 0.5-1.0 0.5-1.0 Transmittance (%) 0.2-0.8 0.2-0.8 0.2-0.8 0.2-0.8 Haze (%) 0.1-0.3 0.1-0.3 0.1-0.3 0.1-0.3 Aberration b (%) 0.1-0.4 0.1-0.4 0.1-0.4 0.1-0.4 Adhesion 100/100 100/100 100/100 100/100 Resistance to <8 <10 <10 <10 chemicals (ΔR/R, %)

[0052] Embodiment 2

[0053] One type of flexible conductive film, which consists of a flexible base and a conductive layer applied on it. The flexible base is comprised of below components with below parts by weight: [0054] Ultra-pure water, 80; [0055] Surlyn resin, 15; [0056] Antioxidant, 3; [0057] Leveling agent, 1.5; [0058] Functional particle, 0.3; [0059] Defoamer, 1.5.

[0060] The flexible conductive film preparation method in this embodiment includes the following steps: [0061] (1) Weigh and take raw materials of the flexible base as per parts by weight, add ultra-pure water into a 3-neck flask, heat to slightly boil, and add Surlyn resin while stirring at 150 rpm. After Surlyn resin dissolves, add antioxidants, leveling agents, functional particles, and defoamers in turn, continue to stir for 2.5 h until well mixed, to make flexible base coating liquid; [0062] (2) Unreel 188 μm thick PET (polyethylene terephthalate) at 100 m/min and conduct corona treatment on PET (polyethylene terephthalate) base film with 1.0 kw power; apply the flexible base coating liquid prepared in Step (1) on one side of the corona treated PET (polyethylene terephthalate) in the die coating way, at the flow of 30 ml/min and speed of 15 m/min; cure with hot wind at 80° C., or electrical heating at 100° C., for 1.5 min, to make flexible bases 30 μm thick; [0063] (3) Apply silver nanowire conductive pulps evenly on the surface of flexible bases in the die coating way, with pumping speed 30 ml/min, wet film thickness 30 μm, application speed 10 m/min, curing temperature gradually increasing from 70° C. to 130° C. for 2 min, to form an even conductive layer; [0064] (4) Remove the cured flexible base and conductive layer from the carrier film using laser, to obtain a flexible conductive film.

[0065] Conduct a weathering test on the flexible conductive film made in this embodiment under the same test conditions as embodiment 1.

[0066] The test results are shown in Table 2.

TABLE-US-00002 TABLE 2 Flexible conductive film weathering test results Xenon High UV weathering temperature Thermal Weathering test resistance test and humidity shock Resistance R (%) 0.5-1.0 0.5-1.0 0.5-1.0 0.5-1.0 Transmittance (%) 0.2-0.8 0.2-0.8 0.2-0.8 0.2-0.8 Haze (%) 0.1-0.3 0.1-0.3 0.1-0.3 0.1-0.3 Aberration b* (%) 0.1-0.4 0.1-0.4 0.1-0.4 0.1-0.4 Adhesion 100/100 100/100 100/100 100/100 Resistance to <8 <10 <10 <10 chemicals (ΔR/R, %)

[0067] Embodiment 3

[0068] A type of flexible conductive film, which consists of a flexible base and a conductive layer coated on it. The flexible base is comprised of below components with below parts by weight: [0069] Ultra-pure water, 90; [0070] Surlyn resin, 20; [0071] Antioxidant, 5; [0072] Leveling agent, 2; [0073] Functional particle, 0.5; [0074] Defoamer, 2.

[0075] The flexible conductive film preparation method in this embodiment includes the following steps: [0076] (1) Weigh and take raw materials of the flexible base as per parts by weight, add ultra-pure water into a 3-neck flask, heat to slightly boil, and add Surlyn resin while stirring at 200 rpm. After Surlyn resin dissolves, add antioxidants, leveling agents, functional particles, and defoamers in turn, continue to stir for 2 h until well mixed, to make flexible base coating liquid; [0077] (2) Unreel 188 μm thick PET (polyethylene terephthalate) at 100 m/min and conduct corona treatment on PET (polyethylene terephthalate) base films with 1.0 kw power; apply the flexible base coating liquid prepared in Step (1) on one side of the corona treated PET (polyethylene terephthalate) in the die coating way, at the flow of 50 ml/min and speed of 20 m/min; cure with hot wind at 100° C., or electrical heating at 80° C., for 1 min, to make flexible bases 50 μm thick; [0078] (3) Apply silver nanowire conductive pulp evenly on the surface of flexible base in the die coating way, with pump speed 30 ml/min, wet film thickness 30 μm, application speed 10 m/min, curing temperature gradually increasing from 70° C. to 130° C. for 2 min, to form an even conductive layer; [0079] (4) Remove the cured flexible base and conductive layer from the carrier film using laser, to obtain a flexible conductive film.

[0080] Conduct a weathering test on the flexible conductive film made in this embodiment under the same test conditions as embodiment 1. The test results are shown in Table 3.

TABLE-US-00003 TABLE 3 Flexible conductive film weathering test results Xenon High UV weathering temperature Thermal Weathering test resistance test and humidity shock Resistance R (%) 0.5-1.0 0.5-1.0 0.5-1.0 0.5-1.0 Transmittance (%) 0.2-0.8 0.2-0.8 0.2-0.8 0.2-0.8 Haze (%) 0.1-0.3 0.1-0.3 0.1-0.3 0.1-0.3 Aberration b* (%) 0.1-0.4 0.1-0.4 0.1-0.4 0.1-0.4 Adhesion 100/100 100/100 100/100 100/100 Resistance to <8 <10 <10 <10 chemicals (ΔR/R, %)

[0081] Comparative Embodiment 1

[0082] In this comparative embodiment, the conductive film uses 50 μm thick PET as base, on which silver nanowire conductive pulps are applied evenly in the die coating way, with pumping speed 30 ml/min, wet film thickness 30 μm, application speed 10 m/min, curing temperature gradually increasing from 70° C. to 130° C. for 2 min, to form an even conductive layer. In this way, a transparent conductive film is made.

[0083] Conduct an optical performance test on flexible conductive films made in embodiments 1-3 and come up with results shown in Table 4.

TABLE-US-00004 TABLE 4 Flexible conductive film optical performance test result Optical property Embodiment 1 Embodiment 2 Embodiment 3 Transmittance (%) 93.1 91.5 90.0 Haze (%) 0.12 0.35 0.5 Aberration b* (%) 0.5 0.8 1.2 Refractive index 1.71 (@550 nm) Double refraction (Δn) 0.03

[0084] Conduct a bending performance test on conductive films made in embodiments 1-3 and comparative embodiment 1, with R=2 mm, for 100,000 times, 200,000 times, 300,000 times, and 500,000 times respectively, and the resistance change and film surface status for each is shown in Table 5.

TABLE-US-00005 TABLE 5 Conductive film bending performance test 100,000 200,000 300,000 500,000 Bending performance test times times times times Resistance R Embodiment 1 0.2 0.3 0.35 0.5 (%) Embodiment 2 0.2 0.3 0.35 0.5 Embodiment 3 0.25 0.35 0.45 0.55 Comparative 0.5 5 20 — example 1 Film surface Embodiment 1 No crack No crack No crack No crack status Embodiment 2 No crack No crack No crack No crack Embodiment 3 No crack No crack No crack No crack Comparative Slight Crack Crack Crack and no example 1 blushing resistance

[0085] From Table 1-5, it can be seen that conductive films made in each embodiment of this invention, with a flexible base with Surlyn resin as matrix and highly conductive and flexible silver nanowire as a conductive layer, features great optical properties such as high transmittance, 0 haze, and low b*, able to meet demands for transparent conductive films. Besides, it features great flexibility and conductivity. After being bent for 200,000 to 500,000 times, the conductive to layer shows no crack or fracture, with resistance change rate below 5%, which makes it meet demands of flexible optoelectronics on conductive films, and thus widely used in flexible electronic components. It can be also seen from the weathering test that conductive films made in the embodiment of this invention features great weather resistance, which makes it suitable for various environment and widens its scope of application.

[0086] Above are further descriptions of this invention using embodiments, but it shall be understood that such detailed descriptions shall not be considered as restrictive of nature and scope of this invention. All kinds of modifications made by those skilled in this art to the above embodiments after reading this specification fall into the scope of protection of this invention.