Graphene heat dissipation baking varnish

Abstract

A highly porous heat dissipation coating by graphene-rich baking varnish consists of: graphene nanoflakes, at least one dispersants, binders, and carriers. The amount of graphene-rich nanoflakes accounts for 10 to 70 wt % of solid composition of a graphene baking varnish. The at least one dispersant is non-ionic or ionic dispersant. The binder is made of thermoplastic polymers. The carrier is selected from aqueous liquids, organic solvents, or a combination thereof. A post-baking treatment at relative high temperature (100 to 400° C.) is applied for enhancing the adhesion of heat dissipation coating on metal surface. Accordingly, the graphene-rich baking varnish enhances adhesion and improves heat dissipation rate by convection and radiation.

Claims

1. A graphene-rich baking varnish consists of: graphene nanoflakes, at least one dispersants, binders, and carriers; wherein the solid content of graphene-rich baking varnish is 10 to 70 wt %; wherein the amount of graphene nanoflakes accounts for 10 to70 wt % of solid composition of a graphene-rich baking varnish; wherein the at least one dispersant is non-ionic or ionic dispersant; wherein the binder is made of thermoplastic polymers; and wherein the carrier is selected from aqueous liquids, organic solvents, or a combination thereof;

2. The graphene-rich baking varnish as claimed in claim 1, wherein the at least one dispersant is added at 1 to 10 wt % of the solid composition of the graphene-rich baking varnish.

3. The graphene-rich baking varnish as claimed in claim 1, wherein the binder is accounted for 10 to 85 wt % of the solid composition of the graphene-rich baking varnish.

4. The graphene-rich baking varnish as claimed in claim 1, wherein the carrier accounts for 30 to 90 wt % of the total composition of a graphene-rich baking varnish.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a schematic view illustrating graphene flake was used as auxiliary filler for paint.

[0036] FIG. 2 is an amplified schematic view of a portion A of FIG. 1 illustrating large amount of heat insulator plastic binders and color fillers in paint results in a poor heat conduction of coating.

[0037] FIG. 3 is a schematic view illustrating graphene flake was used as primary filler for paint according to a preferred embodiment of the present invention.

[0038] FIG. 4 is an amplified schematic view of a portion B of FIG. 3 illustrating large amount of heat conductive graphene nanoflakes in paint results in a high heat dissipation performance coating on metal surface according to the preferred embodiment of the present invention.

[0039] FIG. 5 is a SEM image of binder-rich graphene baking varnish coated on metal surface.

[0040] FIG. 6 is a SEM image of graphene-rich graphene baking varnish coated on metal surface.

[0041] FIG. 7 is a SEM image of commercial black paint coated on metal surface.

[0042] FIG. 8 shows Table 1, in which the heat dissipation test of Cu metal with various coating according to the preferred embodiment of the present invention.

[0043] FIG. 9 shows Table 2, in which the solid composition of various graphene-based polymer composition painting.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] As illustration in FIGS. 3 and 4, numerical reference 10 denotes a metal surface, numerical reference 12 designates plastic binders and color fillers, numerical reference 13 indicates graphene flake, and numerical reference 14 represents paint with high content of graphene flakes, wherein an amount of graphene flakes 13 is raised and content of plastic binders and color fillers 12 is reduced in paint so as to form a porous graphene flake coating layer, thus overcoming the above issue in heat dissipation paint.

[0045] In such architecture of graphene-rich baking varnish, porous graphene flake layer can play as a role of micro fin to enlarge the contact area to surroundings and improve the heat dissipation rate by convection and radiation. So compared to binder-rich and color filler-rich paint, graphene-rich paint exhibits high heat conductivity and supplies a more smooth heat conduction pathway.

[0046] However, the adhesion of graphene-rich coating layer will become terrible when we reduce the content of plastic binders. For example, some graphene-rich baking varnish coating will be peeled off by tape before baking treatment.

[0047] In order to enhance the adhesion of the graphene flakes 13, we need to use thermoplastic polymers as binders. And a baking treatment at relatively high temperature (100 to 400° C.) is requested after coating.

[0048] At relatively high baking temperature, the well-mixed thermoplastic binders in coating layer of graphene mixture will soften and flow down along the graphene flakes 13 to the metal surface 10, which not only can enhance the adhesion of the graphene paint 14 in relatively low binder content but also form a protection film on the metal surface 10.

[0049] Therefore, a method of enhancing adhesion of the graphene-rich paint 14 contains steps of:

[0050] 1). coating graphene-rich baking varnish on a surface of the metal 10;

[0051] 2). drying and baking graphene-rich paint at relatively high temperature (100 to 400° C.); and

[0052] 3). cooling to a room temperature to form an uniform graphene-rich baking varnish.

[0053] Thereby, the graphene-rich baking varnish after baking at relatively high temperature don't be peeled off by the tape.

[0054] In this invention, using thermoplastic polymers as binder of the graphene-rich baking varnish and post-baking treatment at relative high temperature (100 to 400° C.) are disclosed for enhancing the adhesion of heat dissipation coating on metal surface.

[0055] The graphene-rich baking varnish consists of graphene nanoflakes, at least one dispersants, binders, and carriers.

[0056] The solid content of graphene-rich baking varnish is 10 to 70 wt %.

[0057] The primary material for thermal dissipation and radiation is the graphene nanoflakes, wherein a thickness of the graphene nanoflakes ranges from 1 to 100 nm, and a size of the graphene nanoflakes is from 0.1 to 100 μm, wherein the amount of graphene nanoflakes accounts for 10 to 70 wt % of solid composition of the graphene-rich baking varnish.

[0058] The at least one dispersant is non-ionic or ionic dispersant and is added at 1 to 10 wt % of the solid composition of the graphene-rich baking varnish.

[0059] The binder is made of thermoplastic polymers and is accounted for 10 to 85 wt % of the solid composition of the graphene-rich baking varnish.

[0060] The carrier is selected from aqueous liquids, organic solvents, or a combination thereof, which depends on what thermoplastic binders were used.

[0061] The carrier accounts for 30 to 90 wt % of total composition of the graphene-rich baking varnish.

[0062] Preferably, the graphene-rich baking varnish is coated on metal surface in any one of screen printing, spraying, dipping, and pasting manners.

[0063] Preferably, a post-baking treatment at relative high temperature (100 to 400° C.) is applied for enhancing the adhesion of heat dissipation coating on metal surface.

EXAMPLE 1

Binder-Rich Graphene Baking Varnish

[0064] A binder-rich graphene baking varnish was used as a example for heat dissipation coating of metal surface. This binder-rich graphene baking varnish consists of 90 g water, 1.5 g BYK disperbyk-191 dispersant, 15 g graphene flake, 75 g polyvinyl acetate binder. So there is 82.0 wt % binder resin, 16.4 wt % graphene flake, 1.6 wt % dispersant in the solid composition. The binder-rich graphene baking varnish was sprayed on the Cu foil surface and dried at 100° C. to form a uniform coating. After drying, the sample was baked at 200° C. for 30 min to enhance the adhesion of baking varnish on metal surface.

EXAMPLE 2

Graphene-Rich Baking Varnish

[0065] A graphene-rich graphene baking varnish was used to enhance the heat dissipation ability for metal surface coating. This graphene-rich graphene baking varnish consists of 60 g water, 1.2 g BYK disperbyk-191 dispersant, 12 g graphene flake, 5 g polyvinyl acetate binder. So there is 27.5 wt % binder resin, 65.9 wt % graphene flake, 6.6 wt % dispersant in the solid composition. The graphene-rich graphene baking varnish was sprayed on the Cu foil surface and dried at 100° C. to form a uniform coating. After drying, the sample was baked at 200° C. for 30 min to enhance the adhesion of baking varnish on metal surface.

COMPARATIVE EXAMPLE 1

Commercial Black Painting

[0066] The commercial Telox 109 black paint was used as a comparative example to show the advantages of graphene baking varnish. This commercial black paint consists of carbon black filler, acrylic resin, dimethyl ether solvent, and other additives. Due to the commercial black paint already exhibited a very good adhesion on the surface Cu metal, no any further baking treatment was applied for this sample.

COMPARATIVE EXAMPLE 2

White Ceramic Painting

[0067] A white ceramic baking varnish was used as a comparative example to show the advantages of graphene baking varnish. This white ceramic baking varnish consists of 60 g water, 1.2 g BYK disperbyk-191 dispersant, 12 g boron nitride (BN) flake, 5 g polyvinyl acetate binder. So there is 27.5 wt % binder resin, 65.9 wt % BN flake, 6.6 wt % dispersant in the solid composition. The white ceramic baking varnish was sprayed on the Cu foil surface and dried at 100° C. to form a uniform coating. After drying, the sample was baked at 200° C. for 30 min to enhance the adhesion of baking varnish on metal surface.

[0068] SEM surface morphologies of example 1, 2, and comparative example 1 were observed. From the comparison between FIG. 5, FIG. 6 and FIG. 7, the metal surface coated by graphene-rich baking varnish exhibits a highly porous morphology (example 2, FIG. 6); however, a smooth and dense surface was observed for binder-rich graphene baking varnish (example 1, FIG. 5) and commercial black paint (comparative example 1, FIG. 7).

[0069] From the heat dissipation ability of all sample in FIG. 8, graphene-rich baking varnish shows the highest temperature cooling of Cu metal. In addition, coating graphene baking varnish on the surface of ceramic varnish can further enhance its heat dissipation rate. The high heat dissipation performance of graphene-rich baking varnish is attributable to that the porous architecture can raise the heat dissipation rate by both thermal convection and radiation, which is totally different to prior arts.

[0070] While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.