CN111356252A - Electrothermal film, conductive silver paste and preparation method of electrothermal film - Google Patents

Abstract

The application discloses an electrothermal film, conductive silver paste and a preparation method of the electrothermal film. The conductive film includes: a film which is a mixture containing a carbon material and polyethylene; and the printed electrode is arranged on the surface of the film and is a mixture containing a silver material and polyamide resin. The heat-generating film using a polyethylene substrate has good adhesion to the printed electrode based on a polyamide resin, and the printed electrode has good resistance to bending.

Description

Electrothermal film, conductive silver paste and preparation method of electrothermal film

Technical Field

The application belongs to the field of heating films and relates to an electrothermal film, conductive silver paste and a preparation method of the electrothermal film.

Background

The electric heating technology has the obvious advantages of clean energy, high heat conversion efficiency, convenient pavement design and the like, and is widely applied to the fields of modern buildings, heating engineering, decoration and fitment and the like. Among various electric heating technologies, the heat-generating film has many advantages that the conventional electric heating element does not have, and is widely applied, such as planar heat generation, hard damage, strong shape variability, and the like.

Among various electrothermal films, an electrothermal film based on a carbon material such as graphene, conductive carbon black, etc. has advantages of low resistance, high thermal conductivity, high heat-resistant stability, etc. A common electrothermal film structure using carbon material includes: the heating film comprises a heating film and electrodes arranged on the heating film, wherein the polymer matrix material in the heating film can be polyethylene, polypropylene, polyethylene terephthalate and the like. The development of the electrode with strong adhesive force and bending resistance on the heating film made of the polyvinyl material has important significance.

Disclosure of Invention

The application aims to provide an electrothermal film, conductive silver paste and a preparation method of the electrothermal film, so that an electrode which has strong adhesive force and is resistant to bending is prepared on a heating film made of a polyvinyl material.

According to an aspect of the present application, there is provided an electrothermal film comprising:

a film which is a mixture containing a carbon material and polyethylene;

and the printed electrode is arranged on the surface of the film and is a mixture containing a silver material and polyamide resin.

Preferably, the carbon material comprises graphene, carbon fibers, carbon nanotubes, conductive graphite or conductive carbon black.

Preferably, the silver material includes a plate-like silver powder, silver nanoparticles, or silver nanowires.

Preferably, the printed electrode further comprises a thickening agent.

According to an aspect of the present application, there is provided a conductive silver paste, comprising: a silver material, a polyamide resin, and an organic solvent.

Preferably, the organic solvent comprises N, N-dimethylacetamide, N-dimethylformamide, monohydric alcohols of C3-C10, dicarboxylic acid esters, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate or ethylene glycol butyl ether.

Preferably, the conductive silver paste further comprises a thickener, and the thickener is polyamide wax powder, polyethylene wax powder or fumed silica.

According to one aspect of the present application, there is provided a method of manufacturing an electrothermal film, comprising the steps of:

providing a film, wherein the film is polyethylene dispersed with carbon materials;

the conductive silver paste as described above was printed on the surface of the film.

Has the advantages that:

(1) in the electrothermal film provided by the application, the adhesion between the heating film adopting the polyethylene matrix and the printing electrode based on the polyamide resin is good, and the bending resistance of the printing electrode is good;

(2) the conductive silver paste provided in the application is very suitable for preparing electrodes on the heating film of the polyethylene substrate doped with the carbon material, the preparation process is simple, and the requirement on the surface adhesiveness of the heating film is low.

Drawings

Fig. 1 is a schematic structural view of an electrothermal film according to an embodiment of the present application.

Detailed Description

The technical solutions in the examples of the present application will be described in detail below with reference to the embodiments of the present application. It should be noted that the described embodiments are only some embodiments of the present application, and not all embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Unless otherwise defined, all terms (including technical and scientific terms) in the specification may be defined as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and may not be interpreted in an idealized or overly formal sense unless expressly so defined. Furthermore, unless expressly stated to the contrary, the terms "comprises" and "comprising," when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. Thus, the above wording will be understood to mean that the stated elements are included, but not to exclude any other elements.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present embodiments.

The following definitions apply to aspects described in relation to some embodiments of the invention, and these definitions may be extended herein as well.

As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Unless the context clearly dictates otherwise, reference to an object may include multiple objects.

As used herein, the term "adjacent" refers to being proximate or contiguous. The adjacent objects may be spaced apart from each other, or may be in actual or direct contact with each other. In some cases, adjacent objects may be connected to each other, or may be integrally formed with each other.

As used herein, the term "connected" refers to an operative coupling or link. The linked objects may be directly coupled to each other or may be indirectly coupled to each other via another set of objects.

As used herein, relative terms, such as "inside," "interior," "exterior," "top," "bottom," "front," "back," "upper," "lower," "vertical," "lateral," "above … …," and "below … …," refer to the orientation of a group of objects relative to one another as a matter of manufacture or use, for example, according to the drawings, but do not require the particular orientation of the objects during manufacture or use.

According to some exemplary embodiments of the present application, as shown in fig. 1, there is provided an electric heating film including: a film 11, the composition of which is a mixture containing a carbon material and polyethylene; and a printed electrode 13 disposed on the surface of the film 11, wherein the printed electrode 13 is a mixture of a silver-containing material and a polyamide resin.

When the printed electrode 13 is connected to an external power source, when a current passes through the thin film 11, the carbon material has a certain conductivity, so that the entire surface of the thin film 11 generates heat, thereby forming a planar heat source.

In the embodiment of the present application, the polymer matrix in the film 11 is a common polyethylene material, and the polyethylene material-based heating film has many advantages, such as good chemical stability, resistance to most of acid and alkali erosion, and the like. However, the heat-generating film based on the polyethylene substrate also has major disadvantages such as very poor surface adhesion, resulting in difficulty in obtaining good wet spreading thereon with conventional conductive silver paste, and difficulty in forming weak bonding effects such as van der waals force and dispersion force; and the compactness of the structure prevents the swelling and penetration of the conductive silver paste, and an effective mechanical anchoring effect and an interpenetrating network structure cannot be formed. This makes it very difficult to produce silver printed electrodes on heat-generating films.

In order to solve the problem of poor surface adhesion of the polyethylene matrix-based heating film, the film may be subjected to corona treatment or other treatment to increase the surface adhesion, but this will undoubtedly result in more complicated preparation process of the electrothermal film.

In the embodiments of the present application, by selecting a polyamide resin as a polymer matrix of a printed electrode, the related experimental results show that the adhesion of a silver printed electrode based on a polyamide resin on a heat-generating film of a polyethylene matrix is very good, which may be due to a large amount of polar groups such as amino groups, carbonyl groups, amide groups, etc. contained in the polyamide resin; meanwhile, the prepared printed electrode is not broken after being folded in half. Therefore, the step of additionally processing the heating film to increase the surface adhesiveness of the heating film can be avoided, and the preparation process of the electrothermal film is simplified.

In one embodiment, the carbon material content of the film 11 is preferably in the range of 10 wt% to 90 wt%, and the polyethylene content is preferably in the range of 10 wt% to 90 wt%. When the content of the carbon material is too low, the heat generating performance of the film 11 is too poor; when the content of the carbon material is too high and the content of the polyethylene is too low, the bending resistance and the surface adhesion of the film 11 are not good.

In the present application, the carbon material includes, but is not limited to, graphene, carbon fiber, carbon nanotube, conductive graphite, or conductive carbon black. The carbon materials have good conductivity, and when the carbon materials are dispersed in polyethylene to form a film, the film also has certain conductivity.

In one embodiment, the silver material includes, but is not limited to, a plate-like silver powder, silver nanoparticles, or silver nanowires. The content of the silver material in the printed electrode 13 is preferably 50 wt% to 90 wt%. The particle diameter (length and width directions) of the plate-like silver powder may be 1 to 20 μm; the silver nanoparticles may have a particle size of 50 to 500 nanometers; the silver nanowires may have a diameter of 10 to 100 nanometers and a length of 1 to 20 micrometers.

The printed electrode 13 may be a mixture containing a silver material, a polyamide resin, and a thickener. The thickener includes, but is not limited to, polyamide wax powder, polyethylene wax powder, or fumed silica, etc. These thickeners are introduced during the preparation of the conductive silver paste to optimize the performance of the conductive silver paste and ultimately remain in the silver print electrode.

According to an aspect of the present application, there is provided a conductive silver paste, including: a silver material, a polyamide resin, and an organic solvent. Preferably, the conductive silver paste further comprises a thickener, wherein the silver material is 35 wt% to 65 wt%, the polyamide resin is 5 wt% to 20 wt%, the organic solvent is 25 wt% to 50 wt%, and the thickener is 0.5 wt% to 5 wt%, according to the content. The conductive silver paste is very suitable for preparing the silver printing electrode on the heating film with the polyethylene substrate, the adhesive force of the obtained silver printing electrode on the heating film with the polyethylene substrate can reach 5B level (ASTM level), and the silver printing electrode is not cracked after being folded.

In the conductive silver paste, the organic solvent includes, but is not limited to, N-dimethylacetamide, N-dimethylformamide, C3-C10 monohydric alcohol, dicarboxylic acid ester, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, or ethylene glycol butyl ether. The thickener includes, but is not limited to, polyamide wax powder, polyethylene wax powder, or fumed silica, etc.

In one embodiment, the conductive silver paste can be prepared as follows:

preparation of the polyamide resin System: mixing polyamide resin and an organic solvent, heating to 70 ℃, stirring for dissolving, and cooling to room temperature;

preparation of the thickener system: mixing the thickening agent and the organic solvent, heating to 80 ℃, stirring, and cooling to room temperature;

and sequentially adding the polyamide resin system, the thickening agent system and the silver material into a double-planet stirrer, stirring for 1 hour, uniformly mixing, adding the uniformly mixed material into a three-roller machine, grinding and dispersing, and storing for later use after the grinding fineness is below 15 micrometers.

In one embodiment of the present application, there is provided a method for preparing an electrothermal film, including the steps of: providing a film, wherein the film is polyethylene dispersed with carbon materials; the conductive silver paste as described above was printed on the surface of the film.

In one embodiment, the film is prepared by mixing a carbon material with polyethylene and casting the mixture into a film.

Methods of printing conductive silver paste on the surface of the film include, but are not limited to, inkjet printing, spray coating, screen printing, and the like.

In one embodiment, the printed electrode is prepared on the surface of the thin film in the following manner: and (3) carrying out screen printing on the surface of the film to obtain an electrode pattern, and then drying the printed pattern at the temperature of 60-80 ℃ for 1-10 minutes.

Example 1

Provided is a conductive silver paste, including: 50 wt% of a plate-like silver powder, 37 wt% of isopropyl alcohol, 10 wt% of a polyamide resin, and 3 wt% of a polyamide wax powder.

Example 2

Provided is a conductive silver paste, including: 50 wt% of a plate-like silver powder, 37 wt% of N, N-dimethylacetamide, 5 wt% of a polyamide resin, 5 wt% of a terpene resin, and 3 wt% of a polyamide wax powder.

Comparative example 1

Provided is a conductive silver paste, including: 50 wt% of flake silver powder, 37 wt% of isophorone, 10 wt% of polyurethane and 3 wt% of polyamide wax powder.

Comparative example 2

Provided is a conductive silver paste, including: 50 wt% of a plate-like silver powder, 37 wt% of N, N-dimethylacetamide, 10 wt% of a terpene resin, and 3 wt% of a polyamide wax powder.

The conductive silver pastes of example 1, example 2, comparative example 1 and comparative example 2 were screen printed on untreated films of polyethylene substrate containing conductive carbon black, respectively, to prepare electrode patterns, and the electrode patterns were dried at 80 ℃.

Adhesion on films of polyethylene substrates was tested using a hundred grid and 3M600 tape and the test results were classified as 5B, 4B, 3B, 2B, 1B grades (ASTM grades), with 5B being the best adhesion. And the sheet resistance of the electrode is tested by a four-probe tester. And testing whether the electrode is broken after 180-degree folding. The relevant test results are as follows:

	adhesion force	Sheet resistance/m omega/□/1mil	Whether it is broken after being folded in half
				Example 1	5B	140	Does not break
Example 2	5B	150	Does not break
				Comparative example 1	2B	130	Does not break
Comparative example 2	5B	200	Fracture of

From the above experimental results, it was found that the adhesion of the polyamide resin-based printed electrode (example 1) to the polyethylene base film reached a level of 5B, the adhesion performance was very good, and the printed electrode was not broken after being folded in half; and the terpene resin (example 2) containing a part in the material of the printed electrode based on polyamide resin also had very good adhesion and did not break after being folded in half. In contrast, in comparative example 2, when the printed electrode based on the terpene resin was used, the printed electrode was broken after being folded in half, although the adhesion of the printed electrode was excellent. In contrast, in comparative example 1, when the printed electrode based on polyurethane was used, the printed electrode had poor adhesion and was broken after being folded in half.

Although the present disclosure has been described and illustrated in greater detail by the inventors, it should be understood that modifications and/or alterations to the above-described embodiments, or equivalent substitutions, will be apparent to those skilled in the art without departing from the spirit of the disclosure, and that no limitations to the present disclosure are intended or should be inferred therefrom.

Claims (8)

1. An electrothermal film, comprising:

a film which is a mixture containing a carbon material and polyethylene;

and the printed electrode is arranged on the surface of the film and is a mixture containing a silver material and polyamide resin.

2. The electrothermal film of claim 1, wherein the carbon material comprises graphene, carbon fibers, carbon nanotubes, conductive graphite, or conductive carbon black.

3. The electrothermal film of claim 1, wherein the printed electrode further comprises a thickener.

4. The electrothermal film of claim 1, wherein the silver material comprises flake silver powder, silver nanoparticles or silver nanowires.

5. The conductive silver paste is characterized by comprising: silver material, polyamide resin and organic solvent.

6. The conductive silver paste of claim 5, wherein the organic solvent comprises N, N-dimethylacetamide, N-dimethylformamide, C3-C10 monohydric alcohol, dicarboxylic acid ester, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, or ethylene glycol butyl ether.

7. The conductive silver paste of claim 5, wherein the conductive silver paste further comprises a thickener comprising polyamide wax powder, polyethylene wax powder or fumed silica.

8. A preparation method of an electrothermal film is characterized by comprising the following steps:

providing a film, wherein the film is polyethylene dispersed with carbon materials;

printing the conductive silver paste of any one of claims 5 to 7 on the surface of the film.

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