阅读说明：本技术 一种多孔弹性导电复合薄膜及其制备方法 (Porous elastic conductive composite film and preparation method thereof ) 是由 王华涛 于阳韬 崔洪鑫 张涛 钟博 于 2021-08-09 设计创作，主要内容包括：本发明提供了一种多孔弹性导电复合薄膜及其制备方法,所述复合薄膜是以导电纳米材料为填料,水性高分子为基体,通过机械发泡、涂膜、干燥等工艺形成多孔弹性导电复合薄膜。使用机械发泡代替有机分相法发泡,可有效的避免使用有机溶剂,减少污染。本发明提供的方法具有方法简单、可靠、操作性强的特点,有效的避免使用有机溶剂,减少污染。本发明提供的方法可应用于众多功能纳米材料与水性高分子多孔复合材料的制备。本发明提供的方法所制备的薄膜具有多孔、导电好、能压缩回弹、压缩率大、厚度可控的特点。本发明提供的方法所制备的多孔弹性导电复合薄膜可广泛应用于电磁屏蔽、柔性传感和柔性发热等领域。(The invention provides a porous elastic conductive composite film and a preparation method thereof. Mechanical foaming is used for replacing organic phase separation foaming, so that organic solvents can be effectively avoided, and pollution is reduced. The method provided by the invention has the characteristics of simplicity, reliability and strong operability, effectively avoids using organic solvents and reduces pollution. The method provided by the invention can be applied to the preparation of various functional nano materials and aqueous polymer porous composite materials. The film prepared by the method provided by the invention has the characteristics of being porous, good in electric conduction, capable of compressing and rebounding, large in compression ratio and controllable in thickness. The porous elastic conductive composite film prepared by the method can be widely applied to the fields of electromagnetic shielding, flexible sensing, flexible heating and the like.)

1. A preparation method of a porous elastic conductive composite film comprises the following steps:

s01, preparing conductive filler slurry: adding a conductive nano material serving as a filler into water, adding a surface modifier, and stirring and dispersing to obtain conductive filler slurry;

s02, foaming: adding a foaming agent and a foam stabilizer into a polymer matrix, and stirring to form foamed polymer slurry;

s03, mixing: adding the conductive filler slurry into the foamed polymer slurry, and stirring and mixing to obtain mixed slurry;

s04, coating: coating the mixed slurry on a substrate by a coating process;

s05, drying: and drying the coated material, and stripping the coated material from the substrate to obtain the porous elastic conductive composite film.

2. The method of claim 1,

the conductive nano material used in the step S01 is at least one of graphene, graphite nanosheet, carbon nanotube, carbon black, silver nano material, gold nano material, copper nano material, nickel nano material, aluminum nano material, nano indium tin oxide material and nano silicon material, and the conductive nano material used accounts for 2.0-23.0% of the conductive filler slurry by mass; the surface modifier is at least one of carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxypropyl cellulose and polyvinylpyrrolidone, and accounts for 0.1-1.0% of the conductive filler slurry by mass; the stirring time is 0.5-3.0 h.

3. The method of claim 1,

the polymer matrix used in the step S02 is one or more selected from polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polyethylene glycol, waterborne epoxy resin, waterborne phenolic resin and waterborne polyurethane; the solid content is 20-45%.

4. The method of claim 1,

the foaming agent used in the step S02 is at least one of disodium lauryl sulfosuccinate, sodium lauryl sulfate, magnesium lauryl sulfate and magnesium nitrate hexahydrate; the foam stabilizer is at least one of polydimethylsiloxane and hydrated silicic acid; the foaming agent accounts for 0.5 to 5.0 percent of the mass of the foaming polymer slurry; the foam stabilizer accounts for 0.5-5.0% of the foamed polymer slurry by mass; the stirring time is 0.5-3.0 h.

5. The method of claim 1,

in the mixed slurry obtained in the step S03, the foamed polymer slurry accounts for 50-80% of the mass of the mixed slurry, the conductive filler slurry accounts for 20-50% of the total mass of the mixed slurry, and the stirring time is 0.5-3.0 h.

6. The method of claim 1,

the stirring head of the stirrer used for stirring in the steps S01, S02 and S03 is one of a flat blade stirring head, a high-speed hinge stirring head, a spiral blade stirring head, a turbine type stirring head, a screw type stirring head and a commercial milk frother rotary head.

7. The method of claim 1,

the coating process adopted in the step S04 is one of a scraper coating and a slit coating; the thickness of the coating film is 120-15000 microns; the substrate is a polyethylene terephthalate release film.

8. The method of claim 1, wherein:

and the drying in the step S05 is at least one of drying of a bottom plate and drying of hot air, the drying temperature is 40-180 ℃, and the drying time is 0.5-2.0 h.

9. A porous elastic conductive composite film is characterized in that,

the porous elastic conductive composite film is prepared by the method of any one of claims 1 to 8, has a thickness of 0.04 to 10.00mm, a resistivity of 1 to 42000 Ω -cm, a porosity of 16 to 78%, and a compression rebound of 12 to 70%.

Technical Field

The invention relates to a porous elastic conductive composite film and a preparation method thereof, belonging to the field of composite materials.

Background

Along with the development of the society, a porous elastic conductive composite film is needed, has the characteristics of good conductivity, compression resilience and high compression rate, and is applied to the fields of electromagnetic shielding, flexible sensing, flexible heating and the like. However, it is difficult for the conventional metal material to satisfy both the compression spring back and the film-like technical requirements. The conductive compressible resilient film can be prepared by a method of compounding conductive nano-filler and high polymer. For example, carbon black is compounded with a silica gel polymer matrix to prepare a conductive composite. The characteristics of compressibility of the polymer matrix are utilized, so that the composite material can be endowed with compression rebound and a certain compression rate. However, the material prepared by the method has the characteristics of high conductivity and large compressibility.

The porous structure may impart greater compressibility to the composite. There are several methods for preparing porous conductive films. For example, a three-dimensional porous graphene/polyurethane flexible stress-strain sensor and a preparation method thereof (application No. 202011196286.7) report that a porous film is prepared by a template method, a polyurethane porous template is used firstly, and then a conductive layer is grown on the side wall of the porous template. For another example, in a method for preparing an electromagnetic shielding polyurethane lightweight material (application No. 201910218320.7), pores are generated by using a method of mixing an a/B material, but in the foaming method, the expansion rate is large, the thickness is not easy to control, and a film material is not suitable to be prepared.

There is also a method of forming a porous structure by solvent dissolution (also called phase separation, or coagulation bath). For example: and (2) forming the polyurethane composite solution containing the conductive nano filler and the organic solvent, immersing the formed polyurethane composite solution into a coagulating bath, and dissolving the formed polyurethane composite solution into the coagulating bath through the organic solvent to form a porous structure. The existence of pores and conductive filler endows the composite material with the characteristics of conductivity, compression rebound and large compressibility. The process relates to the problems of use, recovery and discharge of organic solvents, and brings about great hidden danger of environmental pollution. For example: compounding graphene with N, N-dimethylformamide and polyurethane, soaking the graphene in water, quickly dissolving the N, N-dimethylformamide in the water, and drying the material to obtain the graphene/polyurethane material. The material has the characteristics of porosity, electric conductivity, compression resilience and larger compression ratio. In a graphene-containing polyurethane porous film, a method for producing the same, and use thereof (application No. 201710830503.5), one of N, N-dimethylformamide, dioxane, and tetrahydrofuran is used as a solvent.

The method for preparing the porous material by phase separation needs to use organic solvents such as N, N-dimethylformamide and the like, and the N, N-dimethylformamide and water are infinitely mutually soluble, so that the wastewater treatment is difficult, and the potential hazard of great environmental pollution exists. If the wastewater containing N, N-dimethylformamide flows out of the nature, the N, N-dimethylformamide enters the aquatic organisms and then indirectly enters the human body through the biological chain, so that the human health is greatly harmed. Therefore, an environment-friendly technology for preparing the porous elastic conductive film is urgently needed.

The porous elastic conductive film is prepared by adopting a method of replacing organic solvent phase separation with mechanical foaming, and has the advantages that air holes are introduced through mechanical stirring and foaming agent reaction, organic solvents are not used, the environment is protected, and the prepared composite film has the advantages of being porous, good in conductivity, capable of compressing and rebounding, large in compression ratio and controllable in thickness.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a porous elastic conductive composite film and a preparation method thereof so as to achieve better comprehensive performances of conductivity, resilience, compressibility and the like.

In order to achieve the purpose, the invention is realized by the following technical scheme:

s01, preparing conductive filler slurry: adding the conductive nano material serving as a filler into water, adding a surface modifier, and stirring and dispersing to obtain the conductive filler slurry.

S02, foaming: adding a foaming agent and a foam stabilizer into a polymer matrix, and stirring to form foamed polymer slurry;

s03, mixing: adding the conductive filler slurry into the foamed polymer slurry, and stirring and mixing to obtain mixed slurry;

s04, coating: coating the mixed slurry on a substrate by a coating process;

s05, drying: and drying the coated material, and stripping the coated material from the substrate to obtain the porous elastic conductive composite film.

Further, in the porous elastic conductive composite film and the preparation method thereof, the conductive filler used in the step S01 is at least one of graphene, graphite nanosheet, carbon nanotube, carbon black, silver nanomaterial, gold nanomaterial, copper nanomaterial, nickel nanomaterial, aluminum nanomaterial, nano indium tin oxide material, and nano silicon material, and the used conductive nanomaterial accounts for 2.0-23.0% of the conductive filler slurry by mass;

further, in the porous elastic conductive composite film and the preparation method thereof, the polymer matrix used in the step S01 is one or more selected from polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polyethylene glycol, aqueous epoxy resin, aqueous phenolic resin and aqueous polyurethane, and the solid content is 20-45%.

Further, in the porous elastic conductive composite film and the preparation method thereof, the surfactant used in the step S01 is at least one of carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxypropyl cellulose, and polyvinylpyrrolidone, the used surface modifier accounts for 0.1-1.0% by mass of the conductive filler slurry, and the stirring time is 0.5-3.0 hours.

Further, in the porous elastic conductive composite film and the preparation method thereof, the foaming agent used in the step S02 is at least one of disodium lauryl sulfosuccinate, sodium dodecyl sulfate, magnesium dodecyl sulfate and magnesium nitrate hexahydrate; the main component of the foam stabilizer is at least one of polydimethylsiloxane and hydrated silicic acid; the foaming agent accounts for 0.5-5% of the foamed polymer slurry by mass; the foam stabilizer accounts for 0.5-5.0% of the foamed polymer slurry by mass; the stirring time is 0.5-3.0 h.

Further, in the porous elastic conductive composite film and the preparation method thereof, in the mixed slurry obtained in the step S03, the foamed polymer slurry accounts for 50-80% of the mass of the mixed slurry, the conductive filler slurry accounts for 20-50% of the total mass of the mixed slurry, and the stirring time is 0.5-3.0 hours.

Further, in the porous elastic conductive composite film and the preparation method thereof, the stirring head of the stirrer used for stirring in the steps of S01, S02 and S03 is one of a flat blade stirring head, a high-speed folding blade stirring head, a spiral blade stirring head, a turbine type stirring head, a screw type stirring head and a rotating head of a commercial milk foaming machine.

Further, in the porous elastic conductive composite film and the preparation method thereof, the coating process adopted in the step S04 is one of a doctor blade coating and a slit coating; the thickness of the coating film is 120-15000 microns; the substrate is a polyethylene terephthalate release film.

Further, in the above porous elastic conductive composite film and the preparation method thereof, the drying in the step S05 is at least one of soleplate drying and hot air drying; the drying temperature is 40-180 ℃, and the drying time is 0.5-2.0 h.

The porous elastic conductive composite film is prepared by the method, has the thickness of 0.04-10.00mm, the resistivity of 1-42000 omega cm, the porosity of 16-78%, and can rebound under compression, and the compression ratio of 12-70%.

The porous elastic conductive composite film prepared by adopting the processes of mechanical foaming, film coating, drying and the like overcomes the defects of the traditional porous conductive polymer composite material, and has the main advantages that:

1) the method provided by the invention has the characteristics of simplicity, reliability and strong operability, effectively avoids using organic solvents and reduces pollution;

2) the method provided by the invention can be applied to the preparation of various functional nano materials and aqueous polymer porous composite materials;

3) the film prepared by the method provided by the invention has the characteristics of being porous, good in conductivity, large in compression ratio and controllable in thickness, and can be compressed and rebounded;

4) the porous elastic conductive composite film prepared by the method can be widely applied to the fields of electromagnetic shielding, flexible sensing, flexible heating and the like.

Drawings

FIG. 1 is a process flow diagram of the present invention for preparing a porous elastic conductive composite film. Fig. 2 is a surface SEM photograph of the porous elastic conductive composite film prepared in example 2. Fig. 3 is a sectional SEM photograph of the porous elastic conductive composite film prepared in example 2.

Detailed Description

Specific embodiments of the present invention will be described in detail below, and it should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that these specific details need not be employed to practice the present invention. In other instances, well-known structures, materials, or methods have not been described in detail in order to avoid obscuring the present invention.

Reference throughout this specification to "one embodiment," "an embodiment," "one example" or "an example" means that a particular feature, structure or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples.

Example 1

S01, preparing conductive filler slurry: weighing a certain mass of conductive nano material (graphite nanosheet) as a filler, adding the conductive nano material into deionized water, adding a surface modifier (carboxymethyl cellulose), and stirring and dispersing to obtain conductive filler slurry; the conductive nano material accounts for 23% of the mass of the conductive filler slurry, the added carboxymethyl cellulose accounts for 1.0% of the mass of the conductive filler slurry, a stirring head of a stirrer used for stirring and dispersing is a flat-blade stirring head, and the stirring time is 3.0 hours.

S02, foaming: adding a foaming agent and a foam stabilizer into a polymer matrix, and stirring to form foamed polymer slurry; wherein the foaming agent is disodium lauryl sulfosuccinate, and the mass of the foaming agent accounts for 0.5 percent of that of the foaming polymer slurry; the foam stabilizer is polydimethylsiloxane, and the mass of the foam stabilizer accounts for 0.5 percent of that of the foamed polymer slurry; the polymer matrix is aqueous polyurethane emulsion with solid content of 45%; the stirring head of the stirrer used for stirring is a flat blade stirring head, and the stirring time is 0.5 h.

3, S03, mixing: adding the conductive filler slurry obtained in the step S01 into the foamed polymer slurry obtained in the step S02, stirring and mixing, and carrying out secondary foaming to obtain mixed slurry; wherein the foamed polymer slurry accounts for 50% of the mass of the mixed slurry, the conductive filler slurry accounts for 50% of the total mass of the mixed slurry, the stirring time is 3.0h, and the stirring head of the stirrer used for stirring is a flat blade stirring head.

S04, coating the mixed slurry on a substrate through a coating process; wherein, the film coating process is a slit film coating process, the film coating thickness is 120 microns, and the substrate is a polyethylene terephthalate release film.

5, S05, drying: drying the coated material, and stripping the coated material from the substrate to obtain a porous elastic conductive composite film; wherein the drying mode is hot air drying, the drying temperature is 120 ℃, and the drying time is 0.5 h.

6. The porous elastic conductive composite film obtained through the steps S01-S05 has the thickness of 0.04mm, the resistivity of 1 omega cm, the porosity of 16 percent and the compression rebound, and the compression ratio of 12 percent.

Example 2

S01, preparing conductive filler slurry: weighing a certain mass of conductive nano material (carbon nano tube) as a filler, adding the conductive nano material into deionized water, adding a surface modifier (hydroxypropyl cellulose), and stirring and dispersing to obtain conductive filler slurry; the mass percentage of the used conductive nano material in the conductive filler slurry is 2.0%, the mass of the added hydroxypropyl cellulose in the conductive filler slurry is 0.1%, and the stirring head of a stirrer for stirring and dispersing is a spiral-surface blade stirring head, and the stirring time is 0.5 h.

S02, foaming: adding a foaming agent and a foam stabilizer into a polymer matrix, and stirring to form foamed polymer slurry; wherein the foaming agent is lauryl magnesium sulfate, and the mass of the foaming agent accounts for 5.0 percent of that of the foamed polymer slurry; the foam stabilizer is polydimethylsiloxane and hydrated silicic acid, and the mass of the foam stabilizer accounts for 5.0% of that of the foamed polymer slurry; the polymer matrix is aqueous polyurethane emulsion, and the solid content is 20%; the stirring head used for stirring is a spiral blade stirring head, and the stirring time is 3.0 h.

3, S03, mixing: adding the conductive filler slurry obtained in the step S01 into the foamed polymer slurry obtained in the step S02, stirring and mixing, and carrying out secondary foaming to obtain mixed slurry; wherein the foamed polymer slurry accounts for 80% of the mass of the mixed slurry, the conductive filler slurry accounts for 20% of the mass of the mixed slurry, the stirring time is 0.5h, and the stirring head of a stirrer used for stirring is a spiral surface blade stirring head.

S04, coating the mixed slurry on a substrate through a coating process; wherein the coating process is a scraper coating process, the coating thickness is 7500 micrometers, and the substrate is a polyethylene terephthalate release film.

5, S05, drying: drying the coated material, and stripping the coated material from the substrate to obtain a porous elastic conductive composite film; wherein the drying mode comprises a bottom plate drying mode and a hot air drying mode, the bottom plate drying temperature is 40 ℃, 100 ℃ and 140 ℃, the hot air drying temperature is 180 ℃, and the drying time is 2 hours.

6. The porous elastic conductive composite film obtained through the steps S01-S05 has the thickness of 1.20mm, the resistivity of 42000 omega cm, the porosity of 78 percent and the compression rebound, and the compression ratio of 70 percent. FIG. 2 is a surface SEM photograph of the porous elastic conductive composite film prepared through the above steps. FIG. 3 is a SEM image of the cross section of the porous elastic conductive composite film obtained through the above steps.