Preparation method and application of lightweight conductive dual-foam composite material

Abstract

The invention relates to the technical field of organic silicon foam materials, in particular to a preparation method and application of a light-weight double-foam composite material prepared by compounding liquid metal foam and organic silicon polystyrene foam, and the light-weight conductive double-foam composite material provided by the invention is composed of the liquid metal foam and organic silicon foam. The liquid metal foam is stirred and oxidized at the room temperature, then formed and foamed at high humidity and subjected to surface modification treatment. The organosilicone foam adhesive is composed of a component A and a component B. The component A comprises the following raw materials by mass percent: vinyl silicone oil, hydroxyl silicone oil, fumed silica and a Karst catalyst. The component B is prepared from the following raw materials in percentage by mass: vinyl silicone oil, hydrogen-containing silicone oil, fumed silica and 1-ethynyl cyclohexanol. The light conductive organic silicon-liquid metal double foam composite material with good interface performance is prepared and can be used as a high-sensitivity pressure sensor.

Description

Technical Field

[0001] The invention relates to the technical field of organic silicon foam materials, and in particular to a preparation method and application of a lightweight double-foam composite material prepared by compounding modified liquid metal foam and organic silicon foaming glue. Background Art

[0002] Liquid metal is a general term for seventeen metals whose melting point does not exceed the melting temperature of aluminum (660.37℃). They are mercury, cesium, gallium, rubidium, potassium, sodium, indium, lithium, tin, bismuth, thallium, cadmium, lead, zinc, antimony, magnesium, and aluminum. There are also many alloys that are liquid at room temperature or even at very low temperatures. For example, sodium potassium alloy (melting point -12.5℃). Gallium-based liquid metal (LM) has witnessed rapid commercial use. Due to the unique combination of metallic properties and low melting point, it is particularly suitable for sensing electronic devices. In addition, unlike other low-melting point metals that have health hazards, low-melting point metals are relatively safe to handle. Multiphase composites such as liquid metal foams have LM as the dominant continuous phase. Therefore, this LM matrix composite has typical conductivity but exhibits very different flow behavior from LM itself, which has a bulk viscosity similar to water. Compared with LM, the use of LM composites has better shape retention ability, which is very suitable for patterning techniques such as extrusion-based direct writing, molding and template.

[0003] Although a lot of achievements have been made in the preparation of liquid metal foam, most of them have the disadvantages of easy loss of conductivity, poor adhesion between the substrate and the liquid metal and its composite materials, which has become one of the obstacles to the practical application of liquid metal composite materials. The main chain of organosilicon materials contains a "silicon-oxygen-silicon" structure, and the side chain contains a small amount of organic groups. Therefore, it has the dual advantages of organic and inorganic materials, such as resistance to high and low temperatures, radiation and weather resistance, hydrophobicity, physiological inertness, oil resistance, and solvent resistance, which are unmatched by other materials. It is worth noting that organosilicon foam has the high elasticity of rubber and the sound absorption, sound insulation, shock absorption and buffering properties of foam materials. It is mostly used in shock pads, sealing pads, sound insulation materials, insulation materials, aviation insulation materials and other occasions with relatively high material performance requirements. On the other hand, benefiting from the rapid development of electronic devices and other fields, the demand for organosilicon materials has shown a steady growth trend. As a new green chemical material, the organosilicon industry has a more vigorous market demand due to its environmental protection and energy-saving characteristics.

[0004] Based on the above analysis, a method for preparing a lightweight conductive double foam composite material prepared by compounding modified liquid metal foam and silicone foam is provided, which is of great significance for green applications in the fields of flexible electronics and the like. Summary of the invention

[0005] The embodiments of the present application provide a method for preparing a lightweight double-foam composite material prepared by compounding modified liquid metal foam and silicone foam, and its application, which not only solves the mechanical hardening and electrical property attenuation of the existing liquid metal foam under humid conditions in the related technology, and overcomes the high density problem of the liquid metal itself to a certain extent, but also improves the interface adhesion between the liquid metal and silicone through interface modification means, giving the silicone foam good conductive properties and stability.

[0006] In the first aspect, the present application provides a lightweight conductive double foam composite material prepared by compounding modified liquid metal foam and silicone foam. The liquid metal is modified after foaming and shaping under high humidity conditions. The silicone foam is infiltrated into the pore structure of the liquid metal frame and foamed at room temperature to complete the formation of the composite material.

[0007] In some embodiments, the liquid metal is an alloy consisting of two or more of gallium Ga, indium In, tin Sn, and zinc Zn.

[0008] In some preferred cases, the liquid metal is composed of bimetallic materials of gallium and indium, and the mass fraction ratio of Ga:In is 1:1 to 100:1, preferably 6:4 to 19:1.

[0009] In some embodiments, the room temperature foaming silicone foam comprises component A and component B, 3. Component A comprises the following raw materials in parts by mass: 30-80 parts of vinyl silicone oil, 5-25 parts of low-viscosity hydroxy silicone oil, 1-20 parts of fumed silica, and 0.01-0.1 parts of platinum catalyst. Component B comprises the following raw materials in parts by mass: 30-80 parts of vinyl silicone oil, 1-30 parts of hydrogenated silicone oil, 1-20 parts of fumed silica, and 0.001-0.1 parts of inhibitor. The mass ratio of component A to component B is 1:1.

[0010] The inhibitor is one or more of 2-methyl-3-butyn-2-ol and ethynyl cyclohexanol.

[0011] In a second aspect, the present invention also provides a method for preparing a modified liquid metal foam, comprising the following steps: using an impeller to disperse a gallium-indium alloy by shearing, stirring at a certain speed at room temperature, and then using a planetary mixer to mix the dispersed liquid metal with deionized water, and finally growing it at 100% relative humidity for 1 day to form a foam, and performing surface treatment using a silane coupling agent.

[0012] In some embodiments, the mass ratio of the modified liquid metal foam to the silicone foam in the lightweight conductive double foam composite material is 5:1-12:1.

[0013] In some embodiments, the room temperature foaming silicone foam of the lightweight conductive double foam composite material is prepared by the following process: Preparation of component A: Vinyl silicone oil, low-viscosity hydroxy silicone oil, fumed silica, and platinum catalyst are compounded and mixed evenly with a high-speed disperser to obtain component A; Preparation of component B: compounding vinyl silicone oil, hydrogen silicone oil, fumed silica and inhibitor, and mixing them evenly with a high-speed disperser to obtain component B; Mixing: Mix component A and component B in a mass ratio of 1:1.

[0014] In some embodiments, the viscosity of the component A is 2000-5000 cps, and the viscosity of the component B is 2000-6000 cps.

[0015] In some embodiments, the lightweight conductive double foam composite material is prepared by the following process: placing silane-modified liquid metal foam in a mold, injecting silicone foam into the mold, letting it stand, and foaming at room temperature to obtain the lightweight conductive double foam composite material.

[0016] In some embodiments, the liquid metal foam preparation method has a rotation speed of 250 rpm / min and a stirring time of 1-2 h.

[0017] In some embodiments, the method for preparing the modified liquid metal foam is characterized in that the planetary mixer mixes the dispersed liquid metal with 1%-10wt% deionized water for 1-30 minutes. Preferably, the amount of deionized water is 10% and the mixing time is 1-10 minutes; The surface treatment agent is a silane coupling agent: vinyl triethoxysilane, 3-(trimethoxysilyl) propyl methacrylate, trimethoxy [3-(methylamino) propyl] silane, etc., preferably 3-(trimethoxysilyl) propyl methacrylate.

[0018] In a third aspect, the present invention also provides the application of the above-mentioned lightweight conductive double foam composite material in the field of conductive and pressure sensor devices.

[0019] This application combines liquid metal foaming molding with the outstanding hydrophobicity and excellent weather resistance of silicone foam through interface modification, overcoming the high-density characteristics of liquid metal and the defects of high specific gravity and weak interface adhesion of composite materials with silicone materials. It can effectively improve the conductivity and stability of the composite material, thereby showing outstanding conductive stability. Its green, environmentally friendly and simple preparation process realizes the preparation of lightweight conductive double foam composite materials, which is expected to be applied in fields such as flexible electronics.

[0020] The beneficial effects of the technical solution provided by this application include: 1. The present application can utilize modified liquid metal foaming to construct multiphase liquid metal foam, and combine the hydrophobicity and good weather resistance of silicone foam to give the silicone material conductive properties. Its green and environmentally friendly process realizes the preparation of a novel combination of liquid metal foam and silicone foam to form a lightweight conductive composite material.

[0021] 2. The liquid metal-organic silicon foam composite material provided by the present application not only solves the mechanical hardening and electrical performance attenuation of liquid metal foam under humid conditions, but also overcomes the high density problem of liquid metal and its composite system to a certain extent. At the same time, the surface modification of liquid metal foam also gives the composite material good interface interaction. This light-weight organic silicon-liquid metal double foam composite material with good conductivity can be used as a conductive and pressure sensor device for practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a schematic diagram of the preparation method of a double foam composite material prepared by compounding modified liquid metal foam and silicone foam according to Example 1 of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] The embodiment of the present application provides a method for preparing a lightweight dual-conductive foam composite material prepared by compounding modified liquid metal foam and silicone foam, so as to solve the problems in the related art that the conductivity of the existing silicone foam, the weak interface adhesion between liquid metal and silicone, the mechanical hardening of the liquid metal foam under humid conditions, the attenuation of electrical properties, high density, etc. cannot be met at the same time.

[0026] The present application provides a method for preparing a lightweight dual-conductive foam composite material prepared by compounding a modified liquid metal foam and an organic silicon foam, comprising the following steps: Liquid metal foam modification preparation: Gallium-indium alloy (mass fraction ratio of Ga: In = 75.5: 24.5) was dispersed by shearing with an impeller and stirred at 250 rpm for 1-2 hours at room temperature, and then the dispersed liquid metal was mixed with 10wt% deionized water for 1-5 minutes using a planetary mixer. Finally, it was grown for one day at 100% relative humidity in a sealed storage room and then surface treated with 3-(trimethoxymethylsilyl) propyl methacrylate.

[0027] The B component includes the following raw materials in parts by mass: the mass ratio of the A component to the B component is 1:1.

[0028] Preparation of component A: by weight, 30-80 parts of vinyl silicone oil, 5-25 parts of low-viscosity hydroxy silicone oil, 1-20 parts of fumed silica, and 0.01-0.1 parts of platinum catalyst are mixed uniformly to obtain component A; Preparation of component B: by mass, 30-80 parts of vinyl silicone oil, 1-30 parts of hydrogenated silicone oil, 1-20 parts of fumed silica, and 0.001-0.1 parts of inhibitor.

[0029] Preparation of lightweight conductive double foam composite materials: 5-7 parts of modified liquid metal foam are placed in a mold, component A and component B are evenly mixed in a 1:1 mass fraction, with the mass fraction being 1 part relative to liquid metal, the two-component silicone mixture is quickly poured on the liquid metal foam, and then naturally foamed at room temperature to obtain a lightweight double foam composite material prepared by compounding modified liquid metal foam and silicone foam.

[0030] The following is a detailed description of a method for preparing a lightweight double-foam composite material prepared by compounding a modified liquid metal foam and an organosilicon foam provided in the present application in conjunction with embodiments and comparative examples.

[0031] Embodiment 1: Preparation of modified liquid metal foam: Gallium-indium alloy (mass fraction ratio of Ga: In = 75.5: 24.5) was dispersed by shearing with an impeller and stirred at 250 rpm for 1 hour at room temperature, and then the dispersed liquid metal was mixed with 10wt% deionized water for 1 minute using a planetary mixer. Finally, it was grown for one day at 100% relative humidity in a sealed storage room and then surface treated with 3-(trimethoxysilyl) propyl methacrylate.

[0032] Preparation of component A: By mass, 70 parts of 1500 cps vinyl silicone oil, 10 parts of 50 cps hydroxyl silicone oil (hydroxyl content 4%), 20 parts of fumed silica, and 0.01 parts of platinum catalyst were mixed uniformly to obtain component A with a viscosity of 4300 cps; Preparation of component B: 75 parts by mass of 2000 cps vinyl silicone oil, 10 parts by mass of hydrogenated silicone oil (hydrogen content 1%), 15 parts by mass of fumed silica, and 0.1 parts by mass of 2-methyl-3-butyn-2-ol were mixed to obtain component B with a viscosity of 3500 cps. Preparation of conductive double foam composite materials: 50 g of modified liquid metal foam was placed in a mold, 10 g of component A and component B were evenly mixed in a 1:1 mass fraction, the two-component silica gel mixture was quickly poured on the liquid metal foam, and then naturally foamed at room temperature to obtain a lightweight double foam composite material prepared by compounding modified liquid metal foam and silicone foam.

[0033] Embodiment 2: The only difference between Example 2 and Example 1 is that the time of water mixing is changed from 1 min to 5 min.

[0034] Embodiment 3: The only difference between Example 3 and Example 1 is that the time for stirring and mixing the liquid metal is changed from 1 hour to 2 hours.

[0035] Embodiment 4: The only difference between Example 4 and Example 2 is that the time for stirring and mixing the liquid metal is changed from 1 hour to 2 hours.

[0036] Embodiment 5: The only difference between Example 5 and Example 1 is that the mass ratio of liquid metal gallium to indium is 79:21.

[0037] Embodiment 6: Example 6 differs from Example 5 only in that the surface modifier is vinyltriethoxysilane.

[0038] Embodiment 7: Example 7 differs from Example 5 only in that the surface modifier is trimethoxy[3-(methylamino)propyl]silane).

[0039] Embodiment 8: The only difference between Example 8 and Example 1 is that the mass ratio of liquid metal gallium to indium is 95:5.

[0040] Comparative Example 1: The only difference between Comparative Example 1 and Example 1 is that the mass fraction of water added to the liquid metal is changed from 10% to 0%.

[0041] Comparative Example 2: Comparative Example 2 differs from Example 1 only in that the liquid metal is not surface treated.

[0042] Comparative Example 3: Comparative Example 3 is different from Example 1 only in that the surface modifier is glycidyloxypropyl trimethoxysilane Table 1: Performance test results of lightweight conductive double foam composite materials prepared in Examples 1-12 and Comparative Examples 1-2

[0043] Note: Indalloy 60 (75.5:24.55), 15.7℃ is the solid-liquid coexistence point; Indalloy 77 (95:5) is liquid at 25℃ and solid at 15℃; Indalloy 60E (79:21) 15.7℃ is the solid-liquid coexistence point.

[0044] The less water, the shorter the water mixing time, and the slower the stirring, the less foamed insulating oxide crust of the composite material formed, the greater the subsequent density, and the relatively small resistance. The liquid metals with targeted surface treatment all bond well with the silicone surface, indicating that the modified liquid metal material is relatively more stable.

[0045] The density of the product using the technical solution of the present invention is less than 2.2 g / cm 3 , and more preferably the density is less than 2.0 g / cm 3 , and more preferably the density is less than 1.8 g / cm 3 , and more preferably the density is less than 1.7 g / cm 3 .

[0046] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0047] It should be noted that, in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically stipulated.

[0048] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam, characterized in that: The liquid metal is subjected to surface modification after foaming and shaping under high humidity conditions, and the organic silicone foam is infiltrated into the pore structure of the surface-modified liquid metal. After foaming at room temperature, the composite material is completely formed.

2. The conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam according to claim 1, characterized in that: The liquid metal is an alloy of two or more of gallium Ga, indium In, tin Sn, and zinc Zn, preferably a bimetal of gallium and indium; the mass fraction ratio of Ga:In is 50:50-100:1, preferably 60:40-90:

10.

3. The conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam according to claim 1, characterized in that: The silicone foam comprises component A and component B. Component A comprises the following raw materials in parts by mass: 30-80 parts of vinyl silicone oil, 5-25 parts of low-viscosity hydroxy silicone oil, 1-20 parts of fumed silica, and 0.01-0.1 parts of a platinum catalyst; component B comprises the following raw materials in parts by mass: 30-80 parts of vinyl silicone oil, 1-30 parts of hydrogenated silicone oil, 1-20 parts of fumed silica, and 0.001-0.1 parts of an inhibitor; and the mass ratio of component A to component B is 1:

1.

4. The conductive double foam composite material prepared by combining liquid metal foam and organic silicon foam according to any one of claims 1 to 3, characterized in that: The following steps are involved: The metal material is sheared and dispersed, stirred at a certain speed at room temperature, and then the dispersed liquid metal is mixed with deionized water using a planetary mixer, grown for 20-24 hours at 100% relative humidity for foaming, and finally treated with a silane coupling agent to obtain a modified liquid metal foam.

5. The method for preparing liquid metal foam according to claim 4, characterized in that: The stirring is carried out at room temperature at a rotation speed of 100-300 rpm / min for 1-3 h; preferably at a rotation speed of 250 rpm / min for 1-2 h.

6. The conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam according to claim 5, characterized in that: The silane coupling agent is selected from any one of vinyl triethoxysilane, 3-(trimethoxymethylsilyl)propyl methacrylate, and trimethoxy [3-(methylamino)propyl] silane; The mass ratio of the surface-modified liquid metal foam to the silicone foam is 5:1 to 15:1, and the preferred mass ratio is 5:1 to 7:

1.

7. The method for preparing the conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam according to claim 1, characterized in that: The room temperature foaming silicone foam is prepared by the following process: Preparation of component A: Vinyl silicone oil, low-viscosity hydroxy silicone oil, fumed silica, and platinum catalyst are compounded and mixed evenly with a high-speed disperser to obtain component A; Preparation of component B: compounding vinyl silicone oil, hydrogen silicone oil, fumed silica and inhibitor, and mixing them evenly with a high-speed disperser to obtain component B; Mixing: Mix component A and component B in a mass ratio of 1:

1.

8. The preparation method according to claims 1-7, characterized in that: The preparation process is as follows: liquid metal foam is subjected to surface modification treatment, and then the modified metal foam is cleaned and placed in a mold; silicone foam is injected into the mold, allowed to stand, and foamed at room temperature to obtain a conductive double foam composite material.

9. The preparation method according to claim 7, characterized in that: The planetary mixer mixes the dispersed liquid metal with 1%-10wt% deionized water for 1-30min; the surface treatment agent is a silane coupling agent: vinyl triethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, trimethoxy [3-(methylamino)propyl] silane, etc., preferably 3-(trimethoxysilyl)propyl methacrylate.

10. Use of the conductive double foam composite material according to any one of claims 1 to 6 or the conductive double foam composite material prepared by the preparation method according to any one of claims 7 to 9 in conductive and pressure sensors.

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