Preparation method of lightweight conductive double-foam composite material and application thereof

Abstract

The present application relates to the technical field of organic silicon foamed material, and particularly relates to a preparation method of light double-foam composite material prepared by compounding liquid metal foam and organic silicon foamed glue and application thereof, and the light conductive double-foam composite material provided by the present application is composed of liquid metal foam and organic silicon foam cotton. The liquid metal foam is stirred and oxidized at room temperature, then is formed and foamed under high humidity and is subjected to surface modification treatment. The organic silicon foam cotton glue is composed of component A and component B, the component A includes the following raw materials in mass percentage: vinyl silicone oil, hydroxyl silicone oil, fumed white carbon black and Koster catalyst; the component B includes the following raw materials in mass percentage: vinyl silicone oil, hydrogen-containing silicone oil, fumed silica and 1-ethynylcyclohexanol. The light conductive organic silicon-liquid metal double-foam composite material with good interface performance prepared by the present application can be used as a high-sensitivity pressure sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone foamed materials, and particularly relates to a preparation method of a light-weight double-foam composite material prepared by compounding modified liquid metal foam and silicone foaming glue and application thereof. BACKGROUND

[0002] Liquid metal is a collective term for the seventeen metals that have a melting point not exceeding that 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℃). Liquid metals (LM) based on gallium have witnessed rapid commercial use. Due to the unique combination of metal properties and low melting, it is particularly suitable for sensing electronic devices. In addition, unlike other low-melting-point metals with health hazards, low-melting-point metal handling is relatively safe. Liquid metal foam, such kind of multiphase composite material, has a LM dominant continuous phase. Therefore, this LM matrix composite material has typical electrical conductivity, but shows very different flow behavior from LM itself, while LM itself has a bulk viscosity similar to water. Compared with LM, the use of LM composite material has better shape retention, which is very suitable for patterning techniques such as direct writing, shaping and templating based on extrusion.

[0003] Although a lot of achievements have been made in the research of liquid metal foam preparation, there are still some shortcomings, such as easy loss of electrical conductivity, poor adhesion between the substrate during compounding, and too large density of liquid metal and its composite material, which become one of the obstacles to the practical application of liquid metal composite material. The main chain of silicone material contains "silicon-oxygen-silicon" structure, and the side chain contains a small amount of organic groups, so it has the dual advantages of organic and inorganic materials, such as high and low temperature resistance, radiation resistance and weather resistance, hydrophobicity, physiological inertia, oil resistance, solvent resistance and other properties, which are unmatched by other materials. It is worth noting that the silicone foam has high elasticity like rubber, and also has sound insulation, shock absorption and other properties of foam materials, and is often used in shock pads, sealing pads, sound insulation materials, insulation materials, aviation thermal insulation materials and some other occasions with high requirements for material performance. On the other hand, benefiting from the rapid development of electronic devices and other fields, the demand for silicone materials is showing a steady growth trend. As a new green chemical material, the environmental protection and energy saving characteristics of the silicone industry make its market demand more prosperous.

[0004] Based on the above analysis, a preparation method of a light-weight conductive double-foam composite material prepared by compounding modified liquid metal foam and silicone foaming glue is provided, which has important significance for green application in the field of flexible electronics and other fields. SUMMARY

[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. It not only solves the mechanical hardening and electrical performance attenuation of existing liquid metal foam under humid conditions in the related art, and overcomes the high density problem of liquid metal itself to a certain extent, but also improves the interfacial adhesion between 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. The composite material is completely formed.

[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 embodiments, the liquid metal is composed of a bimetallic material of gallium and indium, with a mass fraction ratio of Ga:In ranging from 1:1 to 100:1, preferably from 6:4 to 19:1.

[0009] In some embodiments, the room-temperature foaming silicone foam comprises component A and component B. Component A comprises the following raw materials in parts by weight: 30-80 parts vinyl silicone oil, 5-25 parts low-viscosity hydroxyl silicone oil, 1-20 parts fumed silica, and 0.01-0.1 parts platinum catalyst. Component B comprises the following raw materials in parts by weight: 30-80 parts vinyl silicone oil, 1-30 parts hydrogenated silicone oil, 1-20 parts fumed silica, and 0.001-0.1 parts 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 ethynylcyclohexanol.

[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 for 1 day at 100% relative humidity 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:

[0014] Preparation of component A: Prepare by compounding vinyl silicone oil, low-viscosity hydroxy silicone oil, fumed silica, and platinum catalyst, and mix them evenly with a high-speed disperser to obtain component A;

[0015] Preparation of component B: Prepare by compounding vinyl silicone oil, hydrogenated silicone oil, fumed silica and inhibitor, and mix them evenly with a high-speed disperser to obtain component B;

[0016] Mixing: Mix component A and component B in a mass ratio of 1:1.

[0017] In some embodiments, the viscosity of component A is 2000-5000 cps, and the viscosity of component B is 2000-6000 cps.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] In a third aspect, the present invention further provides applications of the aforementioned lightweight conductive double foam composite material in the fields of conductive and pressure sensor devices.

[0023] 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 when combined 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.

[0024] The beneficial effects of the technical solution provided by this application include:

[0025] 1. This application can utilize modified liquid metal foaming to construct a multiphase liquid metal foam, combined with 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 lightweight conductive composite material combining liquid metal foam and silicone foam.

[0026] 2. The liquid metal-organic silicone foam composite material provided in this application not only solves the mechanical hardening and electrical performance degradation issues of liquid metal foam in humid conditions, but also overcomes the high density issues of liquid metal and its composite systems to a certain extent. Furthermore, the surface modification of the liquid metal foam also imparts favorable interfacial interactions to the composite material. This lightweight, highly conductive organosilicon-liquid metal dual foam composite material can be used in practical applications as a conductive and pressure sensor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

[0028] Figure 1 This 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

[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] The embodiments of the present application provide 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 such as the electrical conductivity of existing silicone foam, the weak interfacial adhesion between liquid metal and silicone, the mechanical hardening of liquid metal foam under humid conditions, the attenuation of electrical properties, and high density that cannot be met simultaneously.

[0031] The present invention provides a method for preparing a lightweight dual-conductive foam composite material prepared by compounding modified liquid metal foam and silicone foam, comprising the following steps:

[0032] Liquid metal foam modification: Gallium-indium alloy (Ga:In = 75.5:24.5 by mass) was dispersed using an impeller under shearing and stirring at 250 rpm for 1-2 hours at room temperature. The dispersed liquid metal was then mixed with 10 wt% deionized water using a planetary mixer for 1-5 minutes. Finally, the foam was grown in a sealed storage chamber at 100% relative humidity for one day before being surface-treated with 3-(trimethoxysilyl)propyl methacrylate.

[0033] 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.

[0034] Prepare component A: by weight, mix 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 to obtain component A;

[0035] 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.

[0036] 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 mass fraction of 1:1, with the mass fraction relative to 1 part of 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.

[0037] The following describes in detail 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 combination with examples and comparative examples.

[0038] Example 1:

[0039] Modified liquid metal foam was prepared by shear-dispersing a gallium-indium alloy (Ga:In = 75.5:24.5 by mass) using an impeller and stirring at 250 rpm for 1 hour at room temperature. The dispersed liquid metal was then mixed with 10 wt% deionized water using a planetary mixer for 1 minute. The foam was then grown in a sealed storage chamber at 100% relative humidity for one day before being surface-treated with 3-(trimethoxysilyl)propyl methacrylate.

[0040] Preparation of Component A: By weight, 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 to obtain Component A with a viscosity of 4300 cps.

[0041] Prepare component B by mixing, by weight, 75 parts 2000 cps vinyl silicone oil, 10 parts hydrogenated silicone oil (1% hydrogen content), 15 parts fumed silica, and 0.1 parts 2-methyl-3-butyn-2-ol to obtain component B with a viscosity of 3500 cps.

[0042] Preparation of conductive double foam composite material: 50g of modified liquid metal foam was placed in a mold, 10g of component A and component B were mixed evenly in a 1:1 mass ratio, the two-component silicone 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.

[0043] Example 2:

[0044] The only difference between Example 2 and Example 1 is that the water mixing time is changed from 1 min to 5 min.

[0045] Example 3:

[0046] 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.

[0047] Example 4:

[0048] 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.

[0049] Example 5:

[0050] The only difference between Example 5 and Example 1 is that the mass ratio of liquid metal gallium to indium is 79:21.

[0051] Example 6:

[0052] Example 6 differs from Example 5 only in that the surface modifier is vinyltriethoxysilane.

[0053] Example 7:

[0054] Example 7 differs from Example 5 only in that the surface modifier is trimethoxy[3-(methylamino)propyl]silane).

[0055] Example 8:

[0056] The only difference between Example 8 and Example 1 is that the mass ratio of liquid metal gallium to indium is 95:5.

[0057] Comparative Example 1:

[0058] 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%.

[0059] Comparative Example 2:

[0060] Comparative Example 2 differs from Example 1 only in that the liquid metal is not surface treated.

[0061] Comparative Example 3:

[0062] Comparative Example 3 is different from Example 1 only in that the surface modifier is glycidyloxypropyltrimethoxysilane

[0063] Table 1: Performance test results of lightweight conductive double foam composite materials prepared in Examples 1-12 and Comparative Examples 1-2

[0064]

[0065] 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.

[0066] The less water, the shorter the mixing time, and the slower the stirring, the less foamed, insulating, and oxidized crust the composite material will have, resulting in a higher density and relatively lower resistance. Liquid metals with targeted surface treatments all bonded well with the silicone surface, indicating that the modified liquid metal material is relatively more stable.

[0067] The density of the product using the technical solution of the present invention is less than 2.2 g / cm 3 , more preferably the density is less than 2.0 g / cm 3 , more preferably the density is less than 1.8g / cm 3 , more preferably the density is less than 1.7g / cm 3 .

[0068] 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" 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 expressions 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 an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0069] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising 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 further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0070] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing a conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam, characterized in that: The following steps are involved: (1) Modified liquid metal foam The metal material is sheared and dispersed, and stirred at a speed of 100-300 rpm / min for 1-3 hours at room temperature to obtain liquid metal; the dispersed liquid metal is then mixed with 1%-10wt% deionized water using a planetary mixer for 1-30 minutes, and foamed at 100% relative humidity for 20-24 hours to obtain a conductive double foam composite material prepared by compounding the liquid metal foam and the silicone foam after treatment with a silane coupling agent, wherein the silane coupling agent is selected from any one of vinyltriethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, and trimethoxy[3-(methylamino)propyl]silane; the metal material is an alloy composed of two or more of gallium Ga, indium In, tin Sn, and zinc Zn metals; and the mass ratio of the modified liquid metal foam to the silicone foam is 5:1 to 15:1; (2) Silicone foam is infiltrated into the pore structure of the modified liquid metal foam, and the composite material is fully formed after foaming at room temperature.

2. 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 metal material consists of gallium and indium bimetallic materials; the mass fraction ratio of Ga:In is 50:50-100:

1.

3. 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 mass fraction ratio of Ga:In is 60:40-90:

10.

4. 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 stirring time is 1-2 hours at a rotation speed of 250 rpm / min under room temperature.

5. 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 silicone foam includes component A and component B. Component A includes 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 includes 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; the mass ratio of component A to component B is 1:

1.

6. 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: Silicone foam is prepared through the following process: Preparation of component A: Prepare by compounding vinyl silicone oil, low-viscosity hydroxy silicone oil, fumed silica, and platinum catalyst, and mix them evenly with a high-speed disperser to obtain component A; Preparation of component B: Prepare by compounding vinyl silicone oil, hydrogenated silicone oil, fumed silica and inhibitor, and mix 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.

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 mass ratio of the modified liquid metal foam to the organic silicon foam is 5:1-7:

1.

8. The method for preparing the conductive double foam composite material prepared by compounding liquid metal foam and organic silicon foam according to any one of claims 1 to 7, characterized in that: The conductive double-foam composite material prepared by combining liquid metal foam and silicone foam is prepared by the following process: the liquid metal foam is surface-modified, and then the modified liquid metal foam is cleaned and placed in a mold; the silicone foam is injected into the mold, allowed to stand, and foamed at room temperature to obtain the conductive double-foam composite material.

9. Conductive double foam composite material, characterized in that, The method according to any one of claims 1 to 8 is used for preparation.

10. Use of the conductive double foam composite material according to claim 9 in conductive and pressure sensors.

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