Multilayer conductive foam and preparation method thereof

Abstract

The invention relates to the technical field of foam materials, in particular to multilayer conductive foam and a preparation method thereof. The multi-layer conductive foam comprises a foam core layer, an adhesive layer and a conductive fabric outer layer from inside to outside, the foam core layer comprises the following materials in parts by weight: 60-70 parts of polyester polyol, 20-30 parts of expansible graphite, 30-40 parts of isocyanate, 2-5 parts of a foaming agent, 2-3 parts of a foam stabilizer, 14-16 parts of filler, 1-2 parts of an antioxidant, 0.5-1 part of a dispersing agent and 0.5-1 part of a catalyst. The foam material obtained by the preparation method disclosed by the invention not only has excellent conductivity, but also can keep stable flame retardant property. The multilayer conductive foam has a wide application prospect in the fields of electronic communication, medical equipment, aerospace, transportation and the like, especially in the emerging fields of new energy automobiles, 5G communication, Internet of Things and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of foam materials, and particularly to a multi-layer conductive foam and a preparation method thereof. Background Art

[0002] In the rapidly developing electronics industry, conductive foam, as a material with both conductivity and flexibility, is widely used in electronic devices for electromagnetic shielding, grounding connection, and thermal management. However, although the existing conductive foam technology has to a certain extent met the market demand, there are still many challenges in the preparation process, performance stability, and environmental friendliness. Especially with the rise of emerging technologies such as 5G communication, the Internet of Things, and wearable devices, the performance requirements for conductive foam are increasing day by day, prompting us to develop an improved multi-layer conductive foam and an innovative preparation method.

[0003] Patent CN111016349B provides a flame-retardant and weather-resistant conductive foam. The flame-retardant and weather-resistant conductive foam has a three-layer structure, which is a polyimide conductive fabric, a flame-retardant hot melt adhesive, and a flame-retardant foam core layer from the outside to the inside. The polyimide conductive fabric is a plain fabric made of polyimide fibers along the radial direction of the conductive foam and metal-plated polyimide fibers along the circumferential direction of the cross-section of the conductive foam. The flame-retardant and weather-resistant conductive foam prepared by the present invention has a flame-retardant rating of UL94 HF-1. After forming a dense outer and porous inner carbonized layer under the flame, it extinguishes, effectively preventing the spread of the flame. There is no melting drop and no swelling under the flame, and it will not cause pollution and extrusion to the device, and can provide effective protection for the device.

[0004] In order to improve the flame-retardant performance of conductive foam, some methods have been adopted in the prior art, such as surface modification, superfine grinding, compounding synergism, crosslinking, microencapsulation, and nano flame retardancy. These methods have improved the flame-retardant performance of conductive foam to a certain extent, but there are still some deficiencies. For example, although surface modification can improve the adhesion between the flame retardant and the polymer, the treatment process is complex and the cost is high; although superfine grinding and compounding synergism can enhance the flame-retardant effect, they may have a negative impact on other properties of the conductive foam; although crosslinking and microencapsulation can improve the stability and compatibility of the flame retardant, the preparation process is complex and difficult to control. Based on this, the present invention proposes a multi-layer conductive foam and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-layer conductive foam and a preparation method thereof, which can significantly improve the flame-retardant performance while maintaining the conductive performance.

[0006] In a first aspect, the present invention provides a multi-layer conductive foam, comprising a foam core layer, an adhesive layer and a conductive fabric outer layer from the inside out; the foam core layer comprises the following materials in parts by weight: 60-70 parts of polyester polyol, 20-30 parts of expandable graphite, 30-40 parts of isocyanate, 2-5 parts of foaming agent, 2-3 parts of foam stabilizer, 14-16 parts of filler, 1-2 parts of antioxidant, 0.5-1 part of dispersant, 0.5-1 part of catalyst.

[0007] Further, the preparation method of the foam core layer comprises: sequentially adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, catalyst into a stirrer, stirring at a speed of 400-500 r / min for 100-120 min to ensure thorough mixing; subsequently, rapidly adding isocyanate to the mixture, carrying out high-speed stirring at a speed of 1200-1300 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 5-10 min, transferring the mold filled with the mixture to a curing furnace, and carrying out curing treatment at a temperature of 110-112 °C for 5-6 h to prepare the foam core layer.

[0008] Further, the hydroxyl value of the polyester polyol is 420-440 mg KOH / g.

[0009] Further, the filler comprises Nb 2 O 5 @ZnO and Mg(OH) 2 。

[0010] Further, the preparation method of the Nb 2 O 5 @ZnO comprises: adding Nb 2 O 5 to ethanol, stirring and dispersing for 30-40 min, then adding zinc nitrate and continuing to stir for 10-12 min, continuing to stir and adding an aqueous NaOH solution at a temperature of 50-60 °C, continuing to stir at a temperature of 75-85 °C for 100-120 min, centrifuging, washing with water and drying, calcining at a temperature of 350-360 °C for 30-40 min, heating to 410-420 °C and continuing to calcine for 30-40 min and then cooling to obtain the Nb 2 O 5 @ZnO nanocomposite.

[0011] Further, the mass concentration of the aqueous NaOH solution is 20%; the Nb 2 O 5The weight ratios of ethanol, zinc nitrate and NaOH aqueous solution are (26-27): (130-140): (18-20): (35-45).

[0012] Furthermore, the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; and the catalyst is dibutyltin dilaurate.

[0013] Furthermore, the adhesive layer includes tesa60210 or tesa60249.

[0014] Furthermore, the outer layer of the conductive fabric includes polyimide fibers as weft fibers and metal-plated polyimide fibers as radial fibers, and is made according to a plain weave method; wherein the metal layer thickness of the metal-plated polyimide fibers is 0.5-0.7 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0015] In a second aspect, the present invention provides a method for preparing a multi-layer conductive foam, the steps comprising: preparing a foam core layer and a conductive fabric outer layer, compositely compacting the foam core layer and the conductive fabric outer layer through an adhesive layer, and performing high-temperature treatment at a temperature of 110-115°C for 20-30 minutes to obtain the multi-layer conductive foam.

[0016] The beneficial effects of the present invention are: The present invention relates to a multi-layer conductive foam formula, which uses expandable graphite and fillers to improve flame retardancy and maintain the conductive properties of the material. Expandable graphite will expand rapidly at high temperatures to form a dense carbonized layer, which effectively isolates oxygen and heat, thereby preventing the spread of flames. Mg(OH) 2 It can decompose at high temperatures to produce water vapor, which can dilute the concentration of combustible gases around the burning object, thereby inhibiting combustion. At the same time, water vapor can also take away a large amount of heat and reduce the temperature of the combustion area. 2 O 5 @ZnO can also form a stable oxide layer at high temperature. These oxide layers have certain thermal insulation and barrier effects, which can prevent the transfer of heat and oxygen. They can also prevent the material from being degraded due to oxidation during processing and use, thereby improving the thermal stability and flame retardancy of the material.

[0017] In addition, Nb 2 O 5 @ZnO has high thermal stability, can maintain structural stability at high temperatures, and is not easy to decompose and produce combustible gases. 2 O 5@As a kind of nanoparticle, ZnO can fill the voids and defects in graphite. Its addition can improve the thermal stability of expandable graphite, making graphite not easily burn or decompose at high temperatures. When combustion occurs, expandable graphite will rapidly expand to form a carbon layer, while Mg(OH) 2 and Nb 2 O 5 @The decomposition products of ZnO will fill the voids in the carbon layer, further enhancing the density and heat insulation of the carbon layer. These decomposition products may also chemically react with the carbon element in the carbon layer to form more stable compounds, thereby further improving the flame retardancy of the carbon layer.

[0018] Mg(OH) 2 and Nb 2 O 5 @The addition of ZnO can increase the inorganic matter content in the carbon layer. These inorganic matters can enhance the strength and stability of the carbon layer, preventing the carbon layer from cracking or falling off during combustion. Through a reasonable compounding ratio, a denser and more uniform structure can be formed in the carbon layer, improving the morphology of the carbon layer. This structure is beneficial to blocking the transfer of oxygen and heat, thereby improving the flame retardancy.

[0019] On this basis, the addition of Mg(OH) 2 and Nb 2 O 5 @ZnO can further affect the flame retardancy effect of expandable graphite. Specific embodiments

[0020] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0021] Example 1 This example provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 25 parts of expandable graphite, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, and 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: successively adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring for 110 min under the condition of a rotation speed of 450 r / min to ensure sufficient mixing; subsequently, rapidly adding isocyanate to the mixture, carrying out high-speed stirring under the condition of a rotation speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and carrying out curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler includes Nb with a weight ratio of 2:1 2 O 5 @ZnO and Mg(OH) 2 ; The preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5 to ethanol and stirring for dispersion for 35 min, then adding zinc nitrate and continuing to stir for 11 min, continuing to stir and adding an aqueous NaOH solution under the condition of a temperature of 55 °C, continuing to stir for 110 min under the condition of a temperature of 80 °C, centrifuging, washing with water and drying, calcining at a temperature of 355 °C for 35 min, heating to 415 °C and continuing to calcine for 35 min and then cooling to obtain the Nb 2 O 5 @ZnO nanocomposite material; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of the Nb 2 O 5 , ethanol, zinc nitrate and the aqueous NaOH solution is 26.5:135:19:40.

[0022] Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0023] Among them, the conductive fabric outer layer is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; among them, the metal layer thickness of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0024] In this embodiment, a method for preparing a multi-layer conductive foam is further provided. The steps include: preparing a foam core layer and a conductive fabric outer layer, laminating and compressing the foam core layer and the conductive fabric outer layer through an adhesive layer, and performing a high-temperature treatment at a temperature of 112 °C for 25 minutes to obtain a multi-layer conductive foam.

[0025] Example 2 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 64 parts of polyester polyol, 24 parts of expandable graphite, 34 parts of isocyanate, 3 parts of foaming agent, 2 parts of foam stabilizer, 15 parts of filler, 1 part of antioxidant, 0.5 part of dispersant, and 0.5 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 400 r / min for 100 minutes to ensure sufficient mixing; subsequently, quickly adding isocyanate to the mixture, performing high-speed stirring at a speed of 1200 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 5 minutes, transferring the mold filled with the mixture to a curing furnace, and performing a curing treatment at a temperature of 110 °C for 5 hours to prepare a foam core layer; Among them, the filler includes Nb 2 O 5 @ZnO and Mg(OH) 2 ; the preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5 to ethanol and stirring for dispersion for 30 minutes, then adding zinc nitrate and continuing to stir for 10 minutes, continuing to stir and adding an aqueous NaOH solution at a temperature of 50 °C, continuing to stir at a temperature of 75 °C for 100 minutes, centrifuging, washing with water, and drying, calcining at a temperature of 350 °C for 30 minutes, raising the temperature to 410 °C and continuing to calcine for 30 minutes and then cooling to obtain the Nb 2 O 5 @ZnO nanocomposite; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of the Nb 2 O 5 , ethanol, zinc nitrate, and aqueous NaOH solution is 26:132:19:38.

[0026] Among them, the hydroxyl value of the polyester polyol is 420 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0027] Among them, the outer layer of the conductive fabric is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.5 μm, and the metal layer is a copper-nickel alloy of 3:7.

[0028] In this embodiment, a preparation method of a multi-layer conductive foam is also provided, and the steps include: preparing a foam core layer and an outer layer of a conductive fabric, compounding and compacting the foam core layer and the outer layer of the conductive fabric through an adhesive layer, and performing high-temperature treatment at 110 °C for 30 min to obtain a multi-layer conductive foam.

[0029] Example 3 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and an outer layer of a conductive fabric from the inside out; the foam core layer includes the following materials in parts by weight: 68 parts of polyester polyol, 27 parts of expandable graphite, 36 parts of isocyanate, 4 parts of foaming agent, 3 parts of foam stabilizer, 16 parts of filler, 2 parts of antioxidant, 1 part of dispersant, and 1 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 500 r / min for 120 min to ensure thorough mixing; subsequently, quickly adding isocyanate to the mixture, performing high-speed stirring at a speed of 1300 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 10 min, and transferring the mold filled with the mixture to a curing furnace for curing treatment at 112 °C for 6 h to prepare the foam core layer; Among them, the filler includes Nb 2 O 5 @ZnO and Mg(OH) 2 ; the preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5Disperse it in ethanol and stir for 40 min. Then add zinc nitrate and continue stirring for 12 min. Under the condition of a temperature of 60 °C, continue stirring and add an aqueous NaOH solution. Under the condition of a temperature of 85 °C, continue stirring for 120 min. After centrifugation, wash with water and dry. Calcinate at a temperature of 360 °C for 40 min. After heating to 420 °C, continue calcining for 40 min and then cool to obtain Nb 2 O 5 @ZnO nanocomposite; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of the Nb 2 O 5 , ethanol, zinc nitrate and the aqueous NaOH solution is 27:135:19:42.

[0030] Among them, the hydroxyl value of the polyester polyol is 440 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60249.

[0031] Among them, the outer layer of the conductive fabric is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.7 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0032] In this embodiment, a preparation method of a multi-layer conductive foam is further provided. The steps include: preparing a foam core layer and an outer conductive fabric layer, and laminating and compacting the foam core layer and the outer conductive fabric layer through an adhesive layer, and performing high-temperature treatment at a temperature of 115 °C for 30 min to obtain a multi-layer conductive foam.

[0033] Example 4 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer and an outer conductive fabric layer from the inside out; the foam core layer includes the following materials in parts by weight: 70 parts of polyester polyol, 30 parts of expandable graphite, 40 parts of isocyanate, 5 parts of foaming agent, 3 parts of foam stabilizer, 16 parts of filler, 2 parts of antioxidant, 1 part of dispersant, 1 part of catalyst; Among them, the preparation method of the foam core layer includes: successively adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring for 110 min at a rotation speed of 450 r / min to ensure thorough mixing; subsequently, rapidly adding isocyanate to the mixture, carrying out high-speed stirring at a rotation speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold containing the mixture to a curing furnace, and carrying out curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler includes Nb with a weight ratio of 2:1 2 O 5 @ZnO and Mg(OH) 2 ; The preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5 to ethanol and stirring for dispersion for 35 min, then adding zinc nitrate and continuing to stir for 11 min, continuing to stir and adding an aqueous NaOH solution at a temperature of 55 °C, continuing to stir at a temperature of 80 °C for 110 min, centrifuging, washing with water, and drying, calcining at a temperature of 355 °C for 35 min, heating to 415 °C and continuing to calcine for 35 min and then cooling to obtain Nb 2 O 5 @ZnO nanocomposite; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of Nb 2 O 5 , ethanol, zinc nitrate, and aqueous NaOH solution is 26.5:135:19:40.

[0034] Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0035] Among them, the conductive fabric outer layer is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0036] In this embodiment, a method for preparing a multi-layer conductive foam is also provided. The steps include: preparing a foam core layer and a conductive fabric outer layer, compounding and pressing the foam core layer and the conductive fabric outer layer through an adhesive layer, and performing a high-temperature treatment at a temperature of 112 °C for 25 min to obtain the multi-layer conductive foam.

[0037] Comparative Example 1 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 25 parts of expandable graphite, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, and 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 450 r / min for 110 min to ensure sufficient mixing; subsequently, quickly adding isocyanate to the mixture, performing high-speed stirring at a speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold containing the mixture to a curing furnace, and performing a curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler includes Nb with a weight ratio of 2:1 2 O 5 and Mg(OH) 2 ; Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0038] Among them, the conductive fabric outer layer is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0039] In this embodiment, a method for preparing a multi-layer conductive foam is also provided. The steps include: preparing a foam core layer and a conductive fabric outer layer, compounding and pressing the foam core layer and the conductive fabric outer layer through an adhesive layer, and performing a high-temperature treatment at a temperature of 112 °C for 25 min to obtain the multi-layer conductive foam.

[0040] Comparative Example 2 This example provides a multi - layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 25 parts of expandable graphite, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 450 r / min for 110 min to ensure full mixing; subsequently, quickly adding isocyanate to the mixture, carrying out high - speed stirring at a speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and carrying out curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler includes ZnO and Mg(OH) with a weight - ratio of 2:1 2 ; Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0041] Among them, the conductive fabric outer layer is made by using polyimide fiber as the weft fiber and metal - plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal - plated polyimide fiber is 0.6 μm, and the metal layer is a 3:7 copper - nickel alloy.

[0042] This example also provides a preparation method of a multi - layer conductive foam, and the steps include: preparing a foam core layer and a conductive fabric outer layer, compounding and compacting the foam core layer and the conductive fabric outer layer through the adhesive layer, and obtaining a multi - layer conductive foam after high - temperature treatment at a temperature of 112 °C for 25 min.

[0043] Comparative Example 3 This example provides a multi - layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 25 parts of expandable graphite, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer in sequence, stirring for 110 min under the condition of a rotation speed of 450 r / min to ensure sufficient mixing; subsequently, rapidly adding isocyanate to the mixture, performing high-speed stirring under the condition of a rotation speed of 1250 r / min, pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and performing curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler is Mg(OH) 2 ; Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0044] Among them, the outer layer of the conductive fabric is prepared by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the radial fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a copper-nickel alloy of 3:7.

[0045] In this embodiment, a preparation method of a multi-layer conductive foam is further provided. The steps include: preparing a foam core layer and an outer layer of a conductive fabric, compounding and compacting the foam core layer and the outer layer of the conductive fabric through an adhesive layer, and performing high-temperature treatment at a temperature of 112 °C for 25 min to obtain a multi-layer conductive foam.

[0046] Comparative Example 4 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and an outer layer of a conductive fabric from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 25 parts of expandable graphite, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, and 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer in sequence, stirring for 110 min under the condition of a rotation speed of 450 r / min to ensure sufficient mixing; subsequently, rapidly adding isocyanate to the mixture, performing high-speed stirring under the condition of a rotation speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and performing curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler is Nb 2 O 5 @ZnO; the preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5 to ethanol and stirring for dispersion for 35 min, then adding zinc nitrate and continuing to stir for 11 min, continuing to stir and adding an aqueous NaOH solution under the condition of a temperature of 55 °C, continuing to stir under the condition of a temperature of 80 °C for 110 min, centrifuging, washing with water, and drying, calcining at a temperature of 355 °C for 35 min, heating to 415 °C and continuing to calcine for 35 min, and then cooling to obtain the Nb 2 O 5 @ZnO nanocomposite; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of the Nb 2 O 5 , ethanol, zinc nitrate, and the aqueous NaOH solution is 26.5:135:19:40.

[0047] Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0048] Among them, the outer layer of the conductive fabric is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a copper-nickel alloy with a ratio of 3:7.

[0049] In this embodiment, a method for preparing a multi-layer conductive foam is further provided. The steps include: preparing a foam core layer and a conductive fabric outer layer, and laminating and compacting the foam core layer and the conductive fabric outer layer through an adhesive layer, and then performing a high-temperature treatment at 112 °C for 25 min to obtain the multi-layer conductive foam.

[0050] Comparative Example 5 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer, and a conductive fabric outer layer from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, and 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 450 r / min for 110 min to ensure thorough mixing; subsequently, quickly adding isocyanate to the mixture, performing high-speed stirring at a speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and performing a curing treatment at 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler includes Nb 2 O 5 @ZnO and Mg(OH) 2 ; the preparation method of the Nb 2 O 5 @ZnO includes: adding Nb 2 O 5 to ethanol and stirring for dispersion for 35 min, then adding zinc nitrate and continuing to stir for 11 min, continuing to stir and adding an aqueous NaOH solution at 55 °C, continuing to stir at 80 °C for 110 min, centrifuging, washing with water, and drying, calcining at 355 °C for 35 min, heating to 415 °C and continuing to calcine for 35 min and then cooling to obtain the Nb 2 O 5 @ZnO nanocomposite; the mass concentration of the aqueous NaOH solution is 20%; the weight ratio of Nb 2 O 5 , ethanol, zinc nitrate, and aqueous NaOH solution is 26.5:135:19:40.

[0051] Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0052] Among them, the outer layer of the conductive fabric is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the radial fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a 3:7 copper-nickel alloy.

[0053] This embodiment also provides a method for preparing a multi-layer conductive foam, the steps including: preparing a foam core layer and an outer layer of a conductive fabric, compounding and compacting the foam core layer and the outer layer of the conductive fabric through an adhesive layer, and performing a high-temperature treatment at a temperature of 112 °C for 25 min to obtain a multi-layer conductive foam.

[0054] Comparative Example 6 This embodiment provides a multi-layer conductive foam, including a foam core layer, an adhesive layer and an outer layer of a conductive fabric from the inside out; the foam core layer includes the following materials in parts by weight: 65 parts of polyester polyol, 35 parts of isocyanate, 3.5 parts of foaming agent, 2.5 parts of foam stabilizer, 15 parts of filler, 1.5 parts of antioxidant, 0.75 part of dispersant, 0.75 part of catalyst; Among them, the preparation method of the foam core layer includes: sequentially adding polyester polyol, foaming agent, foam stabilizer, filler, antioxidant, dispersant, and catalyst into a stirrer, stirring at a speed of 450 r / min for 110 min to ensure thorough mixing; subsequently, quickly adding isocyanate to the mixture, performing high-speed stirring at a speed of 1250 r / min, and pouring this mixture into a foaming mold, completing the foaming process within 7.5 min, transferring the mold filled with the mixture to a curing furnace, and performing a curing treatment at a temperature of 111 °C for 5.5 h to prepare the foam core layer; Among them, the filler is Mg(OH) 2 ; Among them, the hydroxyl value of the polyester polyol is 435 mg KOH / g; the polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; the catalyst is dibutyltin dilaurate; the adhesive layer includes tesa60210.

[0055] Among them, the outer layer of the conductive fabric is made by using polyimide fiber as the weft fiber and metal-plated polyimide fiber as the warp fiber according to the plain weave method; the thickness of the metal layer of the metal-plated polyimide fiber is 0.6 μm, and the metal layer is a copper-nickel alloy with a ratio of 3:7.

[0056] In this embodiment, a preparation method of a multi-layer conductive foam is also provided. The steps include: preparing a foam core layer and an outer layer of conductive fabric, compounding and pressing the foam core layer and the outer layer of conductive fabric through an adhesive layer, and performing high-temperature treatment at 112 °C for 25 min to obtain a multi-layer conductive foam.

[0057] The multi-layer conductive foams prepared in Examples 1-4 and Comparative Examples 1-6 were tested. 1. UL94 horizontal burning test for flame retardancy of foam materials: Refer to the standard "Experimental Method for Combustion Performance of Foamed Plastics - Horizontal Burning Method (GB / T 8332-2008)". 2. Volume resistivity: The volume resistivity was tested with reference to "Test Method for Surface Resistivity of Antistatic Properties of Clothing (GB / T 22042-2008)". 3. Flame retardancy of the foam core layer: The test was carried out with reference to "Plastics - Determination of Burning Behaviour by the Oxygen Index Method - Part 1: Guidelines (BT2406.1-2008)".

[0058] The test results are shown in Table 1.

[0059] Table 1 Test Results Flame retardant grade of foam Combustion phenomenon of foam Volume resistivity Limiting oxygen index of foam core layer Example 1 UL94 HF-1 Shrinks and carbonizes under the flame, forms a black carbon shell, and self-extinguishes 39 36 Example 2 UL94 HF-1 Shrinks and carbonizes under the flame, forms a black carbon shell, and self-extinguishes 39 36 Example 3 UL94 HF-1 Shrinks and carbonizes under the flame, forms a black carbon shell, and self-extinguishes 40 35 Example 4 UL94 HF-1 Shrinks and carbonizes under the flame, forms a black carbon shell, and self-extinguishes 41 36 Comparative example 1 UL94 HF-1 Does not self-extinguish inside, self-extinguishes after leaving the flame, volume expands slightly, and forms a black carbon shell 42 34 Comparative example 2 UL94 HF-2 Does not self-extinguish inside, self-extinguishes after leaving the flame, volume expands slightly, and forms a black carbon shell 44 32 Comparative example 3 UL94 HF-2 Does not self-extinguish inside, self-extinguishes after leaving the flame, volume expands, and forms a black carbon shell 47 30 Comparative example 4 UL94 HF-2 Does not self-extinguish inside, self-extinguishes after leaving the flame, volume expands slightly, and forms a black carbon shell 43 33 Comparative example 5 UL94 HF-2 Does not self-extinguish inside, self-extinguishes after leaving the flame, and forms a black carbon shell 46 31 Comparative example 6 UL94 HB Does not self-extinguish inside, and still burns slowly after leaving the flame 51 28 Finally, it should be noted that the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A multi-layer conductive foam, characterized in that: It includes a foam core layer, an adhesive layer and a conductive fabric outer layer from the inside to the outside; the foam core layer includes the following materials by weight: 60-70 parts of polyester polyol, 20-30 parts of expandable graphite, 30-40 parts of isocyanate, 2-5 parts of foaming agent, 2-3 parts of foam stabilizer, 14-16 parts of filler, 1-2 parts of antioxidant, 0.5-1 part of dispersant and 0.5-1 part of catalyst.

2. The multi-layer conductive foam according to claim 1, characterized in that: The preparation method of the foam core layer comprises: adding polyester polyol, expandable graphite, foaming agent, foam stabilizer, filler, antioxidant, dispersant and catalyst into a stirrer in sequence, stirring for 100-120 minutes at a rotation speed of 400-500 r / min to ensure that they are fully mixed; then, quickly adding isocyanate to the mixture, stirring at a high speed at a rotation speed of 1200-1300 r / min, pouring the mixture into a foaming mold, completing the foaming process within 5-10 minutes, transferring the mold containing the mixture to a curing furnace, and performing a curing treatment at a temperature of 110-112° C. for 5-6 hours to prepare the foam core layer.

3. The multi-layer conductive foam according to claim 1, characterized in that: The polyester polyol has a hydroxyl value of 420-440 mg KOH / g.

4. The multi-layer conductive foam according to claim 1, characterized in that: The filler includes Nb2O5@ZnO and Mg(OH)2 in a weight ratio of (4-6):(2-3).

5. The multi-layer conductive foam according to claim 4, characterized in that: The preparation method of Nb2O5@ZnO comprises: adding Nb2O5 to ethanol and stirring and dispersing for 30-40 minutes, then adding zinc nitrate and continuing stirring for 10-12 minutes, adding NaOH aqueous solution at a temperature of 50-60°C and continuing stirring for 100-120 minutes at a temperature of 75-85°C, washing and drying after centrifugation, calcining at a temperature of 350-360°C for 30-40 minutes, heating to 410-420°C and continuing calcining for 30-40 minutes, and then cooling to obtain the Nb2O5@ZnO nanocomposite material.

6. The multi-layer conductive foam according to claim 5, characterized in that: The mass concentration of the NaOH aqueous solution is 20%; the weight ratios of Nb2O5, ethanol, zinc nitrate and NaOH aqueous solution are (26-27): (130-140): (18-20): (35-45).

7. The multi-layer conductive foam according to claim 1, characterized in that: The polyester polyol is polyester polyol 400A; the isocyanate is diphenylmethane diisocyanate; the foaming agent is foaming agent 141b; the foam stabilizer is silicone oil; the antioxidant is antioxidant 1010; the dispersant is sodium hexametaphosphate; and the catalyst is dibutyltin dilaurate.

8. The multi-layer conductive foam according to claim 1, characterized in that: The adhesive layer includes tesa60210 or tesa60249.

9. The method for preparing a multi-layer conductive foam according to claim 1, characterized in that: The outer layer of the conductive fabric includes polyimide fibers as weft fibers and metal-plated polyimide fibers as radial fibers, and is made according to a plain weave method; wherein the metal layer thickness of the metal-plated polyimide fibers is 0.5-0.7 μm, and the metal layer is a 3:7 copper-nickel alloy.

10. A method for preparing the multi-layer conductive foam according to any one of claims 1 to 9, characterized in that the steps include: A foam core layer and a conductive fabric outer layer are prepared, the foam core layer and the conductive fabric outer layer are compositely compacted through an adhesive layer, and a multi-layer conductive foam is obtained after high-temperature treatment at a temperature of 110-115° C. for 20-30 minutes.