CN114763309A

CN114763309A - Heating element with net-shaped hole wall and preparation method and application thereof

Info

Publication number: CN114763309A
Application number: CN202110056997.2A
Authority: CN
Inventors: 王钰; 刘静静; 任富强
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2021-01-15
Filing date: 2021-01-15
Publication date: 2022-07-19

Abstract

The invention provides a reticular pore wall heating element and a preparation method and application thereof, wherein the reticular pore wall heating element comprises 0.5-15 parts by weight of modified nano carbon material, 30-90 parts by weight of silicate solid waste, 4-25 parts by weight of polyether polyol, 5-25 parts by weight of polyisocyanate, 0.5-5 parts by weight of silicone oil foam stabilizer, 0.1-1 part by weight of foaming agent and 0.01-2 parts by weight of catalyst. The heating element with the net-shaped hole wall provided by the invention has the advantages of high efficiency, slow heat dissipation, good heat preservation effect, simple preparation process, low cost and good application prospect.

Description

Heating element with net-shaped hole wall and preparation method and application thereof

Technical Field

The invention belongs to the field of new material preparation, particularly relates to a reticular pore wall heating element and a preparation method and application thereof, and particularly relates to a slow-heat-dissipation reticular pore wall heating element and a preparation method and application thereof.

Background

The electrothermal material is used as a clean and efficient electricity-heat conversion material and is widely applied to the fields of household heating, outdoor deicing, physiotherapy health care, defogging and defrosting and the like. With the development of society and economic progress, the existing electrothermal materials such as conductive carbon films are exposed to more and more disadvantages such as high cost, complex process, rapid heat dissipation and low efficiency.

The silicate solid waste refers to solid waste containing a large amount of oxides of silicon, aluminum, calcium, magnesium and iron and a small amount of sulfides in the industrial production process, and besides being used as a small amount of additives in the cement, filler and ceramic industries, the solid waste is not effectively utilized, the accumulation of the solid waste not only occupies the land, but also the escaped sulfides can pollute farmlands and water bodies, and the silicate solid waste is used as a raw material to prepare heating elements and is in a vacant state for being utilized in a large amount.

CN111411451A discloses a flexible graphene non-woven fabric heating material and a preparation method thereof, wherein the heating material is prepared by uniformly mixing graphene oxide powder and glass powder to obtain composite powder, heating and completely melting to obtain a liquid melt, adding the melt into a nitrogen-protected centrifugal machine provided with micropores, centrifuging at a high speed, throwing out, cooling to form filaments, winding to form a velvet shape, continuously leading out by a traction roller, pressing and shaping to obtain a composite, and then carrying out compression roller shaping and hydrazine hydrate reduction treatment on the composite. According to the graphene non-woven fabric heating material provided by the invention, the graphene oxide powder and the glass powder are spun by centrifugation in a melt state, and are directly formed into a fiber membrane shape by forming and reduction without nonwoven fabric again, so that the graphene non-woven fabric heating material has certain flexibility, high temperature resistance, ageing resistance, stable structure, good heating effect, simple preparation equipment and easily-controlled process, and is beneficial to large-scale production. But the prepared heating material has the defects of quick heat dissipation, high cost, complex process and the like.

CN1308263C discloses a porous ceramic heating element, which is prepared by adding 0.08-1.00 wt% of foaming agent into 99.00-99.92 wt% of mixture of inorganic material, binder, conductive material, curing agent, binder and dispersion medium. The porous ceramic heating element having such a composition has an effect of solidifying the entire structure by increasing the bonding force of the porous bubbles formed in the porous ceramic heating element. However, the average porosity of the prepared porous ceramic is only 48%, and the pore size is large, so that the material has the advantages of high heat dissipation speed and high power consumption.

The existing electric heating material has the problems of high cost, complex process, quick heat dissipation and low efficiency. Therefore, how to provide an electrothermal material with simple process, low cost, high efficiency and excellent heat preservation performance becomes a problem to be solved urgently.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a reticular pore wall heating element and a preparation method and application thereof, and particularly provides a reticular pore wall heating element with slow heat dissipation and a preparation method and application thereof. The heating element with the net-shaped hole wall provided by the invention has the advantages of high efficiency, slow heat dissipation, good heat preservation effect, simple preparation process, low cost and good application prospect.

In order to achieve the purpose, the invention adopts the following technical scheme:

according to a first aspect, the invention provides a reticular pore wall heating element, which comprises, by weight, 0.5-15 parts of a modified nano carbon material, 30-90 parts of silicate solid waste, 4-25 parts of polyether polyol, 5-25 parts of polyisocyanate, 0.5-5 parts of a silicone oil foam stabilizer, 0.1-1 part of a foaming agent and 0.01-2 parts of a catalyst.

Wherein, the modified nano carbon material can be 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts and the like, the silicate solid waste can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts or 90 parts and the like, the polyether polyol can be 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts or 25 parts and the like, the polyisocyanate can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts or 25 parts and the like, and the polyisocyanate can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 20, 21 parts and the like, 22 parts, 23 parts, 24 parts or 25 parts, etc., the silicone oil foam stabilizer may be present in an amount of 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, etc., the blowing agent may be present in an amount of 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts or 1 part, etc., the catalyst may be present in an amount of 0.01 parts, 0.02 parts, 0.03 parts, 0.05 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts or 2 parts, etc., but not limited to the above-recited values are not specifically recited, and the same values as those not recited above are applicable.

The net-shaped hole wall heating element with the specific components has high efficiency, slow heat dissipation and good heat preservation effect; the influence of the silicate solid waste on the environment can be reduced by adopting the silicate solid waste as a raw material, and meanwhile, the production cost is greatly reduced; the heating element with the reticular pore walls has a porous reticular structure by utilizing the polyether polyol and the polyisocyanate for foaming, and the modified nano carbon material can be uniformly distributed, so that the heating element with the reticular pore walls has the advantages of slow heat dissipation, high efficiency and good heat preservation effect, and meanwhile, the proportion of the specific polyether polyol and the polyisocyanate and the content of the modified nano carbon material can realize the accurate and controllable reticular pore wall structure without subsequent treatment.

Preferably, the reticular pore wall heating element comprises, by weight, 5-10 parts of a modified nano carbon material, 40-80 parts of silicate solid waste, 10-20 parts of polyether polyol, 10-20 parts of polyisocyanate, 1.5-4 parts of a silicone oil foam stabilizer, 0.3-0.7 part of a foaming agent and 0.5-1.5 parts of a catalyst.

Preferably, the modified nano carbon material is prepared by a preparation method comprising the following steps: mixing a nano carbon material with an organic polymer solution for grafting modification reaction, and then carrying out suction filtration, drying and scattering to obtain the modified nano carbon material.

The preparation method is simple to operate, and the modified nano carbon material can be quickly and conveniently prepared; meanwhile, the organic polymer is adopted to modify the nano-carbon material, so that the surface of the obtained modified nano-carbon material is bonded with high-reactivity groups such as hydroxyl groups or isocyanate groups, and the like, and can generate a cross-linking polymerization reaction with a polyurethane monomer obtained by foaming the organic polymer, thereby realizing the construction of a mesh hole wall.

Preferably, the nanocarbon material comprises any one of graphene, carbon nanotubes or conductive nanocarbon black.

Preferably, the graphene has a sheet diameter of 1-10 μm and a width of 0.2-3.0 μm.

Preferably, the organic polymer comprises a polyether polyol or a polyisocyanate.

Preferably, the mass ratio of the nano carbon material to the organic polymer is (80-98): 2-20).

Preferably, the temperature of the reaction is 40-90 ℃.

Preferably, the grafting ratio of the modified nanocarbon material is 0.1 to 100 wt%.

Wherein the graphene may have a sheet diameter of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, a width of 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, or 3.0 μm, the nanocarbon material may be present in a mass ratio to the organic polymer in an amount of 80, 82, 84, 86, 88, 90, 92, 94, 96, or 98, the organic polymer may be present in an amount of 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20, and the temperature may be 40 ℃, 45 ℃, 50 ℃, 65 ℃, 90 ℃, 85 ℃, 75 ℃, 5, or 5 wt%, or 1% of the organic polymer may be present in an amount of the graft ratio to the mass ratio of the organic polymer 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 100 wt%, etc., but not limited to the above-listed values, and other values not listed within the above-mentioned range of values are also applicable.

The combination of the specific numerical values can ensure that the porosity of the heating element with the net-shaped hole wall reaches over 86.2 percent, so that the heating element has the characteristics of slow heat dissipation and good heat preservation capability, and meanwhile, the heating element has high compressive strength and can bear the processing and maintain the structure to be not damaged in practical production and use.

Preferably, the silicate solid waste includes any one or a combination of at least two of coal gangue, fly ash, red mud or slag, such as a combination of coal gangue and fly ash, a combination of fly ash and red mud, or a combination of red mud and slag, and the like, but is not limited to the above-listed combinations, and other combinations not listed in the above-mentioned combination range are also applicable.

The reticular hole wall heating element prepared by adopting the specific silicate solid waste not only greatly saves the cost, but also reduces the pollution of the silicate solid waste to the environment.

Preferably, the particle size of the silicate solid waste is not more than 45 μm.

Preferably, the polyether polyol has a molecular weight of 300-5000 g/mol.

Preferably, the polyether polyol has a viscosity of 100-500 mPas.

Preferably, the polyisocyanate includes any one of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate or toluene diisocyanate or a combination of at least two of them, such as polymethylene polyphenyl isocyanate and diphenylmethane diisocyanate, diphenylmethane diisocyanate and toluene diisocyanate, or polymethylene polyphenyl isocyanate and toluene diisocyanate, and the like, but is not limited to the above-listed combinations, and other combinations not listed in the above-mentioned combination range are also applicable.

Preferably, the silicone oil foam stabilizer comprises any one or a combination of at least two of dimethicone, silicone amide or dodecyl dimethyl amine oxide, such as a combination of dimethicone and silicone amide, a combination of silicone amide and dodecyl dimethyl amine oxide, or a combination of dimethicone and dodecyl dimethyl amine oxide, but not limited to the above-listed combinations, and other combinations not listed in the above-mentioned combination range are also applicable.

Preferably, the viscosity of the hydrolysis-resistant silicone oil is 100-300 mPas.

Wherein the particle size of the silicate solid waste may be 45 μm, 42 μm, 39 μm, 36 μm, 33 μm or 30 μm, the molecular weight of the polyether polyol may be 300g/mol, 500g/mol, 1000g/mol, 1500g/mol, 2000g/mol, 2500g/mol, 3000g/mol, 3500g/mol, 4000g/mol, 4500g/mol or 5000g/mol, the viscosity of the polyether polyol may be 100 mPas, 150 mPas, 200 mPas, 250 mPas, 300 mPas, 350 mPas, 400 mPas, 450 mPas or 500 mPas, the viscosity of the hydrolysis-resistant silicone oil may be 100 mPas, 120 mPas, 140 mPas, 160 mPas, 180 mPas, 200 mPas, 220 mPas, 240 mPas, 260 mPas, 280 mPas or 300 mPas, but not limited to the above values, other values not listed within the above numerical range are equally applicable.

Preferably, the blowing agent comprises water.

Preferably, the catalyst comprises dibutyl tin dilaurate and/or stannous octoate.

In a second aspect, the present invention provides a method for manufacturing a reticulated pore wall heating element as described above, comprising the steps of:

(1) mixing and stirring the modified nano-carbon material, silicate solid waste, polyether polyol, polyisocyanate, a silicone oil foam stabilizer, a foaming agent and a catalyst to obtain a ceramic green body;

(2) and (2) carrying out glue removal on the ceramic green body obtained in the step (1), and then drying under the protective gas condition to obtain the reticular hole wall heating element.

The preparation method is simple to operate, and the heating element with the net-shaped hole wall can be quickly and conveniently prepared.

Preferably, the stirring rate in step (1) is 300-2000rpm, and the time is 2-10 min.

Preferably, the temperature of the gel discharging in the step (2) is 200-.

Preferably, the temperature of the drying in the step (2) is 800-1300 ℃, and the time is 2-6 h.

Wherein, the stirring speed can be 300rpm, 500rpm, 700rpm, 900rpm, 1100rpm, 1300rpm, 1500rpm, 1700rpm or 2000rpm, etc., the stirring time can be 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10min, etc., the glue discharging temperature can be 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃ or 800 ℃, etc., the glue discharging time can be 3h, 5h, 10h, 15h, 20h, 25h, 30h, 35h or 40h, etc., the baking temperature can be 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, or 1300 ℃, etc., the baking time can be 2h, 3h, 4h, 5h or 6h, etc., but not limited to, the above-listed numerical values, and other numerical values not listed in the above numerical range are also applicable.

Preferably, the protective gas of step (2) comprises nitrogen or argon.

As a preferable technical scheme of the invention, the preparation method comprises the following steps:

(1) mixing the modified nano-carbon material, silicate solid waste, polyether polyol, polyisocyanate, silicone oil foam stabilizer, foaming agent and catalyst, and stirring at 300-2000rpm for 2-10min to obtain a ceramic green body;

(2) and (2) performing gel discharging on the ceramic green body obtained in the step (1) at 800 ℃ of 200-plus of materials for 3-40h, and then drying at 1300 ℃ of 800-plus of materials for 2-6h under the condition of protective gas to obtain the reticular hole wall heating element.

In a third aspect, the invention also provides the application of the reticular pore wall heating element in the preparation of the electrothermal material.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a reticular hole wall heating element with specific components, which has high efficiency, slow heat dissipation and good heat preservation effect; the influence of the silicate solid waste on the environment can be reduced by adopting the silicate solid waste as a raw material, and the production cost is greatly reduced; the reticular pore wall heating element has a porous reticular structure by utilizing the polyether polyol and the polyisocyanate for foaming, and the modified nano carbon material can be uniformly distributed, so that the reticular pore wall heating element has slow heat dissipation and high efficiency, when the current is introduced to the reticular pore wall heating element to be 2mA, the electrothermal transformation temperature reaches above 60 ℃, the heat preservation effect is good, and meanwhile, the ratio of the specific polyether polyol and the polyisocyanate and the content of the modified nano carbon material can realize accurate and controllable reticular pore wall structure without subsequent treatment; the nano carbon material is modified by organic polymer, so that the surface of the obtained modified nano carbon material is bonded with high-reactivity groups such as hydroxyl groups or isocyanate groups, and the like, and can generate cross-linking polymerization reaction with polyurethane monomer obtained by foaming organic polymer, so as to realize the construction of a mesh hole wall; meanwhile, the porosity reaches over 86.2 percent, so that the heating element with the net-shaped hole walls has the characteristics of slow heat dissipation and good heat preservation capability, and meanwhile, the compressive strength reaches over 1.5MPa, and the heating element can bear the processing in practical production and use to maintain the structure and is not damaged.

Drawings

FIG. 1 is a microstructure photograph of a net hole wall heating element provided in example 1;

fig. 2 is a photomicrograph of the modified graphene structure in the reticulated pore wall heating element provided in example 1;

fig. 3 is an image of the electrothermal conversion efficiency test of the mesh hole wall heating element provided in example 1.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

In the following examples and comparative examples, graphene was obtained from pure technical materials, Inc. of Dongguan, model 800 NM;

the carbon nanotube is purchased from Beijing German island gold science and technology ltd, and the model is CNT 104;

the conductive nano carbon black is purchased from Tianjin Yishi chemical product science and technology development limited company, and the model is TYT-5A;

the coal gangue is purchased from Shanxi Haoyao constant mining limited company, and the model is CG 61;

the fly ash is purchased from a processing plant of Chuangwei mineral products in Lingshou county, Hebei, and has the model number of fmh 1100;

the red mud is purchased from aluminum industry, Inc. of Henan of China aluminum and has the model of RML # 4;

polyether polyol is available from Wanhua chemical group, Inc. and has the model number of R2305;

polyisocyanate was purchased from Wanhua chemical group, Inc. with model number PM 200;

example 1

The embodiment provides a reticular pore wall heating element, which comprises the following components in parts by weight:

modified graphene	8 portions of	Silicone oil foam stabilizer	3 portions of
				Coal gangue	60 portions of	Deionized water	0.5 portion
Polyether polyols	15 portions of	Dibutyl tin dilaurate	1 part of
				Polyisocyanates	15 portions of

The preparation method comprises the following steps:

1) mixing graphene and polyether polyol according to a mass ratio of 90:10, and reacting at 70 ℃ for 0.5h to obtain modified graphene with a grafting rate of 2.00 wt%;

2) mixing coal gangue, polyether polyol, polyisocyanate, a silicone oil foam stabilizer, the modified graphene obtained in the step 1), deionized water and dibutyl tin dilaurate to obtain a mixed slurry, and mechanically stirring for 5min at a stirring speed of 1000rpm to foam to obtain a ceramic green body;

3) placing the ceramic green body obtained in the step 2) in a glue removing furnace, removing glue for 20h at 600 ℃, and finally preserving heat for 2h at 1000 ℃ under the condition of introducing argon gas to obtain the reticular pore wall heating element, wherein the microstructure of the reticular pore wall heating element is shown in figure 1, and the structure of the modified graphene in the reticular pore wall heating element is shown in figure 2.

Example 2

modified carbon nanotube	15 portions of	Silicone oil foam stabilizer	5 portions of
				Fly ash	90 portions of	Deionized water	1 part of
Polyether polyols	25 portions of	Dibutyl tin dilaurate	2 portions of
				Polyisocyanates	25 portions of

The preparation method comprises the following steps:

1) mixing the carbon nano tube with polyether polyol according to a mass ratio of 95:5, and reacting for 1h at 70 ℃ to obtain a modified carbon nano tube with a grafting rate of 5.00 wt%;

2) mixing fly ash, polyether polyol, polyisocyanate, a silicone oil foam stabilizer, the modified carbon nanotube obtained in the step 1), deionized water and dibutyl tin dilaurate to obtain a mixed slurry, and mechanically stirring for 8min at a stirring speed of 1200rpm to foam to obtain a ceramic green body;

3) placing the ceramic green body obtained in the step 2) in a glue discharging furnace, discharging glue for 40h at 200 ℃, and finally, preserving heat for 2h at 1300 ℃ under the condition of introducing argon gas to obtain the mesh hole wall heating element.

Example 3

modified conductive nano carbon black	0.5 portion	Silicone oil foam stabilizer	0.5 portion
				Red mud	30 portions of	Deionized water	0.1 part
Polyether polyols	4 portions of	Stannous octoate	0.01 part
				Polyisocyanates	5 portions of

The preparation method comprises the following steps:

1) mixing conductive nano carbon black with polyisocyanate according to a mass ratio of 80:20, and reacting at 70 ℃ for 1.5h to obtain modified conductive nano carbon black with a grafting rate of 20.00 wt%;

2) mixing red mud, polyether polyol, polyisocyanate, a silicone oil foam stabilizer, the modified conductive nano carbon black obtained in the step 1), deionized water and stannous octoate to obtain mixed slurry, and mechanically stirring at a stirring speed of 600rpm for 10min for foaming to obtain a ceramic green body;

3) placing the ceramic green body obtained in the step 2) in a glue discharging furnace, discharging glue for 3 hours at the temperature of 800 ℃, and finally, keeping the temperature for 6 hours at the temperature of 800 ℃ under the condition of introducing argon to obtain the reticular hole wall heating element.

Example 4

modified graphene	10 portions of	Silicone oil foam stabilizer	4 portions of
				Coal gangue	80 portions of	Deionized water	0.7 portion of
Polyether polyols	20 portions of	Dibutyl tin dilaurate	1.5 parts of
				Polyisocyanates	20 portions of

The preparation process was identical to example 1.

Example 5

modified graphene	5 portions of	Silicone oil foam stabilizer	1.5 parts of
				Coal gangue	40 portions of	Deionized water	0.3 part of
Polyether polyols	10 portions of	Dibutyl tin dilaurate	0.5 portion
				Polyisocyanates	10 portions of

The preparation process was identical to example 1.

Comparative example 1

The comparative example provides a reticular pore wall heating element which comprises the following components in parts by weight:

the preparation method is identical to example 1.

Comparative example 2

modified graphene	8 portions of	Silicone oil foam stabilizer	3 portions of
				Coal gangue	60 portions of	Deionized water	0.5 part of
Polyether polyols	30 portions of	Dibutyl tin dilaurate	1 part of
				Polyisocyanates	30 portions of

The preparation method is identical to example 1.

Comparative example 3

The comparative example provides a reticular hole wall heating element, which comprises the following components in parts by weight:

graphene	8 portions of	Silicone oil foam stabilizer	3 portions of
				Coal gangue	60 portions of	Deionized water	0.5 portion
Polyether polyols	15 portions of	Dibutyl tin dilaurate	1 part of
				Polyisocyanates	15 portions of

The preparation method comprises the following steps:

1) mixing coal gangue, polyether polyol, polyisocyanate, a silicone oil foam stabilizer, graphene, deionized water and dibutyltin dilaurate to obtain mixed slurry, and mechanically stirring for 5min at a stirring speed of 1000rpm to foam to obtain a ceramic green body;

2) placing the ceramic green body obtained in the step 1) in a glue discharging furnace, discharging glue for 20 hours at the temperature of 600 ℃, and finally, keeping the temperature for 2 hours at the temperature of 1000 ℃ under the condition of introducing argon to obtain the reticular hole wall heating element.

Comparative example 4

The comparative example provides a heating element, which comprises the following components in parts by weight:

modified graphene	8 portions of
		Coal gangue	60 portions of

The preparation method comprises the following steps:

1) mixing graphene and polyether polyol according to a mass ratio of 90:10, and reacting for 2 hours at 70 ℃ to obtain modified graphene with a grafting rate of 2.00 wt%;

2) mixing coal gangue with the modified graphene obtained in the step 1) to obtain mixed slurry, and mechanically stirring for 5min at a stirring speed of 1000rpm to obtain a ceramic green body;

3) and (3) preserving the temperature of the ceramic green body obtained in the step 2) for 2 hours at 1000 ℃ under the condition of introducing argon gas, thus obtaining the heating element.

Comparative example 5

A commercially available heating element.

And (3) performance testing:

the heating elements provided in examples 1 to 5 and comparative examples 1 to 5 were subjected to the tests of volume density, porosity and compressive strength (the volume density and porosity were measured in GB/T1966-1996, the test equipment was a Shanghai constant-level electron density balance FA2104J, the compressive strength was measured in GB/T1964-1996, and the test equipment was a Japanese Shimadzu AG-2000G mechanical testing machine), and the results were as follows:

the data show that the product provided by the invention has excellent pressure resistance effect, can withstand processing in actual production and use, and has high porosity, slow heat dissipation and good heat preservation effect.

The heating elements provided in examples 1 to 5 and comparative examples 1 to 5 were then subjected to an electrothermal transition efficiency test, and tested for an electrothermal transition temperature at an applied current of 2mA (standard for electrothermal transition temperature test: GB/T23107-2008, test equipment: LongWei, direct current power supply (TPR 3005-2D; test specimen size: 40 mm. times.40 mm. times.20 mm)). The test results are as follows, wherein fig. 3 is a test image of the reticulated pore wall heating element provided in example 1:

group of	Electrothermal transition temperature (. degree.C.)	Group of	Electrothermal transition temperature (. degree. C.)
				Example 1	75	Comparative example 1	58
Practice ofExample 2	71	Comparative example 2	56
				Example 3	68	Comparative example 3	52
Example 4	65	Comparative example 4	48
				Example 5	60	Comparative example 5	43

The data show that the product provided by the invention has higher efficiency, and the efficiency is improved by uniformly distributing the modified nano carbon material by utilizing the reticular pore walls; compared with the prior art, the electrothermal transformation temperature when the current is introduced to be 2mA is obviously improved beyond the protection range of the invention and reaches more than 60 ℃.

The applicant states that the invention is illustrated by the above embodiments of the invention, but the invention is not limited to the above embodiments, i.e. it does not mean that the invention must be implemented by the above embodiments. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of the raw materials of the product of the present invention, and the addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present invention does not separately describe various possible combinations.

Claims

1. The reticular pore wall heating element is characterized by comprising 0.5-15 parts by weight of modified nano carbon material, 30-90 parts by weight of silicate solid waste, 4-25 parts by weight of polyether polyol, 5-25 parts by weight of polyisocyanate, 0.5-5 parts by weight of silicone oil foam stabilizer, 0.1-1 part by weight of foaming agent and 0.01-2 parts by weight of catalyst.

2. The reticulated pore wall heating element according to claim 1, wherein the reticulated pore wall heating element comprises, by weight, 5 to 10 parts of the modified nanocarbon material, 40 to 80 parts of silicate solid waste, 10 to 20 parts of polyether polyol, 10 to 20 parts of polyisocyanate, 1.5 to 4 parts of silicone oil foam stabilizer, 0.3 to 0.7 part of foaming agent and 0.5 to 1.5 parts of catalyst.

3. The net hole wall heating element according to claim 1 or 2, wherein the modified nanocarbon material is prepared by a preparation method comprising the steps of: mixing a nano carbon material with an organic polymer solution, carrying out graft modification reaction, and then carrying out suction filtration, drying and scattering to obtain a modified nano carbon material;

preferably, the nano carbon material comprises any one of graphene, carbon nanotubes or conductive nano carbon black;

preferably, the sheet diameter of the graphene is 1-10 μm, and the width of the graphene is 0.2-3.0 μm;

preferably, the organic polymer comprises a polyether polyol or a polyisocyanate;

preferably, the mass ratio of the nano carbon material to the organic polymer is (80-98) to (2-20);

preferably, the temperature of the reaction is 40-90 ℃;

4. The reticulated pore wall heating element according to any one of claims 1 to 3, wherein the silicate solid waste comprises any one or a combination of at least two of coal gangue, fly ash, red mud or slag;

5. The reticulated pore wall heating element according to any one of claims 1 to 4, wherein the molecular weight of the polyether polyol is 300-5000 g/mol;

preferably, the polyether polyol has a viscosity of 100-500 mPas;

preferably, the polyisocyanate comprises any one of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate or toluene diisocyanate or a combination of at least two thereof.

6. The reticulated pore wall heating element of any one of claims 1 to 5, wherein the silicone oil foam stabilizer comprises any one of or a combination of at least two of dimethicone, silicone amide, or dodecyl dimethyl amine oxide;

preferably, the viscosity of the hydrolysis-resistant silicone oil is 100-300 mPas;

preferably, the blowing agent comprises water;

7. A method for manufacturing a net hole wall heating element according to any one of claims 1 to 6, comprising the steps of:

(1) mixing and stirring the modified nano carbon material, silicate solid waste, polyether polyol, polyisocyanate, silicone oil foam stabilizer, foaming agent and catalyst to obtain a ceramic green body;

(2) and (2) carrying out glue discharging on the ceramic green body obtained in the step (1), and then drying under the protective gas condition to obtain the mesh hole wall heating element.

8. The method as claimed in claim 7, wherein the stirring speed in step (1) is 300-2000rpm for 2-10 min;

preferably, the temperature of the gel discharging in the step (2) is 200-;

preferably, the temperature of the drying in the step (2) is 800-1300 ℃, and the time is 2-6 h;

preferably, the protective gas of step (2) comprises nitrogen or argon.

9. The method for producing a net hole wall heating element according to claim 7 or 8, characterized by comprising the steps of:

(2) and (2) gelatinizing the ceramic green body obtained in the step (1) at the temperature of 200-800 ℃ for 3-40h, and then drying at the temperature of 800-1300 ℃ for 2-6h under the protective gas condition to obtain the reticular hole wall heating element.

10. Use of a reticulated pore wall heating element according to any one of claims 1 to 6 in the preparation of an electrothermal material.