阅读说明：本技术 一种电子烟用陶瓷雾化芯及其制备方法和应用 (Ceramic atomizing core for electronic cigarette and preparation method and application thereof ) 是由 刘裔云 于 2021-09-06 设计创作，主要内容包括：本发明涉及电子烟技术领域,公开了一种电子烟用陶瓷雾化芯及其制备方法和应用。本发明雾化芯延外周至中心方向依次分为外、中、内三个芯层,每个芯层由氮化硅和氧化硅烧结而成,外、中、内三个芯层中的氮化硅长径比渐短,均为柱状或棒状的粉状氮化硅。本发明通过在原料配比中引入炭黑和不同长径比的柱状或棒状氮化硅,采用离心和外加磁场的成型方法制备坯体,结合两步烧结法(脱胶和烧结)使得炭黑和氮化硅的氧杂质在合适的温度和气氛条件下充分反应,以降低氮化硅中的晶格氧含量,从而制备出高热导的氮化硅外密内疏排列、孔隙有序排布的多孔陶瓷材料。(The invention relates to the technical field of electronic cigarettes, and discloses a ceramic atomizing core for an electronic cigarette and a preparation method and application thereof. The atomizing core is sequentially divided into an outer core layer, a middle core layer and an inner core layer along the direction from the periphery to the center, each core layer is formed by sintering silicon nitride and silicon oxide, the length-diameter ratio of the silicon nitride in the outer core layer, the middle core layer and the inner core layer is gradually shortened, and the silicon nitride is columnar or rod-shaped powdery silicon nitride. According to the invention, carbon black and columnar or rod-shaped silicon nitride with different length-diameter ratios are introduced into the raw material ratio, a blank is prepared by adopting a centrifugal and external magnetic field forming method, and a two-step sintering method (degumming and sintering) is combined to enable oxygen impurities of the carbon black and the silicon nitride to fully react under appropriate temperature and atmosphere conditions so as to reduce the lattice oxygen content in the silicon nitride, so that the porous ceramic material with high thermal conductivity, in which the silicon nitride is arranged densely at the outside and sparsely at the inside and pores are arranged orderly, is prepared.)

1. The ceramic atomizing core for the electronic cigarette is characterized in that the atomizing core is sequentially divided into an outer core layer, a middle core layer and an inner core layer along the direction from the periphery to the center, each core layer is formed by sintering silicon nitride and silicon oxide, and the silicon nitride in the outer core layer, the middle core layer and the inner core layer is gradually shortened in length-diameter ratio and is columnar or rod-shaped powdery silicon nitride.

2. The atomizing core for the electronic cigarette according to claim 1, wherein the thickness ratio of the outer, middle and inner core layers is (1-2): (3-4): (5-6).

3. The atomizing core for the electronic cigarette as in claim 1, wherein the silicon nitride length-diameter ratio in the outer core layer is 15-20, the silicon nitride length-diameter ratio in the middle core layer is 10-15, and the silicon nitride length-diameter ratio in the inner core layer is 7-10.

4. A method of making an atomizing core of claim 1, comprising:

step 1, preparing injection molding slurry by using a monomer, a cross-linking agent, a dispersing agent and a solvent;

step 2, adding a mixture of a sintering aid, silicon oxide and silicon nitride with different length-diameter ratios into the injection molding slurry to form the injection molding slurry of the outer, middle and inner core layers;

step 3, adjusting the pH value of the outer, middle and inner core layer injection molding slurry to 9-12, adding an initiator, and performing ball milling;

step 4, injecting the ball-milled outer core layer injection molding slurry into a mold, applying a magnetic field and carrying out centrifugal treatment, wherein rod-shaped or columnar silicon nitride is vertically arranged under the action of the magnetic field, and an outer core layer containing silicon nitride is formed on the outermost periphery departing from the center of the mold under the action of the centrifugal force, so that the outer core layer slurry is reacted for a period of time and is subjected to gel curing;

step 5, sequentially completing injection molding of the middle core layer and the inner core layer according to the mode of the step 4, and obtaining a biscuit after demolding and drying;

and 6, embedding carbon black powder into the biscuit after the biscuit is subjected to rubber discharge and sintering to obtain the atomization core.

5. The method according to claim 4, wherein the monomer is acrylamide.

6. The method according to claim 4, wherein the crosslinking agent is N, N' -methylenebisacrylamide.

7. The method of claim 4, wherein the dispersant is ammonium polyacrylate.

8. The method according to claim 4, wherein the sintering aid is a combination of silica, magnesia and calcium carbonate.

9. The ceramic atomizing core for the electronic cigarette prepared by the preparation method of any one of claims 4 to 8.

10. Use of the ceramic atomizing core for the electronic cigarette according to any one of claims 1 to 3 and 9 in the preparation of the electronic cigarette.

Technical Field

The application relates to the technical field of electronic cigarettes, in particular to a ceramic atomizing core for electronic cigarettes and a preparation method and application thereof.

Background

The electronic smoking set is an electronic device which transfers nicotine to a respiratory system by electrically heating and atomizing electronic atomized liquid. The atomizing core in the electronic smoking set absorbs the electronic atomized liquid, and the heating wire heats the atomizing core, so that the absorbed electronic atomized liquid is atomized to form aerosol which is sucked by a user.

At present, the existing electronic cigarette atomization core products in the market have the technical problem of nonuniform heating (even toxic gas formaldehyde is generated due to overhigh local temperature of an atomization surface), the technical defects bring poor sensory experience such as poor smoke mouthfeel for tobacco product consumers, and the poor industrial development and market popularization of related products of electronic cigarettes are not facilitated. Therefore, the high-thermal-conductivity porous ceramic atomizing core is provided for solving the problem, and the atomizing core has great significance for improving the comprehensive performance of the electronic cigarette product.

Disclosure of Invention

In view of the above, the invention aims to provide a ceramic atomizing core for an electronic cigarette and a preparation method thereof, so that the prepared atomizing core has higher thermal conductivity and porosity;

the invention also aims to provide the ceramic atomizing core for the electronic cigarette and the preparation method thereof, so that the prepared atomizing core has higher strength;

the invention also aims to provide the ceramic atomizing core for the electronic cigarette and the preparation method thereof, so that the prepared atomizing core has higher oil absorption rate;

another object of the present invention is to provide the use of the atomizing core prepared as above in the preparation of electronic cigarettes.

In order to solve the technical problems or at least partially solve the technical problems, the invention provides a ceramic atomizing core for an electronic cigarette, which is sequentially divided into an outer core layer, a middle core layer and an inner core layer along the direction from the periphery to the center, wherein each core layer is formed by sintering silicon nitride and silicon oxide, the length-diameter ratios of the silicon nitride in the outer core layer, the middle core layer and the inner core layer are gradually shortened, and the silicon nitride is columnar or rod-shaped powdery silicon nitride.

The shape of the atomizing core is suitable for the electronic cigarette and is generally cylindrical. Preferably, the thickness ratio of the outer core layer, the middle core layer and the inner core layer is (1-2): (3-4): (5-6).

Preferably, the silicon nitride aspect ratio in the outer core layer is 15-20, the silicon nitride aspect ratio in the middle core layer is 10-15, and the silicon nitride aspect ratio in the inner core layer is 7-10.

Compared with the high-temperature sintered product of conventional silicon dioxide, glass powder and pore-forming agent, the porous ceramic material prepared by the invention has high porosity and high thermal conductivity, and can overcome the technical problem that the atomization surface is heated unevenly when the porous ceramic material is used as the atomization core of the electronic cigarette. In addition, the atomization core also has higher compressive strength, is convenient to assemble and has higher oil absorption rate.

Meanwhile, the invention also provides a preparation method of the atomization core, which comprises the following steps:

step 1, preparing injection molding slurry by using a monomer, a cross-linking agent, a dispersing agent and a solvent;

step 2, adding a mixture of a sintering aid, silicon oxide and silicon nitride with different length-diameter ratios into the injection molding slurry to form the injection molding slurry of the outer, middle and inner core layers;

step 3, adjusting the pH value of the outer, middle and inner core layer injection molding slurry to 9-12, adding an initiator, and performing ball milling;

step 4, injecting the ball-milled outer core layer injection molding slurry into a mold, applying a magnetic field and carrying out centrifugal treatment, wherein rod-shaped or columnar silicon nitride is vertically arranged under the action of the magnetic field, and an outer core layer containing silicon nitride is formed on the outermost periphery departing from the center of the mold under the action of the centrifugal force, so that the outer core layer slurry is reacted for a period of time and is subjected to gel curing;

step 5, sequentially completing injection molding of the middle core layer and the inner core layer according to the mode of the step 4, and obtaining a biscuit after demolding and drying;

and 6, embedding carbon black powder into the biscuit after the biscuit is subjected to rubber discharge and sintering to obtain the atomization core.

In the preparation process, the injection molding slurry of the monomer, the cross-linking agent and the solvent (usually water) can assist the silicon nitride and the silicon oxide which are added later to be solidified on a mold, thereby being convenient for forming an outer core layer, an intermediate core layer and an inner core layer, and the dispersing agent is used for uniformly dispersing materials. Preferably, the monomer is acrylamide, the cross-linking agent is N, N' -methylene bisacrylamide, and the dispersing agent is ammonium polyacrylate. Wherein the monomer, the cross-linking agent, the dispersing agent and the solvent (deionized water) are in a proportion of (20-27) in parts by weight: (4-7): (1-1.8): 100.

preferably, the sintering aid is a combination of silica, magnesia and calcium carbonate. In the specific embodiment of the invention, the mass ratio of the three components is 1:3: 7.

Preferably, the initiator is used to initiate the cross-linking polymerization of the monomer and the cross-linking agent, and may be selected to be ammonium sulfate.

Preferably, the pH value can be adjusted by selecting a substance such as ammonia or urea.

Preferably, the weight parts of the silicon nitride, the silicon oxide and the sintering aid are (10-20): (30-50): (5-10).

In the specific embodiment of the invention, the step 4 of discharging the glue specifically comprises the following steps:

the temperature is kept at 600 ℃ for 3h from the room temperature to 200 ℃, the heating rate is 0.5 ℃/min, the heating rate is 0.25 ℃/min from 200 ℃ to 600 ℃.

During sintering, the biscuit is embedded into the carbon black powder, so that oxygen impurities of carbon black and silicon nitride can fully react under the sintering condition to reduce the lattice oxygen content in the silicon nitride, thereby improving the thermal conductivity of the silicon nitride and effectively avoiding the phenomenon of nonuniform heating. In a specific embodiment of the present invention, the sintering is specifically:

(1) vacuum-pumping atmosphere replacement: starting a vacuum pump, pumping out the air in the furnace to the pressure of-0.05 Mp, flushing pure argon to the pressure of 0.05Mpa, and repeating the step for 3 times to ensure that the air in the furnace is completely pumped out.

(2) Keeping the argon atmosphere at 620 ℃ and 650 ℃, and the heating rate is 8 ℃/min

(3) When the temperature rises to 620-650 ℃, the charging atmosphere is changed into hydrogen, the temperature is raised to 1650-1780 ℃, the temperature is kept for 240min, and the micro positive pressure is kept in the hearth when the temperature rises to 1650-1780 ℃, so that the combustion stability of the hearth is ensured, and the gas circulation is smooth.

(4) And after the heat preservation is finished, when the temperature is reduced to 1008 ℃, changing the flushing atmosphere into argon, and keeping the micro-positive pressure of the hearth.

(5) When the temperature is reduced to 485 ℃, the flushing atmosphere is changed into hydrogen, the micro positive pressure of the hearth is protected, and the atmosphere can be closed until the furnace temperature is reduced to below 50 ℃, and the furnace door can be opened to take out the sample.

The compression strength of the porous ceramic atomizing core prepared by the invention is 40-45MPa, the oil absorption rate is 3.1-3.5mg/s, the porosity is 60-70%, and the thermal conductivity is 2.8-3.2W/(m.k); the conventional method uses silica, glass powder 10-20, pore-forming agent (polystyrene microsphere), solvent (paraffin) and modifier (stearic acid) as raw materials to sinter the atomized core, the compressive strength is 10MPa, the oil absorption rate is 0.8mg/s, the porosity is 50%, and the thermal conductivity is 0.4W/(m.k); the comparison results of various indexes show that the porous ceramic atomizing core prepared by the preparation process has obvious advantages.

Therefore, the invention provides the ceramic atomizing core for the electronic cigarette prepared by the preparation method and the application of the ceramic atomizing core for the electronic cigarette in the preparation of the electronic cigarette.

According to the technical scheme, the carbon black and the columnar or rodlike silicon nitride with different length-diameter ratios are introduced into the raw material ratio, the blank is prepared by adopting a centrifugal method and an external magnetic field forming method, and the oxygen impurities of the carbon black and the silicon nitride are fully reacted under the appropriate temperature and atmosphere conditions by adopting a two-step sintering method (degumming and sintering) so as to reduce the lattice oxygen content in the silicon nitride, so that the porous ceramic material with high thermal conductivity, in which the silicon nitride is arranged densely at the outside and sparsely at the inside and pores are arranged orderly, is prepared. The porous ceramic material prepared by the invention has high porosity and high thermal conductivity, and can overcome the technical problem that an atomization surface is heated unevenly when being used as an atomization core of the electronic cigarette. In addition, the atomization core also has higher compressive strength, is convenient to assemble and has higher oil absorption rate.

Detailed Description

The invention discloses a ceramic atomizing core for electronic cigarettes and a preparation method and application thereof, and a person skilled in the art can realize the atomization by properly improving process parameters by referring to the content. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the processes, applications and products of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the processes, applications and products described herein may be made and used without departing from the spirit and scope of the invention. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that, in this document, relational terms such as "first" and "second", "step 1" and "step 2", and "(1)" and "(2)" are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In the comparison experiment of the invention, except the due differences of each group, the experiment environment, the process parameters, the raw material source batches and the like which are not particularly described are kept consistent, and the comparability of the experiment result is ensured.

The preparation process of the atomization core comprises the following raw materials in parts by weight:

monomer (b): a crosslinking agent: dispersing agent: solvent: silicon nitride powder: silicon oxide powder: sintering aid: initiator ═ (20-27): (4-7): (1-1.8): 100: (10-20): (30-50): (5-10);

the preparation process comprises the following steps:

1. monomer acrylamide, cross-linking agent N, N' -methylene bisacrylamide, dispersant ammonium polyacrylate and solvent deionized water) according to the parts by weight (20-27): (4-7): (1-1.8) mixing the raw materials to prepare a premixed solution, wherein the raw materials are 100;

2. adding (10-20) parts by weight of silicon nitride powder, (30-50) parts by weight of silicon oxide powder and (5-10) parts by weight of sintering aid (a composition of silicon oxide, magnesium oxide and calcium carbonate, 1:3:7) into the premixed liquid;

3. adding (10-20) parts by weight of initiator ammonium sulfate, adjusting the pH to 9-12 by using an aqueous solution containing 25-28% of ammonia, and performing ball milling for 3-5 h;

4. the length-diameter ratio of the silicon nitride powder is 7-20, a magnetic field and centrifugal force are applied, the silicon nitride powder with the length-diameter ratio of 15-20 is distributed on the outermost periphery departing from the center of the die to form a first silicon nitride layer (outer core layer), a second silicon nitride layer (middle core layer) with the length-diameter ratio of 10-15 and mutually abutted with the first silicon nitride layer is respectively formed in the direction from the periphery to the center, a third silicon nitride layer (inner core layer) with the length-diameter ratio of 7-10 and mutually abutted with the second silicon nitride layer is formed, and the thickness ratio of the first silicon nitride layer to the second silicon nitride layer to the third silicon nitride layer is (1-2): (3-4): (5-6), the thickness ratio of the silicon nitride layers is controlled through the number of cycles, and the silicon nitride with the large length-diameter ratio of the first silicon nitride layer is orderly arranged to form a compact silicon nitride outer film layer, so that oil locking is facilitated and the thermal conductivity is improved; the second silicon nitride layer and the third silicon nitride layer reach the center of the die, the silicon nitride is gradually short in length-diameter ratio and high in disorder degree, and the porosity of the subsequent ceramic body is higher, so that the tobacco tar infiltration is facilitated;

5. degumming biscuit: the temperature is kept at 600 ℃ for 3h from the room temperature to 200 ℃, the heating rate is 0.5 ℃/min, the heating rate is 0.25 ℃/min from 200 ℃ to 600 ℃;

6. and (3) sintering: after the rubber removal of the green blank is finished, embedding carbon black powder into a vacuum atmosphere sintering furnace for sintering;

(1) vacuum-pumping atmosphere replacement: starting a vacuum pump, pumping out the air in the furnace to the pressure of-0.05 Mp, flushing pure argon to the pressure of 0.05Mpa, and repeating the step for 3 times to ensure that the air in the furnace is completely pumped out.

(2) Keeping the argon atmosphere at 620 ℃ and 650 ℃, and the heating rate is 8 ℃/min

(3) When the temperature rises to 620-650 ℃, the charging atmosphere is changed into hydrogen, the temperature is raised to 1650-1780 ℃, the temperature is kept for 240min, and the micro positive pressure is kept in the hearth when the temperature rises to 1650-1780 ℃, so that the combustion stability of the hearth is ensured, and the gas circulation is smooth.

(4) And after the heat preservation is finished, when the temperature is reduced to 1008 ℃, changing the flushing atmosphere into argon, and keeping the micro-positive pressure of the hearth.

(5) When the temperature is reduced to 485 ℃, the flushing atmosphere is changed into hydrogen, the micro positive pressure of the hearth is protected, and the atmosphere can be closed until the furnace temperature is reduced to below 50 ℃, and the furnace door can be opened to take out the sample.

Example 1: the invention is compared with the conventional single ceramic powder

The process and technical effects of the invention and the comparative example are compared in the following table 1, in which each example parameter can be combined with or replaced by other example parameters;

TABLE 1

As can be seen from Table 1, the porous ceramic atomizing core prepared by the invention has the advantages that the compressive strength is 40-45MPa, the oil absorption rate is 3.1-3.5mg/s, the porosity is 60-70%, and the thermal conductivity is 2.8-3.2W/(m.k); the conventional method uses silica, glass powder 10-20, pore-forming agent (polystyrene microsphere), solvent (paraffin) and modifier (stearic acid) as raw materials to sinter the atomized core, the compressive strength is 10MPa, the oil absorption rate is 0.8mg/s, the porosity is 50%, and the thermal conductivity is 0.4W/(m.k); the comparison results of various indexes show that the porous ceramic atomizing core prepared by the preparation process has obvious advantages.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.