Dual curie temperature composite foil and preparation method therefor

Abstract

Disclosed in the present invention are a dual Curie temperature composite foil and a preparation method therefor. The dual Curie temperature composite foil of the present invention comprises a magnetic metal substrate, and a composite foil located on one side surface of the magnetic metal substrate and formed by carrying out cold rolling on ferrite magnetic particles and a forming agent. The composite foil having dual Curie temperatures is used for a heating material in decentralized electromagnetic heating low-temperature cigarette products, thereby facilitating precise control of heating. The present invention has the following advantages: (1) the composite foil has precise dual Curie temperatures, helping to improve the temperature control accuracy of decentralized electromagnetic products; (2) the composite foil has a relatively small total thickness, facilitating the continuous production process for forming into a cartridge; and (3) the metal substrate and the ferrite particles are bonded through a semi-metallurgical and semi-mechanical pattern, the production process is simple, and costs are low.

Description

A double Curie temperature composite foil and its preparation method

[0001] This application claims priority to Chinese Patent Application No. CN202411762582.7, filed on December 3, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This invention relates to the field of heating materials for heating cigarettes, and more specifically, to a double Curie temperature composite foil and its preparation method. Background Technology

[0003] Currently, in low-temperature cigarette products using electromagnetic heating technology, a decentralized structure is used where the electromagnetic heating element is placed inside the cigarette. This means that the heating element is embedded in the cartridge in the form of a needle, sheet, or rod. Because the device design is simpler and no cleaning is required after smoking, it is very popular among consumers.

[0004] However, in such structures, the heating element is separated from the appliance, and temperature measuring components cannot be directly placed inside the cigarette, making temperature measurement and control of decentralized electromagnetic heating products quite difficult. Common technologies typically employ a single-layer metal strip or multiple-layer metal sheet bonding method, using visible ohmic resistance or discrete compensation at different Curie temperatures to collect and detect current changes for temperature positioning and control. However, single-layer metal sheet temperature control relies on changes in visible resistance caused by Curie temperature, which suffers from low temperature control accuracy due to the mismatch in Curie temperatures between materials. Multi-layer metal compensation temperature control, on the other hand, uses the temperature of the material at a low Curie temperature point to pinpoint the current difference between the target temperature and the desired heating temperature—that is, the current value between the two peaks on the current curve—thus effectively improving temperature control accuracy. However, because the structure requires stable composite bonding of two materials under extremely thin conditions, the manufacturing process is complex, involving bimetallic liquid rolling, casting, etc., resulting in extremely high costs and difficulty in achieving the desired thickness. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a double Curie temperature composite foil, which can be used as a heating material for decentralized electromagnetic heating low-temperature cigarette products, offering low cost and high efficiency.

[0006] If necessary, the present invention also provides a method for preparing the above-mentioned double Curie temperature composite foil.

[0007] The technical solution provided by this invention is as follows:

[0008] A double Curie temperature composite foil includes a magnetic metal substrate and a composite foil whose one side surface is cold-rolled from ferrite magnetic particles and a forming agent.

[0009] The ferrite magnetic particles are selected from one or both of manganese-zinc ferrite or nickel-zinc ferrite.

[0010] The magnetic metal substrate is selected from foils made of iron, cobalt, and nickel.

[0011] The Curie temperature of the magnetic metal matrix is ​​not lower than 350°C.

[0012] The thickness of the raw material of the magnetic metal substrate foil is 0.1-0.3 mm.

[0013] The Curie temperature of the ferrite magnetic particles is not higher than 300°C.

[0014] The size of the ferrite magnetic particles is 10-100 μm.

[0015] The thickness of the double Curie temperature composite foil is 0.05-0.15 mm.

[0016] The molding agent is composed of 95wt%-97wt% ethanol and 3wt%-5wt% phenolic resin, and accounts for 40%-60% of the total weight of the ferrite magnetic particles and the molding agent.

[0017] The Curie temperature described in this invention can be measured using a magnetometer.

[0018] A method for preparing a double Curie temperature composite foil as described above, comprising:

[0019] (1) Cleaning: The magnetic metal substrate is acid-washed to remove the surface oxide film and contaminants;

[0020] (2) Ball milling: The ferrite magnetic particles are placed in a ball milling jar, and then high-purity ethanol is added for ball milling and mixing. The ball-to-material ratio is 5:1-10:1, the rotation speed is 150-300 rpm, and the ball milling time is not less than 2 hours.

[0021] (3) Drying: The prepared powder slurry is vacuum dried at a temperature of 70-90℃;

[0022] (4) Adhesive mixing; The dried mixed powder is mixed with the molding agent and homogenized. The molding agent is composed of 95wt%-97wt% ethanol and 3wt%-5wt% phenolic resin. The molding agent accounts for 40%-60% of the total weight of the mixed powder and the molding agent.

[0023] (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 100-120℃, an outlet temperature of 70-85℃, a pressure of 0.05-0.08MPa, a feed rate of 100-200ml / min, and an average particle size of 30-50μm after granulation.

[0024] (6) Coating; The granulated powder is uniformly coated on one side of the foil described in step (1) by cold spraying. The spraying gas pressure is 0.6-1.2 bar, the spraying temperature is 100-300℃, and the spraying distance is 10-15 mm.

[0025] (7) Rolling: The coated composite foil is rolled by a cold rolling mill with a rolling ratio of 50% and a rolling temperature of room temperature;

[0026] (8) Annealing; The rolled composite foil is placed in an annealing furnace for reduction annealing. The annealing atmosphere is H2, the pressure is 0.8-1.0 bar, the annealing temperature is 900-1200℃, and the holding time is 6-12h.

[0027] Compared to existing technologies, the present invention provides a double Curie temperature composite foil, comprising a magnetic metal substrate and a composite foil formed by cold rolling ferrite magnetic particles and a molding agent on one side surface. The composite foil with double Curie temperature is used as a heating material in decentralized electromagnetically heated low-temperature cigarette products, facilitating precise control of heating. The present invention has the following advantages:

[0028] (1) The composite foil has a precise double Curie temperature, which is beneficial to improving the temperature control accuracy of decentralized electromagnetic products;

[0029] (2) The total thickness of the composite foil is relatively small, which is beneficial to the continuous production process from molding to cartridge;

[0030] (3) The metal substrate and ferrite particles are semi-metallurgical and semi-mechanically bonded, and the production process is simple and the cost is low. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a process flow diagram of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0035] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0037] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0038] The sources of the substances used in the embodiments of this invention are as follows:

[0039] Iron foil: commercially available;

[0040] 1J50 iron-nickel alloy foil: commercially available;

[0041] FeCo alloy foil: Co≤50wt%, commercially available;

[0042] 430L stainless steel foil, commercially available;

[0043] Phenolic resin: from commercially available sources;

[0044] The remaining substances are from commercially available sources.

[0045] In this embodiment of the invention, the ball-to-material ratio refers to the mass ratio.

[0046] Example 1

[0047] Double Curie temperature composite foils were prepared using the following method:

[0048] (1) Cleaning: Pickling 0.1mm thick iron metal foil to remove surface oxide film and contaminants;

[0049] (2) Ball milling: 10μm manganese zinc ferrite particles were placed in a ball milling jar, and then high-purity ethanol was added before ball milling to obtain a powder slurry; the ball-to-particle ratio was 5:1, the rotation speed was 150rpm, and the ball milling time was 2h.

[0050] (3) Drying; The prepared powder slurry is vacuum dried at a temperature of 70℃;

[0051] (4) Adhesive mixing; The dried powder slurry is mixed with the molding agent and homogenized. The molding agent is composed of 97wt% ethanol and 3wt% phenolic resin, and the molding agent accounts for 40.00% of the total weight of the mixed powder and the molding agent.

[0052] (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 100-120℃, an outlet temperature of 70℃, a pressure of 0.05MPa, a feed rate of 100ml / min, and an average particle size of 30μm after granulation.

[0053] (6) Coating; As shown in Figure 1, the granulated particles 200 are uniformly cold-sprayed onto one side of the magnetic metal substrate (foil) 300 described in step (1) through the spray nozzle 100 of the spraying machine; the spraying gas pressure is 0.6 bar, the spraying temperature is 100℃, and the spraying distance is 10 mm.

[0054] (7) Rolling: The coated composite foil is rolled by a cold rolling mill 400 with a rolling ratio of 50% and a rolling temperature of room temperature;

[0055] (8) Annealing: The rolled composite foil is placed in an annealing furnace for reduction annealing treatment; the annealing atmosphere is H2, the pressure is 0.8 bar, the annealing temperature is 900℃, and the holding time is 6h.

[0056] Example 2

[0057] (1) Cleaning; pickling 0.3mm thick 430L stainless steel foil to remove surface oxide film and contaminants;

[0058] (2) Ball milling: 100μm nickel-zinc ferrite particles were placed in a ball milling jar, and then high-purity ethanol was added before ball milling to obtain a powder slurry. The ball-to-particle ratio was 10:1, the rotation speed was 300rpm, and the ball milling time was 12h.

[0059] (3) Drying; The prepared slurry is vacuum dried at a temperature of 90℃;

[0060] (4) Adhesive mixing; The dried mixed powder is mixed with the molding agent and homogenized. The molding agent is composed of 95wt% ethanol and 5wt% phenolic resin, and the molding agent accounts for 60.00% of the total weight of the mixed powder and the molding agent.

[0061] (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 120℃, an outlet temperature of 85℃, a pressure of 0.08MPa, a feed rate of 200ml / min, and an average particle size of 50μm after granulation.

[0062] (6) Coating; As shown in Figure 1, the granulated particles 200 are uniformly cold-sprayed onto one side of the magnetic metal substrate (foil) 300 described in step (1) through the spray nozzle 100 of the spraying machine; the spraying gas pressure is 1.2 bar, the spraying temperature is 300℃, and the spraying distance is 15 mm.

[0063] (7) Rolling: The coated composite foil is rolled by a cold rolling mill 400 with a rolling ratio of 50% and a rolling temperature of room temperature;

[0064] (8) Annealing; The rolled composite foil was placed in an annealing furnace for reduction annealing. The annealing atmosphere was H2, the pressure was 1.0 bar, the annealing temperature was 1200℃, and the holding time was 12h.

[0065] Example 3:

[0066] (1) Cleaning; pickling 0.15mm thick 1J50 iron-nickel alloy foil to remove surface oxide film and contaminants;

[0067] 2) Ball milling; 50μm nickel-zinc ferrite particles were placed in a ball milling jar, and then high-purity ethanol was added before ball milling to obtain a powder slurry. The ball-to-particle ratio was 7:1, the rotation speed was 200 rpm, and the ball milling time was 10 hours.

[0068] 3) Drying; The prepared powder slurry is vacuum dried at a temperature of 90℃;

[0069] 4) Adhesive mixing; The dried mixed powder is mixed with the molding agent and homogenized. The molding agent is composed of 96 wt% ethanol and 4 wt% phenolic resin, and the molding agent accounts for 55.00% of the total weight of the mixed powder and the molding agent.

[0070] (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 110℃, an outlet temperature of 80℃, a pressure of 0.07MPa, a feed rate of 150ml / min, and an average particle size of 40μm after granulation.

[0071] (6) Coating; As shown in Figure 1, the granulated particles 200 are uniformly cold-sprayed onto one side of the magnetic metal substrate (foil) 300 described in step (1) through the spray nozzle 100 of the spraying machine; the spraying gas pressure is 1.1 bar, the spraying temperature is 200℃, and the spraying distance is 12 mm.

[0072] (7) Rolling: The coated composite foil is rolled by a cold rolling mill 400 with a rolling ratio of 50% and a rolling temperature of room temperature;

[0073] (8) Annealing: The rolled composite foil is placed in an annealing furnace for reduction annealing treatment. The annealing atmosphere is H2, the pressure is 1.0 bar, the annealing temperature is 1000℃, and the holding time is 6h.

[0074] Example 4:

[0075] (1) Cleaning; pickling of 0.2mm thick FeCo alloy foil to remove surface oxide film and contaminants;

[0076] (2) Ball milling: 35μm nickel-zinc ferrite powder was placed in a ball milling jar, and then high-purity ethanol was added before ball milling to obtain a powder slurry. The ball-to-powder ratio was 7:1, the rotation speed was 220 rpm, and the ball milling time was 48h.

[0077] (3) Drying; The prepared powder slurry is vacuum dried at a temperature of 90℃;

[0078] (4) Adhesive mixing; The dried mixed powder is mixed with the molding agent and homogenized. The molding agent is composed of 96 wt% ethanol and 4 wt% phenolic resin, and the molding agent accounts for 50.00% of the total weight of the mixed powder and the molding agent.

[0079] (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 120℃, an outlet temperature of 80℃, a pressure of 0.06MPa, a feed rate of 180ml / min, and an average particle size of 40μm after granulation.

[0080] (6) Coating; As shown in Figure 1, the granulated particles 200 are uniformly cold-sprayed onto one side of the magnetic metal substrate (foil) 300 described in step (1) through the spray nozzle 100 of the spraying machine; The spraying gas pressure is 1.0 bar, the spraying temperature is 180°C, and the spraying distance is 10 mm.

[0081] (7) Rolling: The coated composite foil is rolled by a cold rolling mill 400 with a rolling ratio of 50% and a rolling temperature of room temperature;

[0082] (8) Annealing: The rolled composite foil is placed in an annealing furnace for reduction annealing treatment; the annealing atmosphere is H2, the pressure is 1.0 bar, the annealing temperature is 1050℃, and the holding time is 6h.

[0083] The foils prepared in Examples 1-4 were subjected to Curie temperature and thickness tests, and the results are listed in Table 1.

[0084] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not 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.

Claims

1. A double Curie temperature composite foil, characterized in that: It includes a magnetic metal substrate and a composite foil made by cold rolling one side of the substrate with ferrite magnetic particles and a forming agent.

2. The double Curie temperature composite foil as described in claim 1, characterized in that: The ferrite magnetic particles are selected from one or both of MnZn ferrite or NiZn ferrite.

3. The double Curie temperature composite foil as described in claim 1, characterized in that: The magnetic metal substrate is selected from foils made of iron, cobalt, and nickel.

4. The double Curie temperature composite foil as described in claim 1, characterized in that: The Curie temperature of the magnetic metal matrix is ​​not lower than 350°C.

5. The double Curie temperature composite foil as described in claim 1, characterized in that: The thickness of the raw material for the magnetic metal substrate foil is 0.1-0.3 mm.

6. The double Curie temperature composite foil as described in claim 1, characterized in that: The Curie temperature of the ferrite magnetic particles is not higher than 300°C.

7. The double Curie temperature composite foil as described in claim 1, characterized in that: The size of the ferrite magnetic particles is 10-100 μm.

8. The double Curie temperature composite foil as described in claim 1, characterized in that: The thickness of the double Curie temperature composite foil is 0.05-0.15 mm.

9. The double Curie temperature composite foil as described in claim 1, characterized in that: The molding agent is composed of 95wt%-97wt% ethanol and 3wt%-5wt% phenolic resin, and the molding agent accounts for 40%-60% of the total weight of the ferrite magnetic particles and the molding agent.

10. A method for preparing a double Curie temperature composite foil as described in any one of claims 1-9, characterized in that... include: (1) Cleaning: The magnetic metal substrate is acid-washed to remove the surface oxide film and contaminants; (2) Ball milling: The ferrite magnetic particles are placed in a ball milling jar, and then high-purity ethanol is added for ball milling and mixing. The ball-to-material ratio is 5:1-10:1, the rotation speed is 150-300 rpm, and the ball milling time is not less than 2 hours. (3) Drying: The prepared powder slurry is vacuum dried at a temperature of 70-90℃; (4) Adhesive mixing; The dried mixed powder is mixed with the molding agent and homogenized. The molding agent is composed of 95wt%-97wt% ethanol and 3wt%-5wt% phenolic resin. The molding agent accounts for 40%-60% of the total weight of the mixed powder and the molding agent. (5) Spray granulation; The slurry after adding adhesive is granulated in a spray granulator with an inlet temperature of 100-120℃, an outlet temperature of 70-85℃, a pressure of 0.05-0.08MPa, a feed rate of 100-200ml / min, and an average particle size of 30-50μm after granulation. (6) Coating; The granulated powder is uniformly coated on one side of the foil described in step (1) by cold spraying. The spraying gas pressure is 0.6-1.2 bar, the spraying temperature is 100-300℃, and the spraying distance is 10-15 mm. (7) Rolling: The coated composite foil is rolled by a cold rolling mill with a rolling ratio of 50% and a rolling temperature of room temperature; (8) Annealing: The rolled composite foil is placed in an annealing furnace for reduction annealing treatment. The annealing atmosphere is H2, the pressure is 0.8-1.0 bar, the annealing temperature is 900-1200℃, and the holding time is 6-12h.

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