Method for manufacturing multi-frequency radiation thermal field by using blackbody radiation to perform auxiliary heating on pole piece
The blackbody radiation method for electrode sheet drying addresses discontinuous drying gradients and shrinkage issues by using a single roll with adjustable components and radiation panels, improving efficiency and quality while reducing energy use and space.
Patent Information
- Application Number
- CN202510271439.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-08
- Publication Date
- 2025-07-15
AI Technical Summary
In the prior art, contact and non-contact drying methods have risks of drying gradient discontinuous, excessive shrinkage of the electrode sheet and plastic deformation in the electrode sheet production, which affects the production quality of the electrode sheet.
A multi-frequency radiant heat field is created by using blackbody radiation, and the electrode sheet is assisted by heating the heating assembly and the radiation receiving transmitter plate to form a three-dimensional composite heating mode. Combined with a single variable temperature heating roller, segmented temperature control heating is achieved, reducing the complexity of roller speed and temperature coordination, and absorbing and concentrating radiation energy through the radiation receiving transmitter plate to form a gradient heat field.
It improves the baking efficiency and heating uniformity of the pole sheet, reduces the risk of drying discontinuity and the scaling rate exceeding the standard, reduces plastic deformation, optimizes the equipment footprint and reduces energy consumption, and improves the production quality and consistency of the pole sheet.
Smart Images
Figure CN120306224A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of pole piece manufacturing, and particularly to a method for applying blackbody radiation to manufacture a multi-frequency radiation thermal field for auxiliary heating of pole pieces. Background Art
[0002] In the production process of lithium batteries, contact drying methods such as roller drying or non-contact drying methods such as radiation are usually used to dry and remove water from battery pole pieces.
[0003] In the actual production process, since the evaporation rate and surface tension of the solvent (such as water or NMP) in the coating slurry are different at different temperatures, it is necessary to perform segmented heating on the pole piece so that the solvent can evaporate slowly in the low-temperature stage (such as the initial stage) of the coating slurry, reducing the risk of coating cracking caused by excessive capillary pressure, and accelerating the complete removal of the solvent in the medium-high temperature stage (such as the subsequent stage) to ensure uniform curing of the pole piece. In the prior art, when using the contact drying method, multiple continuous heating rollers are usually used to perform contact heating on the pole piece, and the segmented heating of the pole piece is achieved by separately controlling the temperature of each heating roller. However, this method requires precise coordination of the roller speed and temperature of multiple rollers. If the production line speed fluctuates, it is easy to cause discontinuous drying gradients or excessive shrinkage rates of the pole pieces, affecting the production quality of the pole pieces. In addition, multi-roller drying is likely to result in an overly long path for the pole piece, and the pole piece is prone to plastic deformation under the action of continuous tension, affecting the production quality of the pole piece. When using non-contact drying methods such as radiation, traditional radiation heating is performed by multiple radiation tubes for segmented heating, and the formed radiation field gradient is discontinuous, resulting in discontinuous drying gradients of the pole piece and affecting the production quality of the pole piece, which urgently needs to be solved. Summary of the Invention
[0004] In view of the above deficiencies in the prior art, the present application provides a method for applying blackbody radiation to manufacture a multi-frequency radiation thermal field for auxiliary heating of pole pieces. By adding a radiation receiving and emitting plate and cooperating with several heating components capable of generating radiation, the principle of blackbody radiation is applied to assist in heating the pole piece undergoing roller drying, thereby solving the problems of discontinuous drying gradients or excessive shrinkage rates of the pole piece.
[0005] The above object of the present invention is achieved by the following technical solutions: A method for applying blackbody radiation to manufacture a multi-frequency radiation thermal field for auxiliary heating of pole pieces, comprising the following steps: Unroll the pole piece and perform a coating process on one surface of the pole piece; Wind the coated pole piece around a heating roller, and arrange several heating components for emitting radiation along the circumferential direction of the heating roller from the side where the heating roller contacts the pole piece. The several heating components are sequentially divided into several variable temperature groups according to groups to control the temperature of the heating components in each variable temperature group, and perform a baking process synchronously with the heating roller; A radiation receiving and emitting plate is arranged between the heating roller and several variable temperature groups. The radiation receiving and emitting plate is used to absorb the radiation emitted by each heating component and emit radiation to the electrode sheet on the surface of the heating roller.
[0006] By adopting the above technical solution, compared with the traditional multi-roller segmented drying method, this solution uses a single heating roller combined with heating components capable of variable temperature, which can reduce the complexity of the coordination between the roller speed and temperature, and the heating roller contacts the electrode sheet to heat the coating material from the inside out. Several heating components perform non-contact heating on the coating material from the outer layer to the inner layer through radiation via the radiation receiving and emitting plate, heating the outer layer and the inner layer of the coating material simultaneously to form a three-dimensional composite heating mode, thereby improving the baking efficiency and heating uniformity of the coating material. And through the precise sequential temperature control of several variable temperature groups, the function of segmented temperature control heating is realized. Then, after being absorbed by the radiation receiving and emitting plate, the radiation energy can be concentrated in the radiation receiving and emitting plate, and then the radiation energy is concentrated and emitted to the coating material of the electrode sheet to form a gradient radiation heat field. Since the coating material of the electrode sheet is a black substance, it has a strong ability to absorb the spectra in each spectral band and convert these spectral radiations into internal energy to complete the auxiliary heating of the electrode sheet, and the contact drying and conveying of a single heating roller can reduce the influence of multi-roller conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or the shrinkage rate of the electrode sheet exceeding the standard. At the same time, since a single heating roller is used for baking, the path of the electrode sheet is greatly shortened, the time for the electrode sheet to be subjected to continuous tension is reduced, the risk of plastic deformation is reduced, the production quality and consistency of the electrode sheet are improved, and the equipment floor space is greatly reduced, the energy consumption is reduced, and the requirements for energy conservation and emission reduction are met.
[0007] In a preferred example of the present application, it can be further configured that: the heating component includes a radiation tube, which is used to emit radiation light towards the absorption side of the radiation receiving and emitting plate.
[0008] In a preferred example of the present application, it can be further configured that: the heating component further includes a closed glass cover, and the radiation tube is arranged inside the closed glass cover.
[0009] By adopting the above technical solution, sealing the radiation tube in the closed glass cover can prevent the occurrence of discharge and sparking phenomena inside the equipment and avoid the explosion caused by combustible gases inside the equipment.
[0010] In a preferred example of the present application, it can be further configured that: the radiation light source in the radiation tube is at least one of infrared light or ultraviolet light.
[0011] In a preferred example of the present application, it can be further configured that: the radiation receiving and emitting plate is made of frosted glass.
[0012] By adopting the above technical solutions, the high transparency and diffuse reflection characteristics of the frosted glass enable it to better capture and absorb radiant energy, thereby improving the drying efficiency and drying quality. In addition, the rough structure on the surface of the frosted glass can evenly distribute the radiant energy on the plate surface, avoiding local overheating or uneven temperature phenomena. This evenly distributed radiant energy helps to improve the uniformity of the pole piece's heat absorption, thereby enhancing the drying effect.
[0013] In a preferred example of this application, it can be further configured that: the radiation receiving and emitting plate is made of a carbon-based wave-absorbing material, the absorption side of the radiation receiving and emitting plate is coated with a high-absorbance and low-emittance coating, and the emission side of the radiation receiving and emitting plate is coated with a high-emittance coating.
[0014] By adopting the above technical solutions, the carbon-based wave-absorbing material has high dielectric loss and magnetic loss characteristics, can achieve broadband absorption by converting electromagnetic wave energy into heat energy, and its porous or layered structure can enhance the multiple reflections and attenuation of electromagnetic waves inside the material, which is suitable for the wave-absorbing requirements in the high-frequency band. Then, after being absorbed by the high-absorbance coating on the surface of the radiation receiving and emitting plate, the radiant energy is uniformly emitted to the coating material of the pole piece for the second time, forming a gradient radiant heat field. Since the coating material of the pole piece is a black substance, it has a strong ability to absorb the spectra in each spectral band and converts these spectral radiations into internal energy to complete the auxiliary heating of the pole piece.
[0015] In a preferred example of this application, it can be further configured that: the high-absorbance and low-emittance coating is indium tin oxide, and the high-emittance coating is a black paint coating.
[0016] In a preferred example of this application, it can be further configured that: the radiation receiving and emitting plate is made of a carbon-based wave-absorbing material, and both the absorption side and the emission side of the radiation receiving and emitting plate are coated with a black paint coating.
[0017] In a preferred example of this application, it can be further configured that: the shape of the radiation receiving and emitting plate is adapted to the shape of the heating roller surface.
[0018] By adopting the above technical solutions, through the shape design of the radiation receiving and emitting plate, the uniformity of the distance from the radiation receiving and emitting plate to the heating roller surface is achieved, thereby optimizing the temperature distribution and ensuring the uniform heating of the pole piece.
[0019] In a preferred example of this application, it can be further configured that: the pole piece after baking and drying is subjected to a tempering treatment, and the tempering temperature is 70 - 220 degrees Celsius.
[0020] By adopting the above technical solutions, the tempering treatment makes the atomic structure inside the pole piece rearrange through heating and heat preservation, effectively relieving the internal stress generated due to temperature gradient and uneven shrinkage during the drying process, reducing the risk of pole piece deformation or cracking, and achieving stress release and uniform pole piece structure.
[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. Compared with the traditional multi-roll segmented drying method, this solution uses a single heating roller combined with a heating component capable of varying temperature, which can reduce the complexity of coordinating the roller speed and temperature. The heating roller contacts the electrode sheet, heating the coating material from the inside out. Several heating components perform non-contact heating on the coating material from the outer layer to the inner layer through radiation by receiving and emitting plates, heating the outer and inner layers of the coating material simultaneously, forming a three-dimensional composite heating mode, thereby improving the baking efficiency and heating uniformity of the coating material. Through precise sequential temperature control of several variable-temperature groups, the function of segmented temperature control heating is realized. Then, after being absorbed by the radiation receiving and emitting plates, the radiation energy can be concentrated in the radiation receiving and emitting plates, and then the radiation energy is concentrated and emitted onto the coating material of the electrode sheet to form a gradient radiation heat field. Since the coating material of the electrode sheet is a black substance, it has a strong ability to absorb spectra in various spectral bands and converts these spectral radiations into internal energy to complete the auxiliary heating of the electrode sheet. In addition, the contact drying and conveying of the single heating roller can reduce the influence of multi-roll conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or excessive shrinkage rate of the electrode sheet. At the same time, since a single heating roller is used for baking, the path of the electrode sheet is greatly shortened, reducing the time for the electrode sheet to be under continuous tension, reducing the risk of plastic deformation, improving the production quality and consistency of the electrode sheet, and significantly reducing the floor space of the equipment, reducing energy consumption and meeting the requirements of energy conservation and emission reduction.
[0022] 2. The radiation receiving and emitting plate made of carbon-based wave-absorbing material has high dielectric loss and magnetic loss characteristics, can achieve broadband absorption by converting electromagnetic wave energy into heat energy. Its porous or layered structure can enhance the multiple reflections and attenuation of electromagnetic waves inside the material, suitable for the wave-absorbing requirements in the high-frequency band. Then, after being absorbed by the high-absorption rate coating on the surface of the radiation receiving and emitting plate, the radiation energy is uniformly emitted onto the coating material of the electrode sheet for the second time to form a gradient radiation heat field. Since the coating material of the electrode sheet is a black substance, it has a strong ability to absorb spectra in various spectral bands and converts these spectral radiations into internal energy to complete the auxiliary heating of the electrode sheet.
[0023] 3. By sealing the radiation tube in a closed glass cover, the occurrence of discharge and sparking phenomena inside the equipment can be prevented, avoiding the explosion caused by flammable gases inside the equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 is a partial schematic diagram of the equipment structure when applying the method of manufacturing a multi-frequency radiation heat field for auxiliary heating of electrode sheets using blackbody radiation in the present application; Reference Numerals: 1, pole piece; 2, heating roller; 3, heating assembly; 31, radiation tube; 32, closed glass cover; 4, radiation receiving and emitting plate. Detailed Embodiment
[0025] The following describes exemplary embodiments of the present application with reference to the accompanying drawings. Various details of the embodiments of the present application are included to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.
[0026] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure.
[0027] In addition, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after, unless otherwise specified.
[0028] Next, refer to the attached Figure 1 Describe a method for auxiliary heating of a pole piece by applying blackbody radiation to manufacture a multi-frequency radiation thermal field.
[0029] A method for auxiliary heating of a pole piece by applying blackbody radiation to manufacture a multi-frequency radiation thermal field includes the following steps: Unroll the pole piece 1 and perform a coating process on one surface of the pole piece 1; Wind the coated pole piece 1 around the heating roller 2, and arrange a number of heating assemblies 3 for emitting radiation along the circumferential direction of the heating roller 2 from the side where the heating roller 2 contacts the pole piece 1. The number of heating assemblies 3 is divided into several variable temperature groups in sequence according to groups to control the temperature of the heating assemblies 3 under each variable temperature group, and perform a baking process synchronously with the heating roller 2; A radiation receiving and emitting plate 4 is arranged between the heating roller 2 and the several variable temperature groups. The radiation receiving and emitting plate 4 is used to absorb the radiation emitted by each heating assembly 3 and emit radiation to the pole piece 1 on the surface of the heating roller 2.
[0030] During the working process, auxiliary heating is carried out by dividing into multiple variable-temperature groups. In the low-temperature stage, the rapid volatilization of the solvent is slowed down, and the risk of coating cracking is reduced. In the medium- and high-temperature stages, the complete removal of the solvent is accelerated to ensure uniform curing of the electrode sheet 1, completing the segmented heating of the electrode sheet 1. Compared with the traditional multi-roller segmented drying method, this solution uses a single heating roller 2 combined with a heating component 3 capable of varying temperature, which can reduce the complexity of coordinating the roller speed and temperature. In addition, the heating roller 2 heats the coating material from the inside out by contacting the electrode sheet 1, and several heating components 3 perform non-contact heating on the coating material from the outer layer to the inner layer through radiation via the radiation receiving and emitting plate 4, heating the outer and inner layers of the coating material simultaneously to form a three-dimensional composite heating mode, thereby improving the baking efficiency and heating uniformity of the coating material. And through precise sequential temperature control of several variable-temperature groups, the function of segmented temperature control heating is realized. Then, after being absorbed by the radiation receiving and emitting plate 4, the radiation energy can be concentrated in the radiation receiving and emitting plate 4 and then concentratedly emitted to the coating material of the electrode sheet 1 to form a gradient radiation heat field. Since the coating material of the electrode sheet 1 is a black substance, it has a strong ability to absorb the spectra in each spectral band and convert these spectral radiations into internal energy to complete the auxiliary heating of the electrode sheet 1. And the contact drying and conveying of the single heating roller 2 can reduce the influence of multi-roller conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or the shrinkage rate of the electrode sheet 1 exceeding the standard. At the same time, since a single heating roller 2 is used for baking, the path of the electrode sheet 1 is greatly shortened, reducing the time for the electrode sheet 1 to be affected by continuous tension and the risk of plastic deformation, improving the production quality and consistency of the electrode sheet 1, and significantly reducing the equipment floor space, reducing energy consumption and meeting the requirements of energy conservation and emission reduction.
[0031] Preferably, the heating component 3 includes a radiation tube 31, which is used to emit radiation light toward the absorption side of the radiation receiving and emitting plate 4 to provide an absorption radiation source for the radiation receiving and emitting plate 4.
[0032] Furthermore, the heating component 3 further includes a closed glass cover 32. The radiation tube 31 is arranged inside the closed glass cover 32. By sealing the radiation tube 31 inside the closed glass cover 32, the occurrence of discharge and sparking phenomena inside the equipment can be prevented, avoiding explosion caused by flammable gases inside the equipment.
[0033] Specifically, the radiation light source in the radiation tube 31 is at least one of infrared light or ultraviolet light to meet the working conditions of blackbody radiation.
[0034] In one embodiment, the radiation receiving and emitting plate 4 is made of frosted glass. The high transparency and diffuse reflection characteristics of the frosted glass enable it to better capture and absorb radiation energy, thereby improving the drying efficiency and quality. In addition, the rough structure on the surface of the frosted glass can evenly distribute the radiation energy on the plate surface, avoiding the phenomenon of local overheating or uneven temperature. This evenly distributed radiation energy helps to improve the uniformity of heat reception of the electrode sheet 1, thus enhancing the drying effect.
[0035] In another embodiment, the radiation receiving and emitting plate 4 is made of a carbon-based wave-absorbing material. A coating with high absorption rate and low emissivity is coated on the absorption side of the radiation receiving and emitting plate 4, and a coating with high emissivity is coated on the emission side of the radiation receiving and emitting plate 4. The carbon-based wave-absorbing material has high dielectric loss and magnetic loss characteristics, such as carbon fiber, graphene, etc., and can achieve broadband absorption by converting electromagnetic wave energy into heat energy. Its porous or layered structure can enhance the multiple reflections and attenuation of electromagnetic waves inside the material, and is suitable for the wave-absorbing requirements in the high-frequency band. Then, after being absorbed by the high-absorption-rate coating on the surface of the radiation receiving and emitting plate 4, the radiation energy is evenly emitted to the coated material of the electrode sheet 1 for the second time, forming a gradient radiation heat field. Since the coated material of the electrode sheet 1 is a black substance, it has a strong ability to absorb the spectra in various spectral bands and convert these spectral radiations into internal energy to complete the auxiliary heating of the electrode sheet 1.
[0036] Preferably, the coating with high absorption rate and low emissivity is indium tin oxide, and the coating with high emissivity is a black paint coating. On the absorption side, indium tin oxide (ITO) has a high infrared transmittance (>80%) and a low emissivity (<0.2), allowing the energy in the infrared band to penetrate the surface layer. At the same time, through the design of the material impedance gradient (such as a multi-layer composite structure), the gradual absorption of electromagnetic waves from the surface to the inside can be realized, reducing reflection. At the same time, the low-emissivity coating made of indium tin oxide can inhibit the loss of the material's own thermal radiation energy. Combining with the wave-absorbing characteristics of the carbon base material of the radiation receiving and emitting plate 4, the absorbed energy is converted into heat energy and stored inside the material, which can avoid secondary radiation interference. On the emission side, the black paint has a high infrared emissivity (>0.9), and can efficiently release the heat energy absorbed by the material to the external environment in the form of infrared radiation, so that the coated material on the surface of the electrode sheet 1 can absorb it, which is suitable for the working conditions of blackbody radiation.
[0037] In one embodiment, the radiation receiving and emitting plate 4 is made of a carbon-based wave-absorbing material, and black paint coatings are coated on both the absorption side and the emission side of the radiation receiving and emitting plate 4. Specifically, when bidirectional high-efficiency radiation is required, coating black paint on both sides can improve the overall thermal emission efficiency. Compared with the previous embodiment, it may sacrifice the selective filtering function of the absorption side, because it is suitable for scenarios with low requirements for electromagnetic wave absorption.
[0038] Preferably, the shape of the radiation receiving and emitting plate 4 is adapted to the shape of the roller surface of the heating roller 2. Through the shape design of the radiation receiving and emitting plate 4, the uniformity of the distance from the radiation receiving and emitting plate 4 to the roller surface of the heating roller 2 is achieved, thereby optimizing the temperature distribution and ensuring uniform heating of the electrode sheet 1.
[0039] Further, after the baking process is completed, the baked and dried electrode sheet 1 is subjected to a tempering treatment. The tempering temperature is 70 - 220 degrees Celsius. Among them, the tempering treatment makes the atomic structure inside the electrode sheet 1 rearrange through heating and heat preservation, effectively relieving the internal stress generated due to temperature gradient and uneven shrinkage during the drying process, reducing the risk of deformation or cracking of the electrode sheet 1, and achieving stress release and uniform structure of the electrode sheet 1.
[0040] The above specific embodiments do not limit the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.
Claims
1. A method for auxiliary heating of a pole piece by using blackbody radiation to produce a multi-frequency radiation thermal field, characterized in that, It includes the following steps: Unwind the pole piece (1) and perform a coating process on one surface of the pole piece (1); Wind the coated pole piece (1) around the heating roller (2). Along the circumferential direction of the heating roller (2) on the side where the heating roller (2) contacts the pole piece (1), arrange a number of heating components (3) for emitting radiation. The number of heating components (3) is sequentially divided into several variable temperature groups according to groups to control the temperature of the heating components (3) under each variable temperature group, and perform a baking process synchronously with the heating roller (2); Set a radiation receiving and emitting plate (4) between the heating roller (2) and the several variable temperature groups. The radiation receiving and emitting plate (4) is used to absorb the radiation emitted by each heating component (3) and emit radiation to the pole piece (1) on the roller surface of the heating roller (2).
2. The method for auxiliary heating of the pole piece by using blackbody radiation to generate a multi-frequency radiation thermal field as claimed in claim 1, wherein The heating component (3) includes a radiation tube (31), which is used to emit radiation light towards the absorption side of the radiation receiving and emitting plate (4).
3. The method for auxiliary heating of the pole piece by using blackbody radiation to generate a multi-frequency radiation thermal field as claimed in claim 2, wherein The heating component (3) further includes an enclosed glass cover (32), and the radiation tube (31) is arranged inside the enclosed glass cover (32).
4. The method for auxiliary heating of the pole piece by using blackbody radiation to produce a multi-frequency radiation thermal field as claimed in claim 1, wherein The radiation light source in the radiation tube (31) is at least one of infrared light or ultraviolet light.
5. The method for auxiliary heating of the pole piece by using blackbody radiation to generate a multi-frequency radiation thermal field according to claim 1, characterized in that, The radiation receiving and emitting plate (4) is made of frosted glass.
6. The method for auxiliary heating of the pole piece by using blackbody radiation to generate a multi-frequency radiation thermal field as claimed in claim 1, wherein The radiation receiving and emitting plate (4) is made of a carbon-based wave-absorbing material. The absorption side of the radiation receiving and emitting plate (4) is coated with a coating with high absorption rate and low emissivity, and the emission side of the radiation receiving and emitting plate (4) is coated with a high emissivity coating.
7. The method for auxiliary heating of the pole piece by using blackbody radiation to produce a multi-frequency radiation thermal field as claimed in claim 6, characterized in that, The coating with high absorption rate and low emissivity is indium tin oxide, and the high emissivity coating is a black paint coating.
8. The method for auxiliary heating of the pole piece by using blackbody radiation to generate a multi-frequency radiation thermal field as claimed in claim 1, wherein The radiation receiving and emitting plate (4) is made of a carbon-based wave-absorbing material, and both the absorption side and the emission side of the radiation receiving and emitting plate (4) are coated with a black paint coating.
9. The method for auxiliary heating of the pole piece by using blackbody radiation to produce a multi-frequency radiation heat field as claimed in claim 1, wherein, The shape of the radiation receiving and emitting plate (4) is adapted to the shape of the roller surface of the heating roller (2).
10. The method for auxiliary heating of the pole piece by using blackbody radiation to produce a multi-frequency radiation thermal field as claimed in claim 1, wherein Perform a tempering process on the baked and dried pole piece (1), and the tempering temperature is 70 - 220 degrees Celsius.