A flexible carbon material electrothermal film

Abstract

This invention relates to the field of electrothermal conversion device technology, and aims to provide a flexible carbon material electrothermal film, comprising a heating layer, an encapsulation layer, and a protective layer. The encapsulation layer is made of a flexible, insulating, and heat-resistant material, which encapsulates the heating layer. The protective layer is fitted over the encapsulation layer. By controlling the thickness and density of the heating layer in the carbon material electrothermal film, the overall resistance of the carbon material electrothermal film is made to meet a preset accuracy range, thereby improving the overall yield. Furthermore, by combining it with specific materials, the relative radiation intensity of the entire wavelength of the electrothermal film is greater than 0.3, and the overall far-infrared radiation intensity is softer, making it easier for the human body to absorb.

Description

Technical Field

[0001] This invention belongs to the technical field of electrothermal conversion devices, and particularly relates to a flexible carbon material electrothermal film. Background Technology

[0002] Currently, heating devices in car seats mainly use metal heating wires, which connect to the vehicle's power supply to achieve electrothermal conversion. However, metal heating wires have drawbacks such as being relatively rigid and producing uneven heating. Carbon material heating films are flexible films obtained through high-temperature treatment after slurry coating. They have advantages such as being soft, having a large heating area, uniform heating, high normal emissivity, and fast heating speed, and can solve the problems existing in current metal heating wires.

[0003] Therefore, those skilled in the art have considered using carbon material heating films to replace metal heating wires as heating components in car seats. However, in practical applications, the resistance of carbon material heating films is difficult to control, and the resistance of different samples from the same batch of carbon material heating films can vary significantly. Furthermore, according to existing research, the far-infrared effect of carbon material heating films can activate human cells and promote human health. However, actual testing has revealed that carbon material heating films experience significant attenuation at certain wavelengths, and stray wavelengths can also affect the resonance effect between far-infrared radiation and the human body. These problems hinder the application of carbon material heating films in car seats. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible carbon material heating film. By controlling the thickness and density of the heating layer in the carbon material heating film, the overall resistance of the carbon material heating film meets a preset accuracy range, thereby improving the overall yield. The flexible carbon material heating film includes a heating layer, an encapsulation layer, and a protective layer. The encapsulation layer is made of a flexible, insulating, and heat-resistant material, which encapsulates the heating layer. The protective layer is fitted outside the encapsulation layer. The relationship between the thickness and density of the heating layer is as follows: When K satisfies the condition ,and At that time, the numerical relationship of the resistivity of the heating layer satisfies Where d1 is the actual thickness of the heating layer, d0 is the preset thickness of the heating layer, P is the measured density of the heating layer, ρ1 is the measured resistivity of the heating layer, and ρ0 is the theoretical resistivity of the heating layer.

[0005] In a further technical solution, the heating layer is selected from artificial graphite thermal conductive film, natural graphite thermal conductive film, and graphene film; preferably, the carbon material heating layer is selected from graphene film. Currently, the artificial graphite film, natural graphite thermal conductive film, or graphene film used in the heating layer are basically prepared by slurry coating, high-temperature treatment, and calendering. Therefore, the uniformity of the coating slurry greatly affects the performance of various parts of the heating layer, including but not limited to thermal conductivity and electrical properties. In practical applications, significant differences in resistance have been found within the same batch of heating layers. Therefore, the difference between the actual resistivity and the theoretical resistivity of the heating layer needs to be controlled within 10% to meet the stability requirements of the actual heating temperature of the product. Theoretically, many factors affect resistivity. Current research has identified influencing factors including material type, temperature, impurity content, crystal structure and defects, and mechanical deformation. Therefore, the resistivity of a material is comprehensively affected by its internal structure, composition, processing technology, and external environment (especially temperature). Carbon material heating films differ from metal materials; their raw materials and processing technology make it more difficult to control the resistivity of carbon material heating films. This application provides a carbon material heating film with resistivity error control within ≤10%. By controlling the thickness and density of the carbon material heating film as the heating layer within a certain range, a carbon material heating film with accurate resistivity can be obtained.

[0006] In some preferred embodiments, the measured density P of the heating layer is set to 1.80 g / cm³. 3 —2.20g / cm 3 Preferably, the density of the heating layer is set to 1.90 g / cm³. 3 —2.10g / cm 3 The numerical relationship of the resistivity of the heating layer satisfies The preset thickness d0 of the heating layer is set to 30-100 μm. This is based on existing formulas relating resistance and resistivity. Where R is the resistance value, ρ is the resistivity, L is the trace length of the heating layer, w is the linewidth of the heating layer, and d is the thickness of the heating layer. Therefore, theoretically, controlling the trace length, width, and thickness of the heating layer can achieve the goal of controlling resistance and resistivity. However, research has found that in reality, resistivity and resistance are also related to the density of the heating layer. Due to the inherent characteristics of the material, the physical properties of heating layers made from carbon materials differ from those of metals. This can be observed in the SEM images of the heating layer cross-section, which show numerous micron- and nano-sized pores. Furthermore, due to the manufacturing process of the heating layer, the density can vary significantly in different areas. Based on these findings, the technical problem of uncontrollable heating layer resistivity can be solved by eliminating carbon material films with unstable density and thickness during the quality control process.

[0007] In some preferred embodiments, the measured density P of the heating layer is set to 1.80 g / cm³. 3 —2.20g / cm 3 Preferably, the measured density of the heating layer is set to 1.90 g / cm³. 3 —2.10g / cm 3 Examples that can be listed include 1.80 g / cm³. 3 1.83g / cm 3 1.85g / cm 3 1.88g / cm 3 1.90g / cm 3 1.93g / cm 3 1.95g / cm 3 1.98g / cm 3 2.05g / cm 3 2.08 g / cm 3 2.10 g / cm 3 2.13 g / cm 3 2.15g / cm 3 2.18 g / cm 3 2.20g / cm 3 The density of the heating layer is calculated by dividing its mass by its volume. During the quality control stage, a sample of a predetermined area is taken, and the thickness is measured to calculate the density. After extensive data and testing analysis, it was found that as long as the ratio between density and thickness meets the predetermined range, the resistivity deviation can be controlled within an acceptable range.

[0008] In some preferred embodiments, the preset thickness d0 of the heating layer is set to 30-100 μm, and preferably, the preset thickness d0 of the heating layer is set to 40-80 μm. Examples of thicknesses include 30 μm, 35 μm, 37 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 55 μm, 57 μm, 60 μm, 62 μm, 65 μm, 70 μm, 72 μm, 75 μm, 80 μm, 82 μm, 85 μm, 87 μm, 90 μm, 92 μm, 95 μm, 97 μm, and 100 μm. Thickness is one of the parameters affecting resistance. Heating layers of different thicknesses can be selected to match the preset resistance. As long as the ratio between thickness and density meets a predetermined range, the resistivity deviation can be controlled within an acceptable range. In practice, it has been found that when the heating layer is made of carbon material, thickness not only affects the resistance of the heating layer, but also, when the thickness and density meet certain ranges, the resistivity of the heating layer.

[0009] In some preferred embodiments, the relative radiation intensity of the carbon material electrothermal film is greater than 0.3 in the infrared radiation wavelength range of 5.5μm-15.0μm. The human body emits far-infrared rays constantly; measurements show that the wavelength of far-infrared rays emitted by the human body is around 9.6μm. The wavelengths of far-infrared rays (5.6-15μm) overlap with the wavelengths emitted by the human body (the average human body temperature is 36.5℃, which translates to approximately 9.4 micrometers), and their frequency ranges are within the same range. Therefore, this can activate the cellular molecules within the human body; this phenomenon is called resonance. It can activate cells, promote blood circulation, accelerate metabolism, and enhance the body's own immunity. While graphene is often touted for its far-infrared effects, actual measurements have revealed that when the heating layer is a graphene film, there is a significant attenuation of infrared radiation within the 3.5-5.0 μm wavelength range. Furthermore, attenuation also occurs at a specific wavelength within the 5.0-9.5 μm range, indicating wavelength disorder that negatively impacts the far-infrared effect. When combined with an encapsulation layer, the infrared radiation effect is significantly improved. The wavelength variation within the 5.5-14.5 μm range is more gradual, and the overall relative radiation intensity is greater than 0.3, making it more conducive to human absorption.

[0010] In some preferred embodiments, the carbon content of the heating layer is greater than or equal to 95%, and preferably, the carbon content of the carbon material in the heating layer is greater than or equal to 98%. Examples of carbon contents include 95%, 96%, 97%, 98%, and 99%. Carbon content is one of the factors determining the final thickness and density of the heating layer; a higher carbon content will result in a greater final thickness and density. This is mainly because during the high-temperature processing, substances other than carbon are removed and released as gases. Therefore, a higher carbon content makes the thickness and density of the final product more controllable.

[0011] In some preferred embodiments, the encapsulation layer is made of a waterproof and heat-resistant fabric with a total RGB value of less than 100, preferably less than 50. The fabric color also affects the relative radiation intensity of the infrared radiation wavelength. When the fabric color is relatively dark, it has a significant boosting effect on the relative radiation intensity of the heating layer. Especially when the total RGB value of the fabric color is less than 50, the carbon material heating film exhibits a significant increase in radiation intensity within the infrared radiation wavelength range (3.5-5.0 μm), resulting in a more gradual change in the wavelength range that resonates with the human body, leading to better absorption by the human body.

[0012] In some preferred embodiments, the average surface roughness Ra of the heating layer is ≥ 0.357 μm, and preferably, the average surface roughness Ra of the heating layer is greater than or equal to 0.450 μm. Examples of such average surface roughness settings for the heating layer include 0.357 μm, 0.368 μm, 0.379 μm, 0.412 μm, 0.448 μm, 0.463 μm, 0.479 μm, 0.498 μm, 0.507 μm, 0.532 μm, 0.563 μm, 0.598 μm, 0.664 μm, and 0.716 μm.

[0013] In some preferred embodiments, the protective layer is made of non-woven fabric, and its air permeability is set to 400-800 mm / s, preferably 400-600 mm / s. Examples of air permeability settings for the protective layer include 400 mm / s, 420 mm / s, 450 mm / s, 480 mm / s, 500 mm / s, 520 mm / s, 560 mm / s, 580 mm / s, 600 mm / s, 630 mm / s, 660 mm / s, 680 mm / s, 700 mm / s, 740 mm / s, 780 mm / s, and 800 mm / s. The protective layer is directly fitted over the encapsulation layer. Although it does not directly affect the relative radiation intensity, the air permeability of the protective layer has a dilution effect on the relative radiation intensity. In addition, the protective layer also needs to have a certain tensile strength. Low air permeability will improve tensile strength, while high air permeability will dilute the intensity of far-infrared radiation. The level of air permeability depends on factors such as the material's pore structure, pore size distribution, and pore connectivity. Therefore, moderate air permeability is necessary to balance tensile strength and not excessively affect the far-infrared radiation effect. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is the relative radiation intensity test spectrum of Embodiment 1 of the present invention.

[0016] Figure 2 This is the relative radiation intensity test spectrum of Comparative Example 1 of the present invention.

[0017] Figure 3 This is the relative radiation intensity test spectrum of Comparative Example 2 of the present invention. Detailed Implementation

[0018] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0020] A flexible carbon material electrothermal film includes a heating layer, an encapsulation layer, and a protective layer. The encapsulation layer is made of a flexible, insulating, and heat-resistant material, which encapsulates the heating layer. The protective layer is fitted over the encapsulation layer. In this embodiment, the heating layer is a graphene film purchased from Yunnan Yuntian Morui, and the graphene film has a carbon content greater than 98%. Based on the required heating temperature of the product, the theoretical power density required for the carbon material electrothermal film is 300 W / m². 2 The carbon material heating film has a heating area of ​​0.5㎡, therefore its power is 150W. The power supply voltage to the carbon material heating film is 13.5V. Based on the conversion formula between resistance and power, the designed resistance value R of the heating layer is calculated to be 1.2150 Ω. The graphene thermally conductive film, used as the heating layer, has a theoretical resistivity of 1.308 × 10⁻⁸ Ω. -6 Ω·m. Based on theoretical values, the trace length of the heating layer is set to 1.951 m, and the line width of the heating layer is 5.0*10. -2 m, the thickness of the heating layer is 42μm; in actual fabrication, the thickness error of the heating layer needs to be within ±2μm.

[0021] The heating layer is obtained by die-cutting a carbon material film. The carbon material film itself is obtained through slurry coating and high-temperature treatment, resulting in a relatively thin layer with a certain degree of variation. Three samples of flexible carbon material electric heating films were randomly selected from the same batch for testing. After measurement, the data was recorded. Samples measuring 2*2cm were cut from each of the three samples, and their mass was weighed. The measured density was calculated using a formula. Calculate the ratio K between the actual thickness and the measured density.

[0022]

[0023] The test results showed that the measured resistances were 1.2325Ω, 1.2684Ω, and 1.2706Ω, respectively. The difference in resistivity calculated based on the actual thickness and resistance data was less than 10%, which meets the requirements of the preset resistivity error range. Analysis of samples 1-3 revealed that the deviation between the measured thickness and the preset thickness of samples 1-3 was within 2μm, and the density range was within 1.8g / cm³. 3 Up to 2.2 g / cm 3 between.

[0024] In this embodiment, the surface roughness of the heating layer is greater than 0.500 μm, and the surface roughness is mainly determined by the carbon material film coating substrate. The encapsulation layer uses a waterproof and heat-resistant fabric, specifically a polyester fiber fabric, i.e., commercially available polyester fabric. The fabric color needs to be dark; more specifically, the RGB value of the fabric color should be less than 50. In this embodiment, the polyester fabric color used is RAL 9018, with corresponding RGB values ​​of R=7, G=7, B=7, and a total value of 21. The protective layer uses a non-woven fabric, and the air permeability of the protective layer is greater than or equal to 500 mm / s. The selection of the air permeability of the protective layer needs to consider both tensile strength and not excessively affect the far-infrared radiation effect. The far-infrared radiation effect is tested according to the measurement methods for the effective radiation energy ratio, distribution temperature, and radiation wavelength range of the heater in Chapter 20 of the national standard GB / T 7287-2008 "Test Methods for Infrared Radiation Heaters". The results are as follows: Figure 1 As shown, the relative radiation intensity of the carbon material electrothermal film is greater than 0.3 in the infrared radiation wavelength range of 5.5μm-15.0μm.

[0025] Example 2

[0026] The difference between this embodiment and Embodiment 1 is that the thickness of the heating layer is 45 μm. Based on the required heating temperature of the product, the theoretical power density required for the carbon material heating film is 300 W / m². 2 The heating area is 0.5㎡, and the power is 150W. The power supply voltage to the carbon material heating film is 13.5V. According to the conversion formula between resistance and power, the design resistance value R of the heating layer is calculated to be 1.2150 Ω.

[0027] Based on theoretical values, the wiring length of the heating layer was reset to 2.090m, and the line width of the heating layer was 5.0*10. -2 Three samples of flexible carbon material electrothermal films, randomly selected from the same batch, were tested. The thickness was measured, and the resistance at each point was measured and recorded after applying current. After measurement, 2*2cm samples were cut from each of the three samples, their mass was weighed, and the measured density was calculated using a formula. Calculate the ratio K between the actual thickness and the measured density.

[0028]

[0029] The test results showed that the measured resistances of samples 1-3 were 1.2825Ω, 1.2984Ω, and 1.3806Ω, respectively. The resistivity difference between samples 1 and 2 was less than 10%, while the resistivity difference of sample 3 exceeded 10%. Analysis revealed that the thickness difference between samples 1-3 and the preset thickness was less than 2μm, and the actual measured density of samples 1 and 2 was greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 The density of sample 3 is less than 1.8 g / cm³. 3 Furthermore, the measured resistivity difference of sample 3 is greater than 10%, which does not meet the requirements of the preset resistivity error range.

[0030] Example 3

[0031] The difference between this embodiment and Embodiment 1 is that the thickness of the heating layer is 47 μm. Based on the required heating temperature of the product, the theoretical power density required for the carbon material heating film is 300 W / m². 2 The heating area is 0.5㎡, and the power is 150W. The power supply voltage to the carbon material heating film is 13.5V. Based on the conversion formula between resistance and power, the design resistance R of the heating layer is calculated to be 1.2150 Ω. According to theoretical values, the wiring length of the heating layer is set to 2.183m, and the line width is 5.0*10. -2 m. Three samples of flexible carbon material electrothermal films, randomly selected from the same batch, were tested. The thickness was measured, and the resistance at each location was measured and recorded after energizing. After measurement, 2*2cm samples were cut from the three different box areas, and their mass was weighed. The measured density was calculated using a formula. Calculate the ratio K between the actual thickness and the measured density.

[0032]

[0033] The test results showed that the measured resistances of samples 1-3 were 1.2754Ω, 1.0183Ω, and 1.2923Ω, respectively. The resistivity difference between samples 1 and 3 was less than 10%, while the resistivity difference of sample 3 exceeded 10%. Analysis revealed that the densities of samples 1-3 ranged from 1.8 to 2.2. The deviations between the measured and preset thicknesses of samples 1 and 3 were within 2μm. The measured thickness of sample 2 was 49.12μm, which was greater than 2μm from the preset thickness. Furthermore, the resistivity of sample 2 deviated from the theoretical resistivity by more than 10%, failing to meet the error range requirements.

[0034] Example 4

[0035] The difference between this embodiment and Embodiment 1 is that the thickness of the heating layer is 30 μm. While ensuring that the power density and resistance remain unchanged, the trace length of the heating layer was reset to 2.229 m according to theoretical values. Three samples were selected for testing, and the measured data are as follows:

[0036]

[0037] The test results showed that the measured resistances of samples 1-3 were 1.2755Ω, 1.2147Ω, and 1.3979Ω, respectively. The resistivity errors of samples 1 and 2 were within the acceptable range, with a resistivity difference of less than 10%. Analysis revealed that the deviation between the measured and predicted thicknesses of samples 1 and 2 was within 2μm, and the actual density was greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 Although the deviation between the measured and predicted thickness of sample 3 is also within 2 μm, the actual density of sample 3 is 2.235 g / cm³. 3 The actual resistivity difference is 11.2%, which exceeds the error requirement range.

[0038] Example 5

[0039] The difference between this embodiment and Embodiment 1 is that the thickness of the heating layer is 80 μm. While ensuring that the power density and resistance remain unchanged, the width of the heating layer was reset to 0.030 m and the trace length to 2.229 m according to theoretical values. Three samples were selected for testing, and the measured data are as follows:

[0040]

[0041] The test results showed that the measured resistances of samples 1-3 were 1.2310Ω, 1.2265Ω, and 1.2859Ω, respectively. The resistivity errors of samples 1-3 were within the acceptable range, with a resistivity difference of less than 10%. Analysis revealed that the deviation between the measured and predicted thicknesses of samples 1-3 was within 2μm, and the actual density was greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 .

[0042] Example 6

[0043] The difference between this embodiment and Embodiment 1 is that the thickness of the heating layer is 100 μm. While ensuring that the power density and resistance remain unchanged, the width of the heating layer was reset to 0.020 m and the trace length to 1.858 m according to theoretical values. Three samples were selected for testing, and the measured data are as follows:

[0044]

[0045] The test results showed that the measured resistances of samples 1-3 were 1.2641Ω, 1.2355Ω, and 1.2199Ω, respectively. The resistivity errors of samples 1-3 were within the acceptable range, with a resistivity difference of less than 10%. Analysis revealed that the deviation between the measured and predicted thicknesses of samples 1-3 was within 2μm, and the actual density was greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 .

[0046] Example 7

[0047] The difference between this embodiment and Embodiment 1 is that the heating layer uses an artificial graphite film with a thickness of 42 μm. In actual fabrication, the thickness error of the heating layer needs to be within ±2 μm. The theoretical resistivity of the artificial graphite film is 1.14 × 10⁻⁶. -6 Ω·m. Based on the required heating temperature of the product, the theoretical power density required for the carbon material heating film is 300 W / m. 2 The heating area of ​​the carbon material heating film is 0.5㎡, therefore the power is 150W. The power supply voltage to the carbon material heating film is 13.5V. Based on the conversion formula between resistance and power, the design resistance R of the heating layer is calculated to be 1.2150 Ω. According to theoretical values, the trace length of the heating layer is set to 2.238 m, and the trace width is 5.0*10 mm. -2 m. The measurement results are as follows:

[0048]

[0049] The test results showed that the measured resistances of samples 1-3 were 1.2441Ω, 1.2346Ω, and 1.2789Ω, respectively. The resistivity errors of samples 1-3 were within the acceptable range, with a resistivity difference of less than 10%. Analysis revealed that the deviation between the measured and predicted thicknesses of samples 1-3 was within 2μm, and the actual density was greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 .

[0050] Example 8

[0051] The difference between this embodiment and Embodiment 1 is that the heating layer is a 42μm thick natural graphite thermal conductive film. The theoretical resistivity of the natural graphite thermal conductive film is 6.5*10⁻⁶. -6 Ω·m. Based on the required heating temperature of the product, the theoretical power density required for the carbon material heating film is 300 W / m. 2The heating area of ​​the carbon material heating film is 0.5㎡, therefore the power is 150W. The power supply voltage to the carbon material heating film is 13.5V. Based on the conversion formula between resistance and power, the design resistance R of the heating layer is calculated to be 1.2150 Ω. According to theoretical values, the wiring length of the heating layer is set to 0.785 m, and the line width is 10*10 mm. -2 m. The measurement results are as follows:

[0052]

[0053] The test results showed that the measured resistances of samples 1-3 were 1.2676Ω, 1.2554Ω, and 1.2923Ω, respectively. The resistivity errors of samples 1 and 2 were within the acceptable range, with a resistivity difference of less than 10%. Analysis revealed that the deviation between the measured and predicted thicknesses of samples 1-3 was within 2μm, and the actual densities were all greater than 1.8g / cm³. 3 Less than 2.2 g / cm³ 3 The resistivity of sample 3 was 1.2923 Ω. After conversion, the resistivity difference was found to be greater than 10%, exceeding the error range. Although the thickness of sample 3 was within the deviation range of ±2 μm, the density measurement result was 1.776 g / cm³. 3 The actual resistivity difference does not meet the error requirement range.

[0054] The measured thickness and density data obtained from Examples 1-8 revealed that regardless of whether the heating layer material is graphene thermal conductive film, artificial graphite film, or natural graphite thermal conductive film, as long as the density is greater than 1.8 g / cm³, the thermal conductivity will be optimal. 3 Less than 2.2 g / cm³ 3 Meanwhile, when the measured thickness and the preset thickness are within a certain range, the difference in resistivity can be controlled within 10%. A pattern is found where the relationship between the thickness and density of the heating layer is... When K satisfies the condition ,and At that time, the numerical relationship of the resistivity of the heating layer satisfies That is, the error in the resistivity of the heating layer is within 10%.

[0055] Therefore, in the actual production management process, it is only necessary to control the ratio of thickness to density to achieve the effect of controlling the resistance and resistivity of flexible carbon material electrothermal film.

[0056] Based on the above pattern, samples with resistivity differences within 10% in Examples 1-8 all conform to the pattern; samples with resistivity differences greater than 10% are Sample 2 of Example 2, Sample 2 of Example 3, Sample 3 of Example 4, and Sample 3 of Example 8. According to the above empirical formula, the K value range of Sample 3 of Example 2 should satisfy 0.452 ≤ K ≤ 0.553. The K value of Sample 3 of Example 2 is 0.556, exceeding the limit. Similarly, the K value range of Sample 2 of Example 3 should satisfy 0.475 ≤ K ≤ 0.581. Although the K value is 0.522, which is within the limit, it does not meet the requirement. The condition is that the thickness error range is greater than 2 μm. For sample 3 in Example 4, the K value range needs to satisfy 0.439 ≤ K ≤ 0.537. The actual K value of sample 3 in Example 4 is 0.432, which does not meet the specified range. For sample 3 in Example 8, the K value range needs to satisfy 0.447 ≤ K ≤ 0.547. The actual K value of sample 3 in Example 8 is 0.554, which exceeds the specified range for K value.

[0057] Example 9

[0058] The difference between this embodiment and Embodiment 1 is that the color of the fabric selected for the encapsulation layer has an RGB value of less than 50. In this embodiment, the polyester fabric color used is RAL 9011, with corresponding RGB values ​​of R=28, G=28, B=28, and a total value of 84.

[0059] Example 10

[0060] The difference between this embodiment and Embodiment 1 is that the color of the fabric selected for the encapsulation layer has an RGB value of less than 50. In this embodiment, the polyester fabric color used is RAL 9017, with corresponding RGB values ​​of R=30, G=30, B=30, and a total value of 90.

[0061] Comparative Example 1

[0062] The carbon material of the heating layer is replaced with a metal heating wire, and the power density is 300W / m. 2 The heating area is 0.5㎡. Far-infrared radiation effect was tested according to Chapter 20 of the national standard GB / T 7287-2008, "Test Methods for Infrared Radiation Heaters," which specifies the measurement methods for the effective radiation energy ratio, distribution temperature, and radiation wavelength range of the heater. The test results are as follows: Figure 2 As shown, the infrared radiation wavelength of the metal heating wire does not follow a clear pattern. When a person approaches the human body's radiation wavelength, that is, within the range of infrared radiation wavelength (5.5-14.5μm), the wavelength change is relatively disordered.

[0063] Comparative Example 2

[0064] Using a carbon material heating film (graphene thermally conductive film) with a preset resistance of 1.2150 Ω (without encapsulation layer), the theoretical power density required for the carbon material heating film is 300 W / m. 2 The heating area of ​​the carbon material heating film is 0.5㎡, therefore the power is 150W. The power supply voltage to the carbon material heating film is 13.5V. The far-infrared radiation effect was tested according to Chapter 20 of the national standard GB / T 7287-2008, "Test Methods for Infrared Radiation Heaters," which specifies the measurement methods for the effective radiation energy ratio, distribution temperature, and radiation wavelength range of the heater. The test results are as follows. Figure 3 As shown, when graphene thermal conductive film is used as the heating layer, its infrared radiation wavelength (5.5-14.5μm) is not stable, especially in the wavelength range of 3.5-8.0, where multiple unstable fluctuations occurred.

[0065] From the far-infrared radiation effect tests of Example 1, Comparative Example 1, and Comparative Example 2, it can be found that ordinary metal heating wires resonate within the wavelength range of infrared radiation wavelengths (5.5-14.5 μm) that occur in the human body. Figure 2 The results showed significant fluctuations, and the overall changes were quite chaotic. Irregular variations in radiation intensity are detrimental to human absorption. Further verification through experiments in Comparative Example 2 revealed that when the ordinary metal heating wire was replaced with a graphene thermally conductive film as the heating material, as... Figure 3 Although the overall variation is more regular, fluctuations occur in certain wavelength ranges from 3.5 to 8.0 nm. After using the encapsulation layer composite, the encapsulation layer has a reinforcing effect on the wavelength range where the heating layer attenuates, resulting in a more gradual change in the overall far-infrared radiation intensity.

[0066] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A flexible carbon material electrothermal film, comprising a heating layer, an encapsulation layer, and a protective layer, characterized in that: The encapsulation layer is made of a flexible, insulating, and heat-resistant material, which encapsulates the heating layer. The protective layer is fitted over the encapsulation layer. The relationship between the thickness and density of the heating layer is as follows: When K satisfies the condition ,and At that time, the numerical relationship of the resistivity of the heating layer satisfies Where d1 is the actual thickness of the heating layer, d0 is the preset thickness of the heating layer, P is the measured density of the heating layer, ρ1 is the measured resistivity of the heating layer, and ρ0 is the theoretical resistivity of the heating layer.

2. The flexible carbon material electrothermal film according to claim 1, characterized in that: The heating layer is made of artificial graphite thermal conductive film, natural graphite thermal conductive film or graphene film.

3. The flexible carbon material electrothermal film according to claim 2, characterized in that, The heating layer is made of graphene film.

4. The flexible carbon material electrothermal film according to claim 1, characterized in that: The measured density P of the heating layer was set to 1.80 g / cm³. 3 —2.20g / cm 3 .

5. The flexible carbon material electrothermal film according to claim 4, characterized in that: The measured density P of the heating layer was set to 1.90 g / cm³. 3 —2.10g / cm 3 .

6. The flexible carbon material electrothermal film according to claim 1, characterized in that: The preset thickness d0 of the heating layer is set to 30-100μm.

7. The flexible carbon material electrothermal film according to claim 1, characterized in that: The preset thickness d0 of the heating layer is set to 40-80μm.

8. The flexible carbon material electrothermal film according to claim 1, characterized in that: The relative radiation intensity of the carbon material electrothermal film is greater than 0.3 in the infrared radiation wavelength range of 5.5μm-15.0μm.

9. The flexible carbon material electrothermal film according to claim 8, characterized in that: The carbon content of the heating layer is greater than or equal to 95%.

10. The flexible carbon material electrothermal film according to claim 9, characterized in that: The carbon content of the heating layer is greater than or equal to 98%.

11. The flexible carbon material electrothermal film according to claim 8, characterized in that: The encapsulation layer is made of waterproof and heat-resistant fabric, and the sum of the RGB values ​​of the fabric's colors is less than 100.

12. The flexible carbon material electrothermal film according to claim 11, characterized in that: The sum of the RGB values ​​of the fabric color is less than 50.

13. The flexible carbon material electrothermal film according to claim 8, characterized in that: The average surface roughness Ra of the heating layer is ≥0.357 μm.

14. The flexible carbon material electrothermal film according to claim 13, characterized in that: The average surface roughness Ra of the heating layer is greater than or equal to 0.450 μm.

15. The flexible carbon material electrothermal film according to claim 8, characterized in that: The protective layer is made of non-woven fabric, and the air permeability of the protective layer is set to 400-800 mm / s.

16. The flexible carbon material electrothermal film according to claim 15, characterized in that: The air permeability of the protective layer is set to 400-600 mm / s.

Images