Heat-resistant PI resin / fiber composite packaged infrared electric heating assembly and preparation method thereof

Abstract

The invention provides a heat-resistant polyimide (PI) resin / fiber composite packaged infrared electric heating assembly and a preparation method thereof. The infrared electric heating assembly comprises a montmorillonite fiber fabric electric heating piece and PI resin / fiber composite packaging materials laid on the upper surface and the lower surface of the electric heating piece. The packaging material and the sealed material are firmly combined and integrally formed, and roll-to-roll production can be theoretically achieved. The packaging thickness and the voltage-resistant electric leakage performance of the infrared electric heating assembly can be regulated and controlled through design. Compared with other packaging methods such as gluing in similar technical files, the packaging method has the advantages of being airtight, resistant to high-temperature aging and firm and having certain mechanical strength.

Description

Technical Field

[0001] The invention belongs to the field of composite packaged electric heating components, and in particular relates to a heat-resistant polyimide (PI) resin / fiber composite packaged infrared electric heating component and a preparation method thereof. Background Art

[0002] Infrared electric heating, also known as electric infrared radiation heating or electric infrared heating, refers to an electric heating method that uses infrared radiation generated by electric energy to transfer heat energy. Its equipment has a simple structure, low cost, easy maintenance, small footprint, and easy to achieve continuous automated production. The infrared radiation generated by infrared electric heating is an electromagnetic wave that can penetrate a certain depth into the surface of the heated material, and basically does not heat the air and other media in the space. Therefore, it has the advantages of high thermal efficiency, fast heating speed, low power consumption, high heating quality, and good working environment. These characteristics are particularly evident in the low temperature (50-650℃) section, making infrared electric heating particularly suitable for heating in the low temperature section below 650℃.

[0003] Infrared radiation is generally divided into two bands: near infrared and far infrared. Since most organic compounds have strong absorption characteristics for far infrared rays, most of the heating, dehydration, drying and curing operations in the automated assembly lines of industries such as coating, printing and dyeing, textiles, food, papermaking, household appliances, and medical equipment use far infrared rays with a wavelength range of 2.5 to 30 μm for heating.

[0004] Graphene infrared electrothermal refers to the application of graphene materials in infrared electrothermal technology. Graphene has the excellent properties of being light, strong, conductive, thermally conductive, flexible and transparent. It is an ideal infrared emitter similar to a "gray body" with an infrared emissivity of >0.90. Its emission wavelength is concentrated in the range of 6-14μm, which is in the far-infrared band, making it have huge application potential in the above-mentioned infrared electrothermal field.

[0005] Monene fiber fabric is a new type of fiber fabric formed by directly growing a thin layer of graphene on the surface of the fiber fabric using the vapor deposition method. It is a new type of material that uses continuous graphene sheets with atomic thickness to achieve practical applications on a widely used fiber fabric material carrier. By loading continuous electrodes on the opposite sides of the monene fiber fabric and applying voltage, a conductive path can be constructed in a direction perpendicular to the electrode, and the monene fiber fabric and the electrode as a whole can be used as an infrared emitting component of an infrared electric heating component. Although the monene fiber fabric itself has good electrothermal properties, in the presence of oxygen, the thin graphene layer on its surface will oxidize under high temperature conditions, causing the material's electrothermal properties to gradually lose. Therefore, it is necessary to perform oxygen-proof packaging on the monene fiber fabric carrying the electrode.

[0006] Polyimide (PI) is an aromatic heterocyclic polymer compound with an imide chain link in its molecular structure. It is one of the most heat-resistant engineering plastics currently available. PI can be used as a resin and is widely used in the fields of aviation, aerospace, microelectronics, nanotechnology, liquid crystal, laser, etc. Due to its outstanding characteristics in performance and synthesis, PI has great application prospects whether as a structural material or as a functional material.

[0007] The patent document with application number CN202410078978.3, publication number CN117769068A, and invention name "Fabric-based laser-induced graphene electrically heated flexible film, preparation method and application" provides a fabric-based laser-induced graphene electrically heated flexible film, preparation method and application, which belongs to the technical field of electric heating materials. The fabric-based laser-induced graphene electrically heated flexible film provided by the invention includes a fabric-based laser-induced graphene, an electrode and a flexible packaging material, wherein the electrode is arranged at both ends of the fabric-based laser-induced graphene, and the flexible packaging material is encapsulated on the upper surface and the lower surface of the fabric-based laser-induced graphene. The fabric-based laser-induced graphene electrically heated flexible film provided by the invention is convenient for large-area heating, and has a high heating rate, low cost, mild preparation environment, green and environmentally friendly, and no waste gas and sewage are generated during the entire production process. However, the fabric-based laser-induced graphene electrically heated flexible film provided by the invention cannot meet the heating conditions of 300°C.

[0008] The utility model patent CN214228494U provides a graphene heating sheet packaging component, but the packaging described therein only refers to sandwiching the graphene heating sheet with layers of tempered glass and polyimide fiber cloth, and then sealing the edge of the tempered glass with sealant. Its application field belongs to sealing the heating element by mechanical means, rather than encapsulating the heating element by a composite material preparation method. The invention patent CN116648043A provides a graphene touch-skin thermal control device, and the packaging described therein refers to coating the graphene core with a polyimide film and sealing the edge of the graphene core, which also does not belong to the category of encapsulating the heating element by a composite material preparation method. The technical solutions of these two patents do not involve the mutual penetration and anchoring of polyimide resin and graphene network and its carrier. Similarly, the upper limit of the operating temperature and the corresponding life of the heating devices provided by these two patents are not mentioned in their patent documents.

[0009] In the prior art, there are examples of composite packaging of monene fiber fabrics carrying electrodes with organic polymer resins such as epoxy resin and silicone resin. However, these packaging schemes are based on the infusion and penetration of liquid resin into the fiber fabric, and then solidification under normal pressure or pressurized conditions to form a resin-fiber composite electric heater. The use effect of these packaged monene fiber fabric components is still good under the condition of heating temperature below 200°C. However, the long-term high temperature resistance of the resin used in these composite packaging methods is insufficient, so it cannot meet the long-term temperature resistance requirement of 300°C. In addition, in some applications, the surface heating uniformity of the encapsulated heating components is not high, and there are several hot spots.

[0010] In the prior art, PI with excellent heat resistance has not yet been applied to the field of composite packaging electric heating components, so as to improve its applicable electric heating temperature range while well supporting the electric heating components. Summary of the invention

[0011] The purpose of the present invention is to provide an infrared electric heating component with heat-resistant PI resin / fiber composite packaging, which can withstand a high temperature of 300°C for a long time. The two technical means of using monene fiber fabric as a carrier of graphene conductive network introduced into the infrared electric heating device and using a thin metal sheet welded at the end of the copper-sprayed electrode as the electrode lead-out terminal are both well compatible with the existing composite material manufacturing process without making major changes to its molding process conditions.

[0012] The heat-resistant PI resin / fiber composite encapsulated infrared electric heating component provided by the present invention comprises a monene fiber fabric electric heating sheet and a PI resin / fiber composite encapsulation material laid on the upper and lower surfaces of the electric heating sheet; Wherein, the monene fiber fabric electric heating plate is a monene fiber fabric carrying electrodes; the PI resin / fiber composite packaging material completely wraps the electric heating plate.

[0013] Specifically, the monene fiber fabric electric heater comprises monene fiber fabric, positive and negative electrodes respectively arranged at opposite sides of the monene fiber fabric, and lead-out electrode sheets respectively arranged at the ends of the positive and negative electrodes. The graphene fiber fabric is a fabric with a surface covered with graphene formed by growing continuous graphene sheets on glass fiber, quartz fiber, alumina fiber and other fabrics by chemical vapor deposition. Furthermore, the monene fiber fabric is a monene glass fiber fabric, and its weaving method is plain weave or twill weave; The positive and negative electrodes are continuously arranged along the two long sides of the monene fiber fabric; Further, the positive and negative electrodes are copper electrodes formed by spraying copper powder on opposite sides of the monene fiber fabric; Furthermore, the lead-out electrode sheet is a thin metal sheet welded to the ends of the positive and negative electrodes. In one embodiment of the present invention, a spot welder is used to weld a nickel sheet to the edge of a copper electrode as a lead-out electrode sheet; The PI resin in the PI resin / fiber composite packaging material is a phenylacetylene-terminated polyimide resin; The fibers in the PI resin / fiber composite packaging material are the same as or different from the fibers used to prepare the monene fiber fabric, and can be independently selected from at least one of glass fibers, quartz fibers, and alumina fibers.

[0014] The present invention also provides a method for preparing the infrared electric heating component with the heat-resistant PI resin / fiber composite package.

[0015] The method for preparing the above-mentioned heat-resistant PI resin / fiber composite encapsulated infrared electric heating component provided by the present invention comprises the following steps: 1) Positive and negative electrodes are respectively arranged on opposite sides of the monene fiber fabric, and thin metal sheets are respectively welded at the ends of the positive and negative electrodes as lead-out electrode sheets to obtain the monene fiber fabric carrying electrodes; 2) Compounding PI with fiber fabric to obtain PI / fiber fabric prepreg; 3) A layer of PI / fiber fabric prepreg is laid on the upper and lower surfaces of the electrode-carrying monene fiber fabric to form a preform, and hot pressing and curing is performed to obtain a heat-resistant PI resin / fiber composite encapsulated infrared electric heating component.

[0016] In step 1) of the above method, the graphene fiber fabric is a fabric with a surface covered with graphene formed by growing continuous graphene sheets on fabrics such as glass fiber, quartz fiber, and alumina fiber by chemical vapor deposition; Furthermore, the monene fiber fabric is a monene glass fiber fabric, and its weaving method is plain weave or twill weave; The positive and negative electrodes are continuously arranged along the two long sides of the monene fiber fabric; Furthermore, the positive and negative electrodes are copper electrodes, which are formed by spraying copper powder on opposite sides of the monene fiber fabric; The metal sheet is a nickel sheet; Further, a spot welder is used to weld nickel sheets on the edges of the positive and negative electrodes as lead-out electrode sheets; In step 2) of the above method, the mass ratio of PI to fiber is 30:70-50:50; The composite operation is as follows: firstly heat-treating the fiber to remove the surface impregnant; then impregnating the heat-treated fiber with a silane coupling agent solution to modify it; finally, coating and dispersing the crushed PI resin on the surface of the modified fiber, heat-setting, and winding.

[0017] Furthermore, the fiber is glass fiber, and the mass ratio of PI to glass fiber is 30:70; The composite operation is as follows: the glass fiber is first heat-treated: treated in a muffle furnace at 380°C for 60 minutes to remove the surface wetting agent; then modified with a coupling agent: a 3wt% ethanol solution of KH-550 silane coupling agent is prepared, the pH is adjusted to 4.5 with acetic acid, the glass fiber is impregnated with this solution for 10 minutes, and then dried at 120°C for 30 minutes; the crushed PI resin is well dispersed on the surface of the pretreated glass fiber by uniform coating, and is fixed on the surface of the glass fiber at 120°C; when winding, the curling tension gradient is controlled to decrease, the surface temperature of the winding roller is controlled at 40±2°C, and a fluorinated release film is used for interlayer isolation.

[0018] The operation of hot pressing curing molding in step 3 of the above method is: placing the preform on a platform, sequentially covering the preform with a polytetrafluoroethylene cloth, a porous film, and a stainless steel plate with air permeable holes, and then packaging it with a high-temperature glass felt, a high-temperature putty strip, and a polyimide vacuum bag; evacuating the packaged layer preform and the molding mold, and heating the mold to cure it; Wherein, the vacuum is evacuated to control the vacuum degree to (-0.096±0.002) MPa; The temperature is increased from 210° C. to 350° C. and kept at this temperature for 2 h to 14.5 h, wherein at 290° C., the pressure is increased to 1.5 MPa.

[0019] The present invention also provides an electric heating device, which contains the infrared electric heating component. Specifically, the electric heating device can be a coating and drying machine.

[0020] The present invention provides an infrared electric heating component and a preparation method thereof, in which a packaging material and a sealed material are firmly combined and integrally formed, and theoretically can realize roll-to-roll production. The packaging thickness and withstand voltage leakage performance of the infrared electric heating component can be regulated by design. The prepreg hot pressing method is used for molding, and compared with packaging methods such as gluing in other similar technical documents, the prepreg has the advantages of being airtight, resistant to high temperature aging, strong, and having a certain mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 The present invention is a flow chart of preparing an infrared electric heating component.

[0021] Figure 2 This is a diagram of the electrode preparation scheme in Example 1 of the present invention.

[0022] Figure 3 This is a top view of the PI glass fiber fabric prepreg encapsulation layered structure in Example 1 of the present invention.

[0023] Figure 4This is a side view of the PI glass fiber fabric prepreg encapsulation layered structure in Example 1 of the present invention.

[0024] Figure 5 This is a top view of the heat-resistant PI resin / fiber composite encapsulated monene glass fiber electric heating component prepared in Example 1 of the present invention.

[0025] Figure 6 This is an appearance diagram of the heat-resistant PI resin / fiber composite encapsulated monene glass fiber electric heating component prepared in Example 1 of the present invention.

[0026] Figure 7 This is an infrared thermal imaging photograph of the electric heating component prepared in Example 1 of the present invention when it reaches a steady-state temperature.

[0027] Figure 8 This is an infrared thermal imaging photograph of the electric heating component prepared in Comparative Example 1 when it reaches a steady-state temperature.

[0028] Fig. 9 This is an infrared thermal imaging photograph of the electric heating component prepared in Comparative Example 2 when it reaches a steady-state temperature. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0030] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0031] The monene fiber fabric used in the following embodiments is monene glass fiber (graphene conductive fabric), which has a square resistance of about 500Ω / sq, a length of 28cm, a width of 12cm, a thickness of 0.2mm, and a plain weave.

[0032] Electrode type and spraying method: Copper powder is continuously sprayed on the opposite sides of the monene glass fiber (plasma spray copper, width 4mm, thickness 0.12mm, nickel sheet is used as the lead, and the two are connected by spot welding process.

[0033] The polyimide resin is a phenylene vinylene terminated polyimide resin.

[0034] Example 1 The sheet resistance is 500±50Ω / sq, the thickness is 0.2mm, and the weaving method is plain monene glass fiber. Figure 2The electrode preparation scheme shown in the figure uses plasma spraying to spray copper powder on the opposite sides of the graphene conductive fabric to form a copper electrode, and then uses a spot welder to weld a nickel sheet on the edge of the copper electrode as a lead-out electrode sheet ( Figure 1 (S1).

[0035] A powdered phenylacetylene-terminated polyimide resin is used, and the mass ratio of PI resin to glass fiber is 30:70; first, the glass fiber is heat-treated: treated in a 380°C muffle furnace for 60 minutes to remove the surface impregnation agent; then a coupling agent is used for modification: a 3wt% ethanol solution of KH-550 silane coupling agent is prepared, the pH is adjusted to 4.5 with acetic acid, and the glass fiber is impregnated with this solution for 10 minutes, and then dried at 120°C for 30 minutes; the crushed PI resin is well dispersed on the pretreated glass fiber surface by uniform coating, and is fixed on the glass fiber surface at 120°C; when winding, the curling tension gradient is controlled to decrease, and the surface temperature of the winding roller is controlled at 40±2°C. A fluorinated release film is used for interlayer isolation to achieve PI and fiber fabric composite to obtain PI glass fiber fabric prepreg ( Figure 1 (S2).

[0036] According to Figure 3 and Figure 4 The packaging scheme shown in the figure lays a layer of PI glass fiber fabric prepreg on the upper and lower surfaces of the monene glass fiber fabric to form a preform. First, place the laid preform on an aluminum platform, and then cover the preform with polytetrafluoroethylene cloth, a porous membrane, and a stainless steel plate with air permeability. High-temperature glass felt, high-temperature putty strips, and polyimide vacuum bags are used for packaging. The packaged layer preform and the molding mold are evacuated, and the vacuum degree is controlled to be (-0.096±0.002) MPa. At the same time, the mold is heated from 210°C to 350°C and kept warm for 10 hours for curing. At 290°C on the way, a pressure of 1.5MPa ( Figure 1 (S3).

[0037] Finally, a heat-resistant PI resin / fiber composite encapsulated monene fiber fabric infrared electric heating component was obtained.

[0038] Comparative Example 1 In this comparative example, step S1 is the same as that in Example 1. In step S2, two polyimide films are taken, sandwiched on both sides of the monene glass fiber heating plate, and a heat-resistant adhesive (Kraft K-5800 fire-resistant high-temperature adhesive) is applied to encapsulate it.

[0039] Finally, a polyimide film-monene fiber fabric infrared electric heating component encapsulated by an adhesive is obtained.

[0040] Comparative Example 2 In this comparative example, step S1 is the same as that in Example 1. In step S2, epoxy resin is used to prepare epoxy glass fiber fabric prepreg (epoxy resin and glass fiber are compounded to form prepreg (the ratio of the two is the same as that in Example 1, the glass fiber pretreatment method is the same, and the setting agent in this preparation process is crushed solid epoxy resin, which is well dispersed on the surface of the pretreated glass fiber by uniform coating, the setting temperature is 100°C, and the winding process is basically the same). In step S3, the packaging means are the same. After the packaging is completed, the vacuum degree is controlled to be (-0.096±0.002) MPa, and the vacuum is maintained for 10 minutes before the temperature is increased, the temperature is increased to 80°C and kept for 120 minutes, and the temperature is further increased to 150°C and kept for 240 minutes for curing.

[0041] Finally, an epoxy resin / glass fiber composite encapsulated monene fiber fabric infrared electric heating component was obtained.

[0042] The structure and appearance of the heat-resistant PI resin / fiber composite encapsulated monene glass fiber electric heating component manufactured by the present invention are as follows: Figure 5 and Figure 6 shown.

[0043] The electric heating components prepared in Example 1 and Comparative Examples 1-2 were subjected to electric heating tests and withstand voltage leakage tests. The electric heating test process used an infrared thermal imager (manufacturer: American Philier, model: A615) and an AC variable frequency power supply (manufacturer: Shenzhen Toward Technology Co., Ltd., model: TAC6003), connected the electrodes of the electric heating film to the AC variable frequency power supply, set a certain constant voltage for each electric heating component, monitor the real-time temperature of the sample with an infrared thermal imager, and record the current value when the sample reaches a steady-state temperature. Figure 7 , Figure 8 and Fig. 9 Infrared thermal imaging photos of the electric heating components prepared in Example 1, Comparative Example 1 and Comparative Example 2 when reaching a steady-state temperature. A withstand voltage tester (manufacturer: Shenzhen Meiruike Electronic Technology Co., Ltd., model: RK2672AM) was used to perform the withstand voltage test.

[0044] The test results are shown in Table 1.

[0045] Table 1

[0046] After heating for about 10 seconds, the average temperatures of the electric heating components prepared in Example 1 and Comparative Examples 1-2 stabilized at 302.9°C, 303.1°C and 174.3°C, respectively. After each sample was powered on to 200°C and heated for 8 hours, no resistance attenuation was found in the samples of the examples, while the sample of Comparative Example 2 had poor heat resistance of the matrix resin, which led to oxidation of graphene, increased resistance within 8 hours, and reduced power by more than 15%. Further, through accelerated aging experiments at higher heating temperatures, it was found that the sample of Example 1 could be powered on and heated for a long time under heating conditions of 300°C (service life>10000h). The long-term reliability of the packaging method of Comparative Example 1 is not as good as that of Example 1, so its actual measured service life at 300°C does not exceed 1000h. In the voltage breakdown test, each sample showed excellent voltage resistance, and the voltage resistance of the sample of the example was higher than that of the sample of the comparative example.

[0047] From the test data, it can be seen that the infrared electric heating component of the present invention has obvious advantages in terms of maximum operating temperature, life and temperature uniformity due to the use of heat-resistant polyimide resin and reliable and firm packaging. Its maximum operating temperature can reach above 350°C, the continuous working life at around 300°C is greater than 10,000 hours, and the in-plane temperature value non-uniformity is less than 5%.

[0048] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principles of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departure from the disclosed scope in the application, and changes made with conventional techniques known in the art.

Claims

1. An infrared electric heating component, comprising a monene fiber fabric electric heating sheet and a PI resin / fiber composite packaging material laid on the upper and lower surfaces of the electric heating sheet, in, The monene fiber fabric electric heating plate is a monene fiber fabric carrying electrodes; the PI resin / fiber composite packaging material completely wraps the electric heating plate.

2. The infrared electric heating assembly according to claim 1, characterized in that: The monene fiber fabric electric heater comprises monene fiber fabric, positive and negative electrodes arranged on opposite sides of the monene fiber fabric, and lead-out electrode sheets respectively arranged at the ends of the positive and negative electrodes.

3. The infrared electric heating assembly according to claim 2, characterized in that: The graphene fiber fabric is a fabric with a surface covered with graphene formed by growing continuous graphene sheets on the fiber fabric using a chemical vapor deposition method. Wherein, the fiber fabric is selected from at least one of glass fiber, quartz fiber and alumina fiber fabric.

4. The infrared electric heating assembly according to claim 3, characterized in that: The monene fiber fabric is a monene glass fiber fabric, and its weaving method is plain or twill; the positive and negative electrodes are continuously arranged along the two long sides of the monene fiber fabric.

5. The infrared electric heating assembly according to claim 2, characterized in that: The positive and negative electrodes are copper electrodes formed by spraying copper powder on opposite sides of the monene fiber fabric; The lead-out electrode sheet is a thin metal sheet welded to the ends of the positive and negative electrodes.

6. The infrared electric heating assembly according to claim 2, characterized in that: The PI resin in the PI resin / fiber composite packaging material is a phenylacetylene-terminated polyimide resin; The fibers in the PI resin / fiber composite packaging material are the same as or different from the fibers used to prepare the monene fiber fabric, and are independently selected from at least one of glass fibers, quartz fibers, and alumina fibers.

7. A method for preparing the infrared electric heating assembly according to any one of claims 1 to 6, comprising the following steps: 1) arranging positive and negative electrodes on opposite sides of a monene fiber fabric, respectively, and welding thin metal sheets at the ends of the positive and negative electrodes as lead-out electrode sheets, respectively, to obtain a monene fiber fabric carrying electrodes; 2) Compounding PI with fiber fabric to obtain PI / fiber fabric prepreg; 3) A layer of PI / fiber fabric prepreg is laid on the upper and lower surfaces of the electrode-carrying monene fiber fabric to form a preform, and hot pressing and curing is performed to obtain a heat-resistant PI resin / fiber composite encapsulated infrared electric heating component.

8. The method according to claim 7, characterized in that In step 2), the mass ratio of PI to fiber is 30:70-50:50; The composite operation is as follows: firstly heat-treating the fiber to remove the surface impregnant; then impregnating the heat-treated fiber with a silane coupling agent solution to modify it; finally, coating and dispersing the crushed PI resin on the surface of the modified fiber, heat-setting, and winding.

9. The method according to claim 7, characterized in that: Step 3) The operation of hot pressing curing molding is as follows: placing the preform on a platform, sequentially covering the preform with polytetrafluoroethylene cloth, a porous membrane, and a stainless steel plate with air permeable holes, and then packaging it with high-temperature glass felt, high-temperature putty strips, and polyimide vacuum bags; evacuating the packaged layer preform and the molding mold, and heating the mold at the same time for curing.

10. An electric heating device, comprising the infrared electric heating component according to any one of claims 1 to 6.

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