METHOD FOR PREPARING ELECTROTHERMAL HEATING SHEET FROM CARBON FIBER BRAIDED FABRIC SCRAPS

Abstract

Provided is a method for preparing an electrothermal heating sheet from carbon fiber braided fabric scraps, including: cutting clumps of disordered carbon fiber braided fabric scraps into chopped carbon fibers; washing the chopped carbon fibers by separately using acetone and deionized water, and drying; preparing a corresponding dispersion; adding the chopped carbon fibers to the dispersion, and fully dispersing; performing vacuum filtration by using a double-layer metal screen, and drying to obtain a chopped carbon fiber felt; cutting the chopped carbon fiber felt, sticking electrodes to two ends of the chopped carbon fiber felt, and covering thermoplastic polyurethane (TPU) sheets on front and back surfaces of the chopped carbon fiber felt to form a heating sheet product having electrothermal performance and electromagnetic shielding performance. The direct discarding of the carbon fiber braided fabric scraps and the scraps resulting from cutting in the preparation process as wastes may result in not only great wasting of materials but also in environmental pollution. The method fully utilizes the carbon fiber braided fabric scraps and is low in cost, and the prepared product has excellent electrothermal performance and electromagnetic shielding performance.

Claims

1. A method for preparing a carbon fiber felt from carbon fiber braided fabric scraps and sticking electrodes, comprising the following steps: step 1) trimming: cutting clumps of disordered carbon fiber braided fabric scraps with a cutting length controlled to be 5 mm to 10 mm to obtain chopped carbon fibers; step 2) standing: adding the chopped carbon fibers into a beaker containing acetone, and standing the chopped carbon fibers in a ventilation environment for 10 h to 14 h; step 3) washing and drying: repeatedly washing the chopped carbon fibers after the standing by separately using acetone and deionized water, and drying in a drying oven to obtain dried chopped carbon fibers; step 4) preparation of a dispersion: adding deionized water and absolute ethyl alcohol into two containers, respectively; dispersing a sodium carboxymethyl cellulose powder in the absolute ethyl alcohol, wherein a ratio of the sodium carboxymethyl cellulose powder to the absolute ethyl alcohol is in a range of 1 g:10-13 mL, and a volume ratio of the deionized water to the absolute ethyl alcohol is in a range of 8:1 to 10:1; and fully mixing the absolute ethyl alcohol dispersed with the sodium carboxymethyl cellulose powder with the deionized water to form the dispersion; step 5) preparation of a chopped carbon fiber dispersion: adding 1 g to 2 g of the dried chopped carbon fibers obtained in step 3) into the dispersion and fully stirring to make the dried chopped carbon fibers be fully dispersed in the dispersion to form the chopped carbon fiber dispersion; step 6) formation of a chopped carbon fiber felt sheet: guiding the chopped carbon fiber dispersion into a Buchner funnel with a double-layer metal screen, fully stirring and standing for 10 min, and turning on a vacuum filtration device and performing vacuum filtration to obtain the chopped carbon fiber felt sheet, wherein a gram weight of the chopped carbon fiber felt sheet is in a range of 10 g/m.sup.2 and 80 g/m.sup.2; step 7) drying: taking down an upper metal screen with the chopped carbon fiber felt sheet, and drying in a drying oven to obtain a circular chopped carbon fiber felt, and cutting the circular chopped carbon fiber felt to obtain a cut chopped carbon fiber felt; and step 8) making of electrodes: sticking electrodes to two ends of the cut chopped carbon fiber felt by uniformly coating a silver conductive adhesive onto the electrodes and sticking to the two ends of the cut chopped carbon fiber felt, and then drying a resulting chopped carbon fiber felt in a drying oven to obtain a carbon fiber felt sheet with the electrodes.

2. A method for preparing an electrothermal heating sheet from carbon fiber braided fabric scraps, comprising the following steps: step 1) trimming: cutting clumps of disordered carbon fiber braided fabric scraps with a cutting length controlled to be 5 mm to 10 mm to obtain chopped carbon fibers; step 2) standing: adding the chopped carbon fibers into a beaker containing acetone and standing the chopped carbon fibers in a ventilation environment for 10 h to 14 h; step 3) washing and drying: repeatedly washing the chopped carbon fibers after the standing by separately using acetone and deionized water, and drying in a drying oven to obtain dried chopped carbon fibers; step 4) preparation of a dispersion: adding deionized water and absolute ethyl alcohol into two containers, respectively; dispersing a sodium carboxymethyl cellulose powder in the absolute ethyl alcohol, wherein a ratio of the sodium carboxymethyl cellulose powder to the absolute ethyl alcohol is in a range of 1 g:10-13 mL, and a volume ratio of the deionized water to the absolute ethyl alcohol is in a range of 8:1 to 10:1; and fully mixing the absolute ethyl alcohol dispersed with the sodium carboxymethyl cellulose powder with the deionized water to form the dispersion; step 5) preparation of a chopped carbon fiber dispersion: adding 1 g to 2 g of the dried chopped carbon fibers obtained in step 3) into the dispersion and fully stirring to make the dried chopped carbon fibers be fully dispersed in the dispersion to form the chopped carbon fiber dispersion; step 6) formation of a chopped carbon fiber felt sheet: guiding the chopped carbon fiber dispersion into a Buchner funnel with a double-layer metal screen, fully stirring and standing for 10 min, and turning on a vacuum filtration device and performing vacuum filtration to obtain the chopped carbon fiber felt sheet, wherein a gram weight of the chopped carbon fiber felt sheet is in a range of 10 g/m.sup.2 and 80 g/m.sup.2; step 7) drying: taking down an upper metal screen with the chopped carbon fiber felt sheet, and drying in a drying oven to obtain a circular chopped carbon fiber felt, and cutting the circular chopped carbon fiber felt to obtain a cut chopped carbon fiber felt; step 8) making of electrodes: sticking electrodes to two ends of the cut chopped carbon fiber felt by uniformly coating a silver conductive adhesive onto the electrodes and sticking to the two ends of the chopped carbon fiber felt, and then drying a resulting chopped carbon fiber felt in a drying oven to obtain a carbon fiber felt sheet with the electrodes; step 9) preparation of a thermoplastic polyurethane (TPU) sheet: drying TPU particles in a drying oven to remove moisture to obtain dried TPU particles, and then preparing the dried TPU particles into a TPU sheet by using a vacuum laminator, wherein a thickness of the TPU sheet is controlled to be 0.1 mm to 2 mm; and step 10) forming of a product: sandwiching one layer of the chopped carbon fiber felt with the electrodes between two layers of the TPU sheet, and subjecting a resulting system to plastic packaging by a vacuum laminator to obtain the electrothermal heating sheet.

3. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 2, wherein in step 3), the drying in the drying oven is performed at a temperature of 60 C. for 1 h.

4. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 3, wherein in step 4), the deionized water is in an amount of 420 mL to 460 mL, the absolute ethyl alcohol is in an amount of 42 mL to 50 mL, and the sodium carboxymethyl cellulose powder is in an amount of 3 g to 5 g; and the mixing is performed under mechanical stirring at a rotation speed of 300 rpm for 3 h to dissolve sodium carboxymethyl cellulose, the deionized water, and the absolute ethyl alcohol to obtain the dispersion in which the sodium carboxymethyl cellulose is fully dissolved.

5. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 3, wherein in step 5), the chopped carbon fibers are added into the dispersion and stirred with a mechanical stirring device at a rotation speed of 300 rpm for 1 h.

6. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 5, wherein in step 7), the drying in the drying oven is performed at a temperature of 60 C. for 3 h; the circular chopped carbon fiber felt has a diameter of 90 mm; and the circular chopped carbon fiber felt is cut to obtain a felt sheet.

7. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 6, wherein in step 7), the felt sheet has a size of 50 mm50 mm.

8. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 6, wherein in step 8), the electrode is a red copper electrode; and the drying in the drying oven is performed at a temperature of 60 C. for 30 min.

9. The method for preparing the electrothermal heating sheet from the carbon fiber braided fabric scraps of claim 8, wherein in step 9), the moisture is removed from the TPU particles at a temperature of 60 C. for 10 h; and the vacuum laminator is at a temperature of 210 C. and under a pressure of 4 MPa.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 shows a flowchart of a method for preparing an electrothermal heating sheet from carbon fiber braided fabric scraps according to an embodiment of the present disclosure;

[0041] FIG. 2 shows a diagram illustrating a comparison of samples of carbon fiber braided fabric scraps in cutting, soaking, drying, and sheet forming processes according to an embodiment of the present disclosure;

[0042] FIG. 3 shows a structural schematic diagram of an electrothermal heating sheet according to an embodiment of the present disclosure;

[0043] FIG. 4 shows a schematic diagram of an electromagnetic shielding efficiency of an electrothermal heating sheet according to an embodiment of the present disclosure;

[0044] FIG. 5 shows a diagram of a heat profile of an electrothermal heating sheet according to an embodiment of the present disclosure; and

[0045] FIG. 6 shows a curve diagram of temperatures as a function of time under different voltages of an electrothermal heating sheet according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] As shown in FIG. 1, a method for preparing an electrothermal heating sheet from carbon fiber braided fabric scraps includes the following steps. [0047] Step 1) trimming: clumps of disordered carbon fiber braided fabric scraps are cut with a cutting length controlled to be 5 mm to 10 mm to form chopped carbon fibers. This mainly has two purposes: the first one is to facilitate the subsequent dispersion process of the carbon fibers, avoiding the problem that the clumps of carbon fibers cannot be treated; and the second one is to improve the electromagnetic shielding performance of the carbon fibers. The chopped carbon fibers have excellent electromagnetic shielding performance when the length thereof is within a reasonable range. In FIG. 2, the upper left image shows the clumps of disordered carbon fiber braided fabric scraps. [0048] Step 2) standing: the chopped carbon fibers are added into a beaker containing acetone and stood in a ventilation environment for 10 h to 14 h, in a state as shown in the upper right image in FIG. 2. [0049] Step 3) washing and drying: the chopped carbon fibers after the standing are washed repeatedly by separately using acetone and deionized water, and dried in a drying oven at a temperature of 60 C. for 1 h. This step is mainly to wash off a pulp on the surface of the carbon fibers. [0050] Step 4) preparation of a dispersion: deionized water and absolute ethyl alcohol are added into two containers, respectively, and then a sodium carboxymethyl cellulose powder is dispersed in the absolute ethyl alcohol. Where, a volume ratio of the deionized water to the absolute ethyl alcohol is in a range of 8:1 to 10:1, and a ratio of the sodium carboxymethyl cellulose powder to the absolute ethyl alcohol is in a range of 1 g:10-13 mL. The ratio is controlled in the above range, which could prevent flocculation and not easy dissolution of the sodium carboxymethyl cellulose when added to the deionized water. Specifically, the deionized water is in an amount of 420 mL to 460 mL, the absolute ethyl alcohol is in an amount of 42 mL to 50 mL, and the sodium carboxymethyl cellulose powder is in an amount of 3 g to 5 g. The absolute ethyl alcohol dispersed with the sodium carboxymethyl cellulose is fully mixed with the deionized water, and dissolved by mechanical stirring at a rotation speed of 300 rpm for 3 h, to obtain the dispersion in which the sodium carboxymethyl cellulose is fully dissolved. [0051] Step 5) preparation of a chopped carbon fiber dispersion: 1 g to 2 g of the chopped carbon fibers is added into the dispersion and fully stirred by using a mechanical stirring device at a rotation speed of 300 rpm for 1 h to make the chopped carbon fibers be fully dispersed in the dispersion to form the chopped carbon fiber dispersion, as shown in the left lower image in FIG. 2. [0052] Step 6) formation of a chopped carbon fiber felt sheet: the chopped carbon fiber dispersion is guided into a Buchner funnel with a double-layer metal screen, fully stirred, and stood for 10 min. Then, a vacuum filtration device is turned on and vacuum filtration is performed to obtain the chopped carbon fiber felt sheet, where a gram weight of chopped carbon fiber felt sheet is in a range of 10 g/m.sup.2 and 80 g/m.sup.2, as shown in the right lower image in FIG. 2. [0053] Step 7) drying: an upper metal screen with the chopped carbon fiber felt sheet is taken down and dried in a drying oven at a temperature of 60 C. for 3 h to obtain a circular chopped carbon fiber felt with a diameter of 90 mm, and the circular chopped carbon fiber felt is cut to obtain a cut chopped carbon fiber felt with a size of 50 mm50 mm. [0054] step 8) making of electrodes: red copper electrodes are used and stuck on two ends of the cut chopped carbon fiber felt by uniformly coating a silver conductive adhesive onto the electrodes and sticking to the two ends of the chopped carbon fiber felt, and then putting a resulting chopped carbon fiber felt in a drying oven for drying, where the electrode has a size of 80 mm5 mm0.02 mm. The silver conductive adhesive is uniformly coated onto the electrodes, and the electrodes are stuck on the two ends of the chopped carbon fiber felt, and a resulting chopped carbon fiber felt is put in a drying oven at 60 C. for 30 min such that the silver conductive adhesive is fully dried, thereby guaranteeing that the electrodes are bonded to the chopped carbon fiber felt more firmly. [0055] Step 9) preparation of a TPU sheet: TPU (thermoplastic polyurethane, 1185A, polyether type) particles are put into a drying oven at 60 C. for 10 h to completely remove moisture in the TPU to obtain dried TPU particles a thickness controlled to be 0.1 mm to 2 mm. The dried TPU particles are prepared into a TPU sheet with a size of 60 mm60 mm0.5 mm by using a vacuum laminator at a temperature of 210 C. and under a pressure of 4 MPa for later use. [0056] Step 10) forming of a product: one layer of the chopped carbon fiber felt with the electrodes is sandwiched between two layers of the TPU sheets, and a resulting system is plastic packaged by a vacuum laminator to obtain a product, as shown in FIG. 3, where 1 represents the electrode, 2 represents the chopped carbon fiber felt, and 3 represents the TPU sheet.

[0057] As shown in FIG. 4, a data diagram of an electromagnetic shielding efficiency experiment conducted on the product is illustrated.

[0058] As shown in FIG. 5, a diagram of heat profiles of the product which is electrified and heated under 3 V, 4 V, 5 V, and 6 V is illustrated.

[0059] As shown in FIG. 6, a curve diagram of temperatures as a function of time when the product is electrified and heated under 3 V, 4 V, 5 V, and 6 V is illustrated.

[0060] The above described are merely preferred embodiments of the present disclosure rather than limitations to the present disclosure in any form. It should be noted that those skilled in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should be deemed as falling within the scope of the present disclosure.