US Patent No. 10,190,243

METHOD OF PREPARING OF NATURAL GRAPHENE CELLULOSE BLENDED MELTBLOWN NONWOVEN FABRIC


Patent No. 10,190,243
Issue Date January 29, 2019
Title Method Of Preparing Of Natural Graphene Cellulose Blended Meltblown Nonwoven Fabric
Inventorship Wen-Tung Chou, Changhua County (TW)
Ming-Yi Lai, Changhua County (TW)
Kun-Shan Huang, Tainan (TW)
Shao-Hua Chou, Taichung (TW)
Chia-Yu Hsu, Taichung (TW)
Assignee ACELON CHEMICALS AND FIBER CORPORATION, Changhua County (TW)

Claim of US Patent No. 10,190,243

1. A method of preparing natural graphene cellulose blended meltblown nonwoven fabric, which comprises the following steps:(a) combining a graphite powder with a solution comprising 1 to 10 wt. % of a first compound selected from the group consisting of sulfuric acid (H2SO4), hydrochloric acid (HCl), perchloric acid (HClO4), hydrogen iodide (HI), hydrofluoric acid (HF), and nitric acid (HNO3), then stirring for 30 minutes in an ice bath environment;
(b) adding a solution comprising 1 to 20 wt. % potassium permanganate (KMnO4) to the product of step (a), stirring for 1 to 2 hours, and adding distilled water, wherein the potassium permanganate solution is continuously added until reaction of the potassium permanganate and the product of step (a) and the distilled water is complete;
(c) adding a solution comprising 1 to 10 wt. % hydrogen peroxide (H2O2) to the product of step (b), wherein the hydrogen peroxide solution is added until reaction between the hydrogen peroxide and the product step (b) is complete and the mixture becomes green, then filtering the green solution into a cake;
(d) rinsing the cake of step (c) with a solution comprising 5 wt. % hydrochloric acid (HCl) to remove sulfate ions, then washing the cake with distilled water;
(e) drying the cake of step (d) in an oven at 40° C. for 2 hrs to obtain a dried solid graphite oxide;
(f) adding distilled water to the dried solid graphite oxide of step (e), wherein the distilled water is added up to 200 mls per 0.06 to 1.0 g of the dried solid graphite oxide, then treating by ultrasonic vibration for 30 minutes to obtain a graphite oxide solution having a graphite oxide concentration of 0.03 wt. % to 0.5 wt. %;
(g) adding a solution comprising 1 to 10 wt. % of a second compound selected from the group consisting of sodium borohydride (NaBH4), potassium borohydride (KBH4), lithium aluminum hydride (LiAlH4), and sodium citrate (C6H5Na3O7) to the graphite oxide solution of step (f), then treating by ultrasonic vibration for 30 to 60 minutes, wherein in the resulting solution, the ratio of graphene oxide to the second compound is 1:1 to 1:5 by weight;
(h) filtrating the product of step (g), washing the filtrate with water 3 to 5 times to remove the second compound, then back-filtrating to obtain a graphene solution;
(i) adding the graphene solution of step (h) to a slurry solution formed by mixing a pulp with N-methylmorpholine N-oxide (NMMO) and a stabilizer in an expansion dissolving tank, then mixing at 60 to 80° C., wherein the graphene solution of step (h) is added in a ratio of 0.11 to 5.0 wt. %, the pulp is selected from the group consisting of wood pulp, cotton pulp, bamboo pulp and a mixture of cotton and bamboo pulp, the pulp comprises ?-cellulose in an amount of 65% or more with a polymerization degree of 500 to 1500; and the NMMO has a concentration of 50% to 78%;
(j) removing water from the product of step (i) using a Thin Film Evaporator (TFE) and heating at 80 to 130° C., wherein the water is removed to 5% to 13% within 5 minutes and the cellulose is dissolved to form a spinning dope, and the amount ratio of each component among the components comprised in the dope is: water (H2O) 5% to 15%, N-methylmorpholine N-oxide (NMMO) 70% to 90%, and cellulose 5% to 15%;
(k) squeezing the spinning dope of step (j) from a spinning orifice using a meltblown process to form a natural graphene cellulose blended filament strand and piling into a fibrous network structure on a collector, which comprises pressuring the spinning dope by a metering pump, filtrating and degassing by a continuous filter (CPF), transporting the spinning dope into a spinning tank, continuously blowing hot air into the spinning orifice and outputting an air stream from the area surrounding the spinning orifice, forcing the spinning dope to be molten and squeezed to the outside of the spinning orifice to form a uniform natural graphene cellulose blended filament strand, and piling the filament strand onto a fibrous network structure on a collector; and
(l) spraying a water mist to force the natural graphene cellulose blended filament strand of step (k) into a coagulation liquid, solidifying, regenerating and washing the filament strand, and water needle punching, drying, oiling and coiling the filament strand to form a natural graphene cellulose blended meltblown nonwoven fabric, wherein the concentration of the coagulation liquid is between 2.0% to 10.0%, and after washing, the amount of residual NMMO solvent is less than 0.1%.