Process for the production of carbon filaments

Claim 2

IN A PROCESS FOR THE PRODUCTION OF A CARBON FILAMENT FROM A DRY SPUN ACRYLIC FILAMENT SELECTED FROM THE GROUP CONSISTING ESSENTIALLY OF AN ACRYLONITRILE HOMOPOLYMER AND AN ACRYLONITRILE COPOLYMER WHICH CONTAINS AT LEAST ABOUT 85 MOL PERCENT ACRYLONITRILE UNITS AND UP TO ABOUT 15 MOL PERCENT OF ONE OR MORE COPOLYMERIZED MONOVINYL UNITS WHICH IS CAPABLE OF ABSORBING WATER, COMPRISING THERMALLY STABILIZING SAID FILAMENT UNTIL NON-BURNING WHEN SUBJECTED TO AN ORDINARY MATCH FLAME, AND HEATING SAID STABLIZED FILAMENT IN A NON-OXIDIZING ATMOSPHERE AT A TEMPERATURE OF AT LEAST ABOUT 1000*C. UNTIL A CARBONACEOUS FILAMENT IS FORMED WHICH CONTAINS AT LEAST ABOUT 90 PERCENT CARBON BY WEIGHT; THE IMPROVEMENT COMPRISING CONTACTING SAID DRY SPUM ACRYLIC FILAMENT PRIOR TO SAID THERMAL STABILIZATION WITH WATER AT A TEMPERATURE OF ABOUT 20*C TO 90*C. UNTIL SAID FILAMENT SUBSTANTIALLY BECOMES WATER-LADEN, AND DRAWING THE RESULTING WATER-LADEN ACRYLIC FILAMENT WHILE SUSPENDED IN A HEATED GASEOUS ATMOSPHERE AT A TEMPERATURE OF AT LEAST 100*C. TO FORM AN ACRYLIC FILAMENT HAVING A HIGHLY MICROPOROUS AND FIBRILLAR INTERNAL STRUCTURE WHICH IS PARTICULARLY SUITED FOR THERMAL CONVERSION TO A CARBON FILAMENT.

Claim 3

An improved process according to claim 1 wherein said acrylic filament is an acrylonitrile homopolymer.

Claim 4

An improved process according to claim 1 wherein said water is provided at a temperature of about 40* to 60*C. when contacted with said dry spun acrylic filament.

Claim 5

An improved process according to claim 1 wherein said drawing of said water-laden filament is conducted in a heated gaseous atmosphere at a temperature of about 100* to 180*C.

Claim 6

An improved process according to claim 4 wherein said heated gaseous atmosphere is saturated steam.

Claim 7

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until non-burning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising contacting said dry spun acrylic filament containing 5 to 30 percent by weight of water-miscible solvent prior to said thermal stabilization with water at a temperature of about 20* to 90*C. until residual solvent present therein is substantially removed and water is provided within micropores present therein, and drawing the resulting water-laden acrylic filament while suspended in a heated gaseous atmosphere at a temperature of at least 100*C. wherein the micropores present therein are substantially elongated and an acrylic filament is formed having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 8

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until non-burning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising contacting said dry spun acrylic filament containing 5 to 30 percent by weight of water-miscible solvent prior to said thermal stabilization with water at a temperature of about 20* to 90*C. until residual solvent present therein is substantially removed and water is provided within micropores present therein, and drawing the resulting water-laden acrylic filament while suspended in a heated gaseous atmosphere at a temperature of at least 100*C. wherein the micropores present therein are substantially elongated and an acrylic filament is formed having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 9

An improved process according to claim 6 wherein said acrylic filament is an acrylonitrile homopolymer.

Claim 10

An improved process according to claim 6 wherein said water-miscible solvent is selected from the group consisting essentially of N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and N-methyl-2-pyrrolidone.

Claim 11

An improved process according to claim 6 wherein said drawing of said water-laden acrylic filament is conducted in a heated gaseous atmosphere at a temperature of about 100* to 180*C.

Claim 12

An improved process according to claim 9 wherein said heated gaseous atmosphere is saturated steam.

Claim 13

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until nonburning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising: a. providing a spinning solution having a low shear viscosity of about 100 to 1000 poise measured at 100*C. comprising (1) said acrylic polymer in a concentration of about 20 to 30 percent by weight based upon the total weight of the solution, and (2) a solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and N-methyl-2-pyrrolidone, b. extruding said solution of said acrylic polymer into a spinning zone containing an evaporative atmosphere to form a dry spun acrylic filament containing about 5 to 30 percent solvent by weight, c. continuously passing said dry spun acrylic filament from said spinning zone to a first drawing zone containing a saturated steam atmosphere provided at about 100* to 120*C., d. drawing said dry spun acrylic filament containing about 5 to 30 percent solvent by weight at a draw ratio of about 1.5:1 to 6:1 while passing through said first drawing zone to form an acrylic filament containing a microporous internal structure, e. contacting said resulting acrylic filament containing a microporous internal structure with water maintained at about 20* to 90*C. wherein the residual solvent present therein is substantially removed and replaced by water, and f. drawing the resulting water-laden acrylic filament containing a microporous internal structure at a draw ratio of about 2:1 to 8:1 while passing through a second drawing zone containing steam provided at about 100* to 180*C. wherein the micropores present therein are substantially elongated to form an acrylic filament having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 14

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until nonburning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising: a. providing a spinning solution having a low shear viscosity of about 100 to 1000 poise measured at 100*C. comprising (1) said acrylic polymer in a concentration of about 20 to 30 percent by weight based upon the total weight of the solution, and (2) a solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and N-methyl-2-pyrrolidone, b. extruding said solution of said acrylic polymer into a spinning zone containing an evaporative atmosphere to form a dry spun acrylic filament containing about 5 to 30 percent solvent by weight, c. continuously passing said dry spun acrylic filament from said spinning zone to a first drawing zone containing a saturated steam atmosphere provided at about 100* to 120*C., d. drawing said dry spun acrylic filament containing about 5 to 30 percent solvent by weight at a draw ratio of about 1.5:1 to 6:1 while passing through said first drawing zone to form an acrylic filament containing a microporous internal structure, e. contacting said resulting acrylic filament containing a microporous internal structure with water maintained at about 20* to 90*C. wherein the residual solvent present therein is substantially removed and replaced by water, and f. drawing the resulting water-laden acrylic filament containing a microporous internal structure at a draw ratio of about 2:1 to 8:1 while passing through a second drawing zone containing steam provided at about 100* to 180*C. wherein the micropores present therein are substantially elongated to form an acrylic filament having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 15

An improved process according to claim 11 wherein said acrylic filament is an acrylonitrile homopolymer.

Claim 16

An improved process according to claim 11 wherein said solvent is N,N-dimethylformamide.

Claim 17

An improved process according to claim 11 wherein said spinning solution contains said acrylic polymer in a concentration of about 24 to 27 percent by weight based upon the total weight of the solution.

Claim 18

An improved process according to claim 11 wherein said first drawing zone and said second drawing zone contain saturated steam having a temperature of about 100*C.

Claim 19

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until non-burning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising: a. providing a spinning solution having a low shear viscosity of about 200 to 500 poise measured at 100*C. comprising (1) said acrylic polymer in a concentration of about 24 to 27 percent by weight based upon the total weight of the solution, and (2) a N,N-dimethylformamide solvent, b. extruding said solution of said acrylic polymer into a spinning zone containing an evaporative atmosphere to form a continuous length of dry spun acrylic filament containing about 5 to 30 percent N,N-dimethylformamide by weight, c. continuously passing said dry spun acrylic filament from said spinning zone to a first drawing zone containing a saturated steam atmosphere provided at about 100*C., d. drawing said dry spun acrylic filament containing about 5 to 30 percent N,N-dimethylformamide by weight at a draw ratio of about 2:1 to 3.5:1 while passing through a first drawing zone to form an acrylic filament containing a microporous internal structure, e. contacting said resulting continuous length of acrylic filament containing a microporous internal structure with water maintained at about 40* to 60*C. wherein the residual N,N-dimethylformamide present therein is substantially removed and replaced by water, and f. drawing the resulting water-laden acrylic filament containing a microporous internal structure at a draw ratio of about 2:1 to 3:1 while passing through a second drawing zone containing saturated steam provided at about 100*C. wherein the micropores present therein are substantially elongated to form an acrylic filament having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 20

In a process for the production of a carbon filament from a dry spun acrylic filament selected from the group consisting essentially of an acrylonitrile homopolymer and an acrylonitrile copolymer which contains at least about 85 mol percent acrylonitrile units and up to about 15 mol percent of one or more copolymerized monovinyl units which is capable of absorbing water, comprising thermally stabilizing said filament until non-burning when subjected to an ordinary match flame, and heating said stabilized filament in an inert atmosphere at a temperature of at least about 1000*C. until a carbonaceous filament is formed which contains at least about 90 percent carbon by weight; the improvement comprising: a. providing a spinning solution having a low shear viscosity of about 200 to 500 poise measured at 100*C. comprising (1) said acrylic polymer in a concentration of about 24 to 27 percent by weight based upon the total weight of the solution, and (2) a N,N-dimethylformamide solvent, b. extruding said solution of said acrylic polymer into a spinning zone containing an evaporative atmosphere to form a continuous length of dry spun acrylic filament containing about 5 to 30 percent N,N-dimethylformamide by weight, c. continuously passing said dry spun acrylic filament from said spinning zone to a first drawing zone containing a saturated steam atmosphere provided at about 100*C., d. drawing said dry spun acrylic filament containing about 5 to 30 percent N,N-dimethylformamide by weight at a draw ratio of about 2:1 to 3.5:1 while passing through a first drawing zone to form an acrylic filament containing a microporous internal structure, e. contacting said resulting continuous length of acrylic filament containing a microporous internal structure with water maintained at about 40* to 60*C. wherein the residual N,N-dimethylformamide present therein is substantially removed and replaced by water, and f. drawing the resulting water-laden acrylic filament containing a microporous internal structure at a draw ratio of about 2:1 to 3:1 while passing through a second drawing zone containing saturated steam provided at about 100*C. wherein the micropores present therein are substantially elongated to form an acrylic filament having a highly microporous and fibrillar internal structure which is particularly suited for thermal conversion to a carbon filament.

Claim 21

An improved process according to claim 16 wherein said acrylic filament is an acrylonitrile homopolymer.

Claim 22

An improved process according to claim 16 wherein said spinning solution contains said acrylic polymer in a concentration of about 25 percent by weight based upon the total weight of the solution.

Claim 23

An improved process according to claim 16 wherein said evaporative atmosphere into which said solution is extruded is nitrogen.

Claim 24

An improved process according to claim 16 wherein said dry spun acrylic filament when initially introduced into said first drawing zone contains N,N-dimethylformamide in a concentration of about 8 to 10 percent by weight.