Basf Aktiengesellschaft

Chi C Young

Gene P Daumit

Jozef G Venner

Yoon S Ko

Christopher R Slater

Maurice M Zwick

An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, acrylic fiber precursors possessing a wide varity of cross-sectional configurations and a highly uniform internal structure now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration which are substantially void free when examined in cross secton at a magnification of 2,000.times..

Melt-spun acrylic fibers possessing a highly uniform internal structure

An acrylic multifilamentary material possessing an internal structure which is well suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of C.sub.1 to C.sub.2 nitroalkane and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. During the melt extrusion a C.sub.1 to C.sub.4 monohydroxy alkanol preferably also is present in the substantially homogenous admixture. The fibrous material which is capable of readily undergoing drawing next is passed through a heat treatment zone wherein the evolution of residual nitroalkane, monohydroxy alkanol and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fiberous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, acrylic fiber precursors possessing a wide variety of cross-sectional configurations now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration.

Formation of melt-spun acrylic fibers which are well suited for thermal

An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile, C.sub.1 to C.sub.4 monohydroxy alkanol, and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile, the monohydroxy alkanol and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, acrylic fiber precursors possessing a wide variety of cross-sectional configurations now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration.

Melt-spun acrylic fibers which are particularly suited for thermal

An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, acrylic fiber precursors possessing a wide variety of cross-sectional configurations and a highly uniform internal structure now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration which are substantially void free when examined in cross section at a magnification of 2,000X.

Formation of melt-spun acrylic fibers possessing a highly uniform

An acrylic multifilamentary material possessing an internal structure which is well suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of C.sub.1 to C.sub.2 nitroalkane and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. During the melt extrusion a C.sub.1 to C.sub.4 monohydroxy alkanol preferably also is present in the substantially homogenous admixture. The fibrous material which is capable of readily undergoing drawing next is passed through a heat treatment zone wherein the evolution of residual nitroalkane, monohydroxy alkanol and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, acrylic fiber precursors possessing a wide variety of cross-sectional configurations now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration.

An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile, C.sub.1 to C.sub.4 monohydroxy alkanol, and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile, the monohydroxy alkanol and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production. One accordingly is provided a reliable route to form a fibrous acrylic precursor for carbon fiber production without the necessity to employ the solution-spinning routes commonly utilized in the prior art for precursor formation. One can now eliminate the utilization and handling of large amounts of solvent as has heretofore been necessary when forming an acrylic carbon fiber precursor. Also, arcylic fiber precursors possessing a wide variety of cross-sectional configurations now are made possible which can be thermally converted into carbon fibers of a similar cross-sectional configuration.

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Charlotte, NC, United States of America

Chi C Young