Basf Aktiengesellschaft

Celanese Gmbh

Fiber Industries, Inc.

Gene P Daumit

Yoon S Ko

Jozef G Venner

Christopher R Slater

Chi C Young

J Eugene McAliley

Maurice M Zwick

Fredrick A Ethridge

James R Crozier, Jr

Robert Edelman

Paul E McMahon

Gerald Wayne Davis

Alan Buckley

Frederick A Ethridge

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.

Formation of melt-spun acrylic fibers which are particularly suited for

An improved multifilamentary tow of carbon fibers is provided which possesses a novel physical configuration that better enables it to undergo impregnation with a matrix-forming resin to form quality composite articles. The individual filaments of the tow are randomly decollimated and commingled with numerous filament cross-over points throughout the length of the multifilamentary tow in order to create a multitude of interstices between adjacent filaments which are well adapted to receive and retain a matrix-forming resin as evidenced by the ability of the filaments when subjected to the flaring test described herein to resist lateral expansion to a width that is as much as three times the original width. The tow commonly comprises approximately 1,000 to 50,000 filaments. Also, the filaments of the tow are substantially continuous and contain at least 70 percent carbon by weight (preferably at least 90 percent carbon by weight). In a preferred embodiment wherein the resistance to lateral expansion is the greatest, the multifilamentary bundles have been found to be capable of being readily woven with no significant productivity loss to form a quality reinforcing fabric while free of a protective size, such as that which has heretofore been required while weaving carbonaceous multifilamentary yarn bundles of the prior art.

Weaving process utilizing multifilamentary carbonaceous yarn bundles

Carbon fiber multifilamentary tow which is particularly suited for

An improved process is provided for the thermal conversion of a multifilamentary tow of an acrylic fibrous material wherein the filaments are disposed in a substantially parallel relationship in a multifilamentary tow of carbonaceous fibrous material which contains at least 70 percent (preferably at least 90 percent) carbon by weight. During at least one stage of the process the multifilamentary tow is subjected to the impingement of at least one stream of a liquid whereby the parallel relationship of the filaments is disrupted in the substantial absence of filament damage with the filaments becoming decolumnized to a degree sufficient to enable the resulting carbonaceous fibrous material to be more readily impregnated by and dispersed within a matrix-forming resin. In a preferred embodiment such impingement is carried out following a thermal stabilization step and prior to a carbonization step while the multifilamentary tow is simultaneously completely submerged within a liquid. The particularly preferred liquid for use in the process is water.

Production of a carbon fiber multifilamentary tow which is particularly

The present invention is directed to carbon fibers which are coated on the surface with a sizing agent of either a polyisocyanate, such as polymethylene polyphenyl polyisocyanate, or a sorbitol polyglycidyl ether having a specifically defined total chlorine content and epoxide equivalent weight. The coated carbon fibers are employed to prepare carbon fiber composites wherein the matrix resin is a thermoplastic polyester such as poly(1,4-butylene terephthalate). The matrix resin of the composite exhibits improved bonding with the coated carbon fibers thereby imparting improved interlaminar shear strength to the composite.

Sized carbon fibers, and thermoplastic polyester based composite

Yarns of balanced low tensile characteristics, especially low tensile factor (TE.sup.1/2) are produced in high speed spinning (e.g. greater than 10000 fpm) operations including an annealing stage by process control, particularly inverse spinning temperatures for given yarn. Polyethylene terephthalate yarns of balanced tensile characteristics and tensile factor of as little as 15-17 are prepared directly from a spin draw line at maximum productivity.

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Charlotte, NC, United States of America

Gene P Daumit