A process for the production of acrylic fibers, in particular a spinning process for obtaining precursor fibers of carbon fiber by the wet spinning of a polymer solution in an organic solvent and the relative apparatus.

The present disclosure relates generally to carbon fibers having high tensile strength and modulus of elasticity, as well as a process for the manufacture of such carbon fiber. The process comprises spinning a polymer/solvent solution into a solvent/water bath in the range of 78%-85% solvent, thereby producing a dense fiber structure, and subsequently carbonizing the polymer precursor fiber at a lower than typical carbonization temperature to form carbon fibers.

A metal adsorption acrylic fiber wherein the strontium adsorption rate is 85% or more when the strontium adsorption rate is measured using the following measurement method. A strontium adsorption rate measurement method (strontium 0.1 ppm measurement method) involves immersing a metal adsorption acrylic fiber into an immersion fluid, collecting the immersion fluid as a testing solution 24 hours after beginning the immersion, analyzing the quantity of strontium in the testing solution, obtaining the concentration (C.sub.1) (ppm) of strontium in the testing solution, creating a contrast solution, analyzing the quantity of strontium in the contrast solution as in the case with the testing solution, obtaining the concentration (C.sub.2) (ppm) of strontium in the contrast solution, and calculating the strontium adsorption rate of the metal adsorption acrylic fiber by using the following equation: strontium adsorption rate (%)={(C.sub.2−C.sub.1)/C.sub.2}×100.

A metal adsorption acrylic fiber wherein the strontium adsorption rate is 85% or more when the strontium adsorption rate is measured using the following measurement method. A strontium adsorption rate measurement method (strontium 0.1 ppm measurement method) involves immersing a metal adsorption acrylic fiber into an immersion fluid, collecting the immersion fluid as a testing solution 24 hours after beginning the immersion, analyzing the quantity of strontium in the testing solution, obtaining the concentration (C.sub.1) (ppm) of strontium in the testing solution, creating a contrast solution, analyzing the quantity of strontium in the contrast solution as in the case with the testing solution, obtaining the concentration (C.sub.2) (ppm) of strontium in the contrast solution, and calculating the strontium adsorption rate of the metal adsorption acrylic fiber by using the following equation: strontium adsorption rate (%)={(C.sub.2−C.sub.1)/C.sub.2}×100.

The invention relates to a method for the production of thermally stabilised melt spun fibres, in which polyacrylonitrile (PAN) fibres or PAN fibre precursors produced by melt spinning are treated in an aqueous alkaline solution which comprises in addition a solvent for PAN. Likewise, the invention relates to fibres which are producible according to this method.

The invention relates to melt spinnable copolymers of polyacrylonitrile (PAN) which are producible by means of copolymerisation of acrylonitrile with an alkoxyalkylacrylate. As additional comonomers alkylacrylates and vinyl esters may be considered. Likewise, the invention relates to a method for the production of fibres or fibre precursors, in particular carbon fibre precursors, by means of melt spinning, in which the mentioned copolymer is used. Furthermore, the invention relates to fibres produced in this way, in particular carbon fibres.

The invention relates to melt spinnable copolymers of polyacrylonitrile (PAN) which are producible by means of copolymerisation of acrylonitrile with an alkoxyalkylacrylate. As additional comonomers alkylacrylates and vinyl esters may be considered. Likewise, the invention relates to a method for the production of fibres or fibre precursors, in particular carbon fibre precursors, by means of melt spinning, in which the mentioned copolymer is used. Furthermore, the invention relates to fibres produced in this way, in particular carbon fibres.

The invention relates to a method for thermally stabilizing melt-spun PAN precursors. For this purpose, the invention provides a continuous method for producing a thermally stabilized multifilament thread made of a meltable copolymer of polyacrylonitrile (PAN), wherein a pre-stabilized multifilament thread is thermally stabilized and in the process at least temporarily stretched. The invention additionally relates to a thermally stabilized multifilament thread which can be obtained according to a corresponding method and to a carbon fiber which is made of the correspondingly thermally stabilized multifilament thread.

The invention relates to a method for thermally stabilizing melt-spun PAN precursors. For this purpose, the invention provides a continuous method for producing a thermally stabilized multifilament thread made of a meltable copolymer of polyacrylonitrile (PAN), wherein a pre-stabilized multifilament thread is thermally stabilized and in the process at least temporarily stretched. The invention additionally relates to a thermally stabilized multifilament thread which can be obtained according to a corresponding method and to a carbon fiber which is made of the correspondingly thermally stabilized multifilament thread.

The present invention provides: an acrylic fiber having a fineness of 0.5 to 3.5 dtex and having excellent gloss, pilling resistance, and texture; a method for producing said acrylic fiber; and a spun yarn and a knitted fabric containing said acrylic fiber. Provided is an acrylic fiber having a filament fineness of 0.5 to 3.5 dtex, wherein the product K of the value of knot strength (cN/dtex) and the value of knot elongation (%) is from 8 to 30 inclusive, and the number of recesses having a depth of 0.1 μm or greater is 10 or fewer.