Polyketone fiber and process for producing the same

Polyketone fibers comprising polyketone fibers having a minimum value of a UV absorbance (Amin (F)) observed in a wavelength region of 210 to 240 nm of 0.5 or less, said polyketone fibers being produced by a process satisfying the following (a), (b) and (c).

• (a) a polyketone containing 95% by mole or more, on the basis of the total repeating units, of a repeating unit represented by the formula (1) is dissolved in an aqueous metal salt solution which contains a zinc salt and at least one metal salt other than the zinc salt selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, iron, cobalt, nickel and copper to form a polyketone solution
• —CH2CH2—CO— (1),
• (b) a concentration of the zinc salt in the aqueous metal salt solution is 10 to 60 wt % and
• (c) the above obtained polyketone solution is injected through a spinneret, wherein when a period of time from dissolving the polyketone in the aqueous metal salt solution to injecting the polyketone solution through a spinneret is divided into minutes and the arithmetic mean of a heating temperature at t-1 minutes from dissolution of the polyketone and a heating temperature at t minutes therefrom is represented by Tt(K), the following formula (2) is satisfied, while the polyketone in the solution injected through the spinneret has a minimum value of a UV absorbance (Amin (S)) observed in a wavelength region of 210 to 240 nm of 0.5 or less
• S
• =
• ∑
• t
• =
• 1
• t
• =
• p
• ⁢
• 1.53
• ×
• 10
• 8
• ×
• [
• exp
• ⁡
• (
• -
• 8547
• /
• T
• t
• )
• ]
• ≤
• 1.00
• (
• 2
• )
• wherein t in (2) is a natural number from 1 to P (minutes), provided that when there is a fraction of less than 1 minute in the period from dissolving the polyketone in the aqueous metal salt solution to injecting the polyketone solution through a spinneret, the fraction is eliminated with the resultant period being P.