The object of the present invention is to provide a method for producing fine fibers and a sheet containing fine fibers, whereby fiber refinement (fibrillating) of a fiber material is facilitated, freeness and dehydration performance of slurry containing fine fibers obtained after fiber refinement (fibrillating) is favorable and resistance to yellowing of the fine fibers is improved. The present invention provides a method for producing fine fibers, comprising at least the steps of: (a) introducing electrostatic and/or steric functional substituents into a fiber material to obtain substituent-introduced fibers; (b) subjecting the substituent-introduced fibers to mechanical treatment; and (c) eliminating some or all of introduced substituents from the substituent-introduced fine fibers obtained in step (b) to obtain fine fibers from which substituents have been eliminated.

The present invention relates to a process for manufacturing a composite article comprising cellulose pulp fibers and a thermoplastic matrix, wherein said process comprises the steps of: a) mixing a refined aqueous pulp suspension with a water suspension of thermoplastic fibers into a composition, b) forming the composition into a fiber web, c) dewatering the fiber web, d) drying the fiber web, and e) heating and pressing the dried fiber web from step d) to melt said thermoplastic fibers into a thermoplastic matrix and form a composite article.

The present invention relates to a process for manufacturing a composite article comprising cellulose pulp fibers and a thermoplastic matrix, wherein said process comprises the steps of: a) mixing a refined aqueous pulp suspension with a water suspension of thermoplastic fibers into a composition, b) forming the composition into a fiber web, c) dewatering the fiber web, d) drying the fiber web, and e) heating and pressing the dried fiber web from step d) to melt said thermoplastic fibers into a thermoplastic matrix and form a composite article.