A partially separated fiber bundle having a surface of a reinforcing fiber coated with a sizing agent containing a water-soluble polyamide-based resin, in which a separated fiber section consisting of a plurality of separated fiber bundles and an unseparated fiber section are provided alternately along a longitudinal direction of the reinforcing fiber bundle consisting of a plurality of single yarns, wherein the reinforcing fiber bundle contains 600 fibers/mm or more and less than 1,600 fibers/mm of fibers per unit width while the reinforcing fiber has a drape level of 120 mm or more and 240 mm or less.

A method of separating carbon fiber tows. The method includes separating two or more first carbon fiber tows from a first tow band onto a second elevation to form two or more second carbon fiber tows from a second tow band. The two or more second carbon fiber tows from the second tow band leave gaps next to first adjacent tows of the two or more first carbon fiber tows remaining from the first tow band after the separating step. The first adjacent tows from the first tow band leave gaps next to second adjacent tows of the two or more second carbon fiber tows from the second tow band.

A method of separating carbon fiber tows. The method includes separating two or more first carbon fiber tows from a first tow band onto a second elevation to form two or more second carbon fiber tows from a second tow band. The two or more second carbon fiber tows from the second tow band leave gaps next to first adjacent tows of the two or more first carbon fiber tows remaining from the first tow band after the separating step. The first adjacent tows from the first tow band leave gaps next to second adjacent tows of the two or more second carbon fiber tows from the second tow band.

A process for debundling a carbon fiber tow into dispersed chopped carbon fibers suitable for usage in molding composition formulations is provided. A carbon fiber tow is fed into a die having fluid flow openings, through which a fluid impinges upon the side of the tow to expand the tow cross sectional area. The expanded cross sectional area tow extends from the die into the path of a conventional fiber chopping apparatus to form chopped carbon fibers, or through contacting tines of a mechanical debundler. Through adjustment of the relative position of fluid flow openings relative to a die bore through which fiber tow passes, the nature of the fluid impinging on the tow, the shape of the bore, in combinations thereof, an improved chopped carbon fiber dispersion is achieved. The chopped carbon fiber obtained is then available to be dispersed in molding composition formulations prior to formulation cure.

A process for debundling a carbon fiber tow into dispersed chopped carbon fibers suitable for usage in molding composition formulations is provided. A carbon fiber tow is fed into a die having fluid flow openings, through which a fluid impinges upon the side of the tow to expand the tow cross sectional area. The expanded cross sectional area tow extends from the die into the path of a conventional fiber chopping apparatus to form chopped carbon fibers, or through contacting tines of a mechanical debundler. Through adjustment of the relative position of fluid flow openings relative to a die bore through which fiber tow passes, the nature of the fluid impinging on the tow, the shape of the bore, in combinations thereof, an improved chopped carbon fiber dispersion is achieved. The chopped carbon fiber obtained is then available to be dispersed in molding composition formulations prior to formulation cure.

A method of spreading fibres, the method comprises providing a continuous fibre bundle having an initial width W.sub.a and causing the fibre bundle to run, in a running direction, through tensioning means and past or through fluid flow means, the tensioning means intermittently varying the tension in the fibre bundle and the fluid flow means producing a fluid flow through the fibre bundle as the tension varies in the fibre bundle, whereby the width of the fibre bundle increases to a spread width W.sub.b. Apparatus (1) is also disclosed, which apparatus (1) comprises a tensioning means (3) to intermittently vary the tension in the fibre bundle (2) and a fluid flow means (4) for producing a flow of fluid through the bundle (2).

A method of spreading fibres, the method comprises providing a continuous fibre bundle having an initial width W.sub.a and causing the fibre bundle to run, in a running direction, through tensioning means and past or through fluid flow means, the tensioning means intermittently varying the tension in the fibre bundle and the fluid flow means producing a fluid flow through the fibre bundle as the tension varies in the fibre bundle, whereby the width of the fibre bundle increases to a spread width W.sub.b. Apparatus (1) is also disclosed, which apparatus (1) comprises a tensioning means (3) to intermittently vary the tension in the fibre bundle (2) and a fluid flow means (4) for producing a flow of fluid through the bundle (2).

A partially separated fiber bundle includes separation-processed sections and not-separation-processed sections that are alternately formed along the lengthwise direction of a fiber bundle that includes a plurality of single fibers, wherein the separation-processed sections include a plurality of divided fiber bundles that have been divided by separation processing. The partially separated fiber bundle is characterized in that the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform.

A partially separated fiber bundle includes separation-processed sections and not-separation-processed sections that are alternately formed along the lengthwise direction of a fiber bundle that includes a plurality of single fibers, wherein the separation-processed sections include a plurality of divided fiber bundles that have been divided by separation processing. The partially separated fiber bundle is characterized in that the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform.

A method of spreading fibres, the method comprises providing a continuous fibre bundle having an initial width W.sub.a and causing the fibre bundle to run, in a running direction, through tensioning means and past or through fluid flow means, the tensioning means intermittently varying the tension in the fibre bundle and the fluid flow means producing a fluid flow through the fibre bundle as the tension varies in the fibre bundle, whereby the width of the fibre bundle increases to a spread width W.sub.b. Apparatus (1) is also disclosed, which apparatus (1) comprises a tensioning means (3) to intermittently vary the tension in the fibre bundle (2) and a fluid flow means (4) for producing a flow of fluid through the bundle (2).