Partially separated fiber bundle, production method of partially separated fiber bundle, fiber-reinforced resin molding material using partially separated fiber bundle, and production method of fiber-reinforced resin molding material using partially separated fiber bundle

Abstract

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 separated bundles. The content of the not-separation-processed sections is 3% or more and 50% or less of the partially separated fiber bundle.

1 .- 17 . (canceled) 
     
     
         18 . A partially separated fiber bundle in which separation-processed sections and not-separation-processed sections are alternately formed along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed sections being separated into a plurality of bundles, the partially separated fiber bundle being characterized in that the content of the not-separation-processed sections is 3% or more and 50% or less. 
     
     
         19 . The partially separated fiber bundle according to  claim 18 , wherein the length of each of the separation-processed sections is 30 mm or more and 1,500 mm or less. 
     
     
         20 . The partially separated fiber bundle according to  claim 18 , wherein the length of each of the not-separation-processed sections is 1 mm or more and 150 mm or less. 
     
     
         21 . The partially separated fiber bundle according to  claim 18 , wherein an entangled part and/or an entanglement accumulation part is formed at a boundary between the separation-processed section and the not-separation-processed section. 
     
     
         22 . A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers travels along a lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a separation processing time t1 during being penetrated with the separation means and a time t2 from being removed with the separation means to being penetrated again into the fiber bundle satisfy Equation (1)
   0.03≤ t 2/( t 1+ t 2)≤0.5  (1).
   
     
     
         23 . A method of producing a partially separated fiber bundle wherein a separation means provided with a plurality of projected parts is penetrated into a fiber bundle comprising a plurality of single fibers, while the separation means is traveled along the lengthwise direction of the fiber bundle, a separation-processed part is created, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after the separation means is traveled up to a position passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a separation processing time t3 during being penetrated with the separation means and a time t4 from being removed with the separation means to being penetrated again into the fiber bundle satisfy Equation (2)
   0.03≤ t 4/( t 3+ t 4)≤0.5  (2).
   
     
     
         24 . The method according to  claim 22 , wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, and the separation means is removed from the fiber bundle accompanying an increase of the pressing force. 
     
     
         25 . The method according to  claim 22 , wherein presence of a twist of the fiber bundle in a range of 10 to 1,000 mm from the separation means having been penetrated into the fiber bundle in at least one of the front and rear of the fiber bundle along the lengthwise direction of the fiber bundle is detected by an imaging means. 
     
     
         26 . The method according to  claim 25 , wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, a twist is detected by the imaging means, and the separation means is controlled so that the pressing force is reduced until the projected parts are passed through the twist from immediately before being contacted with the twist. 
     
     
         27 . The method according to  claim 22 , wherein a plurality of the projected parts are independently controllable. 
     
     
         28 . The method according to  claim 22 , wherein the separation means has a rotational shaft orthogonal to the lengthwise direction of the fiber bundle, and the projected parts are provided on a surface of the rotational shaft. 
     
     
         29 . A fiber-reinforced resin molding material comprising a reinforcing fiber mat obtained by cutting/spraying the partially separated fiber bundle according to  claim 18  and a matrix resin. 
     
     
         30 . The fiber-reinforced resin molding material according to  claim 29 , wherein the matrix resin is a thermosetting resin. 
     
     
         31 . The fiber-reinforced resin molding material according to  claim 29 , wherein the fiber-reinforced resin molding material is a sheet molding compound. 
     
     
         32 . A method of producing a fiber-reinforced resin molding material according to  claim 29 , comprising at least steps [A] to [C]:
 [A] a partial separation step of obtaining a partially separated fiber bundle by alternately forming separation-processed parts and not-separation-processed parts along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed parts being separated into a plurality of bundles;   [B] a matting step of cutting the partially separated fiber bundle and spraying the cut bundles to obtain a reinforcing fiber mat; and   [C] a resin impregnation step of impregnating a matrix resin into the reinforcing fiber mat.   
     
     
         33 . The method according to  claim 32 , wherein at least the steps [A] to [C] are carried out continuously in a single process. 
     
     
         34 . The method according to  claim 32 , wherein in the step [B], the partially separated fiber bundle is cut at an angle θ (0<θ<90°) with respect to the lengthwise direction thereof.