| 摘要 |
A synthetic resin is incorporated in regenerated cellulose fibrous material by impregnating the material while it is still in the gel state, and before it has ever been dried sufficiently to convert it from the gel state to the non-gel state, with an aqueous liquid having a heat hardenable synthetic resin dissolved or dispersed therein, reducing the liquid content of the impregnated fibre, by squeezing, to less than the normal water imbibition value of the fibre in the gel state, and then drying and curing the impregnated material. "The water imbibition value" is defined as the percentage by weight of water retained in the saturated fibrous material after centrifuging a 0,5 gram sample for 5 minutes at 1,000G. The fibrous material may particularly be staple fibre. A list of resins which may be used includes urea-formaldehyde, melamine-formaldehyde, dicyandiamide-formaldehyde, guanidineformaldehyde, and methylol-amino-epihalohydrin condensation products. The water imbibition value of the fibres is preferably about 120%-150% (based on the oven-dry weight of the fibre) and the liquid content of the fibre is preferably reduced to about 60%-120%. The aqueous liquid may contain about 3%-20% of the resin, which is preferably in the monomeric or low polymer state with a molecular weight of the order of 100-1,000, preferably not exceeding about 600. It may also contain about 2%-20% (based on the weight of the resin) of a catalyst to aid the curing of the resin and 0,1%-4% of the weight of the liquid of a finishing agent. In an example, a blanket of freshly spun never-dried viscose rayon staple fibre still in the gel state after spinning and having a water imbibition value of 145% is squeezed between pressure rolls to a liquid retention of 100% on the weight of the oven-dried fibres. The blanket is then sprayed with a 9% aqueous solution of a 1 : 1 : 2 : 4, 5-urea-melamine-epichlorohydrinformaldehyde precondensate of the type described in Specification 796,815. The solution also contains 0,75% magnesium chloride hexahydrate catalyst and 0,15% of a polyglycol stearate softening agent. The impregnation is carried out in two steps with an intermediate squeeze and a final heavy squeeze to a final liquid rentention of 100%, the blanket opened, dried at 210 DEG F. and cured at 320 DEG F. In other examples, viscose rayon staple fibre is similarly impregnated with a mixture of acrolein-formaldehede and urea-formaldehyde condensate, acetone-formaldehyde condensate, and a polyepoxy-polyglycol condensate (Eponite 100), respectively. The process of the invention improves the subsequent processability of the fibres into yarn and cloth. U.S.A. Specifications 2,504,835, 2,696,477, 2,711,971 and 2,752,269 also are referred to. |
