US 4,889,591 A · Crotalaria juncea paper pulps

Abstract

The present process produces a long fiber suitable for making various paper products. The long fiber is derived from Crotalaria juncea. The processing consists of a particular technique for preparing the fiber for digestion and a particular digestion sequence. In the preparation of the fiber for digestion it is dried to less than about 30 percent moisture, moist depithed, washed and wet depithed. The fiber is then processed at a high caustic concentration using a sequence of digestion-pressure reduction-digestion. Optionally there can be a third stage of digestion with a pressure reduction prior to the digestion. After digestion has been completed the fiber is refined and sent to blowdown. The fiber is then screened, washed and bleached. The resulting long fiber will product a high quality paper or is admixed with short fibers and various paper products can be made.

Claims20

Dependent claims

A method for producing a paper pulp using Crotalaria juncea as the primary source of long fiber comprising:

a. harvesting said Crotalaria juncea;
b. reducing the moisture content of the Crotalaria juncea to less than about 30 percent by weight;
c. reducing the size of the pieces of said Crotalaria juncea to smaller fragments;
d. shredding and depithing said Crotalaria juncea at its ambient moisture level;
e. washing the depithed Crotalaria juncea;
f. wet depithing the washed Crotalaria juncea;
g. contacting the washed and depithed Crotalaria juncea fibers with an aqueous solution comprising sodium hydroxide containing at least about 8 percent by weight sodium hydroxide at a temperature of greater than about 180.degree. C. for a first period of time;
h. rapidly reducing the pressure at least about 1 kg/cm.sup.2 with a resulting reduction of temperature and continuing the contact of said Crotalaria juncea fibers with said aqueous sodium hydroxide for a second period of time;
and
i. recovering a Crotalaria juncea paper pulp.

7 more elements

Dependencies are inferred from the claim text.

Crotalaria juncea paper pulps

Life of this patent

Crotalaria juncea paper pulps

Life of this patent

Abstract

Claims20