sulfate process ( sulfate pulp )
One of the two principal chemical methods of
converting wood into pulp for papermaking, the
other being the SULFITE PROCESS .
Today, the terms "sulfate" and kraft, when applied
to paper pulp, are generally used interchangeably,
although there are slight differences between
them. The term ' kraft" was first applied to the
strong brown paper produced from pulp made by the
sulfate process, and later to indicate the pulp
itself. Originally, the term "sulfate" designated
all paper pulps made by the sulfate process;
later, it was used strictly with reference to
special grades of pulp, such as bleachable sulfate
pulp, bleached sulfate, etc., while "kraft" became
restricted to that particular quality of
unbleached sulfate pulp which had been cooked so
as to produce a high yield or pulp of exceptional
strength. Today, however, the term "sulfate" is
generally used in the paper industry to indicate
all grades of pulp produced by a process which
utilizes sodium sulfate as it s principal chemical
constituent. The only exceptions to this common
practice are certain speciality grades of pulp,
such as easy-bleaching sulfates made from both
softwood and hardwood trees.
Sulfate pulps were first used primarily for the
production of various grades of paper and board
where physical strength was of greatest
importance. Although the stronger grades are
produced from the softwoods, very large quantities
of hardwood sulfate pulps are also produced.
Mixtures of hardwoods, with their longer fiber
improve the formation and surface features of the
paper or board. (17
, 72 , 143 , 198 , 320 )
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