Note: Descriptions are shown in the official language in which they were submitted.
203~J'~
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PROCEDURE FOR THE PRO~UCTION OF PULP
The present invention relates to a process for the pro~
duction of mechanical pulp from a fibrous product.
The production of mechanical pulp from a fibrous pro-
duct, such as whole wood, wood chips, chips or refined pulp is
mainly implemented by mechanical methods~ The production of
mechanical pulp is based on the utilization of friction. Energy
is transferred to the wood in a compress-release process generat-
ing frictional heat which softens the wood so that individualfibres can be released.
Traditionally, mechanical pulp is produced either by
grinding or refining. These methods have the disadvantage of a
high energy consumption, but they also have the advantage of a
high yield (about 95~). In more advanced versions of the refining
method, heat (TMP, ~hermomechanical pulp) and possibly also chemi-
cals ~CTMP~ are used. Moreover, it has recently ~een established
that the energy consumption in the defibration and reining of
wood can be reduced by allowing white-rot fungi to act either on
~0 wood chips or on pulp produced by a single refining operation.
However, this method has the disadvantaye that the required reac-
tion time is several days, sometimes even weeks. Besides, the
reaction requires sterile conditionsO These circumstances are an
obstacle to large-scale and economical utilization of the method.
An object of the present invention is to create a solu-
tion that allows the refining energy requirement to be reduced
,'3 $~
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from its present level~ According to the invention, the fibrous
product is subjected to an enxyme treatment in which an enzyme
acts on lignin in the fibrous product. When the fibrous product
is treated with en~ymes acting on lignin, generated e.g. by white-
rot fungi, in the presence of suitable deoxidants, antioxidants or
salts, a reduction in the refining energy is achieved even if a
short reaction time i5 used, and no sterilization o~ the raw mat-
erial is necessary.
In the procedure of the invention, the raw material sub-
jected to enzyme treatment may be either whole wood, wood chips,or pulp refined one or more times. ~owever, the enzyme action re-
quires a good contact with as large a fibre area as possible.
The purpose of the en~me treatment is to modify the
structure of the lignin in the fibres ih such a way that the
fibres will come apart more easily during mechanical refining~
The desired result is achieved by treating the fibrous product
with an oxidizing enzyme and adjusting the redox pstential with a
suitable oxidation-reduction chemical. The enzyme to be used is
pre~erably phenoloxidase, lignin peroxidase, manganese peroxidase
or a mixture of these. A most suitable enz~me is phenoloxidase or
laccase produced by white-rot fungus Coriolus versiculum. ~he
temperature range of the en2yme treatment may he 10-90~, prefer-
ably 40-70C, and the pH range 2.0-10.a preferably 4.0-8Ø When
oxidizing enzymes such as phenoloxidase, li~nin peroxidase and
manganese peroxidase are used, it is preferable to adjust the
redox potential to the optimum level characteristic of each
3 - - 74131-1
oxidation-reduction enzyme by means of suitable oxidation-
reduction chemicals or redox regulators, e.g. gaseou~ nitrogen or
oxygen, antio~idants, sugars or sugar derivatives, organic acids
or inorganic salts, used either by themselves or in mixtures.
In the following, the invention is described in detail
by the aid of examples of embodiments based on laboratory tests.
Example 1.
2000 g of once-refined TMP spruce wood pulp was elutri-
ated in tap water so that the mixture obtained had a consistencyof 2.9% By adding Coriolus versiculum laccase enzyme to the
. . . _ _ .
mi~ture, a misture with a lacasse activity of 0.5 ~/ml and an
initial redox potential of approx. 100mV as measured against the
Ptelectrode was obtained. The temperature of the mixture during
the enzyme treatment was 20 C and the treating time was 30 min.
After the enzyme treatment, sodium hydroxide ~in an
amount of 4% of the dry matter of the mixture) was added to the
mixture. The mixture was then stirred manually for 30 min.,
whereupon it was concentrated, centrifugalized, homogenized and
frozen.
The pulp was refined in a Sprout ~ldron d 30 cm refiner
with a diminishing blade distance~ The refining energy was mea-
sured, whereupon a sample of 200 g (average) was taken. The sam-
ple was analyzed to determine its freeness value (C5F), fibre dis-
tribution, fibre length and shives content. In addition, a
3 ~i
~ ~ ~ 74131--1
circulation water sheet was produced from the sample and analyzed
to determine its density, tensile index, tear index, light scat-
tering coefficient, light absorption coefficient and blue reflec~
tance factor.
Tables 1 and 2 show the results of the analytical tests
reflecting the refining result and the quality of the pulp. In
addition to the above-described test (test 3) illustrating the in-
vention, two reference tests (tests 1 and 2) and two additional
tests (tests 4 and 5) were carried out. The results of these
tests are also presented in Table 1 below. The tests were
performed as follows:
rrest 1 (rePerence test): No enzyme treatment and no water
treatm~nt of the pulp was carried out before refining.
Neith~r was the pulp subjected to an alkali treatment. The
refining and analyses were performed as above (test 3).
Test 2 treference test): No enzyme treatment of the pulp
was performed, but the pulp was treated with tap water in
conditions corresponding to those of the enzyme txeatment
in test 3. In all other respects, the treatment corre-
sponded to that described above (test 3).
Test 4: The pulp was subjected to an enzyme treatment in
which the reaction mixture contained ascorbic acid in an
amount of 0.3 g/l. Otherwise the test corresponded to that
described above (test 33. The procedure represented by this
test is within the scope of the present invention.
Test 5: The pulp was subjected to an enzyme treatment in
which the reaction mixture contained ascorbic acid in an
amount of 0.3 g/l and 10 mM of sodium chloride. Otherwise
the test corresponded to that described above ~test 3). The
procedure represented by this test is within the scope of
the present invention.
It can be seen from the results that the refining energy
can be reduced during the first refining operation if
once-refined l'MP pulp is subjected to an enzyme treatment
as provided by the invention.
It can also be seen that the the blue reflectance factor
and certain strength properties were better than in the
case of the control pulp.
It is obvious to a person skilled in the art that the
invention is not restricted to the embodiment described
above, but that it may instead be varied within the scope
of the following claims.
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TABI.E 2
TEST 2 TEST 3 TEST 4 TEST 5
Untreated ¦ Pulp with ¦ Pulp with ¦ Pulp with
pulp ¦ laccase ¦ laccase and ¦ laccase,
¦ ¦ ascorbic acid ¦ ascorbic acid
¦ and NaCl
~'
CSF E ¦ CSF E ¦ CSF E ¦ CSF E
MJ/kg ¦ MJ/kg ¦ MJ/kg I MJ/kg
. _ I . . . I ~ .. . :
410 1 410 1 410 ¦ 410
1.35 ¦ 1.27 ¦ 1.35 1 1.16
330 ¦ 320 ¦ 315 ¦ 315 ,
... I
E = refining energy
CSF = freeness
