PROCESS FOR PRODUCTION OF PULP

METHODE DE FABRICATION DE LA PATE A PAPIER

English Abstract

PROCESS FOR PRODUCTION OF PULP
Abstract of the Disclosure:
An improved process for the production of pulp charac-
terized by the employment of a novel type of cooking aid is
disclosed. The cooking is carried out in the presence of a
small amount of a compound selected from the group consisting
of hydroxyanthracenes and derivatives thereof. The cooking
yield is substantially increased and the quality of the
resulting pulp and paper is improved.
- 1 -

Claims

The embodiments of the invention in which an exclusive
property of privilege is claimed are defined as follows:
1. An improved cooking process for the production of pulp
from lignocellulosic material comprising cooking lignocellulosic
material in a cooking liquor,
the improvement comprising admixing in said cooking
liquor an amount, sufficient to increase the cooking rate of
said lignocellulosic material, of a cooking aid comprising at
least one member selected from the group consisting of compounds
having the formula:
<IMG>
wherein m is 0, 1 or 2, n is 1 or 2, R is COOA, SO3A
or H, and A is H or Na; providing that
when m is 1, R is at least one of COOA or SO3A and
R cannot attach to the middle ring;
when m is 0 or 2, R is H; and
when R is H and m is 2, two carbon atoms of the
anthracene nucleus lose their double bonds, and each such carbon
atom takes the form of CH2 instead of CH, in which case one H
of each CH2 is not counted as an R and may be substituted by
OA.
2. The process of claim 1, wherein said cooking aid is
at least one member selected from the group consisting of
dihydroxyanthracene, dihydroxydihydroanthracene, carboxydihydroxy-
anthracene and dihydroxyanthracene sulfonate.
3. The process of claim 1 wherein said cooking aid is
used in an amount of from about 0.005 to about 3% by weight
based on the bone dry weight of lignocellulosic material.
12

4. The process of claim 1, wherein said cooking aid is
used in an amount of from about 0.01 to about 0.1% by weight
based on the bone dry weight of lignocellulosic material.
5. The process of claim 3, wherein said cooking aid is
1,4-dihydro-9,10-dihydroxyanthracene or its sodium salt.
6. The process of claim 3, wherein said cooking aid is
1-hydroxyanthracene or its sodium salt.
7. The process of claim 3, wherein said cooking aid is
9,10-dihydroxyanthracene or its sodium salt.
8. The process of claim 3, wherein said cooking aid is
2-hydroxyanthracene or its sodium salt.
9. The process of claim 3, wherein said cooking aid is
9-hydroxyanthracene or its sodium salt.
10. The process of claim 3, wherein said cooking aid is
9,10-dihydroanthranol or its sodium salt.
11. The process of claim 3, wherein said cooking aid is
1,2-dihydroxyanthracene or its sodium salt.
12. The process of claim 3, wherein said cooking aid is
2,3-dihydroxyanthracene or its sodium salt.
13. The process of claim 3, wherein said cooking aid is
2,6-dihydroxyanthracene or its sodium salt.
14. The process of claim 3, wherein said cooking aid is
9,10-dihydroanthracene-9,10-diol or its sodium salt.
15. The process of claim 3, wherein said cooking aid is
9,10-dihydroxyanthracene-2-carboxylic acid or its sodium salt
13

16. The process of claim 3, wherein said cooking aid is
9,10-dihydroxyanthracene-1-sulphonic acid or its sodium salt.
17. The process of each of claims 1, 6 or 7, wherein
said cooking liquor is an alkaline process cooking liquor.
18. The process of each of claims 1, 6 or 7, wherein
said cooking liquor is a sulfite process cooking liquor.
14

Description

This invention relates -to a process for the production
of pul~. More particularl~Jr9 the inven-tion relates to a pro
cess for -the production of pulp from lignocellulosic materials
by carrying ou-t the cooking in the presence of a small amount
of a novel type of cooking aid selected from -the group con-
sisting of hydroxyanthracenes and derivatives thereof. The
cooking aid can be added to a cooking liquor in any of the
conventional alkaline, or sulfite or the like cooking proces-
ses. The term "alkaline cooking process" or simply "alkaline
process" herein used includes various alkaline cooking proces-
ses such as a kra~t process9 a soda process9 a sodium carbonate
process and the like. Similarly, the term "sulfite cooking
process" or simply "sulfite process" herein used includes
various sulfite cooking processes such as an alkaline sulfite
process~ a neutral sul~ite process, a bisulfite process, and
the like
In the field of producing pulp ~rom lignocellulosic
material such as wood, bagasse, hemp and the like, a number
of various trials have been repeated from old times to improve
the cooking yield, the rate of cooking and the quality of the
product pulp, aiming at the economical production of good
quality pulp with decreased consumption o~ raw material and
of energy. For example, instead of an ordinary kraf-t process
in which lignocellulosic material such as wood is subjected
to treatment by a cooking liquor comprising essentially sodium
hydrate and sodiw~ sulfide, a modified process thereo~ which
is usually called a "polysulfide process" and is characterized
by being sub~ected to treatment with a cooking liquor compris-
ing a sodium polysulfide is nowadays more popularly employed~
Various other modifications, for example, the addition of
~l~

borohydride5 hydra~ine, hydroxylamine or the like have also
been proposed and ~ried. Mos-t o~ such modified processes,
however, have not been fit for practical use because in some
cases to-tal or partial change of the processing equipment is
required, in other cases -there is a significant increase in
production cost, and in other cases the process is not appli-
cable to soft or hard woods or both. Thus, except for said
polysulfide process, none of the above-mentioned prior art
processes is more than a laboratory model.
10Accordingly, the object of the present invention is to
provide a novel process for the production of pulp completely
~ree from the disadvantages men-tioned above. The novel process
of the present inven-tion is characterlzed by the selective use
of a specific type of a cooking aid comprislng at least one
member selected from the group consisting of hydroxyanthra4enes
and the derivatives thereof. More particularly, in one aspect
of the present inven-tion, there is provided a process for pro-
; ducing alkaline pulp by carrying Ollt the cooking of lignocel-
lulosic materials such as wood, bagasse, hemp and the like in
an alkaline cooking liquor in the presence of a small amount
of hydroxyanthracene or a derivative -thereof which is added
as a novel type of cooking aid~ In another aspect of the
presen-t invention9 there is provided a process for producing
sulfite pulp by carrying out the cooking of said lignocellu-
losic materials in a cooking liquor comprising sulfi-te in the
presence of a small amount of the same cooking aid as mentioned
above. As a result of effecting the cooking of such lignocel-
lulosic materials as mentioned above in the presence of a
specific amoun-t of said novel cooking aid according -to the
~ 30 present invention, the solution veloci-ty of lignin from said
; - 3

lignocellulosic materials is substantially increased, and in
turn the rate of cooking is substantially increased too. The
cooking yield in pulp production is also substantiall~ improved
as compared with the prior art process using the same degree
of cooking. This is because hydroxyanthracene or a deri~Jative
-thereof added to the cooking liquor functions as a cooking aid
to promote the dissolution of lignin into the cooking liquor
as well as to prevent the degradation of cellulose and hemicel-
lulose throughout the cooking treatment. As a result of usi~g
such a novel cooking aid, the cooking yield and also the quality
of the resulting pulp are improved and the rate of cooking is
increased. Incidental to the increased rate of cooking, the
amounts of cooking chemicals and steam required for heating -
are also substantially reduced.
Typical compounds which can be advan-tageously employed
as said cooking aid in the practice of -the present invention
include hydroxyanthracenes and derivat-ves thereof having the
following general formula:
~ (OA)n ................................. (1)
wherein R represents H, COOX wherein X is H or Na, or SO3Y 20 wherein Y is H or Na9 A represents H or Na9 m represents O,
1 or 29 and n represents 1 or 2. The case wherein R represents
H in the above general formula refers to a case in which at
least one carbon atom in the anthracene nucleus loses its
double bond to change from CH to CH2 in the same position.
Namelyi the compounds defined by the above general formula
(1) include those to be ohtained by the addition of at least
one hydrogen atom to the carbon atom in the anthracene nucleus

fi~ 9
to have it lose its double bond and change from its CH form to
CH2 form in the same position, and include9 ~or example, the
compounds represented by the general ~ormulas:
Rm
~ (~)n ..... (2)
--I` ~J` , .
and
~ (OA)n
:
wherein R9 A, m and n have the same meanings as already defined.
Among those compounds, dihydroxyanthracene, dihydroxy-
dihydroanthracene9 carboxydihydroxyanthracene as well as
dihydroxyanthracenesulfonic acids including their sodium salts
and dihydroxyanthracene carboxylic acids including their sodium
salts can be most advantageously employed in the practice of
the present in~ention.
; These novel cooking aid co~pounds are pre~erably used
in an amount in the region o~ ODOO5 - 3% by weight based on
the bone dry weight of the raw material chips or the li~no
cellulosic materials -to be added -to the cooking liquor. I~
the compound is used in an amount in -the region of 0.01 - 0.1
by weight based on -the same standard, optimum best results
will be obtained.
Among compounds represented by the general formulas
(1) - (~) the dihydrodihydroxyanthracene can easily be
synthesized ~rom naphthoquinone, and butadiene by making
use o~ Diels-Alder reaction. For example9 if naphthoquinone
and butadiene are reacted with each other in a hydrophobic
solvent such as chloronaphthalene in the known Diels~Alder
-- 5 --
,

reaction as disclosed, for example9 in U S. Patent 2,938,913,
tetrahydroanthraquinone is obtained according to the equation
as shown below. This product changes, upon being dissolved in
an aqueous alkaline solution such as an aqueous sodium hydroxide
solution, -to an alkali salt of dihydrodihycLroxyanthracene, which
can be treated with an acid such as sul~uri.c acid9 hydrochloric
acid or the like -to precipitate dihydrodihydroxyanthracene,
Alternatively, te-trahydroanthraquinone can directly be treated
with an aqueous solution of an acid such as sulfuric acid to
obtain dihydrodihydroxyanthracene as a precipitate as disclo~ed
in USP 1,8909040, page 2, right column.
~ .
O O
3 + ~ in a
' ~, hydrophobic
¦¦ solvent
O O
:
N.Q. B.D. T.H.A.Q. (keto type)
/ ~ to dissolve
/ in aqueous
/ NaOH solution
~ ~ ;
OH / ONa
" ~ H2S4 / ~J~
1~ ~ J ~ ~ 3 ~ ) I
OH ONa
D.H.D.HPA.
(enol-type)
-- 6 --
~: .

7 ~;
~he cooking aid used in the pre~en-t invention is easy -to
dissolve in the cook.Lng li~luorO In order -to carry out the
process of the present invention, no special change is required
: with respec-t to the cooking conditions except that a specified
amount o~ said cooking aid is merely added to an ordinary
cooking ~LiquorO ~he following examples will illustrate the
preferred embodiments of the present inventionO
Example 1
600 g of softwood chips were placed in a ~-liter
: 10 capaci-ty autoclave, to which was added a kraft process cooking ~ .
liquor having 17% active alkali and 25% sulfidityO Then,
dihydroxydihydro~mthracene prepared by the process as explained ~.
hereinbefore in an amount of 0O05% by weight based on the bone
j dry weight of the chips was added -to the same cooking liquor
~` 15 and cooking was carried out a-t 165C for 75 minutesO
~ or comparative purposes, the same experiment was
repeated except that dihydroxydihydroanthracene was omittedO
he results of these experiments were as shown i.n ~able 1 ::
belowO
~ ;~
.' :
'.~
~ ....
~ 7 -
. .. . . .

Table 1
_~ . _, ____ _
Kraft process cooking Kraft process cooking
with dihydroxydihydro- without dihydroxydihydro-
anthracene anthracene
(presen-t invention) (prior art)
~,~
yield ~%) 48.6 46.5
number 42 51
IndeSt* 6.9 6.2
Breaking
len~th 8.2 7.0
f~G tcr i~0 170
:* determined by JIS P-8210 (Testing Method ~or Strength o~
Paper Pulp)
Exam~e 2
.
700 g of hardwood chips were place~d in a 4-liter
capacity autoclave9 to which a:soda process cooking liquor
having 15.5% (as Na20~ caustic soda and dihydroxyanthracene
; 5 in an amount of' 0.02% by weight based on the bone dry weight
of the chips was added and cooking was carried out at 155C . :~
for 75 minutes.
Next9 for comparative purposes, the same experiment
was repeated except that dihydroxyanthracene was omitted.
Ths results of these experlments are shown in Table Z below.
,: :
: - 8 -
. , ~ .

Table 2 ` ~ ~ ~
~ _ ~ ~
I Soda process cooking Soda process cooking
I with dihydroxy- without dihydroxy-
anthracene anthracene
(present invention) (prior art)
___
Cookin~
yield ~%) 53.9 5~.0
Kappa
number 50 78
Burst
Index* 4.3 3.0
Breaking
le ~th 6~1 4a 5
~ctor _ _ 100
~ ,
i * de-termined by JIS P-8210 (Te~ting Method for Strength of
Paper Pulp)
, :
, ~ :
700 g of hardwood chips were placed in a 4-liter
capacity autoclave, to which was added a sodium carbonate
process cooking liquor containing 10% sodium;carbonate and
5 O.l~o by weight, based on the bone dry weight of the chips,
of sodium dihydroxyanthracenecarboxylate and cooking was
carried out at 180C for 20 minutes. Then, the cooked chips
~ were beaten by a disk refiner to a freeness o~ 450 cc.
- For comparative purposes, the same experiment was
repeated except that sodium dihydroxyanthracenecarboxylate
was omitted. The results of these experiments are shown in ~ ~ `
Table 3 below. ~ ~
,:
"~
, ,
` ,
-

Table 3
Sodium carbonate process Sodium carbonate pr~c~ss
cooking with sodium cooking without sodium
dihydroxyan-thracene- dihydroxyanthracene-
carboxyla-te carboxylate
~present invention) (prior art)
~ ~, ,.
Cookin~
yield ~%) ~2.0 78.9
Burst
Index* 1.8 1.7
Breaking
len~th 3.2 2 ! 5
Folds 9
double 20 lL~
Rlng
crush 14.2 13.5
Resistance
Concora
¦ crush 19.5 19.0
Resistance
* determined by JIS P-8210 (Testing Method for S-trength of
Paper Pulp)
400 g of flax was placed in a 4-liter capacity autoclave,
to which was added a cooking liquor containing 18% sodium sul-
f'ite and 3% caustic soda9 bo-th based on the weight of raw
material9 and sodium dihydroxyanthracenesulfonate in an amount -~ --
of 0.05% based on the bone dry weight of the raw material and
cooking was carried out at 1~0C for 4 hours. Separa-tely9 for
co~parative purposes9 the same experiment was repeated except
that sodium dihydroxyanthracenesul~onate was omitted. The
resul-ts of these experiments are shown in Table 4 below.
-- 10 ~

Tablc 4
____
Sulfite cooking with Sulfite! ~o~k~g without
sodium dihydroxy- so~ dlh~droxy-
anthracenesulfonate an-thracenes~lfonate
(present i.nvention) (prior art~);
~_
Cooking
yield ~%) 62.5 58~5
Kappa
number 8 12
Breaking
len~th 8.9 7.6
Tear
~actor 190 170
__ ._ _ __._ _