Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
913
This invention refers to a process for the prepara-
tion of alkali cellulose from a cellulose-containing raw
material.
In the preparation from cellulose-containing raw
material of fibres and films consisting of regenerated cellu-
lose, or of cellulose ethers consisting of such, such as
carboxymethyl cellulose, the first processing stage is gen-
erally the preparation of alkali cellulose. The method of
preparation according to known methods is in outline as
follows:
The cellulose pulp used as a raw material is treated
in a solution of sodium hydroxide (NaOH) of sufficient concen-
tration to change the cellulose to alkali cellulose. This
process, or steeping, is carried out either by submerging
the sheets of cellulose in a solution of NaOH or by making
slurry of cellulose in a solution of NaOH, for example such
that the cellulose content of the suspension, or slurry, is 5%.
The concentration of the NaOH solution used in the steeping
is generally in the range 17 to 22% NaOH.
The excess NaOH solution is removed by pressing so
that alkali cellulose is attained in which the NaOH content is
15 to 17% and the alkali cellulose content 30 to 35%. The
alXali cellulose obtained is flaked or shredded.
The alkali cellulose i~ aged by being kept exposed
to the influence of atmospheric oxygen at a temperature be-
tween 20C and 60C. During the aging the molecular chains
of the cellulose break down in such a way as to reduce the
average size of the molecules. The average size of molecules
desired is determined by variation of the temperature and
duration of the aging. The reaction can be accelerated by
the use of catalysts, for example salts of cobalt or manganese.
Alternatively it is possible to add to the shred~ed
i~4~3
cellulose only the quantity of NaOH solution required to ob-
tain the desired composition of alkali cellulose directly.
The usual cellulose-containing raw material used is
bleached sulphite pulp or pre-hydrolysed sulphate pulp. In
particular in the preparation from alkali cellulose of cellu-
lose xanthate solution or viscose, high quality requirements
are set for the cellulosic pulp used. In the preparation of
viscose it is especially important that the cellulose xanthate
prepared from the alkali cellulose be as completely soluble
as possible in order to avoid difficulties in the filtration
of the viscose. This requirement is met only by pulps spec-
ifically manufactured for the viscose industry, or so-called
dissolving pulps, which are either sulphite pulp or prehy-
drolysed sulphate pulps and have an alpha-cellulose content
which is generally in excess of 90/O.
Other pulps, in particular sulphate pulp for the
paper industry, have not been usable in the viscose industry,
because in particular with paper-grade sulphate pulp a viscose
is obtained which is of exceptionally bad filterability, con-
taining swollen gels and insoluble fibre particles. In thecase of sulphate pulp this is caused by the fact that in the
alkali cooking an inadequate quantity of structurally detached
areas is formed in the walls of the cellulose fibres for the
formation of alkali cellulose to begin. In an acidifying
cooking stage as in sulphite cooking or in acidifying pre-
hydrolysis, on the other hand, these areas are formed by the
removal of hemicellulose by the influence of hydrolysis.
The pulp industry, which earlier used the sulphite
method (acid cooking) more than the sulphate method (alkali
cooking), has continuously moved more and more to the use of
the sulphate method. No new sulphite pulp factories are con-
structed, and old sulphite pulp factories are closed down or
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1084913
converted to the sulphate method. The reasons for this are
both environmental and economic.
In the preparation of high alpha-cellulose content
sulphite pulp or, particularly, pre-hydrolysed sulphate pulp,
a part of the alpha cellulose is lost, giving a lower pulp
yield. This means that the price of the finished cellulose
rises, and rises in proportion to the alpha cellulose content.
If the alpha cellulose content is raised by 1%, the yield
falls by about 3%. The present price difference is such that
diqsolving pulp is approximately 30% more expensive than the
normal pulp used by the paper industry. ~or this reason it
would be advantageous to use, for example, paper-grade sul-
phate pulp in the preparation of alkali cellulose if there
were no technical obstacles. The advantages of sulphate
pulp would also be the low resin content and small polydis-
persity, which are important in respect of the quality of
viscose fibres in particular, notably from the point of view
of the tenacity.
According to Finnish patents nos. 41543 and 41544
it is possible with the so-called double steeping method to
prepare filterable viscose also with lower quality pulps, such
as normal sulphate pulp. In the process represented in these
patents the alkali cellulose is steeped again after the aging.
The disadvantage arises in comparison with the normal method
that twice the number of steeping presses are required, lead-
ing to higher capital and running costs.
By using various additives in the steeping lye an
improvement in the reactivity of the alkali cellulose has been
attempted, but this has met with only slight success. The use
of various additives in the steeping lye is known and to a
certain extent used in the industry. Additives are used inter
alia to disperse the pulp resins, to improve shreddability or
1~4~3
to improve the sulphidising (xanthation). However, for the
preparation of alkali cellulose dissolving pulp has always
been used and the quantities of additives used has been small.
Surprisingly, however, it has now been established
that by the use of a certain quantity of additives in the
steeping the reactivity of the alkali cellulose can be increas-
ed to such an extent that even by steeping paper-grade sul-
phate pulp a sufficiently reactive alkali cellulose can be ob-
tained for, for example, the preparation of viscose, which
previously was not possible.
One purpose of the invention, therefore, is to
realise a method by which the raw material basis of the viscose
industry may be changed from expensive, specifically-refined
dissolving pulp to ordinary paper-grade pulp, which is a com-
pletely different raw material from dissolving pulp.
~ he principal features of the invention reside in a
process for the preparation of alkali cellulose from a raw
material containing cellulose by reacting the raw material
with steeping lye, comprising using as the raw material cellu-
lose pulp manufactured by alkali cooking without prehydro-
lysation or by acid cooking without alkali extraction or both,
and adding to at least one of the cellulose pulp, the steeping
lye and the alkali cellulose at least one organic compound se-
lected from the group comprising alcohols, esters, ethers, ke-
tones, amines, acids and salts of such acids, imines and ali-
phatic hydrocarbons containing at least four carbon atoms.
The organic compounds added in the method according
to this invention normally contain a polyoxyethylene group, a
polyoxypropylene group or at least one hydrophobic, e.g. ali-
phatic, chain in which there are at least three carbon atoms,and at least one hydrophilic group, such as a hydroxyl group,
ether oxygen or a ketone group. In addition to these, simple
1~84~13
hydrocarbons are powerful additives.
Examples of effective organic additives in the
method according to this invention are:
1. Lecithin:
Lecithin proper or phosphatidylcholine (20%)
CH2-0-Rl
CH2-0-R2
CH2 0 1 0 CH2 H2N (CH3)3
o
Rl and R2 linoleic acid and oleic acid (C17H31 33C0 )
Phosphatidyl-ethanolamine (15%)
Phosphoinositides (20%)
Sugars, sterols, fatty acids etc. (10%)
Triglycerides (ca. 35%)
HO(c2H40)x(c3H6o)y(c2 4 Z
x, y and z, and also x + z, maximum 50
2. H0(c2H40)x(c3H6o)y(c2H4 )Z
x, y and z, and also x + z, maximum 50
3. R-(c2H40)x(c3H6o)y(c2 4 Z
x, y and z as above.
R = 1) Rl-0--- fatty alcohol, e.g. Rl = myristyl,
lauryl, stearyl, oleyl etc.
2) ~
~ alkyl phenol, e.g. R2 = nonyl
R2
3) polyhydric alcohol, e.g. soxbitol
4 / (c2H4o)x(c3H6o)y(c2H4o)z
R-N \
\(C2H4)X(c3H6o)y(c2H4o)zH
x, y and z as above.
9~3
R = alkyl, aryl or alkylaryl, such as fatty amine, e.g.
ethoxylate derivatives of myristyl, lauryl, stearyl,
oleyl etc. amines.
5. CH3
O = C / CH2
CH2-CH2 methyl-isobutylketone
CH3
6. CH3-CH2- CH2- CH2 CH2 butanol, primary and secondary
CH3- CH-CH2- CH2-OH amyl alcohols and alcohols
CH3 higher than these, such as
hexyl and octyl alcohols
OH
CH3-CH2-CH-CH2-CH3
7. CH2 ICH2
CH2 ~ CH2 piperidine
NH
8. fH2-CH2-0-CH2-fH2 monobutylether of
OH O-C4H7 diethyleneglycol
C6H14 --~ CloH22 petroleum ether
various isomers boiling range 100-120C
10. ICH2 CIH2 ethyleneglycol monoethyl
OH O.C2H5 ether
11. CH2-CH-CH-CH-CH-CH2 sorbitol
OH OH OH OH OH OH
1 2 CH2-0-CH2-CH2-0-CH2-CH triethyleneglycol
OH OH
--6--
10849~3
13- C3H7-0-C3 ~ di-isopropyl ether
14. (CH2O)X paraformaldehyde (= poly-
oxymethylene)
15. CH3-CH-fH2 and IH2_cH2_fH2 P P
OH OHOH OH
16. R . NH2 e.g. stearyl or cyclohexyl-
amines
17. NH2 C6H12NH2 hexane diamine
' 1 H35CO0Na Na-stearate
19. NaOOC C6H 12 COONa sodium salt of pimelinic
acid
20. fH2-O0C-C17H33 glycerol trioleate
CH-OOC-C17H33
CH2-Ooc-cl7H33
1. (C12H25 N ~ )+SO4- lauryl pyridinium sulphate
22. Rl fH COOR sodium salt of sulphonated
S03Na alkylester
Of these additives lecithin ha~ proved the most advan-
tageous.
Lecithin, its essence, another phosphatide or its de-
rivative is added to advantage at 0.01-20% of the quantity of
alpha cellulose, whereas organic ethers, esters, ketones, al-
cohols and/or derivative~ of pyridine are added, depending on
their quality, at 0.1-100% of the quantity of alpha cellulose.
In association with this discovery it has also sur-
prisingly been noted that the increasing effect which the subs-
tances mentioned in the invention have on the reactivity of
the alkali cellulose can also be exploited when dissolving
pulp is the raw material, so that for example in the prepara-
tion of viscose the quantity of carbon disulphide used may be
1084~3
reduced to about 20-30% of the quantity of alpha cellulose
and a lower NaOH content in the viscose than usual can be used.
The invention is explained in more detail hereinafter
with the aid of examples.
In the accompanying trial examples the filterability
of KW value given is not a standardised measurement, but one
whose value depends on specification parameters. The filter-
ability values used here may be grouped as follows:
KW value Filterability
100- 50 Excellent
50-100 Good
100-150 Average
150-300 Bad
300-800 Very bad
> 800 Unfilterable
ExamPle 1
Normal bleached pine sulphate pulp as used by the pa-
per industry, with an alpha cellulose content of about 87%,
was steeped as a 4% suspension in a steeping lye of concentra-
tion 225 g NaOH per litre at a temperature of 35C for 30 mi-
nutes. The steeping lye also contained 10 g per litre, i.e.
25% of the weight of alpha cellulose, of an alkylene oxide
fatty alcohol additive known by the trade mark of Marlox FK 64
and manufactured by Chemische Werke Huls AG. From the alkali
cellulose suspension an alkali cellulose mass was made which
was pressed at a pressing ratio of 3.2. The slightly shredded
alkali cellulose was aged for 18 hours at +40C and xanthated
for 2 hours at +35C using a quantity of carbon disulphide 35%
of the quantity of the alpha cellulose, then dissolved to vis-
cose containing 5.3% NaOH and 10.2% cellulose, with a viscosity
by the falling ball method of 48 seconds. The filterability or
KW value of the viscose was 49.
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1084913
In the same manner a control viscose was prepared,
but without the addition of Marlox FK 64, which had a KW
value of 2778.
Example 2
Viscose was prepared in the same manner as for example
1, but in the place of the Marlox FK 64 the steeping lye con-
tained 10 g per litre, i.e. 25% of the weight of alpha cellu-
lose, of a polypropylene glycol of average molecular weight
400, manufactured by Shell Chemical Co. m e viscose contained
5.2% NaOH and 9.6% cellulose, and the viscosity by the falling
ball method was 68 seconds. m e KW value of the viscose was
52.
ExamPle 3
Viscose was prepared in the same manner as for example
1, but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of the alpha cellulose,
of diethyleneglycol monobutylether. ~he viscose contained
5.0% NaOH and 9.8% cellulose, with a viscosity by the falling
ball method of 57 seconds. The KW value of the viscose was
51.
Example 4
Viscose was prepared in the same manner as for example
1, but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose, of
a mixture of secondary amyl alcohol isomers containing about
60% pentanol-2 and about 36% pentanol-3. ~he viscose contained
5.3% ~aOH and 9.9% cellulose, with a viscosity by the falling
ball method of 60 seconds. The KW value of the viscose was 53.
Example 5
Viscose was prepared in the same manner as for Example
1, but in the place of Marlox FK 64 the steeping lye contained
. 084~13
10 g per litre, i.e. 25% of the weight of alpha cellulose, of a
mixture of aliphatic hydrocarbons (petroleum ether) with a
boiling point between +100 and +120C. The viscose contained
5,2% NaOH and 9.7% cellulose, with a viscosity by the falling
ball method of 76 seconds. me KW value of the viscose was
75.
Example 6
Viscose was prepared in the same manner as for Example
1, but in the place of the Marlox FK 64 the steeping lye con-
tained 10 g per litre, i.e. 25% of the weight of alpha cellu-
lose, of piperidine. The viscose contained 5.4% NaOH and 9.5%
cellulose, with a viscosity by the falling ball method of 60
seconds. me KW value of the viscose was 69.
Example 7
Viscose was prepared in the same manner as for Example
1, but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose, of a
polyethylene-oxide polypropylene-oxide mixed polymer known by
the trade mark of Genapol PF 10 and manufactured by Farbwerke
Hoech~t AG. The viscose contained 5.1% NaOH and 9.8% cellulose,
and the viscosity by the falling ball method was 42 seconds.
m e KW value of the viscoYe was 37.
ExamPle 8
Viscose was prepared in the ~ame manner as for Example
1, but in the place of Marlox FK 64 the steepi~g lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose, of a
ethoxylated fatty amine known by the trade mark of Berol Visco
32 and manufactured by Berol Kemi AB. The viscose contained
4.8% NaOH and 9.8% cellulose, with a viscosity by the falling
ball method of 47 seconds. The KW value of the viscose was 61.
--10--
iO849~3
ExamPle 9
Viscose was prepared in the same manner as for example
l, but in the place of Marlox FK 64 the steeping lye contained
0.2 g per litre, i.e. 0.50% of the weight of alpha cellulose,
of an ethoxylated oleyl amine known by the trade mark of Gena-
min 0-020 and manufactured by Farbwerke Hoechst AG. The vis-
cose contained 5.4% NaOH and 9.6% cellulose, with a viscosity
by the falling ball method of 57 seconds. The KW value of the
viscose was 50.
Example 10
Viscose was prepared in the same manner as for example
l, but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose, of
a sodium ~alt of sulphonated alkyl ester, known by the trade
mark of Berol VMA-478 and manufactured by Berol Kemi AB. m e
viscose contained 5.2% NaOH and 9.7% cellulose, and the visco-
sity by the falling ball method was 43 seconds. The KW value
of the viscose was l9.
Example 11
Viscose was prepared in the same manner as for example
1, but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose, of
an alkylene-oxide alkyl phenol additive known by the trade mark
of Marlox NP 109 and manufactured by Chemische Werke H~ls AG.
The viscose contained 5.3% NaOH and 10.4% cellulose, with a
viscosity by the falling ball method of 46 seconds. The KW
value of the viscose was 59.
Example 12
Viscose was prepared in the same manner as for example
1, but in the place of Marlox FK 64 the steeping lye contained
0.1 g per litre, i.e. 0.25% of the weight of alpha cellulose,
of technical grade soya lecithin of 35% fat content. The vis-
10849~3
cose c~ntained 5.0% NaOH and 9.5% cellulose, with a viscosity
~y the falling ball method of 23 seconds. The KW value of the
viscose was 47.
A control viscose was prepared in the same manner but
without the addition of lecithin, giving a KW value of 2000.
Example 13
From normal bleached birch sulphate pulp as used by
the paper industry, with an alpha cellulose content of about
87%, viscose was prepared in the same manner as for example l,
but in the place of Marlox FK 64 the steeping lye contained
10 g per litre, i.e. 25% of the weight of alpha cellulose of
methyl-isobutyl-ketone. The viscose contained 5.1% NaOH and
9.4% cellulose, with a viscosity by the falling ball method of
20 seconds. The KW value of the viscose was 60.
A control viscose prepared in the same manner but with-
out the addition of methyl-isobutyl-ketone had a KW value of
1024.
Example 14
Visco~e was prepared in the same manner as for example
13, but in the place of methyl-isobutyl-ketone the steeping
lye contained 10 g per litre i.e. 25% of the weight of alpha
cellulose, of a technical-grade mixture of primary amyl alcohol
isomers manufactured by Union Carbide Chemicals Co. and contain-
ing approximately 60% pentanol-l and 40% 2- and 3-methyl-
butanol-l. The viscose contained 4.5% NaOH and 9.4% cellulose,
with a viscosity by the falling ball method of 13 seconds. The
KW value of the viscose was 49.
Example 15
Normal bleached pine sulphate pulp, as used by the
paper industry, with an alpha cellulose content of about 87%,
was steeped as a suspension of 4% in a steeping lye of strength
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1084913
225 g NaOH per litre, hemicellulose content 32 g per litre,
at a temperature of +55C for 30 minutes. The steeping lye
contained 0.2 g per litre, i.e. 0.50% of the weight of alpha
cellulose, of technical grade soya lecithin from which the
fatty content had been removed by extraction with acetone. The
alkali cellulose was pressed, aged and xanthated in the same
manner as in example 1. The viscose contained 5.3% NaOH and
9.6% cellulose, with a viscosity by the falling ball method of
37 seconds. The KW value of the viscose was 82.
Example 16
Coniferous wood sulphite dissolving pulp was steeped
as a 4% suspension for 10 minutes in a steeping lye of strength
225 g NaOH per litre at a temperature of 25C. The steeping
lye contained 0.1 g per litre, i.e. 0.25% of the weight of
alpha cellulose of technical grade soya lecithin. Alkali cel-
lulose was prepared from the suspension in the same manner as
for example 1. After ageing the alkali cellulose was xanthated
with a quantity of carbon disulphite 25% of the weight of al-
pha cellulose and the xanthogenate obtained was dissolved to
viscose, which contained 5.1% ~aOH and 9.6% cellulose, with a
viscosity by the falling ball method of 60 seconds. m e KW
value of the vi~cose was 58.
A control visco~e was prepared in the same manner but
without the addition of lecithin in the steeping lye, and gave
a KW value of 283.
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