Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
`-- ~3~65~i10 `~
--1--
n ~
This invention relates to the control of pitch in
the manufacture of pulp and paper.
It is well known that "pitch" can accumulate in
paper making and also in the manu~acture of pulp, causing
significant problems. ~Pitch" is the term used to describe
the sticky materials which appear in paper maklng; these
originate from the wood from which the paper is made.
However, nowadays when more recycled paper is used, ~pitch"
is now used as a general term for all material soluble in
organic solvents but not soluble in water, for example the
ink or adhesive present ~n recycled paper. The pitch can
accumulate at various points in the system. For example,
it can block the felt and thus hinder drainage of the paper
web. In addition, it can adhere to the wires or drying
cylinders causing it to pick holes in the paper. Deposits
may also build up at any earlier stage in the papermaking
process. When these deposits break loose they may form a
defect in the paper such as a spot or a hole. Such defects
may even create a weakness in the paper sufficient to
induce a breakage in the paper during the production
resulting in unappreciated production down-time.
Many mater$als have been used in an attempt to
eliminate these problems. Such materials include inorganic
treatments such as talc and anionic dispersants. However,
conventional dispersants can be ineffective ~n a closed
system as there can be a build-up of "pitch". In such
- ~31~6~70
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systems the pitch particles have to be removed from the
water system in a controlled way without being allowed to
accumulate on the felt or rolls or, for example, the pipe
work used in the paper making machinery. These products
have also been found to give a limited effect and there is
a need for further improved treatments.
It has now been found, according to the
present invention, that certain water soluble poly-
quaternary amines are particularly effective for this
purpose. Accordingly, the present invention provides a
method for the control of pitch in an aqueous system
used in pulp or paper making which comprises adding to
the system, or to the pulp making or papermaking
machinery, a water soluble polyquaternary branched
polymer derived from (a) an epihalohydrin, a diepoxide
or a precursor of an epihalohydrin or diepoxide, (b) an
alkyl amine having a functionality with respect to an
epihalohydrin of 2 and (c) an amine having
functionality which has a functionality with respect to
an epihalohydrin of greater than 2 and which does not
possess any carbonyl groups under one or more of the
following conditions: i) the polymer is added to the
pulp making or papermaking machinery, ii) the pulp is
of recycled paper containing adhesive, and, iii)
components (a) and (b) are reacted to form a coupling
agent which is then reacted wi~h component (c).
1306St~O ~
-2a-
A special feature Oe the products u~ed in the
present invention is that they may combine with dissolved
anionlc material originating from the wood from which the
pulp and paper is produced, providing a method of removing
these anionic materials thereby lowering the concentration
of such materials in the process water. Water soluble
anionic materials are released from the wood during pulp
manufacture. These components interfere with paper
-.~.,
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production negatively in several ways: they decrease the
efficiency of many products used in the papermaking process
to alter the character of the paper. Examples of such
additives include sizes, wet and dry strength agents and
dyes. Anionic dissolved materials also reduce the
efficiency of retention agents. They limit the extent to
which the water system can beclosed and they may also lower
the quality of the paper such as its strength. Reference
is made to TAPPI papermakers Conference 1979 p49-66 which
further discusses, the significance of anionic dissolved
materials.
Component (a) is preferably an epihalohydrin,
especially epichlorohydrin or epibromohydrin, but
dihalohydrins, preferably dichlorohydrins or
dibromohydrins, having three to twenty, especially three to
ten, carbon atoms per molecule may also be used. Typical
dihalohydrins which may be used include the following:
CH ClCHClCH OH
2 2
CH2ClCH2(OH)CH2Cl
CH3CHClCHClCH2OH
CH3CHClCH(OH)CH2Cl
CH3CH2CHClCHClCH20H
CH3CHClCHClCH(OH)CH3
cH3cH2cHclcH(OH)
CH3CH2cH(oH)cHclcH
CH3CHClCH(OH)CHClCH3
13065~0
--4--
CH3CCHClCH2Cl
OH
j~3
CH2ClfCHClCH3 and
OH
CH2 (OH ) C-CHClCH3
As regards component (b) the alkyl amine may be a
compound possessing two tertiary amino groups such as
N,N,N',N'-tetramethyleneethylenediamine. Details of the
preparation of products derived from such component (b1 and
component (a) can be fo~nd in UK-A-l 486 396. However,
component ~b) is preferably a dialkylamine in which the
alkyl groups individually contain one to three atoms.
Dimethylamine is esPecially preferred.
As previously indicated, component (c) is an
amine which possesses a functionality greater than two with
respect to epihalohydrin and which does not possess any
carbonyl groups; it can therefore act as a branching agent.
It has been found that the use of a branched polymer is an
important feature in the performance of the polymer to
13~65`~0
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prevent deposition of pitch, as the comparative experiments
below show. ~ primary amino group is capable of reacting
with three molecules of epihalohydrin so that a simple
primary amine possesses a functionality of three.
Likewise, a simple secondary amine will possess a
functionality of two and a simple tertiary amine a
functionality o~ one. Accordingly, component (c) is
typically ammonia, a primary amine, a primary alkylene
polyamine having four to twenty-five, preferably four to
twelve, carbon atoms and at least one, preferably one to
six, primary amino groups per molecule including
polyglycolamines as well as aromatic and heteroaromatic
diamines but not polyamidoamines because they possess
carbonyl groups. Preferred materials include ammonia,
diethylaminobutylamine, dimethylaminopropylamine and
ethylenediamine, the latter two being especially preferred.
If desired, the polymer may also be derived from
a further component which generally has the ability to act
as a "end-capping" agent. In general, these materials will
also be amines or other material having reactivity towards
epichlorohydrin and which possess a functionality less than
two and which also possess some other functional group or a
fatty chain of, say, at least 12 carbon atoms, such as a
simple tertiary amine such as a trialkylamine, especially
trimethylamine or a hydroxyalkylamine, typically
triethanolamine, or a fatty amine such as octadecylamine.
The polymers used in the present invention may be
13V6S~O
prepared by first reacting components (a) and (b) to obtain
a "coupling agent" and then reacting this with component
(c) and, if desired, the fourth component. Preferred
polymers for use in the present invention include those in
S which the coupling agent is derived from epichlorohydrin
and dimethylàmine, which is subsequently reacted with
ethylenediamine and, iE desired, also with trimethylamine,
triethanolamine or octadecylamine.
The polymers may also be prepared by reacting a
mixture of components (b) and (c) with component (a). The
preferred raw materials for such a process are the same as
those given above.
In general, the reaction is carried out in an
aqueous medium, typically maintaining the reaction
temperature at 5 to 125C, preferably 30 to 95C. The
equivalent ratio of component (b) to component (c) is
suitably 1:0.009 to 1.0 and preferably 1:0.02 to 0.5 while
the equivalent ratio of component (a) to components (b) and
(c) may vary widely depending on the amount and nature of
component (b). Generally, the ratio of component (c) to
component (a) and component (b), together should be
selected so that the viscosity of the aqueous polymer
solutlon is at least 20 Cps at 50~ dry content. Typically,
the ratio is from 1:0.22 to 2.5 and preferably 1:0.25 to
1.3. In general, the reaction can be continued until the
desired viscosity, and therefore molecular weight, has been
achieved although acid can be used to reduce the pH and
1306S~0
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thereby terminate the reaction. A pH of 1 to 7.5,
especially 2 to 6.5, is generally preferred for the inal
solution.
The upper viscosity limit is not critical
provided it is consistent with having a workable solution;
the upper limit is normally about 2000 Cps.
Further details regarding the polymers which can
be used and their preparation is to be found in, inter
alia, UR-A-2 085 433, US-A-3 855 299 and US Patent Re-Issue
28 808 and, for certain polymers, in "Polyelectrolytes for
Water and Wastewater Treatment", ed W L K Schwoyer, CRC
Press Inc, pages 26 - 35. A particularly preferred polymer
for use in the present invention is formed by reacting
ethylenediamine with a precondensate of dimethylamine and
epichlorohydrin, and reacting the product with
triethanola~ine to form a water-soluble reaction product.
Another preferred product is formed by reacting a mixture
of dimethylamine and ethylenediamine or
dimethylaminopropylamine with epichlorohdyrin to form a
water-soluble reaction product.
The polymer is generally added to the aqueous
system with the furnish containing the paper pulp but it is
possible to add it at different points in the system
depending on the precise nature of the problem.
2~ The amount of polymer required will, of course,
depend to some extent on the nature of the wood or other
material used to prepare the paper pulp. Also, some
~ ~V65~70
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polymer once added will tend to recirculate in the system
thus requiring a lower addition rate. In general, however,
from 0.1 to 20 ppm of polymer by weight based on the
aqueous medium is suitable. Pre~erably, the amount is 1 to
10 ppm. This corresponds in the normal cas~ to an addition
of lo to 2,000 grams, preferably 100 to 1,000 grams,
polymer per tonne fibre. ~owever, in cases where the
polymer is required to neutralize anionic dissolvea
materials, generally higher amounts are desirable, in the
normal case from 1,000 grams to 50,000, especially from
1,500 to 1~,000 grams, per tonne fibre depending on the
process by which the fibres are produced (see, for example,
Progr. Colloid & Polymer sci. 65, 251-264 (1978) for a
discusssion of the amounts of anionic material likely to be
present). Fibres produced by a mechanical process
generally require a higher addition than fibre prepared by
a chemical process. It is, of course, also possible to
only partly neutralize the total amount of dissolved
anionic materials. In such cases amounts from as little
as, say, 10 grams per tonne of paper may be effective.
Sometimes it can be preferred to spray the
reaction product used in this invention onto a particular
part of the pulp- or paper-making machinery such as the
wire or press felts. In such cases, the polymer is
preferably pre-diluted with water, generally to a
concentration below 10~ by weight and preferably 1 to 5% by
weight.
13065'70
In some instances, it will be convenient to add
the polymer together with a biocide. Examples of suitable
biocides include those in the :Eollowing classes:
(i) a substituted 5- or 6-membered ring
heterocyclic compound in which the hetero atom or atoms are
one or more of nitrogen, oxygen or sulphur and the
substituent is an alkyl group, a keto group or a hydroxyl
group or a halogen atom, such compounds include
isothiazolones, and in particular, those having the
formula:
S - ~ R
CH - N
wherein R represents hydrogen or chlorine. A blend of
these two isothiazolones is commercially available, the
weight ratio of the chloro-substituted compound to the
unsubstituted compound being about 2.66:1;
(ii) a phenol or chlorinated phenol such as
pentachlorophenol
(iii) an amine or amide including
2,2-dibromo-3-nitrilopropionamide;
(iv) an organic cyanide or thiocyanate,
particularly methylene bis(thiocyanates3;
(v) a sulphone including halosulphones,
particularly hexachlorodimethylsulphone:
13~6S~
--10--
(vi) a straight chain aliphatic aldehyde,
particularly glutaraldehyde;
(vii) a triazine, particularly thio and/or
amino-substituted alkyl triazines;
(viii) bis bromo acetoxy butene- and
( ix) a dithiocarbamate, especiallY the
monomethyl, dimethyl, monoetnyl and diethyl derivatives,
typically in the form of sodium salts.
The polymer is generally compatible with the
usual pulp and paper making additives including starch, for
example potato or corn starch, titanium dioxide, a de-
foamer such as a fatty acid alcohol, a size, for example a
rosin size based on abietic acid, a neutral size based on
alkyl ketene dimer or a succinic acid anhydride based size
and a wet strength resin such as, if neutral, an
epichlorohydrin polyamide or, if acid, a melamine- or urea-
formaldehyde resin.
The precise nature of the pH of the system is
unimportant since the e~fectiveness of the polymer is
substantially unaffected by changes in pH.
Some of the polymers used in the present
invention are commercially available, typically as aqueous
solutions containing a concentration of 40 to 50% per cent.
Typically, the compositions used in the present invention
will possess from 1 to 70%, especially 10 to 30~, by weight
of the polymer.
The following examples ~urther illustrate the
~30f~5~0
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present invention.
EXAMPLE 1
Into a reaction flask fitted with reflux
condenser, mechanical stirrer and thermometer were placed
183.5 g of 32.7% dimethylamine and 270g of water. 76.04 g
of 36% hydrochloric acid was added while maintaining a
temperature maximum of 35C by cooling. 208.12 g
epichlorohydrin was added during 30 minutes. Cooling was
applied to keep the temperature not above 4~C. This
temperature was maintained for two hours to produce a stock
solution of so-called "coupling agent". 176.9 g of the
aqueous solution of the coupling agent was, using the same
equipment, heated to 60C. 5.94 g of ethylenediamine was
added dropwise over a 30 minute period. The temperature
was then kept at 60C for one hour. The reaction mixture
was heated to 90C and 32.48 g of 30% trimethylamine was
added during ten minutes; gnc was then maintained for two
hours and the reaction mixture cooled to room temperature.
This reaction mixture had a total solids content of 40.7%.
EXAMPLE 2
using the equipment described in Example 1, 25.35
g of 36% hydrochloric acid was added to a mixture of 68.81
g of 32.7% dimethylamine solution and 121.4 g water. The
temperature was kept below 35C by cooling. 83.25 g
epichlorohydrin was added at such a rate that temperature
was maintained at 40C. This temperature was then kept for
one hour. The reaction mixture was heated to 60C and
1306S~0
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7.5 9 ethylene diamine was added over 15 minutes while
maintaining the temperature at 60c. This temperature was
kept for another 30 minutes. The reaction mixture was
heated to 90C and 37.25 g triethanolamine was added
dropwise over 30 minutes. This temperature was maintained
for a further two hours to complete the reaction. The
total solids content was 44.6%.
EXAMPLE 3
The products prepared in Examples 1 and 2 were
evaluated using essentially the method described in 1977
TAPPI paper makers Conference p 23-32 by Ch E ~arley. This
method is built on TAPPI Standard Method RC324 which is a
recognised method for evaluating depositability of pitch.
The standard pitch solution was prepared as described in
the above references. A synthetic pitch
emulsion/dispersion was prepared by adding one litre volume
of deionised water at 50C to the synthetic pitch to reach
a 1200 ppm concentration.
~ solution of calcium chloride was added to reach
a hardness of 340 ppm expressed as calcium carbonate. The
pH was adjusted to 8Ø To evaluate the products as pitch
control agents, the products were added to obtain a
concentration of polymer as specified in Table I. The
depositability of the pitch was evaluated according to the
procedure in the above references. The test duration was
always five minutes. The results are presented in Table I
(mg deposited pitch).
13(:~65'7~)
-13-
TABLE I
PRODUCTCONCENTRATION (PPM) DEPOSITED PITCH (MG)
~lank -- 280
Example 1 2 252
5 Example 1 10 2
Example 2 2 255
Example 2 10 28
COMPARATIVE EXAMPLE 1
An amino~last resin was prepared essentiall~
according to Example III in US Patent 3 582 461 for
comparison.
84 g tl mole) of dicyandiamide, 196 (2.4 moles)
of 37% by weight inhibited aqueous formaldehyde solution,
126 g tmole) o~ 85% active formic acid were charged into a
1 litre four neck flask equipped with an agitator,
thermometer and condenser. The mixture was agitated for
0.5 hours at room temperature. External heat was applied
to the reaction mixture and the mixture was heated to 60C
over a 0.5 hour period. The reaction temperature was
gradually raised from 60C to the boiling point of the
mixture. The exothermic reaction, which occurred when the
temperature was raised above 60C, was controlled by
intermittent cooling. The boiling point of the reaction
mixture was reached after three hours heating. The mixture
was boiled for 15 minutes and then cooled rapidly to 55C.
42 g of methanol was added to etherify free methylol groups
13~65'~0
-14-
and the mixture was agitated for 2.5 hours and then cooled
to 25C. The resulting reaction product was a water
soluble dicyandiamide-~ormaldehyde condensate in the form
of a clear water soluble syrup containing 40~ by weight
solids.
This resin was evaluated according to procedure
in Example 3 with the following results.
concentration (ppm) Deposit (mg)
Blank 299
2 ~ 93
10 ppm 80
COMPARATIVE EXAMPLE 2
Some other products with potential as pitch
control agents were evaluated following the procedure of
~xample 3 with the following results.
15 Product Concentration ~eposit (mq)
. . .
Blank - 299
Polyacrylate100 Ppm 212
Cationic starch 100 ppm 94
Paper makers' alum 100 ppm 41
EXAMPLE 4
To a mixture of 68.81 g of 32.7% dimethylamine
and 121.4 g water was added 25.35 g of 36% hydrochloric
130~;5~(~
acid dropwise over 30 minutes. The temperature of the
reaction mixture was not allowed to e~ceed 35C, some
cooling was req~ired. 83.25 g of epichlorohydrin was added
at such a rate that the temperature of the reaction mixture
was maintained at 40C. After the exothermic reaction was
completed the solution was maintained at 40C until it
became clear (1 hour). After heating to 60C, 7.5 g of
ethylenediamine was added quickly over 5 minutes. The
reaction mixture was maintained at 65C for a further hour.
The reaction mixture was then cooled to room temperature.
To 97.42 g of this solution was added 22.56 g
octadecylamine (2 moles) and 7.5 g 2-methoxy ethanol (to
assist solution). This slurry was slowly heated to 70C
and maintained at this temperature for 30 minutes. Further
heating to 75C produced a highly exothermic reaction which
required
external cooling to maintain a temperature of 75C. After
completion of the exothermic reaction, the mixture was
heated at 90C for 2 hours. The product, which was in the
form of a creamy emulsion, had a total solid content of
18%.
EXAM~LE 5
The product of Example 4 was evaluated using the
method described in Example 3, bu~ a different synthetic
pitch was used. This time a Pitch solution was made by
adding a mixture of 2.0 g tall oil and 20.0 g glycerol
ester of rosin to 10.5 g 5% potassium hydroxide to form an
13~6~'70
-16-
emulsion. This was then diluted with 1~7.5 g isoproPanol
and l10 9 acetone to form a clear pitch solution. l5 ml of
this solution was added to one litre water at 20C and a
hardness of 200 p~m expressed aS calcium carbonate. The pH
was adjusted to 3.0 using concentrated hydrochloric acid
and the test was carried out over three minutes.
Concentration (ppm) Deposit (mg)
Blank 250
2 72
3.5 23
7.5 Nil
COMPARATIVE EXAMPLE 3
Polydiallyl dimethyl ammonium chloride (poly
DADMAC) is another poly quaternary resin suggested at a
pitch control agent, in European Patent Application 58 621.
This resin was tested following the procedure in Example 5.
Concentration (ppm) Deposit (mg)
2 193
~0 1~ 27
COMPARATIVE EXAMPLE 4
trhe preferred type of quaternary compound for
control of pitch deposition in US-A-3 619 351 is a
~3C~
methyltriethanolamine. ThiS material was synthesiæed from
triethanolamine and dimethyl sulphate to form quaternary
ammonium methyl triethanolamine monomethyl sulphate. This
material was evaluated using the procedure in ~xample 3
with the following results:
Concentration (ppm) Deposit (mg)
Blank 130
10 ppm 16~
100 p~m 102
COMPARATIVE EXAMPLE 5
A resin was prepared only from dimethylamine and
epichlorohydrin following essentially the procedure of
Example 1 of US reissue 28,807. A 500 ml round bottom
flask equipped with condenser, mechanical stirrer,
thermometer and pH electrodes was used for the preparation.
92.5 grams (1.0 mole) epichlorohydrin was added to the
flask. 112.5 grams of 40% aqueous dimethylamine (45 grams
real, 1.0 mole) was added with vigorous stirring over one
hour keeping the temperature below 50C. Heating was
applied ~or another two hours at 50C whereafter 70g water
was added. The viscosity of this resin was determined to
be 72 cps and dr~ content was ~ound to be 47 percent.
EXAMPLE 6
The same equipment as in Comparative Example 5
i30Ç~7~)
-18-
was used: 63.S g water, 99 ethylenediamine and 121.99
aqueous solution (36.5%) of dimethylamine was added to the
reaction flask. 1709 epichlorohydrin was added over a
three hour period maintaining the temperature below 35C by
cooling. Temperature was then increased to 80C. 11.89
epichlorohydrin was added in six portions over three hours
and after the last addition the reaction mass was kept at
80C for an additional two hours, whereafter the product
was cooled to room temperature. The product was a pale
yellow slightly opaque liquid with a dry content of 65.8%
and a viscosity of 190 cps.
EXAMPLE 7
The same equipment as in Comparative Example 5
was used. Water t34.2g), dimethylamine (60.9g of an
aqueous 36.9~ solution) and ethylenediamine (1.5g) were
charged to the reaction flask. 51.0g epichlorohydrin was
added with vigorous stirring over 2 hours. Temperature was
raised to 80C and 10.6g epichlorohydrin was added in 9
portions over a 8 hour Period. The final product was a
slightly opaque, pale yellow liquid. Dry content of this
product was found to be 58.8~ and the viscosity approx 1000
cps .
EXAMPLE 8
The equipment of Comparative Example 5 was used.
~ resin was prepared in the following way: 112.5 grams 40%
~3~?~S'70
--19--
dimethylamine was added to the reaction flask together with
10.2 grams dimethylaminopropylamine. These two amines were
mixed and 102 grams of epichlorohydrin was added over 30
minutes with vigorous stirring maintaining a temperature of
30-40C. Temperature was then increased to 60C which was
maintained for 5 hours. During this period of time, 300ml
of deionised water was added in small portions. This resin
had a viscosity of 20 cps and a dry content of 33%.
EXAMPLE 9
The products of Comparative Example 5 and
Examples 6 to 8 were evaluated following the procedure of
Example 5 at an addition of l.Oppm polymer with the
following results:
15 Product Deposit (mg~
Blank 272
Resin of Example 7 201
Resin of Example 6 138
Resin of Comparative Example 5 228
20 Resin of Example 8 186
Blank 260
EXAMPLE 10
The resin of Example 6 was evaluated using the
method of Example 3. The following results were obtained:
13065'70
-20-
Concentration (ppm)~eposit ~mg)
slank 133
2ppm 121
5ppm 29
lOppm 6
EXAMPLE 1 1
In order to evaluate the usefulness of polymers
to combine with anionic dissolved components of paper pulp
the rollowing experiment was made:
A dried groundwood pulp from pine was
disintegrated for 30 minutes to prepare a 2.5% furnish.
The fibres were subsequently filtered off and the filtrate
was used to evaluate the capacity of the resins to combine
with dissolved anionic materials. The amount of anionic
material was determined with a streaming current detector.
Polyethyleneimine (PEI) was used as standard. The
efficiency to combine with anionic material was evaluated
by adding to the filtrate various amounts of resin,
stirring for 15 minutes and subsequently determining the
residual concentration of uncombined anionic material by
titration with the standard reagent. The results were as
follows:
l~Q65~0
PEI mg/l Filtrate
Blank 7,1
4ppm of resin of ~xample 7 4,8
8ppm of resin of Example 7 1,9
4ppm of resin of Example 8 4,6
8ppm of resin of Example 8 1,4
8ppm of resin of Example 2 ~,4
50ppm of resin of Example 2 2,3
