Note: Descriptions are shown in the official language in which they were submitted.
13~8~9
The present invention generally relates to a
chemical product for use in sizing organic cellulosic
fibres, especially in papermaking and in particular
in stock hydrophobation (sizing) during the papermaking
process. Sizing or hydrophobation of paper is an old
technique which derives from China. When the paper-
making technique came to Europe, it was found that
absorbent paper was less suitable for the pens and
ink used at the time. As early as the fourteenth cen-
tury, gelatin was therefore added to the paper to
obtain a hard, tight, non-absorbent paper. The sizing
technique using gelatin and starch has thereafter
been gradually improved.
At the beginning of the nineteenth century, the
sizing technique was dramatically improved by the
discovery of rosin size. In rosin sizing, the rosin
is precipitated by means of alum in the fibre suspension
prior to sheet formation. The resulting precipitate
is cationic and associated to the negatively charged
fibres. The aluminium resinate formed in the reaction
is very water-repellent (hydrophobic) and yields a
low-wetting paper product. The stock sizing technique
using rosin size/alum remained relatively unaltered
over the first 150 years. Later, the resin acid has
been modified by reacting it with e.g. maleic anhydride
and fumaric acid (so-called fortified rosin size).
In order that the size should be water-soluble, the
resin acid was saponified with soda lye and diluted
before addition.
1~3~4;3
An improvement of the last-mentioned technique
was made in the 1960's and 1970's by the use of so-
called dispersion size. This technique means that
the resin acid is dispersed to small anionic particles
(0.2-0.5 ~m) in an aqueous solution. The resulting
dispersion is stable and is added to the stock and
precipitated by means of alum.
Despite a certain further development during
different periods, the rosin sizing technique has
however remained basically the same as it was in the
nineteenth century, i.e. two components are required
for providing sizing, namely the rosin size and a
chemical precipitant based on an aluminium salt, such
as alum.
GB-Al-2,010,352 discloses another stock sizing
method in which a rosin size consisting of a saponi-
fied resin acid is added to the stock and thereafter
precipited on the fibres by admixing a practically
sulphate-free aluminium polyhydroxy chloride with
the stock containing the rosin size. According to
this British publication, the major advantage of using
this particular precipitant instead of alum is the
alleviation of corrosion problems. However, this known
sizing process makes use OL a two-component system
in which the conventional precipitant alum has been
replaced by another precipitant in the form of a spe-
cial aluminium salt.
German patent specification 363,668 also discloses
a two-component system, in which a rosin sizing agent
~ 33~8~9
is precipitated with a neutral or basic aluminium
chloride.
In addition to the rosin sizing technique, use
has been made of a similar sizing technique based
on saponified fatty acids of tall oil (see e.g. SE
Patent 7507128-2, Publ. No. 416,831) which are also
precipitated by means of an external precipitant,
such as alum.
A major drawback of the prior art sizing methods
is that the hydrophobing effect drops dramatically
in the case of neutral or alkaline paper systems.
This is an especially great problem when calcium car-
bonate should be used instead of clay as filler, since
calcium carbonate is dissolved at low pH. This defi-
ciency of conventional sizing is due to the fact that
cations of aluminium are required for precipitating
the negatively charged resin acid/fatty acid. In neutral
or alkaline systems, aluminium ions precipitate in
the form of aluminium hydroxide which is a poor precipi-
tant for rosin size, which in this case results in
a low sizing degree. This limitation is a particular-
ly serious problem in connection with sizing in neutral
or alkaline stock systems, since it is preferred,
in respect of both quality and economy, to use calcium
carbonate instead of clay as filler for e.g. fine
paper.
In addition to the conventional rosin sizing
systems, new synthetic sizes have also been developed
~3~843
which have gained ground in papermaking at neutral
or alkaline pH. Examples of sizing agents of this
type are alkyl succinic anhydride and alkyl ketene
dimer. These sizes are however considerably more ex-
pensive than natural sizing agents, such as resin
acids and fatty acids. Another drawback of these known
synthetic sizes is that they require an extended time
for producing the desired sizing effect as compared
with the setting time for resin acid-based or fatty
acid-based sizes. The prolonged time for the synthe-
tic size means that the paper immediately after form-
ing will not have completely water-repellent proper-
ties after the drying section of the papermaking machine.
An extended setting time implies drawbacks in
connection with surface sizing and/or surface coating
of the paper directly after predrying. A low sizing
degree (when using alkyl ketene dimer sizing) therefore
often entails excessive rewetting of the paper, which
may cause web rupture and reduced productivity. Moreover,
sizing with such neutral sizing systems may entail
low paper friction and problems with deposits on dif-
ferent parts of the papermaking machine system. These
production problems have therefore been one of the
reasons why rosin sizing in acid stock systems contain-
ing clay as filler still is the predominant hydrophobing
technique. Another reason is the substantially higher
price of synthetic sizes as compared with the price
of resin acid- or fatty acid-based sizes.
8 ~ ~
British patent specification 1,107,717 also dis-
closes sizing systems comprising an emulsion of paraf-
fin wax as dispersed phase and an aqueous solution
of a basic aluminium chloride as continuous phase,
the emulsion being stabilized with non-ionic emulsi-
fying agents and/or non-ionic thickening agents. As
examples of other hydrophobic materials than paraffin,
mention is made, but no specific examples given, of
microcrystalline waxes, polyethylene and related waxes,
high molecular weight fatty alcohols and high molecular
weight fatty amides. It has however been found that
such sizing systems do not produce the aimed-at effect.
The same applies to the sizing system disclosed in
British patent specification 1,274,654, which is also
based on a combination of the same substances. Common
to the sizing systems according to these two patent
specifications is that the papers sized by means of
these systems are spotty, which is indicative of uneven
distribution of the sizing agent.
Another drawback of known sizing systems is that
they are adapted for use either in acid stock systems
or in neutral or basic stock systems. This means dif-
ficulties for paper mills desiring to switch from
e.g. acid stock systems to neutral or basic ones.
Such switch-over in fact means changing several cor-
related factors, where the change-over from one sizing
system to another entails considerable initial pro-
duction problems. Thus, there is a need for a sizing
~t 339~43
system which can be used in both acid and neutral
or basic stock systems, since the switch-over problems
would then be substantially reduced.
A primary object of the present invention therefore
is to provide a stock hydrophobing agent which overcomes
the limitations from which conventional techniques
suffer. Another object of the invention is to provide
a hydrophobing agent which can be used as a single-
component agent without the need of separately adding
chemical precipitants. Yet another object of the inven-
tion is to provide a method of preparing such a novel
hydrophobing agent. A further object of the invention
is to provide a sizing system which can be used in
both acid, neutral and basic sizing systems.
The invention is based on the unexpected discovery
that it is possible to obtain a stable single-component
agent which is usable as sizing agent and which does
not require an external precipitant (as opposed to
conventional resin-based or fatty acid-based sizes),
by combining certain polyaluminium salts, one or more
resin acids and/or fatty acids, optionally in admixture
with a melting point lowering additive, such as paraf-
fin, or other hydrophobic melting point lowering agent,
and preferably also a cationic organic substance at
low pH (below 4). This sizing agent consists of small
emulsified (dispersed), strongly cationized particles
which will be directly adsorbed on the negatively
charged fibres when supplied to the paper system or
when applied to other organic fibres.
~ ~3~8~
The hydrophobing agent according to the invention
thus consists of resin acid and/or fatty acid which
has been emulsified/dispersed in an aqueous phase
of water, a polyaluminium salt dissolved in the water
and preferably also a cationic organic compound. The
hydrophobing agent is prepared by finely dispersing
the resin acid and/or fatty acid in the aqueous phase
in the presence of the polyaluminium salt and preferably
also the cationic organic compound. The invention
also relates to the use of this hydrophobing agent
for stock hydrophobation of cellulosic fibres in paper-
making.
One of the advantages of the invention is that
the polyaluminium salt and the resin acid and/or fatty
acid are combined at low pH (below 4), a direct acti-
vation occurring when the hydrophobing agent is charged
to the stock and a precipitate of a compound of alumi-
nium and resin acid and/or fatty acid is formed when
the emulsion droplet enters into the pH range 4-6.
The invention provides for intimate contact between
the resin acid and/or fatty acid and the polyaluminium
salt, such that the aluminium hydroxide, despite high
pH in the papermaking process, will not have time
to precipitate before the formation of the active
resin acid/fatty acid resinate. Another advantage
of the hydrophobing agent according to the invention
is that the small emulsified/dispersed particles,
by their small size, will optimally cover the surface
to be hydrophobated.
~ ~3~49
A very substantial advantage of the invention
is that no external precipitant is needed. This means
a considerable simplification for anyone who wishes
to perform hydrophobation, especially in papermaking,
not only because only one substance need be charged
but also because more reliable and uniform sizing
is obtained, since it is easier to optimize the amount
to be supplied when using a single-component size
according to the invention as compared with conventional
two-component sizes.
At present, the greatest advantage, as compared
with conventional rosin sizes, is considered to be
that the hydrophobing agent according to the invention
is very effective also at high pH values in such types
of paper as contain large amounts of calcium carbonate
as filler.
Another advantage of the invention is that the
hydrophobing agent consists of considerably less costly
raw materials than the commercially available synthetic
sizing agents. Resin acids and fatty acids are available
in practically unlimited quantities. From the technical
point of view, the novel hydrophobing agent is also
superior to synthetic sizing agents (e.g. alkyl ketene
dimers) for neutral or alkaline paper systems since
the hydrophobing agent according to the invention
is quick-setting and, hence, gives a low-wetting paper
already on the papermaking machine. Thus, the distur-
bances in production entailed by the use of other
synthetic sizing agents will not occur.
~ 33~8~3
Generally speaking, the invention resides in that a
polyaluminium salt, a non-saponified resin acid and/or
fatty acid, optionally in admixture with a melting point
lowering additive, such as paraffin, and preferably also
a cationic organic substance are mixed in water under
vigorous agitation, thus yielding an emulsion/dispersion
which consists of small cationic droplets in the order of
size of 0.05-50 ~m, most preferably 0.05-25 ~m.
Optimum effect and stability of the size is ob-
tained if the cationic organic substance is included
in the size itself. In certain applications, it is
however possible to add the single-component size
(i.e. resin acid/fatty acid and the particular poly-
aluminium salt) to the cationic organic substance
only in connection with the application to the organic
fibres. In papermaking, the cationic substance may
thus be separately added to the paper stock either
for the purpose of sizing or for any other purpose.
Thus, the sizing method according to the invention
can be combined with known papermaking processes where
a cationic organic substance is added to the stock,
for instance the processes according to European pa-
tent specification EP-Bl-41,056 and European published
patent application EP-Al-80,986.
The thus prepared dispersion/emulsion, especially
if it contains the cationic organic substance, is
so stable and highly concentrated that it can most
advantageously be delivered to the user in conventional
means of transportation.
~ ~s~9~ i~
The polyaluminium salts which have been found
the most useful for achieving the object of the inven-
tion are basic polyaluminium salts such as polyaluminium
sulphate or polyaluminium chloride. These salts are
distinguished by a high molar ratio of aluminium to
gegenion (>1) and by yielding in aqueous solution
polyaluminium ions having high charge, such as e.g.
A11304(0H)26(H20)10
The raw material for the hydrophobing agent accord-
ing to the invention may be pure resin acids, pure fatty
acids or combinations of resin acids or fatty acids, but
it is also possible to admix melting point lowering addi-
tives, such as paraffins.
When resin acid is used, a typical resin acid
composition is as follows:
abietic acid 40%
neoabietic acid 4%
pimaric acid 3%
isopimaric acid 6%
palustric acid 7%
balance 40%
When fatty acid is used and derives from tall
oil, the following composition is customary:
oleic acid 30%
linolenic acid 65%
other acids 5%.
In the invention it is possible to use a modified
resin acid which has been fortified by reactions with
3~ 13
substances commonly used in this context, such as
maleic anhydride, fumaric acid etc.
In the invention, it is important that the resin
acids and/or fatty acids used are in uncharged form
(non-saponified form), i.e. that pH should be kept
low, preferably below 5. At higher pH values, negatively
charged carboxylate groups are obtained, reducing
the cationic character of the emulsion/dispersion
droplets (the emulsion/dispersion being broken).
Suitable amounts of the different components
are 0.5-90% resin acid/fatty acid and 10-99.5% water.
A suitable weight ratio of resin acids/fatty
acids to aliminium in the dispersion is between 100:1
and 1:4, preferably 10:1 and 10:2.
The cationic organic compound included in the
aqueous phase may be a tenside, starch, guar gum,
carboxymethylcellulose, polyacrylamide, polyimine,
polyamine, polyamide amine, polyethylene imine or
polyacrylate. A suitable weight ratio of resin acids/
- fatty acids to the cationic organic compound is between
100:0.01 and 100:30.
The invention will be illustrated in more detail
hereinbelow in a number of Examples.
EXAMPLE 1
In this Example, a size emulsion was prepared
by mixing 500 g tall oil fatty acid (BEVACID 2 from
Bergvik Kemi, Soderhamn, Sweden) fortified with 5%
fumaric acid, with 2.49 g cationic tenside (hexadecyl-
trimethylammonium chloride from Riedel-de Haén AG,
* a Trade Mark 12
~3 ~3~s~3
Seelze-Hannover, West Germany) and 69.9 g ethanol.
This mixture was thereafter added under vigorous agi-
tation (agitator ULTRA-TURRAX from IKA-Werk, Stuten)
to a mixture consisting of 5.61 g cationic starch
having a nitrogen content of 0.4% (starch S-195 from
Raisio-SLR AB, Gothenburg, Sweden), 967.5 g polyalumi-
niu~ chl~ride ~A12(OH)5Cl.2H20 from Albright & Wilson,
Ltd., London, Al-content 25% by weight] in 4454 g
water. In the mixing process, the temperature was
25~C for both the fatty acid phase and the aqueous
phase.
The mixture was thereafter homogenized in a valve
homogenizer (Gualin Lab. 60, APV Schroder, Lubeck,
West Germany) at 350 bar gauge pressure. The pH of
the resulting emulsion was measured at room tempera-
ture and was 3.7. In microscope, it was found that
the prepared sizing agent had an emulsion droplet
size of about 1-2 ~m.
The resulting emulsion was stable to phase sepa-
ration for more than two months.
EXAMPLE 2
25 q of a mixture of 55% tall oil fatty acid
and 45% tall oil resin acid (special fraction from
distilling plant at Bergvik Kemi AB - the fraction
was fortified with I0% fumaric acid) was added in
the same way as in Example 1 to a mixture of 24 g
polyaluminium chloride (same as in Example 1) and
0.063 g cationic polyacrylamide ("PERCOL" 181 from
COM, Vastra Frolunda, Gothenburg) and 250 ml water.
* a Trade Mark 13
~ -- 3 33~9
~ , .
Otherwise, the preparation was performed in the same
manner as in Example 1, and the result was a stable
dispersion of small particle size and a pH of about
2.5.
EXAMPLE 3
In this Example, a stable dispersion was prepared
by adding 1.7 g unfortified tall oil resin acid ("BEVIROS
SG" from Bergvik Kemi AB, Soderhamn) to 16.7 g water
containing 0.02 g cationic tenside (hexadecyltrimethyl-
ammonium bromide from Riedel-de Haén AG, Seelze-Hannover,
West Germany) and 1.6 g polyaluminium chloride (same
as in Example 1).
The mixture was transferred to a 100 ml pressure
vessel and heated to 148~C on a heating plate under
magnetic agitation. After 30 minutes, heating was
interrupted and the dispersion was allowed to cool
slowly to room temperature. The pH of the resulting
product was 2.8.
EXAMPLE 4
To 50 g of a mixture of fatty acid/resin acid
(same fraction as used in Example 2) was added 0.13 g
cationic tenside (dissolved in 3.5 g ethanol). The
cationic tenside was the same as in Example 3.
The fatty acid/resin acid mixture was added to
148 g water containing 48.4 g polyaluminium chloride
(same as in previous Examples) and 0.25 g cationic
starch having a nitrogen content of 0.4%. Otherwise,
the method of preparation was the same as in Examples
1 and 2.
~ * a Trade Mark
~ ~ "~ 14
. j~ 5.
.~ ~
-- ~ 3 ~33~ll3
This experiment yielded a stable dispersion having
a pH of 2.5 and a slightly higher viscosity than the
dispersion in the previous Examples.
EXAMPLE 5
In this Example, 25 g fatty acid/resin acid (same
fraction as in Example 2) was added to 250 ml water
containing 0.6 g cationic guar gum (nitrogen content
1.5~, "GENDRIVE 162" from Henkel Company, USA) and
150 g polyaluminium sulphate (the polyaluminium sul-
phate had been obtained from Boliden Kemi AB, Helsingborg,
Sweden, and contained 15.5% aluminium and 65% sulphate,
i.e. the molar ratio of Al to SO4 was 0.9).
In other respects, the method of preparation
was the same as in the previous Examples. The pH of
the dispersion was 2.5. This experiment showed that
the fatty acid/resin acid could be combined with the
other components, i.e. so as to obtain a dispersion.
The stability of the dispersion to phase separation
was however lower (24 hours) than in the previous
Examples.
EXAMPLE 6
1.25 g cationic starch having a nitrogen content
of 0.40% and 4.86 g polyaluminium chloride (see pre-
vious Examples) was dissolved in 250 g water at 95~C.
25 g tall oil fatty acid (same as in Example 1)
was heated to 95~C and continuously added to the hot
aqueous solution, using the above-mentioned technique.
The resulting emulsion had a pH of 2.5 and con-
tained emulsion droplets of the order of 3-4 ~m.
* a Trade Mark 15
~33~843
The emulsion was found stable to phase separation
for 8 days.
~ EXAMPLE 7
In this experiment, a stable size emulsion was
prepared by adding 25 g tall oil fatty acid ("BEVACID 2")
to 250 g water containing 5.6 g cationic starch having
a nitrogen content of 0.40% and 29.2 g polyaluminium
chloride. Otherwise, the same conditions prevailed
as in Example 1. The pH of the resulting emulsion
was 2.8.
EXAMPLE 8
25 g of a special fraction of fatty acid/resin
acid (same product as in Example 2) was added in the
manner described in Example 1 to a solution consisting
of 58.3 g polyaluminium chloride (same as in Example 1)
and 216.7 ml water. The method of preparation was
otherwise carried out in accordance with Example 1,
yielding a stable emulsion/dispersion having a pH
of 2.8.
EXAMPLE 9
In this Example, 25 g of a mixture of fatty acid/
resin acid (same fraction as in Example 2) was added
to a solution of 58.3 g polyaluminium chloride (same
as in Example 1) and 91.7 g water, the same techni-
que being used as in Example 1. After cooling in a
water bath, 125 g of a 1% solution of cationic starch
(nitrogen content 0.40%) was admixed with the product
as above. The result was a stable emulsion/dispersion
having a pH of 2.8.
16
~ ~98~13
EXAMPLE 10
A paper stock of the following composition was
prepared:
70% fully bleached chemical pulp (60/40 birch
sulphate/pine sulphate)
30~ calcium carbonate ("Sjohasten" from Malmokrita,
Malmo, Sweden).
The birch and pine sulphates were milled together
in a laboratory hollander to beating degree 200 ml
CSF (Canadian Standard Freeness). The calcium car-
bonate (slurried in water) was added and the stock
was diluted to 0.5% dry solids content. The pH of
the stock was 8Ø
In the experiment, different amounts were added,
both of sizing agent according to Example 1 and of
a conventional rosin size ("T-size 7635" from Hercules
AB, Gothenburg") to different batches of the paper
stock.
In the experiments with the conventional rosin
size, 2% alum (calculated on dry pulp) was added in
a conventional manner before the addition of size.
The sizing agents were supplied in the form of
1% solutions and added to the 0.5% stock under agitation
(45 seconds). The stock was thereafter transferred
to a laboratory wire mould (Finnish hand mould) with
a 100 mesh wire. Sheet formation was performed according
to SCAN C 26:67 (grammage was 73 g/m ). The sheets
were dried overnight at 23~C and 50% relative humidity,
* a Trade Mark
17
., ~
'~ i
8 ~ 9
whereupon they were placed in a heating cabinet (30 mi-
nutes) at 120~C.
After conditioning (23~C, 50% relative humidity),
water absorbency was determined according to SCAN
P 12:64 (Cobb60).
Table I gives the results of the tests. The added
amounts of sizing agents (% by weight) relate to the
added amount (active content) calculated on dry stock.
It appears from Table I that the sizing agent accord-
ing to the invention gives fully satisfactory sizing
(Cobb60<25) despite high pH and large amounts of cal-
cium carbonate.
TABLE 1
Sizing agentAmount added (%) Cobb60 (g/m2)
Example 1 0.3 46
" 0.5 17
" 0.7 14
" 1.3 13
" 2.0 12
T-size 7635 0.3 95
" 0.7 74
" 1.3 44
2.0 35
18
l~3S~4~
EXAMPLE 11
A paper stock was prepared in the same manner
as in Example 10. The resulting stock had a pH of
7.3. Different sizing agents according to the inven-
tion were added to the stock.
Sheet forming and drying of the paper sheets
were carried out in the manner stated in Example 8.
Water absorption according to Cobb60 (SCAN P 12:64)
was determined. The results are given in Table 2.
TABLE 2
Water absorption according to Cobb60 (g/m2)
\ Addition %
Sizing \ 0 1.0 1.5 2.0
agent accord- \
ing to Example
2 113 45 38 23
3 113 83 69 40
4 113 21 16 14
113 67 57 42
EXAMPLE 12
In this experiment, use was made of a paper stock
from a magazine paper mill. The pulp consistency of
the stock was 3% and the pulp was milled to beating
degree 125 CSF. The composition of the pulp used was:
22% fully bleached chemical pulp
15% TMP (thermomechanical pulp)
35% groundwood pulp
28~ broke
19
~ 3 ~ 4 ~
To the stock was added 30% kaolin (C-clay from
ECC) calculated on dry fiber. The stock was diluted
to 0.5% concentation and pH was adjusted to 5Ø
Sizing agent prepared according to Example 3
was added in different amounts to the suspension of
fibers and filler. Sheets were formed according to
SCAN C 26:67 (grammage 73 g/m ).
In this experiment, the sheets were dried on
a drying cylinder at 85~C. The sheets were thereafter
placed in a drying oven (120~C) where they remained
for 30 minutes.
After conditioning (23~C, 50% relative humidity),
water absorbency was measured according to Cobb60.
The results of these measurements are given in Table 3.
TABLE 3
% sizing agent Cobb60
according to 2
Example 4 (g/m )
0 219
0.5 193
1.0 93
2.0 19
EXAMPLE 13
In this experiment, use was made of a paper pulp
having a dry solids content of 1.37% and a beating
degree of 200 ml CSF and consisting of 60% birch sul-
phate pulp and 40% pine sulphate pulp.
~ 3 3~84~
To the paper pulp was added 30% calcium carbonate
("Sjohasten" from Malmokrita) calculated on dry fiber.
pH was thereafter adjusted to 8.5. A sizing agent
prepared according to Example 1 was added to the stock
in different amounts. Sheets were thereafter formed
according to SCAN C 26:67 and had a grammage of 73 g/m2.
The sheets were dried and examined as described in
Example 10. Sizing was very satisfactory. The sizing
results are given in Table 4.
TABLE 4
Water absorption according to Cobb60 (g/m2)
\ ddition
Sizing \
agent \ 0% 0.3% 0.5% 1.0% 2.0%
According to
Example 1 103 58 27 15 12
EXAMPLE 14
In this experiment, use was made of the same
paper stock and the same procedure as in Example 10.
The hydrophobing agent was however a sizing agent
according to Example 8. It was added in different
amounts, 0.6% cationic starch (calculated on dry stock)
being added 15 seconds after the addition of size to
serve as external retention agent. The results of the
experiments appear from Table 5. It appears from the ex-
periments that the sizing agent according to Example 1
gave an improvement also in the absence of cationic
substance but that the improvement was more pronounced
when the cationic substance was added.
TABLE 5
Water absorption according to Cobb60
Sizing agent Addition Addition of cat-Cobb
of slze ionic starch
(%) (%) (g/m
According to
Example 8 0.3 0 83
" 0.5 0 65
" 1.0 0 50
" 2.0 0 46
According to
Example 8 0.3 0.6 76
. " 0.5 0.6 67
" 1.0 0.6 37
" 2.0 0.6 18
Zero test 0 0 99
EXAMPLE 15
In the experiments according to this Example,
use was made of a paper stock which had been prepared
in the manner described in Example 10. In sizing,
the same procedure was adopted as in Example lO, but
in this present Example use was instead made of a
sizing agent prepared in accordance with Example 9.
Fully satisfactory sizing was obtained also in this
experiment, the result of which appears from Table 6.
l~3~4~
TABLE 6
Water absorption according to Cobb60
Sizing agent Addition of size Cobb60 (g/m )
According to
Example 9 0.3 71
" 0.5 66
" 1.0 46
" 2.0 17
Zero test 0 99
EXAMPLE 16
As hydrophobic substance in this Example, use was
made of a mixture of 42 g tall oil rosin (BEVIROS SG
from Bergvik Kemi) and 18 g paraffin wax (melting point
58~C from Malmsten & Bergvall, Gothenburg). This hydro-
phobic substance was added under very vigorous agitation
(ULTRA TURRAX from IKA-Werk, Staufen) to a mixture con-
sisting of 3 g cationic starch having a nitrogen content
of 0.4%, 144.7 g polyaluminium chloride solution (KLOR-
HYDROL from Reheis Chemical Ltd., Dublin, Al-content
12.5% by weight) and 92.3 g water. At emulsification,
the temperature was 95~C for all chemicals included.
The emulsion was then homogenized for another
3 minutes at 10,000 rpm and thereafter cooled in a
water bath to room temperature.
The pH of the thus prepared product was 3.7 and
the particle size was about 1-2 ~m. The stability
was satisfactory for more than two months.
* a Trade Mark 23
4 3
For testing the sizing agent thus prepared, a
paper stock of the following composition was prepared:
80% fully bleached chemical pulp (60/40 birch sul-
phate/pine sulphate)
20% calcium carbonate ("Sjohasten" from Malmokrita).
The birch and pine sulphates were milled together in
a laboratory hollander to beating degree 200 ml CSF (Cana-
dian Standard Freeness). The calcium carbonate (slurried
in water) was added, and the stock was diluted to 0.5%
dry solids content. The pH of the stock was 8Ø
The sizing agents were added in the form of a
1% solution and added to the 0.5% stock under agitation
(45 seconds). The stock was thereafter transferred
to a laboratory wire mould (Finnish hand mould) with
a 100 mesh wire. Sheet formation was carried out ac-
cording to SCAN C 26:67 (grammage was 73 g/m ). The
sheets were dried overnight at 23~C and 50% relative
humidity, whereupon they were placed in a heating
cabinet (30 minutes) at 120~C.
After conditioning (23~C, 50% relative humidity),
water absorbency was determined according to SCAN
P 12:64 (Cobb60).
In Table 7, the results of the tests are given.
The added amounts of sizing agents (% by weight) relate
to the added amount (active content) calculated on
dry stock. It appears from Table 1 that the sizing
agent according to the invention yields fully satis-
factory sizing (Cobb60<25) despite high pH and large
amounts of calcium carbonate.
3 .3 3 8 ~ ~
TABLE 7
Sizing agentAmount added 1%)Cobb60 (g/m )
Example 16 0.3 71
" 0.5 64
" 0.8 22
" 1.0 18
" 2.0 15
EXAMPLE 17
Example 16 was repeated with the same constituents
but with the following amounts of the different consti-
tuents in the sizing agent emulsion:
48 g tall oil rosin
12 g paraffin wax
144.7 g polyaluminium chloride solution
3 g cationic starch
92.3 g water
The resulting emulsion had a pH of 3.7, a particle
size of about 1-2 ~m, and satisfactory stability for
more than two months.
The emulsion was thereafter used for sizing the
same paper stock as in Example 16, and the results
of this test are given in Table 8.
1 3 3 ~
TABLE 8
Sizing agentAmount added (%)Cobb60 (g/m )
Example 17 0.3 90
" 0.5 82
" 0.8 71
" 1.0 65
" 2.0 18
26
