Note: Descriptions are shown in the official language in which they were submitted.
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HYDROPHILIC COMB POLYURETHANE
FIELD OF THE INVENTION
The present invention relates to comb water soluble (hydrophilic)
polyurethanes containing polyoxyethylene side-chains.
The comb polyurethanes are characterized by having molecular weight higher
than 100,000 and by containing polyoxyethylene side-chains having each
molecular weight higher than 500 and ethylene oxide content from 80 to
99.5% by weight.
The present invention additionally relates to the use of the above comb
polyurethanes as deflocculant and water retention agents in paper coating
compositions.
BACKGROUND OF THE ART
Hydrophilic comb polyurethanes containing polyoxyethylene side-chains are
known and have been described in the patent literature.
EP 60,430 discloses a process for making a polyurethane having polyalkylene
oxide side-chains characterised in that the polyalkylene oxide used as
starting
alcohol has at least two free hydroxy groups separated by not more than 3
carbon atoms, which hydroxy groups react with diisocyanates.
The resulting polyurethanes may be used to stabilise or destabilise foams,
emulsions and dispersions. They may also be used with pigments and fillers.
However, there is no mention in EP 60,430 of polyurethanes bearing
polyoxyethylene side-chains having molecular weight higher 100,000, or of the
use of the polyurethanes in paper coating compositions.
WO 03/046038 describes a broad family of polyurethane dispersants
comprising from 35 to 90% by weight of poly(C2_4-alkylene oxide) based on the
total weight of the polyurethane polymer, wherein not less than 60% by weight
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of the poly(C2_C4-alkylene oxide) is poly(ethylene oxide) and at least 5% of
the
poly(C2_4-alkylene oxide) is incorporated in lateral chain; acid groups are
also
needed, but only when the polyurethane polymer contains from 35 to 45% by
weight poly(ethyleneoxide). Other optional components of the polyurethane are
compounds having at least two groups which reacts with isocyanates and
compounds acting as chain terminators. The number average molecular weight
of the polyurethane of WO 03/046038 is not less than 2,000 and preferably not
greater than 50,000. WO 03/046038 is silent about the possibility of using the
polyurethanes in paper coating compositions.
It is well known that the surface of printing paper sheets is commonly coated
with a paper coating formulation to improve the printability and to make it
smooth and glossy.
Paper coating compositions generally comprise fillers or pigments dispersed in
water, polymeric binders, rheology modifiers, water retention agents and
dispersing agents.
Dispersing agents are indispensable to reduce the viscosity in the presence of
the high solid contents which are typical of paper coating compositions and to
maintain a constant desired processing viscosity; examples of conventional
dispersing agents are complex phosphates, salts of polyphosphoric acid and
salts of polycarboxylic acids.
Water retention agents prevent dewatering of the coating composition upon
contact with the surface of the paper sheet; a typical water retention agent
for
paper coating composition is carboxymethyl cellulose.
Rheology modifiers are added to modulate the paper coating viscosity.
Binders are responsible for cohesion of the final coating and for its grafting
to
the paper sheet.
Some conventional paper coating additives are known to perform more than
one function; by way of example, carboxymethyl cellulose acts both as
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rheology modifier and water retention agent, polyvinyl alcohol acts as water
retention agent and optical brightness enhancer.
WO 01/96007, WO 2004/044022, WO 2004/041883 and WO 2007/069037
describe the use of polyacrylic anionic copolymers in the paper industry, for
making or coating paper; the polyacrylic anionic copolymers contain at least
one anionic ethylenically unsaturated monomer having monocarboxylic
functionality and at least one non-ionic ethylenically unsaturated monomer
having poly(C2_4-alkylene oxide) functionalities. They are said to be useful
as
dispersing and/or grinding agents, as agents for improving the optical
brightening activation, as water retention agents, as viscosity and gloss
enhancers.
Unfortunately, when the known ionic substances are used in aqueous
dispersions in accordance with the prior art, their effectiveness is dependent
on
the pH value of the dispersion.
It has now been found that specific hydrophilic comb polyurethanes are
suitable
as water retention agents and gloss enhancer for paper coating compositions;
the paper coating compositions of the invention are stable over a wide
viscosity
range irrespective of their pH value and impart good printability and gloss to
coated paper.
SUMMARY OF THE INVENTION
In one embodiment, the invention is a water soluble comb polyurethane
comprising a main chain (backbone) containing urethane and urea linkages
with multiple trifunctional branch points (branch points) from each of which a
polyoxyethylene side-chains emanates, the comb polyurethanes being
characterized by having molecular weight higher than 100,000, preferably from
300,000 to 3,000,000, and by containing polyoxyethylene side-chains having
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each molecular weight higher than 500, preferably from 2,000 to 20,000, and
ethylene oxide content from 80 to 99.9% by weight.
In another embodiment, the present invention is a paper coating composition
comprising a) from 30 to 80% by weight of an inorganic pigment; b) from 0.05
to 3.0 parts by weight each 100 parts by weight of pigment of the above
described comb polyurethane; c) at least 15% by weight of water.
In another embodiment, the present invention provides a water soluble comb
non-ionic polyurethane comprising a main chain containing urethane and urea
linkages with branch points from each of which linear polyoxyethylene side-
chains emanates, wherein the comb polyurethane has a molecular weight higher
than 100,000 and wherein the polyoxyethylene side-chains each have a
molecular weight higher than 500 and ethylene oxide content from 80 to 99.9%
by weight.
In another embodiment, the present invention provides paper coating
compositions comprising a) from 30 to 80% by weight of an inorganic pigment
comprising kaolins, calcium carbonate, talc, titanium dioxide, barium sulfate,
or
gypsum or any combination thereof; b) from 0.05 to 3.0 parts by weight each
100 parts by weight of pigment of at least one comb polyurethane as described
herein; c) at least 15% by weight of water, and having Brookfield viscosity
at
25 C and 100 rpm of less than 3,000 nnPa.s.
DETAILED DESCRIPTION
The polyoxyethylene side-chains of the comb polyurethane are distributed
along the backbone at intervals of less than 100, preferably of less than 50,
covalent bonds.
In the present text, with the expression "polyoxyethylene side-chains" we
mean side chains containing -(CH2CH20),- units with n29.
The main chain containing urethane and urea linkages has uniformly spaced
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branch points, whose distribution can be predicted from the molar ratios and
chemical nature of reactants and does not depend from the reaction conditions
or catalysts used. Therefore, the fine structure of the comb polyurethane can
be advantageously reproduced and possibly modulated as desired.
The polyurethane backbone shall be per se insoluble in water and preferably it
does not contain any internal or terminal polyoxyethylene chain.
The high molecular weight hydrophilic comb polyurethanes may be prepared by
any method known in the art.
The polyoxyethylene side-chains of the comb polyurethane are introduced by
reacting in one of the preparation steps an organic isocyanate group with at
least one compound having molecular weight higher than 500, preferably from
2,000 to 20,000, more preferably from 4000 to 6000, ethylene oxide content
from 80 to 99.9% by weight, preferably from 90 to 99.9% by weight, and
having one group which reacts with isocyanates.
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Comb polyurethanes having polyoxyethylene side-chains with molecular
weight from 2,000 to 20,000 and ethylene oxide content from 90 to 99.9% by
weight are preferred for use in paper coating compositions, because they
impart better water retention, with only slight loss on gloss values.
5 Any compound having molecular weight higher than 500, ethylene oxide
content from 80 to 99.9% by weight and having one group which reacts with
isocyanates may be used to introduce the polyoxyethylene side-chains in the
comb polyurethane.
Convenient examples of such compounds are C1-C4 poly(ethylene oxide)
monoalkyl ether, such as poly(ethylene oxide) monomethyl ether and
poly(ethylene oxide) monobutyl ether, poly(ethylene oxide) monomethyl ether
having molecular weight from 4,000 to 6,000 being the most preferred
compound.
The term molecular weight used in this text means the number average
molecular weight, when polymers are concerned.
The methods of preparation of the comb polyurethanes of the invention
comprise, as key intermediate, a bifunctional isocyanate containing
polyoxyethylene side-chains having each molecular weight higher than 500,
preferably from 2,000 to 20,000, and ethylene oxide content from 80 to 99.9%
by weight which is reacted with one or more compounds having molecular
weight from 34 to 300 and two groups which react with isocyanates, in order to
chain extend the backbone, to increase the molecular weight of the
bifunctional
isocyanate and to obtain a comb polyurethane having high molecular weight.
According to one preferred method of preparation (Method A), the comb
polyurethane is obtained by reacting in a first step about one mole of a
compound having molecular weight from 92 to 1,200 and having three groups
which react with isocyanates with about 3 moles of a diisocyanate (step al);
in
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a second step, the thus obtained trifunctional isocyanate is reacted with
equimolar amounts of one or more compounds having molecular weight higher
than 500, preferably from 2,000 to 20,000, ethylene oxide content from 80 to
99.9% by weight and having one group which reacts with isocyanates (step
a2); in a third step, the thus obtained bifunctional isocyanate is reacted
with
one or more compounds having molecular weight from 34 to 300 and having
two groups which react with isocyanates (step a3).
According to another preferred method of preparation (Method B) the comb
polyurethane is obtained by reacting in a first step a polyisocyanate with one
or
more compounds having molecular weight higher than 500, preferably from
2,000 to 20,000, ethylene oxide content from 80 to 99.9% by weight and
having one group which reacts with isocyanates (step bl) in order to obtain,
in
the average, a bifunctional isocyanate; in a second step, the thus obtained
isocyanate is reacted with one or more compounds having molecular weight
from 34 to 300 and having two groups which react with isocyanates (step b2).
According to still another preferred method of preparation (Method C) the comb
polyurethane is obtained by reacting in a first step a diisocyanate with
equimolar amounts of one or more compounds having molecular weight higher
than 500, preferably from 2,000 to 20,000, ethylene oxide content from 80 to
99.9% by weight and having one group which reacts with isocyanates (step
cl); in a second step, the thus obtained monofunctional isocyanate is reacted
with equimolar amounts of one or more compounds having molecular weight
from 34 to 300 and having at least one ¨NH- group which reacts with
isocyanates and at least two hydroxyl groups which react with isocyanates
(step c2); in a third step, the thus obtained compound having two groups
which react with isocyanates is reacted with diisocyanates in order to obtain
an
intermediate compound capped by two lateral isocyanate groups (step c3); in a
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fourth step, the thus obtained bifunctional isocyanate is reacted with one or
more compounds having molecular weight from 34 to 300 and having two
groups which react with isocyanates (step c4).
The compound of step al having molecular weight from 92 to 1,200 and having
three groups which react with isocyanates is preferably a trifunctional
alcohol.
Examples of utilizable trifunctional alcohols are glycerin, polypropylene
glycol
trio!, trimethylolpropane, trimethylolethane,
Any organic diisocyanate having molecular weight below 500 and average
¨NCO functionality from 2.0 to 2.1 may be used in step al and cl as the
diisocyanate.
Examples of useful diisocyanates are 1,6-hexamethylene diisocyanate (HDI),
tetramethylene diisocyanate, 1-
isocyanate-3-isocyanate-methy1-3,5,5-
trimethyl-cyclohexane (or isophoronediisocyanate) (IPDI), 4,4'-dicyclohexyl-
methanediisocyanate, 2,4- toluenediisocyanate either alone or in admixture
with 2,6-toluenediisocyanate (TDI), 4,4'-diphenyl-methanediisocyanate (MDI),
meta-tetramethylxilylenediisocyanate (TMXDI), 1,5-naphthalene diisocyanate,
and mixtures thereof; cycloaliphatic and aliphatic diisocyanate are preferred,
the most preferred being IPDI.
The compounds having molecular weight from 34 to 300 and two groups which
react with isocyanates used in steps a3, b2 and c4 are preferably diamines.
Examples of utilizable diamines are hydrazine, ethylenediamine, piperazine,
1,5-pentanediamine, 1,6-dihexanediamine,
isophoronediamine,
diethylenetriamine.
Steps a3, b2 and c4 are preferably carried out by dispersing the bifunctional
isocyanate in water and adding to the dispersion the diamine, possibly
dissolved in water.
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The compound having molecular weight from 34 to 300 of step c2 is preferably
diethanolamine.
Any organic polyisocyanates with average -NCO functionality from 2,4 to 3,8
(trifunctional isocyanate), and having molecular weight below 800 may be
used in step b1.
Examples of trifunctional isocyanates are the compounds obtained from
trimerization, biurethization, urethanization or allophanation of difunctional
isocyanates, such as those mentioned above, and mixtures thereof.
Useful trifunctional isocyanates are HDI biuret, HDI isocyanurate, IPDI
trimers
and the combination of the above trifunctional isocyanates with diisocyanates.
The preferred trifunctional isocyanates are the isocyanurate and biuret
obtained
from hexamethylenediisocyanate, for example HDI isocyanurate in
asymmetrical form, HDI biuret in low viscous form, and those obtained by the
combinations of IPDI trimers and HDI trimers.
For purpose of the present invention, in order to obtain the desired high
molecular weight comb polyurethane, it is preferred to minimize the quantity
of
diisocyanate that may be present together with the trifunctional isocyanates
during the step b1, as it is well known to person skilled in the art.
For the purpose of the present invention, the ratio between the equivalents of
isocyanate groups and the equivalent of groups which react with isocyanate
during the step c3 is between 1.1 and 2.3.
The water soluble comb polyurethanes are preferably non-ionic compounds,
devoid of acid groups, such as carboxylic and sulphonic acid groups.
In the comb polyurethane the total ethylene oxide content, i.e. the sum of the
-(CH2CH20)- units, is preferably higher than 50% by weight, more preferably
higher than 70% by weight.
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Suitable solvents may be used in the preparation steps, but it is also
possible
to perform all the preparation steps with the neat reactants, without the use
of
water or organic solvents.
The water soluble comb polyurethanes according to the invention are useful as
water retention agents, deflocculant and viscosity stabilizer for paper
coating
compositions and provide coated paper with excellent printability, brightness
and gloss.
The paper coating compositions of the invention comprise a) from 30 to 80%
by weight of inorganic pigment; b) from 0.05 to 3.0 parts by weight each 100
parts by weight of pigment of the above described comb polyurethane; c) at
least 15% by weight of water, and have Brookfield viscosity at 25 C and 100
rpm of less than 3,000 mPa.s, preferably from 500 to 2,000 mPa.s.
The paper coating compositions according to the present invention also
comprise from 0.01 to 3% by weight of a dispersing agent, usually an anionic
un-crosslinked polyacrylatederivative, such as sodium polyacrylate, having
molecular weight from 5,000 to 40,000, because the comb polyurethane does
not act per se as pigment dispersant; the compositions may also contain a
specific rheologly modifier.
Typical useful rheology modifiers are carboxymethyl cellulose, hydroxypropyl
guar, hydroxypropylmethyl cellulose, xanthan, ASA polymers (i.e. "Alkali
Swellable Acrylic" polymers).
Dispersing agents, which are common ingredients of paper coating
compositions, are not generally able to prevent the flocculation of the finest
particles, especially when the paper coating composition is being applied on
the
paper sheet, i.e. under high stress conditions, and the particles flocculation
is
detrimental to smoothness and gloss of the resulting coated paper.
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The comb polyurethanes of the invention are particularly effective as
deflocculants, avoiding the formation of clusters of fine particles, which may
tend to settle.
The inorganic pigments of the paper coating compositions, preferably having
5 from 40 to 90% of the particles finer than 2 microns, are those normally
employed in the coating of paper, and particularly kaolin, calcium carbonate,
talc, titanium dioxide, barium sulfate, gypsum or mixtures thereof.
The paper coating compositions of the invention normally also comprise from 1
to 15% by weight of a binder, preferably a polymeric acrylic binder.
10 Among the polymeric acrylic binder preferred for the realisation of the
invention
we cite the polymers of acrylic or methacrylic acid esters, the copolymers of
acrylic ester monomers and vinyl acetate, styrene, butadiene or mixture
thereof.
Other conventional additives, such as defoaming agents, biocides, optical
brighteners, may be present in the paper coating compositions.
Another advantageous characteristic of the polyurethanes of the invention is
the fact that they act as rheology and water retention buffers over different
batches of industrial paper coating compositions having same recipe; this
means that, in the industrial coating process, the usual deviations from the
theoretical amounts of paper coating ingredients does not affect the rheology
and water retention
characteristics.
EXAMPLES
In the examples the following materials were used:
TRIOL1: polypropylene glycol trio!, molecular weight 1000 g/mol, Voranol CP
1055, from Dow Chemical Company
ETHOXY1: butanol polyethoxylated, molecular weight 3000 g/mol
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ETHOXY2: methanol polyethoxylated, molecular weight 5000 g/mol
ETHOXY3: butanol polyethoxylated, molecular weight 5000 g/mol
ETHOXY4: methanol polyethoxylated, molecular weight 750 g/mol
DIISOCYANATE1: isophoronediisocyanate, molecular weight 222.3 g/mol,
Desmodur I from Bayer Material Science.
TRIISOCYANATE1: hexamethylene diisocyanate trimer, NCO content 24,0%,
NCO functionality 3,1, Desmodur XP2410 from Bayer Material Science.
AMINE1: isophorone diamine, molecular weight 170.3 g/mol, from Sigma
Aldrich
AMINE2: diethanolamine, molecular weight 105,14 g/mol, from Sigma Aldrich
AMINE3: ethylendiamine, molecular weight 60,10 g/mol, from Sigma Aldrich
AMINE4: 24% hydrazine hydrate solution, molecular weight 32.3 g/mol, from
Sigma Aldrich.
EXAMPLE I
Preparation of a comb polyurethane with Method A
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 100.0 g of
TRIOL1 and 300.0 g of ETHOXY1. The mixture was heated under stirring
condition to 85 C and 0.15 g of 85% phosphoric acid were added. At 85 C 69.0
g of DIISOCYANATE1 were charged to the homogeneous mixture, under
stirring; after 20 minutes 0.3 g of dibutiltindilaurate (DBTL) were added. The
reaction temperature was kept at 85 C until the titrimetric determination of
the
free -NCO groups still present gave a calculated value of 1,7% (value
determined in this example as well as in the other examples according to the
standard method ASTM D2572),
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300 g of the obtained product were dispersed by vigorous stirring into 890 g
of
water cooled at 18 C. After 20 minutes 9.7 g of AMINE1 dissolved in 39.3 g of
water were dropped in.
The obtained product had 25.55% solid content, viscosity 48 mPa.s (measured
by Brookfield viscometer at 20 rpm) and pH 6.5.
EXAMPLE II
Preparation of a comb polyurethane with Method A
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 50.0 g of
TRIOL1 and 250.0 g of ETHOXY2. The mixture was heated under stirring to
85 C and 0.11 g of 85% phosphoric acid were added . At 85 C, 34.5 g of
DIISOCYANATE1 were charged to the homogeneous mixture under stirring
condition; after 20 minutes 0.3 g of dibutiltindilaurate (DBTL) were added.
The
reaction temperature was kept at 85 C until the titrimetric determination of
the
free -NCO groups still present gave a calculated value of 1.26%.
300 g of the obtained product were dispersed by vigorous stirring into 893.1 g
of water cooled at 18 C. After 20 minutes 6.9 g of AMINE1 dissolved in 27.4 g
of water were dropped in.
The obtained product had solid content 26.15%, viscosity 62 mPa.s (measured
by Brookfield viscometer at 20 rpm) and pH 6.4.
EXAMPLE III
Preparation of a comb polyurethane with Method B
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 300.0 g of
ETHOXY1 and 0.11 g of 85% phosphoric acid.
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The mixture was heated under stirring condition to 85 C and 56.6 g of
TRIISOCYANATE1 were charged; after 20 minutes 0.3 g of dibutiltindilaurate
(DBTL) were added.
The reaction temperature was kept at 85 C until the titrimetric determination
of the free
-NCO groups still present gave a calculated value of 2.5%.
300 g of the obtained product were dispersed by vigorous stirring into 862.6 g
of water cooled at 18 C.
After 20 minutes 12.8 g of AMINE1 dissolved in 51.5 g of water were dropped
in.
The obtained product had solid content 25.98%, viscosity 196 mPa.s
(measured by Brookfield viscometer at 20 rpm) and pH 6.6.
EXAMPLE IV
Preparation of a comb polyurethane with Method B
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 274.5 g of
ETHOXY 2 and 0.11 g of 85% phosphoric acid. The mixture was heated under
stirring to 85 C and 31.1 g of TRIISOCYANATE1 were charged; after 20
minutes 0.3 g of dibutiltindilaurate (DBTL) were added.
The reaction temperature was kept at 85 C until the titrimetric determination
of the free -NCO groups still present gave a calculated value of 1.6%.
275 g of the obtained product were dispersed by vigorous stirring into 795.3 g
of water cooled at 18 C.
After 20 minutes 7.6 g of AMINE1 dissolved in 30.2 g of water were dropped in.
The obtained product had solid content 25.51%, viscosity 246 mPa.s
(measured by Brookfield viscometer at 20 rpm) and pH 5.5.
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EXAMPLE V
Preparation of a comb polyurethane with Method B
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 300.0 g of
ETHOXY3 and 0.11 g of 85% phosphoric acid. The mixture was heated under
stirring to 85 C and 22.0 g of TRIISOCYANATE1 and 10.1 g of DIISOCYANATE1
were charged; after 20 minutes 0.3 g of dibutiltindilaurate (DBTL) were added.
The reaction temperature was kept at 85 C until the titrimetric determination
of the free -NCO groups still present gave a calculated value of 1.8%.
280 g of the obtained product was dispersed by vigorous stirring into 826.4 g
of water cooled at 18 C.
After 20 minutes 9.4 g of AMINE4 dissolved in 9.8 g of water were dropped in.
The obtained product had solid content 26.07%, viscosity 412 mPa.s
(measured by Brookfield viscometer at 20 rpm) and pH 6.8.
EXAMPLE VI
Preparation of a comb polyurethane with Method B
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 300.0 g of
ETHOXY3 and 0.11 g of 85% phosphoric acid. The mixture was heated under
stirring to 85 C and 22.0 g of TRIISOCYANATE1 and 10.1 g of DIISOCYANATE1
were charged; after 20 minutes 0.3 g of dibutiltindilaurate (DBTL) were added.
The reaction temperature was kept at 85 C until the titrimetric determination
of the free -NCO groups still present gave a calculated value of 1.8%.
280 g of the obtained product were dispersed by vigorous stirring into 838.1 g
of water cooled at 18 C.
After 20 minutes 2.7 g of AMINE3 dissolved in 10.0 g of water were dropped in.
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The obtained product had solid content 25.84%, viscosity 256 mPa.s
(measured by Brookfield viscometer at 20 rpm) and pH 6.8.
EXAMPLE VII
Preparation of a comb polyurethane with Method C
5 A reaction vessel, equipped with internal thermometer, stirrer and
cooler, was
filled, under nitrogen atmosphere and at room temperature, with 300.0 g of
ETHOXY2 and 0.11 g of 85% phosphoric acid. The mixture was heated under
stirring to 85 C and 15.3 g of DIISOCYANATE1 were charged; after 10 minutes
0.3 g of dibutiltindilaurate (DBTL) were added. The reaction temperature was
10 brought to 85 C until the titrimetric determination of the free -NCO
groups still
present gave a calculated value of 0.9%. The mixture was then cooled to 55 C
and 6.6 of AMINE2 dissolved in 6.6 g of N-methylpyrrolidone were charged
dropwise. After 20 minutes the titrimetric determination of the free -NCO
groups gave a calculated value of 0.0%. The reaction temperature was then
15 brought to 85 C and 28.5 g of DIISOCYANATE1 was charged and it was
reacted
until the titrimetric determination of the free -NCO groups gave a calculated
value of 1.5%.
300 g of the obtained product were dispersed by vigorous stirring into 898.0 g
of water cooled at 18 C. After 20 minutes 2.9 g of AMINE3 dissolved in 10.7 g
of water were dropped.
The obtained product had solid content 24.99%, viscosity 194 mPa.s
(measured by Brookfield viscometer at 20 rpm) and pH 6.3.
EXAMPLE VIII
Preparation of a comb polyurethane with Method B
A reaction vessel, equipped with internal thermometer, stirrer and cooler, was
filled, under nitrogen atmosphere and at room temperature, with 300.0 g of
ETHOXY4 and 0.11 g of 85% phosphoric acid. The mixture was heated under
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stirring to 85 C and 226.2 g of TRIISOCYANATE1 were charged; after 10
minute 0.3 g of dibutiltindilaurate (DBTL) were added. The reaction
temperature was kept at 85 C until the titrimetric determination of the free -
NCO groups still present gave a calculated value of 5.9%. 470 g of the
obtained
product was dispersed by vigorous stirring into 1360 g of water cooled at 18
C.
After 20 minutes 16.7 g of AMINE3 dissolved in 62.1 g of water were dropped
in.
The obtained product had solid content 25.1%.
Application Examples
Paper coating compositions based on 100 /o carbonate (HydrocarbTM 90, from
Omya, CH) were prepared using the comb polyurethanes from Examples
and with a water retention agent of the prior art.
The compositions of the paper coating compositions are reported in Table 1;
the amounts of the ingredients are parts by weights.
The paper coating compositions were characterized by performing the following
measurements:
= pH
= Brookfield@ viscosity, 100 rpm
= Dry matter
= Water retention -Tappi Method T710
The data obtained are also reported in Table 1.
The paper coating compositions were applied (13 g/m2) on offset sheets (80
g/m2); the sheets were conditioned for 24h at 21 C and 50% r.h. and
calendared (cylinders temperature 55 C, pressure 67.5 Kg/cm; 4 nips).
Brightness and gloss were measured and are reported in Table 2.
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Table 1
PAPER COATING . . . . . : : - . ...
- - - ..:..... .. ....-. -....,..,
1 - - - 2 3 . 4 =-= :=
5 == 6 ;....7;=.=.= -- 8.. =.: ::..9'2..
COMPOSITIONS: .. ..::... .. =::::
HYDROCARB 90 100 100 100 100 100 100 100 100 100
Dow LATEX 9351) 10 10 10 10 10 10 10 10
10
RE TAN A2)
0.045 0.045 0.045 0.045 0.045 0.045 0.045 0.045 0.045
DEFOMEX 1083) 0.1 0.1 0.1 0.1 0.1 0.1 0.1
0.1 0.1
TINOPALTm ABP-Z4) 0.8 0.8 0.8 0.8 0.8 0.8 0.8
0.8 0.8
Ex. 1 0.45 / / / / / / / /
Ex. 2 / 0.45 / / / / / / /
Ex. 3 / / 0.45 / / / / / /
Ex. 4 / / / 0.45 / / / / /
Ex. 5 / / / / 0.45 / / / /
Ex. 6 / / / / / 0.45 / / /
Ex. 7 / / / / / / 0.45 / /
Ex. 8 / / / / / / / 0.45 /
Viscolam GP375) / / / / / / / /
0.15
CHARACTERISTICS- ===:::::.0-'. ..- .':-""'''''.
...:.:=:'=,0'... ' - '=::" =-===== ......V:'=!===:':::====:'::':,':::::iF'
..: ...;=7';''':' .:=: 7:: ):*'''.:...:: :: ;.......:
OFTHE-pApeR-
COATING . - . - i. . if. .:.. :...- ...,......
..: .. ... . . .:..-.. - : := ..:.;...; ...::::: : ..:
..... - .....:. .. .: .:-
COMPOSITIONS -:.... =''siCi; - = =L -=- Vi:' . '
===== = = ' .f=:'=:=: =-="= . = -
Dry matter (cY0) 70.32 70.40 70.18 70.16 69.95 69.95 69.97 70.21
70.18
pH 8.85 9.02 8.85 8.91 8.97 9.08 9.06 8.87 8.95
Viscosity (mPa*s) 550 655 570 650 600 770 650 450 960
Water retention
150 140 155 145 130 145 140 165 112
1) Binder, styrene butadiene latex (Dow Chemical Co. US)
2) Dispersant, sodium polyacrylate (Lambert' SpA, IT)
3) Defoaming agent, (Lamberti SpA, IT)
4) Optical brightener (CIBA, CH)
5) ASE Thickener from Lamberti SpA
6) comparative
CA 02755322 2011-09-12
WO 2010/106022 PCT/EP2010/053300
18
Table 2
PAPER COATING
Brightness1) 2)
Gloss @ 75
COMPOSITION :
1 100.8 72.5
2 100.6 72.1
3 101.1 72.8
4 100.5 72.0
100.3 72.4
6 100.4 72.7
7 100.9 72.6
8 100.6 75.2
93) 99.2 65.8
5 1) Brightness, Tappi Method T452
2) Specular Gloss at 75 , Tappi Method T480
3) comparative
