U.S. patent application number 14/237391 was filed with the patent office on 2014-06-19 for aqueous compositions for whitening and shading in coating applications.
The applicant listed for this patent is Clariant International Ltd.. Invention is credited to David Atkinson, Andrew Clive Jackson, Cedric Klein, Frederic Reveaud.
Application Number | 20140171560 14/237391 |
Document ID | / |
Family ID | 46634106 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140171560 |
Kind Code |
A1 |
Klein; Cedric ; et
al. |
June 19, 2014 |
AQUEOUS COMPOSITIONS FOR WHITENING AND SHADING IN COATING
APPLICATIONS
Abstract
The instant invention relates to aqueous coating compositions
for optical brightening and shading of substrates.
Inventors: |
Klein; Cedric; (Habsheim,
FR) ; Reveaud; Frederic; (Mulhouse, FR) ;
Atkinson; David; (Arlesheim, CH) ; Jackson; Andrew
Clive; (Muenchenstein, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Clariant International Ltd. |
Muttenz |
|
CH |
|
|
Family ID: |
46634106 |
Appl. No.: |
14/237391 |
Filed: |
August 4, 2012 |
PCT Filed: |
August 4, 2012 |
PCT NO: |
PCT/EP2012/003348 |
371 Date: |
February 6, 2014 |
Current U.S.
Class: |
524/100 |
Current CPC
Class: |
D21H 21/28 20130101;
D21H 21/30 20130101; D21H 21/18 20130101; C09B 23/148 20130101;
D21H 17/67 20130101 |
Class at
Publication: |
524/100 |
International
Class: |
D21H 21/28 20060101
D21H021/28 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2011 |
EP |
11006601.6 |
Claims
1. An aqueous coating composition for optical brightening and
shading of a substrate, comprising (a) at least one optical
brightener of formula (I) ##STR00009## in which the anionic charge
on the brightener is balanced by a cationic charge comprising one
or more identical or different cations selected from the group
consisting of hydrogen, an alkali metal cation, alkaline earth
metal, ammonium, ammonium which is mono-, di-, tri- or
tetrasubstituted by a C.sub.1-C.sub.4 linear or branched alkyl
radical, ammonium which is mono-, di-, tri- or tetrasubstituted by
a C.sub.1-C.sub.4 linear or branched hydroxyalkyl radical, ammonium
which is, di-, tri- or tetrasubstituted by a mixture of
C.sub.1-C.sub.4 linear or branched alkylradical and linear or
branched hydroxyalkyl radical or mixtures thereof, R.sub.1 and
R.sub.1 may be the same or different, and each is hydrogen,
C.sub.1-C.sub.4 linear or branched alkyl, C.sub.2-C.sub.4 linear or
branched hydroxyalkyl, CH.sub.2CO.sub.2, CH.sub.2CH.sub.2CONH.sub.2
or CH.sub.2CH.sub.2CN, R.sub.2 and R.sub.2 may be the same or
different, and each is C.sub.1-C.sub.4 linear or branched alkyl,
C.sub.2-C.sub.4 linear or branched hydroxyalkyl, CH.sub.2CO.sub.2,
CH(CO.sub.2)CH.sub.2CO.sub.2, CH(CO.sub.2)CH.sub.2CH.sub.2CO.sub.2,
CH.sub.2CH.sub.2SO.sub.3, CH.sub.2CH.sub.2CO.sub.2,
CH.sub.2CH(CH.sub.3)CO.sub.2, benzyl, or R.sub.1 and R.sub.2 and/or
R.sub.1 and R.sub.2, together with the neighboring nitrogen atom
signify a morpholine ring and p is 1 or 2, (b) at least one shading
dye of formula (II) ##STR00010## in which R.sub.3 signifies H,
methyl or ethyl, R.sub.4 signifies paramethoxyphenyl, methyl or
ethyl, M signifies a cation selected from the group consisting of
hydrogen, an alkali metal cation, alkaline earth metal, ammonium,
ammonium which is mono-, di-, tri- or tetrasubstituted by a
C.sub.1-C.sub.4 linear or branched alkyl radical, ammonium which is
mono-, di-, tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or
branched hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures thereof, (c) at least one white pigment, (d) at least one
primary binder, (e) optionally one or more secondary binders and
(f) water.
2. Aqueous coating composition according to claim 1, wherein in a
compound of formula (I) for which p is 1, the CO.sub.2 group is in
the 2 or 4-position of the phenyl ring.
3. Aqueous coating composition according to claim 1, wherein in a
compound of formula (1) the anionic charge on the brightener is
balanced by a cationic charge composed of one or more identical or
different cations selected from the group consisting of hydrogen,
an alkali metal cation, alkaline earth metal, ammonium which is
mono-, di-, tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or
branched hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures thereof, R.sub.1 and R.sub.1 may be the same or different,
and each is hydrogen, C.sub.1-C.sub.4 linear or branched alkyl,
C.sub.2-C.sub.4 linear or branched hydroxyalkyl, CH.sub.2CO.sub.2,
CH.sub.2CH.sub.2CONH.sub.2 or CH.sub.2CH.sub.2CN, R.sub.2 and
R.sub.2 may be the same or different, and each is C.sub.1-C.sub.4
linear or branched alkyl, C.sub.2-C.sub.4 linear or branched
hydroxyalkyl, CH.sub.2C0.sub.2, CH(CO.sub.2)CH.sub.2CO.sub.2 or
CH.sub.2CH.sub.2S0.sub.3 and P is 1 or 2.
4. An aqueous coating composition according to claim 1, wherein in
compounds of formula (I), the anionic charge on the brightener is
balanced by a cationic charge comprising one or more identical or
different cations selected from the group consisting of Li.sup.+,
Na.sup.+, K.sup.+, Ca.sup.2+, Mg.sup.+, ammonium which is mono-,
di-, tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or
branched hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures thereof, R.sub.1 and R.sub.1 may be the same or different,
and each is hydrogen, methyl, ethyl, propyl, .alpha.-methylpropyl,
.beta.-methylpropyl, .beta.-hydroxyethyl, .beta.-hydroxypropyl,
CH.sub.2CO.sub.2, CH.sub.2CH.sub.2CONH.sub.2 or CH.sub.2CH.sub.2CN,
R.sub.2 and R.sub.2 may be the same or different, and each is
methyl, ethyl, propyl, .alpha.-methylpropyl, .beta.-methylpropyl,
.beta.-hydroxyethyl, .beta.-hydroxypropyl, CH.sub.2CO.sub.2,
CH(CO.sub.2)CH.sub.2CO.sub.2 or CH.sub.2CH.sub.2S0.sub.3 and p is 1
or 2.
5. Aqueous coating composition according to claim 1, wherein in a
compound of formula (I), the anionic charge on the brightener is
balanced by a cationic charge comprising one or more identical or
different cations selected from the group consisting of Na.sup.t,
K.sup.t, triethanolammonium, N-hydroxyethyl-N,Ndimethylammonium,
N-hydroxyethyl-N,N-diethylammonium or mixtures thereof, R.sub.1 and
R.sub.1 may be the same or different, and each is hydrogen, methyl,
ethyl, propyl, .beta.-hydroxyethyl, .beta.-hydroxypropyl,
CH.sub.2CO.sub.2, CH.sub.2CH.sub.2CONH.sub.2 or CH.sub.2CH.sub.2CN,
R.sub.2 and R.sub.2 may be the same or different, and each is
ethyl, propyl, hydroxyethyl, .beta.-hydroxypropyl,
CH.sub.2CO.sub.2, CH(CO.sub.2)CH.sub.2CO.sub.2 or
CH.sub.2CH.sub.2SO.sub.3 and p is 1.
6. Aqueous coating composition according to claim 1, wherein the
compound of formula (I) is present in an amount of from 0.01 to 5%
by weight, % by weight being based on the total weight of said
white pigment.
7. Aqueous coating composition according to claim 1, wherein in a
compound of formula (II) R.sub.3 signifies H, methyl or ethyl,
R.sub.4 signifies paramethoxyphenyl, methyl or ethyl, M signifies a
cation selected from the group consisting of hydrogen, an alkali
metal cation, alkaline earth metal, ammonium which is mono-, di-,
tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures thereof.
8. Aqueous coating composition according to claim 1, wherein in a
compound of formula (II) R.sub.3 signifies methyl or ethyl, R.sub.4
signifies methyl or ethyl, M signifies a cation selected from the
group consisting of Li.sup.+, Na.sup.+, K.sup.+, K.sup.+, 1/2
Ca.sup.2+, 1/2 Mg.sup.2+, ammonium which is mono-, di-, tri- or
tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures thereof.
9. Aqueous coating composition according to claim 1, wherein in a
compound of formula (II) R.sub.3 signifies methyl or ethyl, R.sub.4
signifies methyl or ethyl, M signifies a cation selected from the
group consisting of Na.sup.+, K.sup.+, triethanolammonium,
N-hydroxyethyl-N,N-dimethylammonium,
N-hydroxyethyl-N,N-diethylammonium or mixtures thereof.
10. Aqueous coating composition according to claim 1, wherein the
compound of formula (II) is used in an amount from 0.00001 to 0.05%
by weight, the % by weight being based on the total weight of said
white pigment.
11. Aqueous coating composition according to claim 1, wherein the
coating composition comprises from 10 to 70% by weight of white
pigment, the % by weight being based on the total weight of the
coating composition.
12. Aqueous coating composition according to claim 11, wherein the
white pigment comprises an inorganic pigment.
13. Aqueous coating composition according to at least claim 11,
wherein the binder comprises a single binder or of a mixture of
primary and/or secondary binders.
14. Aqueous coating composition according to claim 13, wherein the
single or primary binder is used in an amount in a range of from 2
to 25% by weight, the % by weight being based on the total weight
of white pigment.
15. Aqueous coating composition according to claim 13, wherein
polyvinyl alcohol is used as secondary binder, which has a degree
of hydrolysis greater than or equal to 60% and a Brookfield
viscosity of from 2 to 80 mPas (4% aqueous solution at 20.degree.
C.).
16. Aqueous coating composition according to claim 13, wherein the
secondary binder is used in an amount in a range of from 0.1 to 20%
by weight, the % by weight being based on the total weight of white
pigment.
17. Aqueous coating composition according to claim 1, wherein the
pH value of the coating composition is in a range of from 5 to
13.
18. An aqueous coating composition according to claim 1, capable of
being used for optical brightening and tinting of a paper
substrate.
19. An aqueous coating composition according to claim 18, capable
of being used as a preformed aqueous solution, and the
concentration of compound of formula (I) in water is optionally
from 1 to 80% by weight, the % by weight being based on the total
weight of the preformed aqueous solution comprising the compound of
formula (I).
20. An aqueous coating composition according to claim 19, wherein
in the preformed aqueous solution, the concentration of compound of
formula (II) in water is optionally of from 0.001 to 30% by weight,
the % by weight being based on the total weight of the preformed
aqueous solution comprising the compound of formula (II).
21. An aqueous coating composition according to claim 19, wherein
in the preformed aqueous solution, the concentration of secondary
binders in water is from 1 to 50% by weight, the % by weight being
based on the total weight of the preformed aqueous solution
comprising the secondary binders.
Description
[0001] The instant invention relates to aqueous coating
compositions comprising derivatives of diaminostilbene optical
brightener, shading dyes, white pigments, primary binders, and
optionally secondary binders which can be used to provide coated
substrates of high whiteness and brightness.
BACKGROUND OF THE INVENTION
[0002] It is well known that the whiteness and thereby the
attractiveness of coated papers can be improved by the addition of
optical brighteners and shading dyes to the coating
composition.
[0003] WO 0218705 A1 however teaches that the use of shading dyes,
while having a positive effect on whiteness, has a negative impact
on brightness. The solution to this problem is to add additional
optical brightener, the advantage claimed in WO 0218705 A1 being
characterized by the use of a mixture comprising at least one
direct dye (exemplified by C.I. Direct Violet 35) and at least one
optical brightener.
[0004] In order to satisfy the demand for coated papers of higher
whiteness and brightness, there is a need for more efficient
shading compositions.
[0005] Surprisingly, we have now discovered shading dyes which have
a strongly positive effect on whiteness while having little or no
effect on brightness, and which can be used in coating compositions
comprising optical brighteners, white pigments, primary binders,
and optionally secondary binders in order to enable the papermaker
to reach high levels of whiteness and brightness.
[0006] Therefore, the goal of the present invention is to provide
aqueous coated compositions containing derivatives of
diaminostilbene optical brightener, certain shading dyes, white
pigments, primary binders, and optionally secondary binders, which
afford enhanced high whiteness levels while avoiding the
disadvantages characterized by the use of shading dyes (loss of
brightness) or pigments (lower whiteness build) recognized as being
state-of-the-art.
DESCRIPTION OF THE INVENTION
[0007] The present invention therefore provides aqueous coating
compositions for optical brightening and shading of substrates,
preferably paper, comprising
(a) at least one optical brightener of formula (I)
##STR00001##
in which [0008] the anionic charge on the brightener is balanced by
a cationic charge composed of one or more identical or different
cations selected from the group consisting of hydrogen, an alkali
metal cation, alkaline earth metal, ammonium, ammonium which is
mono-, di-, tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or
branched alkyl radical, ammonium which is mono-, di-, tri- or
tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures of said compounds, [0009] R.sub.1 and R.sub.1' may be the
same or different, and each is hydrogen, C.sub.1-C.sub.4 linear or
branched alkyl, C.sub.2-C.sub.4 linear or branched hydroxyalkyl,
CH.sub.2CO.sub.2.sup.-, CH.sub.2CH.sub.2CONH.sub.2 or
CH.sub.2CH.sub.2CN, [0010] R.sub.2 and R.sub.2' may be the same or
different, and each is C.sub.1-C.sub.4 linear or branched alkyl,
C.sub.2-C.sub.4 linear or branched hydroxyalkyl,
CH.sub.2CO.sub.2.sup.-, CH(CO.sub.2.sup.-)CH.sub.2CO.sub.2.sup.-,
CH(CO.sub.2.sup.-)CH.sub.2CH.sub.2CO.sub.2.sup.-,
CH.sub.2CH.sub.2SO.sub.3.sup.-, CH.sub.2CH.sub.2CO.sub.2.sup.-,
CH.sub.2CH(CH.sub.3)CO.sub.2.sup.-, benzyl, or [0011] R.sub.1 and
R.sub.2 and/or R.sub.1' and R.sub.2', together with the neighboring
nitrogen atom signify a morpholine ring and [0012] p is 1 or 2, (b)
at least one shading dye of formula (II)
##STR00002##
[0012] in which [0013] R.sub.3 signifies H, methyl or ethyl, [0014]
R.sub.4 signifies paramethoxyphenyl, methyl or ethyl, [0015] M
signifies a cation selected from the group consisting of hydrogen,
an alkali metal cation, alkaline earth metal, ammonium, ammonium
which is mono-, di-, tri- or tetrasubstituted by a C.sub.1-C.sub.4
linear or branched alkyl radical, ammonium which is mono-, di-,
tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures of said compounds, (c) at least one white pigment, (d) at
least one primary binder, (e) optionally one or more secondary
binders and (f) water.
[0016] In compounds of formula (I) for which p is 1, the
CO.sub.2.sup.- group is preferably in the 2 or 4-position of the
phenyl ring.
[0017] Preferred compounds of formula (I) are those in which
the anionic charge on the brightener is balanced by a cationic
charge composed of one or more identical or different cations
selected from the group consisting of hydrogen, an alkali metal
cation, alkaline earth metal, ammonium which is mono-, di-, tri- or
tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures of said compounds, [0018] R.sub.1 and R.sub.1' may be the
same or different, and each is hydrogen, C.sub.1-C.sub.4 linear or
branched alkyl, C.sub.2-C.sub.4 linear or branched hydroxyalkyl,
CH.sub.2CO.sub.2.sup.-, CH.sub.2CH.sub.2CONH.sub.2 or
CH.sub.2CH.sub.2CN, [0019] R.sub.2 and R.sub.2' may be the same or
different, and each is C.sub.1-C.sub.4 linear or branched alkyl,
C.sub.2-C.sub.4 linear or branched hydroxyalkyl, CH.sub.2CO.sub.2,
CH(CO.sub.2.sup.-)CH.sub.2CO.sub.2.sup.- or
CH.sub.2CH.sub.2SO.sub.3.sup.- and is 1 or 2.
[0020] More preferred compounds of formula (I) are those in
which
the anionic charge on the brightener is balanced by a cationic
charge composed of one or more identical or different cations
selected from the group consisting of Li.sup.+, Na.sup.+, K.sup.+,
Ca.sup.2+, Mg.sup.2+, ammonium which is mono-, di-, tri- or
tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures of said compounds, [0021] R.sub.1 and R.sub.1' may be the
same or different, and each is hydrogen, methyl, ethyl, propyl,
.alpha.-methylpropyl, .beta.-methylpropyl, .beta.-hydroxyethyl,
.beta.-hydroxypropyl, CH.sub.2CO.sub.2.sup.-,
CH.sub.2CH.sub.2CONH.sub.2 or CH.sub.2CH.sub.2CN, [0022] R.sub.2
and R.sub.2' may be the same or different, and each is methyl,
ethyl, propyl, .alpha.-methylpropyl, .beta.-methylpropyl,
.beta.-hydroxyethyl, .beta.-hydroxypropyl, CH.sub.2CO.sub.2.sup.-,
CH(CO.sub.2.sup.-)CH.sub.2CO.sub.2.sup.- or
CH.sub.2CH.sub.2SO.sub.3.sup.- and [0023] p is 1 or 2.
[0024] Especially preferred compounds of formula (I) are those in
which
the anionic charge on the brightener is balanced by a cationic
charge composed of one or more identical or different cations
selected from the group consisting of Na.sup.+, K.sup.+,
triethanolammonium, N-hydroxyethyl-N,N-dimethylammonium,
N-hydroxyethyl-N,N-diethylammonium or mixtures of said compounds,
[0025] R.sub.1 and R.sub.1' may be the same or different, and each
is hydrogen, methyl, ethyl, propyl, .beta.-hydroxyethyl,
.beta.-hydroxypropyl, CH.sub.2CO.sub.2.sup.-,
CH.sub.2CH.sub.2CONH.sub.2 or CH.sub.2CH.sub.2CN, [0026] R.sub.2
and R.sub.2' may be the same or different, and each is ethyl,
propyl, .beta.-hydroxyethyl, .beta.-hydroxypropyl,
CH.sub.2CO.sub.2.sup.-, CH(CO.sub.2.sup.-)CH.sub.2CO.sub.2.sup.- or
CH.sub.2CH.sub.2SO.sub.3.sup.- and [0027] p is 1.
[0028] Compound of formula (I) is used in an amount typically of
from 0.01 to 5% by weight, preferably in the range of from 0.05 to
3% by weight, the % by weight being based on the total weight of
dry white pigment.
[0029] Preferred compounds of formula (II) are those in which
[0030] R.sub.3 signifies H, methyl or ethyl, [0031] R.sub.4
signifies paramethoxyphenyl, methyl or ethyl, [0032] M signifies a
cation selected from the group consisting of hydrogen, an alkali
metal cation, alkaline earth metal, ammonium which is mono-, di-,
tri- or tetrasubstituted by a C.sub.1-C.sub.4 linear or branched
hydroxyalkyl radical, ammonium which is, di-, tri- or
tetrasubstituted by a mixture of C.sub.1-C.sub.4 linear or branched
alkylradical and linear or branched hydroxyalkyl radical or
mixtures of said compounds.
[0033] More preferred compounds of formula (II) are those in which
[0034] R.sub.3 signifies methyl or ethyl, [0035] R.sub.4 signifies
methyl or ethyl, [0036] M signifies a cation selected from the
group consisting of Li.sup.+, Na.sup.+, K.sup.+, 1/2 Ca.sup.2+, 1/2
Mg.sup.2+, ammonium which is mono-, di-, tri- or tetrasubstituted
by a C.sub.1-C.sub.4 linear or branched hydroxyalkyl radical,
ammonium which is, di-, tri- or tetrasubstituted by a mixture of
C.sub.1-C.sub.4 linear or branched alkylradical and linear or
branched hydroxyalkyl radical or mixtures of said compounds.
[0037] Especially preferred compounds of formula (II) are those in
which [0038] R.sub.3 signifies methyl or ethyl, [0039] R.sub.4
signifies methyl or ethyl, [0040] M signifies a cation selected
from the group consisting of Na.sup.+, K.sup.+, triethanolammonium,
N-hydroxyethyl-N,N-dimethylammonium,
N-hydroxyethyl-N,N-diethylammonium or mixtures of said
compounds.
[0041] Compound of formula (II) is used in an amount typically of
from 0.00001 to 0.05% by weight, preferably in the range of form
0.00005 to 0.02% by weight, the % by weight being based on the
total weight of dry white pigment.
[0042] Although it is possible to produce coating compositions that
are free from white pigments, the best white substrates for
printing are made using opaque coating compositions comprise from
10 to 70% by weight of white pigments, preferably of from 40 to 60%
by weight of white pigments, the % by weight being based on the
total weight of the coating composition. Such white pigments are
generally inorganic pigments, e.g., aluminium silicates (kaolin,
otherwise known as china clay), calcium carbonate (chalk), titanium
dioxide, aluminium hydroxide, barium carbonate, barium sulphate, or
calcium sulphate (gypsum). Preferably a mixture of from 10 to 20%
by weight of clay and of from 30 to 40% by weight of chalk is used
as white pigments, the % by weight being based on the total weight
of the coating composition.
[0043] The binders may be any of those commonly used in the paper
industry for the production of coating compositions and may consist
of a single binder or of a mixture of primary and secondary
binders.
[0044] The sole or primary binder is preferably a synthetic latex,
typically a styrene-butadiene, vinyl acetate, styrene acrylic,
vinyl acrylic or ethylene vinyl acetate polymer. The preferred
primary binder is a latex binder.
[0045] The sole or primary binder is used in an amount typically in
the range of form 2 to 25% by weight, preferably of from 4 to 20%
by weight, the % by weight being based on the total weight of white
pigment.
[0046] The secondary binder which may be optionally used may be,
e.g., starch, carboxymethylcellulose, casein, soy polymers,
polyvinyl alcohol or a mixture of any of the above. The preferred
secondary binder which may be optionally used is a polyvinyl
alcohol binder.
[0047] The polyvinyl alcohol which may be optionally used in the
coating composition as secondary binder has preferably a degree of
hydrolysis greater than or equal to 60% and a Brookfield viscosity
of from 2 to 80 mPas (4% aqueous solution at 20.degree. C.). More
preferably, the polyvinyl alcohol has a degree of hydrolysis
greater than or equal to 80% and a Brookfield viscosity of from 2
to 40 mPas (4% aqueous solution at 20.degree. C.).
[0048] When optionally used, the secondary binder is used in an
amount typically in the range of form 0.1 to 20% by weight,
preferably of from 0.2 to 8% by weight, more preferably of from 0.3
to 6% by weight, the % by weight being based on the total weight of
white pigment.
[0049] The pH value of the coating composition is typically in the
range of from 5 to 13, preferably of from 6 to 11, more preferably
of from 7 to 10. Where it is necessary to adjust the pH of the
coating composition, acids or bases may be employed. Examples of
acids which may be employed include but are not restricted to
hydrochloric acid, sulphuric acid, formic acid and acetic acid.
Examples of bases which may be employed include but are not
restricted to alkali metal and alkaline earth metal hydroxide or
carbonates, ammonia or amines.
[0050] In addition to one or more compounds of formula (I), one or
more compounds of formula (II), one or more white pigments, one or
more binders, optionally one or more secondary binders and water,
the coating composition may contain by-products formed during the
preparation of compounds of formula (I) and compounds of formula
(II) as well as other conventional paper additives. Examples of
such additives are for example antifreezers, dispersing agents,
synthetic or natural thickeners, carriers (e.g. polyethylene
glycols), defoamers, wax emulsions, dyes, inorganic salts,
solubilizing aids, preservatives, complexing agents, biocides,
cross-linkers, pigments, special resins etc.
[0051] The coating composition may be prepared by adding one or
more compounds of formula (I) and one or more compounds of formula
(II), to a preformed aqueous dispersion of one or more binders,
optionally one or more secondary binders and one or more white
pigments.
[0052] One or more compounds of formula (I) and one or more
compounds of formula (II) can be added in any order or at the same
time to the preformed aqueous dispersion of one or more binders,
optionally one or more secondary binders and one or more white
pigments.
[0053] One or more compounds of formula (I), one or more compounds
of formula (II) and optionally one or more secondary binders can be
added as solids or as preformed aqueous solutions to the preformed
aqueous dispersion of one or more white pigments.
[0054] The present invention further provides a process for the
optical brightening and tinting of paper substrates characterized
in that an aqueous coating composition containing at least one
optical brightener, at least one certain shading dye, at least one
white pigment, at least one binder and optionally at least one
secondary binder is used.
[0055] When used as a preformed aqueous solution, the concentration
of compound of formula (I) in water is preferably of from 1 to 80%
by weight, more preferably of from 2 to 50% by weight, even more
preferably from 10 to 30% by weight, the % by weight being based on
the total weight of the preformed aqueous solution containing the
compound of formula (I).
[0056] When used as a preformed aqueous solution, the concentration
of compound of formula (II) in water is preferably of from 0.001 to
30% by weight, more preferably of from 0.01 to 25% by weight, even
more preferably from 0.02 to 20% by weight, the % by weight being
based on the total weight of the preformed aqueous solution
containing the compound of formula (II).
[0057] When used as a preformed aqueous solution, the concentration
of secondary binders in water is preferably of from 1 to 50% by
weight, more preferably of from 2 to 40% by weight, even more
preferably from 5 to 30% by weight, the % by weight being based on
the total weight of the preformed aqueous solution containing the
secondary binders.
[0058] The following examples shall demonstrate the instant
invention in more details. In the present application, if not
indicated otherwise, "parts" means "parts by weight" and "%" means
"% by weight".
EXAMPLES
Preparative Example 1
[0059] An aqueous solution (S1) is prepared by slowly adding 157
parts of water to 843 parts of a preformed aqueous mixture
containing 0.210 mol per kg of compound of formula (1) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
difference that the final solution was ultra-filtered to remove
salts and concentrated to 0.210 mol per kg of compound of formula
(1)) at room temperature with efficient stirring. The obtained
mixture is stirred for 1 hour at room temperature to afford 1000
parts of an aqueous solution (S1) containing 0.177 mol per kg of
compound of formula (1). The resulting aqueous solution (S1) has a
pH in the range of from 8.0 to 9.0.
##STR00003##
Preparative Example 1a
[0060] An aqueous solution (S1a) is prepared by slowly adding 2
parts of compound of formula (a) and 155 parts of water to 843
parts of a preformed aqueous mixture containing 0.210 mol per kg of
compound of formula (1) (synthesized according to example 1 in WO
2011/033064-A2 with the sole difference that the final solution was
ultra-filtered to remove salts and concentrated to 0.210 mol per kg
of compound of formula (1)) at room temperature with efficient
stirring. The obtained mixture is stirred for 1 hour at room
temperature to afford 1000 parts of an aqueous formulation (S1a)
containing compound of formula (a) at a concentration of 0.2 weight
%, the weight % being based on the total weight of the final
aqueous formulation (S1a) and 0.177 mol per kg of compound of
formula (1). The resulting aqueous formulation (S1a) has a pH in
the range of from 8.0 to 9.0.
##STR00004##
Preparative Example 1b
[0061] An aqueous solution (S1 b) is prepared by slowly adding 2
parts of compound of formula (b) and 155 parts of water to 843
parts of a preformed aqueous mixture containing 0.210 mol per kg of
compound of formula (1) (synthesized according to example 1 in WO
2011/033064-A2 with the sole difference that the final solution was
ultra-filtered to remove salts and concentrated to 0.210 mol per kg
of compound of formula (1)) at room temperature with efficient
stirring. The obtained mixture is stirred for 1 hour at room
temperature to afford 1000 parts of an aqueous solution (S1b)
containing compound of formula (b) at a concentration of 0.2 weight
%, the weight % being based on the total weight of the final
aqueous solution (S1b) and 0.177 mol per kg of compound of formula
(1). The resulting aqueous solution (S1b) has a pH in the range of
from 8.0 to 9.0.
##STR00005##
Comparative Example 1c
[0062] An aqueous solution (S1c) is prepared by slowly adding 18.2
parts of a preformed aqueous solution containing 11 weight % of
C.I. Direct Violet 35, the weight being based on the total weight
of the aqueous C.I. Direct Violet 35 preformed solution and 138.8
parts of water to 843 parts of a preformed aqueous mixture
containing 0.210 mol per kg of compound of formula (1) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
difference that the final solution was ultra-filtered to remove
salts and concentrated to 0.210 mol per kg of compound of formula
(1)) at room temperature with efficient stirring. The obtained
mixture is stirred for 1 hour at room temperature to afford 1000
parts of an aqueous solution (S1c) containing C.I. Direct Violet 35
at a concentration of 0.2 weight %, the weight % being based on the
total weight of the final aqueous solution (S1c) and 0.177 mol per
kg of compound of formula (1). The resulting aqueous solution (S1c)
has a pH in the range of from 8.0 to 9.0.
Application Example 1
[0063] A coating composition is prepared containing 70 parts chalk
(commercially available under the trade name Hydrocarb 90 from
OMYA), 30 parts clay (commercially available under the trade name
Kaolin SPS from IMERYS), 42.8 parts water, 0.6 parts dispersing
agent (a sodium salt of a polyacrylic acid commercially available
under the trade name Polysalz S from BASF), 20 parts of 50% latex
(a styrene butadiene copolymer commercially available under the
trade name DL 921 from Dow) and 0.8 parts of a polyvinyl alcohol
having a degree of hydrolysis of 98-99% and Brookfield viscosity of
4.0-5.0 mPas (4% aqueous solution at 20.degree. C.). The solids
content of the coating composition is adjusted to approx. 65% by
the addition of water, and the pH is adjusted to 8-9 with sodium
hydroxide.
[0064] Aqueous solutions (S1), (S1a), (S1b) and (S1c) prepared
according to preparative example 1, 1a and 1b and comparative
example 1c respectively are added to the stirred coating
composition at a range of concentrations of from 0 to 2 weight %
(from 0 to 0.4% by weight of compound of formula (1) based on dry
solid), the % by weight being based on the total weight of the dry
pigment.
[0065] The coating composition is then applied to a commercial 75
gsm neutral-sized white paper base sheet using an automatic
wire-wound bar applicator with a standard speed setting and a
standard load on the bar. The coated paper is then dried for 5
minutes in a hot air flow. Afterwards the paper is allowed to
condition and measured then for CIE Whiteness and brightness on a
calibrated Elrepho spectrophotometer. Results are depicted in table
1a and 1b respectively and clearly shows the significant
improvement in whiteness while avoiding the disadvantages
characterized by the use of shading dyes (loss of brightness).
TABLE-US-00001 TABLE 1a CIE Whiteness Solution (S1) from Solution
(S1a) from Solution (S1b) from Conc. preparative preparative
preparative % example 1 example 1a example 1b 0.0 84.2 84.2 84.2
0.3 98.8 100.6 100.6 0.6 106.4 108.9 108.8 0.9 108.9 112.5 111.6
1.2 109.1 114.0 114.0 1.5 109.4 115.7 115.6
TABLE-US-00002 TABLE 1b Brightness Solution (S1) Solution (S1a)
Solution (S1b) Solution (S1c) from from from from Conc. preparative
preparative preparative comparative % example 1 example 1a example
1b example 1c 0.0 88.8 88.8 88.8 88.8 0.3 93.6 93.4 93.6 92.7 0.6
96.3 96.0 95.9 94.0 0.9 98.0 97.1 97.0 93.2 1.2 97.8 96.9 97.0 92.5
1.5 98.2 97.1 97.1 92.1
Preparative Example 2
[0066] An aqueous solution (S2) is prepared by slowly adding 157
parts of water to 843 parts of a preformed aqueous mixture
containing 0.210 mol per kg of compound of formula (2) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that iminodiacetic acid is used instead of
diethanolamine and the final solution is concentrated to 0.210 mol
per kg of compound of formula (2)) at room temperature with
efficient stirring. The obtained mixture is stirred for 1 hour at
room temperature to afford 1000 parts of an aqueous solution (S2)
containing 0.177 mol per kg of compound of formula (2). The
resulting aqueous solution (S2) has a pH in the range of from 8.0
to 9.0.
##STR00006##
Preparative Example 2a
[0067] An aqueous solution (S2a) is prepared by slowly adding 2
parts of compound of formula (a) and 155 parts of water to 843
parts of a preformed aqueous mixture containing 0.210 mol per kg of
compound of formula (2) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that iminodiacetic acid is
used instead of diethanolamine and the final solution is
concentrated to 0.210 mol per kg of compound of formula (2)) at
room temperature with efficient stirring. The obtained mixture is
stirred for 1 hour at room temperature to afford 1000 parts of an
aqueous solution (S2a) containing compound of formula (a) at a
concentration of 0.2 weight %, the weight % being based on the
total weight of the final aqueous solution (S2a) and 0.177 mol per
kg of compound of formula (2). The resulting aqueous solution (S2a)
has a pH in the range of from 8.0 to 9.0.
Preparative Example 2b
[0068] An aqueous solution (S2b) is prepared by slowly adding 2
parts of compound of formula (b) and 155 parts of water to 843
parts of a preformed aqueous mixture containing 0.210 mol per kg of
compound of formula (2) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that iminodiacetic acid is
used instead of diethanolamine and the final solution is
concentrated to 0.210 mol per kg of compound of formula (2)) at
room temperature with efficient stirring. The obtained mixture is
stirred for 1 hour at room temperature to afford 1000 parts of an
aqueous solution (S2b) containing compound of formula (b) at a
concentration of 0.2 weight %, the weight % being based on the
total weight of the final aqueous solution (S2b) and 0.177 mol per
kg of compound of formula (2). The resulting aqueous solution (S2b)
has a pH in the range of from 8.0 to 9.0.
Comparative Example 2c
[0069] An aqueous solution (S2c) is prepared by slowly adding 18.2
parts of a preformed aqueous solution containing 11 weight % of
C.I. Direct Violet 35, the weight % being based on the total weight
of the aqueous C.I. Direct Violet 35 preformed solution and 138.8
parts of water to 843 parts of a preformed aqueous mixture
containing 0.210 mol per kg of compound of formula (2) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that iminodiacetic acid is used instead of
diethanolamine and the final solution is concentrated to 0.210 mol
per kg of compound of formula (2)) at room temperature with
efficient stirring. The obtained mixture is stirred for 1 hour at
room temperature to afford 1000 parts of an aqueous solution (S2c)
containing C.I. Direct Violet 35 at a concentration of 0.2 weight
%, the weight % being based on the total weight of the final
aqueous solution (S2c) and 0.177 mol per kg of compound of formula
(2). The resulting aqueous solution (S2c) has a pH in the range of
from 8.0 to 9.0.
Application Example 2
[0070] A coating composition is prepared containing 70 parts chalk
(commercially available under the trade name Hydrocarb 90 from
OMYA), 30 parts clay (commercially available under the trade name
Kaolin SPS from IMERYS), 42.8 parts water, 0.6 parts dispersing
agent (a sodium salt of a polyacrylic acid commercially available
under the trade name Polysalz S from BASF), 20 parts of 50% latex
(a styrene butadiene copolymer commercially available under the
trade name DL 921 from Dow) and 0.8 parts of a polyvinyl alcohol
having a degree of hydrolysis of 98-99% and Brookfield viscosity of
4.0-5.0 mPas (4% aqueous solution at 20.degree. C.). The solids
content of the coating composition is adjusted to approx. 65% by
the addition of water, and the pH is adjusted to 8-9 with sodium
hydroxide.
[0071] Aqueous solutions (S2), (S2a), (S2b) and (S2c) prepared
according to preparative example 2, 2a and 2b and comparative
example 2c respectively are added to the stirred coating
composition at a range of concentrations of from 0 to 2 weight %
(from 0 to 0.4% by weight of compound of formula (2) based on dry
solid), the % by weight being based on the total weight of the dry
pigment.
[0072] The coating composition is then applied to a commercial 75
gsm neutral-sized white paper base sheet using an automatic
wire-wound bar applicator with a standard speed setting and a
standard load on the bar. The coated paper is then dried for 5
minutes in a hot air flow. Afterwards the paper is allowed to
condition and measured then for CIE Whiteness and brightness on a
calibrated Elrepho spectrophotometer. Results are depicted in table
2a and 2b respectively and clearly shows the significant
improvement in whiteness while avoiding the disadvantages
characterized by the use of shading dyes (loss of brightness).
TABLE-US-00003 TABLE 2a CIE Whiteness Solution (S2) from Solution
(S2a) from Solution (S2b) from Conc. preparative preparative
preparative % example 2 example 2a example 2b 0.0 84.2 84.2 84.2
0.3 99.5 100.6 100.8 0.6 106.4 110.2 109.3 0.9 110.5 114.3 114.4
1.2 111.0 116.4 116.3 1.5 111.1 117.6 117.8
TABLE-US-00004 TABLE 2b Brightness Solution (S2) Solution (S2a)
Solution (S2b) Solution (S2c) from from from from Conc. preparative
preparative preparative comparative % example 2 example 2a example
2b example 2c 0.0 88.8 88.8 88.8 88.8 0.3 93.9 93.6 93.7 93.0 0.6
96.5 96.4 96.2 94.6 0.9 98.1 97.6 97.6 95.4 1.2 98.7 98.0 97.9 95.0
1.5 98.9 97.6 97.5 94.6
Preparative Example 3
[0073] An aqueous solution (S3) is prepared by slowly adding 222.2
parts of water to 777.8 parts of a preformed aqueous mixture
containing 0.157 mol per kg of compound of formula (3) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that aspartic acid is used instead of diethanolamine
and the final solution is concentrated to 0.157 mol per kg of
compound of formula (3)) at room temperature with efficient
stirring. The obtained mixture is stirred for 1 hour at room
temperature to afford 1000 parts of an aqueous solution (S3)
containing 0.122 mol per kg of compound of formula (3). The
resulting aqueous solution (S3) has a pH in the range of from 8.0
to 9.0.
##STR00007##
Preparative Example 3a
[0074] An aqueous solution (S3a) is prepared by slowly adding 2
parts of compound of formula (a) and 220.2 parts of water to 777.8
parts of a preformed aqueous mixture containing 0.157 mol per kg of
compound of formula (3) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that aspartic acid is used
instead of diethanolamine and the final solution is concentrated to
0.157 mol per kg of compound of formula (3)) at room temperature
with efficient stirring. The obtained mixture is stirred for 1 hour
at room temperature to afford 1000 parts of an aqueous solution
(S3a) containing compound of formula (a) at a concentration of 0.2
weight %, the weight % being based on the total weight of the final
aqueous solution (S3a) and 0.122 mol per kg of compound of formula
(3). The resulting aqueous solution (S3a) has a pH in the range of
from 8.0 to 9.0.
Preparative Example 3b
[0075] An aqueous solution (S3b) is prepared by slowly adding 2
parts of compound of formula (b) and 220.2 parts of water to 777.8
parts of a preformed aqueous mixture containing 0.157 mol per kg of
compound of formula (3) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that aspartic acid is used
instead of diethanolamine and the final solution is concentrated to
0.157 mol per kg of compound of formula (3)) at room temperature
with efficient stirring. The obtained mixture is stirred for 1 hour
at room temperature to afford 1000 parts of an aqueous solution
(S3b) containing compound of formula (b) at a concentration of 0.2
weight %, the weight % being based on the total weight of the final
aqueous solution (S3b) and 0.122 mol per kg of compound of formula
(3). The resulting aqueous solution (S3b) has a pH in the range of
from 8.0 to 9.0.
Comparative Example 3c
[0076] An aqueous solution (S3c) is prepared by slowly adding 18.2
parts of a preformed aqueous solution containing 11 weight % of
C.I. Direct Violet 35, the weight % being based on the total weight
of the aqueous C.I. Direct Violet 35 preformed solution and 204.0
parts of water to 777.8 parts of a preformed aqueous mixture
containing 0.157 mol per kg of compound of formula (3) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that aspartic acid is used instead of diethanolamine
and the final solution is concentrated to 0.157 mol per kg of
compound of formula (3)) at room temperature with efficient
stirring. The obtained mixture is stirred for 1 hour at room
temperature to afford 1000 parts of an aqueous solution (S3c)
containing C.I. Direct Violet 35 at a concentration of 0.2 weight
%, the weight % being based on the total weight of the final
aqueous solution (S3c) and 0.122 mol per kg of compound of formula
(3). The resulting aqueous solution (S3c) has a pH in the range of
from 8.0 to 9.0.
Application Example 3
[0077] A coating composition is prepared containing 70 parts chalk
(commercially available under the trade name Hydrocarb 90 from
OMYA), 30 parts clay (commercially available under the trade name
Kaolin SPS from IMERYS), 42.8 parts water, 0.6 parts dispersing
agent (a sodium salt of a polyacrylic acid commercially available
under the trade name Polysalz S from BASF), 20 parts of 50% latex
(a styrene butadiene copolymer commercially available under the
trade name DL 921 from Dow) and 0.8 parts of a polyvinyl alcohol
having a degree of hydrolysis of 98-99% and Brookfield viscosity of
4.0-5.0 mPas (4% aqueous solution at 20.degree. C.). The solids
content of the coating composition is adjusted to approx. 65% by
the addition of water, and the pH is adjusted to 8-9 with sodium
hydroxide.
[0078] Aqueous solutions (S3), (S3a), (S3b) and (S3c) prepared
according to preparative example 3, 3a and 3b and comparative
example 3c respectively are added to the stirred coating
composition at a range of concentrations of from 0 to 2 weight %
(from 0 to 0.4% by weight of compound of formula (3) based on dry
solid), the % by weight being based on the total weight of the dry
pigment.
[0079] The coating composition is then applied to a commercial 75
gsm neutral-sized white paper base sheet using an automatic
wire-wound bar applicator with a standard speed setting and a
standard load on the bar. The coated paper is then dried for 5
minutes in a hot air flow. Afterwards the paper is allowed to
condition and measured then for CIE Whiteness and brightness on a
calibrated Elrepho spectrophotometer. Results are depicted in table
3a and 3b respectively and clearly shows the significant
improvement in whiteness while avoiding the disadvantages
characterized by the use of shading dyes (loss of brightness).
TABLE-US-00005 TABLE 3a CIE Whiteness Solution (S3) from Solution
(S3a) from Solution (S3b) from Conc. preparative preparative
preparative % example 3 example 3a example 3b 0.0 84.3 84.3 84.3
0.3 95.9 96.4 96.9 0.6 102.3 103.4 105.3 0.9 106.5 107.8 110.2 1.2
109.5 111.4 114.7 1.5 110.7 113.1 117.4
TABLE-US-00006 TABLE 3b Brightness Solution (S3) Solution (S3a)
Solution (S3b) Solution (S3c) from from from from Conc. preparative
preparative preparative comparative % example 3 example 3a example
3b example 3c 0.0 89.2 89.2 89.2 89.2 0.3 92.8 92.5 92.5 92.1 0.6
95.0 94.6 94.7 93.7 0.9 96.5 95.9 96.1 94.2 1.2 97.7 96.8 96.9 94.3
1.5 98.3 97.2 97.4 94.5
Preparative Example 4
[0080] An aqueous solution (S4) is prepared by slowly adding 222.2
parts of water to 777.8 parts of a preformed aqueous mixture
containing 0.157 mol per kg of compound of formula (4) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that diisopropanolamine is used instead of
diethanolamine and the final solution is concentrated to 0.157 mol
per kg of compound of formula (4)) at room temperature with
efficient stirring. The obtained mixture is stirred for 1 hour at
room temperature to afford 1000 parts of an aqueous solution (S4)
containing 0.122 mol per kg of compound of formula (4). The
resulting aqueous solution (S4) has a pH in the range of from 8.0
to 9.0.
##STR00008##
Preparative Example 4a
[0081] An aqueous solution (S4a) is prepared by slowly adding 2
parts of compound of formula (a) and 220.2 parts of water to 777.8
parts of a preformed aqueous mixture containing 0.157 mol per kg of
compound of formula (4) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that diisopropanolamine is
used instead of diethanolamine and the final solution is
concentrated to 0.157 mol per kg of compound of formula (4)) at
room temperature with efficient stirring. The obtained mixture is
stirred for 1 hour at room temperature to afford 1000 parts of an
aqueous solution (S4a) containing compound of formula (a) at a
concentration of 0.2 weight %, the weight % being based on the
total weight of the final aqueous solution (S4a) and 0.122 mol per
kg of compound of formula (4). The resulting aqueous solution (S4a)
has a pH in the range of from 8.0 to 9.0.
Preparative Example 4b
[0082] An aqueous solution (S4b) is prepared by slowly adding 2
parts of compound of formula (b) and 220.2 parts of water to 777.8
parts of a preformed aqueous mixture containing 0.157 mol per kg of
compound of formula (4) (synthesized according to example 1 in WO
2011/033064-A2 with the sole differences that diisopropanolamine is
used instead of diethanolamine and the final solution is
concentrated to 0.157 mol per kg of compound of formula (4)) at
room temperature with efficient stirring. The obtained mixture is
stirred for 1 hour at room temperature to afford 1000 parts of an
aqueous solution (S4b) containing compound of formula (b) at a
concentration of 0.2 weight %, the weight % being based on the
total weight of the final aqueous solution (S4b) and 0.122 mol per
kg of compound of formula (4). The resulting aqueous solution (S4b)
has a pH in the range of from 8.0 to 9.0.
Comparative Example 4c
[0083] An aqueous solution (S4c) is prepared by slowly adding 18.2
parts of a preformed aqueous solution containing 11 weight % of
C.I. Direct Violet 35, the weight % being based on the total weight
of the aqueous C.I. Direct Violet 35 preformed solution and 204.0
parts of water to 777.8 parts of a preformed aqueous mixture
containing 0.157 mol per kg of compound of formula (4) (synthesized
according to example 1 in WO 2011/033064-A2 with the sole
differences that diisopropanolamine is used instead of
diethanolamine and the final solution is concentrated to 0.157 mol
per kg of compound of formula (4)) at room temperature with
efficient stirring. The obtained mixture is stirred for 1 hour at
room temperature to afford 1000 parts of an aqueous solution (S4c)
containing C.I. Direct Violet 35 at a concentration of 0.2 weight
%, the weight % being based on the total weight of the final
aqueous solution (S4c) and 0.122 mol per kg of compound of formula
(4). The resulting aqueous solution (S4c) has a pH in the range of
from 8.0 to 9.0.
Application Example 4
[0084] A coating composition is prepared containing 70 parts chalk
(commercially available under the trade name Hydrocarb 90 from
OMYA), 30 parts clay (commercially available under the trade name
Kaolin SPS from IMERYS), 42.8 parts water, 0.6 parts dispersing
agent (a sodium salt of a polyacrylic acid commercially available
under the trade name Polysalz S from BASF), 20 parts of 50% latex
(a styrene butadiene copolymer commercially available under the
trade name DL 921 from Dow) and 0.8 parts of a polyvinyl alcohol
having a degree of hydrolysis of 98-99% and Brookfield viscosity of
4.0-5.0 mPas (4% aqueous solution at 20.degree. C.). The solids
content of the coating composition is adjusted to approx. 65% by
the addition of water, and the pH is adjusted to 8-9 with sodium
hydroxide.
[0085] Aqueous solutions (S4), (S4a), (S4b) and (S4c) prepared
according to preparative example 4, 4a and 4b and comparative
example 4c respectively are added to the stirred coating
composition at a range of concentrations of from 0 to 2 weight %
(from 0 to 0.4% by weight of compound of formula (4) based on dry
solid), the % by weight being based on the total weight of the dry
pigment.
[0086] The coating composition is then applied to a commercial 75
gsm neutral-sized white paper base sheet using an automatic
wire-wound bar applicator with a standard speed setting and a
standard load on the bar. The coated paper is then dried for 5
minutes in a hot air flow. Afterwards the paper is allowed to
condition and measured then for CIE Whiteness and brightness on a
calibrated Elrepho spectrophotometer. Results are depicted in table
4a and 4b respectively and clearly shows the significant
improvement in whiteness while avoiding the disadvantages
characterized by the use of shading dyes (loss of brightness).
TABLE-US-00007 TABLE 4a CIE Whiteness Solution (S4) from Solution
(S4a) from Solution (S4b) from Conc. preparative preparative
preparative % example 4 example 4a example 4b 0.0 84.3 84.3 84.3
0.3 96.7 98.2 98.0 0.6 103.1 105.5 105.9 0.9 107.6 110.5 110.2 1.2
110.0 115.1 115.1 1.5 111.1 118.6 117.1
TABLE-US-00008 TABLE 4b Brightness Solution (S4) Solution (S4a)
Solution (S4b) Solution (S4c) from from from from Conc. preparative
preparative preparative comparative % example 4 example 4a example
4b example 4c 0.0 89.2 89.2 89.2 89.2 0.3 93.0 92.9 92.8 92.2 0.6
95.2 94.9 94.9 93.3 0.9 96.8 96.0 96.0 93.1 1.2 97.7 97.0 97.1 93.1
1.5 98.3 97.3 97.3 92.5
* * * * *