OPTICAL BRIGHTENER AND METHOD OF PREPARING IT

AZUREUR OPTIQUE ET PROCEDE DE PREPARATION ASSOCIE

English Abstract

The present invention relates generally to an improved method of preparing
aqueous coating compositions including an optical brightener and a polyvinyl
alcohol resin, the improvement being directed to cooking a slurry to dissolve
the polyvinyl alcohol resin subsequent to the addition of optical brightener
and polyvinyl alcohol resin to the slurry at a temperature above about 160~F
for at least about 5 minutes. The invention enables preparation with lower
water content without compromising brightness and color. Particularly
preferred is the addition of dry resin and/or dry brightener to provide high
solids mixtures. Another aspect of the invention is a dry, particulate blend
of brightener and PVOH resin. Disclosed is a method of preparing an optical
brightener/PVOH aqueous concentrate comprising the sequential steps of: (a)
providing an aqueous brightener composition including water and optical
brightener active ingredient, wherein the optical brightener active ingredient
is typically present in the aqueous brightener composition in an amount of
from about 10% to about 25%; (b) admixing a polyvinyl alcohol resin with said
aqueous optical brightener composition in an amount of about 1 part of dry
polyvinyl alcohol resin per 0.5 to 10 wet parts of aqueous brightener
composition to provide a nascent aqueous concentrate of polyvinyl alcohol
resin and optical brightener; and (c) cooking the aqueous concentrate to
dissolve the solids typically at a temperature of from about 175~F to about
210~F for a time of from about 10 minutes to about 120 minutes to provide a
conked brightener/polyvinyl alcohol concentrate.

French Abstract

L'invention concerne un procédé amélioré de préparation de compositions de revêtement aqueuses contenant un azureur optique une résine d'alcool polyvinylique, cette amélioration consistant à cuire une boue afin de dissoudre la résine d'alcool polyvinylique après avoir ajouté l'azureur optique et la résine d'alcool polyvinylique dans la boue à une température supérieure à 160 ·F environ pendant près de 5 minutes. Cette invention permet une préparation avec une teneur en eau inférieure sans compromettre la brillance et la couleur. Une préférence particulière est donnée à l'ajout de résine sèche et/ou d'azureur sec afin d'obtenir des mélanges à teneur élevée en solides. L'invention porte aussi sur une mélange particulaire sec d'azureur et de résine PVOH. L'invention se rapporte aussi à un procédé de préparation d'un azureur optique/d'une concentration aqueuse PVOH comprenant plusieurs étapes consistant : (a) à fournir une composition d'azureur aqueuse contenant de l'eau et un ingrédient actif azureur optique, l'ingrédient actif d'azureur optique étant généralement présent dans la composition d'azureur aqueuse selon une quantité comprise entre 10 et 25 % environ ; (b) à mélanger une résine d'alcool polyvinylique avec la composition d'azureur optique aqueuse selon une quantité de l'ordre d'une portion de résine d'alcool polyvinylique par 0,5 à 10 portions sèches de composition d'azureur aqueuse afin d'obtenir une concentration aqueuse à l'état naissant de résine d'alcool polyvinylique et d'azureur optique ; et (c) à cuire la concentration aqueuse afin de dissoudre les solides généralement à une température comprise entre 175 ·F et 210 ·F environ pendant 10 minutes à 120 minutes environ afin d'obtenir un azureur cuit/une concentration d'alcool polyvinylique.

Claims

30
CLAIMS
What is claimed is:
1. A method of preparing an optical brightener/PVOH aqueous concentrate
comprising the sequential steps of:
a) providing an aqueous brightener composition including water and optical
brightener
active ingredient;
b) admixing a polyvinyl alcohol resin with said aqueous optical brightener
composition in
an amount of about 1 part of dry polyvinyl alcohol resin per 0.25 to 10 wet
parts of aqueous
brightener composition to provide a nascent aqueous concentrate of polyvinyl
alcohol resin and
optical brightener; and
c) cooling the aqueous concentrate to dissolve the solids at an elevated
temperature for a
time sufficient to dissolve substantially all of the polyvinyl alcohol resin
so as to provide a
cooled brightener/polyvinyl alcohol concentrate including water, polyvinyl
alcohol resin,
optical brightener, and optionally minor amounts of auxiliaries.
2. The method according to Claim 1, wherein the optical brightener active
ingredient is present in the aqueous brightener composition in an amount of
from about 10% to
about 25%.
3. The method according to Claim 1, wherein the optical brightener/PVOH
aqueous
concentrate has a solids content of from about 20% to about 75% based on the
water, polyvinyl
alcohol and optical brightener active ingredient content of the concentrate.
4. The method according to Claim 1, wherein said polyvinyl alcohol is admixed
with said aqueous optical brightener composition in an amount of from about
15% to about 55%
PVOH based on the combined weight'of said water, said optical brightener
active ingredient and
said polyvinyl alcohol resin, the concentrate having a solids content of from
about 30 to about
60%.
5. The method according to Claim 1, wherein said aqueous concentrate is cooked
to
dissolve said solids at a temperature of from about 175°F to about
210°F for a time of from
about 10 minutes to about 120 minutes.
6. The method according to Claim 1, wherein the polyvinyl alcohol resin has a
viscosity of from about 2 cps to about 40 cps.
7. The method according to Claim 1, wherein the polyvinyl alcohol resin is
hydrolyzed on a mole percent basis of from about 80 to about 99.5 percent.


31
8. The method according to Claim 1, wherein the polyvinyl alcohol resin is
added to
the aqueous brightener composition in substantially dry form.
9. The method according to Claim 1, further comprising the step of diluting
the
aqueous concentrate.
10. The method according to Claim 1, further comprising the step of adding
polyethylene glycol to said aqueous brightener composition or to said nascent
or cooked
aqueous concentrate.
11. The method according to Claim 10, wherein said polyethylene glycol is
added to
said aqueous brightener composition or to said nascent or cooked aqueous
concentrate in an
amount of from about 0.5 to about 2 parts by weight per dry part of polyvinyl
alcohol resin.
12. The method according to Claim 1, wherein the optical brightener/PVOH
concentrate includes a minor amount of at least one auxiliary selected from
dispersing agents,
productive colloids, solvents for the colloids, antifreeze, sequestering
agents, binder, plasticizer,
filler and water retention aids.
13. The method according to Claim 1, further comprising the step of applying
the
optical brightener/PVOH concentrate directly to a paper substrate.
14. A method of preparing a color coat composition comprising the sequential
steps
of:
(a) providing an aqueous brightener composition including water and optical
brightener
active ingredient;
(b) admixing a polyvinyl alcohol resin with said aqueous optical brightener
composition in
an amount of about 1 part of dry polyvinyl alcohol resin per 0.5 to 10 wet
parts of aqueous
brightener composition to provide a nascent aqueous concentrate of polyvinyl
alcohol resin and
optical brightener;
(c) cooking the aqueous concentrate to dissolve the solids at an elevated
temperature for a
time sufficient to dissolve substantially all of the polyvinyl alcohol resin
so as to provide a
cooked brightener/polyvinyl alcohol concentrate of water, polyvinyl alcohol
resin and optical
brightener, and optionally minor amounts of auxiliaries; and
(d) admixing the cooked concentrate with an aqueous dispersion comprising
color pigment
and a binder resin to produce the color coat composition.
15. The method according to Claim 14, further comprising the step of applying
said
color coat to paper.

32
16. The method according to Claim 14, wherein the polyvinyl alcohol resin is
added
to the optical brightener composition in substantially dry form.
17. An optical brightener aqueous concentrate consisting essentially of water,
an
optical brightener active ingredient and a polyvinyl alcohol resin having a
viscosity of from
about 2 cps to about 4 cps, wherein the aqueous concentrate is from about 20
to about 75%
solids, and wherein the polyvinyl alcohol resin is hydrolyzed from about 80 to
about 90 percent
on a molar basis.
18. The optical brightener concentrate according to Claim 17 wherein the
optical
brightener active ingredient comprises a stilbene compound.
19. The optical brightener concentrate according to Claim 18, wherein the
stilbene
compound is a sulfonated stilbene compound.
20. The optical brightener concentrate according to Claim 19, wherein the
sulfonated
stilbene compound is a tetrasulfonated stilbene compound.
21. The optical brightener concentrate according to Claim 19, wherein the
sulfonated
stilbene compound is a hexasulfonated stilbene compound.
22. The optical brightener concentrate according to Claim 17, wherein the
optical
brightener active ingredient comprises a stilbene compound of the formula:
<IMG>
wherein X and Y are independently selected from the moieties indicated below:


33
<IMG>
23. An optical brightener aqueous concentrate consisting essentially of water,
an
optical brightener active ingredient, polyethylene glycol and polyvinyl
alcohol resin having a
viscosity of from about 3 cps to about 4 cps, wherein the aqueous concentrate
is from about 20
to about 75 % solids, and wherein the polyvinyl alcohol resin is hydrolyzed
from about 80 to
about 90 percent on a molar basis.
24. In a method of preparing an aqueous composition including an optical
brightener
and a polyvinyl alcohol resin, the improvement comprising cooking a slurry to
dissolve
polyvinyl alcohol resin subsequent to the addition of optical brightener and
polyvinyl alcohol
resin to the slurry at a temperature above about 160°F for at least
about 5 minutes.
25. The improvement according to Claim 24, wherein the optical brightener is
added
to the slurry in substantially dry form.
26. The improvement according to Claim 24, wherein the polyvinyl alcohol resin
is
added to an optical brightener solution in substantially dry form in order to
form the slurry.
27. A method of preparing an optical brightener/PVOH aqueous concentrate
comprising the sequential steps of:
a) preparing a PVOH slurry;
b) adding a dry, particulate optical brightener to the PVOH slurry; and
c) cooking the slurry containing PVOH and optical brightener to dissolve the
PVOH
resin for at least 5 minutes at a temperature of above about 160°F.


34
28. A method of preparing an optical brightener/PVOH aqueous concentrate
comprising the sequential steps of:
a) providing a dry powder optical brightener;
b) providing a dry polyvinyl alcohol resin;
c) dry blending said polyvinyl alcohol resin with said optical brightener in
an
amount of about 1 part of dry polyvinyl alcohol resin per 0.05 to 1 dry part
of optical brightener;
d) admixing said dry blend with water to provide a nascent aqueous concentrate
of
polyvinyl alcohol resin and optical brightener; and
e) cooking the aqueous concentrate to dissolve the solids at an elevated
temperature
for a time sufficient to dissolve substantially all of the polyvinyl alcohol
resin and optical
brightener so as to provide a cooked brightener/polyvinyl alcohol concentrate
including water,
polyvinyl alcohol resin, optical brightener, and optionally minor amounts of
auxiliaries.
29. A method of preparing an color coat composition comprising:
a) preparing an aqueous pigment dispersion;
b) preparing a dry blend of polyvinyl alcohol resin and optical brightener,
wherein
the polyvinyl alcohol resin is from about 85 mol% to about 90 mol% hydrolyzed
and has a fine
particle size, such that at least about 99% of the particles pass an 80 mesh
sieve;
c) adding the dry blend of polyvinyl alcohol resin and optical brightener to
the
pigment dispersion; and
d) applying shear to the pigment dispersion containing the polyvinyl alcohol
and
optical brightener so as to mix the dispersion and dissolve both the optical
brightener and
polyvinyl alcohol resin without external heating.
30. The method according to Claim 29, further comprising adding a latex binder
to
the pigment dispersion.
31. The method according to Claim 29, wherein the pigment dispersion contains
a
mineral pigment selected from clay, calcium carbonate, titanium dioxide and
mixtures thereof.
32. A dry, particulate dry blend of a polyvinyl alcohol resin and an optical
brightener.

Description

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
OPTICAL BRIGHTENER AND METHOD OF PREPARING IT
Cross Reference to Related Application
This non-provisional application is a continuation-in-part of United States
Patent
Application Serial No. 10/731,495 entitled "Polyvinyl Alcohol and Optical
Brightener
Concentrate", filed on December 9, 2003, the priority of which is claimed.
Technical Field
The present invention relates to a novel methodology and products for
preparing
mixtures of polyvinyl alcohol (PVOH) and optical brighteners having lugh
solids for easier
drying and faster production rates. The coatings made with the compositions
axe especially
suited for high quality coated papers.
Baclc~round of the Invention
Paper coating compositions, or coating colors, axe used by the paper industry
to impart
the desired moisture resistance, physical properties and appearance to certain
grades of finished
paper. Generally, the coating composition is an aqueous dispersion consisting
mainly of mineral
pigments like clay, calcium carbonate or titanium dioxide, and pigment binders
of natural
protein, staxch or synthetic polymer emulsions. Styrene-butadienes and
polyvinyl acetates are
examples of such synthetic emulsion binders. Coating compositions may also
contain additives,
such as thiclceners, humectants and lubricants.
Coating compositions are usually applied to a continuous web of material by
high speed
coating machines, such as blade coaters, air knife coaters, rod coaters and
roll coaters. It is
advantageous to use faster coaters to increase productivity and to use higher
solids coating
compositions to decrease drying costs and improve binder distribution.
High brightness coated grades of paper typically include optical brighteners
(OBs).
Optical brighteners generally operate by way of absorbing ultra-violet
radiation and then
immediately re-admitting in the visible blue-white range. Examples of optical
brighteners
include UVITEX" and T1NOPAL° from Ciba Specialty Chemicals,
BLANKOPHOR° from
Bayer and HOSTALUX° and LEUCOPHOR° from Clariant. Most OBs have
active ingredients
that belong to the stilbene class of compounds as shown in Structures A, S,
and C:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
2
Sc7~M SO.~M
R~ R~
A
where M can be H, an allcali metal, ammonium or magnesium and R1 represents
hydrogen, C1-
CS allcyl, C1-CS allcoxy or halogen.
Such compounds also include those of Structure B, below:
B
Y
Uuted States Patent No. 5,057,570 to Air Products and Chemicals, October 15,
1991,
describes a process for producing paper coating compositions using partially
hydrolyzed, low
molecular weight polyvinyl alcohol. The advantage of using this polymer is
that no external
heating is required and that it can be added as a dry solid to the aqueous
pigment dispersion.
This can be accomplished under high shear stirring, typically at speeds of
1500 rpm for 5
minutes at room temperature.
United States Patent No. 5,830,241 to Ciba Specialty Chemicals, November 3,
1998,
describes a liquid preparation of a fluorescent whitening agent, low MW
polyethylene glycol,
water and auxiliary compounds. The polyethylene glycol is in liquid form and
functions as the
non-volatile solvent to stabilize liquid preparations of the agent when stored
at elevated
temperatures (50°C). The low MW of the polyethylene glycol has a low
viscosity, which results
in a pumpable solution. A typical structure of the fluorescent whitening agent
is:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
3
C
where M is H, an allcali metal, ammonium or magnesium and polyvinyl alcohol
(PVOH) is a
preferred carrier.
United States Patent No. 6,521,701 to Coatex S.A.S., February 18, 2003,
describes a
stable aqueous liquid polymer composition containing polyvinyl alcohol in
combination with a
homopolymer or copolymer of carboxylic acid in completely acid form. This
combination of
polymers has been fou~.id to optimize the function of water retention, which
activates optical
brighteners, and which controls the viscosity of coating colors. This is all
accomplished without
degrading the water-retention property.
United States Patent No. 6,620,294 to Ciba Specialty Chemicals, September 16,
2003,
describes stable aqueous solutions of fluorescent whitening agents that
contain polyvinyl
alcohol. The solutions can be prepared by mixing a moist press filter calve or
dry powder of a
fluorescent whitening agent with an aqueous solution of a modified or
unmodified polyvinyl
alcohol, with or without optional additives, and heating and mixing tmtil a
homogeneous
distribution is obtained.
While OBs alone worlc well, the inclusion of PVOH boosts their performance. In
some
cases, paper makers use standard PVOH grades purchased in dry form which are
then prepared
for use by cooking in conventional batch vessels. A disadvantage of this
methodology is that the
water used in the PVOH cools dilutes the coating formulation by a significant
amount, which can
negatively impact production rates. In addition, there is a cost to the mill
for cooking PVOH;
and, in many cases, that cost is compounded with problems because of
inadequate equipment or
poorly trained operators. Generally, PVOH is supplied to papermalcers in a
variety of forms: 1)
dry resin that is coolced in water by the customer at 20% to 30% solids, the
advantage being that
less costly grades of PVOH can be used, 'the drawbacks being noted above; 2)
PVOH that has
been pre-cooked acid delivered to the customer at 15% to 25% solids, which is
costly to the
papermalcer as it involves shipping mostly water; and 3) dry, fme particle
size partially
hydrolyzed grades that are added dry to the pigmented formulations. These
latter products are
relatively expensive ground material, but are convenient if coolcing is not an
option. See United

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
4
States Patent No. 5,057,570. See also United States Patent No. 6,620,294 where
there are
described solutions of PVOH and optical brighteners prepared by thoroughly
mixing the moist
press calve or the dry powder of a fluorescent whitening agent with an aqueous
solution of
PVOH and heating.
It has been found in accordance with the present invention that optical
brighteners and
relatively inexpensive grades of PVOH can both be directly incorporated into
water to form a
slurry, followed by cooling the mixture to solubilize the materials, to
produce an aqueous
brightener composition; providing product and manufacturing options not
previously possible.
It is possible to use dry blends of PVOH resin and powdered optical brightener
or to use either
component in dry form.
Summary of the Invention
There is provided in accordance with the present invention a method of
preparing an
optical brightener/PVOH aqueous concentrate by way of the sequential steps o~
(a) providing
an aqueous brightener composition consisting essentially ofmcluding water and
optical
brightener active ingredient, wherein the optical brightener active ingredient
is present in the
aqueous brightener composition typically in an amount of from about,10% to
about 25%; (b)
admixing a polyvinyl alcohol resin with said aqueous optical brightener
composition in an
amount of about 1 part of dry polyvinyl alcohol resin per 0.50.25 to 10 wet
parts of aqueous
brightener composition to provide a nascent aqueous concentrate of polyvinyl
alcohol resin and
optical brightener; and (c) cooling the aqueous concentrate to dissolve the
solidssubstantially all
of the PVOH resin, usually at a temperature of from about 175°F to
about 210°F generally for a
time of from about 10 minutes to about 120 minutes to provide a cool{ed
brightener/polyvinyl
alcohol concentrate consisting essentially of water, polyvinyl alcohol resin
and optical
brightener active ingredient. Typically, the polyvinyl alcohol resin is
admixed in an amount of
about 1 part of dry polyvinyl alcohol resin per 0.5 to 10 wet parts of aqueous
brightener
composition.
The optical brightener active ingredient is generally usually present in the
aqueous
brightener composition in an amount of from about 12% to about 20% and the
optical
brightener/PVOH aqueous concentrate typically has a solids content of from
about 20% to about
75% based on the water, polyvinyl alcohol and optical brightener
active.ingredient content of the
concentrate. More typically, the polyvinyl alcohol is admixed with the aqueous
optical
brightener composition in an amount of from about 15% to about 55% PVOH based
on the

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
combined weight of the water, the optical brightenex active ingredient and
polyvinyl alcohol
resin, the concentrate having a solids content of from about 30 to about 60%.
Likewise, the
aqueous concentrate is usually coolced to dissolve the solids at a temperature
of from about
185°F to about 205°F for a time of from about 20 minutes to
about 60 minutes. Suitable
polyvinyl alcohol resins have viscosities of from about 2 or 3 cps to about 30
or 40 cps; most
preferably in some cases the polyvinyl alcohol resin has a viscosity of from
about 2 or 3 cps to
about 5 7 or 8 cps or from about 3 cps to about 4 cps.
The polyvinyl alcohol resin is generally hydrolyzed on a mole percent basis of
from
about 85 80 to about 99.5 percent; typically, the polyvinyl alcohol resin is
hydrolyzed on a mole
percent basis of from about 85 percent to about 90 percent and has a degree of
polymerization of
from about 50 to about 25002000. A degree of polymerization of from about 50
to about 1700
is more preferred as is a degree of polymerization of from about 50 to about
300
Most preferably, the polyvinyl alcohol resin is added to the aqueous polyvinyl
alcoholbrightener composition in substantially dry form; and sometimes the
step of diluting the
aqueous concentrate is expedient, depending on processing characteristics
sought. So also, the
concentrate cam be directly applied to a paper substrate in a size press, if
so desired.
The method may further include the step of adding polyethylene glycol to the
aqueous
concentrate and wherein the polyethylene glycol is added to the aqueous
brightener composition
or to the nascent or coolced aqueous concentrate in an amount of from about
0.5 to about 2 parts
by weight per dry part of polyvinyl alcohol resin.
A prefeiTed method of preparing a color coat composition includes the
sequential steps
of:
(a) providing am aqueous brightener composition consisting essentially of
water and optical
brightener active ingredient, wherein the optical brightener active ingredient
is present in the
aqueous brightener composition in an amount of from about 10 to about 25%;
(b) admixing a polyvinyl alcohol resin with said aqueous optical brightener
composition in
an amount of about 1 part of dry polyvinyl alcohol resin per 0.25 to 10 wet
parts of aqueous
brightener composition to provide a nascent aqueous concentrate of polyvinyl
alcohol resin and
optical brightener;
(c) cooking the aqueous concentrate to dissolve the solids at a temperature of
from about
175°F to about 210°F for a time of from about 10 minutes to
about 120 minutes to provide a
coolced brightener/polyvinyl alcohol concentrate consisting essentially of
water, polyvinyl
alcohol resin and optical brightener compounds; and

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
6
(d) admixing the cooked concentrate with an aqueous dispersion comprising
color pigment
and a binder resin to produce the color coat composition. Typically, the
polyvinyl alcohol resin
is admixed in an amount of about 1 part of dry polyvinyl alcohol resin per 0.5
to 10 wet parts of
aqueous brightener composition.
The method furthex comprises the step of applying the color coat to paper.
An optical brightener aqueous concentrate consists essentially of water, an
optical
brightener active ingredient and a polyvinyl alcohol resin having a viscosity
of from about 3 2
cps to about 5 4 cps, wherein the aqueous concentrate is from about 20 to
about 75% solids, and
the polyvinyl alcohol resin is hydrolyzed from about 85 80 to about 90 percent
on a molar basis.
The concentrate optionally includes auxiliaries such as dispersing agents,
protective colloids,
solvents for the colloids, and/or antifreezes, sequestering agents and the
like, none of which
change the basic and novel characteristics of the concentrates. When referring
to the optical
brightener/PVOH aqueous concentrate, auxiliaries also include minor amounts of
binder,
plasticizer, filler, water retention aids such as carboxymethyl cellulose and
so forth. Typically,
the polyvinyl alcohol resin has a viscosity of from 3 cps to 4 cps and the
aqueous concentrate is
from about 25 to about 65 percent solids. The optical brightener concentrate
further comprises
polyethylene glycol in some cases and the optical brightener active ingredient
comprises a
stilbene compound. The stilbene compound may be a sulfonated stilbene compound
of the
formula:
wherein X and Y are independently selected from the moieties in the
following table.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
7
Disulfo T_etrasulfo 1 ~ Tetrasulfo 2 Hexasulfo
3
CH2CH20H
-N\ ~CH2CH20H -N CH2CHOH ~CH2CH20H
CH2CH20H -N\ NCH CHOH N\
CH2CH20H 2~ CH2CH20H
CH3
-N N N S03Na
H
-N
Y
~S03Na S03Na Na03S
Thus, the brightener active ingredient may be disulfonated, tetrasulfonated or
hexasulfonated in various embodiments.
In still yet another aspect of the invention, an optical brightener aqueous
concentrate
consists essentially of water, an optical brightener active ingredient,
polyethylene glycol and a
polyvinyl alcohol resin has a viscosity of from about 2 cps to about 4 cps,
wherein the aqueous
concentrate is from about 20 to about 75% solids, and wherein the polyvinyl
alcohol resin is
hydrolyzed from about 80 to about 90 percent on a molar basis.
The present invention further relates generally to improved methods of
preparing
aqueous compositions including an optical brightener and a polyvinyl alcohol
resin, the
improvement being directed to cooking a PVOH containing slurry to dissolve the
polyvinyl
alcohol resin subsequent toAthe addition of optical brightener and polyvinyl
alcohol resin at a
temperature above about 160°F for at least about 5 minutes. The
invention enables preparation
of lower water content formulations without compromising brightness and color.
Particularly
preferred is the addition of dry resin andfor dry brightener to provide high
solids mixtures.
Another aspect of the invention is a method of providing PVOH and optical
brightener to a color
coat composition without external heating. Still another aspect of the
invention is a dry,
particulate blend of brightener and PVOH resin, the details of which are
described hereinafter.
Brief Description of Figures
The invention is illustrated in comiection with the various Figures, wherein:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
8
Figures 1-4 are histograms presenting the Hunter Color data of the coatings of
Examples
11, 12 and Comparative Examples F, G; and
Figures 5-8 are histograms presenting the Hunter Color data of the coatings of
Examples
17, 18 and Comparative Examples H-M.
Detailed Description of the Invention
The present invention is described in detail below with reference to numerous
embodiments for purposes of illustration only. Modifications witlun the spirit
and scope of the
invention, set forth in the appended claims, will be readily apparent to those
of skill in the art.
In some cases, the optical brightener is added to an aqueous composition such
as a PVOH slurry
in substantially dry form; in other embodiments, the polyvinyl alcohol resin
is added to an
aqueous optical brightener solution in substantially dry form; while in still
other embodiments
both the optical brightener and the polyvinyl alcohol resin are added to water
in substantially dry
form, to form a slurry.
In some preferred applications of the inventive process, the slurry is coolced
at a
temperature of at least about 175°F for at least 10 minutes subsequent
to the addition of optical
brightener and polyvinyl alcohol resin. Typically, the slurry is coolced at a
temperature above
about 160°F for at least bout 10 minutes subsequent to the addition of
polyvinyl alcohol resin
and optical brightener and polyvinyl alcohol resin; usually the slurry is
coolced at a temperature
above about 160°F for at least bout 20 minutes subsequent to the
addition of polyvinyl alcohol
resin and optical brightener and polyvinyl alcohol resin. In many cases, the
slurry is cooled at a
temperature of from about 175°F to about 210°F for a time of
from about 10 minutes to about
120 minutes subsequent to the addition of polyvinyl alcohol resin and optical
brightener.
Perhaps most preferably, the aqueous composition is coolced at a temperature
of from about
185°F to about 205°F for a time of from about 20 minutes to
about 60 minutes subsequent to the
addition of polyvinyl alcohol resin and optical brightener.
Suitable polyvinyl alcohol resins have a viscosity of from about 2 cps to
about 40 cps;
typically, the polyvinyl alcohol resin has a viscosity of from about 2 cps to
about 8 cps; more
generally, the polyvinyl alcohol resin has a viscosity of from about 3 cps to
about 30 cps. From
about 3 cps to about 8 cps is one preferred range as is a viscosity of from
about 3 cps to about 7
cps. Preferably, the polyvinyl alcohol resins are hydrolyzed on a mole percent
basis of from
about 80 to about 99.5 percent; typically, the polyvinyl alcohol resin is
hydrolyzed on a mole
percent basis of from about 85 percent to about 90 percent and has a degree of
polymerization of

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
9
from about 50 to about 2000. Typically, the polyvinyl alcohol resin has a
degree of
polymerization of from about 50 to about 300.
In some preferred embodiments, the optical brightener active ingredient
comprises a
stilbene compound and may be a sulfonated stilbene compound, such as a
tetrasulfonated
stilbene compound or a hexasulfonated stilbene compound. One preferred class
is wherein the
optical brightener active ingredient comprises a stilbene compound of the
formula:
Y
I O wherein X and Y are independently selected from the moieties indicated
below:
Disulfo Tetrasulfo 1 , Tetrasulfo 2 ~ '~ Hexasulfo
~CH2CH~OH
N\CH CH OH ~CH2CH~OH -N CH2CHOH ~CH2CH20H
2 2 -N \ -N
\CH2CH20H CH~~ HOH \CH2CH20H
CH3
H N N N ~ S03Na
-N
Y
S03Na
S03Na NaO3S
In another aspect of the invention there is provided a method of preparing an
optical
brightener/PVOH aqueous concentrate comprising the sequential steps o~
preparing an aqueous
PVOH slurry; adding a dry, particulate optical brightener to the aqueous PVOH
slurry; and

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
cooling the slurry containing PVOH and optical brightener to dissolve the PVOH
resin for at
Ieast 5 minutes at a temperature of above about I60°F.
In yet another aspect of the invention there is provided a method of preparing
an optical
brightener/PVOH aqueous concentrate comprising the sequential steps of:
providing a dry
5 powder optical brightener; providing a dry polyvinyl alcohol resin; dry
blending said polyvinyl
alcohol resin with said optical brightener in an amount of about 1 part of dry
polyvinyl alcohol
resin per 0.05 to 1 part of optical brightener; admixing said dry blend with
water to provide a
nascent aqueous concentrate of polyvinyl alcohol resin and optical brightener;
and cooking the
aqueous concentrate to dissolve the solids at an elevated temperature for a
time sufficient to
10 dissolve substantially all of the polyvinyl alcohol resin and optical
brightenex so as to provide a
cooled brightener/polyvinyl alcohol concentrate including water, polyvinyl
alcohol resin,
optical brightener, and optionally minor amounts of auxiliaries.
Still another feature is a dry, particulate blend of a polyvinyl alcohol resin
and an optical
brightener wherein the polyvinyl alcohol resin is 85-90 mol% hydrolyzed and
has a degree of
polymerization ranging from about 50 to about 600. The polyvinyl alcohol resin
is preferably
85-90 mol% hydrolyzed and has a degree of polymerization ranging from about
185 to about
235. Still more preferably, the polyvinyl alcohol resin is 87-89 mole%
hydrolyzed and has a
viscosity of from about 2 cps to about 8 cps.
A preferred "no cools" process for making a color coat composition includes:
(a)
preparing a pigment dispersion; (b) preparing a dry blend of polyvinyl alcohol
resin and optical
brightener, wherein the polyvinyl alcohol resin is from about 85 mol% to about
90 mol%
hydrolyzed and has a fme particle size, such that at least about 99% of the
particles pass an 80
mesh sieve; (c) adding the dry blend of polyvinyl alcohol resin and optical
brightener to the
pigment dispersion; and (d) applying shear to the pigment dispersion
containing the polyvinyl
alcohol and optical brightener so as to mix the dispersion and dissolve both
the optical
brightener and polyvinyl alcohol resin without external heating.
There is still further provided a method of preparing an optical
brightener/PVOH
aqueous concentrate by way of the sequential steps of: (a) providing an
aqueous brightener
composition including water and optical brightener active ingredient, wherein
the optical
brightener active ingredient is present in the aqueous brightener composition
typically in an
amount of from about 10% to about 25%'; (b) admixing a polyvinyl alcohol resin
with said
aqueous optical brightener composition in an amount of about 1 part of dry
polyvinyl alcohol
resin per 0.25 to 10 wet parts of aqueous brightener composition to provide a
nascent aqueous

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
11
concentrate of polyvinyl alcohol resin and optical brightener; and (c)
coolcing the aqueous
concentrate to dissolve substantially all of the PVOH resin, usually at a
temperature of from
about 175°F to about 210°F generally for a time of from about 10
minutes to about 120 minutes
to provide a coolced brightener/polyvinyl alcohol concentrate consisting
essentially of water,
polyvinyl alcohol resin and optical brightener active ingredient. Typically,
the polyvinyl alcohol
resin is admixed in an amount of about 1 part of dry polyvinyl alcohol resin
per 0.5 to 10 wet
parts of aqueous brightener composition.
The optical brightener active ingredient is usually present in the aqueous
brightener
composition in an amount of from about 12% to about 20% and the optical
brightener/PVOH
aqueous concentrate typically has a solids content of from about 20% to about
75% based on the
water, polyvinyl alcohol and optical brightener active ingredient content of
the concentrate.
More typically, the polyvinyl alcohol is admixed with the aqueous optical
brightener
composition in an amount of from about 15% to about 55% PVOH based on the
combined
weight of the water, the optical brightener active ingredient and polyvinyl
alcohol resin, the
concentrate having a solids content of from about 30 to about 60%. Lilcewise,
the aqueous
concentrate is usually cooked to dissolve the solids at a temperature of from
about 185°F to
about 205°F for a time of from about 20 minutes to about 60 minutes.
Suitable polyvinyl
alcohol resins have viscosities of from about 2 or 3 cps to about 30 or 40
cps; most preferably in
some cases the polyvinyl alcohol resin has a viscosity of from about 2 or 3
cps to about 7 or 8
cps or from about 3 cps to about 4 cps.
The polyvinyl alcohol resin is generally hydrolyzed on a mole percent basis of
from
about 80 to about 99.5 percent; typically, the polyvinyl alcohol resin is
hydrolyzed on a mole
percent basis of from about 85 percent to about 90 percent and has a degree of
polymerization of
from about 50 to about 2000. A degree of polymerization of from about SO to
about 1700 is
more preferred as is a degree of polymerization of from about 50 to about 300.
Most preferably, the polyvinyl alcohol resin is added to the aqueous
brightener
composition in substantially dry form; and sometimes the step of diluting the
aqueous
concentrate is expedient, depending on processing characteristics sought. So
also, the
concentrate can be directly applied to a paper substrate in a size press, if
so desired.
The method may further include the step of adding polyethylene glycol to the
aqueous
concentrate and wherein the polyethylene glycol is added to the aqueous
brightener composition
or to the nascent or cooked aqueous concentrate in a~.i amount of from about
0.5 to about 2 parts
by weight per dry part of polyvinyl alcohol resin.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
12
One preferred method of preparing a color coat composition includes the
sequential steps
of:
(a) providing an aqueous brightener composition consisting essentially of
water and optical
brightener active ingredient, wherein the optical brightener active ingredient
is present in the
aqueous brightener composition in an amount of from about 10 to about 25%;
(b) admixing a polyvinyl alcohol resin with said aqueous optical brightener
composition in
an amount of about 1 part of dry polyvinyl alcohol resin per 0.25 to 10 wet
parts of aqueous
brightener comlposition to provide a nascent aqueous concentrate of polyvinyl
alcohol resin
and optical brightener;
(c) cooking the aqueous concentrate to dissolve the solids at a temperature of
from about
175°F to about 210°F for a time of from about 10 minutes to
about 120 minutes to provide a
cooked brightener/polyvinyl alcohol concentrate consisting essentially of
water, polyvinyl
alcohol resin and optical brightener compounds; and
(d) admixing the cooked concentrate with an aqueous dispersion comprising
color pigment
and a binder resin to produce the color coat composition. Typically, the
polyvinyl alcohol resin
is admixed in an amount of about 1 part of dry polyvinyl alcohol resin per 0.5
to 10 wet parts of
aqueous brightener composition.
The method may further include the step of applying the color coat to paper.
An optical brightener aqueous concentrate consists essentially of water, an
optical
brightener active ingredient and a polyvinyl alcohol resin having a viscosity
of from about 2 cps
to about 4 cps, wherein the aqueous concentrate is from about 20 to about 75%
solids, and the
polyvinyl alcohol resin is hydrolyzed from about 80 to about 90 percent on a
molar basis. The
concentrate optionally includes auxiliaries such as dispersing agents,
protective colloids,
solvents for the colloids, and/or antifreezes, sequestering agents and the
lilce, none of which
change the basic and novel characteristics of the concentrates. When referring
to the optical
brightener/PVOH aqueous concentrate, auxiliaries also include minor amounts of
binder,
plasticizes, filler, water retention aids such as caxboxymethyl cellulose and
so forth. Typically,
the polyvinyl alcohol resin has a viscosity of from 3 cps to 4 cps and the
aqueous concentrate is
from about 25 to about 65 percent solids. The optical brightener concentrate
further comprises
polyethylene glycol in some cases and the optical brightener active ingredient
comprises a
stilbene compound. The stilbene compound may be a sulfonated stilbene compound
as noted
above.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
13
In still yet another aspect of the invention, an optical brightener aqueous
concentrate
consists essentially of water, an optical brightener active ingredient,
polyethylene glycol and a
polyvinyl alcohol resin has a viscosity of from about 2 cps to about 4 cps,
wherein the aqueous
concentrate is from about 20 to about 75% solids, and wherein the polyvinyl
alcohol resin is
hydrolyzed from about 80 to about 90 percent on a molar basis.
As used herein, terminology has its ordinary meaning unless a more specific or
more
general meanng is given below or is clear from the context.
%, percent or per cent means weight percent unless mole percent is specified.
"Cps" means centipoise.
"Minor amount" means less than 50% by weight exclusive of water content.
"PVOH" means polyvinyl alcohol resins which are typically prepared from
polyvinyl
acetate resins by saponification thereof which is well known in the art. PVOH
resins are derived
from homopolymers of vinyl acetate as well as copolymers of vinyl
°acetate with other
ethyleucally unsaturated monomers and may include cationic sites if so
desired. Preferably, the
resins are 95 mole percent or more vinyl acetate derived. Suitable resins,
available from
Celanese, Inc. include:
Table 1: Polyvinyl Alcohol Resins
Grade % Hydrolysis,Viscosity,pH
cpsl
Celvo1125 99.3+ 28-32 5.5-7.5
Celvo1165 99.3+ 62-72 5.5-7.5
Fully Hydrolyzed
Celvo1103 98.0-98.8 3.5-4.5 5.0-7.0
Celvo1305 98.0-98.8 4.5-5.5 5.0-7.0
Celvo1107 98.0-98.8 S.5-6.6 5.0-7.0
Celvo1310 98.0-98.8 9.0-11.0 5.0-7.0
Celvo1325 98.0-98.8 28.0-32.0 5.0-7.0
Celvol 350 I 98.0-98.8I 62-72 I 5.0-7.0

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
14
Table 1: Polyvinxl Alcohol Resins~continued
Hydrolysis,Viscosity,pH
Grade cps
Intermediate
Hydrolyzed
Celvo1418 91.0-93.0 14.5-19.5 4.5-7.0
Celvo1425 95.5-96.5 27-31 4.5-6.5
Partially
Hydrolyzed
Celvo1502 87.0-89.0 3.0-3.7 4.5-6.5
Celvo1203 87.0-89.0 3.5-4.5 4.5-6.5
Celvo1205 87.0-89.0 5.2-6.2 4.5-6.5
Celvo1513 86.0-89.0 13-15 4.5-6.5
Celvo1523 87.0-89.0 23-27 4.0-6.0
Celvol540 87.0-89.0 45-55 ~ 4.0-6.0
14% aqueous solution, 20°C
When the viscosity of a polyvinyl alcohol resin is specified, the viscosity is
the viscosity
of a 4% aqueous (wt/wt) solution of the PVOH, at 20°C.
Suitably, 'CIE L*, a*, b* and brightness values are used to characterize
coated products
prepared with coating formulations of the invention. L*, a*, and b* values may
be suitably
measured using test methods such as TAPPI T 524 om-02, TAPPI T 527 om-02, or
similar
methods. TAPPI T 524 incorporates 45° directional illumination and
perpendicular (0°)
observation geometry. TAPPI T 527 incorporates diffuse illumination and
0° observation
geometry. L* is a measure of lightness increasing from 0 for black to 100 for
perfect white; a*
indicates redness when positive and green when negative; b* indicates
yellowness when positive
and blueness when negative. Note that (GE) brightness is measured in
accordance with TAPPI
T 452 om-02. TAPPI 452 incorporates 45° illumination and 0°
observation geometry. Unless
otherwise indicated, Brightness values are reported with ultra-violet (UV)
radiation. To
calculate Brightness without UV, the UV component is subtracted from the UV
Brightness.
"Slurry" refers to an aqueous composition including undissolved solids.
A "color coat composition" includes aqueous pigment dispersion and optionally
a
synthetic binder resin. Typical binder resins are styrene-butadiene latexes or
polyvinyl acetate
emulsions. Polyvinyl alcohol resins are binder resins, preferably used as a co-
binder.
The aqueous pigment dispersion with wluch the inventive concentrates axe
combined
typically consists of clay or calcium carbonate or mixtures of the two at
solids levels ranging
from about 70 to 76%. In general, at least a portion of the pigment comprises
calciiun carbonate

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
and for the clay portion, any of the clays customarily used for the paper
coating, such as the
hydrous aluminum silicates of the kaolin group clays, hydrated silica clays
and the life can be
used. In addition to the calcium carbonate and clay, there may be added other
paper pigments,
such as, for example titanium dioxide, blanc fixe ("barium sulfate"),
lithopone, zinc sulfide, or
5 other coating pigments, including plastics, for example, polystyrene, in
various ratios, for
example, up to 50 wt.%., preferably up to 35 wt.% based on calcium carbonate
and clay.
Additionally, the composition may also contain other additives, such as zinc
oxide and/or a
small amount of a dispersing or stabilizing agent, such as tetra-sodium
pyrophosphate.
Suitable low molecular weight, partially or mostly hydrolyzed polyvinyl
alcohols for the
10 practice of this invention can be 70-99.5%, preferably 85-90, acid most
preferably 87-89, mole% .
hydrolyzed and have a degree of polymerization (DP) ranging fiom 50-600,
preferably 185 to
255. Another mea~.zs for assessing the DP of the polyvinyl alcohol is its
viscosity as a 4 wt.%
aqueous solution at 20°C. Suitable polyvinyl alcohols have a viscosity
ranging from about 2 to
30 cps, preferably 3=4 cp. Such polyvinyl alcohols can be prepared by
synthesis and
15 saponification techniques well known to those skilled in the art of
manufacturing polyvinyl
alcohol. A preferred polyvinyl alcohol having a viscosity of about 4 cp and an
87-89 mole%
hydrolysis is marketed by Celanese under the trademarlc CELVOL° 203.
Another preferred
polyvinyl alcohol is CELVOL° 502, which has a viscosity of about 3 cp.
The polyvinyl alcohol
is incorporated as a dry powder with the dry OB. The optical brightener active
ingredients are of
the stilbene class noted above and have the general structure of structures A,
B and C. Suitable
stilbenes are disclosed in United States Patent No. 6,620,294 and United
States Patent No.
5,830,241, the disclosures of which are incorporated by reference.
Commercially available
optical brighteners include UVITEX° and TINOPAL° from Ciba
Specialty Chemicals,
BLANKOPHOR° from Bayer and HOSTALUX°, LEUCOPHOR°
from Clariant and
PARAWHITE" from Paramount.
The high solids aqueous pigment dispersion containing the polyvinyl alcohol as
a co-
binder can then be used to prepare paper coating compositions comprising
(parts by wt): 100
parts pigment containing clay and/or calcium carbonate and 0 to 35 parts
secondary pigment;
0.01 to 0.5 parts dispersing or stabilizing agent; 1 to 30 parts polymer
binder emulsion (solids
basis); 0.1 to 10 parts, preferably 0.5 to 2 parts, polyvinyl alcohol co-
binder; 0.1 to 20 parts
other co-binders; 0 to 0.2 parts defoamer, and sufficient water to provide the
desired level of
solids, usually about 45 to 70 wt.%, preferably 60 to 70 wt.% or more for high
solids paper
coating compositions.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
16
The coating compositions produced may be applied to fibrous paper webs using
any of
the conventional coating devices, including trailing blade coaters, air-knife
coaters roll coaters,
and the like.
It is possible to cools the PVOH in the presence of OB as delivered at ~17%
solids
without the addition of water as hereinafter described.
The appearance of the resulting cooked blend, other than viscosity, does not
change.
Because of the viscosity, sometimes dilutions axe desirable. However, at 27%
blends
solids, the papermaker has the benefit of a relatively high solids solution.
For all the formulations discussed below, pigments are primarily calcium
carbonate and
clay, but may include titanium dioxide. There are optionally other ingredients
such as
carboxymethyl cellulose, lubricants, dyes, defoamers, as is well known in the
art. Units are
expressed as dry pts/100 pigment, except for the OB. In terms of raw
materials, pigments are
delivered in dry or in water pre-dispersed form that may range from about 70%
to 76% solids.
Styrene butadiene latexes are delivered at about 50% solids. PVOH may be
delivered in solid
form to be coolced into solution prior to using, or in liquid form at 15% to
30% solids. OBs for
coating are delivered in liquid form at about 17% active ingredient, and are
most preferably of
the tetra or hexa sulfonated variety.
Blends and coatings include 1/1, 2/l, 3.75/1 and 5/1 wet OB (Ciba's
TINOPAL° PT, a
tetrasulfonated form)/dry PVOH (CELVOL~ 203)
Normal operations in paper mills call for PVOH and OBs to be added each as
liquids
into the formulating tank. However, the invention takes advantage of the water
in the OB
through the addition of dry PVOH to 100 pts of OB slurry in a vessel while
stirring sufficiently
to disperse the PVOH particles in a uniform fashion. The contents are then
heated to 185°F to
205°F, depending upon the grade of PVOH used, preferably by steam
heated water bath. The
temperature of the blend is held at temperature for 30 minutes, at which time
the PVOH will be
totally solubilized and the blend may be either cooled or used hot. The solids
levels above axe
considered maximum since no dilutions have taken place.
As shown below, in the various Examples, the method of this invention results
in paper
coating formulations with higher total coating solids than can be achieved by
conventional
methods. Using current methodology, for the ratios of OB/PVOH indicated and
utilizing
standard pigment dispersions of either 70% or 76% solids, the maximum coating
solids that can
be achieved, by adding the OB and PVOH (25% solids) each as liquids, range
from 64.4% to
70.0% and 69.0% to 70.2% (using 30% solids PVOH).

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
17
In contrast, the method of this invention adds dry PVOH to an OB solution.
After the dry
PVOH is added, the formulation is heated for 30 minutes at temperatures
ranging from 185°F to
about 205°F to completely solubilize the PVOH. This solution is then
added to either a 70% or
76% solids pigment dispersion to achieve the final coating solids shown below.
Color coat formulations are sometimes expressed in dry parts and wet parts per
100 parts
dry pigment. A typical or "standard" coating formulation is as follows:
100 parts dry pigment at 70% solids = 142.9 wet parts
14 cliy parts latex at 50% solids = 28 wet parts
0.34 dry parts at 17% Active Ingredient = 2 wet parts
1 dry part PVOH at 25% solids = 4 wet parts
Table 2 below shows solids content for a standard formulation with 2/1 wet
parts/dry
pants OB/PVOH ratio per 100 parts of pigment by way of conventional
formulation techniques.
Table 2: Sample Calculation
Dry PartsIn redient Wet arts
100 Pigment at 70% 142.9
solids
14 Latex at 50% solids28.0
0.34 OB at 17% solids 2.0
1.0 PVOH at 25% solids4
115.34 TOTALS 176.9
Solids Percentage
65.2%
With the invention, carrier water from the PVOH resin composition is
eliminated and the
same "dry" formulation (2/1 wet OB/dry PVOH) has the composition shown in
Table 3, with a
solids advantage of 1.1% overall.
Table 3: Sample Calculation
Dry PartsIn redient Wet arts
100 Pigment at 70% solids142.9
14 Latex at 50% solids 28.0
1.34 OB/PVOH at 44.7% 2.99
solids*
115.34 TOTALS 173.89
Percentage = 66.3%
'The foregoing uses the 44.7% solids solution shown
in Example Series 2 with the 70% pigment dispersion.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
18
Following are numerous additional examples and comparative examples showing
the
solids advantages realized with the invention as opposed to conventional
formulation
techniques. These examples use the standard components specified above,
varying wet OB/dry
PVOH ratios and pigment solids content.
1/1 Wet OB/Dry PVOH
COMPARATIVE EXAMPLE Series A
The color coat is formulated with either 70% or 76% solids pigment dispersions
and 25%
or 30% PVOH solution. Using the standard methodology of mixing liquid OB
(usually 17%
solids) with liquid PVOH, and adding to the pigment dispersion, the solids
that can be achieved
is shown below in Table 4:
Table 4: 1/1 Wet OB/Dry PVOH
CufresZt Methodology
Ingredients Added Separately
Solids
Pigment Coating Solids,
70% 65.5% using 25% solids
PVOH
76% 70.0% usin 25% solids
PVOH
76% 70.2% using 30% solids
PVOH
EXAMPLE Series 1
In contrast to the above, the,invention utilizes a solution prepared by adding
dry PVOH
to a 17% solution of OB to achieve the following concentrations. In this case,
the OB/PVOH
solution is prepared as follows:
83 pts water and 17 pts active ingredient OB + 100 pts dry PVOH. Dry solids =
(100 + 17)/200
= 58.5%; cooled as noted above.
This solution is subsequently added to the pigment dispersion to achieve the
results
shown in Table 5:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
19
Table 5: 1/1 Wet OB/Dry PVOH
Invention
Pre-Blehd
One
Addition
Process
No Dilution
of
Blend
Solids Coating % Solids
Pigment% Solids Advantage
70 66.6 +1.1
76 71.2 +1.2
76 71.2 +1.0
As cm be seen from the above table, there is a distinct solids advantage over
current
practice.
2/1 Wet OB/Dry PVOH
COMPARATIVE EXAMPLE Series B
Following the procedures outlined above, the maximum solids attainable using
conventional
procedures is shown in Table 6:
Table 6: 2/1 Wet OB/Dry PVOH
Current Methodology
Ingredients Added Separately
Solids
Pigment Coating Solids,
70% 65.2% usin 25% solids PVOH
76% 69.6% using 25% solids PVOH
76% 69.9% using 30% solids PVOH
EXAMPLE Series 2
Dry PVOH is mixed with 17% OB according to the following formula:
83 pts water and 17 pts active ingredient OB + 50 pts dry PVOH. Dry solids =
(50 +17)/150 =
44.7%; followed by coolcing.
This is added to the pigment dispersion to achieve the results and solids
'advantage shown in
Table 7:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
Table 7: 2/1 Wet OB/Dry PVOH
Iuvehtiosz
Pre Blend
One Addition
Process
No Dilution
of Blend
Solids Coating % Solids
Pigment % Solids Advantage
70 66.3 +1.1
76 70.9 +1.3
76 70.9 +1.0
3.75 WET OB/DRY PVOH
5 COMPARATIVE EXAMPLE Series C
Following the above, the following maximum solids are achieved:
Table 8 - 3.75/1 Wet OB/Dry PVOH
Curf~etzt Methodology
Ingredients Added Separately
Solids
Pigment Max Coating Solids Possible,
70% 64.7% using 25% solids PVOH
76% 69.1% using 25% solids PVOH
76% 69.4% using 30% solids PVOH
10 EXAMPLE Series 3
PVOH/OB mixture follows the formula below:
83 pts water and 17 pts active ingredient OB + 26.7 pts dry PVOH. Dry solids =
(26.7 +
17)/126.7 = 34.5; followed by cooling. The results are shown in Table 9:
15 Table 9~ 3 75/1 Wet OB/Dry PVOH
Inve~ztio~z
Pre-Blend
One Addition
Process
No Dilution
of Blend
Solids Coating % Solids
Pigment % Solids Advantage
70 65.8 +1.1
76 70.4 +1.3
76 70.4 +1.0

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
21
5/1 WET OBIDRY PVOH
COMPARATIVE EXAMPLE Series D
Similarly, current practice yields the following maximum % solids:
5,, Table 10: 5/1 Wet OB/Dry PVOH
Curreyzt Methodology
Ingredients Added Separately
Solids
Pigment Coating Solids,
70% 64.4% using 25% solids PVOH
76% 68.7% using 24% solids PVOH
76% 69.0% using 30% solids PVOH
EXAMPLE Series 4
The OB/PVOH solution is prepared as follows:
83 pts water and 17 pts active ingredient OB + 20 pts dry PVOH. Dry solids =
(20 + 17)/120 =
30.8%; followed by cooling.
The results are shown in Table 11:
Table 11: 5/1 Wet OB/Dry PVOH
Ifzventioh
Pre-Blend
One Addition
Process
No Dilution
of Blend
Solids Coating % Solids
Pigment % Solids Advantage
70 65.5 +1.1
76 70.0 +1.3
76 70.0 +1.0
The results for the above Examples are summarized in Table 12 below:

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
22
Table 12
CurrentMetlaodologyInvention
Pre
Blehd
Ingredients Added One
Addition
Process
Ratio OB/PVOH Separately No
Dilution
of
Blend
Wet pts/Dry Coating
Pts
per 100 % Solids % CoatingSolids
pts
Pigment PigmentCoating Solids, Solids% SolidsAdvanta
% a
65.5% using 25%
solids
1/1 70% PVOH 58.566.6 +1.1
65.2% using 25%
solids
2/1 PVOH 44.766.3 +1.1
64.7% using 25%
solids
3.75/1 PVOH 34.465.8 +1.1
64.4% using 25%
solids
5/1 PVOH 30.865.5 +1.1
70.0% using 25%
solids
1/1 76% PVOH 58.571.2 +1.2
69.6% using 25%
solids
2/1 PVOH 44.770.9 +1.3
69.1% using 25%
solids
3.75/1 PVOH 34.470.4 +I.3
68.7% using 24%
solids
5/1 PVOH 30.870.0 +1.3
70.2% using 30%
solids
1/1 76% PVOH 58.57I.2 +1.0
69.9% using 30%
solids
2/1 PVOH 44.770.9 +1.0
69.4% using 30%
solids
3.75/I PVOH 34.470.4 +1.0
69.0% using 30%
solids
5/1 PVOH 30.870.0 +1.0
E~~AMPLE Series 5
The above formulations of this invention represent no dilutions in the blend.
Viscosities
at the 3.75/1 ratio were 10,000 cps and at 2/1 greater than 73,000 cps,
because of increasing
solids, Blends at the 5/1 ratio were 4,000 - 5,000 cps initially through 3
days at 30.8% solids.
It is desirable in some cases to achieve a standard target of 27% total solids
by dilution of
the inventive formulations. At this level, the viscosity of all of the PVOH/OB
concentrates
ranged from 2,000 - 4,000 cps and there was still exhibited a solids advantage
over conventional
practice, as shown in Table I3 below.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
23
Table 13
Ratio
OB/PVOH CurrentMetlzodolo ' Invention
Pre B_lend*
Wet pts/DryTngredients Added
Pts Se aratel Coatin % Solids
Per 100 Max Coating Solids Viscosity,
pts
Pi meat Possible, % c s % Solids Advanta
a
65.5% using 2S%
solids
I/1 PVOH 2000-400065.7 +0.2
65.2% using 25%
solids
2/1 PVOH 2000-400065.5 +0.3
64.7% using 2S%
solids
3.75/1 PVOH 2000-400065.3 +0.6
64.4% using 25%
solids
5/1 PVOH 2000-400065.2 +p.8
70.0% using 25%
solids
1/1 PVOH 2000-400070.2 +0.2
69.6% using 25%
solids
2/1 PVOH 2000-400070.0 +0.4
69.1% using 2S%
solids
3.75/1 PVOH 2000-400069.8 +0.7
68.7% using 24%
solids
S/1 PVOH 2000-400069.6 +0.9
70.2% using 30%
solids
111 PVOH 2000-400070.2 0.0
69.9% using 30%
solids
2/1 PVOH 2000-400070.0 +0.1
69.4% using 30%
solids
3.75/1 PVOH 2000-400069.8 +0.4
69.0% using 30%
solids
Sh PVOH 2000-400069.6 +0.6
* All formulations diluted to 27% solids
EXAMPLES 6-10, COMPARATIVE EXAMPLE Series E
These examples show that the novel process of this invention does not impair
the
performance of the optical brightener. The formulation for the paper coatings
was as follows:
7S/2S dry parts CaC03/No. 1 Clay Pigment
14 cliy parts styrene-butadiene latex binder
0.3 dry parts caxboxymethylcellulose water retention aid
x wet parts OB (TINOPAL° PT)
y dry parts PVOH (CELVOL 203 or S02)
Solids ~62%
The formulations were then coated onto paper using a cylindrical coater.
Brightness testing
results appear in Table 14 below.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
24
The control is the basic liquid-liquid addition sequence of PVOH and OB,
whereas
Examples 6-10 are ih-situ pre-cooled PVOH/OB blends as noted above. Example 6
and the
control are both formulated with a 3.75/1 wet OB/dry PVOH. The base paper has
a brightness of
84.3 (standard - no UV). After coating, brightness values of the paper (again -
no LTV) improve
to 85.3 and 85.6. The UV brightness measurements show a very significant
further
improvement to 89.0 and 88.9 - comparable to each other. The a~' value
indicates color shading
to either red or green and these would be considered equal to each other. The
b~= value is
important because it indicates the desirable blue-white with negative values
and undesirable
yellow with positive values. The negative values save desirable and not
significant in their
differences.
Examples 7 and 8 are formulated at 2/1 with OB/dry PVOH and compare the
performance of two PVOH samples with different viscosity values. Both are pre-
coolced with
OB as per the invention. The significance here is that C-502 performs as well
as C-203 and,
since it is lower in viscosity, will allow for higher blend solids from 27% to
30% in the optical
IS brightener concentrate for higher coating color solids benefits.
Following the same procedures, Examples 9 and 10 were formulated at 2/1/I wet
OB/dry
PVOH/polyethylene glycol 400; except that Example 10 had 2 parts less SBR.
Table 14
Bri
fitness
Testin
Invention
27% Solids
Wet Coat Base CoatedCoated UV
.
Forma- OB/dry Wt. Paper Paper Paper Compon
Lbs/ No
lation PVOH 3300ft2UV No With ent a~ b'~
UV UV
Base 84.3
Comp.
Ex. 7.7 85.3 89.0 +3.7 +0.02 -0.37
E1
EX 7 2/I(C-203)7.8 85.4 89.6 +4.2 +0.41 -0.98
2/1 (C-
EX 8 502) 7.4 85.9 89.6 +3.7 +0.37 -1.10
2/1/1
(C-
203)
(PEG
EX 9 400) 7.4 85.7 89.7 +4 +0.50 -1.28
2/1/1
(-2
EX 10
arts
SBR)
7.4
86.2
90
+3.9
+0.48
-1.27
3.75/1
OB
wet
pts/25%
C-203
dry
pts
by
separate
additions

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
EXAMPLES 11 12 and COMPARATIVE EXAMPLES F, G
Following the procedures noted above, color coat compositions were prepared
with
approximately 3/1 and 1/1 wet OB/dry PVOH. The comparative examples had
slightly lower
solids and were prepared in a conventional manner.
In Table 15, 0.51/1 and 0.17/1 refer to the dry ratios of optical brightener
to polyvinyl
alcohol and Comparative Examples F and G use a typical optical brightener such
as TINOPAL~
PT optical brightener with CELVOL° 203 polyvinyl alcohol.
As can be seen from Table 15 below, the inventive concentrates exhibit parity
or better in
the critical optical measurements of UV Brightness, Blue-White "b" value and
CIE Whiteness.
Table 15
0.51!1 a Value~B ValueCIE White UV BrightUV. Comp
Comp. Ex. 0.74 0.3 88.4 89.5 4.3
F
Example 1.09 -0.62 92.9 91.2 5.4
11
0.17/1
Comp. Ex. 0.76 0.43 88.2 89.6 3.6
G
Example 0.72 036 88.6 89.5 3.8
12 ~
Results are also presented graphically in Figures 1-4.
EXAMPLES 13-16
Additional 3/1 and 1/1 wet OB/dry PVOH concentrates were prepared and blended
with
a 75% clay/25% calcium carbonate masterbatch as noted in Tables 16-19 below
Table 16 - Example 13 Formulation
Total Wet
Ingredients Dry Pts Pts
Pigment 100.00 137.36
Latex 14.00 28.00
CMC .030 6.00
3/1 Concentrate0.51/1 5.59

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
26
Table 17 - Example 14 Formulation
Total Wet
Ingredieyts D_ r.~ P_ts
Pigment 100.00 137.36
Latex 14.00 28.00
CMC .030 6.00
1/1 Concentrate0.17/1 4.33
Table 18 - Example 15 Formulation
Total Wet
I~redients Dr~Pts _Pts
Pigment 100.00 137.36
Latex 14.00 28.00
CMC .030 6.00
3/1 Concentrate0.5111 5.59
Table 19 - Example 16 Formulation
?cements Total Wet
Ingredients Dry Pts _Pts
Pigment 100.00 137.36
Latex 14.00 28.00
CMC .03 0 6.00
111 Concentrate0.17/1 4.33
Results of optical testing of the coatings on paper appear in Tables 20 and 21
below.

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
27
Table 20 - Coating Properties
Coat Coat Wt. UV Brightness Avg.
Wt. (1b/3300 BrightnessUV excludedFL
(g) ftz)
Base Paper1.94 33.84 84.00 84.00 0.00
Example 0.51 8.90 89.68 84.86 4.82
13
0.52 9.07 89.60 84.93 4.68
0.58 10.12 90.01 85.24 4.77
Example 0.57 9.94 89.02 85.64 3.38
14
0.59 10.29 88.97 85.59 3.38
0.56 9.77 88.67 85.32 3.35
Example 0.57 9.94 90.19 85.11 5.08
15
0.59 10.29 90.07 85.18 4.89
0.49 8.55 90.12 85.25 4.86
Example 0.49 8.55 88.49 85.26 3.23
16
0.49 8.55 88.13 85.10 3.04
0.52 9.07 88.00 85.16 2.64
Table 21- Coating Properties
L a b CIE White CIE Tint
Example 95.86 0.60 0.45 87.86 -1.38
13
95.86 0.99 0.20 89.02 -1.89
95.93 1.10 0.16 89.35 -2.05
Example 96.04 0.74 0.85 86.49 -1.85
14
95.94 0.75 0.74 86.75 -1.80
95.95 0.62 1.01 85.56 -1.74
Example 95.78 1.19 -0.31 91.15 -1.92
15
95.92 0.95 -0.07 90.39 -1.65
95.95 1.23 0.01 90.03 -2.19
Example 95.95 0.73 0.95 85.81 -1.90
16
96.00 0.49 1.26 84.51 -1.68
95.91 0.43 1.43 83.55 -1.68

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
28
f
EXAMPLES 17, 18, CO1VIPARATIVE EXAMPLES H-M
Following generally the procedures noted above, color coat compositions were
prepared
by substantially conventional techniques (Examples H-M) and by way of adding
dry OB powder
followed by coolcing in-situ in accordance with the invention (Examples 17,
18).
Results appear in Table 22 below as well as Figures 5-8.
Table 22 - Optical Properties
Ratio EX _
3/1 a Value b Value CIE WhiteUV BrightUV Comp
Control H 0.94 0.6 897.4 89.6 4.6
PP/203 1.11 0.19 89.4 90.1 4.5
Dry Add I
PP/203 1.18 0.01 90.1 90 4.8
Water Sln -
J
PP/203 0.61 -0.01 90.3 90 4.7
Coop w/203
Ex 17
In
ControlI~ 0.66 1.12 85.2 88.8 3.3
PP/203 0.86 0.89 86.1 88.9 3.1
Dry Add L
PP/203 0.85 0.89 85.9 88.9 3.2
Water Sin
M
PP/203 0.61 1.08 85.5 88.5 3
Coop w/203
EX. 18
EXAMPLES 19, 20
The following are dry blends and solutions produced in accordance with the
invention.
PVOH/OB Aaueous Concentrate with 3:1 Wet/Dry Ratio
Dry PVOH (10 grams) is added to dry OB (5.1 grams) and the resultant mixture
is dry
blended to produce a uniform mixtuxe of the two ingredients. The dry blend is
then slowly added
to 40 ml of water. The resulting slurry is heated at a temperature of 200-
210°F, with stirring, for
a period of 30 minutes to fully dissolve the dry ingredients. The resulting
solution is cooled to
room temperature to produce a 27.4% solids PVOH/OB concentrate. This example
has an

CA 02547469 2006-05-29
WO 2005/056658 PCT/US2004/040963
29
OB/PVOH ratio equivalent to a solution of 3 wet parts of optical brightener at
17% solids to 1
dry part polyvinyl alcohol resin.
PVOH/OB Aaueous Concentrate With 1:1 Wet/Dry Ratio
Dry PVOH (20 grams) is added to dry OB (3.4 grams) and the resultant mixture
is dry
blended to produce a muform mixture of the two ingredients. The dry blend is
then slowly added
to 50 ml of water. The resulting slurry is heated at a temperature of 200-
210°F, with stirring, for
a period of 30 minutes to fully dissolve the dry ingredients. The resulting
solution is cooled to
room temperature to produce a 31.9% solids PVOH/OB concentrate. This example
has an
OB/PVOH ratio equivalent to a solution of 1 wet part of optical brightener at
17% solids to 1
dry part of polyvinyl alcohol resin.
A dry mixture of PVOH/optical Brightener powder can be added directly to a
pigment
dispersion while preparing a color coat composition if so desired. A preferred
embodiment
utilizes PVOH resin having a particle size of less than about 200 microns,
that is, 99'% by
weight of the resin particles pass through an 80 mesh sieve. This composition
can be readily
dissolved in the coating slurry during mixing with applied shear in the
absence of external
heating.
While the invention has been described in connection with several examples,
modifications to those examples within the spirit and scope of the invention
will be readily
apparent to those of skill in the art. In view of the foregoing discussion,
relevant lcnowledge in
the art and references including co-pending applications discussed above in
connection with the
Baclcground and Detailed Description, the disclosures of which are all
incorporated herein by
reference, further description is deemed unnecessary.

Representative Drawing